A thermally activated delayed fluorescent material based on pillar[5]arene derivatives, its preparation method and OLED application

Abstract

The present invention discloses a thermally activated delayed fluorescent material based on pillar[5]arene derivatives, a preparation method thereof, and an OLED application. The structural formula of the material is #imgabs0#, wherein: R is a host unit, which is 9-hexyl-9-hydro-carbazole, 9'-hexyl-9'-hydro-9,3':6',9''-tricarbazole, 9-(4-(hexyloxy)phenyl)-hexyloxy-9-hydro-carbazole or 9,9'-(5-(hexyloxy)-1,3-phenylene)bis(9-hydro-carbazole); R1 is a guest luminescent unit, which is 2,3,5,6-tetra(3,6-di-tert-butyl-9-hydro-carbazolyl-9-yl)-4-(4-(hexyloxy)phenoxy)benzonitrile. The material has a high relative molecular mass and solubility of non-conjugated alkyl chains, ensuring that the molecule has good film-forming properties, and solves the problem that traditional host-guest material doped wet process devices are prone to phase separation.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic optoelectronic materials and devices, and specifically relates to a thermally activated delayed fluorescent material based on pillar[5]arene derivatives, a preparation method thereof, and OLED applications. Background Art

[0002] Organic light-emitting diode (OLED) display panels offer advantages such as rollability, fast response, self-luminescence, and lightweight materials, representing a new generation of flat-panel display and lighting technology. After decades of development, OLED technology has matured and is gradually entering the market, with related products penetrating all aspects of the display industry. Most OLED products currently on the market utilize a vacuum evaporation process, where organic materials are heated, vaporized, and deposited onto a substrate under a high vacuum atmosphere to form the functional and light-emitting layers. This method is complex, has low material utilization, high production costs, and is not suitable for the production of large-scale devices. Consequently, most OLED products currently on the market are small to medium-sized, such as smartphones and watches. Compared to traditional evaporation processes, solution processing offers a simpler preparation process and higher material utilization, making it more suitable for the development of large-scale OLED devices.

[0003] The development of organic electroluminescent materials has always been the foundation of OLED technology. The selection of luminescent materials is closely related to the luminous efficiency, preparation process and production cost of OLED devices. The development of low-cost, high-luminous-efficiency and high-stability luminescent materials remains a challenge. Thermally activated delayed fluorescence (TADF) materials have been favored by scientific researchers since their report. Compared with traditional first-generation fluorescent materials and second-generation phosphorescent materials, TADF materials do not contain precious metals and can achieve a theoretical internal quantum efficiency of 100% by utilizing triplet exciton anti-gap crossing. Therefore, the development of TADF polymers is an important direction for ideal wettable luminescent materials.

[0004] However, the wet-process luminescent materials in the existing technology have phase separation problems caused by the doping of host and guest materials, which easily lead to efficiency roll-off and difficulty in achieving blue light emission, which limits the further application of this type of material. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to provide a thermally activated delayed fluorescence material based on columnar [5] aromatic hydrocarbon derivatives, its preparation method and OLED application, which has the following characteristics: ① The main unit in the molecular structure has good hole transport performance to ensure efficient carrier injection and high triplet energy level to ensure effective transfer of energy from the main to the guest; ② The guest luminescent unit in the molecular structure has thermally activated delayed fluorescence performance and high fluorescence quantum yield to ensure 100% theoretical internal quantum efficiency to achieve efficient luminescence; ③ The molecule has a high relative molecular mass and solubility of non-conjugated alkyl chains, which ensures that the molecule has good film-forming performance and is suitable for the production of wet-process OLED devices; ④ The molecule has the characteristics of a self-host and can be used for the preparation of wet-process non-doped devices, avoiding the problem of phase separation that is prone to occur in traditional host-guest doped wet devices.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] The first object of the present invention is to provide a thermally activated delayed fluorescent material based on pillar[5]arene derivatives, the structural formula of which is In the formula: R is a main unit, which is 9-hexyl-9-hydro-carbazole, 9'-hexyl-9'-hydro-9,3':6',9"-tricarbazole, 9-(4-(hexyloxy)phenyl)-hexyloxy-9-hydro-carbazole or 9,9'-(5-(hexyloxy)-1,3-phenylene)bis(9-hydro-carbazole); R1 is a guest light-emitting unit, which is 2,3,5,6-tetrakis(3,6-di-tert-butyl-9-hydro-carbazolyl-9-yl)-4-(4-(hexyloxy)phenoxy)benzonitrile.

[0008] Specifically, when R is 9-hexyl-9-hydrogen-carbazole, 9'-hexyl-9'-hydrogen-9,3':6',9"-tricarbazole, 9-(4-(hexyloxy)phenyl)-hexyloxy-9-hydrogen-carbazole, and 9,9'-(5-(hexyloxy)-1,3-phenylene)bis(9-hydrogen-carbazole), the corresponding thermally activated delayed fluorescent materials are abbreviated as PE1, PE2, PE3, and PE4, respectively, and their molecular structures are as follows:

[0009]

[0010] The second object of the present invention is to provide a method for preparing a thermally activated delayed fluorescent material based on pillar[5]arene derivatives as described in the first object, comprising the following steps:

[0011] (1) Preparation of brominated guest luminescent units

[0012] 1,4-hydroquinone, 1,6-dibromohexane, and KOH are added to a solvent and dissolved, the solvent is heated under reflux conditions to react for 2-6 hours, and the resulting product is purified by column chromatography to obtain an intermediate product 1;

[0013] The intermediate product 1 is dissolved in a solvent, 2,3,4,5,6-pentafluorobenzonitrile and potassium carbonate are added, and the mixture is reacted at 80°C-120°C for 3-6 hours. The obtained product is purified by column chromatography to obtain the intermediate product 2;

[0014] The intermediate product 2 is dissolved in a solvent, 3,6-di-tert-butylcarbazole and sodium hydride are added, and the reaction is carried out in a protective gas atmosphere at a reaction temperature of 0°C-40°C. After the reaction, the obtained product is purified by column chromatography to obtain a brominated guest light-emitting unit; preferably, the molar ratio of the intermediate product 2, 3,6-di-tert-butylcarbazole, and sodium hydride is 1:(5-10):(20-30).

[0015] The reaction formula involved in the above method is as follows:

[0016]

[0017] (2) Preparation of target product

[0018] The brominated guest luminescent unit is dissolved in a solvent, and decahydroxy-pentabenzocyclodecane and potassium hydroxide are added, wherein the molar ratio of the brominated guest luminescent unit, decahydroxy-pentabenzocyclodecane and potassium hydroxide is 1:1:(2-5). After reacting at a temperature of 80°C-110°C for 1-2 hours, a reaction raw material containing a main unit structure is added, and the reaction is continued for 12h-24h. The resulting product is purified by column chromatography to obtain the target product, i.e., a thermally activated delayed fluorescent material based on column [5] aromatic derivatives.

[0019] Specifically, the reaction raw materials containing the main unit structure are brominated 9-hexyl-9-hydrogen-carbazole, brominated 9'-hexyl-9'-hydrogen-9,3':6',9"-tricarbazole, brominated 9-(4-(hexyloxy)phenyl)-hexyloxy-9-hydrogen-carbazole or brominated 9,9'-(5-(hexyloxy)-1,3-phenylene)bis(9-hydrogen-carbazole); correspondingly, the reaction formulas of the prepared thermally activated delayed fluorescent materials PE1, PE2, PE3, and PE4 are as follows:

[0020]

[0021] It should be noted that the solvent used in the above preparation steps can be selected from N,N-dimethylformamide. Of course, other organic solvents with similar properties can also achieve the purpose of the present invention. Those skilled in the art can select other solvents with similar properties to replace the N,N-dimethylformamide in the present invention as needed, and all of them fall within the scope of protection of the present invention.

[0022] A third object of the present invention is to provide a use of a thermally activated delayed fluorescent material based on a pillar[5]arene derivative, wherein the thermally activated delayed fluorescent material based on a pillar[5]arene derivative is used to prepare a wet-process organic electroluminescent diode. The steps for preparing the wet-process organic electroluminescent diode are as follows:

[0023] (1) Cleaning the anode electrode with detergent, water, ethanol, acetone, and isopropyl alcohol respectively, then drying it with infrared light, and finally cleaning it with ultraviolet ozone before use;

[0024] (2) Spin coating a hole transport layer material on the anode, and drying the material after spin coating to form a hole transport layer; preferably, the hole transport layer material is PEDOT:PSS, and the structural formula is Molecular weight is 8000 g / mol;

[0025] (3) spin coating the thermally activated delayed fluorescent material based on the pillar[5]arene derivative as claimed in claim 1 on the hole transport layer, and placing it in a protective gas atmosphere for drying after the spin coating is completed to form a light-emitting layer;

[0026] (4) Spin-coating a layer of electron transport layer material on the light-emitting layer, and drying after the spin coating is completed to form an electron transport layer; preferably, the electron transport layer material is PO-T2T, and the structural formula is

[0027] (5) A cathode is evaporated on the surface of the electron transport layer to obtain a wet-process blue light-emitting organic electroluminescent diode.

[0028] The fourth object of the present invention is to provide an organic electroluminescent diode prepared by applying the thermally activated delayed fluorescent material based on the pillar[5]arene derivative as described in the third object.

[0029] Beneficial effects:

[0030] 1. The activated delayed fluorescent material based on pillar[5]arene derivatives provided by the present invention has a high relative molecular mass and solubility of non-conjugated alkyl chains; the material uses pillar[5]arene as a skeleton and, through host-guest unit modification, avoids the phase separation problem caused by traditional host-guest material doping during device preparation, and is easy to form a light-emitting layer film with good stability.

[0031] 2. The main unit in this molecular structure has good hole transport properties, ensuring efficient carrier injection and high triplet energy levels, ensuring effective energy transfer from the main body to the guest; at the same time, the guest luminescent unit in this molecular structure has thermally activated delayed fluorescence properties and high fluorescence quantum yield, ensuring 100% theoretical internal quantum efficiency to achieve efficient luminescence.

[0032] 3. The OLED device prepared by the delayed fluorescent material activated by the pillar[5]arene derivative provided by the present invention exhibits blue light emission, with the highest external quantum efficiency reaching 27.6%. When the device brightness is 100 cd m -2 The efficiency roll-off is only 2.9%, showing excellent electroluminescent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the structure of the organic light emitting diode prepared by the present invention;

[0034] The numbers in the figure represent the following: 1. ITO anode; 2. hole transport layer; 3. light-emitting layer; 4. electron transport layer; 5. metal cathode;

[0035] Figure 2 This is the external quantum efficiency spectrum of the OLED device prepared in Application Examples 1-4. DETAILED DESCRIPTION

[0036] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the specific content of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] The materials used in the following examples are as follows:

[0038]

[0039] Example 1

[0040] Preparation of thermally activated delayed fluorescent materials (PE1) based on pillar[5]arene derivatives:

[0041] The structural formula of PE1 is:

[0042]

[0043] The synthesis method is:

[0044] 1,4-Hydroquinone, 1,6-dibromohexane, and KOH were weighed in a molar ratio of 1:1:2 and added to an N,N-dimethylformamide solution. The reaction temperature was set at 110°C and the reaction was refluxed for 6 hours. After completion of the reaction, intermediate product 1 was purified by column chromatography. Intermediate product 1 was dissolved in N,N-dimethylformamide with stirring. 2,3,4,5,6-pentafluorobenzonitrile and potassium carbonate were added. The molar ratio of intermediate product 1, 2,3,4,5,6-pentafluorobenzonitrile, and potassium carbonate was 1:1:2. The reaction temperature was set at 80°C and the reaction time was set for 3 hours. After completion of the reaction, intermediate product 2 was purified by column chromatography. Intermediate product 2 was dissolved in N,N-dimethylformamide with stirring. 3,6-di-tert-butylcarbazole and sodium hydride were added. The molar ratio of intermediate product 2, 3,6-di-tert-butylcarbazole, and sodium hydride was 1:5:20. The reaction was carried out in a nitrogen atmosphere at a reaction temperature of 0° C. for 24 hours. After the reaction was completed, the brominated guest luminescent unit was purified by column chromatography.

[0045] The brominated guest luminescent unit was added to N,N-dimethylformamide and stirred to dissolve, and then decahydroxy-pentabenzocyclodecane and potassium hydroxide were added. The molar ratio of the brominated guest luminescent unit, decahydroxy-pentabenzocyclodecane, and potassium hydroxide was 1:1:2. The reaction temperature was 110°C and the reaction time was 2 hours. Brominated 9-hexyl-9-hydrogen-carbazole was added, and the molar ratio of the brominated guest luminescent unit to the brominated guest luminescent unit was 10:1. The reaction was carried out in a nitrogen atmosphere at a reaction temperature of 110°C and a reaction time of 24 hours. After the reaction was completed, the column [5] aromatic derivative thermally activated delayed fluorescent material was obtained by purification by column chromatography. The molecular structure analysis results are as follows: PE1, mass spectrum: 4152.30; elemental analysis: C: 80.34, H: 7.78, N: 4.72.

[0046] Application Example 1

[0047] The thermally activated delayed fluorescent material prepared in Example 1 was used to prepare a wet-process blue light OLED device. The schematic diagram of the device is shown in FIG. Figure 1 As shown, the components are: ITO / PEDOT:PSS (30nm) / PE1 (30nm) / PO-T2T (40nm) / Cs2CO3 (1nm) / Al (100nm). The specific process of preparing the device is as follows:

[0048] 1. Cleaning of indium tin oxide (ITO) glass substrate: Use detergent, deionized water, ethanol, acetone, and isopropyl alcohol to ultrasonically clean the ITO, three times for each solvent, then dry it under infrared light for 1 hour, and finally clean it with ultraviolet ozone for half an hour before use.

[0049] 2. Spin coating of the hole transport layer: A 40 nm thick anode buffer layer of PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid)) was spin-coated on the ITO surface at 2000 rpm. The substrate was then dried on a hot plate at 120°C for 20 minutes to form the hole transport layer.

[0050] 3. Preparation of the light-emitting layer: After cooling to room temperature, 1 mL of 1,2-dichloroethane containing 10 mg / mL PE1 was spin-coated on the surface of the hole transport layer at a speed of 2000 rpm for 30 seconds. The layer was then dried in a nitrogen atmosphere at 200°C for 10 minutes and cooled to room temperature to form a light-emitting layer.

[0051] 4. Spin coating of the electron transport layer: Spin coat a 40nm thick layer of PO-T2T (5mg / mL) on the surface of the light-emitting layer at 2000rpm. Next, dry the substrate on a hot plate at 120°C for 20 minutes to form the electron transport layer.

[0052] 5. Evaporation deposition of cathode: and Cs2CO3 and Al were evaporated on the surface of the electron transport layer at a rate as the cathode to obtain an OLED device.

[0053] Device performance testing: Luminance-current-voltage curves were measured in a glove box using a Kethiey 2400 semiconductor performance test system connected to an ST-86LA screen luminance meter. Electroluminescence spectra and color coordinates were also measured using a PR655 spectrometer.

[0054] The device performance is as follows: the lighting voltage is 3.1V, the maximum brightness is 15400cd / m 2 , the maximum external quantum efficiency is 12.6%.

[0055] Example 2

[0056] Preparation of thermally activated delayed fluorescent materials (PE2) based on pillar[5]arene derivatives:

[0057] The structural formula of PE2 is:

[0058]

[0059] The synthesis method is:

[0060] The brominated guest luminescent unit in Example 1 was added to N,N-dimethylformamide and stirred to dissolve, and then decahydroxy-pentabenzocyclodecane and potassium hydroxide were added in a molar ratio of 1:1:2, the reaction temperature was 110°C, and the reaction time was 2 hours. Brominated 9'-hexyl-9'hydro-9,3':6',9"-tricarbazole was added in a molar ratio of 10:1 to the brominated guest luminescent unit. The reaction was carried out in a nitrogen atmosphere at a reaction temperature of 110°C for 24 hours. After the reaction was completed, the column [5] aromatic derivative thermally activated delayed fluorescent material was obtained by purification by column chromatography. The molecular structure analysis results are as follows: PE2, mass spectrum: 7122.60; elemental analysis: C: 86.26, H: 6.43, N: 6.29.

[0061] Application Example 2

[0062] Preparation of wet-process blue OLED devices:

[0063] The schematic diagram of the device structure is: ITO / PEDOT:PSS (30nm) / PE2 (30nm) / PO-T2T (40nm) / Cs2CO3 (1nm) / Al (100nm), as shown in Figure 2. Figure 1 The specific process of device preparation is as follows:

[0064] 1. Cleaning of indium tin oxide (ITO) glass substrate: Use detergent, deionized water, ethanol, acetone, and isopropyl alcohol to ultrasonically clean the ITO, three times for each solvent, then dry it under infrared light for 1 hour, and finally clean it with ultraviolet ozone for half an hour before use.

[0065] 2. Spin coating of the hole transport layer: A 40 nm thick anode buffer layer of PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid)) was spin-coated on the ITO surface at 2000 rpm. The substrate was then dried on a hot plate at 120°C for 20 minutes to form the hole transport layer.

[0066] 3. Preparation of the Light-Emitting Layer: After cooling to room temperature, spin-coat 1 mL of 1,2-dichloroethane containing 10 mg / mL PE2 onto the hole transport layer at 2000 rpm for 30 seconds. Dry the mixture under a nitrogen atmosphere at 200°C for 10 minutes before cooling to room temperature to form the light-emitting layer.

[0067] 4. Spin coating of the electron transport layer: Spin coat a 40nm thick layer of PO-T2T (5mg / mL) on the surface of the light-emitting layer at 2000rpm. Next, dry the substrate on a hot plate at 120°C for 20 minutes to form the electron transport layer.

[0068] 5. Evaporation deposition of cathode: and Cs2CO3 and Al were evaporated on the surface of the electron transport layer at a rate as the cathode to obtain an OLED device.

[0069] The device performance is as follows: the lighting voltage is 3.3V, the maximum brightness is 21600cd / m 2 , the maximum external quantum efficiency is 18.1%.

[0070] Example 3

[0071] Preparation of thermally activated delayed fluorescent materials (PE3) based on pillar[5]arene derivatives:

[0072] The structural formula of PE3 is:

[0073]

[0074] The synthesis method is:

[0075] The brominated guest luminescent unit in Example 1 was added to N,N-dimethylformamide and stirred to dissolve, and then decahydroxy-pentabenzocyclodecane and potassium hydroxide were added in a molar ratio of 1:1:2, the reaction temperature was 110°C, and the reaction time was 2 hours. Brominated 9-(4-(hexyloxy)phenyl)-hexyloxy 9-hydrogen-carbazole was added in a molar ratio of 10:1 to the brominated guest luminescent unit. The reaction was carried out in a nitrogen atmosphere at a temperature of 110°C for 24 hours. After the reaction was completed, the column [5] aromatic derivative thermally activated delayed fluorescent material was obtained by purification by column chromatography. The molecular structure analysis results are as follows: PE3, mass spectrum: 4980.72; elemental analysis: C: 83.12, H: 7.19, N: 3.94.

[0076] Application Example 3

[0077] Preparation of wet-process blue OLED devices:

[0078] The schematic diagram of the device structure is: ITO / PEDOT:PSS (30nm) / PE3 (30nm) / PO-T2T (40nm) / Cs2CO3 (1nm) / Al (100nm), as shown in Figure 2. Figure 1 The specific process of device preparation is as follows:

[0079] 1. Cleaning of indium tin oxide (ITO) glass substrate: Use detergent, deionized water, ethanol, acetone, and isopropyl alcohol to ultrasonically clean the ITO, three times for each solvent, then dry it under infrared light for 1 hour, and finally clean it with ultraviolet ozone for half an hour before use.

[0080] 2. Spin coating of the hole transport layer: A 40 nm thick anode buffer layer of PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid)) was spin-coated on the ITO surface at 2000 rpm. The substrate was then dried on a hot plate at 120°C for 20 minutes to form the hole transport layer.

[0081] 3. Preparation of the Light-Emitting Layer: After cooling to room temperature, spin-coat 1 mL of 1,2-dichloroethane containing 10 mg / mL PE3 material onto the hole transport layer at 2000 rpm for 30 seconds. Dry the mixture under a nitrogen atmosphere at 200°C for 10 minutes before cooling to room temperature to form the light-emitting layer.

[0082] 4. Spin coating of the electron transport layer: Spin coat a 40nm thick layer of PO-T2T (5mg / mL) on the surface of the light-emitting layer at 2000rpm. Next, dry the substrate on a hot plate at 120°C for 20 minutes to form the electron transport layer.

[0083] 5. Evaporation deposition of cathode: and Cs2CO3 and Al were evaporated on the surface of the electron transport layer at a rate as the cathode to obtain an OLED device.

[0084] The device performance is as follows: the lighting voltage is 3.2V, the maximum brightness is 26500cd / m 2 , the maximum external quantum efficiency is 19.2%.

[0085] Example 4

[0086] Preparation of thermally activated delayed fluorescent materials (PE4) based on pillar[5]arene derivatives:

[0087] The structural formula of PE4 is:

[0088]

[0089] The synthesis method is:

[0090] The brominated guest luminescent unit in Example 1 was added to N,N-dimethylformamide and stirred to dissolve, and then decahydroxy-pentabenzocyclodecane and potassium hydroxide were added in a molar ratio of 1:1:2, the reaction temperature was 110°C, and the reaction time was 2 hours. Brominated 9,9'-(5-(hexyloxy)-1,3-phenylene)bis(9-hydrogen-carbazole) was added in a molar ratio of 10:1 to the brominated guest luminescent unit. The reaction was carried out in a nitrogen atmosphere at a temperature of 110°C for 24 hours. After the reaction was completed, the column [5] aromatic derivative thermally activated delayed fluorescent material was obtained by purification by column chromatography. The molecular structure analysis results are as follows: PE4, mass spectrum: 6465.4; elemental analysis: C: 85.01, H: 6.51, N: 4.98.

[0091] Application Example 4

[0092] Preparation of wet-process blue OLED devices:

[0093] The schematic diagram of the device structure is: ITO / PEDOT:PSS (30nm) / PE4 (30nm) / PO-T2T (40nm) / Cs2CO3 (1nm) / Al (100nm), as shown in Figure 2. Figure 1 The specific process of device preparation is as follows:

[0094] 1. Cleaning of indium tin oxide (ITO) glass substrate: Use detergent, deionized water, ethanol, acetone, and isopropyl alcohol to ultrasonically clean the ITO, three times for each solvent, then dry it under infrared light for 1 hour, and finally clean it with ultraviolet ozone for half an hour before use.

[0095] 2. Spin coating of the hole transport layer: A 40 nm thick anode buffer layer of PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid)) was spin-coated on the ITO surface at 2000 rpm. The substrate was then dried on a hot plate at 120°C for 20 minutes to form the hole transport layer.

[0096] 3. Preparation of the Light-Emitting Layer: After cooling to room temperature, spin-coat 1 mL of 1,2-dichloroethane containing 10 mg / mL PE4 material onto the hole transport layer at 2000 rpm for 30 seconds. Dry the mixture under a nitrogen atmosphere at 200°C for 10 minutes before cooling to room temperature to form the light-emitting layer.

[0097] 4. Spin coating of the electron transport layer: Spin coat a 40nm thick layer of PO-T2T (5mg / mL) on the surface of the light-emitting layer at 2000rpm. Next, dry the substrate on a hot plate at 120°C for 20 minutes to form the electron transport layer.

[0098] 5. Evaporation deposition of cathode: and Cs2CO3 and Al were evaporated on the surface of the electron transport layer at a rate as the cathode to obtain an OLED device.

[0099] The device performance is as follows: the lighting voltage is 2.9V and the maximum brightness is 31600cd / m 2 , the maximum external quantum efficiency is 27.6%.

[0100] Figure 2 The external quantum efficiency spectra of the devices prepared in Application Examples 1 to 4 are as follows: Figure 2 It can be seen that the device obtained in Application Example 4 exhibits excellent electroluminescent performance. 2 and 1000cd / m 2 The device still maintains a high external quantum efficiency and the efficiency roll-off is very small.

[0101] Obviously, the embodiments and application examples described above are suitable illustrations of the purpose of the present invention, but these examples are not intended to limit the present invention. Any simple modification of the present invention without departing from the principle of the present invention also falls within the scope of protection of the claims of the present invention.

Claims

1. A thermally activated delayed fluorescent material based on pillar[5]arene derivatives, characterized in that: Its structural formula is , wherein: R is the main unit, which is 9-hexyl-9-hydrogen-carbazole, 9'-hexyl-9'-hydrogen-9,3':6',9''-tricarbazole, 9-(4-(hexyloxy)phenyl)-hexyloxy-9-hydrogen-carbazole or 9,9'-(5-(hexyloxy)-1,3-phenylene)bis(9-hydrogen-carbazole); R1 is the guest light-emitting unit, which is 2,3,5,6-tetrakis(3,6-di-tert-butyl-9-hydrogen-carbazolyl-9-yl)-4-(4-(hexyloxy)phenoxy)benzonitrile; wherein R and R1 are both hexyl parts connected to the main structure.

2. The method for preparing a thermally activated delayed fluorescent material based on pillar[5]arene derivatives according to claim 1, characterized in that: The following steps are involved: (1) Preparation of brominated guest luminescent units 1,4-hydroquinone, 1,6-dibromohexane, and KOH are added to a solvent and dissolved, and the solvent is heated under reflux conditions to react for 2-6 hours, and the resulting product is purified to obtain an intermediate product 1; the structural formula of the intermediate product 1 is ; The intermediate product 1 is dissolved in a solvent, 2,3,4,5,6-pentafluorobenzonitrile and potassium carbonate are added, and the reaction is carried out at a temperature of 80°C-120°C for 3-6 hours. The obtained product is purified to obtain the intermediate product 2; the structural formula of the intermediate product 2 is ; The intermediate product 2 is dissolved in a solvent, 3,6-di-tert-butylcarbazole and sodium hydride are added, and the reaction is carried out in a protective gas atmosphere at a reaction temperature of 0°C-40°C. After the reaction is completed, the obtained product is purified to obtain a brominated guest luminescent unit; the structural formula of the brominated guest luminescent unit is ; (2) Preparation of target product The brominated guest luminescent unit is dissolved in a solvent, decahydroxy-pentabenzocyclodecane and potassium hydroxide are added, and the reaction is carried out at a temperature of 80°C-110°C for 1-2 hours. Then, a reaction raw material containing a main unit structure is added, and the reaction is continued for 12h-24h. The resulting product is purified to obtain the target product, that is, a thermally activated delayed fluorescent material based on a column [5] aromatic hydrocarbon derivative; the reaction raw material containing the main unit structure is brominated 9-hexyl-9-hydrogen-carbazole, brominated 9'-hexyl-9'-hydrogen-9,3':6',9''-tricarbazole, brominated 9-(4-(hexyloxy)phenyl)-hexyloxy-9-hydrogen-carbazole or brominated 9,9'-(5-(hexyloxy)-1,3-phenylene)bis(9-hydrogen-carbazole).

3. The method for preparing a thermally activated delayed fluorescent material based on pillar[5]arene derivatives according to claim 2, characterized in that: The molar ratio of the intermediate product 2,3,6-di-tert-butylcarbazole and sodium hydride is 1:(5-10):(20-30).

4. The method for preparing a thermally activated delayed fluorescent material based on pillar[5]arene derivatives according to claim 2, characterized in that: The molar ratio of the brominated guest light-emitting unit, decahydroxy-pentabenzocyclodecane, and potassium hydroxide is 1:1:(2-5).

5. The use of a thermally activated delayed fluorescent material based on pillar[5]arene derivatives as claimed in claim 1, characterized in that: The thermally activated delayed fluorescent material based on pillar[5]arene derivatives is used to prepare wet-process organic electroluminescent diodes.

6. The use of a thermally activated delayed fluorescent material based on pillar[5]arene derivatives according to claim 5, characterized in that: The steps of preparing the wet-process organic electroluminescent diode are as follows: (1) Clean the anode electrode with detergent, water, ethanol, acetone, and isopropyl alcohol respectively, then dry it with infrared light, and finally clean it with ultraviolet ozone before use; (2) Spin coating the hole transport layer material on the anode, and drying it after the spin coating is completed to form a hole transport layer; (3) Spin coating the thermally activated delayed fluorescent material based on the pillar[5]arene derivative as claimed in claim 1 on the hole transport layer, and placing the material in a protective gas atmosphere for drying after the spin coating is completed to form a light-emitting layer; (4) Spin coating a layer of electron transport layer material on the light-emitting layer, and drying it after the spin coating is completed to form an electron transport layer; (5) A cathode is evaporated on the surface of the electron transport layer to obtain a wet-process blue light-emitting organic electroluminescent diode.

7. The use of a thermally activated delayed fluorescent material based on pillar[5]arene derivatives according to claim 6, characterized in that: In step (2), the hole transport layer material is PEDOT:PSS, and its structural formula is , with a molecular weight of 8000 g / mol; in step (4), the electron transport layer material is PO-T2T, whose structural formula is .

8. An organic electroluminescent diode prepared by using the thermally activated delayed fluorescent material based on the pillar[5]arene derivative according to any one of claims 5 to 7.

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