CN103311453A - Electroluminescent device and preparation method thereof - Google Patents

Abstract

The invention belongs to the field of electroluminescent devices and discloses an electroluminescent device and a preparation method thereof. The electroluminescent device comprises an anode conductive glass substrate, a hole injection layer, a hole transport layer, a luminescent layer, an electron transport layer, an electron injection layer and a cathode layer which are sequentially stacked, wherein the electron injection layer is made of a cesium-salt-doped metal oxide. The organic electroluminescent device provided by the invention is formed by doping cesium salt and a bipolar metal oxide. On one hand, cesium salt has the advantages of low evaporation temperature (about 300 DEG C), high purity, simple source and low price, and on the other hand, bipolar metal oxide has good electron transport capacity and stable property, is not easily oxidized and is suitable to be evaporated together with cesium salt. Electron injection and transport capacities can be simultaneously improved, and an evaporated nanostructure can reflect and scatter light to some extent. Therefore, light emitted out from the top can be reflected to and emitted out from the bottom, and the light extraction efficiency can be further improved.

Description

A kind of electroluminescent device and preparation method thereof

Technical field

The present invention relates to electroluminescent device, relate in particular to a kind of electroluminescent device and preparation method thereof.

Background technology

1987, the C.W.Tang of U.S. Eastman Kodak company and VanSlyke reported the breakthrough in the organic electroluminescent research.Utilize the ultrathin film technology to prepare high brightness, high efficiency double-deck electroluminescent device (OLED).In this double-deck device, brightness reaches 1000cd/m under the 10V², its luminous efficiency is that 1.51lm/W, life-span were greater than 100 hours.

The principle of luminosity of OLED is based under the effect of extra electric field, and electronics is injected into organic lowest unocccupied molecular orbital (LUMO) from negative electrode, and the hole is injected into organic highest occupied molecular orbital (HOMO) from anode.Electronics and hole meet at luminescent layer, compound, form exciton, exciton moves under electric field action, and energy is passed to luminescent material, and excitation electron is from the ground state transition to excitation state, excited energy produces photon by the radiation inactivation, release luminous energy.

In traditional organic electroluminescence device, generally adopt LiF (lithium fluoride) as the electron injecting layer of device.This material can effectively improve the injectability of electronics, thereby improves the recombination probability in electronics and hole, still, thickness is generally below the 1nm, and there is certain difficulty in evaporation, difficult control thickness, the reappearance of finished product is affected, if too thick, the resistance of device is sharply risen, luminous efficiency also descends thereupon, if it is too thin, then do not form good Ohmic contact, the electronics injectability can not be improved significantly, and causes light extraction efficiency low; In addition, the LiF evaporating temperature is higher, and about 800 ℃, in evaporate process, very easily form degassing phenomenon, thereby cause vacuum degree to descend, preparation technology brings certain difficulty to the later stage

Summary of the invention

One of problem to be solved by this invention be to provide a kind of luminance higher, make simple electroluminescent device.

A kind of electroluminescent device comprises the anode conducting substrate of glass, hole injection layer, hole transmission layer, luminescent layer, electron transfer layer, electron injecting layer and the cathode layer that stack gradually; Wherein, the material of described electron injecting layer is the doped metallic oxide cesium salt, and the doping mass percent of cesium salt is 1～10%; The thickness of described electron injecting layer is 5～20nm.

In the described electroluminescent device, the material of each functional layer is as follows:

Described anode conducting substrate of glass is selected from indium tin oxide glass, mix the zinc oxide glass of aluminium or mix the zinc oxide glass of indium;

The material of described hole injection layer is selected from molybdenum trioxide, tungstic acid or vanadic oxide;

The material of described hole transmission layer is selected from 1,1-two [4-[N, N '-two (p-tolyl) amino] phenyl] cyclohexane, 4,4 ', 4 " three (carbazole-9-yl) triphenylamine, N, N '-(1-naphthyl)-N, N '-diphenyl-4,4 '-benzidines;

To be dopant material be doped to the composite material of forming in the material of main part according to the ratio of mass percent 1～20% to the material of described luminescent layer; Wherein, dopant material is selected from two (4,6-difluorophenyl pyridine-N, C²) the pyridine formyl closes iridium, two (2-methyl-diphenyl [f, h] quinoxaline) (acetylacetone,2,4-pentanedione) and close iridium or three (2-phenylpyridine) and close iridium); Material of main part is selected from 1,1-two [4-[N, N '-two (p-tolyl) amino] phenyl] cyclohexane, 4,4 ', 4 " three (carbazole-9-yl) triphenylamine, N, N '-(1-naphthyl)-N, N '-diphenyl-4,4 '-benzidines;

The material of described electron transfer layer is selected from 4,7-diphenyl-1,10-phenanthroline, 1,2,4-triazole derivative or N-aryl benzimidazole;

Described metal oxide is selected from manganese oxide, tungsten oxide or molybdenum oxide;

Described cesium salt is selected from cesium carbonate, cesium fluoride or nitrine caesium;

The material of described cathode layer is selected from silver, aluminium, platinum or gold.

Two of problem to be solved by this invention is to provide the preparation method of above-mentioned electroluminescent device, comprises the steps;

S1, the anode conducting substrate of glass is carried out photoetching treatment, use liquid detergent, deionized water, acetone, ethanol, each ultrasonic cleaning 15min of isopropyl alcohol subsequently successively, remove organic pollution;

S2, will clean up back antianode electro-conductive glass suprabasil anode layer and carry out oxygen plasma treatment, the processing time is 5-15min, and power is 10-50W;

S3, employing evaporation process stack gradually evaporation hole injection layer, hole transmission layer, luminescent layer, electron transfer layer, electron injecting layer and cathode layer on the anode layer surface of anode conducting substrate of glass; Wherein, the material of described electron injecting layer is the doped metallic oxide cesium salt, and the doping mass percent of cesium salt is 1～10%; The thickness of described electron injecting layer is 5～20nm;

After above-mentioned processing step is finished, make electroluminescent device.

Electroluminescent device provided by the invention, cesium salt and bipolarity metal oxide mix, on the one hand, the evaporating temperature of cesium salt is lower, cheap, and the electron transport ability of bipolarity metal oxide is better, stable in properties, be fit to carry out common steaming with cesium salt, can improve simultaneously that electronics injects and transmittability, and the nanostructure that evaporation comes out there are certain reflection and scattering process to light, therefore, the light of top outgoing can be reflexed to the bottom outgoing, further improve light extraction efficiency.

The preparation method of electroluminescent device provided by the invention, its preparation technology is simple, processing cost is low, is fit to commercially produce.

Description of drawings

Fig. 1 is the concrete electroluminescent device structural representation of implementing;

Brightness and luminous efficiency graph of a relation between the electroluminescent device that Fig. 2 makes for embodiment 1 and the electroluminescent device of Comparative Examples.

Embodiment

The electroluminescent device that this embodiment provides as shown in Figure 1, comprises the anode conducting substrate ofglass 11,hole injection layer 12,hole transmission layer 13,luminescent layer 14,electron transfer layer 15,electron injecting layer 16 and thecathode layer 17 that stack gradually; Wherein, anode conducting substrate ofglass 11 comprisesanode layer 112 and substrate ofglass 111; The material of described electron injectinglayer 16 is for being material of main part doping cesium salt (be that metal oxide is material of main part, cesium salt is dopant material) with the metal oxide, and the doping mass percent of cesium salt is 1～10%; The thickness of described electron injecting layer is 5～20nm, and preferred thickness is 10nm.

Electroluminescent device described above, material and the thickness of each functional layer are as follows:

Anode conducting substrate ofglass 11 is selected from indium tin oxide glass, mix the zinc oxide glass of aluminium or mix the zinc oxide glass of indium, and itsanode layer 112 is respectively indium tin oxide (ITO), mix the zinc oxide (AZO) of aluminium, mix the zinc oxide (IZO) of indium; Therefore, indium tin oxide glass, the zinc oxide glass of mixing aluminium, the zinc oxide glass of mixing indium are called for short ito glass, AZO glass, IZO glass respectively;

The material ofhole injection layer 12 is selected from molybdenum trioxide (MoO₃), tungstic acid (WO₃) or vanadic oxide (V₂O₅); The thickness of hole injection layer is 10-40nm, and preferred thickness is 20nm;

The material ofhole transmission layer 13 is selected from 1,1-two [4-[N, N '-two (p-tolyl) amino] phenyl] cyclohexane (TAPC), 4,4 ', 4 " three (carbazole-9-yl) triphenylamine (TCTA), N, N '-(1-naphthyl)-N; N '-diphenyl-4, the preferred NPB of 4 '-benzidine (NPB); The thickness of hole transmission layer is 20-60nm, and preferred thickness is 40nm;

The material ofluminescent layer 14 is selected from two (4,6-difluorophenyl pyridine-N, C²) the pyridine formyl closes iridium (FIrpic), two (2-methyl-diphenyl [f, h] quinoxaline) (acetylacetone,2,4-pentanedione) and close iridium (Ir (MDQ)₂(acac)) or three (2-phenylpyridines) close iridium (Ir (ppy)₃);

Perhaps to be dopant material be doped to the composite material of forming in the material of main part according to the ratio of mass percent 1～20% to the material ofluminescent layer 14; Wherein, dopant material is selected from two (4,6-difluorophenyl pyridine-N, C²) the pyridine formyl closes iridium (FIrpic), two (2-methyl-diphenyl [f, h] quinoxaline) (acetylacetone,2,4-pentanedione) and close iridium (Ir (MDQ)₂(acac)) or three (2-phenylpyridines) close iridium (Ir (ppy)₃); Material of main part is selected from 1,1-two [4-[N, N '-two (p-tolyl) amino] phenyl] cyclohexane (TAPC), 4,4 ', 4 " three (carbazole-9-yl) triphenylamine (TCTA), N, N '-(1-naphthyl)-N, N '-diphenyl-4,4 '-benzidines (NPB);

The thickness ofluminescent layer 14 is 2-30nm;

The material ofluminescent layer 14 is preferably Ir (ppy)₃Be doped among the TCTA, and the doping mass percent is 10% that at this moment, the thickness of luminescent layer is preferably 20nm;

The material ofelectron transfer layer 15 is selected from 4,7-diphenyl-1,10-phenanthroline (Bphen), 1,2, the 4-triazole derivative (as, TAZ) or N-aryl benzimidazole (TPBi); The thickness ofelectron transfer layer 15 is 40-80nm, preferred 60nm;

In the electron injectinglayer 16, described metal oxide is selected from manganese oxide (MnO), tungsten oxide (WO₃) or (MoO₃), described cesium salt is selected from cesium carbonate (Cs₂CO₃), cesium fluoride (CsF) or nitrine caesium (CsN₃);

The material ofcathode layer 17 is selected from silver (Ag), aluminium (Al), platinum (Pt) or gold (Au), is preferably Ag; The thickness of cathode layer is 80～250nm, and preferred thickness is 100nm.

The preparation method of above-mentioned electroluminescent device comprises the steps;

S1, the anode conducting substrate of glass is carried out photoetching treatment, use liquid detergent, deionized water, acetone, ethanol, each ultrasonic cleaning 15min of isopropyl alcohol subsequently successively, remove organic pollution;

S2, will clean up back antianode electro-conductive glass suprabasil anode layer and carry out oxygen plasma treatment, the processing time is 5-15min, and power is 10-50W;

S3, employing evaporation process stack gradually evaporation hole injection layer, hole transmission layer, luminescent layer, electron transfer layer, electron injecting layer and cathode layer on the anode layer surface of anode conducting substrate of glass; Wherein, the material of described electron injecting layer is the doped metallic oxide cesium salt, and the doping mass percent of cesium salt is 1～10%; The thickness of described electron injecting layer is 5～20nm;

After above-mentioned processing step is finished, make electroluminescent device.

Above-mentioned electroluminescent device, mix with cesium salt and bipolarity metal oxide, on the one hand, the evaporating temperature of cesium salt is lower, about 300 ℃, purity is higher, and the source is simple, and is cheap, and the electron transport ability of bipolarity oxide is better, and stable in properties is difficult for taking place oxidation etc., is fit to carry out common steaming with cesium salt, improving electronics simultaneously injects and transmittability, and the nanostructure that evaporation comes out has certain reflection and scattering process to light, therefore, the light of top outgoing can be reflexed to the bottom outgoing, further improve light extraction efficiency, because thickness is the nanoscale scope, so also more easy to control on the evaporation process, be conducive to following suitability for industrialized production.

Below in conjunction with accompanying drawing, preferred embodiment of the present invention is described in further detail.

Following examples, its evaporation process are all in high vacuum coating equipment (scientific instrument development center, Shenyang Co., Ltd, pressure＜1 * 10^-3Pa) carry out in.

Embodiment 1

Earlier ito glass is carried out photoetching treatment, be cut into needed size, use liquid detergent successively, deionized water, acetone, ethanol, each ultrasonic 15min of isopropyl alcohol removes the organic pollution on ito glass surface; Clean up the back ito glass is carried out suitable processing: oxygen plasma treatment ITO layer, the processing time is 5min, power is 30W; (material is MoO to the evaporation hole injection layer successively₃, thickness is 20nm), hole transmission layer (material is NPB, and thickness is 40nm), (material is TCTA:Ir (ppy) to luminescent layer₃, Ir (ppy)₃Be dopant material, TCTA is material of main part, Ir (ppy)₃The doping mass percent be 10%; The thickness of this luminescent layer is 20nm), electron transfer layer (material is TPBi, and thickness is 60nm); At last on electron transfer layer successively the evaporation electron injecting layer (material is MnO:Cs₂CO₃, MnO is material of main part, Cs₂CO₃Be dopant material, the doping mass percent is 5%; Thickness is 10nm) and cathode layer (material is Ag, and thickness is 100nm).Obtain needed electroluminescent device at last, its structure is: ito glass/MoO₃/ NPB/TCTA:Ir (ppy)₃/ MnO:Cs₂CO₃/ Ag.

Brightness and luminous efficiency graph of a relation between the electroluminescent device that Fig. 2 makes for embodiment 1 and the electroluminescent device of Comparative Examples; The electroluminescent device structure of Comparative Examples is: ito glass/MoO₃/ NPB/TCTA:Ir (ppy)₃/ TPBi/Cs₂CO₃/ Ag; Wherein, curve 1 is the brightness of electroluminescent device of embodiment 1 and the graph of a relation of luminous efficiency; Curve 2 is the brightness of electroluminescent device of Comparative Examples and the graph of a relation of luminous efficiency; 2602), electroluminescent spectrum tester (U.S. photo research company, model: PR650) and screen intensity meter (Beijing Normal University, model: ST-86LA) current-voltage tester (U.S. Keithly company, model:.

From accompanying drawing 2, can see, under different brightness, the brightness of the electron luminescence device that embodiment 1 makes is big than Comparative Examples all, and maximum energy efficiency is 23.8lm/W, and that Comparative Examples only is 16.6lm/W, this explanation is mixed with metal oxide and cesium salt, can effectively improve electronics and inject and transmittability, on the other hand, the nanostructure of material has certain reflection and scattering process to light, therefore, also contributes to improving luminous efficiency.

Embodiment 2

Earlier IZO glass is carried out photoetching treatment, be cut into needed size, use liquid detergent successively, deionized water, acetone, ethanol, each ultrasonic 15min of isopropyl alcohol, the organic pollution of removal IZO glass surface; Clean up the back IZO glass is carried out suitable processing: oxygen plasma treatment IZO layer, the processing time is 5min, power is 50W; (material is WO to the evaporation hole injection layer successively₃Thickness is 10nm), (material is TCTA to hole transmission layer, thickness is 60nm), (material is NPB:Firpic to luminescent layer, NPB is material of main part, Firpic is dopant material, very than being 20%, light emitting layer thickness is 30nm to the doping quality), electron transfer layer (material is Bphen, and thickness is 80nm); At last on electron transfer layer successively the evaporation electron injecting layer (material is WO₃: Cs₂CO₃, WO₃Be material of main part, Cs₂CO₃Be dopant material, the doping mass percent is 1%; Thickness is 5nm) and cathode layer (material is Al, and thickness is 250nm), obtaining needed electroluminescent device at last, its structure is: IZO glass/WO₃/ TCTA/NPB:Firpic/Bphen/WO₃: Cs₂CO₃/ Al.

Embodiment 3

Earlier AZO glass is carried out photoetching treatment, be cut into needed size, use liquid detergent successively, deionized water, acetone, ethanol, each ultrasonic 15min of isopropyl alcohol, the organic pollution of removal AZO glass surface; Clean up the back AZO glass is carried out suitable processing: oxygen plasma treatment AZO layer, the processing time is 15min, power is 10W; (material is V to the evaporation hole injection layer successively₂O₅, thickness is 40nm), hole transmission layer (material is TAPC, and thickness is 60nm), (material is TCTA:Ir (MDQ) to luminescent layer₂(acac), TCTA is material of main part, Ir (MDQ)₂(acac) for dopant material doping quality very than being 1%, light emitting layer thickness is 2nm), electron transfer layer (material is TAZ, and thickness is 40nm); At last on electron transfer layer successively the evaporation electron injecting layer (material is MoO₃: CsF, MoO₃Be material of main part, CsF is dopant material, and the doping mass percent is 5%; Thickness is 10nm) and cathode layer (material is Au, and thickness is 80nm), obtaining needed electroluminescent device at last, its structure is: AZO glass/V₂O₅/ TAPC/TCTA:Ir (MDQ)₂(acac)/TAZ/MoO₃: CsF/Au.

Embodiment 4

Earlier ito glass is carried out photoetching treatment, be cut into needed size, use liquid detergent successively, deionized water, acetone, ethanol, each ultrasonic 15min of isopropyl alcohol removes the organic pollution on ito glass surface; Clean up the back to carrying out suitable processing at the bottom of the ito glass: oxygen plasma treatment ITO layer, the processing time is 15min, power is 10W; (material is MoO to the evaporation hole injection layer successively₃, thickness is 15nm), hole transmission layer (material is NPB, and thickness is 20nm), (material is TAPC:Ir (ppy) to luminescent layer₃, TAPC is material of main part, Ir (ppy)₃Be dopant material, very than being 8%, light emitting layer thickness is 12nm to the doping quality), electron transfer layer (material is TPBi, and thickness is 70nm); At last on electron transfer layer successively the evaporation electron injecting layer (material is MnO:CsN₃, MnO is material of main part, CsN₃Be dopant material, the doping mass percent is 2%; Thickness is 20nm) and cathode layer (material is Pt, and thickness is 180nm), obtaining needed electroluminescent device at last, its structure is: ito glass/MoO₃/ NPB/TAPC:Ir (ppy)₃/ TPBi/MnO:CsN₃/ Pt.

Embodiment 5

Earlier ito glass is carried out photoetching treatment, be cut into needed size, use liquid detergent successively, deionized water, acetone, ethanol, each ultrasonic 15min of isopropyl alcohol removes the organic pollution on ito glass surface; Clean up the back ito glass is carried out suitable processing: oxygen plasma treatment ITO layer, the processing time is 12min, power is 15W; (material is MoO to the evaporation hole injection layer successively₃Thickness is 25nm), (material is TCTA to hole transmission layer, thickness is 30nm), (material is TCTA:Firpic to luminescent layer, TCTA is material of main part, Firpic is dopant material, very than being 15%, light emitting layer thickness is 20nm to the doping quality), electron transfer layer (material is TAZ, and thickness is 50nm); At last on electron transfer layer successively the evaporation electron injecting layer (material is WO₃: Cs₂CO₃, WO₃Be material of main part, Cs₂CO₃Be dopant material, the doping mass percent is 7%; Thickness is 12nm) and cathode layer (material is Ag, and thickness is 200nm), obtaining needed electroluminescent device at last, its structure is: ito glass/MoO₃/ TCTA/TCTA:Firpic/TAZ/WO₃: Cs₂CO₃/ Ag.

Embodiment 6

Earlier ito glass is carried out photoetching treatment, be cut into needed size, use liquid detergent successively, deionized water, acetone, ethanol, each ultrasonic 15min of isopropyl alcohol removes the organic pollution on ito glass surface; Clean up the back ito glass is carried out suitable processing: oxygen plasma treatment ITO layer, the processing time is 5min, power is 30W; (material is MoO to the evaporation hole injection layer successively₃, thickness is 20nm), hole transmission layer (material is NPB, and thickness is 40nm), (material is NPB:Ir (ppy) to luminescent layer₃, Ir (ppy)₃Be dopant material, NPB is material of main part, Ir (ppy)₃The doping mass percent be 15%; The thickness of this luminescent layer is 12nm), electron transfer layer (material is TPBi, and thickness is 60nm); At last on electron transfer layer successively the evaporation electron injecting layer (material is MnO:Cs₂CO₃, MnO is material of main part, Cs₂CO₃Be dopant material, the doping mass percent is 5%; Thickness is 10nm) and cathode layer (material is Ag, and thickness is 100nm).Obtain needed electroluminescent device at last, its structure is: ito glass/MoO₃/ NPB/NPB:Ir (ppy)₃/ MnO:Cs₂CO₃/ Ag.

Embodiment 7

Earlier ito glass is carried out photoetching treatment, be cut into needed size, use liquid detergent successively, deionized water, acetone, ethanol, each ultrasonic 15min of isopropyl alcohol removes the organic pollution on ito glass surface; Clean up the back ito glass is carried out suitable processing: oxygen plasma treatment ITO layer, the processing time is 12min, power is 15W; (material is MoO to the evaporation hole injection layer successively₃Thickness is 25nm), (material is TCTA to hole transmission layer, thickness is 30nm), (material is TAPC:Firpic to luminescent layer, TAPC is material of main part, Firpic is dopant material, very than being 15%, light emitting layer thickness is 20nm to the doping quality), electron transfer layer (material is TAZ, and thickness is 50nm); At last on electron transfer layer successively the evaporation electron injecting layer (material is WO₃: Cs₂CO₃, WO₃Be material of main part, Cs₂CO₃Be dopant material, the doping mass percent is 7%; Thickness is 12nm) and cathode layer (material is Ag, and thickness is 200nm), obtaining needed electroluminescent device at last, its structure is: ito glass/MoO₃/ TCTA/TAPC:Firpic/TAZ/WO₃: Cs₂CO₃/ Ag.

Embodiment 8

Earlier IZO glass is carried out photoetching treatment, be cut into needed size, use liquid detergent successively, deionized water, acetone, ethanol, each ultrasonic 15min of isopropyl alcohol, the organic pollution of removal AZO glass surface; Clean up the back AZO glass is carried out suitable processing: oxygen plasma treatment AZO layer, the processing time is 15min, power is 10W; (material is V to the evaporation hole injection layer successively₂O₅, thickness is 40nm), hole transmission layer (material is TAPC, and thickness is 60nm), (material is TAPC:Ir (MDQ) to luminescent layer₂(acac), TAPC is material of main part, Ir (MDQ)₂(acac) for dopant material doping quality very than being 1%, light emitting layer thickness is 2nm), electron transfer layer (material is TAZ, and thickness is 40nm); At last on electron transfer layer successively the evaporation electron injecting layer (material is MoO₃: CsF, MoO₃Be material of main part, CsF is dopant material, and the doping mass percent is 5%; Thickness is 10nm) and cathode layer (material is Au, and thickness is 80nm), obtaining needed electroluminescent device at last, its structure is: IZO glass/V₂O₅/ TAPC/TAPC:Ir (MDQ)₂(acac)/TAZ/MoO₃: CsF/Au.

Embodiment 9

Earlier ito glass is carried out photoetching treatment, be cut into needed size, use liquid detergent successively, deionized water, acetone, ethanol, each ultrasonic 15min of isopropyl alcohol, the organic pollution of removal AZO glass surface; Clean up the back AZO glass is carried out suitable processing: oxygen plasma treatment AZO layer, the processing time is 15min, power is 10W; (material is V to the evaporation hole injection layer successively₂O₅, thickness is 40nm), hole transmission layer (material is TAPC, and thickness is 60nm), (material is NPB:Ir (MDQ) to luminescent layer₂(acac), NPB is material of main part, Ir (MDQ)₂(acac) for dopant material doping quality very than being 1%, light emitting layer thickness is 2nm), electron transfer layer (material is TAZ, and thickness is 40nm); At last on electron transfer layer successively the evaporation electron injecting layer (material is MoO₃: CsF, MoO₃Be material of main part, CsF is dopant material, and the doping mass percent is 5%; Thickness is 10nm) and cathode layer (material is Au, and thickness is 80nm), obtaining needed electroluminescent device at last, its structure is: ito glass/V₂O₅/ TAPC/NPB:Ir (MDQ)₂(acac)/TAZ/MoO₃: CsF/Au.

Should be understood that above-mentioned statement at preferred embodiment of the present invention is comparatively detailed, can not therefore think the restriction to scope of patent protection of the present invention, scope of patent protection of the present invention should be as the criterion with claims.

Claims (9)

1. an electroluminescent device is characterized in that, comprises the anode conducting substrate of glass, hole injection layer, hole transmission layer, luminescent layer, electron transfer layer, electron injecting layer and the cathode layer that stack gradually; Wherein, the material of described electron injecting layer is the doped metallic oxide cesium salt, and the doping mass percent of cesium salt is 1～10%; The thickness of described electron injecting layer is 5～20nm.

2. electroluminescent device according to claim 1 is characterized in that, described anode conducting glass is selected from indium tin oxide glass, mix the zinc oxide glass of aluminium or mix the zinc oxide glass of indium.

3. electroluminescent device according to claim 1 is characterized in that, the material of described hole injection layer is selected from molybdenum trioxide, tungstic acid or vanadic oxide; The thickness of described hole injection layer is 10-40nm.

4. electroluminescent device according to claim 1, it is characterized in that, the material of described hole transmission layer is selected from 1,1-two [4-[N, N '-two (p-tolyl) amino] phenyl] cyclohexane, 4,4 ', 4 " three (carbazole-9-yl) triphenylamine, N; N '-(1-naphthyl)-N, N '-diphenyl-4,4 '-benzidine; The thickness of described hole transmission layer is 20-60nm.

5. electroluminescent device according to claim 1 is characterized in that, to be dopant material be doped to the composite material of forming in the material of main part according to the ratio of mass percent 1～20% to the material of described luminescent layer; Wherein, dopant material is selected from two (4,6-difluorophenyl pyridine-N, C²) the pyridine formyl closes iridium, two (2-methyl-diphenyl [f, h] quinoxaline) (acetylacetone,2,4-pentanedione) and close iridium or three (2-phenylpyridine) and close iridium; Material of main part is selected from 1,1-two [4-[N, N '-two (p-tolyl) amino] phenyl] cyclohexane, 4,4 ', 4 " three (carbazole-9-yl) triphenylamine, N, N '-(1-naphthyl)-N, N '-diphenyl-4,4 '-benzidines; The thickness of described luminescent layer is 2-30nm.

6. electroluminescent device according to claim 1 is characterized in that, the material of described electron transfer layer is selected from 4,7-diphenyl-1,10-phenanthroline, 1,2,4-triazole derivative or N-aryl benzimidazole; The thickness of described electron transfer layer is 40-80nm.

7. electroluminescent device according to claim 1 is characterized in that, described cesium salt is selected from cesium carbonate, cesium fluoride or nitrine caesium; Described metal oxide is selected from manganese oxide, tungsten oxide or molybdenum oxide.

8. electroluminescent device according to claim 1 is characterized in that, the material of described cathode layer is selected from silver, aluminium, platinum or gold; The thickness of described cathode layer is 80～250nm.

9. the preparation method of the described electroluminescent device of claim 1 is characterized in that, comprises the steps;

S1, the anode conducting substrate of glass is carried out photoetching treatment, use liquid detergent, deionized water, acetone, ethanol, each ultrasonic cleaning 15min of isopropyl alcohol subsequently successively, remove organic pollution;

S2, will clean up back antianode electro-conductive glass suprabasil anode layer and carry out oxygen plasma treatment, the processing time is 5-15min, and power is 10-50W;

S3, employing evaporation process stack gradually evaporation hole injection layer, hole transmission layer, luminescent layer, electron transfer layer, electron injecting layer and cathode layer on the anode layer surface of anode conducting substrate of glass; Wherein, the material of described electron injecting layer is the doped metallic oxide cesium salt, and the doping mass percent of cesium salt is 1～10%; The thickness of described electron injecting layer is 5～20nm;

After above-mentioned processing step is finished, make electroluminescent device.

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