CN-116854677-B - Capping layer material, preparation method thereof, organic electroluminescent device and display device

Abstract

The invention relates to a benzocarbazole capping layer material, a preparation method thereof, an organic electroluminescent device and a display device, and belongs to the technical field of organic luminescent materials. The general structural formula of the capping layer material is shown in the general formula 1: Since the organic EL element of the present invention uses the material of the cap layer, which has a high refractive index, good film stability, and excellent durability, the light extraction efficiency is greatly improved compared with the known organic EL element, and the technical effects of high efficiency and long life are achieved.

Inventors

• MA XIAOYU
• JIN CHENGSHOU
• HAN RUIFENG
• REN WEIHUA
• TANG ZHIJIE

Assignees

• 吉林奥来德光电材料股份有限公司

Dates

Publication Date

20260508

Application Date

20230605

Claims (3)

1. 1. The capping layer material is characterized by having a structural general formula of formula 1: ; the general formula 1 is one of the following structural formulas: ; 。
2. 2. An organic electroluminescent device comprising an anode, a cathode and at least one organic layer disposed between the anode and the cathode, wherein the cathode is provided with a capping layer on a side remote from the organic layer, and wherein the capping layer comprises the capping layer material of claim 1.
3. 3. A display device comprising a substrate, characterized by further comprising the organic electroluminescent device of claim 2 disposed on the substrate.

Description

Capping layer material, preparation method thereof, organic electroluminescent device and display device Technical Field The invention relates to the technical field of organic luminescent materials, in particular to a benzocarbazole capping layer material, a preparation method thereof, an organic electroluminescent device and a display device. Background Organic electroluminescent (Organic Light Emission Diodes, OLED) devices can be used in place of liquid crystal displays and fluorescent lamp illumination to make display devices and illumination products. Specifically, the OLED device can be widely applied to the fields of smart phones, tablet computers, televisions and the like. The conventional OLED device generally comprises an anode, a cathode, an organic layer positioned between the anode and the cathode, and a cap layer (CAPPING LAYER, CPL) positioned outside the cathode, wherein the organic layer comprises a light-emitting layer and other functional structures. Among them, the cap layer can play a role in improving the light extraction efficiency and further improving the light emission efficiency of the device, and until now, various roles have been further subdivided for practical use of an organic EL (electroluminescence) element, and an anode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a cathode are provided in order of function on a substrate. In the organic electroluminescent device, high efficiency and durability have been achieved by the light emitting element of the bottom light emitting structure emitting light from the bottom. As the refractive index adjusting coating layer, it is known to use aluminum (8-hydroxyquinoline) (hereinafter abbreviated as Alq 3). Alq3 is often used as a green light emitting material or an electron transporting material, but has weak absorption around 450nm used for a blue light emitting element. Therefore, in the case of a blue light emitting element, there is a problem that color purity is lowered and light extraction efficiency is lowered together. The existing CPL material improves the light extraction efficiency to a certain extent. However, the refractive index of the existing CPL material is generally below 1.9, and the existing CPL material cannot meet the requirement of high refractive index, and has low luminous efficiency. In order to improve the characteristics of the organic EL element, in particular, to greatly improve the light extraction efficiency, it is necessary to develop a material having a high refractive index to improve the light extraction efficiency and solve the problem of the light emission efficiency. As the cap layer material, a material having a high refractive index and excellent film stability or durability is demanded. Disclosure of Invention The invention aims to provide a capping layer material, a preparation method thereof, an organic electroluminescent device and a display device, so as to solve the problems in the prior art. In order to achieve the above purpose, the present invention provides the following technical solutions: a capping layer material having a structural formula of formula 1: wherein X 1、X2、X3 is the same as or different from each other, and X 1、X2、X3 is independently selected from O or S; L 1、L2、L3 are identical or different from each other and are independently any one of a bond, a substituted or unsubstituted C3-C60 cycloalkyl group, a substituted or unsubstituted 3-to 30-membered heterocycloalkyl group, a substituted or unsubstituted C6-C60 arylene group, a substituted or unsubstituted 3-to 30-membered heteroarylene group, the heteroatoms of which are selected from oxygen, nitrogen or sulfur. As a further embodiment of the present invention, L 1、L2、L3 are the same or different from each other and are independently any one of a bond, a substituted or unsubstituted C6-C30 arylene group, a substituted or unsubstituted 3-to 15-membered heteroarylene group, a heteroatom of which is selected from oxygen, nitrogen, or sulfur. As a further aspect of the present invention, the L 1、L2、L3 are the same or different from each other, and are independently a bond or one of the following structural formulas: wherein, is the connection point. As a still further technical scheme of the invention, the capping layer material is one of the following structural formulas CP1-CP 30: a method of preparing a capping layer material comprising the steps of: Under the protection of nitrogen, dissolving a raw material A and a raw material B in DMF solution, adding cesium carbonate, heating and carrying out reflux reaction to obtain an intermediate 1; Under the protection of nitrogen, dissolving the intermediate 1 and a raw material C in a mixed solution of toluene, ethanol and water, adding potassium carbonate and a palladium catalyst, uniformly stirring, heating and carrying out reflux reaction to obtain the intermediate 2; Under the prote