An Organic Electroluminescence Device Based on Exciplex and Exciplex System

Abstract

The invention relates to an organic electroluminescent device based on exciplex and excimate system. Wherein the host material of the light-emitting layer includes the first, second and third organic compounds. The mixture or layered interface formed by the first and second organic substances generates exciplexes under optical or electrical excitation. The third organic compound is doped in the mixture formed by the first and the second organic compound or in a layer of the stack interface, and the third organic compound forms an excimer association; the singlet energy level of the exciplex is higher than that of the third The singlet energy level of an organic compound, the triplet energy level is higher than the triplet energy level of a third organic compound. The singlet energy level of the excimate is higher than the singlet energy level of the guest material, and the triplet energy level is higher than the triplet energy level of the guest material; and the first organic compound and the second organic compound have different carrying currents Sub-transport characteristics, the guest doping material is a fluorescent compound. The device of the invention has the characteristics of high efficiency and long life.

Description

technical field [0001] The present invention relates to the field of semiconductor technology, in particular to a high-efficiency, long-life organic electroluminescence device based on an exciplex and an excimer system. Background technique [0002] Organic electroluminescent diodes (OLEDs) have been actively researched and developed. The simplest basic structure of an organic electroluminescent device consists of an emissive layer, sandwiched between opposing cathode and anode. Organic electroluminescent devices are considered to be the next generation of flat panel display materials and have attracted widespread attention due to their ultra-thin and ultra-lightweight, fast response to input signals, and low-voltage DC driving. [0003] It is generally believed that organic electroluminescence devices have the following light-emitting mechanism: when a voltage is applied between electrodes sandwiching the light-emitting layer, electrons injected from the anode and holes in...

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Problems solved by technology

[0006] Although theoretically TADF materials can achieve 100% exciton utilization, there are actually the following problems: (1) The T1 and S1 states of the designed molecules have strong CT characteristics, and the very small S1-T1 state energy gap, although it can A high T1→S1 state exciton conversion rate is achieved through the TADF process, but at the same time it leads to a low S1 state radiative transition rate. Therefore, it is difficult to achieve both (or simultaneously) high exciton utilization efficiency and high fluorescence radiation efficiency;

[0007] (2) Due to the current use of TADF materials with D-A, D-A-D or A-D-A structures, due to their greater molecular flexibility, the configuration of molecules in the ground state and excited state changes greatly, and the half-maximum width (FWHM) of the spectrum of the material is too large. Large, resulting in a reduction in the color purity of the material;

[0008] (3) Even if doped devices have been used to alleviate the T-exciton concentration quenching effect, the efficiency of most TADF materials has a serious roll-off at high current densities

[0009] (4) In the traditional host-guest collocation method, due to the different electron and hole transport rates of the host material, the carrier recombination rate is reduced, resulting in a decrease in device efficiency; at the same time, the carrier complex area is close to the side of the host material, The carrier recombination area is too concentrated, resulting in too concentrated triplet base density, resulting in obvious carrier quenching, and reduced device efficiency and lifetime

However, there are still insufficient carrier recombination and low device efficiency and lifetime.

At the same time, the half-peak width of the device spectrum is large, which is not conducive to the improvement of the color purity of the device

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