阅读说明：本技术 一种可溶液加工的热激活延迟荧光材料及其制法和应用 (Solution-processable thermally-activated delayed fluorescent material and preparation method and application thereof ) 是由 蒋伟 夏明辉 于 2020-05-20 设计创作，主要内容包括：本发明公开了一种可溶液加工的热激活延迟荧光材料及其制法和应用,该可溶液加工的热激活延迟荧光材料包含一种分子结构,该分子结构由两部分组成,一部分是具有热激活延迟荧光性质的核,另一部分是具有高三线态能级的结构,其中,R<Sub>1</Sub>、R<Sub>2</Sub>中最多有一个是氢,其余均为通过苯环和氧连接,并且氧连接具有高三线态能级的结构。该新型材料具有较大优势,外围支链的空间位阻效应能有效降低三线态激子的浓度淬灭,提高发光器件的性能；苯环的引入能够有效的增强材料溶解性和成膜性。这类可溶液加工的热激活延迟荧光材料具有较大的分子量,良好的成膜性能,适用于湿法制备有机电致发光器件。且随着外围支链的增多,器件性能得到较大的提高。<Image he="697" wi="700" file="DDA0002500270090000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>(The invention discloses a solution-processable thermal activation delayed fluorescence material and a preparation method and application thereof 1 、R 2 At most one of them is hydrogen, the others are all structures linked through a benzene ring and oxygen, and the oxygen linkage has a high triplet level. The novel material has great advantages, and the steric hindrance of peripheral branched chainsThe effect can effectively reduce the concentration quenching of triplet excitons and improve the performance of the luminescent device; the introduction of the benzene ring can effectively enhance the solubility and the film-forming property of the material. The thermally activated delayed fluorescence material capable of being processed by solution has larger molecular weight and good film-forming property, and is suitable for preparing organic electroluminescent devices by a wet method. And with the increase of peripheral branched chains, the performance of the device is greatly improved.)

1. A solution processable thermally activated delayed fluorescence material comprising a molecular structure consisting of two parts, one part being a core with thermally activated delayed fluorescence properties and the other part being a structure with a high triplet level, as follows:

wherein R is₁、R₂At most one of them is hydrogen, the others areAre all structures that are linked through a benzene ring and oxygen, and the oxygen linkage has a high triplet energy level.

2. The solution processable thermally activated delayed fluorescence material of claim 1, wherein the core structure having thermally activated delayed fluorescence properties is as follows:

3. the solution processable thermally activated delayed fluorescence material of claim 1, wherein the structure having the high triplet energy level is any one of the following structures:

4. a solution processable thermally activated delayed fluorescence material as claimed in claim 1, wherein the molecular structure is selected from the following chemical structural formulas:

5. the method for preparing a thermally activated delayed fluorescence material capable of being solution processed according to claim 1, wherein the method comprises the steps of preparing a peripheral branch, connecting the peripheral branch with a benzene ring through nucleophilic substitution, and connecting the peripheral branch with a core having a thermally activated delayed fluorescence property through a carbon-nitrogen coupling reaction to obtain the dendritic thermally activated delayed fluorescence material.

6. The method for preparing a solution processable thermally activated delayed fluorescence material as claimed in claim 5, comprising the steps of:

reacting 3, 6-dihydroxy-9-hydrogen-carbazole, cesium carbonate, 9- (4-iodophenyl) -9H-carbazole and N, N-dimethylformamide at 90-110 ℃ for 3-5H under the protection of nitrogen, collecting a reaction product, and purifying by column chromatography to obtain 3, 6-bis (4- (9H-carbazole-9-yl) phenoxy) -9H-carbazole; adding 3, 6-bis (4- (9H-carbazole-9-yl) phenoxy) -9H-carbazole and sodium hydride into dried tetrahydrofuran for reaction, then adding 2,3,4,5, 6-pentafluorobenzonitrile, stirring for reaction, adding water for precipitation and quenching after the reaction is finished, extracting by dichloromethane, and purifying by column chromatography;

or the like, or, alternatively,

reacting 3-hydroxy carbazole, cesium carbonate, 9- (4-iodophenyl) -9H-carbazole and N, N-dimethylformamide at 90-110 ℃ for 3-5H under the protection of nitrogen, collecting reaction products, and purifying by column chromatography; adding the purified product obtained in the previous step and sodium hydride into dried tetrahydrofuran for reaction, and then adding 2,3,4,5, 6-pentafluorobenzonitrile for reaction; after the reaction is finished, water is added for precipitation and quenching, dichloromethane is used for extraction, and column chromatography is used for purification;

or the like, or, alternatively,

reacting 3, 6-dihydroxy-9-hydrogen-carbazole, cesium carbonate, 4-iodo-N, N-diphenylaniline and N, N-dimethylformamide at 90-110 ℃ for 3-5h under the protection of nitrogen, collecting a reaction product, and purifying by column chromatography; adding the purified product obtained in the previous step and sodium hydride into dried tetrahydrofuran for reaction, and then adding 2,3,4,5, 6-pentafluorobenzonitrile for reaction; after the reaction is finished, water is added for precipitation and quenching, dichloromethane is used for extraction, and column chromatography is used for purification;

or the like, or, alternatively,

reacting 3-hydroxy carbazole, cesium carbonate, 4-iodine-N, N-diphenylaniline and N, N-dimethylformamide for 3-5h at 90-110 ℃ under the protection of nitrogen, collecting a reaction product, and purifying by column chromatography; adding the purified product obtained in the previous step and sodium hydride into dried tetrahydrofuran for reaction, and then adding 2,3,4,5, 6-pentafluorobenzonitrile for reaction; after the reaction is finished, water is added for precipitation and quenching, dichloromethane is used for extraction, and column chromatography is used for purification;

or the like, or, alternatively,

reacting 3, 6-dihydroxy-9-hydrogen-carbazole, cesium carbonate, 2- (4-iodophenyl) -9,9' -spirobi [ fluorene ] and N, N-dimethylformamide at 90-110 ℃ for 3-5h under the protection of nitrogen, collecting a reaction product, and purifying by column chromatography; adding the purified product obtained in the previous step and sodium hydride into dried tetrahydrofuran for reaction, and then adding 2,3,4,5, 6-pentafluorobenzonitrile for reaction; after the reaction is finished, water is added for precipitation and quenching, dichloromethane is used for extraction, and column chromatography is used for purification;

or the like, or, alternatively,

reacting 3-hydroxycarbazole, cesium carbonate, 2- (4-iodophenyl) -9,9' -spirobifluorene and N, N-dimethylformamide at 90-110 ℃ for 3-5h under the protection of nitrogen, collecting a reaction product, and purifying by column chromatography; adding the purified product obtained in the previous step and sodium hydride into dried tetrahydrofuran for reaction, and then adding 2,3,4,5, 6-pentafluorobenzonitrile for reaction; after the reaction is finished, water is added for precipitation and quenching, dichloromethane is used for extraction, and column chromatography is used for purification.

7. Use of the solution processable thermally activated delayed fluorescence material according to claim 1 in the wet preparation of organic electroluminescent devices.

Technical Field

The invention relates to an organic luminescent material, a preparation method and application thereof, in particular to a thermally activated delayed fluorescence material capable of being processed by solution.

Background

Organic Light Emitting Diodes (OLEDs) are known as a new display with great research prospects because of their advantages of low driving voltage, fast response, high light emitting efficiency, simple manufacturing process, and easy realization of full color display. Whereas thermally activated delayed fluorescence materials (TADF) achieve 100% internal quantum efficiency due to their ability to fully exploit singlet excitons. Therefore, TADF materials are widely used in organic light emitting diodes. To date, researchers of TADF materials have focused on improving the performance of organic light emitting diode devices and their color purity.

In the case of small-molecule TADF materials, researchers have achieved tremendous success in both these areas. There are still some challenges that restrict the realization of large-scale commercial production of such superior materials. For example, the micromolecule thermal activation delayed fluorescence material with better performance is not suitable for being applied to devices prepared by a wet method because of relatively smaller molecular weight, smaller steric hindrance and easy agglomeration. Therefore, most of the small-molecule thermal activation delayed fluorescence materials are manufactured into devices by a vacuum evaporation method. However, compared with the wet preparation process, the preparation process has the disadvantages of complex flow and high equipment requirement, so that the cost is high, and the large-scale commercial production is not easy to realize.

The polymer thermal activation delayed fluorescent material has large molecular weight, large steric hindrance, difficult agglomeration and good film forming property, can be used for preparing devices by wet methods such as ink-jet printing or spin coating, and has great research potential in the aspect of large-area panel display. However, the polymer thermal activation delayed fluorescence material has a long synthetic route, more side reactions, higher purification difficulty, smaller luminescence brightness and efficiency and a plurality of low molecules, so the research progress is slow at present.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a novel solution-processable thermally-activated delayed fluorescence material which is used for improving the problems of the existing organic material in a device prepared by a wet method. Another object of the present invention is to provide a method for preparing the thermally activated delayed fluorescence material. The invention also aims to point out the application of the thermal activation delayed fluorescence material in the preparation of organic electroluminescent devices by a wet method.

The technical scheme is as follows: the solution-processable thermal activation delayed fluorescence material comprises a molecular structure, wherein the molecular structure consists of two parts, one part is a nucleus with thermal activation delayed fluorescence property, and the other part is a structure with high triplet state energy level, and the specific structure is as follows:

wherein R is₁、R₂At most one of them is hydrogen, the others are all structures linked through a benzene ring and oxygen, and the oxygen linkage has a high triplet level.

The solution-processable thermally-activated delayed fluorescence material has the following core structure with the thermally-activated delayed fluorescence property:

the solution-processable thermally-activated delayed fluorescence material has a structure with a high triplet energy level, wherein the structure is any one of the following structures:

the solution-processable thermally activated delayed fluorescence material has a molecular structure selected from the following chemical structural formulas:

the preparation method of the thermal activation delayed fluorescence material capable of being processed by solution comprises the steps of firstly preparing peripheral branches, then connecting the peripheral branches with a benzene ring through nucleophilic substitution, and finally connecting the peripheral branches with a core with thermal activation delayed fluorescence property inside through a carbon-nitrogen coupling reaction, thereby finally obtaining the dendritic thermal activation delayed fluorescence material.

The preparation method of the heat activation delayed fluorescence material capable of being processed by solution specifically comprises the following steps:

reacting 3, 6-dihydroxy-9-hydrogen-carbazole, cesium carbonate, 9- (4-iodophenyl) -9H-carbazole and N, N-dimethylformamide at 90-110 ℃ for 3-5H under the protection of nitrogen, collecting a reaction product, and purifying by column chromatography to obtain 3, 6-bis (4- (9H-carbazole-9-yl) phenoxy) -9H-carbazole; adding 3, 6-bis (4- (9H-carbazole-9-yl) phenoxy) -9H-carbazole and sodium hydride into dried tetrahydrofuran for reaction, then adding 2,3,4,5, 6-pentafluorobenzonitrile, stirring for reaction, adding water for quenching after the reaction is finished, extracting by dichloromethane, and purifying by column chromatography;

or the like, or, alternatively,

reacting 3-hydroxy carbazole, cesium carbonate, 9- (4-iodophenyl) -9H-carbazole and N, N-dimethylformamide at 90-110 ℃ for 3-5H under the protection of nitrogen, collecting reaction products, and purifying by column chromatography; adding the purified product obtained in the previous step and sodium hydride into dried tetrahydrofuran for reaction, and then adding 2,3,4,5, 6-pentafluorobenzonitrile for reaction; after the reaction is finished, water is added for precipitation and quenching, dichloromethane is used for extraction, and the column chromatography is used for purification;

or the like, or, alternatively,

reacting 3, 6-dihydroxy-9-hydrogen-carbazole, cesium carbonate, 4-iodo-N, N-diphenylaniline and N, N-dimethylformamide at 90-110 ℃ for 3-5h under the protection of nitrogen, collecting a reaction product, and purifying by column chromatography; adding the purified product obtained in the previous step and sodium hydride into dried tetrahydrofuran for reaction, and then adding 2,3,4,5, 6-pentafluorobenzonitrile for reaction; after the reaction is finished, adding water for separating out and quenching, extracting by using dichloromethane, and purifying by using a column chromatography;

or the like, or, alternatively,

reacting 3-hydroxy carbazole, cesium carbonate, 4-iodine-N, N-diphenylaniline and N, N-dimethylformamide for 3-5h at 90-110 ℃ under the protection of nitrogen, collecting a reaction product, and purifying by column chromatography; adding the purified product obtained in the previous step and sodium hydride into dried tetrahydrofuran for reaction, and then adding 2,3,4,5, 6-pentafluorobenzonitrile for reaction; after the reaction is finished, water is added for precipitation and quenching, dichloromethane is used for extraction, and the column chromatography is used for purification;

or the like, or, alternatively,

reacting 3, 6-dihydroxy-9-hydrogen-carbazole, cesium carbonate, 2- (4-iodophenyl) -9,9' -spirobi [ fluorene ] and N, N-dimethylformamide at 90-110 ℃ for 3-5h under the protection of nitrogen, collecting a reaction product, and purifying by column chromatography; adding the purified product obtained in the previous step and sodium hydride into dried tetrahydrofuran for reaction, and then adding 2,3,4,5, 6-pentafluorobenzonitrile for reaction; after the reaction is finished, water is added for precipitation and quenching, dichloromethane is used for extraction, and column chromatography is used for purification;

or the like, or, alternatively,

reacting 3-hydroxycarbazole, cesium carbonate, 2- (4-iodophenyl) -9,9' -spirobifluorene and N, N-dimethylformamide at 90-110 ℃ for 3-5h under the protection of nitrogen, collecting a reaction product, and purifying by column chromatography; adding the purified product obtained in the previous step and sodium hydride into dried tetrahydrofuran for reaction, and then adding 2,3,4,5, 6-pentafluorobenzonitrile for reaction; after the reaction is finished, water is added for precipitation and quenching, dichloromethane is used for extraction, and column chromatography is used for purification.

The thermal activation delayed fluorescence material capable of being processed by solution is applied to the preparation of an organic electroluminescent device by a wet method.

Has the advantages that: the novel solution processable thermally activated delayed fluorescence material of the present application consists of two parts, one part being a core with thermally activated delayed fluorescence properties and the other part being a linked structure with a high triplet energy level. It is neither a small molecule nor a polymer material, but has the excellent performance of a small molecule and the good film-forming property of a polymer molecule due to the steric hindrance effect of a peripheral branch chain connected with the small molecule. The steric hindrance effect of the peripheral branched chain can effectively reduce the concentration quenching of triplet excitons and improve the performance of the luminescent device; the preparation and purification method is simpler than that of the polymer. The novel material shows excellent device performance in the non-doping process, the power efficiency and the external quantum efficiency of the novel material are more than 2 times of those of an internal nuclear device, and the device performance is greatly improved along with the increase of peripheral branched chains. Therefore, the material has unique advantages in the process of preparing devices by a wet method, and is suitable for thermally-activated delayed fluorescence materials of devices prepared by the wet method.

Detailed Description

For further understanding of the present invention, the present invention is specifically illustrated below with reference to specific examples, but the following examples are only for further illustrating the present invention and do not limit the present invention.