Thermal activation delayed fluorescent material and application of thermal activation delayed fluorescent material to organic light emitting diodes

Abstract

The invention provides a thermal activation delayed fluorescent material and application of the thermal activation delayed fluorescent material to organic light emitting diodes. The chemical structureof the thermal activation delayed fluorescent material is shown as a formula (1). A group R in the formula (1) is a chemical group, and triphenylamine derivatives and carbazole derivatives are linkedwith one another to form the chemical group; the R is selectively a type of the certain carbazole derivatives, and the numbers of annular carbon atoms of the certain carbazole derivatives are 18. Thethermal activation delayed fluorescent material and the application have the advantages that donor groups of organic light emitting materials are modified, accordingly, the current carrier transportperformance of the donor groups can be greatly improved, and the organic light emitting materials are good in device performance when applied to blue light, deep blue light or white light; the thermalactivation delayed fluorescent material not only can be used as blue light dye, but also can be used as a host material for yellow light or green light dye; the problem of efficiency roll-off under the condition of high brightness can be solved when the thermal activation delayed fluorescent material is applied to the organic light emitting diodes with single light emitting layers, the structuresof white organic light emitting diode devices can be simplified, and the industrial production cost can be reduced.

Description

technical field [0001] The invention belongs to the field of organic synthesis and semiconductor devices, in particular to a thermally activated delayed fluorescent material and its application in organic light emitting diodes. Background technique [0002] Organic light-emitting diodes are now widely used in screen displays and lighting. Red / green / blue primary color luminescent materials are the key to improving device performance, especially blue light materials, which are used not only as luminescent dyes for white light devices but also as host materials for long-wavelength yellow / green / red light dyes. Single-layer white light devices have great market prospects due to their simplicity and low cost. Usually, a single-layer white light requires a blue fluorescent host, which can be used not only as a light-emitting material but also as another yellow-light guest material or two green / red-light materials as hosts for dyes. However, the research on the efficiency and life...

AI Technical Summary

Problems solved by technology

However, the research on the efficiency and lifetime of blue light materials is not very mature. Due to the serious quenching effect and triplet annihilation effect, the research on blue light materials has become a difficult and important point.

[0003] At present, the theoretical external quantum efficiency (EQE) of traditional blue fluorescent materials is less than 5%, and using traditional fluorescent materials as the light-emitting host material of single-layer white light devices, the efficiency of the device and the efficiency roll-off at high brightness are all in a very low range. high level

[0004] (1) The highest occupied molecular orbital energy level (HOMO) of the material does not match, so it is not suitable as the main material for white light devices;

[0005] (2) Due to the stronger acceptor unit in TADF, TADF materials usually have better electron transport properties, but their high ionization potential results in deeper highest occupied molecular orbital energy levels;

[0006] (3) In order to obtain blue light, it is necessary to reduce the conjugation between the material donor and the acceptor, resulting in an imbalance of carrier mobility, which leads to the quenching effect of excitons in the device

[0007] Therefore, although the efficiency of conventional single-layer hybrid white organic light-emitting diodes has been developed to a high level, the efficiency roll-off at high brightness is usually large, which is not conducive to the application in the field of white lighting.

Moreover, in blue light TADF materials, in order to make the light color more blue, a stronger donor group is usually used, which not only reduces the plane conjugation, but also causes the imbalance of transmission.

Therefore, when the blue TADF material is used as the host material of a single-layer white OLED, the efficiency roll-off is obvious when the current increases.

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