A kind of quantum dot film and light emitting diode with quantum dotsTechnical field
The present invention relates to quantum dot light emitting devices field more particularly to a kind of quantum dot film and two poles of quantum dot light emittingPipe.
Background technique
Quantum dot is a kind of special material for being limited in nanometer scale in three dimensions, this significantQuantum confined effect makes quantum dot be provided with many unique nanometer properties: launch wavelength is continuously adjustable, emission wavelength is narrow, inhalesReceive spectral width, luminous intensity height, fluorescence lifetime length and good biocompatibility etc..These features mark quantum dot in biologyThe fields such as note, FPD, solid-state lighting, photovoltaic solar all have broad application prospect.
In the semiconductor-quantum-point material system of photoelectric field, cadmium-free quantum dots are due to not only having quantum dot excellentThe characteristics of luminescence and be free of heavy metal cadmium (Cd) simultaneously, have the characteristics that environment-friendly and green and more and more attention has been paid to.But in the effect that shinesIn the photovoltaic applications such as rate and luminance purity (shine peak width) in very important Indexes Comparison, the performance of cadmium-free quantum dots is alsoIt is that significant can lag behind classical cadmium content point system (such as CdSe).What the preparation of cadmium-free quantum dots generallyd use at present be withCadmium content puts similar metallorganic and thermally decomposes hot injection method, upper similarly using core-shell structure in quantum-dot structure designTo improve the luminous efficiency and stability of material of cadmium-free quantum dots.
In the cadmium-free quantum dots core-shell structure generallyd use at present, mainly using the alloy of ZnS, ZnSe or bothChange structure ZnSeS as shell structurre, but the shell structurre due to mentioned component and cadmium-free quantum dots core (such as InP) exist significantlyLattice mismatch, and since the inconsistent of crystal structure can not reduce this crystalline substance by the method for making nucleocapsid that alloying occurLattice mismatch, thus realizing can be smaller than cadmium content point compared with the shell thickness of excellent quantum dot performance, whole cadmium-free quantum dots nucleocapsid knotThe partial size of structure is generally in 4-5 ran, and the partial size one of the cadmium content point used in quantum dot display technology at presentAs all at 8 nanometers or more.
The characteristics of shell layer and small particle of cadmium-free quantum dots core-shell structure, can make quantum dot form solid filmAfterwards, since the interaction between strong quantum dot causes mutual fluorescence resonance energy transfer (Forster ResonantEnergy Transfer, is abbreviated as FRET), the significant decrease of thin-film light emitting efficiency is caused, and as mentioned, increase shellThickness degree increases whole partial size in turn will cause being greatly reduced for quantum dot itself luminous efficiency again.This film of cadmium-free quantum dotsLow luminous efficiency thus also result in the poor efficiency of corresponding QLED device.
Therefore, existing cadmium-free quantum dots film and corresponding QLED device architecture Shortcomings and problem need furtherImprove.
Summary of the invention
In view of above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide a kind of quantum dot film and quantum dot light emittingsDiode, it is intended to solve existing cadmium-free quantum dots film since stronger interaction causes serious FRET effect to lead to filmThe problem of luminous efficiency is greatly reduced, and corresponding light emitting diode with quantum dots luminous efficiency is also greatly reduced.
Technical scheme is as follows:
A kind of quantum dot film, wherein including cadmium-free quantum dots and the interval quantum dot being dispersed between the cadmium-free quantum dots；
The cadmium-free quantum dots are the cadmium-free quantum dots of core-shell structure；
Form the metallic element of the interval quanta point material and the metallic element for the Shell Materials for forming the cadmium-free quantum dotsPositioned at same family；Form the nonmetalloid of the interval quanta point material and the Shell Materials for forming the cadmium-free quantum dotsNonmetalloid is located at same family.
A kind of light emitting diode with quantum dots, the light emitting diode with quantum dots include quantum dot light emitting layer, wherein the amountSon point luminescent layer is quantum dot film of the present invention.
The utility model has the advantages that the present invention is spaced quantum dot by being added, the distance between cadmium-free quantum dots can be effectively increased, fromAnd effectively weaken the interaction between cadmium-free quantum dots and resulting FRET effect, to promote quantum dot filmLuminous efficiency；And it is dramatically different come the mode for increasing mutual distance between cadmium-free quantum dots with other interval insulants are addedIt is that the interval quantum dot uses the structure of composition same or similar with cadmium-free quantum dots outer shell, it is ensured that entire quantumCoherence and continuity of the point film on energy level, i.e. interval quantum dot still are able to provide to the effective energy level beam of cadmium-free quantum dotsIt ties up, the energy level of the original outer shell of the cadmium-free quantum dots that extended fetters effect, but will not introduce additional lattice mismatch；With widthThe interval quantum dot of band gap can be realized the energy transmission to no cadmium luminescent quantum dot, makes full use of and is injected into quantum dot layerCharge and the exciton of generation；In addition, having wide bandgap, that is, high-energy photons interval quantum dot to can be realized to no cadmium amountThe energy transmission of son point, makes full use of the exciton of the charge and generation that are injected into quantum dot layer；Finally, interval quantum dot canGap when effectively filling film is formed, realizes the quantum dot film smooth, compactness is good.
Detailed description of the invention
Fig. 1 is a kind of structural schematic diagram of quantum dot film provided by the invention.
Fig. 2 is the light emitting diode with quantum dots of the invention containing hole injection layer, hole transmission layer and electron transfer layerStructural schematic diagram.
Fig. 3 is the structural schematic diagram of the light emitting diode with quantum dots in the embodiment of the present invention 7.
Fig. 4 is the structural schematic diagram of the light emitting diode with quantum dots in the embodiment of the present invention 8.
Fig. 5 is the structural schematic diagram of the light emitting diode with quantum dots in the embodiment of the present invention 9.
Specific embodiment
The present invention provides a kind of quantum dot film and light emitting diode with quantum dots, to make the purpose of the present invention, technical solutionAnd effect is clearer, clear, the present invention is described in more detail below.It should be appreciated that specific implementation described hereinExample is only used to explain the present invention, is not intended to limit the present invention.
The present invention provides a kind of quantum dot film, wherein as shown in Figure 1, including cadmium-free quantum dots 1 and being dispersed in the nothingInterval quantum dot 2 between cadmium quantum dot 1.That is, in the quantum dot film it is evenly dispersed have cadmium-free quantum dots 1 andEvery quantum dot 2.The cadmium-free quantum dots 1 are the cadmium-free quantum dots of core-shell structure；Form the metal of interval 2 material of quantum dotThe metallic element of element and the Shell Materials of the composition cadmium-free quantum dots 1 is located at same family；Form 2 material of interval quantum dotThe nonmetalloid of the Shell Materials of the nonmetalloid and composition cadmium-free quantum dots 1 of material is located at same family.It should be notedThe metallic element for being the metallic element and the Shell Materials for forming the cadmium-free quantum dots that form the interval quanta point material canThink the same metallic element in same family, or with two different metallic elements in family.Between composition is describedEvery the nonmetalloid of the Shell Materials of the nonmetalloid and composition cadmium-free quantum dots of quanta point material can be sameSame nonmetalloid in race, or with two different nonmetalloids in family.
In a preferred embodiment, the Shell Materials of the material of the interval quantum dot and the cadmium-free quantum dotsIt is Group II-VI semiconductor material.Further in a preferred embodiment, the interval quantum dot is mononuclear structure amountIt is sub-, it shines because the interval quantum dot of nucleocapsid mechanism can generate itself, and core-shell structure can be easy to hold onto charge and causeLoss, it is described interval quantum dot material and the cadmium-free quantum dots Shell Materials be selected from ZnSe, ZnS, ZnTe, ZnSeS,One of ZnSeTe and ZnSTe.Further in a preferred embodiment, the material of the interval quantum dot and instituteThe Shell Materials for stating cadmium-free quantum dots are selected from one of ZnS, ZnSe and ZnSeS.
It should be noted that the material of the interval quantum dot and the Shell Materials of the cadmium-free quantum dots can be II-VI(the i.e. described interval quantum dot and the shell of the cadmium-free quantum dots have phase to same semiconductor material in race's semiconductor materialSame material composition), or two different semiconductor materials (i.e. described amount of space in Group II-VI semiconductor materialSon point and the shell of the cadmium-free quantum dots are formed with similar material).For example, the shell when the cadmium-free quantum dots isWhen ZnSe in Group II-VI semiconductor material, the interval quantum dot can using the ZnSe in Group II-VI semiconductor material,The i.e. described interval quantum dot is formed using material identical with the shell of the cadmium-free quantum dots；When the shell of the cadmium-free quantum dotsWhen layer is the ZnSe in Group II-VI semiconductor material, the interval quantum dot can also be using in Group II-VI semiconductor materialZnS or ZnSeS etc., i.e., the described interval quantum dot is using the composition of material similar in the shell with the cadmium-free quantum dots.
The present invention is directed in traditional cadmium-free quantum dots film, and interacting since cadmium-free quantum dots are stronger, it is serious to causeFRET effect, improves quantum dot film at the problem of causing thin-film light emitting efficiency to be greatly reduced, and passes through and interval quantum is addedPoint can effectively increase the distance between cadmium-free quantum dots, thus effectively weaken cadmium-free quantum dots between interaction withAnd resulting FRET effect, to promote the luminous efficiency of quantum dot film；And increase with other interval insulants are addedAdd the mode of mutual distance between cadmium-free quantum dots dramatically different, the interval quantum dot uses and cadmium-free quantum dots shellThe structure of the same or similar composition of layer, it is ensured that entire coherence and continuity of the quantum dot film on energy level is spacedQuantum dot still is able to provide and fetter to the effective energy level of cadmium-free quantum dots, the energy level beam of the original outer shell of the cadmium-free quantum dots that extendedEffect is tied up, but additional lattice mismatch will not be introduced；Interval quantum dot with wide bandgap can be realized to shine to no cadmiumThe energy transmission of quantum dot makes full use of the exciton of the charge and generation that are injected into quantum dot layer；In addition, having wide bandgapThat is the interval quantum dot of high-energy photons can be realized the energy transmission to cadmium-free quantum dots, makes full use of and is injected into quantum dot layerCharge and generation exciton；Finally, interval quantum dot can effectively fill gap when film is formed, smooth, cause is realizedThe good quantum dot film of close property.
Cadmium-free quantum dots of the present invention are the cadmium-free quantum dots of core-shell structure, and no cadmium amount can be improved using core-shell structureThe luminous efficiency and stability of material of son point.In a preferred embodiment, the nuclear material of the cadmium-free quantum dots isIII-V group semi-conductor material.As an example, the III-V group semi-conductor material be selected from GaN, GaP, GaAs, InP, InAs,One of InAsP, GaAsP, InGaP, InGaAs and InGaAsP etc..
In a preferred embodiment, the partial size of the interval quantum dot is 2-5nm.By adjusting interval quantum dotPartial size, the promotion of quantum dot film luminous efficiency may be implemented.
In a preferred embodiment, the partial size of the cadmium-free quantum dots is 3-6nm.
In a preferred embodiment, mole of the cadmium-free quantum dots and interval quantum dot in quantum dot filmRatio is (1:0.5)-(1:4).By adjusting the mixed proportion of two amounts sub- point, quantum dot film luminous efficiency may be implementedIt is promoted.
In a preferred embodiment, the quantum dot film with a thickness of 10-80nm.
The present invention also provides a kind of preparation methods of quantum dot film comprising step: first by cadmium-free quantum dots andIt is mixed in non-polar organic solvent, and is uniformly mixed every quantum dot, obtain mixing quantum dot solution；It then will by solwution methodQuantum dot film is made in the mixing quantum dot solution；Wherein the cadmium-free quantum dots are the cadmium-free quantum dots of core-shell structure, groupIt is located at the metallic element of the interval quanta point material and the metallic element for the Shell Materials for forming the cadmium-free quantum dots sameFamily；Form the nonmetallic of the nonmetalloid of the interval quanta point material and the Shell Materials of the composition cadmium-free quantum dotsElement is located at same family.
Solwution method of the present invention can be without being limited thereto for spin-coating method, ink-jet printing etc..As an example, the nonpolarityOrganic solvent can selected from chloroform, toluene, chlorobenzene, n-hexane, normal octane, decahydronaphthalene and tridecane etc. it is without being limited thereto in oneKind.
The present invention also provides a kind of light emitting diode with quantum dots, the light emitting diode with quantum dots includes quantum dot light emittingLayer, wherein the quantum dot light emitting layer is quantum dot film of the present invention.In a preferred embodiment, the amountSon point film with a thickness of 10-80nm.
There are many forms for light emitting diode with quantum dots in the prior art, and the present invention will be mainly with quantum dot as shown in Figure 2Light emitting diode is introduced for embodiment.Specifically, as shown in Fig. 2, the light emitting diode with quantum dots includes from the bottom upSubstrate, transparent conductive anode, hole injection layer, hole transmission layer, quantum dot light emitting layer, electron transfer layer and the yin of lamination settingPole.Wherein the quantum dot light emitting layer is quantum dot film of the present invention.
In a preferred embodiment, the quantum dot light emitting layer with a thickness of 10-80nm.The quantum under the thicknessThe luminous efficiency of point Light-Emitting Diode is higher.
In a preferred embodiment, the substrate can be without being limited thereto for glass, PET or PI etc..
In a preferred embodiment, the transparent conductive anode can be selected from indium doping tin oxide (ITO), Fluorin dopedOne of tin oxide (FTO), antimony-doped tin oxide (ATO), aluminium-doped zinc oxide (AZO) are a variety of.
In a preferred embodiment, the material of the hole injection layer can be selected from having good hole injection efficiencyMaterial, such as can be but be not limited to poly- (3,4-rthylene dioxythiophene)-polystyrolsulfon acid (PEDOT:PSS), CuPc(CuPc), tetra- cyanogen quinone of 2,3,5,6- tetra- fluoro- 7,7', 8,8'--bismethane (F4-TCNQ), six cyano -1 2,3,6,7,10,11-,Six azepine benzophenanthrene (HATCN) of 4,5,8,9,12-, doped or non-doped transition metal oxide, doped or non-doped metal sulphurOne of based compound is a variety of；Wherein, the transition metal oxide includes but is not limited to MoO3、VO2、WO3, in CuOIt is one or more；The metal chalcogenide includes but is not limited to MoS2、MoSe2、WS2、WSe2, one of CuS or moreKind.In a preferred embodiment, the hole injection layer with a thickness of 10-150nm.
In a preferred embodiment, the material of the hole transmission layer can be selected from having good cavity transmission abilityOrganic material, such as can be but be not limited to poly- (9,9- dioctyl fluorene-CO-N- (4- butyl phenyl) diphenylamines) (TFB), poly-Vinyl carbazole (PVK), poly- (bis- bis- (phenyl) benzidine of (4- butyl phenyl)-N, N'- of N, N') (Poly-TPD), poly- (9,9- bis-Double-the N of octyl fluorenes -co-, N- phenyl -1,4- phenylenediamine) (PFB), 4,4 ', 4 ' '-three (carbazole -9- base) triphenylamine (TCTA), 4,4'- bis- (9- carbazole) biphenyl (CBP), N, N '-diphenyl-N, N '-two (3- aminomethyl phenyl) -1,1 '-biphenyl -4,4 '-diamines(TPD), N, N '-diphenyl-N, N '-(1- naphthalene) -1,1 '-biphenyl -4,4 '-diamines (NPB), doped graphene, undoped stoneOne of black alkene, C60 or a variety of.In a preferred embodiment, the hole transmission layer with a thickness of 10-150nm.
In a preferred embodiment, the material of the electron transfer layer can be selected from good electron-transportingCan material, such as can be but be not limited to ZnO, TiO of N-shaped2、Fe2O3、SnO2、Ta2O3, in AlZnO, ZnSnO, InSnO etc.It is one or more.Further in a preferred embodiment, the material of the electron transfer layer is selected from ZnO, n of N-shapedThe TiO of type2One of.In a preferred embodiment, the electron transfer layer with a thickness of 10-150nm.
In a preferred embodiment, the cathode can be selected from aluminium (Al) electrode, silver (Ag) electrode, gold (Au) electrodeOne of.In a preferred embodiment, the cathode with a thickness of 30-800nm.
The present invention also provides a kind of preparation methods of light emitting diode with quantum dots as described above, comprising the following steps:
One substrate is provided, forms transparent conductive anode over the substrate；
Hole injection layer, hole transmission layer, quantum dot light emitting layer and electron-transport are sequentially depositing on the transparent conductive anodeLayer；Wherein the quantum dot light emitting layer is quantum dot film of the present invention；
The light emitting diode with quantum dots is prepared in evaporation cathode on the electron transport layer.
In the present invention, each deposition method can be chemical method or physical method, and wherein chemical method includes but is not limited to chemistryOne of vapour deposition process, successive ionic layer adsorption and reaction method, anodizing, strike, coprecipitation are moreKind；Physical method includes but is not limited to spin-coating method, print process, knife coating, dip-coating method, infusion method, spray coating method, roll coating process, poursCasting, slit coating method, strip rubbing method, thermal evaporation coating method, electron beam evaporation deposition method, magnetron sputtering method, multi sphere fromOne of sub- coating method, physical vaporous deposition, atomic layer deposition method, pulsed laser deposition are a variety of.
Below by embodiment, the present invention is described in detail.
The pure quantum dot film (contrast groups) of embodiment 1:InP/ZnS cadmium-free quantum dots
(1) choose glow peak wavelength be 520nm, the InP/ZnS for the core-shell structure that partial size 4.6nm, solution quantum yield are 62%Cadmium-free quantum dots；
(2) InP/ZnS cadmium-free quantum dots are added in normal octane solution and are sufficiently mixed uniformly, forming mass concentration is 30mg/The quantum dot solution of mL；
(3) quantum dot solution is formed into film by way of spin coating；
(4) the quantum yield test result of film is 17%.
The quantum dot film of embodiment 2:InP/ZnS cadmium-free quantum dots and ZnS quantum dot (small particle)
(1) choose glow peak wavelength be 520nm, the InP/ZnS for the core-shell structure that partial size 4.6nm, solution quantum yield are 62%Cadmium-free quantum dots；
(2) it chooses the ZnS oil phase quantum dot that partial size is 2.1nm and is used as interval quantum dot；
(3) InP/ZnS cadmium-free quantum dots and the interval ZnS quantum dot are added in normal octane solution sufficiently with the molar ratio of 1:2It is uniformly mixed, forms the mixing quantum dot solution that mass concentration is 30mg/mL；
(4) mixing quantum dot solution is formed into film by way of spin coating；
(5) the quantum yield test result of film is 34%.
The quantum dot film of embodiment 3:InP/ZnS cadmium-free quantum dots and ZnS quantum dot (big partial size)
(1) choose glow peak wavelength be 520nm, the InP/ZnS for the core-shell structure that partial size 4.6nm, solution quantum yield are 62%Cadmium-free quantum dots；
(2) it chooses the ZnS oil phase quantum dot that partial size is 4.7nm and is used as interval quantum dot；
(3) InP/ZnS cadmium-free quantum dots and the interval ZnS quantum dot are added in normal octane solution sufficiently with the molar ratio of 1:2It is uniformly mixed, forms the mixing quantum dot solution that mass concentration is 30mg/mL；
(4) mixing quantum dot solution is formed into film by way of spin coating；
(5) the quantum yield test result of film is 14%.Show after compared with Examples 1 and 2 result when the interval of selectionIt is unsuitable excessively high with the mixed proportion of cadmium-free quantum dots when quantum point grain diameter is larger.
The quantum dot film of embodiment 4:InP/ZnS cadmium-free quantum dots and ZnS quantum dot (big partial size)
(1) choose glow peak wavelength be 520nm, the InP/ZnS for the core-shell structure that partial size 4.6nm, solution quantum yield are 62%Cadmium-free quantum dots；
(2) it chooses the ZnS oil phase quantum dot that partial size is 4.7nm and is used as interval quantum dot；
(3) InP/ZnS cadmium-free quantum dots and the interval ZnS quantum dot are added in normal octane solution with the molar ratio of 1:0.8 and are filledDivide and be uniformly mixed, forms the mixing quantum dot solution that mass concentration is 30mg/mL；
(4) mixing quantum dot solution is formed into film by way of spin coating；
(5) the quantum yield test result of film is 25%.Show the interval quantum when selection after compared with 3 result of embodimentWhen point partial size is larger, after the mixed proportion by adjusting two amounts sub- point, quantum dot film luminous efficiency equally may be implementedIt is promoted.
The quantum dot film of embodiment 5:InP/ZnSe cadmium-free quantum dots and ZnSe quantum dot
(1) choose glow peak wavelength be 613nm, the InP/ for the core-shell structure that partial size 5.1nm, solution quantum yield are 57%ZnSe cadmium-free quantum dots；
(2) it chooses the ZnSe oil phase quantum dot that partial size is 3.6nm and is used as interval quantum dot；
(3) InP/ZnSe cadmium-free quantum dots and the interval ZnSe quantum dot are added in normal octane solution with the molar ratio of 1:1 and are filledDivide and be uniformly mixed, forms the mixing quantum dot solution that mass concentration is 30mg/mL；
(4) mixing quantum dot solution is formed into film by way of spin coating；
(5) the quantum yield test result of film is 31%.
The quantum dot film of embodiment 6:InP/ZnSe cadmium-free quantum dots and ZnS quantum dot
(1) choose glow peak wavelength be 613nm, the InP/ for the core-shell structure that partial size 5.1nm, solution quantum yield are 57%ZnSe cadmium-free quantum dots；
(2) it chooses the ZnS oil phase quantum dot that partial size is 2.1nm and is used as interval quantum dot；
(3) InP/ZnSe cadmium-free quantum dots and the interval ZnS quantum dot are added in normal octane solution with the molar ratio of 1:1.5 and are filledDivide and be uniformly mixed, forms the mixing quantum dot solution that mass concentration is 30mg/mL；
(4) mixing quantum dot solution is formed into film by way of spin coating；
(5) the quantum yield test result of film is 35%.
Embodiment 7: positive bottom set emissive quantum dots light emitting diode
The present embodiment light emitting diode with quantum dots, as shown in figure 3, successively include: from bottom to top ITO substrate 11, hearth electrode 12,PEDOT:PSS hole injection layer 13, poly-TPD hole transmission layer 14, quantum dot light emitting layer 15, ZnO electron transfer layer 16 and AlTop electrode 17.
The preparation step of above-mentioned light emitting diode with quantum dots is as follows:
It is empty that hearth electrode 12,30nm PEDOT:PSS hole injection layer 13 and 30nm poly-TPD are sequentially prepared on ITO substrate 11After cave transport layer 14, one layer of quantum dot light emitting layer 15 is prepared on poly-TPD hole transmission layer 14 and is then existed with a thickness of 20nm40nm ZnO electron transfer layer 16 and 100nm Al top electrode 17 are sequentially prepared on quantum dot light emitting layer 15.The quantum dot light emittingLayer 15 is quantum dot film as described in Example 2.
Embodiment 8: positive bottom set emissive quantum dots light emitting diode
Light emitting diode with quantum dots in the present embodiment, as shown in figure 4, successively include: from bottom to top ITO substrate 21, hearth electrode 22,PEDOT:PSS hole injection layer 23, Poly (9-vinylcarbazole) (PVK) hole transmission layer 24, quantum dot light emitting layer25, ZnO electron transfer layer 26 and Al top electrode 27.
The preparation step of above-mentioned light emitting diode with quantum dots is as follows:
Hearth electrode 22,30nm PEDOT:PSS hole injection layer 23 and the hole 30nm PVK is sequentially prepared on ITO substrate 21 to passAfter defeated layer 24, one layer of quantum dot light emitting layer 25 is prepared on PVK hole transmission layer 24, with a thickness of 20nm, is then sent out in quantum dot40nm ZnO electron transfer layer 26 and 100nm Al top electrode 27 are sequentially prepared on photosphere 25.The quantum dot light emitting layer 25 is such asQuantum dot film as described in example 4.
Embodiment 9: positive bottom set emissive quantum dots light emitting diode
The present embodiment light emitting diode with quantum dots, as shown in figure 5, successively include: from bottom to top ITO substrate 31, hearth electrode 32,PEDOT:PSS hole injection layer 33, poly-TPD hole transmission layer 34, quantum dot light emitting layer 35, TPBi electron transfer layer 36 andAl top electrode 37.
The preparation step of above-mentioned light emitting diode with quantum dots is as follows:
It is empty that hearth electrode 32,30nm PEDOT:PSS hole injection layer 33 and 30nm poly-TPD are sequentially prepared on ITO substrate 31After cave transmitting layer 34, one layer of quantum dot light emitting layer 35 is prepared on poly-TPD hole transmission layer 34 and is then existed with a thickness of 20nm30nm TPBi electron transfer layer 36 and 100nm Al top electrode are sequentially prepared by vacuum deposition method on quantum dot light emitting layer 3537.The quantum dot light emitting layer 35 is quantum dot film as described in Example 5.
In conclusion the present invention is spaced quantum dot by being added, the distance between cadmium-free quantum dots can be effectively increased, fromAnd effectively weaken the interaction between cadmium-free quantum dots and resulting FRET effect, to promote cadmium-free quantum dotsThe luminous efficiency of film；And increase the mode of mutual distance between cadmium-free quantum dots significantly not with other interval insulants are addedWith the interval quantum dot uses the structure of composition same or similar with cadmium-free quantum dots outer shell, it is ensured that entireCoherence and continuity of the quantum dot film on energy level, i.e. interval quantum dot still are able to provide to the effective energy of cadmium-free quantum dotsThe energy level of grade constraint, the original outer shell of the cadmium-free quantum dots that extended fetters effect, but will not introduce additional lattice mismatch；SeparatelyOutside, there is wide bandgap, that is, high-energy photons interval quantum dot can be realized the energy transmission to cadmium-free quantum dots, sufficiently benefitWith the exciton for the charge and generation for being injected into quantum dot layer；Finally, interval quantum dot can be filled effectively when film is formedThe quantum dot film smooth, compactness is good is realized in gap.
It should be understood that the application of the present invention is not limited to the above for those of ordinary skills canWith improvement or transformation based on the above description, all these modifications and variations all should belong to the guarantor of appended claims of the present inventionProtect range.