WO2013150909A1 - Organic electroluminescent element - Google Patents
Organic electroluminescent elementDownload PDFInfo
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- WO2013150909A1 WO2013150909A1PCT/JP2013/058659JP2013058659WWO2013150909A1WO 2013150909 A1WO2013150909 A1WO 2013150909A1JP 2013058659 WJP2013058659 WJP 2013058659WWO 2013150909 A1WO2013150909 A1WO 2013150909A1
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Definitions
- the present inventionrelates to an organic electroluminescence element.
- ELDelectroluminescence display
- inorganic EL elementsinorganic electroluminescence elements
- organic electroluminescence elementsorganic EL elements
- Inorganic EL elementshave been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements.
- an organic EL devicehas a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode, and injects electrons and holes into the light emitting layer to recombine them, thereby excitons.
- Thisis an element that emits light by utilizing light emission (fluorescence / phosphorescence) when the exciton is deactivated. It can emit light at a voltage of several volts to several tens of volts, and is self-luminous, so it has a wide viewing angle, high visibility, and it is a thin-film, completely solid element that saves space and portability. It is attracting attention from the viewpoint.
- Non-Patent Document 1As the development of organic EL elements for practical use, since Princeton University has reported organic EL elements using phosphorescence emission from excited triplets (see, for example, Non-Patent Document 1), phosphorous at room temperature. Research on materials that exhibit light has become active (see, for example, Non-Patent Document 2 and Patent Document 1). In addition, recently discovered organic EL devices that use phosphorescence can realize a luminous efficiency that is approximately four times that of previous devices that use fluorescence. Research and development of light-emitting element layer configurations and electrodes are performed all over the world. For example, many compounds have been studied for synthesis centering on dopants of heavy metal complexes such as iridium complexes (see, for example, Non-Patent Document 3).
- the dopant concentrationis too high, for example, when a tris body having the same ligand structure is used as the dopant, the dopants are easily stacked and concentration quenching occurs.
- concentration quenchingoccurs as a means for increasing the concentration of the blue dopant, for example, it is conceivable to use a hetero-body having a different ligand instead of a tris-body as a dopant of an iridium complex-based heavy metal complex. As a result, stacking of dopants is suppressed, and even if the concentration of blue dopant is high, concentration quenching does not occur, and the light emission lifetime is not expected to decrease.
- organic EL elementorganic electroluminescent element
- This organic EL elementhas a first dopant having a mixed ligand in the light emitting layer and a second dopant, and mixes two or more types of light emission of the first dopant and light emission of a second dopant different from the first dopant. This improves the color rendering of white.
- the LUMO level of the host compound contained in the light emitting layeris higher than 0.5 eV with respect to the LUMO level of the constituent material of the cathode side adjacent layer of the light emitting layer, Electrons are less likely to be injected into the light emitting layer, resulting in an increase in driving voltage, and the position where recombination of holes and electrons occurs is shifted to the cathode side interface in the light emitting layer, resulting in low luminous efficiency and lifetime performance. Is not enough.
- JP 2007-27679A Japanese Unexamined Patent Publication No. 2011-228569
- a main object of the present inventionis to provide an organic EL element that has no increase in voltage, has high luminous efficiency, and can improve the emission lifetime in a white light emitting organic EL element having at least one light emitting layer. It is to be.
- the inventors of the present inventioninclude a dopant having a specific structure in the light emitting layer, a LUMO (H) level of the host compound of the light emitting layer, and a ligand of the dopant.
- a dopanthaving a specific structure in the light emitting layer
- a LUMO (H) level of the host compound of the light emitting layerand a ligand of the dopant.
- An organic electroluminescence devicehaving at least one light emitting layer,
- the light emitting layercontains a host compound and a dopant represented by the structural formula L 1 L 2 L 3 M (where L 1 to L 3 represent a bidentate ligand and M represents a central metal).
- the LUMO (H) level of the host compound of the light emitting layerthe lowest LUMO (L min ) level among the ligands L 1 to L 3 of the dopant, and the constituent material of the cathode side adjacent layer of the light emitting layer
- an organic electroluminescence devicecharacterized in that the relationship with the LUMO (C) level of the above satisfies the conditional expressions (i) and (ii).
- an organic EL elementthat does not increase in voltage, has high luminous efficiency, and has improved luminous lifetime.
- the present inventorshave found that the host compound and the structural formula L 1 L 2 L 3 M (L 1 to L 3 represent bidentate ligands in the light emitting layer, M represents a central metal.), And at least two arbitrarily selected ligands L 1 to L 3 of the dopant are different, and the LUMO of the host compound of the light emitting layer is different.
- the TT annihilation(triplet-triplet annihilation) is caused by the aggregation of the dopants when the dopant is in a high concentration. It is generally known that Further, in such a system, the dopant is difficult to be uniformly dispersed in the light emitting layer, and the existence distance between the dopants is increased. As a result, when the dopant is responsible for carrier transport, the carrier path is uneven and disturbed, resulting in an increase in voltage. In addition, when the host compound is responsible for carrier transport, the probability of carriers being injected into the dopant is lowered, so the recombination probability is lowered and the light emission efficiency is lowered. Further, the light emission life is reduced accordingly.
- the light emission efficiency and the light emission lifetime of the organic EL elementcan be improved by containing a dopant represented by the general formula (1) described later. That is, at least two arbitrarily selected ligand structures out of the plurality of ligands L 1 , L 2 , and L 3 coordinated to the central metal M are made different between the ligands between the dopants. It was found that the steric hindrance becomes stronger and the interaction between the dopants can be relaxed. Thereby, in the system in which the dopant is dispersed in the host compound in the light emitting layer of the organic EL element, the aggregation state is relaxed by relaxation of the interaction between the dopants. It is considered that the problem that the voltage rise due to the nonuniform and disturbed carrier path can be solved, and further the light emission lifetime can be reduced.
- a dopant represented by the general formula (1) described laterThat is, at least two arbitrarily selected ligand structures out of the plurality of ligands L 1 , L 2 , and L 3 coordinated
- the LUMO levelis designed to have a specific order as described above, electrons are injected from the cathode-side adjacent layer into the host compound, not the dopant, without a barrier load. And, it is predicted that it is transported without load on the host compound occupying most of the light emitting layer. That is, it is considered that the electron transport between the dopant and the dopant is difficult, and when the electron is injected, the hole and the electron are immediately recombined. As a result, it is presumed that the region where holes and electrons recombine is not the vicinity of the interface between adjacent layers, but the central portion of the light emitting layer, and the region becomes wider.
- the dopantsince the band gap of the dopant is narrower than that of the host compound, when the LUMO level is in a specific order, the dopant basically takes charge of transporting holes.
- the holesWhen the dopant is uniformly dispersed in the host compound, the holes are smoothly transported on the dopant, so that the holes are adjacent to the cathode side than the interface on the anode side adjacent layer (for example, hole blocking layer) side. There will be more at the interface on the layer (eg, electron transport layer) side.
- the LUMO levelis in a specific order, electrons are not directly injected into the dopant from the cathode side adjacent layer side interface but are transported on the host compound, so that the recombination region is formed only at the cathode side adjacent layer interface.
- the LUMO level in the present inventionis Gaussian 98 (Gaussian 98, Revision A.11.4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, software for molecular orbital calculation manufactured by Gaussian, USA. 2002.), and by calculating the ionization potential as a value obtained by rounding off the second decimal place of the value (eV unit conversion value) calculated by performing structural optimization using B3LYP / 6-31G * as a keyword can do.
- This calculation valueis effective because the correlation between the calculation value obtained by this method and the experimental value is high.
- the value calculated as the LUMO level of the compound in which the site bonded to the metal is replaced with hydrogenwas used.
- the other light emitting layer adjacent to the light emitting layer containing the dopant represented by the general formula (2) to the general formula (2-2)has a longer wavelength than the above dopant.
- the inclusion of a dopant exhibiting light emissiontransfers energy when the dopant represented by the general formulas (2) to (2-2) returns from the excited state to the ground state to the dopant exhibiting long wavelength light emission. From the ratio, the ratio of the dopant represented by the general formula (2) to the general formula (2-2) is more used as energy for light emission, which is preferable from the viewpoint of efficiently emitting light and improving the lifetime.
- the dopant (heterodopant)is a compound in which light emission from an excited triplet is observed, specifically, a compound that emits phosphorescence at room temperature (25 ° C.), and has a phosphorescence quantum yield of Although defined as a compound of 0.01 or more at 25 ° C., a preferred phosphorescence quantum yield is 0.1 or more.
- the phosphorescent quantum yieldcan be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of the Fourth Edition Experimental Chemistry Course 7.
- the energy transfer typeis to obtain light emission from the phosphorescent dopant, and the other is that the phosphorescent dopant becomes a carrier trap, carrier recombination occurs on the phosphorescent dopant, and light emission from the phosphorescent dopant is obtained.
- the excited state energy of the phosphorescent dopantis required to be lower than the excited state energy of the host compound.
- the phosphorescent dopant of the present inventionhas a phosphorescence lifetime of less than 1.4 ⁇ sec at room temperature (25 ° C.) and a phosphorescence quantum yield of 70% or more when dispersed in the light emitting host compound of the light emitting layer.
- the dopant according to the present inventionis a blue phosphorescent dopant and is represented by the following general formula (1).
- L 1 to L 3represents a bidentate ligand, and at least two arbitrarily selected among “L 1 to L 3 ” are different.
- Mrepresents a central metal.
- Table 1shows the LUMO levels of the above ligands.
- a preferred form of the general formula (1)is represented by the following general formula (2).
- Ring A” and “Ring B”represent a 5- or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic ring.
- Arrepresents an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group.
- R 1 ” and “R 2 ”each independently represent a hydrogen atom or a substituent, and at least one of “R 1 ” and “R 2 ” is an alkyl group or cycloalkyl group having 2 or more carbon atoms. is there.
- Ra”, “Rb” and “Rc”are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group Represents a heteroaryl group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group.
- n a and n cis 1 or 2
- n brepresents an integer of 1-4.
- “L ′”is one or more of monoanionic bidentate ligands coordinated to “M”, and “M” represents a central metal.
- m ′represents an integer of 1 or 2
- n ′represents an integer of 1 or 2
- m ′ + n ′is 3.
- “L ′”is a different ligand.
- R 1 and R 2represent a substituent, it means that they may have a substituent as long as they do not impair the function of the dopant according to the present invention.
- At least one of “R 1 ” and “R 2 ”represents an alkyl group or cycloalkyl group having 2 or more carbon atoms, and the upper limit of the number of carbon atoms is within a range not impairing the function of the dopant according to the present invention. If it is, it will not specifically limit, Preferably it is C10 or less, More preferably, it is 6 or less.
- the groups represented by “Ra”, “Rb” and “Rc”may further have a substituent as long as they do not inhibit the function of the dopant according to the present invention. And the same substituents represented by “Rd ′”, “Rd ′′” and “Rd ′ ′′”.
- a preferred form of the general formula (2)is represented by the following general formula (2-1).
- “Ar”represents an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group.
- “R 1 ” and “R 2 ”each independently represent a hydrogen atom or a substituent, and at least one of “R 1 ” and “R 2 ” is an alkyl group or cycloalkyl group having 2 or more carbon atoms. is there.
- Ra”, “Rb” and “Rc”are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group Represents a heteroaryl group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group.
- n a and n cis 1 or 2
- n brepresents an integer of 1-4.
- “L ′”is one or more of monoanionic bidentate ligands coordinated to “M”, and “M” represents a central metal.
- m ′represents an integer of 1 or 2
- n ′represents an integer of 1 or 2
- m ′ + n ′is 3.
- “L ′”is a different ligand.
- R 1 and R 2represent a substituent, it means that they may have a substituent as long as they do not impair the function of the dopant according to the present invention.
- At least one of “R 1 ” and “R 2 ”represents an alkyl group or cycloalkyl group having 2 or more carbon atoms, and the upper limit of the number of carbon atoms is within a range not impairing the function of the dopant according to the present invention. If it is, it will not specifically limit, Preferably it is C10 or less, More preferably, it is 6 or less.
- the groups represented by “Ra”, “Rb” and “Rc”may further have a substituent as long as they do not inhibit the function of the dopant according to the present invention. And the same substituents represented by “Rd ′”, “Rd ′′” and “Rd ′ ′′”.
- Rd ′”, “Rd ′′” and “Rd ′ ′′”each independently represent a linking site with another group, a hydrogen atom or a substituent, and each “Rd ′”, “Rd” ”And“ Rd ′ ′′ ”may be the same or different, and“ Rd ′ ”,“ Rd ′′ ”, and“ Rd ′ ′′ ”may be bonded to each other to form a ring.
- Rd ′When “Rd ′”, “Rd ′′” and “Rd ′ ′′” represent a substituent, it means that the substituent may be present as long as the function of the dopant according to the present invention is not impaired.
- substituentinclude alkyl groups (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.
- Alkenyl groupseg, vinyl groups, allyl groups, etc.
- alkynyl groupseg, ethynyl groups, propargyl groups, etc.
- non-aromatic hydrocarbon ring groupseg, cycloalkyl groups (eg, cyclopentyl groups, cyclohexyl groups, etc.)
- a cycloalkoxy groupeg, cyclopentyloxy group, cyclohexyloxy group, etc.
- cycloalkyl Thio groupfor example, cyclopentylthio group, cyclohexylthio group, etc.
- tetrahydronaphthalene ring9,10-dihydroanthracene ring, monovalent group derived from biphenylene ring, etc.
- non-aromatic heterocyclic groupfor example, epoxy Ring, aziridine ring, thiirane ring, oxetane ring, a
- aromatic heterocyclic groupfor example, silole ring, furan ring, thiophene ring, oxazole ring, pyrrole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, oxadiazole ring, triazole ring, imidazole Ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzthiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, thienothiophene ring, carbazole ring, azacarbazole ring (carbon atoms constituting carbazole ring) Any one or more of carbon atoms constituting a dibenzosilole ring, dibenzofuran ring, dibenzothiophene ring, benzothi
- Mrepresents a central metal, and examples thereof include Os, Ir, and Pt.
- the compounds represented by the general formulas (2) and (2-1) according to the present inventioncan be synthesized by referring to known methods described in International Publication No. 2006-121811, etc.
- “Ar”represents an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group.
- “R 1 to R 4 ”each independently represents a hydrogen atom or a substituent, and at least one of “R 1 ” and “R 2 ” and at least one of “R 3 ” and “R 4 ” are each carbon.
- Ra”, “Rb”, “Ra ′” and “Rb ′”each independently represent a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, a silyl group, An arylalkyl group, an aryl group, a heteroaryl group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group is represented. n represents an integer of 1 or 2.
- At least one of “R 1 ” and “R 2 ” and at least one of “R 3 ” and “R 4 ”represents an alkyl group or cycloalkyl group having 2 or more carbon atoms, and the upper limit of the number of carbon atoms is The number of carbon atoms is not particularly limited as long as it does not hinder the function of the dopant according to the present invention, and it is preferably 10 or less, more preferably 6 or less.
- the group represented by “Ra”, “Rb”, “Ra ′” and “Rb ′”may further have a substituent as long as the function of the dopant according to the present invention is not impaired.
- substituentsinclude the same substituents represented by the aforementioned “Rd ′”, “Rd ′′” and “Rd ′ ′′”.
- the host compound used in the light emitting layeris a phosphorescent phosphorous compound at a room temperature (25 ° C.) having a mass ratio of 20% or more among the compounds contained in the light emitting layer.
- a photon yieldis defined as a compound of less than 0.1.
- the phosphorescence quantum yieldis preferably less than 0.01.
- a host compound which can be used for this inventionAlthough the compound conventionally used with an organic EL element can be used, The host compound with respect to the blue phosphorescence emission dopant of the light emitting layer of the organic EL element of this invention In particular, those having a structure represented by the following general formula (3) are preferable.
- Xrepresents NR ′, O, S, CR′R ′′ or SiR′R ′′.
- R 1represents a carbazolyl group having a phenyl group or an aromatic heterocyclic group.
- R 2represents a carbazolyl group which may have a substituent.
- R ′ and R ′′each independently represents a hydrogen atom or a substituent.
- R ′ and R ′′represent a substituent, it means that the substituent may have a substituent as long as the function as a host compound according to the present invention is not impaired.
- substituentsinclude alkyl groups (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group).
- cycloalkyl groupeg cyclopentyl group, cyclohexyl group etc.
- alkenyl groupeg vinyl group, allyl group etc.
- alkynyl groupeg ethynyl group, propargyl group etc.
- aromatic hydrocarbon ring groupAlso called aromatic carbocyclic group, aryl group, etc., for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, Ryl group, naphthyl group, anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, biphenylyl group, etc.), aromatic heterocyclic group (for example, pyridyl group, pyrimidinyl group, furyl group, pyrrolyl) Group, imidazolyl group, benzoimid
- examples of the aromatic heterocyclic group contained in “R 1 ”include a pyridyl group, pyrimidinyl group, furyl group, pyrrolyl group, imidazolyl group, benzimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group ( For example, 1,2,4-triazol-1-yl group, 1,2,3-triazol-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group, furazanyl group , Thienyl group, quinolyl group, benzofuryl group, dibenzofuryl group, benzothienyl group, dibenzothienyl group, indolyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (the carbon atom constituting the carboline ring of the carboliny
- the carbazolyl group represented by “R 2 ”may have a substituent represented by R ′ and R ′′ in “X” in General Formula (3). Synonymous with group.
- Xis preferably NR ′ or O
- R ′is an aromatic hydrocarbon group (also referred to as an aromatic carbocyclic group, an aryl group, etc., for example, a phenyl group, a p-chlorophenyl group, Mesityl, tolyl, xylyl, naphthyl, anthryl, azulenyl, acenaphthenyl, fluorenyl, phenanthryl, indenyl, pyrenyl, biphenylyl) or aromatic heterocyclic groups (eg furyl, thienyl) Group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, phthalazinyl group and the like are particularly preferable.
- aromatic hydrocarbon groupalso
- aromatic hydrocarbon group and aromatic heterocyclic groupeach may have a substituent represented by R ′ or R ′′ in “X” of the general formula (3).
- fluorescent dopantsalso referred to as fluorescent compounds
- phosphorescent dopantsalso referred to as phosphorescent emitters, phosphorescent compounds, phosphorescent compounds, etc.
- Fluorescent dopantsinclude coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes, stilbene dyes , Polythiophene dyes, rare earth complex phosphors, and the like, and compounds having a high fluorescence quantum yield, such as laser dyes, are not particularly limited, and are used for the light emitting layer of an organic EL device. It can select suitably from the well-known thing to be used.
- the phosphorescent dopantis preferably a complex compound containing a group 8-10 metal in the periodic table of elements, more preferably an iridium compound, an osmium compound, a platinum compound (platinum complex compound), or a rare earth complex. Among them, the most preferable is an iridium compound.
- the other light emitting layer adjacent to the light emitting layer containing the said blue dopantcontains the green dopant and red dopant which are dopants which show light emission longer wavelength than a blue dopant. It is preferable.
- the light emitting layer according to the present inventionis a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer. If the light emitting material (dopant) contained in the light emitting layer concerning this invention satisfy
- the total thickness of the light emitting layers in the present inventionis preferably in the range of 1 to 100 nm, and more preferably 30 nm or less because a lower driving voltage can be obtained.
- the sum total of the film thickness of the light emitting layer as used in the field of this inventionis a film thickness also including the said intermediate
- the film thickness of each light emitting layeris preferably adjusted in the range of 1 to 50 nm, more preferably in the range of 1 to 20 nm. There is no particular limitation on the relationship between the film thicknesses of the blue, green and red light emitting layers.
- the above-described host compound or light-emitting materialis formed by forming a film by a known thinning method such as a vacuum evaporation method, a spin coating method, a casting method, an LB method, or an inkjet method. it can.
- a plurality of light emitting materialsmay be mixed in each light emitting layer, or a phosphorescent light emitting material and a fluorescent light emitting material may be mixed and used in the same light emitting layer.
- the constitution of the light emitting layerpreferably contains a host compound and a dopant and emits light from the dopant.
- Recombination regionOf the entire region of the light emitting layer, the region contributing to light emission (recombination region) can be calculated from the value of ⁇ PL / ⁇ EL and the width of the region can be estimated from the calculation result.
- ⁇ EL and ⁇ PLrespectively represent the intensity decay rates of electroluminescence (EL) and photoluminescence (PL) before and after driving, and can be represented by the following equations.
- ⁇ EL1 ⁇ [EL (after driving) / EL (before driving)]
- ⁇ PL1 ⁇ [PL (after driving) / PL (before driving)]
- the PL value after the PL drivingis measured in a state after driving the organic EL element until the light emission luminance is about half from the initial luminance ( ⁇ EL is about 0.5).
- ⁇ PLrepresents a recombination region with respect to the entire light emitting layer, it is estimated that the recombination region contributing to light emission is narrow when ⁇ PL / ⁇ EL is small, and light emission occurs when ⁇ PL / ⁇ EL is large. It is presumed that the recombination region contributing is wide.
- 1A to 1Dare schematic views showing respective regions in the layer thickness direction of the light emitting layer 1, and the left-right direction in FIG. 1 corresponds to the layer thickness direction.
- the light emitting layer 1is partitioned into a region contributing to light emission (recombination region 10) and a region 12 not contributing to light emission. Accordingly, the recombination region 10 is a measurement target for “EL before driving”.
- the PL before drivingis the measurement target of the region 20 representing the entire light emitting layer.
- “PL after driving”indicates that the remaining region 22 obtained by subtracting the non-light-emitting region 16 from the region 20 representing the entire light-emitting layer in accordance with the formation of the non-light-emitting region 16 in the recombination region 10 is measured. It becomes.
- An injection layeris a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance.
- Organic EL element and its forefront of industrialization(issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).
- the injection layeris provided as necessary, and may be present between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer as described above.
- hole injection layeranode buffer layer
- hole injection layeranode buffer layer
- copper phthalocyanineis used.
- examples thereofinclude a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.
- cathode buffer layerDetails of the electron injection layer (cathode buffer layer) are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc.
- Metal buffer layertypified by lithium
- alkali metal compound buffer layertypified by lithium fluoride
- alkaline earth metal compound buffer layertypified by magnesium fluoride
- oxide buffer layertypified by aluminum oxide, etc. .
- the injection layeris preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 ⁇ m although it depends on the material.
- ⁇ Blocking layerhole blocking layer, electron blocking layer>
- the blocking layeris provided as necessary in addition to the basic constituent layer of the organic compound thin film as described above. For example, it is described in JP-A Nos. 11-204258 and 11-204359, and “Organic EL elements and the forefront of industrialization (published by NTT Corporation on Nov. 30, 1998)”. There is a hole blocking (hole blocking) layer.
- the hole blocking layerhas a function of an electron transport layer in a broad sense, and is made of a hole blocking material having a function of transporting electrons and a very small ability to transport holes. By blocking the holes, the probability of recombination of electrons and holes can be improved. Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer concerning this invention as needed.
- the hole blocking layer of the organic EL device of the present inventionis preferably provided adjacent to the light emitting layer.
- the hole blocking layerpreferably contains an azacarbazole derivative.
- the light emitting layer having the shortest wavelength of light emissionis preferably closest to the anode among all the light emitting layers.
- 50% by mass or more of the compound contained in the hole blocking layer provided at the positionhas an ionization potential of 0.3 eV or more larger than the host compound of the shortest wave emitting layer.
- the ionization potentialis defined by the energy required to emit electrons at the HOMO (highest occupied molecular orbital) level of the compound to the vacuum level.
- the ionization potentialis obtained by the method shown in (1) and (2) below. Can do.
- Gaussian98(Gaussian98, Revision A.11.4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, 2002.), which is software for molecular orbital calculation manufactured by Gaussian, USA.
- the ionization potentialcan be obtained as a value obtained by rounding off the second decimal place of a value (eV unit converted value) calculated by performing structure optimization using B3LYP / 6-31G * as a keyword. This calculation value is effective because the correlation between the calculation value obtained by this method and the experimental value is high.
- the ionization potentialcan also be obtained by a method of direct measurement by photoelectron spectroscopy.
- a low energy electron spectrometer “Model AC-1” manufactured by Riken Keiki Co., Ltd. or a method known as ultraviolet photoelectron spectroscopycan be suitably used.
- the electron blocking layerhas a function of a hole transport layer in a broad sense, and is made of a material having a function of transporting holes while having a remarkably small ability to transport electrons. The probability of recombination of electrons and holes can be improved by blocking. Moreover, the structure of the positive hole transport layer mentioned later can be used as an electron blocking layer as needed.
- the film thickness of the hole blocking layer and the electron transport layer according to the present inventionis preferably 3 nm to 100 nm, more preferably 5 nm to 30 nm.
- the hole transport layeris made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer.
- the hole transport layercan be provided as a single layer or a plurality of layers.
- the hole transport materialhas any one of hole injection or transport and electron barrier properties, and may be either organic or inorganic.
- triazole derivativesoxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives
- Examples thereofinclude stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.
- the above-mentioned materialscan be used as the hole transport material, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.
- aromatic tertiary amine compounds and styrylamine compoundsinclude N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′— Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminoph
- polymer materials in which these materials are introduced into polymer chains or these materials are used as polymer main chainscan also be used.
- inorganic compoundssuch as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.
- JP-A-11-251067J. Org. Huang et. al.
- a so-called p-type hole transport material described in a book (Applied Physics Letters 80 (2002), p. 139)can also be used.
- these materialsare preferably used because a light-emitting element with higher efficiency can be obtained.
- the hole transport layeris formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Can do.
- the thickness of the hole transport layeris not particularly limited, but is usually about 5 nm to 5 ⁇ m, preferably 5 nm to 200 nm.
- the hole transport layermay have a single layer structure composed of one or more of the above materials.
- a hole transport layer having a high p property doped with impuritiescan be used.
- examples thereofinclude JP-A-4-297076, JP-A-2000-196140, and JP-A-2001-102175. Appl. Phys. 95, 5773 (2004), and the like.
- the electron transport layeris made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer.
- the electron transport layercan be provided as a single layer or a plurality of layers.
- electrons injected from the cathodeare used.
- Any materialcan be used as long as it has a function of transmitting to the light-emitting layer, and any material can be selected from conventionally known compounds. For example, nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrans can be used.
- Dioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives and the likecan be mentioned.
- a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, or a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing groupcan also be used as an electron transport material.
- a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chaincan also be used.
- metal complexes of 8-quinolinol derivativessuch as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), and the like, and the central metals of these metal complexes are In, Mg, Metal complexes replaced with Cu, Ca, Sn, Ga or Pb can also be used as the electron transport material.
- metal-free or metal phthalocyanineor those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material.
- the distyrylpyrazine derivative exemplified as the material for the light emitting layercan also be used as an electron transport material, and an inorganic semiconductor such as n-type-Si, n-type-SiC, etc. as in the case of the hole injection layer and the hole transport layer. Can also be used as an electron transporting material.
- the electron transport layercan be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. .
- the thickness of the electron transport layeris not particularly limited, but is usually about 5 nm to 5 ⁇ m, preferably 5 nm to 200 nm.
- the electron transport layermay have a single layer structure composed of one or more of the above materials.
- an electron transport layer having a high n property doped with impuritiescan also be used.
- examples thereofinclude JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.
- an electrode material made of a metal, an alloy, an electrically conductive compound and a mixture thereof having a high work function (4 eV or more)is preferably used.
- electrode substancesinclude metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO 2 , and ZnO.
- conductive transparent materialssuch as CuI, indium tin oxide (ITO), SnO 2 , and ZnO.
- an amorphous materialsuch as IDIXO (In 2 O 3 —ZnO) capable of forming a transparent conductive film may be used.
- a thin filmmay be formed by depositing these electrode materials by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by photolithography, or when the pattern accuracy is not so high (about 100 ⁇ m or more) ), A pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. Or when using the substance which can be apply
- the transmittanceis greater than 10%, and the sheet resistance as the anode is preferably several hundred ⁇ / ⁇ or less.
- the film thicknessdepends on the material, it is usually selected in the range of 10 nm to 1000 nm, preferably 10 nm to 200 nm.
- cathodea material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used.
- electrode materialsinclude sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al 2 O 3 ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like.
- a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than thisfor example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al 2 O 3 ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred.
- the cathodecan be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering.
- the sheet resistance as a cathodeis preferably several hundred ⁇ / ⁇ or less, and the film thickness is usually selected in the range of 10 nm to 5 ⁇ m, preferably 50 nm to 200 nm.
- the film thicknessis usually selected in the range of 10 nm to 5 ⁇ m, preferably 50 nm to 200 nm.
- a transparent or semi-transparent cathodecan be produced by producing the conductive transparent material mentioned in the description of the anode on the cathode after producing the metal with a film thickness of 1 nm to 20 nm. By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.
- a support substrate(hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention, there is no particular limitation on the type of glass, plastic, etc., and it is transparent. May be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of giving flexibility to the organic EL element.
- polyesterssuch as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfone , Polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylates, cyclone resins such as Arton (trade name, manufactured by JSR) or Appel (trade
- the surface of the resin filmmay be formed with an inorganic film, an organic film, or a hybrid film of both, and the barrier film has a water vapor permeability of 0.01 g / (m 2 ⁇ 24 h ⁇ atm) or less. Further, it is a high barrier film having an oxygen permeability of 1 ⁇ 10 ⁇ 3 ml / (m 2 ⁇ 24 h) or less and a water vapor permeability of 1 ⁇ 10 ⁇ 5 g / (m 2 ⁇ 24 h) or less. preferable.
- any materialmay be used as long as it has a function of suppressing entry of elements that cause deterioration of elements such as moisture and oxygen.
- silicon oxide, silicon dioxide, silicon nitride, or the likecan be used.
- stacking order of an inorganic layer and an organic layerIt is preferable to laminate
- the method for forming the barrier filmis not particularly limited.
- the vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma weight A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, and the likecan be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.
- the opaque support substrateexamples include metal plates such as aluminum and stainless steel, films, opaque resin substrates, ceramic substrates, and the like.
- the external extraction efficiency at room temperature of light emission of the organic EL device of the present inventionis preferably 1% or more, more preferably 5% or more.
- the external extraction quantum efficiency (%)the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element ⁇ 100.
- a hue improving filtersuch as a color filter may be used in combination, or a color conversion filter for converting the emission color from the organic EL element into multiple colors using a phosphor may be used in combination.
- the ⁇ max of light emission of the organic EL elementis preferably 480 nm or less.
- the sealing membermay be disposed so as to cover the display area of the organic EL element, and may be a concave plate shape or a flat plate shape. Further, transparency and electrical insulation are not particularly limited. Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz.
- polymer plateexamples include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone.
- metal plateexamples include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.
- a polymer film and a metal filmcan be preferably used because the element can be thinned.
- the polymer filmhas an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 ⁇ 10 ⁇ 3 ml / (m 2 ⁇ 24 h) or less, and measured by a method according to JIS K 7129-1992.
- the water vapor permeability (25 ⁇ 0.5 ° C., relative humidity (90 ⁇ 2)% RHis preferably 1 ⁇ 10 ⁇ 3 g / (m 2 ⁇ 24 h) or less.
- adhesivesinclude photo-curing and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. Can be mentioned. Moreover, heat
- coating of the adhesive agent to a sealing partmay use commercially available dispenser, and may print like screen printing.
- the electrode and the organic layerare coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film.
- the material for forming the filmmay be any material that has a function of suppressing infiltration of elements that cause deterioration of elements such as moisture and oxygen.
- silicon oxide, silicon dioxide, silicon nitride, or the likemay be used. it can.
- vacuum deposition methodsputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma
- a polymerization methoda plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.
- an inert gassuch as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase.
- a vacuumcan also be used.
- a hygroscopic compoundcan also be enclosed inside. Examples of the hygroscopic compound include metal oxides (eg, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide), sulfates (eg, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate).
- metal halidesfor example, calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide, etc.
- perchloric acidsfor example, perchloric acid
- anhydrous saltsare preferably used in sulfates, metal halides and perchloric acids.
- a protective film or a protective platemay be provided on the outer side of the sealing film or the sealing film on the side facing the support substrate with the organic layer interposed therebetween.
- the mechanical strengthis not necessarily high. Therefore, it is preferable to provide such a protective film and a protective plate.
- the same glass plate, polymer plate / film, metal plate / film, etc. used for sealingcan be used. It is preferable to use it.
- the organic EL elementemits light inside a layer having a refractive index higher than that of air (refractive index is about 1.7 to 2.1), and can extract only about 15% to 20% of the light generated in the light emitting layer. It is generally said that there is no. This is because light incident on the interface (interface between the transparent substrate and air) at an angle ⁇ greater than the critical angle causes total reflection and cannot be taken out of the device, or between the transparent electrode or light emitting layer and the transparent substrate. This is because the light undergoes total reflection between the light and the light, and the light is guided through the transparent electrode or the light emitting layer.
- a method for improving the light extraction efficiencyfor example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the interface between the transparent substrate and the air (US Pat. No. 4,774,435), A method for improving efficiency by giving light condensing property to a substrate (Japanese Patent Laid-Open No. 63-314795), a method of forming a reflective surface on the side surface of an element (Japanese Patent Laid-Open No. 1-220394), and light emission from the substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the bodies (Japanese Patent Laid-Open No.
- a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, transparentA method of forming a diffraction grating between any layers of the electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used. In the present invention, by combining these means, it is possible to obtain an element having higher luminance or durability.
- the low refractive index layerinclude aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Furthermore, it is more preferable that it is 1.35 or less.
- the thickness of the low refractive index mediumis preferably at least twice the wavelength in the medium. This is because the effect of the low refractive index layer is diminished when the thickness of the low refractive index medium is about the wavelength of light and the electromagnetic wave that has exuded by evanescent enters the substrate.
- the method of introducing a diffraction grating into an interface or any medium that causes total reflectionis characterized by a high effect of improving light extraction efficiency.
- This methoduses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction such as first-order diffraction and second-order diffraction.
- the light that cannot be emitted due to total reflection between layers, etc.is diffracted by introducing a diffraction grating into any layer or medium (in the transparent substrate or transparent electrode), and the light is I want to take it out.
- the introduced diffraction gratingdesirably has a two-dimensional periodic refractive index.
- the position where the diffraction grating is introducedmay be in any of the layers or in the medium (in the transparent substrate or in the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated.
- the period of the diffraction gratingis preferably about 1/2 to 3 times the wavelength of light in the medium.
- the arrangement of the diffraction gratingis preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.
- the organic EL device of the present inventioncan be processed on the light extraction side of the substrate, for example, by providing a microlens array-like structure, or combined with a so-called condensing sheet, for example, in a specific direction, for example, the device light emitting surface
- luminance in a specific directioncan be raised by condensing in a front direction.
- quadrangular pyramidshaving a side of 30 ⁇ m and an apex angle of 90 degrees are two-dimensionally arranged on the light extraction side of the substrate. One side is preferably 10 ⁇ m to 100 ⁇ m.
- the condensing sheetfor example, a sheet that is put into practical use in an LED backlight of a liquid crystal display device can be used.
- a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limitedcan be used.
- the shape of the prism sheetfor example, the base material may be formed with a ⁇ -shaped stripe having a vertex angle of 90 degrees and a pitch of 50 ⁇ m, or the vertex angle is rounded and the pitch is changed randomly. Other shapes may be used.
- a light diffusing plateand a film with a condensing sheet.
- a diffusion film (light-up) manufactured by Kimoto Co., Ltd.can be used.
- Organic compound thin filmscan be made by vapor deposition or wet processes (spin coating, casting, ink jet, spray coating, blade coating, air knife coating, wire bar coating, gravure coating, flexographic coating, etc. Coating method, reverse coating method, reverse roll coating method, extrusion coating method, etc.). Different film forming methods may be applied for each layer.
- the vapor deposition conditionsvary depending on the type of compound used, but generally a boat heating temperature of 50 to 450 ° C., a degree of vacuum of 10 ⁇ 6 to 10 ⁇ 2 Pa, and a vapor deposition rate of 0.01 to It is desirable to select appropriately within a range of 50 nm / second, a substrate temperature of ⁇ 50 to 300 ° C., and a film thickness of 0.1 nm to 5 ⁇ m, preferably 5 to 200 nm. In the case of the vapor deposition method, it is preferable to consistently produce from the hole injection layer to the cathode by one evacuation, but it may be taken out halfway and subjected to different film forming methods.
- a thin film made of a cathode materialis formed thereon by a method such as vapor deposition or sputtering so as to have a film thickness of 1 ⁇ m or less, preferably in the range of 50 to 200 nm.
- a metal, an alloy, an electrically conductive compound and a mixture thereof having a low melting pointmay be melted and applied, or a metal dispersion or the like may be applied.
- the organic EL element of the present inventioncan be used as a display device, a display, and various light emission sources.
- lighting deviceshome lighting, interior lighting
- clock and liquid crystal backlightsbillboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light Examples include, but are not limited to, a light source of a sensor.
- the light sourcecan be effectively used for a backlight of a liquid crystal display device and a light source for illumination.
- patterningmay be performed by a metal mask, an ink jet printing method, or the like as needed during film formation. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned. In the fabrication of the element, a conventionally known method is used. Can do.
- organic EL elementAs an anode, a substrate (NA Technoglass NA45) formed by depositing ITO (indium tin oxide) with a thickness of 100 nm on a 100 mm ⁇ 100 mm ⁇ 1.1 mm glass substrate After patterning, the transparent support substrate provided with the ITO transparent electrode was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.
- ITOindium tin oxide
- This transparent support substrateis fixed to a substrate holder of a commercially available vacuum deposition apparatus, while 200 mg of HT-30 having the following structure is placed in a molybdenum resistance heating boat, and HT- 200 mg of a-1 is put in another molybdenum resistance heating boat, 200 mg of a comparative compound having the structure shown below is put in another resistance heating boat made of molybdenum, and Ir- 200 mg of ET-7 having the structure shown below was put in another resistance heating boat made of molybdenum and attached to a vacuum deposition apparatus.
- the pressure in the vacuum chamberwas reduced to 4 ⁇ 10 ⁇ 4 Pa and then heated by energizing a heating boat containing HT-30, and deposited on the transparent support substrate at a deposition rate of 0.1 nm / second.
- a hole injection layerwas provided.
- the heating boat containing HT-2was energized and heated, and deposited on the hole injection layer at a deposition rate of 0.1 nm / second to provide a hole transport layer having a thickness of 30 nm.
- the heating boat containing a-1, comparative compound, Ir-1, and Ir-6was energized and heated, and the deposition rates were 0.1 nm / second, 0.02 nm / second, 0.0001 nm / second, 0, respectively. Co-deposited on the hole transport layer at a rate of .0002 nm / second to provide a 40 nm thick light emitting layer. Further, an electron transport layer (ETL) which is heated by energizing a heating boat containing ET-7, deposited on the light emitting layer at a deposition rate of 0.1 nm / second, and serving as a cathode side adjacent layer of the light emitting layer having a thickness of 30 nm. ).
- ETTLelectron transport layer
- lithium fluoridewas vapor-deposited with a film thickness of 0.5 nm, and aluminum was vapor-deposited with a film thickness of 110 nm to form a cathode, whereby the organic EL element 1 was produced.
- a glass coveris prepared, and an epoxy-based photocurable adhesive (Luxtrac LC0629B manufactured by Toagosei Co., Ltd.) is applied as a sealant to the side edge of the glass cover.
- the surface (cathode side)was adhered to the glass substrate of the organic EL element 1 so as to be covered with a glass cover.
- UV lightwas irradiated from the glass substrate side of the organic EL element 1 to cure the adhesive, and the organic EL element 1 was sealed with a glass cover.
- the organic EL element 1 after the sealingwas designated as “Sample 1”.
- Organic EL elements 2 to 4were prepared in the same manner except that the host compound was changed to the compounds shown in Table 2 in preparation of the organic EL element 1. Samples 2 to 4 were used.
- Organic EL element 5was prepared in the same manner as Sample 5 except that the structure of the light-emitting layer was changed as described below.
- a heating boat containing a-11, Ir-1, and Ir-6was energized and heated, and the deposition rates were 0.1 nm / second, 0.0001 nm / second, and 0.0002 nm / second, respectively. And co-evaporated on the hole transport layer to provide a first light-emitting layer having a thickness of 20 nm.
- a heating boat containing a-9 and DP-1is energized and heated on the first light emitting layer, and the first light emitting layer is coated on the first light emitting layer at a deposition rate of 0.1 nm / second and 0.02 nm / second, respectively.
- the second light emitting layer having a thickness of 20 nmwas provided by vapor deposition.
- each film thickness of the said 1st light emitting layer and the 2nd light emitting layerwas vapor-deposited so that the total film thickness as the whole light emitting layer might be 40 nm.
- Organic EL element 6was prepared in the same manner as Sample 6 except that the structure of the light emitting layer was changed as follows in the preparation of organic EL element 1.
- a heating boat containing a-9 and DP-1is energized and heated, and co-deposited on the hole transport layer at a deposition rate of 0.1 nm / second and 0.02 nm / second, respectively.
- a first light emitting layer having a thickness of 20 nmwas provided.
- the first light emitting layerwas heated by energizing a heating boat containing a-11, Ir-1, and Ir-6, and the deposition rates were 0.1 nm / second, 0.0001 nm / second, and 0.0002 nm, respectively.
- / Secondwas co-evaporated on the first light emitting layer, and a second light emitting layer having a thickness of 20 nm was provided.
- each film thickness of the said 1st light emitting layer and the 2nd light emitting layerwas vapor-deposited so that the total film thickness as the whole light emitting layer might be 40 nm.
- a heating boat containing a-11, Ir-1, and Ir-6was energized and heated, and the deposition rates were 0.1 nm / second, 0.0001 nm / second, and 0.0002 nm / second, respectively. And co-evaporated on the hole transport layer to provide a first light emitting layer having a thickness of 13.3 nm.
- a heating boat containing a-9 and DP-1is energized and heated on the first light emitting layer, and the first light emitting layer is coated on the first light emitting layer at a deposition rate of 0.1 nm / second and 0.02 nm / second, respectively.
- the 2nd light emitting layerIt vapor-deposited and provided the 2nd light emitting layer with a film thickness of 13.4 nm. Further, the second light emitting layer was heated by energizing a heating boat containing a-9, DP-1, and Ir-6, and the deposition rates were 0.1 nm / second, 0.02 nm / second, and 0.0002 nm, respectively. / Second was co-evaporated on the second light emitting layer, and a third light emitting layer having a thickness of 13.3 nm was provided. In addition, each film thickness of the said 1st light emitting layer, the 2nd light emitting layer, and the 3rd light emitting layer was vapor-deposited so that the total film thickness as a whole light emitting layer might be 40 nm.
- Organic EL elements 8 to 10In the preparation of organic EL element 5, the compounds shown in Table 2 are used as constituent materials for the host compound, the blue dopant, and the electron transport layer adjacent to the cathode side of the light emitting layer. Organic EL elements 8 to 10 were produced in the same manner except that the samples were changed to Samples 8 to 10.
- ⁇ EL1 ⁇ [EL (after driving) / EL (before driving)]
- ⁇ PL1 ⁇ [PL (after driving) / PL (before driving)]
- USB spectrummanufactured by Ocean Optics
- PL spectrum measurementwas used for PL spectrum measurement, and the spectrum measurement was performed under conditions of room temperature (23 ° C.) and excitation wavelength of 365 nm.
- the spectrum measurement after the drivewas performed within 2 hours from that time after the EL was driven until the initial luminance became about half. Thereafter, the ratio of each value between ⁇ PL and ⁇ EL ( ⁇ PL / ⁇ EL) was calculated. Table 2 shows the calculation results.
- regionwas represented by the relative value which sets the light emission area of the sample 1 to 100.
- the organic EL elements 3 to 10 of the present inventionare not compared with the organic EL elements 1 and 2 of the comparative example in terms of driving voltage, light emitting region, light emission efficiency, and light emission lifetime.
- the light emitting layercontains a host compound and a heterodopant, and the relationship between the LUMO (H) level of the host compound of the light emitting layer and the lowest LUMO (L min ) level among the ligands of the dopant, the coordination It is possible to define the relationship between the LUMO (L min ) level of the child, the LUMO (C) level of the constituent material of the cathode side adjacent layer of the light emitting layer, and the LUMO (H) level of the host compound of the light emitting layer. It turns out that it is useful for providing the organic EL element which does not raise
- the present inventioncan be particularly suitably used for providing an organic EL device that does not increase in voltage and has excellent luminous efficiency and luminous lifetime.
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Abstract
Description
本発明は、有機エレクトロルミネッセンス素子に関する。The present invention relates to an organic electroluminescence element.
従来、発光型の電子ディスプレイデバイスとして、エレクトロルミネッセンスディスプレイ（ＥＬＤ）がある。ＥＬＤの構成要素としては、無機エレクトロルミネッセンス素子（無機ＥＬ素子）や有機エレクトロルミネッセンス素子（有機ＥＬ素子）が挙げられる。
無機ＥＬ素子は、平面型光源として使用されてきたが、発光素子を駆動させるためには交流の高電圧が必要である。Conventionally, there is an electroluminescence display (ELD) as a light-emitting electronic display device. Examples of the constituent elements of ELD include inorganic electroluminescence elements (inorganic EL elements) and organic electroluminescence elements (organic EL elements).
Inorganic EL elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements.
無機ＥＬ素子は、平面型光源として使用されてきたが、発光素子を駆動させるためには交流の高電圧が必要である。Conventionally, there is an electroluminescence display (ELD) as a light-emitting electronic display device. Examples of the constituent elements of ELD include inorganic electroluminescence elements (inorganic EL elements) and organic electroluminescence elements (organic EL elements).
Inorganic EL elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements.
一方、有機ＥＬ素子は、発光する化合物を含有する発光層を陰極と陽極とで挟んだ構成を有し、発光層に電子および正孔を注入して、再結合させることにより励起子（エキシトン）を生成させ、このエキシトンが失活する際の光の放出（蛍光・リン光）を利用して発光する素子である。数Ｖ～数十Ｖ程度の電圧で発光が可能であり、さらに自己発光型であるために視野角に富み、視認性が高く、薄膜型の完全固体素子であるために省スペース、携帯性等の観点から注目されている。On the other hand, an organic EL device has a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode, and injects electrons and holes into the light emitting layer to recombine them, thereby excitons. This is an element that emits light by utilizing light emission (fluorescence / phosphorescence) when the exciton is deactivated. It can emit light at a voltage of several volts to several tens of volts, and is self-luminous, so it has a wide viewing angle, high visibility, and it is a thin-film, completely solid element that saves space and portability. It is attracting attention from the viewpoint.
実用化に向けた有機ＥＬ素子の開発としては、プリンストン大より、励起三重項からのリン光発光を用いる有機ＥＬ素子の報告がされて以来（たとえば、非特許文献１参照。）、室温でリン光を示す材料の研究が活発になってきている（たとえば、非特許文献２、特許文献１参照。）。
さらに、最近発見されたリン光発光を利用する有機ＥＬ素子では、以前の蛍光発光を利用する素子に比べ原理的に約４倍の発光効率が実現可能であることから、その材料開発を初めとし、発光素子の層構成や電極の研究開発が世界中で行われている。たとえば、多くの化合物がイリジウム錯体系等重金属錯体のドーパントを中心に合成検討がなされている（たとえば、非特許文献３参照。）。As the development of organic EL elements for practical use, since Princeton University has reported organic EL elements using phosphorescence emission from excited triplets (see, for example, Non-Patent Document 1), phosphorous at room temperature. Research on materials that exhibit light has become active (see, for example, Non-Patent Document 2 and Patent Document 1).
In addition, recently discovered organic EL devices that use phosphorescence can realize a luminous efficiency that is approximately four times that of previous devices that use fluorescence. Research and development of light-emitting element layer configurations and electrodes are performed all over the world. For example, many compounds have been studied for synthesis centering on dopants of heavy metal complexes such as iridium complexes (see, for example, Non-Patent Document 3).
さらに、最近発見されたリン光発光を利用する有機ＥＬ素子では、以前の蛍光発光を利用する素子に比べ原理的に約４倍の発光効率が実現可能であることから、その材料開発を初めとし、発光素子の層構成や電極の研究開発が世界中で行われている。たとえば、多くの化合物がイリジウム錯体系等重金属錯体のドーパントを中心に合成検討がなされている（たとえば、非特許文献３参照。）。As the development of organic EL elements for practical use, since Princeton University has reported organic EL elements using phosphorescence emission from excited triplets (see, for example, Non-Patent Document 1), phosphorous at room temperature. Research on materials that exhibit light has become active (see, for example, Non-Patent Document 2 and Patent Document 1).
In addition, recently discovered organic EL devices that use phosphorescence can realize a luminous efficiency that is approximately four times that of previous devices that use fluorescence. Research and development of light-emitting element layer configurations and electrodes are performed all over the world. For example, many compounds have been studied for synthesis centering on dopants of heavy metal complexes such as iridium complexes (see, for example, Non-Patent Document 3).
このような有機ＥＬ素子において、発光層単層で、１つの発光材料で白色を実現する方法として、たとえば、異なる色を発するドーパントを２種以上含むことが報告されている（たとえば、特許文献１参照。）。異なる色を発するドーパントとして、たとえば、青色を発するドーパントと赤色を発するドーパントとを含む場合、ドーパントの量は赤色ドーパント／青色ドーパントの質量比率として１％程度以下で、かつ、このときの青色ドーパントの濃度が１０％未満で調整されていることが多い。
しかし、ドーパントの濃度が低いと発光寿命が低下する原因となる。反対に、ドーパントの濃度を高くしすぎると、たとえば、ドーパントとして配位子の構造がすべて同一であるトリス体を用いた場合には、ドーパント同士がスタックしやすく、濃度消光が起こってしまう。
この青色ドーパントの濃度を高くする手段として、たとえば、イリジウム錯体系等重金属錯体のドーパントにトリス体ではなく、異なる配位子を持つヘテロ体を用いることが考えられる。これにより、ドーパント同士のスタックが抑制され、青色ドーパントを高濃度にしても濃度消光が起こらず、発光寿命が低下しないと予測される。In such an organic EL device, as a method for realizing white color with a single light emitting material with a single light emitting layer, for example, it has been reported that two or more kinds of dopants emitting different colors are included (for example, Patent Document 1). reference.). For example, when a dopant emitting a different color includes a dopant emitting a blue color and a dopant emitting a red color, the amount of the dopant is about 1% or less as a mass ratio of the red dopant / blue dopant, and the blue dopant at this time The concentration is often adjusted to less than 10%.
However, when the dopant concentration is low, the emission lifetime is reduced. On the other hand, if the dopant concentration is too high, for example, when a tris body having the same ligand structure is used as the dopant, the dopants are easily stacked and concentration quenching occurs.
As a means for increasing the concentration of the blue dopant, for example, it is conceivable to use a hetero-body having a different ligand instead of a tris-body as a dopant of an iridium complex-based heavy metal complex. As a result, stacking of dopants is suppressed, and even if the concentration of blue dopant is high, concentration quenching does not occur, and the light emission lifetime is not expected to decrease.
しかし、ドーパントの濃度が低いと発光寿命が低下する原因となる。反対に、ドーパントの濃度を高くしすぎると、たとえば、ドーパントとして配位子の構造がすべて同一であるトリス体を用いた場合には、ドーパント同士がスタックしやすく、濃度消光が起こってしまう。
この青色ドーパントの濃度を高くする手段として、たとえば、イリジウム錯体系等重金属錯体のドーパントにトリス体ではなく、異なる配位子を持つヘテロ体を用いることが考えられる。これにより、ドーパント同士のスタックが抑制され、青色ドーパントを高濃度にしても濃度消光が起こらず、発光寿命が低下しないと予測される。In such an organic EL device, as a method for realizing white color with a single light emitting material with a single light emitting layer, for example, it has been reported that two or more kinds of dopants emitting different colors are included (for example, Patent Document 1). reference.). For example, when a dopant emitting a different color includes a dopant emitting a blue color and a dopant emitting a red color, the amount of the dopant is about 1% or less as a mass ratio of the red dopant / blue dopant, and the blue dopant at this time The concentration is often adjusted to less than 10%.
However, when the dopant concentration is low, the emission lifetime is reduced. On the other hand, if the dopant concentration is too high, for example, when a tris body having the same ligand structure is used as the dopant, the dopants are easily stacked and concentration quenching occurs.
As a means for increasing the concentration of the blue dopant, for example, it is conceivable to use a hetero-body having a different ligand instead of a tris-body as a dopant of an iridium complex-based heavy metal complex. As a result, stacking of dopants is suppressed, and even if the concentration of blue dopant is high, concentration quenching does not occur, and the light emission lifetime is not expected to decrease.
ところで、ドーパントとしてヘテロ体を用いた白色発光の有機ＥＬ素子（有機電界発光素子）に関する技術が開示されている（たとえば、特許文献２参照。）。この有機ＥＬ素子は、発光層に混合配位子を有する第一ドーパントと第二ドーパントとを有し、第一ドーパントの２種以上の発光と、それとは異なる第二ドーパントの発光とを混色することで、白色の演色性を改善している。
しかし、特許文献２の素子構成では、発光層に含まれるホスト化合物のＬＵＭＯ準位が発光層の陰極側隣接層の構成材料のＬＵＭＯ準位に対して０．５ｅＶを超えて高くなっており、電子が発光層へ注入されにくく、結果として、駆動電圧が上昇し、さらには正孔と電子との再結合が起こる位置が発光層中の陰極側界面にずれるため、発光効率が低く、寿命性能が十分ではない。By the way, the technique regarding the organic EL element (organic electroluminescent element) of the white light emission which used the hetero body as a dopant is disclosed (for example, refer patent document 2). This organic EL element has a first dopant having a mixed ligand in the light emitting layer and a second dopant, and mixes two or more types of light emission of the first dopant and light emission of a second dopant different from the first dopant. This improves the color rendering of white.
However, in the element configuration of Patent Document 2, the LUMO level of the host compound contained in the light emitting layer is higher than 0.5 eV with respect to the LUMO level of the constituent material of the cathode side adjacent layer of the light emitting layer, Electrons are less likely to be injected into the light emitting layer, resulting in an increase in driving voltage, and the position where recombination of holes and electrons occurs is shifted to the cathode side interface in the light emitting layer, resulting in low luminous efficiency and lifetime performance. Is not enough.
しかし、特許文献２の素子構成では、発光層に含まれるホスト化合物のＬＵＭＯ準位が発光層の陰極側隣接層の構成材料のＬＵＭＯ準位に対して０．５ｅＶを超えて高くなっており、電子が発光層へ注入されにくく、結果として、駆動電圧が上昇し、さらには正孔と電子との再結合が起こる位置が発光層中の陰極側界面にずれるため、発光効率が低く、寿命性能が十分ではない。By the way, the technique regarding the organic EL element (organic electroluminescent element) of the white light emission which used the hetero body as a dopant is disclosed (for example, refer patent document 2). This organic EL element has a first dopant having a mixed ligand in the light emitting layer and a second dopant, and mixes two or more types of light emission of the first dopant and light emission of a second dopant different from the first dopant. This improves the color rendering of white.
However, in the element configuration of Patent Document 2, the LUMO level of the host compound contained in the light emitting layer is higher than 0.5 eV with respect to the LUMO level of the constituent material of the cathode side adjacent layer of the light emitting layer, Electrons are less likely to be injected into the light emitting layer, resulting in an increase in driving voltage, and the position where recombination of holes and electrons occurs is shifted to the cathode side interface in the light emitting layer, resulting in low luminous efficiency and lifetime performance. Is not enough.
したがって、本発明の主な目的は、少なくとも１層の発光層を有する白色発光型の有機ＥＬ素子において、電圧上昇がなく、発光効率が高く、発光寿命の向上を実現し得る有機ＥＬ素子を提供することである。Accordingly, a main object of the present invention is to provide an organic EL element that has no increase in voltage, has high luminous efficiency, and can improve the emission lifetime in a white light emitting organic EL element having at least one light emitting layer. It is to be.
本発明者らは、上記目的を達成するために鋭意研究を重ねた結果、発光層に特定構造を有するドーパントを含み、発光層のホスト化合物のＬＵＭＯ（Ｈ）準位と、ドーパントの配位子のうち最も低いＬＵＭＯ（Ｌｍｉｎ）準位と、発光層の陰極側隣接層の構成材料のＬＵＭＯ（Ｃ）準位との関係を特定の序列となるように設計することにより、電圧上昇がなく、発光効率が高く、発光寿命を向上できることを見出し、本発明に至ったものである。As a result of intensive studies to achieve the above object, the inventors of the present invention include a dopant having a specific structure in the light emitting layer, a LUMO (H) level of the host compound of the light emitting layer, and a ligand of the dopant. By designing the relationship between the lowest LUMO (Lmin ) level and the LUMO (C) level of the constituent material of the cathode side adjacent layer of the light emitting layer to be in a specific order, there is no increase in voltage The present inventors have found that the light emission efficiency is high and the light emission life can be improved.
そこで、本発明によれば、
少なくとも１層の発光層を有する有機エレクトロルミネッセンス素子であって、
前記発光層には、ホスト化合物と構造式Ｌ１Ｌ２Ｌ３Ｍ（Ｌ１～Ｌ３は二座配位子を表し、Ｍは中心金属を表す。）で表されるドーパントとが含有され、
前記ドーパントの配位子Ｌ１～Ｌ３のうち、少なくとも任意に選択した２つは異なっており、
前記発光層のホスト化合物のＬＵＭＯ（Ｈ）準位と、前記ドーパントの配位子Ｌ１～Ｌ３のうち最も低いＬＵＭＯ（Ｌｍｉｎ）準位と、前記発光層の陰極側隣接層の構成材料のＬＵＭＯ（Ｃ）準位との関係が、条件式（ｉ）および（ii）を満たすことを特徴とする有機エレクトロルミネッセンス素子が提供される。So, according to the present invention,
An organic electroluminescence device having at least one light emitting layer,
The light emitting layer contains a host compound and a dopant represented by the structural formula L1 L2 L3 M (where L1 to L3 represent a bidentate ligand and M represents a central metal). ,
Of the ligands L1 to L3 of the dopant, at least two arbitrarily selected are different,
The LUMO (H) level of the host compound of the light emitting layer, the lowest LUMO (Lmin ) level among the ligands L1 to L3 of the dopant, and the constituent material of the cathode side adjacent layer of the light emitting layer There is provided an organic electroluminescence device characterized in that the relationship with the LUMO (C) level of the above satisfies the conditional expressions (i) and (ii).
少なくとも１層の発光層を有する有機エレクトロルミネッセンス素子であって、
前記発光層には、ホスト化合物と構造式Ｌ１Ｌ２Ｌ３Ｍ（Ｌ１～Ｌ３は二座配位子を表し、Ｍは中心金属を表す。）で表されるドーパントとが含有され、
前記ドーパントの配位子Ｌ１～Ｌ３のうち、少なくとも任意に選択した２つは異なっており、
前記発光層のホスト化合物のＬＵＭＯ（Ｈ）準位と、前記ドーパントの配位子Ｌ１～Ｌ３のうち最も低いＬＵＭＯ（Ｌｍｉｎ）準位と、前記発光層の陰極側隣接層の構成材料のＬＵＭＯ（Ｃ）準位との関係が、条件式（ｉ）および（ii）を満たすことを特徴とする有機エレクトロルミネッセンス素子が提供される。So, according to the present invention,
An organic electroluminescence device having at least one light emitting layer,
The light emitting layer contains a host compound and a dopant represented by the structural formula L1 L2 L3 M (where L1 to L3 represent a bidentate ligand and M represents a central metal). ,
Of the ligands L1 to L3 of the dopant, at least two arbitrarily selected are different,
The LUMO (H) level of the host compound of the light emitting layer, the lowest LUMO (Lmin ) level among the ligands L1 to L3 of the dopant, and the constituent material of the cathode side adjacent layer of the light emitting layer There is provided an organic electroluminescence device characterized in that the relationship with the LUMO (C) level of the above satisfies the conditional expressions (i) and (ii).
０＜ＬＵＭＯ（Ｌｍｉｎ）－ＬＵＭＯ（Ｈ）≦０．５ｅＶ・・・（ｉ）
ＬＵＭＯ（Ｈ）－０．５ｅＶ＜ＬＵＭＯ（Ｃ）＜ＬＵＭＯ（Ｌｍｉｎ）・・・（ii）0 <LUMO (Lmin ) −LUMO (H) ≦ 0.5 eV (i)
LUMO (H) −0.5 eV <LUMO (C) <LUMO (Lmin ) (ii)
ＬＵＭＯ（Ｈ）－０．５ｅＶ＜ＬＵＭＯ（Ｃ）＜ＬＵＭＯ（Ｌｍｉｎ）・・・（ii）0 <LUMO (Lmin ) −LUMO (H) ≦ 0.5 eV (i)
LUMO (H) −0.5 eV <LUMO (C) <LUMO (Lmin ) (ii)
本発明によれば、電圧上昇がなく、発光効率が高く、発光寿命を向上させた有機ＥＬ素子を提供することができる。According to the present invention, it is possible to provide an organic EL element that does not increase in voltage, has high luminous efficiency, and has improved luminous lifetime.
本発明者らは、上記目的を達成するために鋭意研究を重ねた結果、発光層にホスト化合物と構造式Ｌ１Ｌ２Ｌ３Ｍ（Ｌ１～Ｌ３は二座配位子を表し、Ｍは中心金属を表す。）で表されるドーパントとが含有され、ドーパントの配位子Ｌ１～Ｌ３のうち、少なくとも任意に選択した２つは異なっており、発光層のホスト化合物のＬＵＭＯ（Ｈ）準位と、ドーパントの配位子Ｌ１～Ｌ３のうち最も低いＬＵＭＯ（Ｌｍｉｎ）準位と、発光層の陰極側隣接層の構成材料のＬＵＭＯ（Ｃ）準位との関係が、条件式（ｉ）および（ii）を満たすことにより、電圧上昇がなく、発光効率が高く、寿命向上することが達成されることを見出し、本発明に至った。As a result of intensive studies to achieve the above object, the present inventors have found that the host compound and the structural formula L1 L2 L3 M (L1 to L3 represent bidentate ligands in the light emitting layer, M represents a central metal.), And at least two arbitrarily selected ligands L1 to L3 of the dopant are different, and the LUMO of the host compound of the light emitting layer is different. Relationship between (H) level, the lowest LUMO (Lmin ) level among the ligands L1 to L3 of the dopant, and the LUMO (C) level of the constituent material of the cathode side adjacent layer of the light emitting layer However, by satisfying conditional expressions (i) and (ii), it has been found that there is no increase in voltage, high luminous efficiency, and improvement in lifetime, and the present invention has been achieved.
０＜ＬＵＭＯ（Ｌｍｉｎ）－ＬＵＭＯ（Ｈ）≦０．５ｅＶ・・・（ｉ）
ＬＵＭＯ（Ｈ）－０．５ｅＶ＜ＬＵＭＯ（Ｃ）＜ＬＵＭＯ（Ｌｍｉｎ）・・・（ii）0 <LUMO (Lmin ) −LUMO (H) ≦ 0.5 eV (i)
LUMO (H) −0.5 eV <LUMO (C) <LUMO (Lmin ) (ii)
ＬＵＭＯ（Ｈ）－０．５ｅＶ＜ＬＵＭＯ（Ｃ）＜ＬＵＭＯ（Ｌｍｉｎ）・・・（ii）0 <LUMO (Lmin ) −LUMO (H) ≦ 0.5 eV (i)
LUMO (H) −0.5 eV <LUMO (C) <LUMO (Lmin ) (ii)
本発明の効果の発現機構・作用機構については明確になっていないが、以下のように推察している。The expression mechanism / action mechanism of the effect of the present invention is not clear, but is presumed as follows.
発光効率を低下させる原因として、発光層中のホスト化合物にドーパントを分散させた系では、ドーパントが高濃度である場合など、ドーパント同士が凝集することで、ＴＴ消滅（三重項－三重項消滅）してしまうことが一般的に知られている。
また、このような系においては、ドーパントが発光層中に均一に分散されにくく、ドーパント間の存在距離が遠くなる。その結果、ドーパントがキャリアの輸送を担う場合には、キャリアパスが不均一で乱れるため、電圧が上昇してしまう。また、ホスト化合物がキャリアの輸送を担う場合には、キャリアがドーパントに注入される確率が下がるため、再結合確率が低下し、発光効率が低下する。さらには、それに伴い発光寿命が低下する。In the system in which the dopant is dispersed in the host compound in the light emitting layer, the TT annihilation (triplet-triplet annihilation) is caused by the aggregation of the dopants when the dopant is in a high concentration. It is generally known that
Further, in such a system, the dopant is difficult to be uniformly dispersed in the light emitting layer, and the existence distance between the dopants is increased. As a result, when the dopant is responsible for carrier transport, the carrier path is uneven and disturbed, resulting in an increase in voltage. In addition, when the host compound is responsible for carrier transport, the probability of carriers being injected into the dopant is lowered, so the recombination probability is lowered and the light emission efficiency is lowered. Further, the light emission life is reduced accordingly.
また、このような系においては、ドーパントが発光層中に均一に分散されにくく、ドーパント間の存在距離が遠くなる。その結果、ドーパントがキャリアの輸送を担う場合には、キャリアパスが不均一で乱れるため、電圧が上昇してしまう。また、ホスト化合物がキャリアの輸送を担う場合には、キャリアがドーパントに注入される確率が下がるため、再結合確率が低下し、発光効率が低下する。さらには、それに伴い発光寿命が低下する。In the system in which the dopant is dispersed in the host compound in the light emitting layer, the TT annihilation (triplet-triplet annihilation) is caused by the aggregation of the dopants when the dopant is in a high concentration. It is generally known that
Further, in such a system, the dopant is difficult to be uniformly dispersed in the light emitting layer, and the existence distance between the dopants is increased. As a result, when the dopant is responsible for carrier transport, the carrier path is uneven and disturbed, resulting in an increase in voltage. In addition, when the host compound is responsible for carrier transport, the probability of carriers being injected into the dopant is lowered, so the recombination probability is lowered and the light emission efficiency is lowered. Further, the light emission life is reduced accordingly.
そのような中で、後述する一般式（１）で表されるドーパントを含有させることで、有機ＥＬ素子の発光効率、発光寿命を向上できることを明らかにしたものである。
すなわち、中心金属Ｍに配位する複数の配位子Ｌ１、Ｌ２、Ｌ３のうち、少なくとも任意に選択した２つの配位子構造を異ならせることで、ドーパント間の配位子同士の立体障害性が強くなり、ドーパント間の相互作用を緩和できることが分かった。
これにより、有機ＥＬ素子の発光層中のホスト化合物にドーパントを分散させる系では、ドーパント間の相互作用緩和により凝集状態が緩和され、その結果、ＴＴ消滅や再結合確率低下による発光効率低下や、キャリアパスが不均一で乱れることによる電圧上昇が抑制されるといった問題を解決でき、さらには発光寿命低下も解決できると考えている。Under such circumstances, it has been clarified that the light emission efficiency and the light emission lifetime of the organic EL element can be improved by containing a dopant represented by the general formula (1) described later.
That is, at least two arbitrarily selected ligand structures out of the plurality of ligands L1 , L2 , and L3 coordinated to the central metal M are made different between the ligands between the dopants. It was found that the steric hindrance becomes stronger and the interaction between the dopants can be relaxed.
Thereby, in the system in which the dopant is dispersed in the host compound in the light emitting layer of the organic EL element, the aggregation state is relaxed by relaxation of the interaction between the dopants. It is considered that the problem that the voltage rise due to the nonuniform and disturbed carrier path can be solved, and further the light emission lifetime can be reduced.
すなわち、中心金属Ｍに配位する複数の配位子Ｌ１、Ｌ２、Ｌ３のうち、少なくとも任意に選択した２つの配位子構造を異ならせることで、ドーパント間の配位子同士の立体障害性が強くなり、ドーパント間の相互作用を緩和できることが分かった。
これにより、有機ＥＬ素子の発光層中のホスト化合物にドーパントを分散させる系では、ドーパント間の相互作用緩和により凝集状態が緩和され、その結果、ＴＴ消滅や再結合確率低下による発光効率低下や、キャリアパスが不均一で乱れることによる電圧上昇が抑制されるといった問題を解決でき、さらには発光寿命低下も解決できると考えている。Under such circumstances, it has been clarified that the light emission efficiency and the light emission lifetime of the organic EL element can be improved by containing a dopant represented by the general formula (1) described later.
That is, at least two arbitrarily selected ligand structures out of the plurality of ligands L1 , L2 , and L3 coordinated to the central metal M are made different between the ligands between the dopants. It was found that the steric hindrance becomes stronger and the interaction between the dopants can be relaxed.
Thereby, in the system in which the dopant is dispersed in the host compound in the light emitting layer of the organic EL element, the aggregation state is relaxed by relaxation of the interaction between the dopants. It is considered that the problem that the voltage rise due to the nonuniform and disturbed carrier path can be solved, and further the light emission lifetime can be reduced.
加えて、本発明においては、ＬＵＭＯ準位が上記のように特定の序列となるように設計されているため、電子は陰極側隣接層から、ドーパントではなく、ホスト化合物へと障壁負荷なく注入され、かつ、発光層中の殆どを占めるホスト化合物上を負荷なく輸送されると予測される。すなわち、ドーパント－ドーパント間の電子輸送はされにくく、電子が注入されると即座に正孔と電子が再結合されると考えられる。結果として、正孔と電子が再結合する領域が、隣接層の界面近くではなく、発光層の中央部分となり、かつその領域が広くなるためと推測される。In addition, in the present invention, since the LUMO level is designed to have a specific order as described above, electrons are injected from the cathode-side adjacent layer into the host compound, not the dopant, without a barrier load. And, it is predicted that it is transported without load on the host compound occupying most of the light emitting layer. That is, it is considered that the electron transport between the dopant and the dopant is difficult, and when the electron is injected, the hole and the electron are immediately recombined. As a result, it is presumed that the region where holes and electrons recombine is not the vicinity of the interface between adjacent layers, but the central portion of the light emitting layer, and the region becomes wider.
また、一般的に、ホスト化合物よりドーパントのバンドギャップが狭くなるため、ＬＵＭＯ準位が特定の序列になるとき、基本的にドーパントが正孔の輸送を担うこととなる。ホスト化合物中にドーパントが均一に分散されているときには、正孔がスムーズにドーパント上を輸送されるため、正孔が陽極側隣接層（たとえば、正孔阻止層）側の界面よりも陰極側隣接層（たとえば、電子輸送層）側の界面により多く存在することになる。その際、ＬＵＭＯ準位を特定の序列とすれば、電子が陰極側隣接層側界面からドーパントに直接注入されず、ホスト化合物上を輸送されるため、再結合領域を陰極側隣接層界面だけでなく、全体に広げることができ、発光領域が広がり、発光効率を向上させることができる。In general, since the band gap of the dopant is narrower than that of the host compound, when the LUMO level is in a specific order, the dopant basically takes charge of transporting holes. When the dopant is uniformly dispersed in the host compound, the holes are smoothly transported on the dopant, so that the holes are adjacent to the cathode side than the interface on the anode side adjacent layer (for example, hole blocking layer) side. There will be more at the interface on the layer (eg, electron transport layer) side. At that time, if the LUMO level is in a specific order, electrons are not directly injected into the dopant from the cathode side adjacent layer side interface but are transported on the host compound, so that the recombination region is formed only at the cathode side adjacent layer interface. However, it is possible to expand the entire region, the light emitting region is expanded, and the light emission efficiency can be improved.
なお、本発明におけるＬＵＭＯ準位は、米国Ｇａｕｓｓｉａｎ社製の分子軌道計算用ソフトウェアであるＧａｕｓｓｉａｎ９８（Ｇａｕｓｓｉａｎ９８、Ｒｅｖｉｓｉｏｎ Ａ．１１．４，Ｍ．Ｊ．Ｆｒｉｓｃｈ，ｅｔ ａｌ，Ｇａｕｓｓｉａｎ，Ｉｎｃ．，Ｐｉｔｔｓｂｕｒｇｈ ＰＡ，２００２．）を用い、キーワードとしてＢ３ＬＹＰ／６－３１Ｇ＊を用いて構造最適化を行うことにより算出した値（ｅＶ単位換算値）の小数点第２位を四捨五入した値としてイオン化ポテンシャルを求めることにより算出することができる。この計算値が有効な背景には、この手法で求めた計算値と実験値の相関が高いためである。
本発明におけるドーパントの配位子のＬＵＭＯ準位は、金属に結合している部位を水素に置換した化合物のＬＵＭＯ準位として算出した値を用いた。The LUMO level in the present invention is Gaussian 98 (Gaussian 98, Revision A.11.4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, software for molecular orbital calculation manufactured by Gaussian, USA. 2002.), and by calculating the ionization potential as a value obtained by rounding off the second decimal place of the value (eV unit conversion value) calculated by performing structural optimization using B3LYP / 6-31G * as a keyword can do. This calculation value is effective because the correlation between the calculation value obtained by this method and the experimental value is high.
For the LUMO level of the dopant ligand in the present invention, the value calculated as the LUMO level of the compound in which the site bonded to the metal is replaced with hydrogen was used.
本発明におけるドーパントの配位子のＬＵＭＯ準位は、金属に結合している部位を水素に置換した化合物のＬＵＭＯ準位として算出した値を用いた。The LUMO level in the present invention is Gaussian 98 (Gaussian 98, Revision A.11.4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, software for molecular orbital calculation manufactured by Gaussian, USA. 2002.), and by calculating the ionization potential as a value obtained by rounding off the second decimal place of the value (eV unit conversion value) calculated by performing structural optimization using B3LYP / 6-31G * as a keyword can do. This calculation value is effective because the correlation between the calculation value obtained by this method and the experimental value is high.
For the LUMO level of the dopant ligand in the present invention, the value calculated as the LUMO level of the compound in which the site bonded to the metal is replaced with hydrogen was used.
また、ドーパントとして後述する一般式（２）～一般式（２－２）で表されるリン光ドーパントを用いることが、一般式（２）～一般式（２－２）におけるＲ１およびＲ２のいずれか一方が炭素数２以上の置換基であるため、よりドーパント間の立体障害性が強くなり、ドーパント間の相互作用を抑え、結果として、ドーパントの凝集状態を緩和することから好ましい。
また、ホスト化合物として後述する一般式（３）で表される化合物を本発明にかかるドーパントと組み合わせて用いるのがよい。In addition, it is possible to use phosphorescent dopants represented by general formula (2) to general formula (2-2) described later as dopants in R1 and R2 in general formula (2) to general formula (2-2). Since any one of these is a substituent having 2 or more carbon atoms, the steric hindrance between the dopants is further enhanced, the interaction between the dopants is suppressed, and as a result, the aggregation state of the dopants is relaxed, which is preferable.
Moreover, it is good to use the compound represented by General formula (3) mentioned later as a host compound in combination with the dopant concerning this invention.
また、ホスト化合物として後述する一般式（３）で表される化合物を本発明にかかるドーパントと組み合わせて用いるのがよい。In addition, it is possible to use phosphorescent dopants represented by general formula (2) to general formula (2-2) described later as dopants in R1 and R2 in general formula (2) to general formula (2-2). Since any one of these is a substituent having 2 or more carbon atoms, the steric hindrance between the dopants is further enhanced, the interaction between the dopants is suppressed, and as a result, the aggregation state of the dopants is relaxed, which is preferable.
Moreover, it is good to use the compound represented by General formula (3) mentioned later as a host compound in combination with the dopant concerning this invention.
また、発光層が少なくとも２層からなる場合、一般式（２）～一般式（２－２）で表されるドーパントを含む発光層に隣接する他の発光層に、上記ドーパントよりも長波長の発光を示すドーパントを含むことが、一般式（２）～一般式（２－２）で表されるドーパントが励起状態から基底状態に戻るときのエネルギーを長波長の発光を示すドーパントにエネルギー移動する割合より、一般式（２）～一般式（２－２）で表されるドーパントが発光するエネルギーとして利用される割合が多いため、効率よく発光し、寿命を向上する点から好ましい。In the case where the light emitting layer is composed of at least two layers, the other light emitting layer adjacent to the light emitting layer containing the dopant represented by the general formula (2) to the general formula (2-2) has a longer wavelength than the above dopant. The inclusion of a dopant exhibiting light emission transfers energy when the dopant represented by the general formulas (2) to (2-2) returns from the excited state to the ground state to the dopant exhibiting long wavelength light emission. From the ratio, the ratio of the dopant represented by the general formula (2) to the general formula (2-2) is more used as energy for light emission, which is preferable from the viewpoint of efficiently emitting light and improving the lifetime.
以下、本発明の好ましい実施形態について詳細に説明するが、本発明はこれらに限定されるものではない。Hereinafter, preferred embodiments of the present invention will be described in detail, but the present invention is not limited thereto.
《ドーパント（ヘテロドーパント）》
本発明にかかるドーパント（ヘテロドーパント）は、励起三重項からの発光が観測される化合物であり、具体的には室温（２５℃）にてリン光発光する化合物であり、リン光量子収率が、２５℃において０．０１以上の化合物であると定義されるが、好ましいリン光量子収率は０．１以上である。<< dopant (heterodopant) >>
The dopant (heterodopant) according to the present invention is a compound in which light emission from an excited triplet is observed, specifically, a compound that emits phosphorescence at room temperature (25 ° C.), and has a phosphorescence quantum yield of Although defined as a compound of 0.01 or more at 25 ° C., a preferred phosphorescence quantum yield is 0.1 or more.
本発明にかかるドーパント（ヘテロドーパント）は、励起三重項からの発光が観測される化合物であり、具体的には室温（２５℃）にてリン光発光する化合物であり、リン光量子収率が、２５℃において０．０１以上の化合物であると定義されるが、好ましいリン光量子収率は０．１以上である。<< dopant (heterodopant) >>
The dopant (heterodopant) according to the present invention is a compound in which light emission from an excited triplet is observed, specifically, a compound that emits phosphorescence at room temperature (25 ° C.), and has a phosphorescence quantum yield of Although defined as a compound of 0.01 or more at 25 ° C., a preferred phosphorescence quantum yield is 0.1 or more.
上記リン光量子収率は、第４版実験化学講座７の分光IIの３９８頁（１９９２年版、丸善）に記載の方法により測定できる。The phosphorescent quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of the Fourth Edition Experimental Chemistry Course 7.
リン光ドーパントの発光は原理としては２種挙げられ、１つはキャリアが輸送されるホスト化合物上でキャリアの再結合が起こって発光性ホスト化合物の励起状態が生成し、このエネルギーをリン光ドーパントに移動させることでリン光ドーパントからの発光を得るというエネルギー移動型、もう１つはリン光ドーパントがキャリアトラップとなり、リン光ドーパント上でキャリアの再結合が起こり、リン光ドーパントからの発光が得られるというキャリアトラップ型であるが、いずれの場合においても、リン光ドーパントの励起状態のエネルギーはホスト化合物の励起状態のエネルギーよりも低いことが条件である。There are two types of light emission of the phosphorescent dopant in principle. One is the recombination of carriers on the host compound to which carriers are transported to generate an excited state of the luminescent host compound, and this energy is used as the phosphorescent dopant. The energy transfer type is to obtain light emission from the phosphorescent dopant, and the other is that the phosphorescent dopant becomes a carrier trap, carrier recombination occurs on the phosphorescent dopant, and light emission from the phosphorescent dopant is obtained. In either case, the excited state energy of the phosphorescent dopant is required to be lower than the excited state energy of the host compound.
本発明のリン光ドーパントは、発光層の発光ホスト化合物中に分散された状態で、室温（２５℃）におけるリン光寿命が１．４μｓｅｃ未満かつ、リン光量子収率が７０％以上である。発光ホスト化合物中にリン光ドーパントが分散された膜のリン光寿命およびリン光量子収率は、石英ガラス上に発光ホスト化合物：リン光ドーパント＝９：１の比で４０ｎｍの厚みで共蒸着し、不活性ガス雰囲気下で封止した膜を用い、公知の方法で測定できる。The phosphorescent dopant of the present invention has a phosphorescence lifetime of less than 1.4 μsec at room temperature (25 ° C.) and a phosphorescence quantum yield of 70% or more when dispersed in the light emitting host compound of the light emitting layer. The phosphorescence lifetime and phosphorescence quantum yield of the film in which the phosphorescent dopant is dispersed in the luminescent host compound are co-deposited on the quartz glass at a ratio of luminescent host compound: phosphorescent dopant = 9: 1 at a thickness of 40 nm, Measurement can be performed by a known method using a film sealed in an inert gas atmosphere.
本発明にかかるドーパントは、青色リン光ドーパントであり、下記一般式（１）で表される。The dopant according to the present invention is a blue phosphorescent dopant and is represented by the following general formula (1).
式（１）中、「Ｌ１～Ｌ３」は二座配位子を表し、「Ｌ１～Ｌ３」のうち、少なくとも任意に選択した２つは異なっている。「Ｍ」は、中心金属を表す。In the formula (1), “L1 to L3 ” represents a bidentate ligand, and at least two arbitrarily selected among “L1 to L3 ” are different. “M” represents a central metal.
一般式（１）において、「Ｌ１～Ｌ３」で表される二座配位子としては、具体的には下記構造式で表される配位子等が挙げられる。In the general formula (1), specific examples of the bidentate ligand represented by “L1 to L3 ” include a ligand represented by the following structural formula.
上記配位子のＬＵＭＯ準位を表１に示す。Table 1 shows the LUMO levels of the above ligands.
上記一般式（１）の好ましい形態は、下記一般式（２）で表される。A preferred form of the general formula (1) is represented by the following general formula (2).
式（２）中、「環Ａ」および「環Ｂ」は、５員または６員の芳香族炭化水素環または芳香族複素環を表す。「Ａｒ」は、芳香族炭化水素環基、芳香族複素環基、非芳香族炭化水素環基または非芳香族複素環基を表す。「Ｒ１」および「Ｒ２」は、それぞれ独立に、水素原子または置換基を表し、「Ｒ１」および「Ｒ２」の少なくとも一方は、炭素原子数２以上のアルキル基またはシクロアルキル基である。「Ｒａ」，「Ｒｂ」および「Ｒｃ」は、それぞれ独立に、水素原子、ハロゲン原子、シアノ基、アルキル基、アルケニル基、アルキニル基、アルコキシ基、アミノ基、シリル基、アリールアルキル基、アリール基、ヘテロアリール基、非芳香族炭化水素環基または非芳香族複素環基を表す。ｎａおよびｎｃは１または２を表し、ｎｂは１～４の整数を表す。
「Ｌ′」は「Ｍ」に配位したモノアニオン性の二座配位子のうちの１つまたは複数であり、「Ｍ」は中心金属を表す。ｍ′は１または２の整数を表し、ｎ′は１または２の整数を表すが、ｍ′＋ｎ′は３である。「Ｌ′」は、異なる配位子である。In formula (2), “Ring A” and “Ring B” represent a 5- or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic ring. “Ar” represents an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group. “R1 ” and “R2 ” each independently represent a hydrogen atom or a substituent, and at least one of “R1 ” and “R2 ” is an alkyl group or cycloalkyl group having 2 or more carbon atoms. is there. "Ra", "Rb" and "Rc" are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group Represents a heteroaryl group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group. na andn c is 1 or 2,n b represents an integer of 1-4.
“L ′” is one or more of monoanionic bidentate ligands coordinated to “M”, and “M” represents a central metal. m ′ represents an integer of 1 or 2, n ′ represents an integer of 1 or 2, and m ′ + n ′ is 3. “L ′” is a different ligand.
「Ｌ′」は「Ｍ」に配位したモノアニオン性の二座配位子のうちの１つまたは複数であり、「Ｍ」は中心金属を表す。ｍ′は１または２の整数を表し、ｎ′は１または２の整数を表すが、ｍ′＋ｎ′は３である。「Ｌ′」は、異なる配位子である。In formula (2), “Ring A” and “Ring B” represent a 5- or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic ring. “Ar” represents an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group. “R1 ” and “R2 ” each independently represent a hydrogen atom or a substituent, and at least one of “R1 ” and “R2 ” is an alkyl group or cycloalkyl group having 2 or more carbon atoms. is there. "Ra", "Rb" and "Rc" are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group Represents a heteroaryl group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group. na andn c is 1 or 2,n b represents an integer of 1-4.
“L ′” is one or more of monoanionic bidentate ligands coordinated to “M”, and “M” represents a central metal. m ′ represents an integer of 1 or 2, n ′ represents an integer of 1 or 2, and m ′ + n ′ is 3. “L ′” is a different ligand.
「Ｒ１」および「Ｒ２」が置換基を表す場合、本発明にかかるドーパントの機能を阻害しない範囲で置換基を有してもよいことを意味し、そのような置換基としては、後述の「Ｒｄ’」，「Ｒｄ”」および「Ｒｄ’”」で表される置換基と同様のものが挙げられる。
「Ｒ１」および「Ｒ２」の少なくとも一方は、炭素原子数２以上のアルキル基またはシクロアルキル基を表すが、炭素原子数の上限としては、本発明にかかるドーパントの機能を阻害しない範囲であれば特に限定されず、好ましくは炭素原子数１０以下であり、さらに好ましくは６以下である。When “R1 ” and “R2 ” represent a substituent, it means that they may have a substituent as long as they do not impair the function of the dopant according to the present invention. And the same substituents represented by “Rd ′”, “Rd ″” and “Rd ′ ″”.
At least one of “R1 ” and “R2 ” represents an alkyl group or cycloalkyl group having 2 or more carbon atoms, and the upper limit of the number of carbon atoms is within a range not impairing the function of the dopant according to the present invention. If it is, it will not specifically limit, Preferably it is C10 or less, More preferably, it is 6 or less.
「Ｒ１」および「Ｒ２」の少なくとも一方は、炭素原子数２以上のアルキル基またはシクロアルキル基を表すが、炭素原子数の上限としては、本発明にかかるドーパントの機能を阻害しない範囲であれば特に限定されず、好ましくは炭素原子数１０以下であり、さらに好ましくは６以下である。When “R1 ” and “R2 ” represent a substituent, it means that they may have a substituent as long as they do not impair the function of the dopant according to the present invention. And the same substituents represented by “Rd ′”, “Rd ″” and “Rd ′ ″”.
At least one of “R1 ” and “R2 ” represents an alkyl group or cycloalkyl group having 2 or more carbon atoms, and the upper limit of the number of carbon atoms is within a range not impairing the function of the dopant according to the present invention. If it is, it will not specifically limit, Preferably it is C10 or less, More preferably, it is 6 or less.
「Ｒａ」，「Ｒｂ」および「Ｒｃ」で表される基は、本発明にかかるドーパントの機能を阻害しない範囲でさらに置換基を有していてもよく、そのような置換基としては、後述の「Ｒｄ’」，「Ｒｄ”」および「Ｒｄ’”」で表される置換基と同様のものが挙げられる。The groups represented by “Ra”, “Rb” and “Rc” may further have a substituent as long as they do not inhibit the function of the dopant according to the present invention. And the same substituents represented by “Rd ′”, “Rd ″” and “Rd ′ ″”.
上記一般式（２）の好ましい形態は、下記一般式（２－１）で表される。A preferred form of the general formula (2) is represented by the following general formula (2-1).
式（２－１）中、「Ａｒ」は芳香族炭化水素環基、芳香族複素環基、非芳香族炭化水素環基または非芳香族複素環基を表す。「Ｒ１」および「Ｒ２」は、それぞれ独立に、水素原子または置換基を表し、「Ｒ１」および「Ｒ２」の少なくとも一方は、炭素原子数２以上のアルキル基またはシクロアルキル基である。「Ｒａ」，「Ｒｂ」および「Ｒｃ」は、それぞれ独立に、水素原子、ハロゲン原子、シアノ基、アルキル基、アルケニル基、アルキニル基、アルコキシ基、アミノ基、シリル基、アリールアルキル基、アリール基、ヘテロアリール基、非芳香族炭化水素環基または非芳香族複素環基を表す。ｎａおよびｎｃは１または２を表し、ｎｂは１～４の整数を表す。
「Ｌ′」は「Ｍ」に配位したモノアニオン性の二座配位子のうちの１つまたは複数であり、「Ｍ」は中心金属を表す。ｍ′は１または２の整数を表し、ｎ′は１または２の整数を表すが、ｍ′＋ｎ′は３である。「Ｌ′」は、異なる配位子である。In the formula (2-1), “Ar” represents an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group. “R1 ” and “R2 ” each independently represent a hydrogen atom or a substituent, and at least one of “R1 ” and “R2 ” is an alkyl group or cycloalkyl group having 2 or more carbon atoms. is there. "Ra", "Rb" and "Rc" are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group Represents a heteroaryl group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group. na andn c is 1 or 2,n b represents an integer of 1-4.
“L ′” is one or more of monoanionic bidentate ligands coordinated to “M”, and “M” represents a central metal. m ′ represents an integer of 1 or 2, n ′ represents an integer of 1 or 2, and m ′ + n ′ is 3. “L ′” is a different ligand.
「Ｌ′」は「Ｍ」に配位したモノアニオン性の二座配位子のうちの１つまたは複数であり、「Ｍ」は中心金属を表す。ｍ′は１または２の整数を表し、ｎ′は１または２の整数を表すが、ｍ′＋ｎ′は３である。「Ｌ′」は、異なる配位子である。In the formula (2-1), “Ar” represents an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group. “R1 ” and “R2 ” each independently represent a hydrogen atom or a substituent, and at least one of “R1 ” and “R2 ” is an alkyl group or cycloalkyl group having 2 or more carbon atoms. is there. "Ra", "Rb" and "Rc" are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group Represents a heteroaryl group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group. na andn c is 1 or 2,n b represents an integer of 1-4.
“L ′” is one or more of monoanionic bidentate ligands coordinated to “M”, and “M” represents a central metal. m ′ represents an integer of 1 or 2, n ′ represents an integer of 1 or 2, and m ′ + n ′ is 3. “L ′” is a different ligand.
「Ｒ１」および「Ｒ２」が置換基を表す場合、本発明にかかるドーパントの機能を阻害しない範囲で置換基を有してもよいことを意味し、そのような置換基としては、後述の「Ｒｄ’」，「Ｒｄ”」および「Ｒｄ’”」で表される置換基と同様のものが挙げられる。
「Ｒ１」および「Ｒ２」の少なくとも一方は、炭素原子数２以上のアルキル基またはシクロアルキル基を表すが、炭素原子数の上限としては、本発明にかかるドーパントの機能を阻害しない範囲であれば特に限定されず、好ましくは炭素原子数１０以下であり、さらに好ましくは６以下である。When “R1 ” and “R2 ” represent a substituent, it means that they may have a substituent as long as they do not impair the function of the dopant according to the present invention. And the same substituents represented by “Rd ′”, “Rd ″” and “Rd ′ ″”.
At least one of “R1 ” and “R2 ” represents an alkyl group or cycloalkyl group having 2 or more carbon atoms, and the upper limit of the number of carbon atoms is within a range not impairing the function of the dopant according to the present invention. If it is, it will not specifically limit, Preferably it is C10 or less, More preferably, it is 6 or less.
「Ｒ１」および「Ｒ２」の少なくとも一方は、炭素原子数２以上のアルキル基またはシクロアルキル基を表すが、炭素原子数の上限としては、本発明にかかるドーパントの機能を阻害しない範囲であれば特に限定されず、好ましくは炭素原子数１０以下であり、さらに好ましくは６以下である。When “R1 ” and “R2 ” represent a substituent, it means that they may have a substituent as long as they do not impair the function of the dopant according to the present invention. And the same substituents represented by “Rd ′”, “Rd ″” and “Rd ′ ″”.
At least one of “R1 ” and “R2 ” represents an alkyl group or cycloalkyl group having 2 or more carbon atoms, and the upper limit of the number of carbon atoms is within a range not impairing the function of the dopant according to the present invention. If it is, it will not specifically limit, Preferably it is C10 or less, More preferably, it is 6 or less.
「Ｒａ」，「Ｒｂ」および「Ｒｃ」で表される基は、本発明にかかるドーパントの機能を阻害しない範囲でさらに置換基を有していてもよく、そのような置換基としては、後述の「Ｒｄ’」，「Ｒｄ”」および「Ｒｄ’”」で表される置換基と同様のものが挙げられる。The groups represented by “Ra”, “Rb” and “Rc” may further have a substituent as long as they do not inhibit the function of the dopant according to the present invention. And the same substituents represented by “Rd ′”, “Rd ″” and “Rd ′ ″”.
一般式（２）および（２－１）において、「Ｌ′」で表される「Ｍ」に配位したモノアニオン性の二座配位子の具体例としては、下記構造式で表される配位子等が挙げられる。In the general formulas (2) and (2-1), specific examples of the monoanionic bidentate ligand coordinated to “M” represented by “L ′” are represented by the following structural formulas. And a ligand.
式中、「Ｒｄ’」，「Ｒｄ”」および「Ｒｄ’”」は、それぞれ独立に、他の基との連結部位、水素原子または置換基を表し、各々の「Ｒｄ’」，「Ｒｄ”」，「Ｒｄ’”」は同じでも異なっていてもよく、また、「Ｒｄ’」，「Ｒｄ”」，「Ｒｄ’”」が互いに結合して環を形成してもよい。In the formula, “Rd ′”, “Rd ″” and “Rd ′ ″” each independently represent a linking site with another group, a hydrogen atom or a substituent, and each “Rd ′”, “Rd” ”And“ Rd ′ ″ ”may be the same or different, and“ Rd ′ ”,“ Rd ″ ”, and“ Rd ′ ″ ”may be bonded to each other to form a ring.
「Ｒｄ’」，「Ｒｄ”」および「Ｒｄ’”」が置換基を表す場合、本発明にかかるドーパントの機能を阻害しない範囲で置換基を有してもよいことを意味し、そのような置換基としては、たとえば、アルキル基（たとえば、メチル基、エチル基、プロピル基、イソプロピル基、ｔｅｒｔ－ブチル基、ペンチル基、ヘキシル基、オクチル基、ドデシル基、トリデシル基、テトラデシル基、ペンタデシル基等）、アルケニル基（たとえば、ビニル基、アリル基等）、アルキニル基（たとえば、エチニル基、プロパルギル基等）、非芳香族炭化水素環基（たとえば、シクロアルキル基（たとえば、シクロペンチル基、シクロヘキシル基等）、シクロアルコキシ基（たとえば、シクロペンチルオキシ基、シクロヘキシルオキシ基等）、シクロアルキルチオ基（たとえば、シクロペンチルチオ基、シクロヘキシルチオ基等）、テトラヒドロナフタレン環、９，１０－ジヒドロアントラセン環、ビフェニレン環等から導出される一価の基）、非芳香族複素環基（たとえば、エポキシ環、アジリジン環、チイラン環、オキセタン環、アゼチジン環、チエタン環、テトラヒドロフラン環、ジオキソラン環、ピロリジン環、ピラゾリジン環、イミダゾリジン環、オキサゾリジン環、テトラヒドロチオフェン環、スルホラン環、チアゾリジン環、ε－カプロラクトン環、ε－カプロラクタム環、ピペリジン環、ヘキサヒドロピリダジン環、ヘキサヒドロピリミジン環、ピペラジン環、モルホリン環、テトラヒドロピラン環、１，３－ジオキサン環、１，４－ジオキサン環、トリオキサン環、テトラヒドロチオピラン環、チオモルホリン環、チオモルホリン－１，１－ジオキシド環、ピラノース環、ジアザビシクロ［２，２，２］－オクタン環、フェノキサジン環、フェノチアジン環、オキサントレン環、チオキサンテン環、フェノキサチイン環等から導出される一価の基）、芳香族炭化水素基（たとえば、ベンゼン環、ビフェニル環、ナフタレン環、アズレン環、アントラセン環、フェナントレン環、ピレン環、クリセン環、ナフタセン環、トリフェニレン環、ｏ－テルフェニル環、ｍ－テルフェニル環、ｐ－テルフェニル環、アセナフテン環、コロネン環、フルオレン環、フルオラントレン環、ナフタセン環、ペンタセン環、ペリレン環、ペンタフェン環、ピセン環、ピレン環、ピラントレン環、アンスラアントレン環等から導出される一価の基）、芳香族複素環基（たとえば、シロール環、フラン環、チオフェン環、オキサゾール環、ピロール環、ピリジン環、ピリダジン環、ピリミジン環、ピラジン環、トリアジン環、オキサジアゾール環、トリアゾール環、イミダゾール環、ピラゾール環、チアゾール環、インドール環、ベンズイミダゾール環、ベンズチアゾール環、ベンズオキサゾール環、キノキサリン環、キナゾリン環、フタラジン環、チエノチオフェン環、カルバゾール環、アザカルバゾール環（カルバゾール環を構成する炭素原子の任意の一つ以上が窒素原子で置き換わったものを表す）、ジベンゾシロール環、ジベンゾフラン環、ジベンゾチオフェン環、ベンゾチオフェン環やジベンゾフラン環を構成する炭素原子の任意の一つ以上が窒素原子で置き換わった環、ベンゾジフラン環、ベンゾジチオフェン環、アクリジン環、ベンゾキノリン環、フェナジン環、フェナントリジン環、フェナントロリン環、サイクラジン環、キンドリン環、テペニジン環、キニンドリン環、トリフェノジチアジン環、トリフェノジオキサジン環、フェナントラジン環、アントラジン環、ペリミジン環、ナフトフラン環、ナフトチオフェン環、ナフトジフラン環、ナフトジチオフェン環、アントラフラン環、アントラジフラン環、アントラチオフェン環、アントラジチオフェン環、チアントレン環、フェノキサチイン環、ジベンゾカルバゾール環、インドロカルバゾール環、ジチエノベンゼン環等から導出される一価の基）、アルコキシ基（たとえば、メトキシ基、エトキシ基、プロピルオキシ基、ペンチルオキシ基、ヘキシルオキシ基、オクチルオキシ基、ドデシルオキシ基等）、アリールオキシ基（たとえば、フェノキシ基、ナフチルオキシ基等）、アルキルチオ基（たとえば、メチルチオ基、エチルチオ基、プロピルチオ基、ペンチルチオ基、ヘキシルチオ基、オクチルチオ基、ドデシルチオ基等）、アリールチオ基（たとえば、フェニルチオ基、ナフチルチオ基等）、アルコキシカルボニル基（たとえば、メチルオキシカルボニル基、エチルオキシカルボニル基、ブチルオキシカルボニル基、オクチルオキシカルボニル基、ドデシルオキシカルボニル基等）、アリールオキシカルボニル基（たとえば、フェニルオキシカルボニル基、ナフチルオキシカルボニル基等）、スルファモイル基（たとえば、アミノスルホニル基、メチルアミノスルホニル基、ジメチルアミノスルホニル基、ブチルアミノスルホニル基、ヘキシルアミノスルホニル基、シクロヘキシルアミノスルホニル基、オクチルアミノスルホニル基、ドデシルアミノスルホニル基、フェニルアミノスルホニル基、ナフチルアミノスルホニル基、２－ピリジルアミノスルホニル基等）、アシル基（たとえば、アセチル基、エチルカルボニル基、プロピルカルボニル基、ペンチルカルボニル基、シクロヘキシルカルボニル基、オクチルカルボニル基、２－エチルヘキシルカルボニル基、ドデシルカルボニル基、フェニルカルボニル基、ナフチルカルボニル基、ピリジルカルボニル基等）、アシルオキシ基（たとえば、アセチルオキシ基、エチルカルボニルオキシ基、ブチルカルボニルオキシ基、オクチルカルボニルオキシ基、ドデシルカルボニルオキシ基、フェニルカルボニルオキシ基等）、アミド基（たとえば、メチルカルボニルアミノ基、エチルカルボニルアミノ基、ジメチルカルボニルアミノ基、プロピルカルボニルアミノ基、ペンチルカルボニルアミノ基、シクロヘキシルカルボニルアミノ基、２－エチルヘキシルカルボニルアミノ基、オクチルカルボニルアミノ基、ドデシルカルボニルアミノ基、フェニルカルボニルアミノ基、ナフチルカルボニルアミノ基等）、カルバモイル基（たとえば、アミノカルボニル基、メチルアミノカルボニル基、ジメチルアミノカルボニル基、プロピルアミノカルボニル基、ペンチルアミノカルボニル基、シクロヘキシルアミノカルボニル基、オクチルアミノカルボニル基、２－エチルヘキシルアミノカルボニル基、ドデシルアミノカルボニル基、フェニルアミノカルボニル基、ナフチルアミノカルボニル基、２－ピリジルアミノカルボニル基等）、ウレイド基（たとえば、メチルウレイド基、エチルウレイド基、ペンチルウレイド基、シクロヘキシルウレイド基、オクチルウレイド基、ドデシルウレイド基、フェニルウレイド基、ナフチルウレイド基、２－ピリジルアミノウレイド基等）、スルフィニル基（たとえば、メチルスルフィニル基、エチルスルフィニル基、ブチルスルフィニル基、シクロヘキシルスルフィニル基、２－エチルヘキシルスルフィニル基、ドデシルスルフィニル基、フェニルスルフィニル基、ナフチルスルフィニル基、２－ピリジルスルフィニル基等）、アルキルスルホニル基（たとえば、メチルスルホニル基、エチルスルホニル基、ブチルスルホニル基、シクロヘキシルスルホニル基、２－エチルヘキシルスルホニル基、ドデシルスルホニル基等）、アリールスルホニル基またはヘテロアリールスルホニル基（たとえば、フェニルスルホニル基、ナフチルスルホニル基、２－ピリジルスルホニル基等）、アミノ基（たとえば、アミノ基、エチルアミノ基、ジメチルアミノ基、ブチルアミノ基、シクロペンチルアミノ基、２－エチルヘキシルアミノ基、ドデシルアミノ基、アニリノ基、ナフチルアミノ基、２－ピリジルアミノ基等）、ハロゲン原子（たとえば、フッ素原子、塩素原子、臭素原子、フッ化炭化水素基（たとえば、フルオロメチル基、トリフルオロメチル基、ペンタフルオロエチル基、ペンタフルオロフェニル基等）、シアノ基、ニトロ基、ヒドロキシ基、メルカプト基、シリル基（たとえば、トリメチルシリル基、トリイソプロピルシリル基、トリフェニルシリル基、フェニルジエチルシリル基等）、ホスホノ基等が挙げられる。When “Rd ′”, “Rd ″” and “Rd ′ ″” represent a substituent, it means that the substituent may be present as long as the function of the dopant according to the present invention is not impaired. Examples of the substituent include alkyl groups (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc. ), Alkenyl groups (eg, vinyl groups, allyl groups, etc.), alkynyl groups (eg, ethynyl groups, propargyl groups, etc.), non-aromatic hydrocarbon ring groups (eg, cycloalkyl groups (eg, cyclopentyl groups, cyclohexyl groups, etc.) ), A cycloalkoxy group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), cycloalkyl Thio group (for example, cyclopentylthio group, cyclohexylthio group, etc.), tetrahydronaphthalene ring, 9,10-dihydroanthracene ring, monovalent group derived from biphenylene ring, etc.), non-aromatic heterocyclic group (for example, epoxy Ring, aziridine ring, thiirane ring, oxetane ring, azetidine ring, thietane ring, tetrahydrofuran ring, dioxolane ring, pyrrolidine ring, pyrazolidine ring, imidazolidine ring, oxazolidine ring, tetrahydrothiophene ring, sulfolane ring, thiazolidine ring, ε-caprolactone ring , Ε-caprolactam ring, piperidine ring, hexahydropyridazine ring, hexahydropyrimidine ring, piperazine ring, morpholine ring, tetrahydropyran ring, 1,3-dioxane ring, 1,4-dioxane ring, trioxane ring, tetrahydro Opyran ring, thiomorpholine ring, thiomorpholine-1,1-dioxide ring, pyranose ring, diazabicyclo [2,2,2] -octane ring, phenoxazine ring, phenothiazine ring, oxanthrene ring, thioxanthene ring, phenoxathiin ring Monovalent groups derived from, etc.), aromatic hydrocarbon groups (for example, benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring, triphenylene ring, o -Terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, picene ring, pyrene ring, pyranthrene Monovalent derived from a ring, anthraanthrene ring, etc. Group), aromatic heterocyclic group (for example, silole ring, furan ring, thiophene ring, oxazole ring, pyrrole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, oxadiazole ring, triazole ring, imidazole Ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzthiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, thienothiophene ring, carbazole ring, azacarbazole ring (carbon atoms constituting carbazole ring) Any one or more of carbon atoms constituting a dibenzosilole ring, dibenzofuran ring, dibenzothiophene ring, benzothiophene ring or dibenzofuran ring is replaced with a nitrogen atom. Ring Nzodifuran ring, benzodithiophene ring, acridine ring, benzoquinoline ring, phenazine ring, phenanthridine ring, phenanthroline ring, cyclazine ring, kindrin ring, tepenidine ring, quinindrine ring, triphenodithiazine ring, triphenodioxazine ring, phenodine Nantrazine ring, anthrazine ring, perimidine ring, naphthofuran ring, naphthothiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring, anthrathiophene ring, anthradithiophene ring, thianthrene ring, phenoxathiin ring , A monovalent group derived from a dibenzocarbazole ring, an indolocarbazole ring, a dithienobenzene ring, etc.), an alkoxy group (eg, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyl) Xy group, octyloxy group, dodecyloxy group, etc.), aryloxy group (for example, phenoxy group, naphthyloxy group, etc.), alkylthio group (for example, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group) , Dodecylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.) ), Aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methylaminosulfonyl group, dimethyl) Minosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group ( For example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy Group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyl group) Oxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino) Group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylamino) Carbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl , Phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group) Group, naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthyl) Sulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, Chlorohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (eg, phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (eg, amino Group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc.), halogen atom (for example, fluorine atom, Chlorine atom, bromine atom, fluorinated hydrocarbon group (for example, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), cyano group, nitro group, hydroxy group, mercapto group, silyl group ( The For example, a trimethylsilyl group, a triisopropylsilyl group, a triphenylsilyl group, a phenyldiethylsilyl group), a phosphono group, and the like can be given.
一般式（２）および（２－１）において、「Ｍ」は中心金属を表し、たとえば、Ｏｓ、Ｉｒ、Ｐｔ等があげられる。In the general formulas (2) and (2-1), “M” represents a central metal, and examples thereof include Os, Ir, and Pt.
本発明にかかる一般式（２）および（２－１）で表される化合物は、国際公開第２００６－１２１８１１号等に記載の公知の方法を参照することにより合成可能である。The compounds represented by the general formulas (2) and (2-1) according to the present invention can be synthesized by referring to known methods described in International Publication No. 2006-121811, etc.
上記一般式（２－１）の好ましい形態は、下記一般式（２－２）で表される。A preferred form of the general formula (2-1) is represented by the following general formula (2-2).
式（２－２）中、「Ａｒ」は芳香族炭化水素環基、芳香族複素環基、非芳香族炭化水素環基または非芳香族複素環基を表す。「Ｒ１～Ｒ４」は、それぞれ独立に、水素原子または置換基を表し、「Ｒ１」および「Ｒ２」の少なくとも一方、「Ｒ３」および「Ｒ４」の少なくとも一方は、それぞれ炭素原子数２以上のアルキル基またはシクロアルキル基である。「Ｒａ」，「Ｒｂ」，「Ｒａ′」および「Ｒｂ′」は、それぞれ独立に、水素原子、ハロゲン原子、シアノ基、アルキル基、アルケニル基、アルキニル基、アルコキシ基、アミノ基、シリル基、アリールアルキル基、アリール基、ヘテロアリール基、非芳香族炭化水素環基または非芳香族複素環基を表す。ｎは、１または２の整数を表す。In the formula (2-2), “Ar” represents an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group. “R1 to R4 ” each independently represents a hydrogen atom or a substituent, and at least one of “R1 ” and “R2 ” and at least one of “R3 ” and “R4 ” are each carbon. An alkyl group or a cycloalkyl group having 2 or more atoms. “Ra”, “Rb”, “Ra ′” and “Rb ′” each independently represent a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, a silyl group, An arylalkyl group, an aryl group, a heteroaryl group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group is represented. n represents an integer of 1 or 2.
「Ｒ１」および「Ｒ２」の少なくとも一方、「Ｒ３」および「Ｒ４」の少なくとも一方は、炭素原子数２以上のアルキル基またはシクロアルキル基を表すが、炭素原子数の上限としては、本発明にかかるドーパントの機能を阻害しない範囲であれば特に限定されず、好ましくは炭素原子数１０以下であり、さらに好ましくは６以下である。At least one of “R1 ” and “R2 ” and at least one of “R3 ” and “R4 ” represents an alkyl group or cycloalkyl group having 2 or more carbon atoms, and the upper limit of the number of carbon atoms is The number of carbon atoms is not particularly limited as long as it does not hinder the function of the dopant according to the present invention, and it is preferably 10 or less, more preferably 6 or less.
「Ｒａ」，「Ｒｂ」，「Ｒａ′」および「Ｒｂ′」で表される基は、本発明にかかるドーパントの機能を阻害しない範囲でさらに置換基を有していてもよく、そのような置換基としては、前述の「Ｒｄ’」，「Ｒｄ”」および「Ｒｄ’”」で表される置換基と同様のものが挙げられる。The group represented by “Ra”, “Rb”, “Ra ′” and “Rb ′” may further have a substituent as long as the function of the dopant according to the present invention is not impaired. Examples of the substituent include the same substituents represented by the aforementioned “Rd ′”, “Rd ″” and “Rd ′ ″”.
以下に、本発明において、好ましく用いることのできる青色リン光ドーパントの具体例を挙げるが、本発明はこれらに限定されない。Hereinafter, specific examples of the blue phosphorescent dopant that can be preferably used in the present invention will be given, but the present invention is not limited thereto.
《ホスト化合物》
本発明において、発光層に用いられるホスト化合物は、発光層に含有される化合物の中で、その層中での質量比が２０％以上であり、かつ室温（２５℃）においてリン光発光のリン光量子収率が、０．１未満の化合物と定義される。
好ましくはリン光量子収率が０．０１未満である。《Host compound》
In the present invention, the host compound used in the light emitting layer is a phosphorescent phosphorous compound at a room temperature (25 ° C.) having a mass ratio of 20% or more among the compounds contained in the light emitting layer. A photon yield is defined as a compound of less than 0.1.
The phosphorescence quantum yield is preferably less than 0.01.
本発明において、発光層に用いられるホスト化合物は、発光層に含有される化合物の中で、その層中での質量比が２０％以上であり、かつ室温（２５℃）においてリン光発光のリン光量子収率が、０．１未満の化合物と定義される。
好ましくはリン光量子収率が０．０１未満である。《Host compound》
In the present invention, the host compound used in the light emitting layer is a phosphorescent phosphorous compound at a room temperature (25 ° C.) having a mass ratio of 20% or more among the compounds contained in the light emitting layer. A photon yield is defined as a compound of less than 0.1.
The phosphorescence quantum yield is preferably less than 0.01.
本発明に用いることができるホスト化合物としては、特に制限はなく、従来有機ＥＬ素子で用いられる化合物を用いることができるが、本発明の有機ＥＬ素子の発光層の青色リン光発光ドーパントに対するホスト化合物としては、特に下記一般式（３）で表される構造を有するものが好ましい。There is no restriction | limiting in particular as a host compound which can be used for this invention, Although the compound conventionally used with an organic EL element can be used, The host compound with respect to the blue phosphorescence emission dopant of the light emitting layer of the organic EL element of this invention In particular, those having a structure represented by the following general formula (3) are preferable.
式（３）中、「Ｘ」は、ＮＲ’，Ｏ，Ｓ，ＣＲ’Ｒ’’またはＳｉＲ’Ｒ’’を表す。「Ｒ１」は、フェニル基または芳香族複素環基を有するカルバゾリル基を表す。「Ｒ２」は、置換基を有してもよいカルバゾリル基を表す。Ｒ’およびＲ’’は、それぞれ独立に、水素原子または置換基を表す。In the formula (3), “X” represents NR ′, O, S, CR′R ″ or SiR′R ″. “R1 ” represents a carbazolyl group having a phenyl group or an aromatic heterocyclic group. “R2 ” represents a carbazolyl group which may have a substituent. R ′ and R ″ each independently represents a hydrogen atom or a substituent.
一般式（３）における「Ｘ」において、Ｒ’，Ｒ’’が置換基を表す場合、本発明にかかるホスト化合物としての機能を阻害しない範囲で置換基を有してもよいことを意味し、そのような置換基としては、アルキル基（たとえば、メチル基、エチル基、プロピル基、イソプロピル基、ｔ－ブチル基、ペンチル基、ヘキシル基、オクチル基、ドデシル基、トリデシル基、テトラデシル基、ペンタデシル基等）、シクロアルキル基（たとえば、シクロペンチル基、シクロヘキシル基等）、アルケニル基（たとえば、ビニル基、アリル基等）、アルキニル基（たとえば、エチニル基、プロパルギル基等）、芳香族炭化水素環基（芳香族炭素環基、アリール基等ともいい、たとえば、フェニル基、ｐ－クロロフェニル基、メシチル基、トリル基、キシリル基、ナフチル基、アントリル基、アズレニル基、アセナフテニル基、フルオレニル基、フェナントリル基、インデニル基、ピレニル基、ビフェニリル基等）、芳香族複素環基（たとえば、ピリジル基、ピリミジニル基、フリル基、ピロリル基、イミダゾリル基、ベンゾイミダゾリル基、ピラゾリル基、ピラジニル基、トリアゾリル基（たとえば、１，２，４－トリアゾール－１－イル基、１，２，３－トリアゾール－１－イル基等）、オキサゾリル基、ベンゾオキサゾリル基、チアゾリル基、イソオキサゾリル基、イソチアゾリル基、フラザニル基、チエニル基、キノリル基、ベンゾフリル基、ジベンゾフリル基、ベンゾチエニル基、ジベンゾチエニル基、インドリル基、カルバゾリル基、カルボリニル基、ジアザカルバゾリル基（前記カルボリニル基のカルボリン環を構成する炭素原子の一つが窒素原子で置き換わったものを示す）、キノキサリニル基、ピリダジニル基、トリアジニル基、キナゾリニル基、フタラジニル基等）、複素環基（たとえば、ピロリジル基、イミダゾリジル基、モルホリル基、オキサゾリジル基等）、アルコキシ基（たとえば、メトキシ基、エトキシ基、プロピルオキシ基、ペンチルオキシ基、ヘキシルオキシ基、オクチルオキシ基、ドデシルオキシ基等）、シクロアルコキシ基（たとえば、シクロペンチルオキシ基、シクロヘキシルオキシ基等）、アリールオキシ基（たとえば、フェノキシ基、ナフチルオキシ基等）、アルキルチオ基（たとえば、メチルチオ基、エチルチオ基、プロピルチオ基、ペンチルチオ基、ヘキシルチオ基、オクチルチオ基、ドデシルチオ基等）、シクロアルキルチオ基（たとえば、シクロペンチルチオ基、シクロヘキシルチオ基等）、アリールチオ基（たとえば、フェニルチオ基、ナフチルチオ基等）、アルコキシカルボニル基（たとえば、メチルオキシカルボニル基、エチルオキシカルボニル基、ブチルオキシカルボニル基、オクチルオキシカルボニル基、ドデシルオキシカルボニル基等）、アリールオキシカルボニル基（たとえば、フェニルオキシカルボニル基、ナフチルオキシカルボニル基等）、スルファモイル基（たとえば、アミノスルホニル基、メチルアミノスルホニル基、ジメチルアミノスルホニル基、ブチルアミノスルホニル基、ヘキシルアミノスルホニル基、シクロヘキシルアミノスルホニル基、オクチルアミノスルホニル基、ドデシルアミノスルホニル基、フェニルアミノスルホニル基、ナフチルアミノスルホニル基、２－ピリジルアミノスルホニル基等）、アシル基（たとえば、アセチル基、エチルカルボニル基、プロピルカルボニル基、ペンチルカルボニル基、シクロヘキシルカルボニル基、オクチルカルボニル基、２－エチルヘキシルカルボニル基、ドデシルカルボニル基、フェニルカルボニル基、ナフチルカルボニル基、ピリジルカルボニル基等）、アシルオキシ基（たとえば、アセチルオキシ基、エチルカルボニルオキシ基、ブチルカルボニルオキシ基、オクチルカルボニルオキシ基、ドデシルカルボニルオキシ基、フェニルカルボニルオキシ基等）、アミド基（たとえば、メチルカルボニルアミノ基、エチルカルボニルアミノ基、ジメチルカルボニルアミノ基、プロピルカルボニルアミノ基、ペンチルカルボニルアミノ基、シクロヘキシルカルボニルアミノ基、２－エチルヘキシルカルボニルアミノ基、オクチルカルボニルアミノ基、ドデシルカルボニルアミノ基、フェニルカルボニルアミノ基、ナフチルカルボニルアミノ基等）、カルバモイル基（たとえば、アミノカルボニル基、メチルアミノカルボニル基、ジメチルアミノカルボニル基、プロピルアミノカルボニル基、ペンチルアミノカルボニル基、シクロヘキシルアミノカルボニル基、オクチルアミノカルボニル基、２－エチルヘキシルアミノカルボニル基、ドデシルアミノカルボニル基、フェニルアミノカルボニル基、ナフチルアミノカルボニル基、２－ピリジルアミノカルボニル基等）、ウレイド基（たとえば、メチルウレイド基、エチルウレイド基、ペンチルウレイド基、シクロヘキシルウレイド基、オクチルウレイド基、ドデシルウレイド基、フェニルウレイド基ナフチルウレイド基、２－ピリジルアミノウレイド基等）、スルフィニル基（たとえば、メチルスルフィニル基、エチルスルフィニル基、ブチルスルフィニル基、シクロヘキシルスルフィニル基、２－エチルヘキシルスルフィニル基、ドデシルスルフィニル基、フェニルスルフィニル基、ナフチルスルフィニル基、２－ピリジルスルフィニル基等）、アルキルスルホニル基（たとえば、メチルスルホニル基、エチルスルホニル基、ブチルスルホニル基、シクロヘキシルスルホニル基、２－エチルヘキシルスルホニル基、ドデシルスルホニル基等）、アリールスルホニル基またはヘテロアリールスルホニル基（たとえば、フェニルスルホニル基、ナフチルスルホニル基、２－ピリジルスルホニル基等）、アミノ基（たとえば、アミノ基、エチルアミノ基、ジメチルアミノ基、ブチルアミノ基、シクロペンチルアミノ基、２－エチルヘキシルアミノ基、ドデシルアミノ基、アニリノ基、ナフチルアミノ基、２－ピリジルアミノ基等）、ハロゲン原子（たとえば、フッ素原子、塩素原子、臭素原子等）、フッ化炭化水素基（たとえば、フルオロメチル基、トリフルオロメチル基、ペンタフルオロエチル基、ペンタフルオロフェニル基等）、シアノ基、ニトロ基、ヒドロキシ基、メルカプト基、シリル基（たとえば、トリメチルシリル基、トリイソプロピルシリル基、トリフェニルシリル基、フェニルジエチルシリル基等）等が挙げられる。これらの置換基は、上記の置換基によってさらに置換されていてもよい。また、これらの置換基は、複数が互いに結合して環を形成していてもよい。In “X” in the general formula (3), when R ′ and R ″ represent a substituent, it means that the substituent may have a substituent as long as the function as a host compound according to the present invention is not impaired. Such substituents include alkyl groups (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group). Group), cycloalkyl group (eg cyclopentyl group, cyclohexyl group etc.), alkenyl group (eg vinyl group, allyl group etc.), alkynyl group (eg ethynyl group, propargyl group etc.), aromatic hydrocarbon ring group (Also called aromatic carbocyclic group, aryl group, etc., for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, Ryl group, naphthyl group, anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, biphenylyl group, etc.), aromatic heterocyclic group (for example, pyridyl group, pyrimidinyl group, furyl group, pyrrolyl) Group, imidazolyl group, benzoimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group (for example, 1,2,4-triazol-1-yl group, 1,2,3-triazol-1-yl group, etc.), oxazolyl group, Benzoxazolyl, thiazolyl, isoxazolyl, isothiazolyl, furazanyl, thienyl, quinolyl, benzofuryl, dibenzofuryl, benzothienyl, dibenzothienyl, indolyl, carbazolyl, carbolinyl, diaza Carbazolyl group (front One of the carbon atoms constituting the carboline ring of the carbolinyl group is replaced by a nitrogen atom), quinoxalinyl group, pyridazinyl group, triazinyl group, quinazolinyl group, phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imidazolidyl group) Group, morpholyl group, oxazolidyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (eg, cyclopentyl) Oxy group, cyclohexyloxy group, etc.), aryloxy group (for example, phenoxy group, naphthyloxy group, etc.), alkylthio group (for example, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group) Group, dodecylthio group, etc.), cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl, etc.) Group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methylaminosulfonyl) Group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylamino Sulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2 -Ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group) Group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, pro Rucarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, amino Carbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, Naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group) Group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group) Cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexyl) Sulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (for example, Sulfonylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, Anilino group, naphthylamino group, 2-pyridylamino group, etc.), halogen atom (eg fluorine atom, chlorine atom, bromine atom etc.), fluorinated hydrocarbon group (eg fluoromethyl group, trifluoromethyl group, pentafluoroethyl) Group, pentafluorophenyl group, etc.), cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.). These substituents may be further substituted with the above substituents. Further, these substituents may be bonded together to form a ring.
一般式（３）において、「Ｒ１」に含まれる芳香族複素環基として、たとえば、ピリジル基、ピリミジニル基、フリル基、ピロリル基、イミダゾリル基、ベンゾイミダゾリル基、ピラゾリル基、ピラジニル基、トリアゾリル基（たとえば、１，２，４－トリアゾール－１－イル基、１，２，３－トリアゾール－１－イル基等）、オキサゾリル基、ベンゾオキサゾリル基、チアゾリル基、イソオキサゾリル基、イソチアゾリル基、フラザニル基、チエニル基、キノリル基、ベンゾフリル基、ジベンゾフリル基、ベンゾチエニル基、ジベンゾチエニル基、インドリル基、カルバゾリル基、カルボリニル基、ジアザカルバゾリル基（前記カルボリニル基のカルボリン環を構成する炭素原子の一つが窒素原子で置き換わったものを示す）、キノキサリニル基、ピリダジニル基、トリアジニル基、キナゾリニル基、フタラジニル基等）等が挙げられる。In the general formula (3), examples of the aromatic heterocyclic group contained in “R1 ” include a pyridyl group, pyrimidinyl group, furyl group, pyrrolyl group, imidazolyl group, benzimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group ( For example, 1,2,4-triazol-1-yl group, 1,2,3-triazol-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group, furazanyl group , Thienyl group, quinolyl group, benzofuryl group, dibenzofuryl group, benzothienyl group, dibenzothienyl group, indolyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (the carbon atom constituting the carboline ring of the carbolinyl group) One is replaced by a nitrogen atom), quinoxa Group, pyridazinyl group, triazinyl group, quinazolinyl group and a phthalazinyl group) and the like.
一般式（３）において、「Ｒ２」で表されるカルバゾリル基が有してもよい置換基は、一般式（３）における「Ｘ」において、Ｒ’，Ｒ’’で各々表される置換基と同義である。In General Formula (3), the carbazolyl group represented by “R2 ” may have a substituent represented by R ′ and R ″ in “X” in General Formula (3). Synonymous with group.
中でも、「Ｘ」としては、ＮＲ’またはＯが好ましく、また、Ｒ’としては、芳香族炭化水素基（芳香族炭素環基、アリール基等ともいい、たとえば、フェニル基、ｐ－クロロフェニル基、メシチル基、トリル基、キシリル基、ナフチル基、アントリル基、アズレニル基、アセナフテニル基、フルオレニル基、フェナントリル基、インデニル基、ピレニル基、ビフェニリル基）、または芳香族複素環基（たとえば、フリル基、チエニル基、ピリジル基、ピリダジニル基、ピリミジニル基、ピラジニル基、トリアジニル基、イミダゾリル基、ピラゾリル基、チアゾリル基、キナゾリニル基、フタラジニル基等）が特に好ましい。Among them, “X” is preferably NR ′ or O, and R ′ is an aromatic hydrocarbon group (also referred to as an aromatic carbocyclic group, an aryl group, etc., for example, a phenyl group, a p-chlorophenyl group, Mesityl, tolyl, xylyl, naphthyl, anthryl, azulenyl, acenaphthenyl, fluorenyl, phenanthryl, indenyl, pyrenyl, biphenylyl) or aromatic heterocyclic groups (eg furyl, thienyl) Group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, phthalazinyl group and the like are particularly preferable.
上記の芳香族炭化水素基、芳香族複素環基は、各々一般式（３）の「Ｘ」において、Ｒ’，Ｒ’’で各々表される置換基を有してもよい。The above aromatic hydrocarbon group and aromatic heterocyclic group each may have a substituent represented by R ′ or R ″ in “X” of the general formula (3).
以下に、本発明において、好ましく用いることのできるホスト化合物の具体例を挙げるが、本発明はこれらに限定されない。Hereinafter, specific examples of host compounds that can be preferably used in the present invention will be given, but the present invention is not limited to these.
《緑色ドーパントおよび赤色ドーパント》
本発明にかかる緑色ドーパントおよび赤色ドーパントとしては、蛍光ドーパント（蛍光性化合物ともいう）、リン光ドーパント（リン光発光体、リン光性化合物、リン光発光性化合物等ともいう）を用いることができる。《Green dopant and red dopant》
As the green dopant and red dopant according to the present invention, fluorescent dopants (also referred to as fluorescent compounds) and phosphorescent dopants (also referred to as phosphorescent emitters, phosphorescent compounds, phosphorescent compounds, etc.) can be used. .
本発明にかかる緑色ドーパントおよび赤色ドーパントとしては、蛍光ドーパント（蛍光性化合物ともいう）、リン光ドーパント（リン光発光体、リン光性化合物、リン光発光性化合物等ともいう）を用いることができる。《Green dopant and red dopant》
As the green dopant and red dopant according to the present invention, fluorescent dopants (also referred to as fluorescent compounds) and phosphorescent dopants (also referred to as phosphorescent emitters, phosphorescent compounds, phosphorescent compounds, etc.) can be used. .
蛍光ドーパントとしては、クマリン系色素、ピラン系色素、シアニン系色素、クロコニウム系色素、スクアリウム系色素、オキソベンツアントラセン系色素、フルオレセイン系色素、ローダミン系色素、ピリリウム系色素、ペリレン系色素、スチルベン系色素、ポリチオフェン系色素、または希土類錯体系蛍光体等や、レーザー色素に代表される蛍光量子収率が高い化合物が挙げられるが、特にこれらに限定されるものではなく、有機ＥＬ素子の発光層に使用される公知のものの中から適宜選択して用いることができる。Fluorescent dopants include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes, stilbene dyes , Polythiophene dyes, rare earth complex phosphors, and the like, and compounds having a high fluorescence quantum yield, such as laser dyes, are not particularly limited, and are used for the light emitting layer of an organic EL device. It can select suitably from the well-known thing to be used.
リン光ドーパントとしては、好ましくは元素の周期表で８～１０族の金属を含有する錯体系化合物であり、さらに好ましくはイリジウム化合物、オスミウム化合物、または白金化合物（白金錯体系化合物）、希土類錯体であり、中でも最も好ましいのはイリジウム化合物である。The phosphorescent dopant is preferably a complex compound containing a group 8-10 metal in the periodic table of elements, more preferably an iridium compound, an osmium compound, a platinum compound (platinum complex compound), or a rare earth complex. Among them, the most preferable is an iridium compound.
本発明において、発光層が２層以上からなる場合、上記青色ドーパントを含む発光層に隣接する他の発光層に、青色ドーパントよりも長波長の発光を示すドーパントである緑色ドーパント、赤色ドーパントを含むことが好ましい。In this invention, when a light emitting layer consists of two or more layers, the other light emitting layer adjacent to the light emitting layer containing the said blue dopant contains the green dopant and red dopant which are dopants which show light emission longer wavelength than a blue dopant. It is preferable.
以下に、緑色ドーパントおよび赤色ドーパントとして用いられる化合物の具体例を示すが、本発明はこれらに限定されない。これらの化合物は、たとえば、Ｉｎｏｒｇ．Ｃｈｅｍ．４０巻、１７０４～１７１１に記載の方法等により合成できる。Specific examples of the compounds used as the green dopant and the red dopant are shown below, but the present invention is not limited to these. These compounds are described, for example, in Inorg. Chem. 40, 1704 to 1711, and the like.
以下、本発明の有機ＥＬ素子の各構成要素の詳細について、順次説明する。Hereinafter, details of each component of the organic EL element of the present invention will be sequentially described.
《有機ＥＬ素子の層構成》
本発明の有機ＥＬ素子の層構成の好ましい具体例を以下に示すが、本発明はこれらに限定されない。<< Layer structure of organic EL element >>
Although the preferable specific example of the layer structure of the organic EL element of this invention is shown below, this invention is not limited to these.
本発明の有機ＥＬ素子の層構成の好ましい具体例を以下に示すが、本発明はこれらに限定されない。<< Layer structure of organic EL element >>
Although the preferable specific example of the layer structure of the organic EL element of this invention is shown below, this invention is not limited to these.
（ｉ）陽極／発光層ユニット／電子輸送層／陰極
（ii）陽極／正孔輸送層／発光層ユニット／電子輸送層／陰極
（iii）陽極／正孔輸送層／発光層ユニット／正孔阻止層／電子輸送層／陰極
（iv）陽極／正孔輸送層／発光層ユニット／正孔阻止層／電子輸送層／電子注入層／陰極
（ｖ）陽極／正孔注入層／正孔輸送層／発光層ユニット／正孔阻止層／電子輸送層／電子注入層／陰極(I) Anode / light emitting layer unit / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer unit / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer unit / hole blocking Layer / electron transport layer / cathode (iv) anode / hole transport layer / light emitting layer unit / hole blocking layer / electron transport layer / electron injection layer / cathode (v) anode / hole injection layer / hole transport layer / Light emitting layer unit / hole blocking layer / electron transport layer / electron injection layer / cathode
（ii）陽極／正孔輸送層／発光層ユニット／電子輸送層／陰極
（iii）陽極／正孔輸送層／発光層ユニット／正孔阻止層／電子輸送層／陰極
（iv）陽極／正孔輸送層／発光層ユニット／正孔阻止層／電子輸送層／電子注入層／陰極
（ｖ）陽極／正孔注入層／正孔輸送層／発光層ユニット／正孔阻止層／電子輸送層／電子注入層／陰極(I) Anode / light emitting layer unit / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer unit / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer unit / hole blocking Layer / electron transport layer / cathode (iv) anode / hole transport layer / light emitting layer unit / hole blocking layer / electron transport layer / electron injection layer / cathode (v) anode / hole injection layer / hole transport layer / Light emitting layer unit / hole blocking layer / electron transport layer / electron injection layer / cathode
《発光層》
（１）特性
本発明にかかる発光層は、電極または電子輸送層、正孔輸送層から注入されてくる電子および正孔が再結合して発光する層である。
本発明にかかる発光層は、含まれる発光材料（ドーパント）が上記要件を満たしていれば、その構成には特に制限はない。
また、同一の発光スペクトルや発光極大波長を有する層が複数層あってもよい。
各発光層間には非発光性の中間層を有していることが好ましい。<Light emitting layer>
(1) Characteristics The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer.
If the light emitting material (dopant) contained in the light emitting layer concerning this invention satisfy | fills the said requirements, there will be no restriction | limiting in particular in the structure.
Moreover, there may be a plurality of layers having the same emission spectrum and emission maximum wavelength.
It is preferable to have a non-light emitting intermediate layer between each light emitting layer.
（１）特性
本発明にかかる発光層は、電極または電子輸送層、正孔輸送層から注入されてくる電子および正孔が再結合して発光する層である。
本発明にかかる発光層は、含まれる発光材料（ドーパント）が上記要件を満たしていれば、その構成には特に制限はない。
また、同一の発光スペクトルや発光極大波長を有する層が複数層あってもよい。
各発光層間には非発光性の中間層を有していることが好ましい。<Light emitting layer>
(1) Characteristics The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer.
If the light emitting material (dopant) contained in the light emitting layer concerning this invention satisfy | fills the said requirements, there will be no restriction | limiting in particular in the structure.
Moreover, there may be a plurality of layers having the same emission spectrum and emission maximum wavelength.
It is preferable to have a non-light emitting intermediate layer between each light emitting layer.
本発明における発光層の膜厚の総和は１～１００ｎｍの範囲にあることが好ましく、さらに好ましくは、より低い駆動電圧を得ることができることから３０ｎｍ以下である。なお、本発明でいうところの発光層の膜厚の総和とは、発光層間に非発光性の中間層が存在する場合には、当該中間層も含む膜厚である。
個々の発光層の膜厚としては１～５０ｎｍの範囲に調整することが好ましく、さらに好ましくは１～２０ｎｍの範囲に調整することである。青、緑、赤の各発光層の膜厚の関係については、特に制限はない。The total thickness of the light emitting layers in the present invention is preferably in the range of 1 to 100 nm, and more preferably 30 nm or less because a lower driving voltage can be obtained. In addition, the sum total of the film thickness of the light emitting layer as used in the field of this invention is a film thickness also including the said intermediate | middle layer, when a nonluminous intermediate | middle layer exists between light emitting layers.
The film thickness of each light emitting layer is preferably adjusted in the range of 1 to 50 nm, more preferably in the range of 1 to 20 nm. There is no particular limitation on the relationship between the film thicknesses of the blue, green and red light emitting layers.
個々の発光層の膜厚としては１～５０ｎｍの範囲に調整することが好ましく、さらに好ましくは１～２０ｎｍの範囲に調整することである。青、緑、赤の各発光層の膜厚の関係については、特に制限はない。The total thickness of the light emitting layers in the present invention is preferably in the range of 1 to 100 nm, and more preferably 30 nm or less because a lower driving voltage can be obtained. In addition, the sum total of the film thickness of the light emitting layer as used in the field of this invention is a film thickness also including the said intermediate | middle layer, when a nonluminous intermediate | middle layer exists between light emitting layers.
The film thickness of each light emitting layer is preferably adjusted in the range of 1 to 50 nm, more preferably in the range of 1 to 20 nm. There is no particular limitation on the relationship between the film thicknesses of the blue, green and red light emitting layers.
発光層の作製には、上記のホスト化合物や発光材料を、たとえば、真空蒸着法、スピンコート法、キャスト法、ＬＢ法、インクジェット法等の公知の薄膜化法により製膜して形成することができる。
本発明においては、各発光層には複数の発光材料を混合してもよく、またリン光発光材料と蛍光発光材料を同一発光層中に混合して用いてもよい。
本発明においては、発光層の構成として、ホスト化合物、ドーパントを含有し、ドーパントより発光させることが好ましい。For the production of the light-emitting layer, the above-described host compound or light-emitting material is formed by forming a film by a known thinning method such as a vacuum evaporation method, a spin coating method, a casting method, an LB method, or an inkjet method. it can.
In the present invention, a plurality of light emitting materials may be mixed in each light emitting layer, or a phosphorescent light emitting material and a fluorescent light emitting material may be mixed and used in the same light emitting layer.
In the present invention, the constitution of the light emitting layer preferably contains a host compound and a dopant and emits light from the dopant.
本発明においては、各発光層には複数の発光材料を混合してもよく、またリン光発光材料と蛍光発光材料を同一発光層中に混合して用いてもよい。
本発明においては、発光層の構成として、ホスト化合物、ドーパントを含有し、ドーパントより発光させることが好ましい。For the production of the light-emitting layer, the above-described host compound or light-emitting material is formed by forming a film by a known thinning method such as a vacuum evaporation method, a spin coating method, a casting method, an LB method, or an inkjet method. it can.
In the present invention, a plurality of light emitting materials may be mixed in each light emitting layer, or a phosphorescent light emitting material and a fluorescent light emitting material may be mixed and used in the same light emitting layer.
In the present invention, the constitution of the light emitting layer preferably contains a host compound and a dopant and emits light from the dopant.
（２）再結合領域
発光層全体の領域のうち、発光に寄与する領域（再結合領域）は、ΔＰＬ／ΔＥＬの値を算出してその算出結果から当該領域の広狭を推測することができる。
ΔＥＬ、ΔＰＬはそれぞれ駆動前後のエレクトロルミネッセンス（ＥＬ）、フォトルミネッセンス（ＰＬ）の強度減衰率を表し、以下の式で表すことができる。(2) Recombination region Of the entire region of the light emitting layer, the region contributing to light emission (recombination region) can be calculated from the value of ΔPL / ΔEL and the width of the region can be estimated from the calculation result.
ΔEL and ΔPL respectively represent the intensity decay rates of electroluminescence (EL) and photoluminescence (PL) before and after driving, and can be represented by the following equations.
発光層全体の領域のうち、発光に寄与する領域（再結合領域）は、ΔＰＬ／ΔＥＬの値を算出してその算出結果から当該領域の広狭を推測することができる。
ΔＥＬ、ΔＰＬはそれぞれ駆動前後のエレクトロルミネッセンス（ＥＬ）、フォトルミネッセンス（ＰＬ）の強度減衰率を表し、以下の式で表すことができる。(2) Recombination region Of the entire region of the light emitting layer, the region contributing to light emission (recombination region) can be calculated from the value of ΔPL / ΔEL and the width of the region can be estimated from the calculation result.
ΔEL and ΔPL respectively represent the intensity decay rates of electroluminescence (EL) and photoluminescence (PL) before and after driving, and can be represented by the following equations.
ΔＥＬ＝１－［ＥＬ（駆動後）／ＥＬ（駆動前）］
ΔＰＬ＝１－［ＰＬ（駆動後）／ＰＬ（駆動前）］ΔEL = 1− [EL (after driving) / EL (before driving)]
ΔPL = 1− [PL (after driving) / PL (before driving)]
ΔＰＬ＝１－［ＰＬ（駆動後）／ＰＬ（駆動前）］ΔEL = 1− [EL (after driving) / EL (before driving)]
ΔPL = 1− [PL (after driving) / PL (before driving)]
ＥＬ駆動では再結合領域でのみ発光が起きるのに対し、ＰＬ駆動では素子全体に光照射が行われるため発光は発光層の膜厚方向全体（層厚方向全体）で起きると考えられる。この測定条件として、ＰＬ駆動後のＰＬの値は、有機ＥＬ素子を、発光輝度が初期輝度から約半分になるまで駆動させた後（ΔＥＬが約０．５）の状態で測定する。ここで、ΔＰＬは発光層全体に対する再結合領域を表していることから、ΔＰＬ／ΔＥＬが小さい場合には発光に寄与する再結合領域が狭いと推測され、ΔＰＬ／ΔＥＬが大きい場合には発光に寄与する再結合領域が広いと推測される。In the EL drive, light emission occurs only in the recombination region, whereas in the PL drive, light irradiation is performed on the entire element, so that the light emission is considered to occur in the entire film thickness direction (layer thickness direction) of the light emitting layer. As a measurement condition, the PL value after the PL driving is measured in a state after driving the organic EL element until the light emission luminance is about half from the initial luminance (ΔEL is about 0.5). Here, since ΔPL represents a recombination region with respect to the entire light emitting layer, it is estimated that the recombination region contributing to light emission is narrow when ΔPL / ΔEL is small, and light emission occurs when ΔPL / ΔEL is large. It is presumed that the recombination region contributing is wide.
これらを模式的に説明すると下記のとおりである。
図１Ａ～１Ｄは発光層１における層厚方向の各領域を示す模式図であり、同図中の左右方向が層厚方向に対応している。
図１Ａに示すとおり、発光層１は、発光に寄与する領域（再結合領域１０）と、発光に寄与しない領域１２とに、区画される。
したがって、「駆動前のＥＬ」は再結合領域１０が測定対象となる。
他方、上記のとおり、ＰＬ駆動では素子全体に光照射がおこなわれるため、「駆動前のＰＬ」は、発光層全体を表す領域２０が測定対象となる。
その後、発光輝度が初期輝度からその約半分になるまでＥＬ駆動させると（ΔＥＬが約０．５）、図１Ｂに示すとおり、再結合領域１０中の約半分の領域で発光しなくなると考えられ、これを模式的に表現すると再結合領域１０中に非発光領域１６が形成されているように考えられる。
したがって、「駆動後のＥＬ」は、再結合領域１０から非発光領域１６を差し引いた領域１８が測定対象となる。
他方、「駆動後のＰＬ」は、再結合領域１０中に非発光領域１６が形成されたことに伴い、発光層全体を表す領域２０から非発光領域１６を差し引いた残りの領域２２が測定対象となる。These are schematically described as follows.
1A to 1D are schematic views showing respective regions in the layer thickness direction of thelight emitting layer 1, and the left-right direction in FIG. 1 corresponds to the layer thickness direction.
As shown in FIG. 1A, thelight emitting layer 1 is partitioned into a region contributing to light emission (recombination region 10) and aregion 12 not contributing to light emission.
Accordingly, therecombination region 10 is a measurement target for “EL before driving”.
On the other hand, as described above, in the PL driving, light irradiation is performed on the entire element. Therefore, “PL before driving” is the measurement target of theregion 20 representing the entire light emitting layer.
After that, when EL driving is performed until the light emission luminance is about half of the initial luminance (ΔEL is about 0.5), it is considered that light is not emitted in about half of therecombination region 10 as shown in FIG. 1B. When this is schematically expressed, it is considered that thenon-light emitting region 16 is formed in therecombination region 10.
Therefore, in “EL after driving”, aregion 18 obtained by subtracting thenon-light emitting region 16 from therecombination region 10 is a measurement target.
On the other hand, “PL after driving” indicates that the remainingregion 22 obtained by subtracting the non-light-emittingregion 16 from theregion 20 representing the entire light-emitting layer in accordance with the formation of the non-light-emittingregion 16 in therecombination region 10 is measured. It becomes.
図１Ａ～１Ｄは発光層１における層厚方向の各領域を示す模式図であり、同図中の左右方向が層厚方向に対応している。
図１Ａに示すとおり、発光層１は、発光に寄与する領域（再結合領域１０）と、発光に寄与しない領域１２とに、区画される。
したがって、「駆動前のＥＬ」は再結合領域１０が測定対象となる。
他方、上記のとおり、ＰＬ駆動では素子全体に光照射がおこなわれるため、「駆動前のＰＬ」は、発光層全体を表す領域２０が測定対象となる。
その後、発光輝度が初期輝度からその約半分になるまでＥＬ駆動させると（ΔＥＬが約０．５）、図１Ｂに示すとおり、再結合領域１０中の約半分の領域で発光しなくなると考えられ、これを模式的に表現すると再結合領域１０中に非発光領域１６が形成されているように考えられる。
したがって、「駆動後のＥＬ」は、再結合領域１０から非発光領域１６を差し引いた領域１８が測定対象となる。
他方、「駆動後のＰＬ」は、再結合領域１０中に非発光領域１６が形成されたことに伴い、発光層全体を表す領域２０から非発光領域１６を差し引いた残りの領域２２が測定対象となる。These are schematically described as follows.
1A to 1D are schematic views showing respective regions in the layer thickness direction of the
As shown in FIG. 1A, the
Accordingly, the
On the other hand, as described above, in the PL driving, light irradiation is performed on the entire element. Therefore, “PL before driving” is the measurement target of the
After that, when EL driving is performed until the light emission luminance is about half of the initial luminance (ΔEL is about 0.5), it is considered that light is not emitted in about half of the
Therefore, in “EL after driving”, a
On the other hand, “PL after driving” indicates that the remaining
ΔＰＬ／ΔＥＬが小さい場合、ΔＥＬが約０．５で固定されるため、「ΔＰＬ」が小さいことになる。ΔＰＬが小さい場合、「１－［ＰＬ（駆動後）／ＰＬ（駆動前）］」が小さいことになる。「１－［ＰＬ（駆動後）／ＰＬ（駆動前）］」が小さい場合、駆動前のＰＬは発光層全体の領域２０が測定対象となり固定されるため、「ＰＬ（駆動後）」が大きいことになる。ＰＬ（駆動後）が大きい場合、駆動後のＰＬは領域２２が測定対象となることから、領域２２の領域が広いことにつながる。
したがって、ΔＰＬ／ΔＥＬが小さい場合は領域２２の領域が広くなり、図１Ｃに示すとおり、もとの再結合領域１０は「狭い」と結論付けることができる。逆に、ΔＰＬ／ΔＥＬが大きい場合は領域２２の領域が狭くなり、図１Ｄに示すとおり、もとの再結合領域１０は「広い」と結論付けることができる。When ΔPL / ΔEL is small, since ΔEL is fixed at about 0.5, “ΔPL” is small. When ΔPL is small, “1− [PL (after driving) / PL (before driving)]” is small. When “1- [PL (after driving) / PL (before driving)]” is small, the PL before driving is fixed with theentire region 20 of the light emitting layer being measured, and thus “PL (after driving)” is large. It will be. When the PL (after driving) is large, theregion 22 becomes a measurement target in the PL after driving, which leads to awide area 22.
Therefore, when ΔPL / ΔEL is small, theregion 22 becomes wider, and it can be concluded that theoriginal recombination region 10 is “narrow” as shown in FIG. 1C. Conversely, when ΔPL / ΔEL is large, theregion 22 becomes narrow, and it can be concluded that theoriginal recombination region 10 is “wide” as shown in FIG. 1D.
したがって、ΔＰＬ／ΔＥＬが小さい場合は領域２２の領域が広くなり、図１Ｃに示すとおり、もとの再結合領域１０は「狭い」と結論付けることができる。逆に、ΔＰＬ／ΔＥＬが大きい場合は領域２２の領域が狭くなり、図１Ｄに示すとおり、もとの再結合領域１０は「広い」と結論付けることができる。When ΔPL / ΔEL is small, since ΔEL is fixed at about 0.5, “ΔPL” is small. When ΔPL is small, “1− [PL (after driving) / PL (before driving)]” is small. When “1- [PL (after driving) / PL (before driving)]” is small, the PL before driving is fixed with the
Therefore, when ΔPL / ΔEL is small, the
《注入層：電子注入層、正孔注入層》
注入層とは、駆動電圧低下や発光輝度向上のために電極と有機層間に設けられる層のことで、「有機ＥＬ素子とその工業化最前線（１９９８年１１月３０日エヌ・ティー・エス社発行）」の第２編第２章「電極材料」（１２３～１６６頁）に詳細に記載されており、正孔注入層（陽極バッファー層）と電子注入層（陰極バッファー層）とがある。
注入層は必要に応じて設けられ、上記のように陽極と発光層または正孔輸送層の間、および陰極と発光層または電子輸送層との間に存在させてもよい。<< Injection layer: electron injection layer, hole injection layer >>
An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).
The injection layer is provided as necessary, and may be present between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer as described above.
注入層とは、駆動電圧低下や発光輝度向上のために電極と有機層間に設けられる層のことで、「有機ＥＬ素子とその工業化最前線（１９９８年１１月３０日エヌ・ティー・エス社発行）」の第２編第２章「電極材料」（１２３～１６６頁）に詳細に記載されており、正孔注入層（陽極バッファー層）と電子注入層（陰極バッファー層）とがある。
注入層は必要に応じて設けられ、上記のように陽極と発光層または正孔輸送層の間、および陰極と発光層または電子輸送層との間に存在させてもよい。<< Injection layer: electron injection layer, hole injection layer >>
An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).
The injection layer is provided as necessary, and may be present between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer as described above.
正孔注入層（陽極バッファー層）は、特開平９－４５４７９号公報、同９－２６００６２号公報、同８－２８８０６９号公報等にもその詳細が記載されており、具体例として、銅フタロシアニンに代表されるフタロシアニンバッファー層、酸化バナジウムに代表される酸化物バッファー層、アモルファスカーボンバッファー層、ポリアニリン（エメラルディン）やポリチオフェン等の導電性高分子を用いた高分子バッファー層等が挙げられる。The details of the hole injection layer (anode buffer layer) are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069, and the like. As a specific example, copper phthalocyanine is used. Examples thereof include a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.
電子注入層（陰極バッファー層）は、特開平６－３２５８７１号公報、同９－１７５７４号公報、同１０－７４５８６号公報等にもその詳細が記載されており、具体的にはストロンチウムやアルミニウム等に代表される金属バッファー層、フッ化リチウムに代表されるアルカリ金属化合物バッファー層、フッ化マグネシウムに代表されるアルカリ土類金属化合物バッファー層、酸化アルミニウムに代表される酸化物バッファー層等が挙げられる。Details of the electron injection layer (cathode buffer layer) are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Metal buffer layer typified by lithium, alkali metal compound buffer layer typified by lithium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, oxide buffer layer typified by aluminum oxide, etc. .
上記注入層はごく薄い膜であることが望ましく、素材にもよるがその膜厚は０．１ｎｍ～５μｍの範囲が好ましい。The injection layer is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm although it depends on the material.
《阻止層：正孔阻止層、電子阻止層》
阻止層は、上記のように有機化合物薄膜の基本構成層の他に必要に応じて設けられるものである。たとえば、特開平１１－２０４２５８号公報、同１１－２０４３５９号公報、および「有機ＥＬ素子とその工業化最前線（１９９８年１１月３０日エヌ・ティー・エス社発行）」の２３７頁等に記載されている正孔阻止（ホールブロック）層がある。<Blocking layer: hole blocking layer, electron blocking layer>
The blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film as described above. For example, it is described in JP-A Nos. 11-204258 and 11-204359, and “Organic EL elements and the forefront of industrialization (published by NTT Corporation on Nov. 30, 1998)”. There is a hole blocking (hole blocking) layer.
阻止層は、上記のように有機化合物薄膜の基本構成層の他に必要に応じて設けられるものである。たとえば、特開平１１－２０４２５８号公報、同１１－２０４３５９号公報、および「有機ＥＬ素子とその工業化最前線（１９９８年１１月３０日エヌ・ティー・エス社発行）」の２３７頁等に記載されている正孔阻止（ホールブロック）層がある。<Blocking layer: hole blocking layer, electron blocking layer>
The blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film as described above. For example, it is described in JP-A Nos. 11-204258 and 11-204359, and “Organic EL elements and the forefront of industrialization (published by NTT Corporation on Nov. 30, 1998)”. There is a hole blocking (hole blocking) layer.
正孔阻止層とは、広い意味では電子輸送層の機能を有し、電子を輸送する機能を有しつつ正孔を輸送する能力が著しく小さい正孔阻止材料からなり、電子を輸送しつつ正孔を阻止することで電子と正孔の再結合確率を向上させることができる。また、後述する電子輸送層の構成を必要に応じて、本発明にかかる正孔阻止層として用いることができる。The hole blocking layer has a function of an electron transport layer in a broad sense, and is made of a hole blocking material having a function of transporting electrons and a very small ability to transport holes. By blocking the holes, the probability of recombination of electrons and holes can be improved. Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer concerning this invention as needed.
本発明の有機ＥＬ素子の正孔阻止層は、発光層に隣接して設けられていることが好ましい。The hole blocking layer of the organic EL device of the present invention is preferably provided adjacent to the light emitting layer.
正孔阻止層には、アザカルバゾール誘導体を含有することが好ましい。The hole blocking layer preferably contains an azacarbazole derivative.
また、本発明においては、複数の発光色の異なる複数の発光層を有する場合、その発光極大波長が最も短波にある発光層が、全発光層中、最も陽極に近いことが好ましいが、このような場合、該最短波層と該層の次に陽極に近い発光層との間に正孔阻止層を追加して設けることが好ましい。さらには、該位置に設けられる正孔阻止層に含有される化合物の５０質量％以上が、最短波発光層のホスト化合物に対しそのイオン化ポテンシャルが０．３ｅＶ以上大きいことが好ましい。In the present invention, when a plurality of light emitting layers having different light emission colors are provided, the light emitting layer having the shortest wavelength of light emission is preferably closest to the anode among all the light emitting layers. In this case, it is preferable to additionally provide a hole blocking layer between the shortest wave layer and the light emitting layer next to the anode next to the anode. Furthermore, it is preferable that 50% by mass or more of the compound contained in the hole blocking layer provided at the position has an ionization potential of 0.3 eV or more larger than the host compound of the shortest wave emitting layer.
イオン化ポテンシャルは化合物のＨＯＭＯ（最高被占分子軌道）レベルにある電子を真空準位に放出するのに必要なエネルギーで定義され、たとえば下記（１），（２）に示すような方法により求めることができる。The ionization potential is defined by the energy required to emit electrons at the HOMO (highest occupied molecular orbital) level of the compound to the vacuum level. For example, the ionization potential is obtained by the method shown in (1) and (2) below. Can do.
（１）分子軌道計算
米国Ｇａｕｓｓｉａｎ社製の分子軌道計算用ソフトウェアであるＧａｕｓｓｉａｎ９８（Ｇａｕｓｓｉａｎ９８、Ｒｅｖｉｓｉｏｎ Ａ．１１．４，Ｍ．Ｊ．Ｆｒｉｓｃｈ，ｅｔ ａｌ，Ｇａｕｓｓｉａｎ，Ｉｎｃ．，Ｐｉｔｔｓｂｕｒｇｈ ＰＡ，２００２．）を用い、キーワードとしてＢ３ＬＹＰ／６－３１Ｇ＊を用いて構造最適化を行うことにより算出した値（ｅＶ単位換算値）の小数点第２位を四捨五入した値としてイオン化ポテンシャルを求めることができる。この計算値が有効な背景には、この手法で求めた計算値と実験値の相関が高いためである。(1) Molecular orbital calculation Gaussian98 (Gaussian98, Revision A.11.4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, 2002.), which is software for molecular orbital calculation manufactured by Gaussian, USA. The ionization potential can be obtained as a value obtained by rounding off the second decimal place of a value (eV unit converted value) calculated by performing structure optimization using B3LYP / 6-31G * as a keyword. This calculation value is effective because the correlation between the calculation value obtained by this method and the experimental value is high.
米国Ｇａｕｓｓｉａｎ社製の分子軌道計算用ソフトウェアであるＧａｕｓｓｉａｎ９８（Ｇａｕｓｓｉａｎ９８、Ｒｅｖｉｓｉｏｎ Ａ．１１．４，Ｍ．Ｊ．Ｆｒｉｓｃｈ，ｅｔ ａｌ，Ｇａｕｓｓｉａｎ，Ｉｎｃ．，Ｐｉｔｔｓｂｕｒｇｈ ＰＡ，２００２．）を用い、キーワードとしてＢ３ＬＹＰ／６－３１Ｇ＊を用いて構造最適化を行うことにより算出した値（ｅＶ単位換算値）の小数点第２位を四捨五入した値としてイオン化ポテンシャルを求めることができる。この計算値が有効な背景には、この手法で求めた計算値と実験値の相関が高いためである。(1) Molecular orbital calculation Gaussian98 (Gaussian98, Revision A.11.4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, 2002.), which is software for molecular orbital calculation manufactured by Gaussian, USA. The ionization potential can be obtained as a value obtained by rounding off the second decimal place of a value (eV unit converted value) calculated by performing structure optimization using B3LYP / 6-31G * as a keyword. This calculation value is effective because the correlation between the calculation value obtained by this method and the experimental value is high.
（２）光電子分光法
イオン化ポテンシャルは光電子分光法で直接測定する方法により求めることもできる。たとえば、理研計器社製の低エネルギー電子分光装置「Ｍｏｄｅｌ ＡＣ－１」を用いて、あるいは紫外光電子分光として知られている方法を好適に用いることができる。(2) Photoelectron spectroscopy The ionization potential can also be obtained by a method of direct measurement by photoelectron spectroscopy. For example, a low energy electron spectrometer “Model AC-1” manufactured by Riken Keiki Co., Ltd. or a method known as ultraviolet photoelectron spectroscopy can be suitably used.
イオン化ポテンシャルは光電子分光法で直接測定する方法により求めることもできる。たとえば、理研計器社製の低エネルギー電子分光装置「Ｍｏｄｅｌ ＡＣ－１」を用いて、あるいは紫外光電子分光として知られている方法を好適に用いることができる。(2) Photoelectron spectroscopy The ionization potential can also be obtained by a method of direct measurement by photoelectron spectroscopy. For example, a low energy electron spectrometer “Model AC-1” manufactured by Riken Keiki Co., Ltd. or a method known as ultraviolet photoelectron spectroscopy can be suitably used.
一方、電子阻止層とは、広い意味では正孔輸送層の機能を有し、正孔を輸送する機能を有しつつ電子を輸送する能力が著しく小さい材料からなり、正孔を輸送しつつ電子を阻止することで電子と正孔の再結合確率を向上させることができる。また、後述する正孔輸送層の構成を必要に応じて電子阻止層として用いることができる。
本発明にかかる正孔阻止層、電子輸送層の膜厚としては、好ましくは３ｎｍ～１００ｎｍであり、さらに好ましくは５ｎｍ～３０ｎｍである。On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense, and is made of a material having a function of transporting holes while having a remarkably small ability to transport electrons. The probability of recombination of electrons and holes can be improved by blocking. Moreover, the structure of the positive hole transport layer mentioned later can be used as an electron blocking layer as needed.
The film thickness of the hole blocking layer and the electron transport layer according to the present invention is preferably 3 nm to 100 nm, more preferably 5 nm to 30 nm.
本発明にかかる正孔阻止層、電子輸送層の膜厚としては、好ましくは３ｎｍ～１００ｎｍであり、さらに好ましくは５ｎｍ～３０ｎｍである。On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense, and is made of a material having a function of transporting holes while having a remarkably small ability to transport electrons. The probability of recombination of electrons and holes can be improved by blocking. Moreover, the structure of the positive hole transport layer mentioned later can be used as an electron blocking layer as needed.
The film thickness of the hole blocking layer and the electron transport layer according to the present invention is preferably 3 nm to 100 nm, more preferably 5 nm to 30 nm.
《正孔輸送層》
正孔輸送層とは、正孔を輸送する機能を有する正孔輸送材料からなり、広い意味で正孔注入層、電子阻止層も正孔輸送層に含まれる。正孔輸送層は、単層または複数層設けることができる。《Hole transport layer》
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.
正孔輸送層とは、正孔を輸送する機能を有する正孔輸送材料からなり、広い意味で正孔注入層、電子阻止層も正孔輸送層に含まれる。正孔輸送層は、単層または複数層設けることができる。《Hole transport layer》
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.
正孔輸送材料としては、正孔の注入または輸送、電子の障壁性のいずれかを有するものであり、有機物、無機物のいずれであってもよい。たとえば、トリアゾール誘導体、オキサジアゾール誘導体、イミダゾール誘導体、ポリアリールアルカン誘導体、ピラゾリン誘導体およびピラゾロン誘導体、フェニレンジアミン誘導体、アリールアミン誘導体、アミノ置換カルコン誘導体、オキサゾール誘導体、スチリルアントラセン誘導体、フルオレノン誘導体、ヒドラゾン誘導体、スチルベン誘導体、シラザン誘導体、アニリン系共重合体、また導電性高分子オリゴマー、特にチオフェンオリゴマー等が挙げられる。
正孔輸送材料としては上記のものを使用することができるが、ポルフィリン化合物、芳香族第３級アミン化合物およびスチリルアミン化合物、特に芳香族第３級アミン化合物を用いることが好ましい。The hole transport material has any one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.
The above-mentioned materials can be used as the hole transport material, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.
正孔輸送材料としては上記のものを使用することができるが、ポルフィリン化合物、芳香族第３級アミン化合物およびスチリルアミン化合物、特に芳香族第３級アミン化合物を用いることが好ましい。The hole transport material has any one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.
The above-mentioned materials can be used as the hole transport material, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.
芳香族第３級アミン化合物およびスチリルアミン化合物の代表例としては、Ｎ，Ｎ，Ｎ′，Ｎ′－テトラフェニル－４，４′－ジアミノフェニル；Ｎ，Ｎ′－ジフェニル－Ｎ，Ｎ′－ビス（３－メチルフェニル）－〔１，１′－ビフェニル〕－４，４′－ジアミン（ＴＰＤ）；２，２－ビス（４－ジ－ｐ－トリルアミノフェニル）プロパン；１，１－ビス（４－ジ－ｐ－トリルアミノフェニル）シクロヘキサン；Ｎ，Ｎ，Ｎ′，Ｎ′－テトラ－ｐ－トリル－４，４′－ジアミノビフェニル；１，１－ビス（４－ジ－ｐ－トリルアミノフェニル）－４－フェニルシクロヘキサン；ビス（４－ジメチルアミノ－２－メチルフェニル）フェニルメタン；ビス（４－ジ－ｐ－トリルアミノフェニル）フェニルメタン；Ｎ，Ｎ′－ジフェニル－Ｎ，Ｎ′－ジ（４－メトキシフェニル）－４，４′－ジアミノビフェニル；Ｎ，Ｎ，Ｎ′，Ｎ′－テトラフェニル－４，４′－ジアミノジフェニルエーテル；４，４′－ビス（ジフェニルアミノ）クオードリフェニル；Ｎ，Ｎ，Ｎ－トリ（ｐ－トリル）アミン；４－（ジ－ｐ－トリルアミノ）－４′－〔４－（ジ－ｐ－トリルアミノ）スチリル〕スチルベン；４－Ｎ，Ｎ－ジフェニルアミノ－（２－ジフェニルビニル）ベンゼン；３－メトキシ－４′－Ｎ，Ｎ－ジフェニルアミノスチルベンゼン；Ｎ－フェニルカルバゾール、さらには米国特許第５，０６１，５６９号明細書に記載されている２個の縮合芳香族環を分子内に有するもの、たとえば、４，４′－ビス〔Ｎ－（１－ナフチル）－Ｎ－フェニルアミノ〕ビフェニル（ＮＰＤ）、特開平４－３０８６８８号公報に記載されているトリフェニルアミンユニットが３つスターバースト型に連結された４，４′，４″－トリス〔Ｎ－（３－メチルフェニル）－Ｎ－フェニルアミノ〕トリフェニルアミン（ＭＴＤＡＴＡ）等が挙げられる。Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′— Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N -Di (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadri N; N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenyl Amino- (2-diphenylvinyl) benzene; 3-methoxy-4′-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and further described in US Pat. No. 5,061,569 Having four condensed aromatic rings in the molecule, such as 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 08688 are linked in a starburst type ( MTDATA) and the like.
さらに、これらの材料を高分子鎖に導入した、またはこれらの材料を高分子の主鎖とした高分子材料を用いることもできる。また、ｐ型－Ｓｉ、ｐ型－ＳｉＣ等の無機化合物も正孔注入材料、正孔輸送材料として使用することができる。Furthermore, polymer materials in which these materials are introduced into polymer chains or these materials are used as polymer main chains can also be used. In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.
また、特開平１１－２５１０６７号公報、Ｊ．Ｈｕａｎｇ ｅｔ．ａｌ．著文献（Ａｐｐｌｉｅｄ Ｐｈｙｓｉｃｓ Ｌｅｔｔｅｒｓ ８０（２００２），ｐ．１３９）に記載されているような、所謂ｐ型正孔輸送材料を用いることもできる。本発明においては、より高効率の発光素子が得られることからこれらの材料を用いることが好ましい。Also, JP-A-11-251067, J. Org. Huang et. al. A so-called p-type hole transport material described in a book (Applied Physics Letters 80 (2002), p. 139) can also be used. In the present invention, these materials are preferably used because a light-emitting element with higher efficiency can be obtained.
正孔輸送層は、上記正孔輸送材料を、たとえば、真空蒸着法、スピンコート法、キャスト法、インクジェット法を含む印刷法、ＬＢ法等の公知の方法により、薄膜化することにより形成することができる。正孔輸送層の膜厚については特に制限はないが、通常は５ｎｍ～５μｍ程度、好ましくは５ｎｍ～２００ｎｍである。この正孔輸送層は上記材料の１種または２種以上からなる一層構造であってもよい。The hole transport layer is formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Can do. The thickness of the hole transport layer is not particularly limited, but is usually about 5 nm to 5 μm, preferably 5 nm to 200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.
また、不純物をドープしたｐ性の高い正孔輸送層を用いることもできる。その例としては、特開平４－２９７０７６号公報、特開２０００－１９６１４０号公報、同２００１－１０２１７５号公報の各公報、Ｊ．Ａｐｐｌ．Ｐｈｙｓ．，９５，５７７３（２００４）等に記載されたものが挙げられる。
本発明においては、このようなｐ性の高い正孔輸送層を用いることが、より低消費電力の素子を作製することができるため好ましい。Alternatively, a hole transport layer having a high p property doped with impurities can be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, and JP-A-2001-102175. Appl. Phys. 95, 5773 (2004), and the like.
In the present invention, it is preferable to use a hole transport layer having such a high p property because a device with lower power consumption can be manufactured.
本発明においては、このようなｐ性の高い正孔輸送層を用いることが、より低消費電力の素子を作製することができるため好ましい。Alternatively, a hole transport layer having a high p property doped with impurities can be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, and JP-A-2001-102175. Appl. Phys. 95, 5773 (2004), and the like.
In the present invention, it is preferable to use a hole transport layer having such a high p property because a device with lower power consumption can be manufactured.
《電子輸送層》
電子輸送層とは、電子を輸送する機能を有する材料からなり、広い意味で電子注入層、正孔阻止層も電子輸送層に含まれる。電子輸送層は単層または複数層設けることができる。《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.
電子輸送層とは、電子を輸送する機能を有する材料からなり、広い意味で電子注入層、正孔阻止層も電子輸送層に含まれる。電子輸送層は単層または複数層設けることができる。《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.
単層の電子輸送層および複数層とする場合、発光層に対して陰極側に隣接する電子輸送層に用いられる電子輸送材料（正孔阻止材料を兼ねる）としては、陰極より注入された電子を発光層に伝達する機能を有していればよく、その材料としては従来公知の化合物の中から任意のものを選択して用いることができ、たとえば、ニトロ置換フルオレン誘導体、ジフェニルキノン誘導体、チオピランジオキシド誘導体、カルボジイミド、フレオレニリデンメタン誘導体、アントラキノジメタンおよびアントロン誘導体、オキサジアゾール誘導体等が挙げられる。さらに、上記オキサジアゾール誘導体において、オキサジアゾール環の酸素原子を硫黄原子に置換したチアジアゾール誘導体、電子吸引基として知られているキノキサリン環を有するキノキサリン誘導体も、電子輸送材料として用いることができる。さらに、これらの材料を高分子鎖に導入した、またはこれらの材料を高分子の主鎖とした高分子材料を用いることもできる。In the case of a single-layer electron transport layer and a plurality of layers, as an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the cathode side with respect to the light emitting layer, electrons injected from the cathode are used. Any material can be used as long as it has a function of transmitting to the light-emitting layer, and any material can be selected from conventionally known compounds. For example, nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrans can be used. Dioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives and the like can be mentioned. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, or a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.
また、８－キノリノール誘導体の金属錯体、たとえば、トリス（８－キノリノール）アルミニウム（Ａｌｑ）、トリス（５，７－ジクロロ－８－キノリノール）アルミニウム、トリス（５，７－ジブロモ－８－キノリノール）アルミニウム、トリス（２－メチル－８－キノリノール）アルミニウム、トリス（５－メチル－８－キノリノール）アルミニウム、ビス（８－キノリノール）亜鉛（Ｚｎｑ）等、およびこれらの金属錯体の中心金属がＩｎ、Ｍｇ、Ｃｕ、Ｃａ、Ｓｎ、ＧａまたはＰｂに置き替わった金属錯体も、電子輸送材料として用いることができる。その他、メタルフリーもしくはメタルフタロシアニン、またはそれらの末端がアルキル基やスルホン酸基等で置換されているものも、電子輸送材料として好ましく用いることができる。また、発光層の材料として例示したジスチリルピラジン誘導体も、電子輸送材料として用いることができるし、正孔注入層、正孔輸送層と同様にｎ型－Ｓｉ、ｎ型－ＳｉＣ等の無機半導体も電子輸送材料として用いることができる。In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), and the like, and the central metals of these metal complexes are In, Mg, Metal complexes replaced with Cu, Ca, Sn, Ga or Pb can also be used as the electron transport material. In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. In addition, the distyrylpyrazine derivative exemplified as the material for the light emitting layer can also be used as an electron transport material, and an inorganic semiconductor such as n-type-Si, n-type-SiC, etc. as in the case of the hole injection layer and the hole transport layer. Can also be used as an electron transporting material.
電子輸送層は、上記電子輸送材料を、たとえば、真空蒸着法、スピンコート法、キャスト法、インクジェット法を含む印刷法、ＬＢ法等の公知の方法により、薄膜化することにより形成することができる。電子輸送層の膜厚については特に制限はないが、通常は５ｎｍ～５μｍ程度、好ましくは５ｎｍ～２００ｎｍである。電子輸送層は上記材料の１種または２種以上からなる一層構造であってもよい。The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. . The thickness of the electron transport layer is not particularly limited, but is usually about 5 nm to 5 μm, preferably 5 nm to 200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.
また、不純物をドープしたｎ性の高い電子輸送層を用いることもできる。その例としては、特開平４－２９７０７６号公報、同１０－２７０１７２号公報、特開２０００－１９６１４０号公報、同２００１－１０２１７５号公報、Ｊ．Ａｐｐｌ．Ｐｈｙｓ．，９５，５７７３（２００４）等に記載されたものが挙げられる。
本発明においては、このようなｎ性の高い電子輸送層を用いることがより低消費電力の素子を作製することができるため好ましい。Further, an electron transport layer having a high n property doped with impurities can also be used. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.
In the present invention, it is preferable to use an electron transport layer having such a high n property because an element with lower power consumption can be manufactured.
本発明においては、このようなｎ性の高い電子輸送層を用いることがより低消費電力の素子を作製することができるため好ましい。Further, an electron transport layer having a high n property doped with impurities can also be used. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.
In the present invention, it is preferable to use an electron transport layer having such a high n property because an element with lower power consumption can be manufactured.
《陽極》
有機ＥＬ素子における陽極としては、仕事関数の大きい（４ｅＶ以上）金属、合金、電気伝導性化合物およびこれらの混合物を電極物質とするものが好ましく用いられる。
このような電極物質の具体例としては、Ａｕ等の金属、ＣｕＩ、インジウムチンオキシド（ＩＴＯ）、ＳｎＯ２、ＺｎＯ等の導電性透明材料が挙げられる。また、ＩＤＩＸＯ（Ｉｎ２Ｏ３－ＺｎＯ）等非晶質で透明導電膜を作製可能な材料を用いてもよい。陽極は、これらの電極物質を蒸着やスパッタリング等の方法により薄膜を形成させ、フォトリソグラフィー法で所望の形状のパターンを形成してもよく、あるいはパターン精度をあまり必要としない場合は（１００μｍ以上程度）、上記電極物質の蒸着やスパッタリング時に所望の形状のマスクを介してパターンを形成してもよい。あるいは、有機導電性化合物のように塗布可能な物質を用いる場合には、印刷方式、コーティング方式等湿式成膜法を用いることもできる。"anode"
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound and a mixture thereof having a high work function (4 eV or more) is preferably used.
Specific examples of such electrode substances include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO2 , and ZnO. Alternatively, an amorphous material such as IDIXO (In2 O3 —ZnO) capable of forming a transparent conductive film may be used. For the anode, a thin film may be formed by depositing these electrode materials by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by photolithography, or when the pattern accuracy is not so high (about 100 μm or more) ), A pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film-forming methods, such as a printing system and a coating system, can also be used.
有機ＥＬ素子における陽極としては、仕事関数の大きい（４ｅＶ以上）金属、合金、電気伝導性化合物およびこれらの混合物を電極物質とするものが好ましく用いられる。
このような電極物質の具体例としては、Ａｕ等の金属、ＣｕＩ、インジウムチンオキシド（ＩＴＯ）、ＳｎＯ２、ＺｎＯ等の導電性透明材料が挙げられる。また、ＩＤＩＸＯ（Ｉｎ２Ｏ３－ＺｎＯ）等非晶質で透明導電膜を作製可能な材料を用いてもよい。陽極は、これらの電極物質を蒸着やスパッタリング等の方法により薄膜を形成させ、フォトリソグラフィー法で所望の形状のパターンを形成してもよく、あるいはパターン精度をあまり必要としない場合は（１００μｍ以上程度）、上記電極物質の蒸着やスパッタリング時に所望の形状のマスクを介してパターンを形成してもよい。あるいは、有機導電性化合物のように塗布可能な物質を用いる場合には、印刷方式、コーティング方式等湿式成膜法を用いることもできる。"anode"
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound and a mixture thereof having a high work function (4 eV or more) is preferably used.
Specific examples of such electrode substances include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO2 , and ZnO. Alternatively, an amorphous material such as IDIXO (In2 O3 —ZnO) capable of forming a transparent conductive film may be used. For the anode, a thin film may be formed by depositing these electrode materials by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by photolithography, or when the pattern accuracy is not so high (about 100 μm or more) ), A pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film-forming methods, such as a printing system and a coating system, can also be used.
この陽極より発光を取り出す場合には、透過率を１０％より大きくすることが望ましく、また陽極としてのシート抵抗は数百Ω／□以下が好ましい。さらに、膜厚は材料にもよるが、通常１０ｎｍ～１０００ｎｍ、好ましくは１０ｎｍ～２００ｎｍの範囲で選ばれる。When light emission is taken out from the anode, it is desirable that the transmittance is greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 nm to 1000 nm, preferably 10 nm to 200 nm.
《陰極》
一方、陰極としては、仕事関数の小さい（４ｅＶ以下）金属（電子注入性金属と称する）、合金、電気伝導性化合物およびこれらの混合物を電極物質とするものが用いられる。このような電極物質の具体例としては、ナトリウム、ナトリウム－カリウム合金、マグネシウム、リチウム、マグネシウム／銅混合物、マグネシウム／銀混合物、マグネシウム／アルミニウム混合物、マグネシウム／インジウム混合物、アルミニウム／酸化アルミニウム（Ａｌ２Ｏ３）混合物、インジウム、リチウム／アルミニウム混合物、希土類金属等が挙げられる。これらの中で、電子注入性および酸化等に対する耐久性の点から、電子注入性金属とこれより仕事関数の値が大きく安定な金属である第二金属との混合物、たとえば、マグネシウム／銀混合物、マグネシウム／アルミニウム混合物、マグネシウム／インジウム混合物、アルミニウム／酸化アルミニウム（Ａｌ２Ｏ３）混合物、リチウム／アルミニウム混合物、アルミニウム等が好適である。陰極は、これらの電極物質を蒸着やスパッタリング等の方法により薄膜を形成させることにより、作製することができる。"cathode"
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al2 O3 ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al2 O3 ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering.
一方、陰極としては、仕事関数の小さい（４ｅＶ以下）金属（電子注入性金属と称する）、合金、電気伝導性化合物およびこれらの混合物を電極物質とするものが用いられる。このような電極物質の具体例としては、ナトリウム、ナトリウム－カリウム合金、マグネシウム、リチウム、マグネシウム／銅混合物、マグネシウム／銀混合物、マグネシウム／アルミニウム混合物、マグネシウム／インジウム混合物、アルミニウム／酸化アルミニウム（Ａｌ２Ｏ３）混合物、インジウム、リチウム／アルミニウム混合物、希土類金属等が挙げられる。これらの中で、電子注入性および酸化等に対する耐久性の点から、電子注入性金属とこれより仕事関数の値が大きく安定な金属である第二金属との混合物、たとえば、マグネシウム／銀混合物、マグネシウム／アルミニウム混合物、マグネシウム／インジウム混合物、アルミニウム／酸化アルミニウム（Ａｌ２Ｏ３）混合物、リチウム／アルミニウム混合物、アルミニウム等が好適である。陰極は、これらの電極物質を蒸着やスパッタリング等の方法により薄膜を形成させることにより、作製することができる。"cathode"
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al2 O3 ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al2 O3 ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering.
また、陰極としてのシート抵抗は数百Ω／□以下が好ましく、膜厚は通常１０ｎｍ～５μｍ、好ましくは５０ｎｍ～２００ｎｍの範囲で選ばれる。なお、発光した光を透過させるため、有機ＥＬ素子の陽極または陰極のいずれか一方が透明または半透明であれば発光輝度が向上し好都合である。The sheet resistance as a cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 nm to 200 nm. In order to transmit the emitted light, if either the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.
また、陰極に上記金属を１ｎｍ～２０ｎｍの膜厚で作製した後に、陽極の説明で挙げた導電性透明材料をその上に作製することで、透明または半透明の陰極を作製することができ、これを応用することで陽極と陰極の両方が透過性を有する素子を作製することができる。In addition, a transparent or semi-transparent cathode can be produced by producing the conductive transparent material mentioned in the description of the anode on the cathode after producing the metal with a film thickness of 1 nm to 20 nm. By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.
《支持基板》
本発明の有機ＥＬ素子に用いることのできる支持基板（以下、基体、基板、基材、支持体等とも言う）としては、ガラス、プラスチック等の種類には特に限定はなく、また透明であっても不透明であってもよい。支持基板側から光を取り出す場合には、支持基板は透明であることが好ましい。好ましく用いられる透明な支持基板としては、ガラス、石英、透明樹脂フィルムを挙げることができる。特に好ましい支持基板は、有機ＥＬ素子にフレキシブル性を与えることが可能な樹脂フィルムである。《Support substrate》
As a support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention, there is no particular limitation on the type of glass, plastic, etc., and it is transparent. May be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of giving flexibility to the organic EL element.
本発明の有機ＥＬ素子に用いることのできる支持基板（以下、基体、基板、基材、支持体等とも言う）としては、ガラス、プラスチック等の種類には特に限定はなく、また透明であっても不透明であってもよい。支持基板側から光を取り出す場合には、支持基板は透明であることが好ましい。好ましく用いられる透明な支持基板としては、ガラス、石英、透明樹脂フィルムを挙げることができる。特に好ましい支持基板は、有機ＥＬ素子にフレキシブル性を与えることが可能な樹脂フィルムである。《Support substrate》
As a support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention, there is no particular limitation on the type of glass, plastic, etc., and it is transparent. May be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of giving flexibility to the organic EL element.
樹脂フィルムとしては、たとえば、ポリエチレンテレフタレート（ＰＥＴ）、ポリエチレンナフタレート（ＰＥＮ）等のポリエステル、ポリエチレン、ポリプロピレン、セロファン、セルロースジアセテート、セルローストリアセテート、セルロースアセテートブチレート、セルロースアセテートプロピオネート（ＣＡＰ）、セルロースアセテートフタレート（ＴＡＣ）、セルロースナイトレート等のセルロースエステル類またはそれらの誘導体、ポリ塩化ビニリデン、ポリビニルアルコール、ポリエチレンビニルアルコール、シンジオタクティックポリスチレン、ポリカーボネート、ノルボルネン樹脂、ポリメチルペンテン、ポリエーテルケトン、ポリイミド、ポリエーテルスルホン（ＰＥＳ）、ポリフェニレンスルフィド、ポリスルホン類、ポリエーテルイミド、ポリエーテルケトンイミド、ポリアミド、フッ素樹脂、ナイロン、ポリメチルメタクリレート、アクリルあるいはポリアリレート類、アートン（商品名ＪＳＲ社製）あるいはアペル（商品名三井化学社製）といったシクロオレフィン系樹脂等を挙げられる。
樹脂フィルムの表面には、無機物、有機物の被膜またはその両者のハイブリッド被膜が形成されていてもよく、水蒸気透過度が０．０１ｇ／（ｍ２・２４ｈ・ａｔｍ）以下のバリア性フィルムであることが好ましく、さらには、酸素透過度１×１０－３ｍｌ／（ｍ２・２４ｈ）以下および水蒸気透過度１×１０－５ｇ／（ｍ２・２４ｈ）以下の高バリア性フィルムであることが好ましい。Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfone , Polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylates, cyclone resins such as Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Etc.
The surface of the resin film may be formed with an inorganic film, an organic film, or a hybrid film of both, and the barrier film has a water vapor permeability of 0.01 g / (m2 · 24 h · atm) or less. Further, it is a high barrier film having an oxygen permeability of 1 × 10−3 ml / (m2 · 24 h) or less and a water vapor permeability of 1 × 10−5 g / (m2 · 24 h) or less. preferable.
樹脂フィルムの表面には、無機物、有機物の被膜またはその両者のハイブリッド被膜が形成されていてもよく、水蒸気透過度が０．０１ｇ／（ｍ２・２４ｈ・ａｔｍ）以下のバリア性フィルムであることが好ましく、さらには、酸素透過度１×１０－３ｍｌ／（ｍ２・２４ｈ）以下および水蒸気透過度１×１０－５ｇ／（ｍ２・２４ｈ）以下の高バリア性フィルムであることが好ましい。Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfone , Polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylates, cyclone resins such as Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Etc.
The surface of the resin film may be formed with an inorganic film, an organic film, or a hybrid film of both, and the barrier film has a water vapor permeability of 0.01 g / (m2 · 24 h · atm) or less. Further, it is a high barrier film having an oxygen permeability of 1 × 10−3 ml / (m2 · 24 h) or less and a water vapor permeability of 1 × 10−5 g / (m2 · 24 h) or less. preferable.
バリア膜を形成する材料としては、水分や酸素等素子の劣化をもたらすものの浸入を抑制する機能を有する材料であればよく、たとえば、酸化珪素、二酸化珪素、窒化珪素等を用いることができる。さらに、該膜の脆弱性を改良するために、これら無機層と有機材料からなる層の積層構造を持たせることがより好ましい。無機層と有機層の積層順については特に制限はないが、両者を交互に複数回積層させることが好ましい。
バリア膜の形成方法については特に限定はなく、たとえば、真空蒸着法、スパッタリング法、反応性スパッタリング法、分子線エピタキシー法、クラスタ－イオンビーム法、イオンプレーティング法、プラズマ重合法、大気圧プラズマ重合法、プラズマＣＶＤ法、レーザーＣＶＤ法、熱ＣＶＤ法、コーティング法等を用いることができるが、特開２００４－６８１４３号公報に記載されているような大気圧プラズマ重合法によるものが特に好ましい。As a material for forming the barrier film, any material may be used as long as it has a function of suppressing entry of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used. Furthermore, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and layers made of organic materials. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.
The method for forming the barrier film is not particularly limited. For example, the vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma weight A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, and the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.
バリア膜の形成方法については特に限定はなく、たとえば、真空蒸着法、スパッタリング法、反応性スパッタリング法、分子線エピタキシー法、クラスタ－イオンビーム法、イオンプレーティング法、プラズマ重合法、大気圧プラズマ重合法、プラズマＣＶＤ法、レーザーＣＶＤ法、熱ＣＶＤ法、コーティング法等を用いることができるが、特開２００４－６８１４３号公報に記載されているような大気圧プラズマ重合法によるものが特に好ましい。As a material for forming the barrier film, any material may be used as long as it has a function of suppressing entry of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used. Furthermore, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and layers made of organic materials. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.
The method for forming the barrier film is not particularly limited. For example, the vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma weight A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, and the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.
不透明な支持基板としては、たとえば、アルミ、ステンレス等の金属板、フィルムや不透明樹脂基板、セラミック製の基板等が挙げられる。
本発明の有機ＥＬ素子の発光の室温における外部取り出し効率は、１％以上であることが好ましく、より好ましくは５％以上である。ここに、外部取り出し量子効率（％）＝有機ＥＬ素子外部に発光した光子数／有機ＥＬ素子に流した電子数×１００である。Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, ceramic substrates, and the like.
The external extraction efficiency at room temperature of light emission of the organic EL device of the present invention is preferably 1% or more, more preferably 5% or more. Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.
本発明の有機ＥＬ素子の発光の室温における外部取り出し効率は、１％以上であることが好ましく、より好ましくは５％以上である。ここに、外部取り出し量子効率（％）＝有機ＥＬ素子外部に発光した光子数／有機ＥＬ素子に流した電子数×１００である。Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, ceramic substrates, and the like.
The external extraction efficiency at room temperature of light emission of the organic EL device of the present invention is preferably 1% or more, more preferably 5% or more. Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.
また、カラーフィルター等の色相改良フィルター等を併用してもよいし、有機ＥＬ素子からの発光色を蛍光体を用いて多色へ変換する色変換フィルターを併用してもよい。色変換フィルターを用いる場合においては、有機ＥＬ素子の発光のλｍａｘは４８０ｎｍ以下が好ましい。Further, a hue improving filter such as a color filter may be used in combination, or a color conversion filter for converting the emission color from the organic EL element into multiple colors using a phosphor may be used in combination. In the case of using a color conversion filter, the λmax of light emission of the organic EL element is preferably 480 nm or less.
《封止》
本発明に用いられる封止手段としては、たとえば、封止部材と電極、支持基板とを接着剤で接着する方法を挙げることができる。
封止部材としては、有機ＥＬ素子の表示領域を覆うように配置されていればよく、凹板状でも平板状でもよい。また、透明性、電気絶縁性は特に問わない。
具体的には、ガラス板、ポリマー板・フィルム、金属板・フィルム等が挙げられる。ガラス板としては、特にソーダ石灰ガラス、バリウム・ストロンチウム含有ガラス、鉛ガラス、アルミノケイ酸ガラス、ホウケイ酸ガラス、バリウムホウケイ酸ガラス、石英等を挙げることができる。また、ポリマー板としては、ポリカーボネート、アクリル、ポリエチレンテレフタレート、ポリエーテルサルファイド、ポリサルフォン等を挙げることができる。金属板としては、ステンレス、鉄、銅、アルミニウム、マグネシウム、ニッケル、亜鉛、クロム、チタン、モリブテン、シリコン、ゲルマニウムおよびタンタルからなる群から選ばれる一種以上の金属または合金からなるものが挙げられる。<Sealing>
As a sealing means used for this invention, the method of adhere | attaching a sealing member, an electrode, and a support substrate with an adhesive agent can be mentioned, for example.
The sealing member may be disposed so as to cover the display area of the organic EL element, and may be a concave plate shape or a flat plate shape. Further, transparency and electrical insulation are not particularly limited.
Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.
本発明に用いられる封止手段としては、たとえば、封止部材と電極、支持基板とを接着剤で接着する方法を挙げることができる。
封止部材としては、有機ＥＬ素子の表示領域を覆うように配置されていればよく、凹板状でも平板状でもよい。また、透明性、電気絶縁性は特に問わない。
具体的には、ガラス板、ポリマー板・フィルム、金属板・フィルム等が挙げられる。ガラス板としては、特にソーダ石灰ガラス、バリウム・ストロンチウム含有ガラス、鉛ガラス、アルミノケイ酸ガラス、ホウケイ酸ガラス、バリウムホウケイ酸ガラス、石英等を挙げることができる。また、ポリマー板としては、ポリカーボネート、アクリル、ポリエチレンテレフタレート、ポリエーテルサルファイド、ポリサルフォン等を挙げることができる。金属板としては、ステンレス、鉄、銅、アルミニウム、マグネシウム、ニッケル、亜鉛、クロム、チタン、モリブテン、シリコン、ゲルマニウムおよびタンタルからなる群から選ばれる一種以上の金属または合金からなるものが挙げられる。<Sealing>
As a sealing means used for this invention, the method of adhere | attaching a sealing member, an electrode, and a support substrate with an adhesive agent can be mentioned, for example.
The sealing member may be disposed so as to cover the display area of the organic EL element, and may be a concave plate shape or a flat plate shape. Further, transparency and electrical insulation are not particularly limited.
Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.
本発明においては、素子を薄膜化できるということからポリマーフィルム、金属フィルムを好ましく使用することができる。さらには、ポリマーフィルムは、ＪＩＳ Ｋ ７１２６－１９８７に準拠した方法で測定された酸素透過度が１×１０－３ｍｌ／（ｍ２・２４ｈ）以下、ＪＩＳ Ｋ ７１２９－１９９２に準拠した方法で測定された、水蒸気透過度（２５±０．５℃、相対湿度（９０±２）％ＲＨが、１×１０－３ｇ／（ｍ２・２４ｈ）以下のものであることが好ましい。
封止部材を凹状に加工するのは、サンドブラスト加工、化学エッチング加工等が使われる。In the present invention, a polymer film and a metal film can be preferably used because the element can be thinned. Furthermore, the polymer film has an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 × 10−3 ml / (m2 · 24 h) or less, and measured by a method according to JIS K 7129-1992. The water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH is preferably 1 × 10−3 g / (m2 · 24 h) or less.
For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.
封止部材を凹状に加工するのは、サンドブラスト加工、化学エッチング加工等が使われる。In the present invention, a polymer film and a metal film can be preferably used because the element can be thinned. Furthermore, the polymer film has an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 × 10−3 ml / (m2 · 24 h) or less, and measured by a method according to JIS K 7129-1992. The water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH is preferably 1 × 10−3 g / (m2 · 24 h) or less.
For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.
接着剤として、具体的には、アクリル酸系オリゴマー、メタクリル酸系オリゴマーの反応性ビニル基を有する光硬化および熱硬化型接着剤、２－シアノアクリル酸エステル等の湿気硬化型等の接着剤を挙げることができる。また、エポキシ系等の熱および化学硬化型（二液混合）を挙げることができる。また、ホットメルト型のポリアミド、ポリエステル、ポリオレフィンを挙げることができる。また、カチオン硬化タイプの紫外線硬化型エポキシ樹脂接着剤を挙げることができる。
なお、有機ＥＬ素子が熱処理により劣化する場合があるので、室温から８０℃までに接着硬化できるものが好ましい。また、接着剤中に乾燥剤を分散させておいてもよい。封止部分への接着剤の塗布は市販のディスペンサーを使ってもよいし、スクリーン印刷のように印刷してもよい。Specific examples of adhesives include photo-curing and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. Can be mentioned. Moreover, heat | fever and chemical curing types (two liquid mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.
In addition, since an organic EL element may deteriorate by heat processing, what can be adhesive-hardened from room temperature to 80 degreeC is preferable. Further, a desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.
なお、有機ＥＬ素子が熱処理により劣化する場合があるので、室温から８０℃までに接着硬化できるものが好ましい。また、接着剤中に乾燥剤を分散させておいてもよい。封止部分への接着剤の塗布は市販のディスペンサーを使ってもよいし、スクリーン印刷のように印刷してもよい。Specific examples of adhesives include photo-curing and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. Can be mentioned. Moreover, heat | fever and chemical curing types (two liquid mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.
In addition, since an organic EL element may deteriorate by heat processing, what can be adhesive-hardened from room temperature to 80 degreeC is preferable. Further, a desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.
また、有機層を挟み支持基板と対向する側の電極の外側に該電極と有機層を被覆し、支持基板と接する形で無機物、有機物の層を形成し封止膜とすることも好適にできる。この場合、該膜を形成する材料としては、水分や酸素等素子の劣化をもたらすものの浸入を抑制する機能を有する材料であればよく、たとえば、酸化珪素、二酸化珪素、窒化珪素等を用いることができる。さらに、該膜の脆弱性を改良するために、これら無機層と有機材料からなる層の積層構造を持たせることが好ましい。これらの膜の形成方法については、特に限定はなく、たとえば真空蒸着法、スパッタリング法、反応性スパッタリング法、分子線エピタキシー法、クラスタ－イオンビーム法、イオンプレーティング法、プラズマ重合法、大気圧プラズマ重合法、プラズマＣＶＤ法、レーザーＣＶＤ法、熱ＣＶＤ法、コーティング法等を用いることができる。In addition, it is also preferable that the electrode and the organic layer are coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. . In this case, the material for forming the film may be any material that has a function of suppressing infiltration of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can. Furthermore, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. The method for forming these films is not particularly limited. For example, vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma A polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.
封止部材と有機ＥＬ素子の表示領域との間隙には、気相および液相では、窒素、アルゴン等の不活性気体やフッ化炭化水素、シリコンオイルのような不活性液体を注入することが好ましい。また、真空とすることも可能である。また、内部に吸湿性化合物を封入することもできる。
吸湿性化合物としては、たとえば、金属酸化物（たとえば、酸化ナトリウム、酸化カリウム、酸化カルシウム、酸化バリウム、酸化マグネシウム、酸化アルミニウム等）、硫酸塩（たとえば、硫酸ナトリウム、硫酸カルシウム、硫酸マグネシウム、硫酸コバルト等）、金属ハロゲン化物（たとえば、塩化カルシウム、塩化マグネシウム、フッ化セシウム、フッ化タンタル、臭化セリウム、臭化マグネシウム、沃化バリウム、沃化マグネシウム等）、過塩素酸類（たとえば、過塩素酸バリウム、過塩素酸マグネシウム等）等が挙げられ、硫酸塩、金属ハロゲン化物および過塩素酸類においては無水塩が好適に用いられる。In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase. preferable. A vacuum can also be used. Moreover, a hygroscopic compound can also be enclosed inside.
Examples of the hygroscopic compound include metal oxides (eg, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide), sulfates (eg, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (for example, calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide, etc.), perchloric acids (for example, perchloric acid) Barium, magnesium perchlorate, etc.), and anhydrous salts are preferably used in sulfates, metal halides and perchloric acids.
吸湿性化合物としては、たとえば、金属酸化物（たとえば、酸化ナトリウム、酸化カリウム、酸化カルシウム、酸化バリウム、酸化マグネシウム、酸化アルミニウム等）、硫酸塩（たとえば、硫酸ナトリウム、硫酸カルシウム、硫酸マグネシウム、硫酸コバルト等）、金属ハロゲン化物（たとえば、塩化カルシウム、塩化マグネシウム、フッ化セシウム、フッ化タンタル、臭化セリウム、臭化マグネシウム、沃化バリウム、沃化マグネシウム等）、過塩素酸類（たとえば、過塩素酸バリウム、過塩素酸マグネシウム等）等が挙げられ、硫酸塩、金属ハロゲン化物および過塩素酸類においては無水塩が好適に用いられる。In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase. preferable. A vacuum can also be used. Moreover, a hygroscopic compound can also be enclosed inside.
Examples of the hygroscopic compound include metal oxides (eg, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide), sulfates (eg, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (for example, calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide, etc.), perchloric acids (for example, perchloric acid) Barium, magnesium perchlorate, etc.), and anhydrous salts are preferably used in sulfates, metal halides and perchloric acids.
《保護膜、保護板》
有機層を挟み支持基板と対向する側の封止膜、あるいは封止用フィルムの外側に、素子の機械的強度を高めるために保護膜、あるいは保護板を設けてもよい。特に封止が上記封止膜により行われている場合には、その機械的強度は必ずしも高くないため、このような保護膜、保護板を設けることが好ましい。
これに使用することができる材料としては、封止に用いたのと同様なガラス板、ポリマー板・フィルム、金属板・フィルム等を用いることができるが、軽量かつ薄膜化ということからポリマーフィルムを用いることが好ましい。《Protective film, protective plate》
In order to increase the mechanical strength of the element, a protective film or a protective plate may be provided on the outer side of the sealing film or the sealing film on the side facing the support substrate with the organic layer interposed therebetween. In particular, when the sealing is performed by the sealing film, the mechanical strength is not necessarily high. Therefore, it is preferable to provide such a protective film and a protective plate.
As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, etc. used for sealing can be used. It is preferable to use it.
有機層を挟み支持基板と対向する側の封止膜、あるいは封止用フィルムの外側に、素子の機械的強度を高めるために保護膜、あるいは保護板を設けてもよい。特に封止が上記封止膜により行われている場合には、その機械的強度は必ずしも高くないため、このような保護膜、保護板を設けることが好ましい。
これに使用することができる材料としては、封止に用いたのと同様なガラス板、ポリマー板・フィルム、金属板・フィルム等を用いることができるが、軽量かつ薄膜化ということからポリマーフィルムを用いることが好ましい。《Protective film, protective plate》
In order to increase the mechanical strength of the element, a protective film or a protective plate may be provided on the outer side of the sealing film or the sealing film on the side facing the support substrate with the organic layer interposed therebetween. In particular, when the sealing is performed by the sealing film, the mechanical strength is not necessarily high. Therefore, it is preferable to provide such a protective film and a protective plate.
As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, etc. used for sealing can be used. It is preferable to use it.
《光取り出し》
有機ＥＬ素子は、空気よりも屈折率の高い（屈折率が１．７～２．１程度）層の内部で発光し、発光層で発生した光のうち１５％から２０％程度の光しか取り出せないことが一般的に言われている。これは、臨界角以上の角度θで界面（透明基板と空気との界面）に入射する光は、全反射を起こし素子外部に取り出すことができないことや、透明電極ないし発光層と透明基板との間で光が全反射を起こし、光が透明電極ないし発光層を導波し、結果として光が素子側面方向に逃げるためである。《Light extraction》
The organic EL element emits light inside a layer having a refractive index higher than that of air (refractive index is about 1.7 to 2.1), and can extract only about 15% to 20% of the light generated in the light emitting layer. It is generally said that there is no. This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be taken out of the device, or between the transparent electrode or light emitting layer and the transparent substrate. This is because the light undergoes total reflection between the light and the light, and the light is guided through the transparent electrode or the light emitting layer.
有機ＥＬ素子は、空気よりも屈折率の高い（屈折率が１．７～２．１程度）層の内部で発光し、発光層で発生した光のうち１５％から２０％程度の光しか取り出せないことが一般的に言われている。これは、臨界角以上の角度θで界面（透明基板と空気との界面）に入射する光は、全反射を起こし素子外部に取り出すことができないことや、透明電極ないし発光層と透明基板との間で光が全反射を起こし、光が透明電極ないし発光層を導波し、結果として光が素子側面方向に逃げるためである。《Light extraction》
The organic EL element emits light inside a layer having a refractive index higher than that of air (refractive index is about 1.7 to 2.1), and can extract only about 15% to 20% of the light generated in the light emitting layer. It is generally said that there is no. This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be taken out of the device, or between the transparent electrode or light emitting layer and the transparent substrate. This is because the light undergoes total reflection between the light and the light, and the light is guided through the transparent electrode or the light emitting layer.
この光の取り出しの効率を向上させる手法としては、たとえば、透明基板表面に凹凸を形成し、透明基板と空気界面での全反射を防ぐ方法（米国特許第４，７７４，４３５号明細書）、基板に集光性を持たせることにより効率を向上させる方法（特開昭６３－３１４７９５号公報）、素子の側面等に反射面を形成する方法（特開平１－２２０３９４号公報）、基板と発光体の間に中間の屈折率を持つ平坦層を導入し、反射防止膜を形成する方法（特開昭６２－１７２６９１号公報）、基板と発光体の間に基板よりも低屈折率を持つ平坦層を導入する方法（特開２００１－２０２８２７号公報）、基板、透明電極層や発光層のいずれかの層間（含む、基板と外界間）に回折格子を形成する方法（特開平１１－２８３７５１号公報）等がある。
本発明においては、これらの方法を本発明の有機ＥＬ素子と組み合わせて用いることができるが、基板と発光体の間に基板よりも低屈折率を持つ平坦層を導入する方法、あるいは基板、透明電極層や発光層のいずれかの層間（含む、基板と外界間）に回折格子を形成する方法を好適に用いることができる。
本発明においては、これらの手段を組み合わせることにより、さらに高輝度あるいは耐久性に優れた素子を得ることができる。As a method for improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the interface between the transparent substrate and the air (US Pat. No. 4,774,435), A method for improving efficiency by giving light condensing property to a substrate (Japanese Patent Laid-Open No. 63-314795), a method of forming a reflective surface on the side surface of an element (Japanese Patent Laid-Open No. 1-220394), and light emission from the substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the bodies (Japanese Patent Laid-Open No. 62-172691), a flat having a lower refractive index between the substrate and the light emitter than the substrate A method of introducing a layer (Japanese Patent Laid-Open No. 2001-202827), a method of forming a diffraction grating between any one of a substrate, a transparent electrode layer and a light emitting layer (including between the substrate and the outside) (Japanese Patent Laid-Open No. 11-283951) Gazette).
In the present invention, these methods can be used in combination with the organic EL device of the present invention. However, a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, transparent A method of forming a diffraction grating between any layers of the electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.
In the present invention, by combining these means, it is possible to obtain an element having higher luminance or durability.
本発明においては、これらの方法を本発明の有機ＥＬ素子と組み合わせて用いることができるが、基板と発光体の間に基板よりも低屈折率を持つ平坦層を導入する方法、あるいは基板、透明電極層や発光層のいずれかの層間（含む、基板と外界間）に回折格子を形成する方法を好適に用いることができる。
本発明においては、これらの手段を組み合わせることにより、さらに高輝度あるいは耐久性に優れた素子を得ることができる。As a method for improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the interface between the transparent substrate and the air (US Pat. No. 4,774,435), A method for improving efficiency by giving light condensing property to a substrate (Japanese Patent Laid-Open No. 63-314795), a method of forming a reflective surface on the side surface of an element (Japanese Patent Laid-Open No. 1-220394), and light emission from the substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the bodies (Japanese Patent Laid-Open No. 62-172691), a flat having a lower refractive index between the substrate and the light emitter than the substrate A method of introducing a layer (Japanese Patent Laid-Open No. 2001-202827), a method of forming a diffraction grating between any one of a substrate, a transparent electrode layer and a light emitting layer (including between the substrate and the outside) (Japanese Patent Laid-Open No. 11-283951) Gazette).
In the present invention, these methods can be used in combination with the organic EL device of the present invention. However, a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, transparent A method of forming a diffraction grating between any layers of the electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.
In the present invention, by combining these means, it is possible to obtain an element having higher luminance or durability.
透明電極と透明基板の間に低屈折率の媒質を光の波長よりも長い厚みで形成すると、透明電極から出てきた光は、媒質の屈折率が低いほど外部への取り出し効率が高くなる。
低屈折率層としては、たとえば、エアロゲル、多孔質シリカ、フッ化マグネシウム、フッ素系ポリマー等が挙げられる。透明基板の屈折率は一般に１．５～１．７程度であるので、低屈折率層は屈折率がおよそ１．５以下であることが好ましい。さらには、１．３５以下であることがより好ましい。
また、低屈折率媒質の厚みは媒質中の波長の２倍以上となることが望ましい。これは低屈折率媒質の厚みが、光の波長程度になってエバネッセントで染み出した電磁波が基板内に入り込む膜厚になると、低屈折率層の効果が薄れるからである。When a medium having a low refractive index is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the light extracted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower.
Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Furthermore, it is more preferable that it is 1.35 or less.
The thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low refractive index layer is diminished when the thickness of the low refractive index medium is about the wavelength of light and the electromagnetic wave that has exuded by evanescent enters the substrate.
低屈折率層としては、たとえば、エアロゲル、多孔質シリカ、フッ化マグネシウム、フッ素系ポリマー等が挙げられる。透明基板の屈折率は一般に１．５～１．７程度であるので、低屈折率層は屈折率がおよそ１．５以下であることが好ましい。さらには、１．３５以下であることがより好ましい。
また、低屈折率媒質の厚みは媒質中の波長の２倍以上となることが望ましい。これは低屈折率媒質の厚みが、光の波長程度になってエバネッセントで染み出した電磁波が基板内に入り込む膜厚になると、低屈折率層の効果が薄れるからである。When a medium having a low refractive index is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the light extracted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower.
Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Furthermore, it is more preferable that it is 1.35 or less.
The thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low refractive index layer is diminished when the thickness of the low refractive index medium is about the wavelength of light and the electromagnetic wave that has exuded by evanescent enters the substrate.
全反射を起こす界面もしくはいずれかの媒質中に回折格子を導入する方法は、光取り出し効率の向上効果が高いという特徴がある。この方法は、回折格子が１次の回折や２次の回折といった所謂ブラッグ回折により、光の向きを屈折とは異なる特定の向きに変えることができる性質を利用して、発光層から発生した光のうち層間での全反射等により外に出ることができない光を、いずれかの層間もしくは媒質中（透明基板内や透明電極内）に回折格子を導入することで光を回折させ、光を外に取り出そうとするものである。
導入する回折格子は、二次元的な周期屈折率を持っていることが望ましい。これは発光層で発光する光はあらゆる方向にランダムに発生するので、ある方向にのみ周期的な屈折率分布を持っている一般的な１次元回折格子では、特定の方向に進む光しか回折されず、光の取り出し効率がさほど上がらない。しかしながら、屈折率分布を二次元的な分布にすることにより、あらゆる方向に進む光が回折され、光の取り出し効率が上がる。
回折格子を導入する位置としては前述の通り、いずれかの層間もしくは媒質中（透明基板内や透明電極内）でもよいが、光が発生する場所である有機発光層の近傍が望ましい。
このとき、回折格子の周期は媒質中の光の波長の約１／２～３倍程度が好ましい。
回折格子の配列は正方形のラチス状、三角形のラチス状、ハニカムラチス状等、２次元的に配列が繰り返されることが好ましい。The method of introducing a diffraction grating into an interface or any medium that causes total reflection is characterized by a high effect of improving light extraction efficiency. This method uses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction such as first-order diffraction and second-order diffraction. The light that cannot be emitted due to total reflection between layers, etc. is diffracted by introducing a diffraction grating into any layer or medium (in the transparent substrate or transparent electrode), and the light is I want to take it out.
The introduced diffraction grating desirably has a two-dimensional periodic refractive index. This is because light emitted from the light emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. Therefore, the light extraction efficiency does not increase so much. However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted, and light extraction efficiency is increased.
As described above, the position where the diffraction grating is introduced may be in any of the layers or in the medium (in the transparent substrate or in the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated.
At this time, the period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of light in the medium.
The arrangement of the diffraction grating is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.
導入する回折格子は、二次元的な周期屈折率を持っていることが望ましい。これは発光層で発光する光はあらゆる方向にランダムに発生するので、ある方向にのみ周期的な屈折率分布を持っている一般的な１次元回折格子では、特定の方向に進む光しか回折されず、光の取り出し効率がさほど上がらない。しかしながら、屈折率分布を二次元的な分布にすることにより、あらゆる方向に進む光が回折され、光の取り出し効率が上がる。
回折格子を導入する位置としては前述の通り、いずれかの層間もしくは媒質中（透明基板内や透明電極内）でもよいが、光が発生する場所である有機発光層の近傍が望ましい。
このとき、回折格子の周期は媒質中の光の波長の約１／２～３倍程度が好ましい。
回折格子の配列は正方形のラチス状、三角形のラチス状、ハニカムラチス状等、２次元的に配列が繰り返されることが好ましい。The method of introducing a diffraction grating into an interface or any medium that causes total reflection is characterized by a high effect of improving light extraction efficiency. This method uses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction such as first-order diffraction and second-order diffraction. The light that cannot be emitted due to total reflection between layers, etc. is diffracted by introducing a diffraction grating into any layer or medium (in the transparent substrate or transparent electrode), and the light is I want to take it out.
The introduced diffraction grating desirably has a two-dimensional periodic refractive index. This is because light emitted from the light emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. Therefore, the light extraction efficiency does not increase so much. However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted, and light extraction efficiency is increased.
As described above, the position where the diffraction grating is introduced may be in any of the layers or in the medium (in the transparent substrate or in the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated.
At this time, the period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of light in the medium.
The arrangement of the diffraction grating is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.
《集光シート》
本発明の有機ＥＬ素子は、基板の光取り出し側に、たとえば、マイクロレンズアレイ状の構造を設けるように加工したり、あるいは所謂集光シートと組み合わせることにより、特定方向、たとえば、素子発光面に対し正面方向に集光することにより、特定方向上の輝度を高めることができる。
マイクロレンズアレイの例としては、基板の光取り出し側に一辺が３０μｍでその頂角が９０度となるような四角錐を２次元に配列する。一辺は１０μｍ～１００μｍが好ましい。これより小さくなると回折の効果が発生して色付く、大きすぎると厚みが厚くなり好ましくない。
集光シートとしては、たとえば、液晶表示装置のＬＥＤバックライトで実用化されているものを用いることが可能である。このようなシートとして、たとえば、住友スリーエム社製輝度上昇フィルム（ＢＥＦ）等を用いることができる。プリズムシートの形状としては、たとえば、基材に頂角９０度、ピッチ５０μｍの△状のストライプが形成されたものであってもよいし、頂角が丸みを帯びた形状、ピッチをランダムに変化させた形状、その他の形状であってもよい。
また、発光素子からの光放射角を制御するために、光拡散板・フィルムを集光シートと併用してもよい。たとえば、（株）きもと製拡散フィルム（ライトアップ）等を用いることができる。<Condenser sheet>
The organic EL device of the present invention can be processed on the light extraction side of the substrate, for example, by providing a microlens array-like structure, or combined with a so-called condensing sheet, for example, in a specific direction, for example, the device light emitting surface On the other hand, the brightness | luminance in a specific direction can be raised by condensing in a front direction.
As an example of the microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are two-dimensionally arranged on the light extraction side of the substrate. One side is preferably 10 μm to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and if too large, thickness will become thick and is not preferable.
As the condensing sheet, for example, a sheet that is put into practical use in an LED backlight of a liquid crystal display device can be used. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used. As the shape of the prism sheet, for example, the base material may be formed with a △ -shaped stripe having a vertex angle of 90 degrees and a pitch of 50 μm, or the vertex angle is rounded and the pitch is changed randomly. Other shapes may be used.
Moreover, in order to control the light emission angle from a light emitting element, you may use together a light diffusing plate and a film with a condensing sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.
本発明の有機ＥＬ素子は、基板の光取り出し側に、たとえば、マイクロレンズアレイ状の構造を設けるように加工したり、あるいは所謂集光シートと組み合わせることにより、特定方向、たとえば、素子発光面に対し正面方向に集光することにより、特定方向上の輝度を高めることができる。
マイクロレンズアレイの例としては、基板の光取り出し側に一辺が３０μｍでその頂角が９０度となるような四角錐を２次元に配列する。一辺は１０μｍ～１００μｍが好ましい。これより小さくなると回折の効果が発生して色付く、大きすぎると厚みが厚くなり好ましくない。
集光シートとしては、たとえば、液晶表示装置のＬＥＤバックライトで実用化されているものを用いることが可能である。このようなシートとして、たとえば、住友スリーエム社製輝度上昇フィルム（ＢＥＦ）等を用いることができる。プリズムシートの形状としては、たとえば、基材に頂角９０度、ピッチ５０μｍの△状のストライプが形成されたものであってもよいし、頂角が丸みを帯びた形状、ピッチをランダムに変化させた形状、その他の形状であってもよい。
また、発光素子からの光放射角を制御するために、光拡散板・フィルムを集光シートと併用してもよい。たとえば、（株）きもと製拡散フィルム（ライトアップ）等を用いることができる。<Condenser sheet>
The organic EL device of the present invention can be processed on the light extraction side of the substrate, for example, by providing a microlens array-like structure, or combined with a so-called condensing sheet, for example, in a specific direction, for example, the device light emitting surface On the other hand, the brightness | luminance in a specific direction can be raised by condensing in a front direction.
As an example of the microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are two-dimensionally arranged on the light extraction side of the substrate. One side is preferably 10 μm to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and if too large, thickness will become thick and is not preferable.
As the condensing sheet, for example, a sheet that is put into practical use in an LED backlight of a liquid crystal display device can be used. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used. As the shape of the prism sheet, for example, the base material may be formed with a △ -shaped stripe having a vertex angle of 90 degrees and a pitch of 50 μm, or the vertex angle is rounded and the pitch is changed randomly. Other shapes may be used.
Moreover, in order to control the light emission angle from a light emitting element, you may use together a light diffusing plate and a film with a condensing sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.
《有機ＥＬ素子の作製方法》
有機化合物薄膜の薄膜化の方法としては、蒸着法またはウェットプロセス（スピンコート法、キャスト法、インクジェット法、スプレー塗布法、ブレード塗布法、エアーナイフ塗布法、ワイヤーバー塗布法、グラビア塗布法、フレキソ塗布法、リバース塗布法、リバースロール塗布法、エクストルージョン塗布法等）が挙げられる。また、層毎に異なる製膜法を適用してもよい。<< Method for producing organic EL element >>
Organic compound thin films can be made by vapor deposition or wet processes (spin coating, casting, ink jet, spray coating, blade coating, air knife coating, wire bar coating, gravure coating, flexographic coating, etc. Coating method, reverse coating method, reverse roll coating method, extrusion coating method, etc.). Different film forming methods may be applied for each layer.
有機化合物薄膜の薄膜化の方法としては、蒸着法またはウェットプロセス（スピンコート法、キャスト法、インクジェット法、スプレー塗布法、ブレード塗布法、エアーナイフ塗布法、ワイヤーバー塗布法、グラビア塗布法、フレキソ塗布法、リバース塗布法、リバースロール塗布法、エクストルージョン塗布法等）が挙げられる。また、層毎に異なる製膜法を適用してもよい。<< Method for producing organic EL element >>
Organic compound thin films can be made by vapor deposition or wet processes (spin coating, casting, ink jet, spray coating, blade coating, air knife coating, wire bar coating, gravure coating, flexographic coating, etc. Coating method, reverse coating method, reverse roll coating method, extrusion coating method, etc.). Different film forming methods may be applied for each layer.
製膜に蒸着法を採用する場合、その蒸着条件は使用する化合物の種類等により異なるが、一般にボート加熱温度５０～４５０℃、真空度１０－６～１０－２Ｐａ、蒸着速度０．０１～５０ｎｍ／秒、基板温度－５０～３００℃、膜厚０．１ｎｍ～５μｍ、好ましくは５～２００ｎｍの範囲で適宜選ぶことが望ましい。蒸着法の場合は、一回の真空引きで一貫して正孔注入層から陰極まで作製するのが好ましいが、途中で取り出して異なる製膜法を施しても構わない。その際、作業を乾燥不活性ガス雰囲気下で行う等の配慮が必要となる。また作製順序を逆にして、陰極、電子注入層、電子輸送層、発光層、正孔輸送層、正孔注入層、陽極の順に作製することも可能である。When a vapor deposition method is employed for film formation, the vapor deposition conditions vary depending on the type of compound used, but generally a boat heating temperature of 50 to 450 ° C., a degree of vacuum of 10−6 to 10−2 Pa, and a vapor deposition rate of 0.01 to It is desirable to select appropriately within a range of 50 nm / second, a substrate temperature of −50 to 300 ° C., and a film thickness of 0.1 nm to 5 μm, preferably 5 to 200 nm. In the case of the vapor deposition method, it is preferable to consistently produce from the hole injection layer to the cathode by one evacuation, but it may be taken out halfway and subjected to different film forming methods. At that time, it is necessary to consider that the work is performed in a dry inert gas atmosphere. In addition, it is also possible to reverse the production order and produce the cathode, the electron injection layer, the electron transport layer, the light emitting layer, the hole transport layer, the hole injection layer, and the anode in this order.
また、ウェットプロセスを用いる場合は、不活性ガス雰囲気下、かつ、クリーン環境で塗布することが好ましい。具体的には、ＪＩＳ Ｂ ９９２０に準拠し測定した清浄度がクラス１００以下で、露点温度が－７０℃以下、酸素濃度１ｐｐｍ以下、かつ、１０℃～４５℃の大気圧条件下の環境で行うことが好ましい。Also, when using a wet process, it is preferable to apply in a clean environment under an inert gas atmosphere. Specifically, cleanliness measured in accordance with JIS B 9920 is class 100 or lower, dew point temperature is −70 ° C. or lower, oxygen concentration is 1 ppm or lower, and atmospheric pressure conditions are 10 ° C. to 45 ° C. It is preferable.
これらの有機層を形成後、その上に陰極用物質からなる薄膜を、１μｍ以下、好ましくは５０～２００ｎｍの範囲の膜厚になるように、たとえば、蒸着やスパッタリング等の方法により形成させ、陰極を設けることにより所望の有機ＥＬ素子が得られる。
また、電極を塗布する場合は、融点の低い金属、合金、電気伝導性化合物およびこれらの混合物を融解し塗布してもよいし、金属の分散物等を塗布してもよい。After forming these organic layers, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably in the range of 50 to 200 nm. By providing the desired organic EL element can be obtained.
In addition, when applying an electrode, a metal, an alloy, an electrically conductive compound and a mixture thereof having a low melting point may be melted and applied, or a metal dispersion or the like may be applied.
また、電極を塗布する場合は、融点の低い金属、合金、電気伝導性化合物およびこれらの混合物を融解し塗布してもよいし、金属の分散物等を塗布してもよい。After forming these organic layers, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably in the range of 50 to 200 nm. By providing the desired organic EL element can be obtained.
In addition, when applying an electrode, a metal, an alloy, an electrically conductive compound and a mixture thereof having a low melting point may be melted and applied, or a metal dispersion or the like may be applied.
《用途》
本発明の有機ＥＬ素子は、表示デバイス、ディスプレイ、各種発光光源として用いることができる。発光光源として、たとえば、照明装置（家庭用照明、車内照明）、時計や液晶用バックライト、看板広告、信号機、光記憶媒体の光源、電子写真複写機の光源、光通信処理機の光源、光センサーの光源等が挙げられ、これに限定するものではないが、特に液晶表示装置のバックライト、照明用光源としての用途に有効に用いることができる。
本発明の有機ＥＬ素子においては、必要に応じ成膜時にメタルマスクやインクジェットプリンティング法等でパターニングを施してもよい。パターニングする場合は、電極のみをパターニングしてもよいし、電極と発光層をパターニングしてもよいし、素子全層をパターニングしてもよく、素子の作製においては、従来公知の方法を用いることができる。<Application>
The organic EL element of the present invention can be used as a display device, a display, and various light emission sources. For example, lighting devices (home lighting, interior lighting), clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light Examples include, but are not limited to, a light source of a sensor. In particular, the light source can be effectively used for a backlight of a liquid crystal display device and a light source for illumination.
In the organic EL element of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like as needed during film formation. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned. In the fabrication of the element, a conventionally known method is used. Can do.
本発明の有機ＥＬ素子は、表示デバイス、ディスプレイ、各種発光光源として用いることができる。発光光源として、たとえば、照明装置（家庭用照明、車内照明）、時計や液晶用バックライト、看板広告、信号機、光記憶媒体の光源、電子写真複写機の光源、光通信処理機の光源、光センサーの光源等が挙げられ、これに限定するものではないが、特に液晶表示装置のバックライト、照明用光源としての用途に有効に用いることができる。
本発明の有機ＥＬ素子においては、必要に応じ成膜時にメタルマスクやインクジェットプリンティング法等でパターニングを施してもよい。パターニングする場合は、電極のみをパターニングしてもよいし、電極と発光層をパターニングしてもよいし、素子全層をパターニングしてもよく、素子の作製においては、従来公知の方法を用いることができる。<Application>
The organic EL element of the present invention can be used as a display device, a display, and various light emission sources. For example, lighting devices (home lighting, interior lighting), clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light Examples include, but are not limited to, a light source of a sensor. In particular, the light source can be effectively used for a backlight of a liquid crystal display device and a light source for illumination.
In the organic EL element of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like as needed during film formation. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned. In the fabrication of the element, a conventionally known method is used. Can do.
本発明の有機ＥＬ素子や本発明にかかる化合物の発光する色は、「新編色彩科学ハンドブック」（日本色彩学会編、東京大学出版会、１９８５）の１０８頁の図４．１６において、分光放射輝度計ＣＳ－１０００（コニカミノルタセンシング社製）で測定した結果をＣＩＥ色度座標に当てはめたときの色で決定される。
また、本発明の有機ＥＬ素子が白色素子の場合には、白色とは、２度視野角正面輝度を上記方法により測定した際に、１０００Ｃｄ／ｍ２でのＣＩＥ１９３１表色系における色度がＸ＝０．３３±０．０７、Ｙ＝０．３３±０．１の領域内にあることを言う。The light emission color of the organic EL device of the present invention and the compound according to the present invention is shown in FIG. 4.16 on page 108 of “New Color Science Handbook” (edited by the Japan Color Society, University of Tokyo Press, 1985). It is determined by the color when the result measured with a total CS-1000 (manufactured by Konica Minolta Sensing) is applied to the CIE chromaticity coordinates.
Further, when the organic EL device of the present invention is a white device, white means that the chromaticity in the CIE1931 color system at 1000 Cd / m2 is X when the 2 ° viewing angle front luminance is measured by the above method. = 0.33 ± 0.07 and Y = 0.33 ± 0.1.
また、本発明の有機ＥＬ素子が白色素子の場合には、白色とは、２度視野角正面輝度を上記方法により測定した際に、１０００Ｃｄ／ｍ２でのＣＩＥ１９３１表色系における色度がＸ＝０．３３±０．０７、Ｙ＝０．３３±０．１の領域内にあることを言う。The light emission color of the organic EL device of the present invention and the compound according to the present invention is shown in FIG. 4.16 on page 108 of “New Color Science Handbook” (edited by the Japan Color Society, University of Tokyo Press, 1985). It is determined by the color when the result measured with a total CS-1000 (manufactured by Konica Minolta Sensing) is applied to the CIE chromaticity coordinates.
Further, when the organic EL device of the present invention is a white device, white means that the chromaticity in the CIE1931 color system at 1000 Cd / m2 is X when the 2 ° viewing angle front luminance is measured by the above method. = 0.33 ± 0.07 and Y = 0.33 ± 0.1.
以下、実施例を挙げて本発明を具体的に説明するが、本発明はこれらに限定されるものではない。Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
《有機ＥＬ素子の作製》
（１）有機ＥＬ素子（サンプル）１の作製
陽極として、１００ｍｍ×１００ｍｍ×１．１ｍｍのガラス基板上にＩＴＯ（インジウムチンオキシド）を厚さ１００ｎｍで成膜した基板（ＮＨテクノグラス社製ＮＡ４５）にパターニングを行った後、このＩＴＯ透明電極を設けた透明支持基板をイソプロピルアルコールで超音波洗浄し、乾燥窒素ガスで乾燥し、ＵＶオゾン洗浄を５分間行った。
この透明支持基板を市販の真空蒸着装置の基板ホルダーに固定し、一方モリブデン製抵抗加熱ボートに構造を以下に示すＨＴ－３０を２００ｍｇ入れ、別のモリブデン抵抗加熱ボートに構造を以下に示すＨＴ－２を２００ｍｇ入れ、別のモリブデン製抵抗加熱ボートにａ－１を２００ｍｇ入れ、別のモリブデン製抵抗加熱ボートに構造を以下に示す比較化合物を２００ｍｇ入れ、別のモリブデン製抵抗加熱ボートにドＩｒ－６を２００ｍｇ入れ、別のモリブデン製抵抗加熱ボートに構造を以下に示すＥＴ－７を２００ｍｇ入れ、真空蒸着装置に取り付けた。
次いで、真空槽を４×１０－４Ｐａまで減圧した後、ＨＴ－３０の入った加熱ボートに通電して加熱し、蒸着速度０．１ｎｍ／秒で透明支持基板に蒸着し、膜厚１０ｎｍの正孔注入層を設けた。
さらに、ＨＴ－２の入った加熱ボートに通電して加熱し、蒸着速度０．１ｎｍ／秒で正孔注入層上に蒸着し、膜厚３０ｎｍの正孔輸送層を設けた。
さらに、ａ－１，比較化合物，Ｉｒ－１，Ｉｒ－６の入った加熱ボートに通電して加熱し、それぞれ蒸着速度０．１ｎｍ／秒、０．０２ｎｍ／秒、０．０００１ｎｍ／秒、０．０００２ｎｍ／秒で正孔輸送層上に共蒸着し、膜厚４０ｎｍの発光層を設けた。
さらに、ＥＴ－７の入った加熱ボートに通電して加熱し、蒸着速度０．１ｎｍ／秒で発光層上に蒸着し、膜厚３０ｎｍの発光層の陰極側隣接層となる電子輸送層（ＥＴＬ）を設けた。
引き続き、電子注入層として、フッ化リチウムを膜厚０．５ｎｍで蒸着し、さらにアルミニウムを膜厚１１０ｎｍで蒸着して陰極を形成し、有機ＥＬ素子１を作製した。<< Production of organic EL element >>
(1) Preparation of organic EL element (sample) 1 As an anode, a substrate (NA Technoglass NA45) formed by depositing ITO (indium tin oxide) with a thickness of 100 nm on a 100 mm × 100 mm × 1.1 mm glass substrate After patterning, the transparent support substrate provided with the ITO transparent electrode was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.
This transparent support substrate is fixed to a substrate holder of a commercially available vacuum deposition apparatus, while 200 mg of HT-30 having the following structure is placed in a molybdenum resistance heating boat, and HT- 200 mg of a-1 is put in another molybdenum resistance heating boat, 200 mg of a comparative compound having the structure shown below is put in another resistance heating boat made of molybdenum, and Ir- 200 mg of ET-7 having the structure shown below was put in another resistance heating boat made of molybdenum and attached to a vacuum deposition apparatus.
Next, the pressure in the vacuum chamber was reduced to 4 × 10−4 Pa and then heated by energizing a heating boat containing HT-30, and deposited on the transparent support substrate at a deposition rate of 0.1 nm / second. A hole injection layer was provided.
Further, the heating boat containing HT-2 was energized and heated, and deposited on the hole injection layer at a deposition rate of 0.1 nm / second to provide a hole transport layer having a thickness of 30 nm.
Further, the heating boat containing a-1, comparative compound, Ir-1, and Ir-6 was energized and heated, and the deposition rates were 0.1 nm / second, 0.02 nm / second, 0.0001 nm / second, 0, respectively. Co-deposited on the hole transport layer at a rate of .0002 nm / second to provide a 40 nm thick light emitting layer.
Further, an electron transport layer (ETL) which is heated by energizing a heating boat containing ET-7, deposited on the light emitting layer at a deposition rate of 0.1 nm / second, and serving as a cathode side adjacent layer of the light emitting layer having a thickness of 30 nm. ).
Subsequently, as an electron injection layer, lithium fluoride was vapor-deposited with a film thickness of 0.5 nm, and aluminum was vapor-deposited with a film thickness of 110 nm to form a cathode, whereby theorganic EL element 1 was produced.
（１）有機ＥＬ素子（サンプル）１の作製
陽極として、１００ｍｍ×１００ｍｍ×１．１ｍｍのガラス基板上にＩＴＯ（インジウムチンオキシド）を厚さ１００ｎｍで成膜した基板（ＮＨテクノグラス社製ＮＡ４５）にパターニングを行った後、このＩＴＯ透明電極を設けた透明支持基板をイソプロピルアルコールで超音波洗浄し、乾燥窒素ガスで乾燥し、ＵＶオゾン洗浄を５分間行った。
この透明支持基板を市販の真空蒸着装置の基板ホルダーに固定し、一方モリブデン製抵抗加熱ボートに構造を以下に示すＨＴ－３０を２００ｍｇ入れ、別のモリブデン抵抗加熱ボートに構造を以下に示すＨＴ－２を２００ｍｇ入れ、別のモリブデン製抵抗加熱ボートにａ－１を２００ｍｇ入れ、別のモリブデン製抵抗加熱ボートに構造を以下に示す比較化合物を２００ｍｇ入れ、別のモリブデン製抵抗加熱ボートにドＩｒ－６を２００ｍｇ入れ、別のモリブデン製抵抗加熱ボートに構造を以下に示すＥＴ－７を２００ｍｇ入れ、真空蒸着装置に取り付けた。
次いで、真空槽を４×１０－４Ｐａまで減圧した後、ＨＴ－３０の入った加熱ボートに通電して加熱し、蒸着速度０．１ｎｍ／秒で透明支持基板に蒸着し、膜厚１０ｎｍの正孔注入層を設けた。
さらに、ＨＴ－２の入った加熱ボートに通電して加熱し、蒸着速度０．１ｎｍ／秒で正孔注入層上に蒸着し、膜厚３０ｎｍの正孔輸送層を設けた。
さらに、ａ－１，比較化合物，Ｉｒ－１，Ｉｒ－６の入った加熱ボートに通電して加熱し、それぞれ蒸着速度０．１ｎｍ／秒、０．０２ｎｍ／秒、０．０００１ｎｍ／秒、０．０００２ｎｍ／秒で正孔輸送層上に共蒸着し、膜厚４０ｎｍの発光層を設けた。
さらに、ＥＴ－７の入った加熱ボートに通電して加熱し、蒸着速度０．１ｎｍ／秒で発光層上に蒸着し、膜厚３０ｎｍの発光層の陰極側隣接層となる電子輸送層（ＥＴＬ）を設けた。
引き続き、電子注入層として、フッ化リチウムを膜厚０．５ｎｍで蒸着し、さらにアルミニウムを膜厚１１０ｎｍで蒸着して陰極を形成し、有機ＥＬ素子１を作製した。<< Production of organic EL element >>
(1) Preparation of organic EL element (sample) 1 As an anode, a substrate (NA Technoglass NA45) formed by depositing ITO (indium tin oxide) with a thickness of 100 nm on a 100 mm × 100 mm × 1.1 mm glass substrate After patterning, the transparent support substrate provided with the ITO transparent electrode was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.
This transparent support substrate is fixed to a substrate holder of a commercially available vacuum deposition apparatus, while 200 mg of HT-30 having the following structure is placed in a molybdenum resistance heating boat, and HT- 200 mg of a-1 is put in another molybdenum resistance heating boat, 200 mg of a comparative compound having the structure shown below is put in another resistance heating boat made of molybdenum, and Ir- 200 mg of ET-7 having the structure shown below was put in another resistance heating boat made of molybdenum and attached to a vacuum deposition apparatus.
Next, the pressure in the vacuum chamber was reduced to 4 × 10−4 Pa and then heated by energizing a heating boat containing HT-30, and deposited on the transparent support substrate at a deposition rate of 0.1 nm / second. A hole injection layer was provided.
Further, the heating boat containing HT-2 was energized and heated, and deposited on the hole injection layer at a deposition rate of 0.1 nm / second to provide a hole transport layer having a thickness of 30 nm.
Further, the heating boat containing a-1, comparative compound, Ir-1, and Ir-6 was energized and heated, and the deposition rates were 0.1 nm / second, 0.02 nm / second, 0.0001 nm / second, 0, respectively. Co-deposited on the hole transport layer at a rate of .0002 nm / second to provide a 40 nm thick light emitting layer.
Further, an electron transport layer (ETL) which is heated by energizing a heating boat containing ET-7, deposited on the light emitting layer at a deposition rate of 0.1 nm / second, and serving as a cathode side adjacent layer of the light emitting layer having a thickness of 30 nm. ).
Subsequently, as an electron injection layer, lithium fluoride was vapor-deposited with a film thickness of 0.5 nm, and aluminum was vapor-deposited with a film thickness of 110 nm to form a cathode, whereby the
その後、ガラスカバーを準備して、その側縁部に対し、シール剤としてエポキシ系光硬化型接着剤（東亞合成社製ラクストラックＬＣ０６２９Ｂ）を塗布し、この部位を、有機ＥＬ素子１の非発光面（陰極側）をガラスカバーで被覆するように、有機ＥＬ素子１のガラス基板に密着させた。
その後、有機ＥＬ素子１のガラス基板側からＵＶ光を照射して接着剤を硬化させ、有機ＥＬ素子１をガラスカバーで封止した。当該封止後の有機ＥＬ素子１を「サンプル１」とした。Thereafter, a glass cover is prepared, and an epoxy-based photocurable adhesive (Luxtrac LC0629B manufactured by Toagosei Co., Ltd.) is applied as a sealant to the side edge of the glass cover. The surface (cathode side) was adhered to the glass substrate of theorganic EL element 1 so as to be covered with a glass cover.
Then, UV light was irradiated from the glass substrate side of theorganic EL element 1 to cure the adhesive, and theorganic EL element 1 was sealed with a glass cover. Theorganic EL element 1 after the sealing was designated as “Sample 1”.
その後、有機ＥＬ素子１のガラス基板側からＵＶ光を照射して接着剤を硬化させ、有機ＥＬ素子１をガラスカバーで封止した。当該封止後の有機ＥＬ素子１を「サンプル１」とした。Thereafter, a glass cover is prepared, and an epoxy-based photocurable adhesive (Luxtrac LC0629B manufactured by Toagosei Co., Ltd.) is applied as a sealant to the side edge of the glass cover. The surface (cathode side) was adhered to the glass substrate of the
Then, UV light was irradiated from the glass substrate side of the
（２）有機ＥＬ素子（サンプル）２～４の作製
有機ＥＬ素子１の作製において、ホスト化合物を表２に記載の化合物に変えた以外は同様にして有機ＥＬ素子２～４を作製し、それぞれサンプル２～４とした。(2) Preparation of organic EL elements (samples) 2 to 4 Organic EL elements 2 to 4 were prepared in the same manner except that the host compound was changed to the compounds shown in Table 2 in preparation of theorganic EL element 1. Samples 2 to 4 were used.
有機ＥＬ素子１の作製において、ホスト化合物を表２に記載の化合物に変えた以外は同様にして有機ＥＬ素子２～４を作製し、それぞれサンプル２～４とした。(2) Preparation of organic EL elements (samples) 2 to 4 Organic EL elements 2 to 4 were prepared in the same manner except that the host compound was changed to the compounds shown in Table 2 in preparation of the
（３）有機ＥＬ素子（サンプル）５の作製
有機ＥＬ素子１の作製において、発光層の構成を下記のように変えた以外は同様にして有機ＥＬ素子５を作製し、サンプル５とした。(3) Preparation of organic EL element (sample) 5 Organic EL element 5 was prepared in the same manner as Sample 5 except that the structure of the light-emitting layer was changed as described below.
有機ＥＬ素子１の作製において、発光層の構成を下記のように変えた以外は同様にして有機ＥＬ素子５を作製し、サンプル５とした。(3) Preparation of organic EL element (sample) 5 Organic EL element 5 was prepared in the same manner as Sample 5 except that the structure of the light-emitting layer was changed as described below.
正孔輸送層上に、ａ－１１，Ｉｒ－１，Ｉｒ－６の入った加熱ボートに通電して加熱し、それぞれ蒸着速度０．１ｎｍ／秒、０．０００１ｎｍ／秒、０．０００２ｎｍ／秒で正孔輸送層上に共蒸着し、膜厚２０ｎｍの第一発光層を設けた。
次いで、第一発光層上に、ａ－９，ＤＰ－１の入った加熱ボートに通電して加熱し、それぞれ蒸着速度０．１ｎｍ／秒、０．０２ｎｍ／秒で第一発光層上に共蒸着し、膜厚２０ｎｍの第二発光層を設けた。
なお、上記第一発光層および第二発光層の各膜厚は、発光層全体としての総膜厚が４０ｎｍとなるように蒸着した。On the hole transport layer, a heating boat containing a-11, Ir-1, and Ir-6 was energized and heated, and the deposition rates were 0.1 nm / second, 0.0001 nm / second, and 0.0002 nm / second, respectively. And co-evaporated on the hole transport layer to provide a first light-emitting layer having a thickness of 20 nm.
Next, a heating boat containing a-9 and DP-1 is energized and heated on the first light emitting layer, and the first light emitting layer is coated on the first light emitting layer at a deposition rate of 0.1 nm / second and 0.02 nm / second, respectively. The second light emitting layer having a thickness of 20 nm was provided by vapor deposition.
In addition, each film thickness of the said 1st light emitting layer and the 2nd light emitting layer was vapor-deposited so that the total film thickness as the whole light emitting layer might be 40 nm.
次いで、第一発光層上に、ａ－９，ＤＰ－１の入った加熱ボートに通電して加熱し、それぞれ蒸着速度０．１ｎｍ／秒、０．０２ｎｍ／秒で第一発光層上に共蒸着し、膜厚２０ｎｍの第二発光層を設けた。
なお、上記第一発光層および第二発光層の各膜厚は、発光層全体としての総膜厚が４０ｎｍとなるように蒸着した。On the hole transport layer, a heating boat containing a-11, Ir-1, and Ir-6 was energized and heated, and the deposition rates were 0.1 nm / second, 0.0001 nm / second, and 0.0002 nm / second, respectively. And co-evaporated on the hole transport layer to provide a first light-emitting layer having a thickness of 20 nm.
Next, a heating boat containing a-9 and DP-1 is energized and heated on the first light emitting layer, and the first light emitting layer is coated on the first light emitting layer at a deposition rate of 0.1 nm / second and 0.02 nm / second, respectively. The second light emitting layer having a thickness of 20 nm was provided by vapor deposition.
In addition, each film thickness of the said 1st light emitting layer and the 2nd light emitting layer was vapor-deposited so that the total film thickness as the whole light emitting layer might be 40 nm.
（４）有機ＥＬ素子（サンプル）６の作製
有機ＥＬ素子１の作製において、発光層の構成を下記のように変えた以外は同様にして有機ＥＬ素子６を作製し、サンプル６とした。(4) Preparation of Organic EL Element (Sample) 6 Organic EL element 6 was prepared in the same manner as Sample 6 except that the structure of the light emitting layer was changed as follows in the preparation oforganic EL element 1.
有機ＥＬ素子１の作製において、発光層の構成を下記のように変えた以外は同様にして有機ＥＬ素子６を作製し、サンプル６とした。(4) Preparation of Organic EL Element (Sample) 6 Organic EL element 6 was prepared in the same manner as Sample 6 except that the structure of the light emitting layer was changed as follows in the preparation of
正孔輸送層上に、ａ－９，ＤＰ－１の入った加熱ボートに通電して加熱し、それぞれ蒸着速度０．１ｎｍ／秒、０．０２ｎｍ／秒で正孔輸送層上に共蒸着し、膜厚２０ｎｍの第一発光層を設けた。
次いで、第一発光層上に、ａ－１１，Ｉｒ－１，Ｉｒ－６の入った加熱ボートに通電して加熱し、それぞれ蒸着速度０．１ｎｍ／秒、０．０００１ｎｍ／秒、０．０００２ｎｍ／秒で第一発光層上に共蒸着し、膜厚２０ｎｍの第二発光層を設けた。
なお、上記第一発光層および第二発光層の各膜厚は、発光層全体としての総膜厚が４０ｎｍとなるように蒸着した。On the hole transport layer, a heating boat containing a-9 and DP-1 is energized and heated, and co-deposited on the hole transport layer at a deposition rate of 0.1 nm / second and 0.02 nm / second, respectively. A first light emitting layer having a thickness of 20 nm was provided.
Next, the first light emitting layer was heated by energizing a heating boat containing a-11, Ir-1, and Ir-6, and the deposition rates were 0.1 nm / second, 0.0001 nm / second, and 0.0002 nm, respectively. / Second was co-evaporated on the first light emitting layer, and a second light emitting layer having a thickness of 20 nm was provided.
In addition, each film thickness of the said 1st light emitting layer and the 2nd light emitting layer was vapor-deposited so that the total film thickness as the whole light emitting layer might be 40 nm.
次いで、第一発光層上に、ａ－１１，Ｉｒ－１，Ｉｒ－６の入った加熱ボートに通電して加熱し、それぞれ蒸着速度０．１ｎｍ／秒、０．０００１ｎｍ／秒、０．０００２ｎｍ／秒で第一発光層上に共蒸着し、膜厚２０ｎｍの第二発光層を設けた。
なお、上記第一発光層および第二発光層の各膜厚は、発光層全体としての総膜厚が４０ｎｍとなるように蒸着した。On the hole transport layer, a heating boat containing a-9 and DP-1 is energized and heated, and co-deposited on the hole transport layer at a deposition rate of 0.1 nm / second and 0.02 nm / second, respectively. A first light emitting layer having a thickness of 20 nm was provided.
Next, the first light emitting layer was heated by energizing a heating boat containing a-11, Ir-1, and Ir-6, and the deposition rates were 0.1 nm / second, 0.0001 nm / second, and 0.0002 nm, respectively. / Second was co-evaporated on the first light emitting layer, and a second light emitting layer having a thickness of 20 nm was provided.
In addition, each film thickness of the said 1st light emitting layer and the 2nd light emitting layer was vapor-deposited so that the total film thickness as the whole light emitting layer might be 40 nm.
（５）有機ＥＬ素子（サンプル）７の作製
有機ＥＬ素子１の作製において、発光層の構成を下記のように変えた以外は同様にして有機ＥＬ素子７を作製し、サンプル７とした。(5) Preparation of Organic EL Element (Sample) 7 In the preparation of theorganic EL element 1, the organic EL element 7 was prepared in the same manner except that the configuration of the light emitting layer was changed as described below.
有機ＥＬ素子１の作製において、発光層の構成を下記のように変えた以外は同様にして有機ＥＬ素子７を作製し、サンプル７とした。(5) Preparation of Organic EL Element (Sample) 7 In the preparation of the
正孔輸送層上に、ａ－１１，Ｉｒ－１，Ｉｒ－６の入った加熱ボートに通電して加熱し、それぞれ蒸着速度０．１ｎｍ／秒、０．０００１ｎｍ／秒、０．０００２ｎｍ／秒で正孔輸送層上に共蒸着し、膜厚１３．３ｎｍの第一発光層を設けた。
次いで、第一発光層上に、ａ－９，ＤＰ－１の入った加熱ボートに通電して加熱し、それぞれ蒸着速度０．１ｎｍ／秒、０．０２ｎｍ／秒で第一発光層上に共蒸着し、膜厚１３．４ｎｍの第二発光層を設けた。
さらに、第二発光層上に、ａ－９，ＤＰ－１，Ｉｒ－６の入った加熱ボートに通電して加熱し、それぞれ蒸着速度０．１ｎｍ／秒、０．０２ｎｍ／秒、０．０００２ｎｍ／秒で第二発光層上に共蒸着し、膜厚１３．３ｎｍの第三発光層を設けた。
なお、上記第一発光層、第二発光層および第三発光層の各膜厚は、発光層全体としての総膜厚が４０ｎｍとなるように蒸着した。On the hole transport layer, a heating boat containing a-11, Ir-1, and Ir-6 was energized and heated, and the deposition rates were 0.1 nm / second, 0.0001 nm / second, and 0.0002 nm / second, respectively. And co-evaporated on the hole transport layer to provide a first light emitting layer having a thickness of 13.3 nm.
Next, a heating boat containing a-9 and DP-1 is energized and heated on the first light emitting layer, and the first light emitting layer is coated on the first light emitting layer at a deposition rate of 0.1 nm / second and 0.02 nm / second, respectively. It vapor-deposited and provided the 2nd light emitting layer with a film thickness of 13.4 nm.
Further, the second light emitting layer was heated by energizing a heating boat containing a-9, DP-1, and Ir-6, and the deposition rates were 0.1 nm / second, 0.02 nm / second, and 0.0002 nm, respectively. / Second was co-evaporated on the second light emitting layer, and a third light emitting layer having a thickness of 13.3 nm was provided.
In addition, each film thickness of the said 1st light emitting layer, the 2nd light emitting layer, and the 3rd light emitting layer was vapor-deposited so that the total film thickness as a whole light emitting layer might be 40 nm.
次いで、第一発光層上に、ａ－９，ＤＰ－１の入った加熱ボートに通電して加熱し、それぞれ蒸着速度０．１ｎｍ／秒、０．０２ｎｍ／秒で第一発光層上に共蒸着し、膜厚１３．４ｎｍの第二発光層を設けた。
さらに、第二発光層上に、ａ－９，ＤＰ－１，Ｉｒ－６の入った加熱ボートに通電して加熱し、それぞれ蒸着速度０．１ｎｍ／秒、０．０２ｎｍ／秒、０．０００２ｎｍ／秒で第二発光層上に共蒸着し、膜厚１３．３ｎｍの第三発光層を設けた。
なお、上記第一発光層、第二発光層および第三発光層の各膜厚は、発光層全体としての総膜厚が４０ｎｍとなるように蒸着した。On the hole transport layer, a heating boat containing a-11, Ir-1, and Ir-6 was energized and heated, and the deposition rates were 0.1 nm / second, 0.0001 nm / second, and 0.0002 nm / second, respectively. And co-evaporated on the hole transport layer to provide a first light emitting layer having a thickness of 13.3 nm.
Next, a heating boat containing a-9 and DP-1 is energized and heated on the first light emitting layer, and the first light emitting layer is coated on the first light emitting layer at a deposition rate of 0.1 nm / second and 0.02 nm / second, respectively. It vapor-deposited and provided the 2nd light emitting layer with a film thickness of 13.4 nm.
Further, the second light emitting layer was heated by energizing a heating boat containing a-9, DP-1, and Ir-6, and the deposition rates were 0.1 nm / second, 0.02 nm / second, and 0.0002 nm, respectively. / Second was co-evaporated on the second light emitting layer, and a third light emitting layer having a thickness of 13.3 nm was provided.
In addition, each film thickness of the said 1st light emitting layer, the 2nd light emitting layer, and the 3rd light emitting layer was vapor-deposited so that the total film thickness as a whole light emitting layer might be 40 nm.
（６）有機ＥＬ素子（サンプル）８～１０の作製
有機ＥＬ素子５の作製において、ホスト化合物、青色ドーパント、発光層の陰極側隣接層である電子輸送層の構成材料を表２に記載の化合物に変えた以外は同様にして有機ＥＬ素子８～１０を作製し、それぞれサンプル８～１０とした。(6) Preparation of organic EL elements (samples) 8 to 10 In the preparation of organic EL element 5, the compounds shown in Table 2 are used as constituent materials for the host compound, the blue dopant, and the electron transport layer adjacent to the cathode side of the light emitting layer. Organic EL elements 8 to 10 were produced in the same manner except that the samples were changed to Samples 8 to 10.
有機ＥＬ素子５の作製において、ホスト化合物、青色ドーパント、発光層の陰極側隣接層である電子輸送層の構成材料を表２に記載の化合物に変えた以外は同様にして有機ＥＬ素子８～１０を作製し、それぞれサンプル８～１０とした。(6) Preparation of organic EL elements (samples) 8 to 10 In the preparation of organic EL element 5, the compounds shown in Table 2 are used as constituent materials for the host compound, the blue dopant, and the electron transport layer adjacent to the cathode side of the light emitting layer. Organic EL elements 8 to 10 were produced in the same manner except that the samples were changed to Samples 8 to 10.
なお、表２中、ホスト化合物は、青色リン光ドーパントと同一の発光層で使用したもののみを示している。In Table 2, only the host compounds used in the same light emitting layer as the blue phosphorescent dopant are shown.
《有機ＥＬ素子（サンプル）１～１０の評価》
（１）駆動電圧および発光効率
分光放射輝度計ＣＳ－１０００（コニカミノルタセンシング社製）を用いて、各有機ＥＬ素子の正面輝度および輝度角度依存性を測定し、正面輝度１０００ｃｄ／ｍ２における駆動電圧および発光効率を求めた。
評価結果を表２に示す。駆動電圧および発光効率は、サンプル１の電力効率を１００と設定する相対値で表した。
なお、表２中、発光層が２層または３層からなる場合、表２中左側が陽極に近い側となっている。また、表２中、ＬＵＭＯ（Ｃ）とは、発光層の陰極側隣接層である電子輸送層の構成材料のＬＵＭＯ準位を表す。<< Evaluation of organic EL elements (samples) 1-10 >>
(1) Driving voltage and luminous efficiency Using a spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing Co., Ltd.), the front luminance and luminance angle dependency of each organic EL element are measured, and driving at a front luminance of 1000 cd / m2 is performed. The voltage and luminous efficiency were determined.
The evaluation results are shown in Table 2. The drive voltage and the light emission efficiency were expressed as relative values that set the power efficiency ofSample 1 to 100.
In Table 2, when the light emitting layer is composed of two or three layers, the left side in Table 2 is the side closer to the anode. In Table 2, LUMO (C) represents the LUMO level of the constituent material of the electron transport layer which is the cathode side adjacent layer of the light emitting layer.
（１）駆動電圧および発光効率
分光放射輝度計ＣＳ－１０００（コニカミノルタセンシング社製）を用いて、各有機ＥＬ素子の正面輝度および輝度角度依存性を測定し、正面輝度１０００ｃｄ／ｍ２における駆動電圧および発光効率を求めた。
評価結果を表２に示す。駆動電圧および発光効率は、サンプル１の電力効率を１００と設定する相対値で表した。
なお、表２中、発光層が２層または３層からなる場合、表２中左側が陽極に近い側となっている。また、表２中、ＬＵＭＯ（Ｃ）とは、発光層の陰極側隣接層である電子輸送層の構成材料のＬＵＭＯ準位を表す。<< Evaluation of organic EL elements (samples) 1-10 >>
(1) Driving voltage and luminous efficiency Using a spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing Co., Ltd.), the front luminance and luminance angle dependency of each organic EL element are measured, and driving at a front luminance of 1000 cd / m2 is performed. The voltage and luminous efficiency were determined.
The evaluation results are shown in Table 2. The drive voltage and the light emission efficiency were expressed as relative values that set the power efficiency of
In Table 2, when the light emitting layer is composed of two or three layers, the left side in Table 2 is the side closer to the anode. In Table 2, LUMO (C) represents the LUMO level of the constituent material of the electron transport layer which is the cathode side adjacent layer of the light emitting layer.
（２）発光領域（再結合領域）の測定
各サンプルを、正面の発光輝度が初期輝度からその約半分になるまで電気駆動させ（この状態をΔＥＬ＝０．５と目標設定する。）、その駆動前後でフォトルミネッセンスのスペクトルを測定して発光極大の強度を算出して減衰率（ΔＰＬ）を算出した。
「ΔＥＬ」は駆動前後のエレクトロルミネッセンス（ＥＬ）の強度減衰率を示し、「ΔＰＬ」は駆動前後のフォトルミネッセンス（ＰＬ）の強度減衰率を示す。
具体的に、ΔＥＬおよびΔＰＬの各値は下記の式で表される。(2) Measurement of light emission region (recombination region) Each sample is electrically driven until the front light emission luminance is about half that of the initial luminance (this state is set as ΔEL = 0.5). The photoluminescence spectrum was measured before and after driving, the intensity of the emission maximum was calculated, and the attenuation rate (ΔPL) was calculated.
“ΔEL” indicates the intensity decay rate of the electroluminescence (EL) before and after driving, and “ΔPL” indicates the intensity decay rate of the photoluminescence (PL) before and after driving.
Specifically, each value of ΔEL and ΔPL is expressed by the following formula.
各サンプルを、正面の発光輝度が初期輝度からその約半分になるまで電気駆動させ（この状態をΔＥＬ＝０．５と目標設定する。）、その駆動前後でフォトルミネッセンスのスペクトルを測定して発光極大の強度を算出して減衰率（ΔＰＬ）を算出した。
「ΔＥＬ」は駆動前後のエレクトロルミネッセンス（ＥＬ）の強度減衰率を示し、「ΔＰＬ」は駆動前後のフォトルミネッセンス（ＰＬ）の強度減衰率を示す。
具体的に、ΔＥＬおよびΔＰＬの各値は下記の式で表される。(2) Measurement of light emission region (recombination region) Each sample is electrically driven until the front light emission luminance is about half that of the initial luminance (this state is set as ΔEL = 0.5). The photoluminescence spectrum was measured before and after driving, the intensity of the emission maximum was calculated, and the attenuation rate (ΔPL) was calculated.
“ΔEL” indicates the intensity decay rate of the electroluminescence (EL) before and after driving, and “ΔPL” indicates the intensity decay rate of the photoluminescence (PL) before and after driving.
Specifically, each value of ΔEL and ΔPL is expressed by the following formula.
ΔＥＬ＝１－［ＥＬ（駆動後）／ＥＬ（駆動前）］
ΔＰＬ＝１－［ＰＬ（駆動後）／ＰＬ（駆動前）］ΔEL = 1− [EL (after driving) / EL (before driving)]
ΔPL = 1− [PL (after driving) / PL (before driving)]
ΔＰＬ＝１－［ＰＬ（駆動後）／ＰＬ（駆動前）］ΔEL = 1− [EL (after driving) / EL (before driving)]
ΔPL = 1− [PL (after driving) / PL (before driving)]
ＰＬのスペクトル測定にはＵＳＢ２０００（Ｏｃｅａｎ Ｏｐｔｉｃｓ製）を用い、当該スペクトル測定は室温（２３℃）、励起波長３６５ｎｍの条件でおこなった。駆動後のスペクトル測定は、ＥＬの初期輝度が約半分になるまで駆動させた後、その時点から２時間以内におこなった。
その後、ΔＰＬとΔＥＬとの各値の比（ΔＰＬ／ΔＥＬ）を算出した。
算出結果を表２に示す。
なお、発光領域は、サンプル１の発光領域を１００と設定する相対値で表した。USB spectrum (manufactured by Ocean Optics) was used for PL spectrum measurement, and the spectrum measurement was performed under conditions of room temperature (23 ° C.) and excitation wavelength of 365 nm. The spectrum measurement after the drive was performed within 2 hours from that time after the EL was driven until the initial luminance became about half.
Thereafter, the ratio of each value between ΔPL and ΔEL (ΔPL / ΔEL) was calculated.
Table 2 shows the calculation results.
In addition, the light emission area | region was represented by the relative value which sets the light emission area of thesample 1 to 100.
その後、ΔＰＬとΔＥＬとの各値の比（ΔＰＬ／ΔＥＬ）を算出した。
算出結果を表２に示す。
なお、発光領域は、サンプル１の発光領域を１００と設定する相対値で表した。USB spectrum (manufactured by Ocean Optics) was used for PL spectrum measurement, and the spectrum measurement was performed under conditions of room temperature (23 ° C.) and excitation wavelength of 365 nm. The spectrum measurement after the drive was performed within 2 hours from that time after the EL was driven until the initial luminance became about half.
Thereafter, the ratio of each value between ΔPL and ΔEL (ΔPL / ΔEL) was calculated.
Table 2 shows the calculation results.
In addition, the light emission area | region was represented by the relative value which sets the light emission area of the
（３）発光寿命
有機ＥＬ素子を室温下、２．５ｍＡ／ｃｍ２の定電流条件下による連続発光を行い、初期輝度の半分の輝度になるのに要する時間（τ１／２）を測定した。
評価結果を表２に示す。
なお、発光寿命は、サンプル１を１００と設定する相対値で表した。(3) Luminous Lifetime The organic EL element was continuously emitted at room temperature under a constant current condition of2.5 mA / cm2 , and the time (τ1 / 2) required to obtain half the initial luminance was measured.
The evaluation results are shown in Table 2.
The light emission lifetime was expressed as a relative value in whichSample 1 was set to 100.
有機ＥＬ素子を室温下、２．５ｍＡ／ｃｍ２の定電流条件下による連続発光を行い、初期輝度の半分の輝度になるのに要する時間（τ１／２）を測定した。
評価結果を表２に示す。
なお、発光寿命は、サンプル１を１００と設定する相対値で表した。(3) Luminous Lifetime The organic EL element was continuously emitted at room temperature under a constant current condition of2.5 mA / cm2 , and the time (τ1 / 2) required to obtain half the initial luminance was measured.
The evaluation results are shown in Table 2.
The light emission lifetime was expressed as a relative value in which
（４）まとめ
表２に示すとおり、本発明の有機ＥＬ素子３～１０は、比較例の有機ＥＬ素子１，２と比較して、駆動電圧、発光領域、発光効率および発光寿命のいずれの点においても優れていた。
このことから、発光層がホスト化合物とヘテロドーパントを含み、発光層のホスト化合物のＬＵＭＯ（Ｈ）準位とドーパントの配位子のうち最も低いＬＵＭＯ（Ｌｍｉｎ）準位との関係、配位子のＬＵＭＯ（Ｌｍｉｎ）準位と発光層の陰極側隣接層の構成材料のＬＵＭＯ（Ｃ）準位と発光層のホスト化合物のＬＵＭＯ（Ｈ）準位との関係を規定することが、電圧上昇がなく、発光効率が高く、寿命を向上させた有機ＥＬ素子を提供するのに有用であることがわかる。また、発光領域を拡大させることにも有用である。(4) Summary As shown in Table 2, the organic EL elements 3 to 10 of the present invention are not compared with theorganic EL elements 1 and 2 of the comparative example in terms of driving voltage, light emitting region, light emission efficiency, and light emission lifetime. Was also excellent.
From this, the light emitting layer contains a host compound and a heterodopant, and the relationship between the LUMO (H) level of the host compound of the light emitting layer and the lowest LUMO (Lmin ) level among the ligands of the dopant, the coordination It is possible to define the relationship between the LUMO (Lmin ) level of the child, the LUMO (C) level of the constituent material of the cathode side adjacent layer of the light emitting layer, and the LUMO (H) level of the host compound of the light emitting layer. It turns out that it is useful for providing the organic EL element which does not raise | lift, has high luminous efficiency, and improved the lifetime. It is also useful for expanding the light emitting region.
表２に示すとおり、本発明の有機ＥＬ素子３～１０は、比較例の有機ＥＬ素子１，２と比較して、駆動電圧、発光領域、発光効率および発光寿命のいずれの点においても優れていた。
このことから、発光層がホスト化合物とヘテロドーパントを含み、発光層のホスト化合物のＬＵＭＯ（Ｈ）準位とドーパントの配位子のうち最も低いＬＵＭＯ（Ｌｍｉｎ）準位との関係、配位子のＬＵＭＯ（Ｌｍｉｎ）準位と発光層の陰極側隣接層の構成材料のＬＵＭＯ（Ｃ）準位と発光層のホスト化合物のＬＵＭＯ（Ｈ）準位との関係を規定することが、電圧上昇がなく、発光効率が高く、寿命を向上させた有機ＥＬ素子を提供するのに有用であることがわかる。また、発光領域を拡大させることにも有用である。(4) Summary As shown in Table 2, the organic EL elements 3 to 10 of the present invention are not compared with the
From this, the light emitting layer contains a host compound and a heterodopant, and the relationship between the LUMO (H) level of the host compound of the light emitting layer and the lowest LUMO (Lmin ) level among the ligands of the dopant, the coordination It is possible to define the relationship between the LUMO (Lmin ) level of the child, the LUMO (C) level of the constituent material of the cathode side adjacent layer of the light emitting layer, and the LUMO (H) level of the host compound of the light emitting layer. It turns out that it is useful for providing the organic EL element which does not raise | lift, has high luminous efficiency, and improved the lifetime. It is also useful for expanding the light emitting region.
本発明は、電圧上昇がなく、発光効率、発光寿命に優れた有機ＥＬ素子を提供することに、特に好適に利用することができる。The present invention can be particularly suitably used for providing an organic EL device that does not increase in voltage and has excellent luminous efficiency and luminous lifetime.
１ 発光層
１０ 再結合領域
１２ 発光に寄与しない領域
１６ 非発光領域
１８，２０，２２ 領域DESCRIPTION OFSYMBOLS 1Light emitting layer 10 Recombination area |region 12 Area |region 16 which does not contribute to light emission Non-light emitting area |region
１０ 再結合領域
１２ 発光に寄与しない領域
１６ 非発光領域
１８，２０，２２ 領域DESCRIPTION OF
Claims (7)
- 少なくとも１層の発光層を有する有機エレクトロルミネッセンス素子であって、
前記発光層には、ホスト化合物と構造式Ｌ１Ｌ２Ｌ３Ｍ（Ｌ１～Ｌ３は二座配位子を表し、Ｍは中心金属を表す。）で表されるドーパントとが含有され、
前記ドーパントの配位子Ｌ１～Ｌ３のうち、少なくとも任意に選択した２つは異なっており、
前記発光層のホスト化合物のＬＵＭＯ（Ｈ）準位と、前記ドーパントの配位子Ｌ１～Ｌ３のうち最も低いＬＵＭＯ（Ｌｍｉｎ）準位と、前記発光層の陰極側隣接層の構成材料のＬＵＭＯ（Ｃ）準位との関係が、条件式（ｉ）および（ii）を満たすことを特徴とする有機エレクトロルミネッセンス素子。
０＜ＬＵＭＯ（Ｌｍｉｎ）－ＬＵＭＯ（Ｈ）≦０．５ｅＶ・・・（ｉ）
ＬＵＭＯ（Ｈ）－０．５ｅＶ＜ＬＵＭＯ（Ｃ）＜ＬＵＭＯ（Ｌｍｉｎ）・・・（ii）An organic electroluminescence device having at least one light emitting layer,
The light emitting layer contains a host compound and a dopant represented by the structural formula L1 L2 L3 M (where L1 to L3 represent a bidentate ligand and M represents a central metal). ,
Of the ligands L1 to L3 of the dopant, at least two arbitrarily selected are different,
The LUMO (H) level of the host compound of the light emitting layer, the lowest LUMO (Lmin ) level among the ligands L1 to L3 of the dopant, and the constituent material of the cathode side adjacent layer of the light emitting layer An organic electroluminescent device characterized in that the relationship with the LUMO (C) level of the above satisfies the conditional expressions (i) and (ii).
0 <LUMO (Lmin ) −LUMO (H) ≦ 0.5 eV (i)
LUMO (H) −0.5 eV <LUMO (C) <LUMO (Lmin ) (ii) - 請求項１に記載の有機エレクトロルミネッセンス素子において、
前記ドーパントが、一般式（２）で表されることを特徴とする有機エレクトロルミネッセンス素子。
「Ｌ′」は「Ｍ」に配位したモノアニオン性の二座配位子のうちの１つまたは複数であり、「Ｍ」は中心金属を表す。ｍ′は１または２の整数を表し、ｎ′は１または２の整数を表すが、ｍ′＋ｎ′は３である。「Ｌ′」は、異なる配位子である。〕The organic electroluminescent device according to claim 1,
The dopant is represented by the general formula (2), an organic electroluminescence element.
“L ′” is one or more of monoanionic bidentate ligands coordinated to “M”, and “M” represents a central metal. m ′ represents an integer of 1 or 2, n ′ represents an integer of 1 or 2, and m ′ + n ′ is 3. “L ′” is a different ligand. ] - 請求項２に記載の有機エレクトロルミネッセンス素子において、
前記一般式（２）で表されるドーパントが、一般式（２－１）で表されることを特徴とする有機エレクトロルミネッセンス素子。
「Ｌ′」は「Ｍ」に配位したモノアニオン性の二座配位子のうちの１つまたは複数であり、「Ｍ」は中心金属を表す。ｍ′は１または２の整数を表し、ｎ′は１または２の整数を表すが、ｍ′＋ｎ′は３である。「Ｌ′」は、異なる配位子である。〕The organic electroluminescence device according to claim 2,
An organic electroluminescence device, wherein the dopant represented by the general formula (2) is represented by the general formula (2-1).
“L ′” is one or more of monoanionic bidentate ligands coordinated to “M”, and “M” represents a central metal. m ′ represents an integer of 1 or 2, n ′ represents an integer of 1 or 2, and m ′ + n ′ is 3. “L ′” is a different ligand. ] - 請求項３に記載の有機エレクトロルミネッセンス素子において、
前記一般式（２－１）で表されるドーパントが、一般式（２－２）で表されることを特徴とする有機エレクトロルミネッセンス素子。
An organic electroluminescence device, wherein the dopant represented by the general formula (2-1) is represented by the general formula (2-2). - 請求項１～４のいずれか一項に記載の有機エレクトロルミネッセンス素子において、
前記ホスト化合物が、一般式（３）で表されることを特徴とする有機エレクトロルミネッセンス素子。
The organic electroluminescent device, wherein the host compound is represented by the general formula (3). - 請求項１に記載の有機エレクトロルミネッセンス素子において、
前記発光層が、少なくとも２層からなり、
前記ドーパントが含有されている発光層に隣接する他の発光層には、前記ドーパントよりも長波長の発光を示すドーパントが含有されていることを特徴とする有機エレクトロルミネッセンス素子。The organic electroluminescent device according to claim 1,
The light emitting layer comprises at least two layers,
The other light emitting layer adjacent to the light emitting layer containing the dopant contains a dopant that emits light having a wavelength longer than that of the dopant. - 請求項１に記載の有機エレクトロルミネッセンス素子において、
発光色が白色であることを特徴とする有機エレクトロルミネッセンス素子。The organic electroluminescent device according to claim 1,
An organic electroluminescence device characterized in that the emission color is white.
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