CN-116261345-B - Organic electroluminescent device

CN116261345BCN 116261345 BCN116261345 BCN 116261345BCN-116261345-B

Abstract

The application relates to the technical field of organic electroluminescence, and discloses an organic electroluminescent device which sequentially comprises an anode layer, a hole injection layer, a hole transmission layer, an electron blocking layer, a luminescent layer, a hole blocking layer, an electron transmission layer, an electron injection layer and a metal cathode layer from bottom to top, wherein the luminescent layer comprises a main material, a sensitizer and blue fluorescent dye, the sensitizer is doped in the main material in a gradient doping concentration mode, the doping concentration of the sensitizer is reduced in a gradient mode from the electron blocking layer to the hole blocking layer, and the blue fluorescent dye is doped in the main material in a fixed doping concentration mode. The organic electroluminescent device can achieve the effects of improving the efficiency roll-off and prolonging the service life by optimizing the structure of the device and a material collocation system.

Inventors

LIANG JIE
SONG XIAOXIAN
WANG ZHIHENG
BI HAI
WANG YUE

Assignees

季华实验室

Dates

Publication Date: 20260505
Application Date: 20230303

Claims (6)

1. The organic electroluminescent device is characterized by comprising an anode layer, a hole injection layer, a hole transport layer, an electron blocking layer, a light emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer and a metal cathode layer from bottom to top in sequence; the light-emitting layer comprises a main body material, a sensitizer and a blue fluorescent dye; The sensitizer is doped in the main material in a gradient doping concentration mode, the doping concentration range of the sensitizer is between 5 and 50 wt percent, and the doping concentration of the sensitizer is reduced in a gradient manner from the electron blocking layer to the hole blocking layer; The blue fluorescent dye is doped in the main material in a mode of fixed doping concentration, and the doping concentration range of the blue fluorescent dye is 0.1-10 wt%; the sensitizer is a phosphorescence sensitizer or a thermal activation delay fluorescence sensitizer; The host material is a material having an electron transport property or a hole transport property; The phosphorescence sensitizer is one of iridium complex and platinum complex; the thermal activation delay fluorescence sensitizer is one of a donor-acceptor type TADF material and a multi-resonance type TADF material; The triplet energy level of the host material is greater than or equal to the triplet energy levels of the sensitizer and the blue fluorescent dye; The triplet energy level of the sensitizer is greater than or equal to the triplet energy level of the blue fluorescent dye.
2. The organic electroluminescent device of claim 1, wherein the hole injection layer has a thickness of 5-20 nm a, the hole transport layer has a thickness of 20-100 a nm a, the electron blocking layer has a thickness of 5-10 a nm a, the light emitting layer has a thickness of 20-40 a nm a, the hole blocking layer has a thickness of 5-10 a nm a, the electron transport layer has a thickness of 30-100 a nm a, and the electron injection layer has a thickness of 0.5-10 a nm a.
3. The organic electroluminescent device of claim 1, wherein the anode layer has a thickness of 60-120 nm and the metal cathode layer has a thickness of 200-300 nm.
4. The organic electroluminescent device of claim 1, wherein the host material has a HOMO level greater than or equal to the HOMO level of the sensitizer and the blue fluorescent dye, and wherein the host material has a LUMO level greater than or equal to the LUMO level of the sensitizer and the blue fluorescent dye.
5. The organic electroluminescent device according to claim 4, wherein the HOMO level of the sensitizer is greater than or equal to the HOMO level of the blue fluorescent dye, and the LUMO level of the sensitizer is greater than or equal to the LUMO level of the blue fluorescent dye.
6. The organic electroluminescent device of claim 1, wherein the sensitizer is an organic phosphorescent material Ir (cb) 3 ; the blue fluorescent dye is DABNA; the material with electron transport property is DPEPO, and the material with hole transport property is mCBP; The hole injection layer is composed of HATCN; The hole transport layer is composed of TAPC; The electron blocking layer is composed of mCP; the hole blocking layer is composed of TSPO 1; the electron transport layer consists of TmPyPB; The electron injection layer is composed of an alkali metal; the anode layer is composed of ITO or indium gallium zinc oxide; the metal cathode layer is composed of aluminum or magnesium aluminum alloy.

Description

Organic electroluminescent device Technical Field The application relates to the technical field of organic electroluminescence, in particular to an organic electroluminescent device. Background In recent years, organic light-emitting diodes (OLEDs) have taken up a considerable market share in the current full-color flat panel display field, and have also shown a wide application prospect in the future energy-saving and environment-friendly solid state lighting field, attracting more and more attention of academic and commercial enterprises, and rapidly developing. The material is a key factor for determining the performance of the device, and has very important significance in researching and exploring the organic electroluminescent material meeting the market demands. Over the last decades, the luminescent materials of OLEDs have completed a perfect transition from fluorescent, phosphorescent to Thermally Activated Delayed Fluorescent (TADF) materials, resulting in a significant increase in the selectivity of the OLED material market. At present, through innovation of a molecular structure of a material and continuous optimization of a device process, the efficiency and the service life of an OLED device based on blue light, green light and red light materials are continuously improved and prolonged, a large breakthrough is realized in terms of color purity, and some OLED devices have reached the requirement of commercialization. However, current OLED devices based on blue materials often suffer from one or more drawbacks such as large efficiency roll-off, insufficient operating life, poor color purity, and the like. For blue light materials, the device structure design and the material system collocation will have significant influence on the performance such as efficiency, service life and color purity. On one hand, the exciton service life of phosphorescence and TADF materials is relatively longer (microsecond to millisecond scale), annihilation of excitons, polarons and the like is easy to occur in the device under high brightness, non-radiative energy loss and aging and attenuation of organic materials are generated, so that the device efficiency roll-off is serious, the service life is greatly shortened, the development of the blue OLED device market is severely restricted, on the other hand, in order to improve the device efficiency and service life, a plurality of functional layers are generally adopted for constructing the device to realize high-efficiency luminescence, however, the energy level matching problem of the multifunctional layers can bring the problems of unbalanced carrier transmission of the luminescent layer and narrowing of the composite area of the luminescent layer, the exciton accumulation of the interface of the luminescent layer and the transmission layer is further induced, the exciton quenching and the aging problem of an organic layer body are further induced, the luminous efficiency and the service life stability of the device are influenced, and the efficiency and the service life of the OLED device cannot meet the industrialization requirements. Accordingly, the prior art is still in need of improvement and development. Disclosure of Invention In view of the above-mentioned shortcomings of the prior art, the present application aims to provide an organic electroluminescent device, which aims to solve the problems of low efficiency and short lifetime of the existing blue OLED device. The technical scheme of the application is as follows: an organic electroluminescent device, wherein the organic electroluminescent device comprises an anode layer, a hole injection layer, a hole transport layer, an electron blocking layer, a luminescent layer, a hole blocking layer, an electron transport layer, an electron injection layer and a metal cathode layer from bottom to top in sequence; the light-emitting layer comprises a main body material, a sensitizer and a blue fluorescent dye; The sensitizer is doped in the main material in a gradient doping concentration mode, the doping concentration range of the sensitizer is between 5 and 50 wt percent, and the doping concentration of the sensitizer is reduced in a gradient manner from the electron blocking layer to the hole blocking layer; the blue fluorescent dye is doped in the main material in a mode of fixed doping concentration, and the doping concentration range of the blue fluorescent dye is 0.1-10 wt%. The sensitizer is a phosphorescence sensitizer or a thermal activation delay fluorescence sensitizer. The organic electroluminescent device can achieve the effects of improving the efficiency roll-off and prolonging the service life by optimizing the structure of the device and a material collocation system. When the sensitizer is a phosphorescent sensitizer, the material matching system of the light emitting layer is a host material (host) +phosphorescent sensitizer (P) +blue fluorescent dye (F) =psf system. When the sensitizer is