CN1728905A - An organic thin film electroluminescent device - Google Patents

Abstract

The Electroluminescent device is composed of following layers and parts prepared on clear electrode: cavity transport layer, organic luminous layer, inorganic electron transport layer, electronic potentiometric compensator layer and back electrode. Inorganic electron transport layer is prepared from n type ZnS or n type ZnO with thickness 1nm-10nm. Inorganic electron transport layer is also prepared from other n type wide forbidden band inorganic materials: n type CoO, n type GaN, n type BaO, n type MgO or n type AIN. The invention raises luminescence brightness, efficiency and service life since mutual diffusion between luminous layer and electrode in electroluminescent device and inadequate balance between cavities and electrons are improved in the disclosed structure.

Description

An organic thin film electroluminescent device

technical field

The invention relates to an organic thin film electroluminescent device, which is mainly used for producing an organic thin film electroluminescent device with high brightness, efficiency and long life.

Background technique

Since Deng Qingyun C.W.Tang of Kodak Company of the United States reported organic electroluminescence in 1987, there has been an upsurge in the research of organic thin film light-emitting diodes all over the world. Organic thin-film light-emitting diodes have unique advantages such as active light emission, fast response, full solidification, easy colorization, and low driving voltage. They are very potential flat panel displays that will replace the current liquid crystal displays that dominate the market. It is precisely because of its background in the field of flat panel display that many companies, universities and research institutes have invested a lot of manpower and material resources in organic electroluminescent display. There are about 80 large companies in the world participating in the organic electroluminescent industry. In the competition of globalization, for example, Japan's Pioneer Company purchased a patent from Kodak a few years ago and prepared a matrix screen, which was launched in 1998 and launched a color matrix screen at the end of the same year. Philips also wants to seize the market, and has prepared an ideal organic electroluminescent device by using polymers. At the beginning of 2000, Motorola had already used OLED display devices for mobile phones, and at the end of the year, LG also decided to participate in this project, and in 2001, 12 million OLED displays were used in mobile phones. China's largest picture tube manufacturer - Rainbow Company has invested more than 30 million yuan in Tsinghua University to develop OLED. China Aerospace Machinery and Electronics Corporation Shanghai Pudong Development Center and Shanghai Vacuum Electronics Group Corporation are also looking for investment partners in scientific research departments to jointly research Developed OLEDs. China's leading scientific research institutions in OLED include Shanghai University, Tsinghua University, City University of Hong Kong, Jilin University, Changchun Institute of Optics, Mechanics and Physics, Beijing Jiaotong University, Fudan University and so on. In the world, there are countless research groups engaged in research in this field. Huge investment and unremitting efforts have yielded fruitful results. However, organic electroluminescent devices with high brightness, long life and high efficiency are always dreamed by people.

Although the development of organic electroluminescent devices is very rapid, the scale of development is also unprecedented. However, in order to obtain high-brightness, high-efficiency and long-life organic electroluminescent devices, some problems in organic electroluminescence have not been well resolved, such as the limitations of current hole and electron transport layer materials and preparation processes. , with the structure of ordinary organic electroluminescent devices: ITO/hole transport layer/organic light-emitting layer/back electrode, there are some problems as follows: mutual diffusion between the light-emitting layer and the electrode, not enough hole and electron mobility , and the injected holes and electrons are not balanced enough. These problems limit the further improvement of organic electroluminescent devices and become an important bottleneck in the development of organic electroluminescent devices, making it impossible to prepare organic light-emitting devices with excellent performance.

Contents of the invention

The technical problem to be solved by the present invention is to improve the structure of the organic thin film electroluminescent device and the material of the electron transport layer, so as to effectively improve the brightness, efficiency and service life of the organic thin film electroluminescent device.

Technical scheme of the present invention:

The present invention sequentially prepares a hole-transporting layer, an organic light-emitting layer, an electron-transporting layer, an electron potential compensation layer and a back electrode on a transparent electrode to sequentially prepare an organic electroluminescent device with a film structure, and is characterized in that: the organic light-emitting layer and the electron An electron transport layer is added between the potential compensation layers, and the electron transport layer adopts a wide band gap inorganic material.

Beneficial effects of the invention: the structure of adding an inorganic electron transport layer between the organic light-emitting layer and the electron potential compensation layer can greatly improve the mutual diffusion between the light-emitting layer and the electrode of the organic electroluminescent device, and the injected hole and electron Insufficient balance, etc., so that the luminous brightness, efficiency and life of the organic electroluminescent device are improved.

Description of drawings

Fig. 1 is a schematic structural diagram of an organic thin film electroluminescence device.

In the figure: a transparent electrode 1 , a hole transport layer 2 , an organic light-emitting layer 3 , an inorganic electron transport layer 6 , an electron potential compensation layer 4 and a back electrode 5 .

Detailed ways

The present invention will be further described by taking the accompanying drawings as embodiments. The novel electron transport layer organic thin film electroluminescent device is composed of a hole transport layer 2, an organic light-emitting layer 3, an inorganic electron transport layer 6, an electron potential compensation layer 4 and a back electrode 5 sequentially prepared on a transparent electrode 1.

The electron potential compensation layer 4 is made of lithium fluoride LiF, located between the electron transport layer 6 and the back electrode 5, and the thickness of the electron potential compensation layer 4 is 0.2nm-0.6nm. When the energy of the back electrode 5 and the electron transport layer 6 are matched, the electron potential compensation layer 4 is canceled.

The inorganic electron transport layer 6 is made of n-type zinc sulfide ZnS, which is located between the light-emitting layer 3 and the electron potential compensation layer 4. The inorganic electron transport layer 6 can also be made of other inorganic n-type wide bandgap semiconductor materials. The thickness of the inorganic electron transport layer 6 is 1 nm to 10 nm. Inorganic n-type wide bandgap semiconductor materials: n-type zinc sulfide ZnS, n-type zinc oxide ZnO, n-type cobalt oxide CoO, n-type gallium nitride GaN, n-type barium oxide BaO, n-type magnesium oxide MgO and n-type nitride Aluminum AlN.

The organic light-emitting layer 3 is made of organic material Alq ₃ (8-hydroxyquinoline aluminum). The thickness of the organic light-emitting layer 3 is 20nm-60nm. The organic light-emitting layer 3 can also use an organic material: DCJTB (4-(dinitrile methyl)-2-butyl-6-(1,1,7,7-tetramethyljuronesidine-9-vinyl) -4H-pyran), TBP (tetra-tert-butylperylene), AND (9,10-di-β-naphthylene anthracene), BALQ (di(2-methyl-8-hydroxyquinoline) -(4-biphenol)aluminum), DCJTI (4-(dinitrile methylenyl)-2-isopropyl-6-(1,1,7,7-tetramethyljulonedine-9-ethylene base)-4H-pyran), DCJTB(4-(dinitrile methyl)-2-butyl-6-(1,1,7,7-tetramethyljuronesidine-9-vinyl)- 4H-pyran), C545T(10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H-(1 )-benzopyran(6,7-8-i,j)quinazin-11-one) and DMQA (dimethylquinacridone). The organic light-emitting layer 3 can also use a polymer: PPV (poly-p-phenylene vinylene and its derivatives).

The hole transport layer 2 uses an organic material NPB (N,N'-(1-naphthyl)-N,N'-diphenyl-4,4'-biphenylenediamine). The hole transport layer 2 has a thickness of 20 nm to 60 nm. The hole transport layer 2 can also adopt CBP (4,4'-two (carbazolyl-9) biphenyl), CuPc (phthalo-bronze) and TPD (N, N'-two (3-methylphenyl)- N,N'-diphenyl-4,4'-biphenylenediamine). The hole transport layer 2 can also use the polymer material PVK (polyvinyl carbazole).

The transparent electrode 1 is made of indium tin oxide ITO glass. The transparent electrode 1 can also use indium zinc oxide InZnO.

Aluminum Al is used for the back electrode 5 . The back electrode 5 can also use magnesium-silver alloy MgAg. The organic thin film electroluminescent device improves the interdiffusion between the light-emitting layer and the electrode of the organic electroluminescent device, the imbalance of injected holes and electrons, etc., thereby effectively improving the brightness, efficiency and life of the organic thin film electroluminescent device.

Claims (3)

1. an electroluminescent device of organic thin film constitutes by prepare hole transmission layer, organic luminous layer, electron transfer layer, electron potential layer of compensation and back electrode successively on the transparency electrode substrate; It is characterized in that: between organic luminous layer (3) and electron potential layer of compensation (4), add inorganic electronic transport layer (6) by n type ZnS or n type ZnO preparation.

2. a kind of electroluminescent device of organic thin film according to claim 1 is characterized in that: electron transfer layer (6) can also adopt other n molded breadth forbidden band inorganic material: n type CoO, n type GaN, n type BaO, n type MgO or n type AlN.

3. novel electron transport layer electroluminescent device of organic thin film according to claim 1 is characterized in that: the thickness 1nm-10nm of inorganic electronic transport layer (6).

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