阅读说明：本技术 一种深蓝光热交联型热激活延迟荧光材料及其制备方法与应用 (Deep blue photo-thermal crosslinking type thermal activation delayed fluorescence material and preparation method and application thereof ) 是由 孙开涌 周璐瑶 滕玉玲 蔡超逸 邹永斌 蔡照胜 于 2020-05-29 设计创作，主要内容包括：一种深蓝光热交联型热激活延迟荧光材料及其制备方法与应用,属于有机光电材料与有机发光二极管器件领域。本发明所述深蓝光热交联型热激活延迟荧光材料为DV-2CzBN,其结构式为<Image he="109" wi="235" file="100004_DEST_PATH_IMAGE001.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>。本发明所述制备方法简单,制备的材料热交联形成聚合物的温度低,热交联后的聚合物薄膜具有成膜性能好,稳定性好以及抗溶剂侵蚀强等优点,便于进一步电子传输材料的旋涂,提高材料的利用率、降低器件制作成本,基于材料制备的全湿法有机发光二极管器件,电致光谱波长为448 nm,外量子效率高达7.8%。(A deep blue photo-thermal cross-linking type thermal activation delayed fluorescence material and a preparation method and application thereof belong to the field of organic photoelectric materials and organic light emitting diode devices. The deep blue photothermal crosslinking type thermal activation delayed fluorescence material is DV-2CZBN, and the structural formula of the material is . The preparation method is simple, the temperature of the prepared material for forming the polymer by thermal crosslinking is low, and the polymer film after thermal crosslinking has good film-forming propertyThe all-wet organic light-emitting diode device prepared based on the material has the advantages of high stability, strong solvent corrosion resistance and the like, is convenient for further spin coating of an electron transport material, improves the utilization rate of the material, and reduces the manufacturing cost of the device, and the wavelength of an electric spectrum is 448 nm, and the external quantum efficiency is as high as 7.8%.)

1. The deep blue photo-thermal crosslinking thermal activation delayed fluorescence material is characterized by being DV-2CzBN, and the structural formula of the deep blue photo-thermal crosslinking thermal activation delayed fluorescence material is。

2. The preparation method of the deep blue photothermal crosslinking type thermally activated delayed fluorescence material according to claim 1, wherein the preparation method comprises the following steps:

step one, adding 3-methoxy carbazole into anhydrous tetrahydrofuran at room temperature, stirring and dissolving, adding sodium hydride, reacting for 0.5-2 hours, adding 3, 6-difluorobenzonitrile, reacting at the temperature of 60-80 ℃ for 12-24 hours under the protection of nitrogen, and after the reaction is finished, purifying a crude product by column chromatography to obtain a product of 2, 6-bis (3-methoxy-9 hydro-carbazolyl-9-yl) benzonitrile, wherein the molar ratio of the 3-methoxy carbazole to the sodium hydride to the 3, 6-difluorobenzonitrile is 1: (2-3): (0.4-0.5);

step two, adding the 2, 6-bis (3-methoxy-9 hydrogen-carbazolyl-9-yl) benzonitrile obtained in the step one into chloroform, stirring and dissolving, then dropwise adding a boron tribromide solution, reacting at 0 ℃, reacting for 3-6 hours, quenching with a methanol solution after the reaction is finished, and spin-drying an organic solvent to obtain the product 2, 6-bis (3-hydroxy-9 hydrogen-carbazolyl-9-yl) benzonitrile, wherein the molar ratio of the 2, 6-bis (3-methoxy-9 hydrogen-carbazolyl-9-yl) benzonitrile to the boron tribromide is 1: (1-2);

adding the 2, 6-bis (3-hydroxy-9 hydrogen-carbazolyl-9-yl) benzonitrile obtained in the step two into dry N, N-dimethylformamide, stirring for dissolving, adding sodium hydride for reaction, adding 4-chloro-methylstyrene for reaction after 0.5-2 hours, wherein the reaction temperature is 60-80 ℃, the reaction time is 12-24 hours, and after the reaction is finished, purifying by column chromatography to obtain the deep blue photothermal activation delayed fluorescent material, wherein the ratio of the 2, 6-bis (3-hydroxy-9 hydrogen-carbazolyl-9-yl) benzonitrile, the sodium hydride and the 4-chloro-methylstyrene is 1: (2-4): (3-5).

3. The method for preparing a deep blue photothermal crosslinking type thermally activated delayed fluorescence material as claimed in claim 2, wherein the eluent for column chromatography in the first step and the third step is a mixed solution of petroleum ether and dichloromethane.

4. The use of the deep blue photothermal crosslinking type thermally activated delayed fluorescence material of claim 1 in the preparation of a full wet process deep blue organic light emitting diode.

5. The application of claim 4, wherein the specific application process is as follows:

cleaning an anode electrode, respectively cleaning the anode electrode with deionized water, ethanol, acetone and isopropanol, drying the anode electrode under an infrared lamp, and finally cleaning the anode electrode with ultraviolet ozone for half an hour for later use;

spin-coating a hole transport layer on the upper surface of the anode at the rotating speed of 3000rpm, and heating and annealing in a nitrogen atmosphere after the spin-coating is finished;

spin-coating a deep blue light cross-linking type thermally-activated delayed fluorescent material on the upper surface of the hole transport layer to serve as a light emitting layer, wherein the rotating speed is 1500-3000 rpm, and heating and cross-linking are carried out in a nitrogen atmosphere after the spin-coating is finished;

and step four, spin-coating an alcohol-soluble electron transmission material on the upper surface of the light-emitting layer to serve as an electron transmission layer, wherein the rotation speed is 1500-3000 rpm, heating and annealing in a nitrogen atmosphere after the spin-coating is finished, and then evaporating a cathode to obtain the all-wet-process deep blue light organic electroluminescent diode.

6. The use as claimed in claim 5, wherein the temperature of the annealing in the second step and the fourth step is 80-120 ℃ for 20min, and the temperature of the crosslinking in the third step is 120-200 ℃ for 10 min.

7. The use according to claim 5, wherein the anode electrode in step one is Indium Tin Oxide (ITO).

8. The use according to claim 5, wherein the hole transport layer in step two is PEDOT with a molecular weight of 8000 g/mol: PSS, having the following structural formula:

。

9. the use of claim 5, wherein in step three the alcohol-soluble electron transport material is PO-T2T, having the formula:

10. an all-wet deep blue organic light emitting diode prepared by the use of any one of claims 4 to 9.

Technical Field

The invention relates to the field of organic photoelectric materials and organic light-emitting diode devices, in particular to a deep blue photo-thermal crosslinking type thermal activation delayed fluorescence material and a preparation method and application thereof.

Background

Thermal Activated Delayed Fluorescence (TADF) materials have become the latest generation fluorescent materials in the application of Organic Light Emitting Diodes (OLEDs) because they do not contain noble metals and can trap singlet and triplet excitons to achieve 100% theoretical internal quantum efficiency. Up to now, a large number of high efficiency evaporation-type OLEDs based on TADF small molecule materials have been reported. Especially aiming at the problems of high cost, strong toxicity, poor luminous stability and the like of deep blue light phosphorescent materials, scientific researchers make a lot of efforts in the aspect of developing novel deep blue light TADF materials and obtain better results. Adachi et al (Angew, chem., Int, Ed.2017, 56, 1571-1575) reported deep blue TADF small molecule materials based on triazine and carbazole groups with maximum external quantum efficiency of up to 19.2% for evaporated devices and color coordinates of (0.148, 0.098). Subsequently, the group (adv. funct. mater. 2018, 30, 1705641) reported deep blue TADF small molecule materials based on benzonitrile and carbazole groups, with maximum external quantum efficiency of up to 10.3% for evaporated devices, with color coordinates (0.156, 0.063). However, most of the currently reported deep blue OLEDs adopt an evaporation process, and have the disadvantages of high equipment investment and maintenance cost, low organic material utilization rate, difficulty in realizing large-area preparation, and the like. In contrast, solution methods are generally simple and inexpensive, and offer significant advantages over large area and flexible devices. Therefore, the development of the deep blue TADF material processed by the solution method has very important significance.

The TADF polymer material has good wet film-forming property and solvent corrosion resistance, and is an excellent material for processing wet solution OLED devices. Andrey et al (adv. Mater. 2015, 27, 7236-7240) first reported that TADF polymer materials were prepared by metal-catalyzed polymerization of host and guest components, avoiding the influence of phase separation and achieving 100% exciton utilization. Ding et al report a red TADF polymer material with a device emission wavelength of 606 nm, a maximum external quantum efficiency of 5.6%, and a current efficiency of 10.3 cd/A. Yan et al report green TADF polymer materials with maximum external quantum efficiencies of up to 20.1% for the devices, with color coordinates (0.36, 0.55). Subsequently, Wang et al reported that the maximum external quantum efficiency of the device was 12.1% and the color coordinates were (0.18, 0.27) for a blue TADF polymer material based on space charge transfer effects. Notably, most of the currently published TADF polymer materials have emission wavelengths in the range of 470-610 nm, and little is important for the development of deep blue TADF polymer materials.

Disclosure of Invention

The technical problem to be solved is as follows: aiming at the technical problems, the invention provides a deep blue photothermal crosslinking type thermal activation delayed fluorescence material and a preparation method and application thereof, the preparation method has simple process, the temperature of the polymer formed by thermal crosslinking of the prepared material is low, the polymer film after thermal crosslinking has the advantages of good film forming property, good stability, strong solvent corrosion resistance and the like, the spin coating of an electron transport material is facilitated, the utilization rate of the material is improved, and the manufacturing cost of a device is reduced, and the full-wet method organic light emitting diode device prepared based on the material has the advantages that the wavelength of an electroluminescence spectrum is 448 nm, and the external quantum efficiency is as high as 7.8%.

The technical scheme is as follows: the deep blue photo-thermal crosslinking thermal activation delayed fluorescence material is DV-2CzBN, and the structural formula of the deep blue photo-thermal crosslinking thermal activation delayed fluorescence material is DV-2CzBN。

One technical scheme of the invention is a preparation method of the deep blue photothermal crosslinking type thermally activated delayed fluorescence material, which comprises the following steps:

step one, adding 3-methoxy carbazole into anhydrous tetrahydrofuran at room temperature, stirring and dissolving, adding sodium hydride, reacting for 0.5-2 hours, adding 3, 6-difluorobenzonitrile, reacting at the temperature of 60-80 ℃ for 12-24 hours under the protection of nitrogen, and after the reaction is finished, purifying a crude product by column chromatography to obtain a product of 2, 6-bis (3-methoxy-9 hydro-carbazolyl-9-yl) benzonitrile, wherein the molar ratio of the 3-methoxy carbazole to the sodium hydride to the 3, 6-difluorobenzonitrile is 1: (2-3): (0.4-0.5);

step two, adding the 2, 6-bis (3-methoxy-9 hydrogen-carbazolyl-9-yl) benzonitrile obtained in the step one into chloroform, stirring and dissolving, then dropwise adding a boron tribromide solution, reacting at 0 ℃, reacting for 3-6 hours, quenching with a methanol solution after the reaction is finished, and spin-drying an organic solvent to obtain the product 2, 6-bis (3-hydroxy-9 hydrogen-carbazolyl-9-yl) benzonitrile, wherein the molar ratio of the 2, 6-bis (3-methoxy-9 hydrogen-carbazolyl-9-yl) benzonitrile to the boron tribromide is 1: (1-2);

adding the 2, 6-bis (3-hydroxy-9 hydrogen-carbazolyl-9-yl) benzonitrile obtained in the step two into dry N, N-dimethylformamide, stirring for dissolving, adding sodium hydride for reaction, adding 4-chloro-methylstyrene for reaction after 0.5-2 hours, wherein the reaction temperature is 60-80 ℃, the reaction time is 12-24 hours, and after the reaction is finished, purifying by column chromatography to obtain the deep blue photothermal activation delayed fluorescent material, wherein the ratio of the 2, 6-bis (3-hydroxy-9 hydrogen-carbazolyl-9-yl) benzonitrile, the sodium hydride and the 4-chloro-methylstyrene is 1: (2-4): (3-5).

Preferably, the eluent for column chromatography in the first step and the third step is a mixed solution of petroleum ether and dichloromethane.

One technical scheme of the invention is application of the deep blue photothermal crosslinking type thermal activation delayed fluorescence material in preparation of a full-wet-method deep blue organic light-emitting diode.

Preferably, the specific application process is as follows:

cleaning an anode electrode, respectively cleaning the anode electrode with deionized water, ethanol, acetone and isopropanol, drying the anode electrode under an infrared lamp, and finally cleaning the anode electrode with ultraviolet ozone for half an hour for later use;

spin-coating a hole transport layer on the upper surface of the anode at the rotating speed of 3000rpm, and heating and annealing in a nitrogen atmosphere after the spin-coating is finished;

spin-coating a deep blue light cross-linking type thermally-activated delayed fluorescent material on the upper surface of the hole transport layer to serve as a light emitting layer, wherein the rotating speed is 1500-3000 rpm, and heating and cross-linking are carried out in a nitrogen atmosphere after the spin-coating is finished;

and step four, spin-coating an alcohol-soluble electron transmission material on the upper surface of the light-emitting layer to serve as an electron transmission layer, wherein the rotation speed is 1500-3000 rpm, heating and annealing in a nitrogen atmosphere after the spin-coating is finished, and then evaporating a cathode to obtain the all-wet-process deep blue light organic electroluminescent diode.

Preferably, the temperature of the heating annealing in the second step and the fourth step is 80-120 ℃ and the time is 20min, and the temperature of the heating crosslinking in the third step is 120-200 ℃ and the time is 10 min.

Preferably, in the first step, the anode electrode is indium tin oxide ITO.

Preferably, the hole transport layer in the second step is PEDOT with a molecular weight of 8000 g/mol: PSS, having the following structural formula:

。

preferably, the alcohol-soluble electron transport material in step three is PO-T2T, and the structural formula is as follows:

。

the other technical scheme of the invention is the all-wet-process deep blue light organic light-emitting diode prepared by the application.

Has the advantages that: 1. the deep blue photothermal crosslinking type thermal activation delayed fluorescence material molecule has low temperature for forming the polymer through thermal crosslinking, the thermal crosslinking polymerization method can avoid the redissolution process of the polymer, the polymer synthesis and the luminescent layer film manufacturing process are combined into a whole, and the device manufacturing process is simplified.

2. The polymer film prepared by thermal crosslinking has the advantages of good film-forming property, good stability, strong solvent corrosion resistance and the like, is convenient for further spin coating of an electronic transmission material, and can improve the utilization rate of the material and reduce the manufacturing cost of a device.

3. According to the all-wet organic light emitting diode device, the wavelength of an electroluminescence spectrum is 448 nm, the external quantum efficiency is up to 7.8%, compared with the currently reported OLED (Macromolecules 2019, 52, 2296-.

Drawings

FIG. 1 is a schematic diagram of a molecular structural formula of the material and an organic light emitting diode structure;

FIG. 2 is a nuclear magnetic hydrogen spectrum of the material prepared in example 1 of the present invention;

fig. 3 is an electroluminescence spectrum of the organic light emitting diode device in example 1.

In the figure: each numerical designation is as follows: 1. an anode electrode; 2. a hole transport layer; 3. a light emitting layer; 4. an electron transport layer; 5. and a cathode electrode.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the specific contents of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

The materials used in the present invention are as follows:

wherein the materials Indium Tin Oxide (ITO), PEDOT: PSS, PO-T2T, aluminum and cesium carbonate are all commercially available.