Preparation method and application of solution-processable hole transport material

Abstract

The invention relates to the field of organic functional semiconductor materials, in particular to a preparation method and application of a solution-processable hole transport material. The hole transport material takes a conjugated polymer with a triphenylamine, fluorene and carbazole structure as a parent nucleus, and carbon chains and groups with different lengths are in soluble expansion; compared with a traditional organic hole transport layer poly N, N '-diphenyl-N, N'-(1-naphthyl)-1, 1 'biphenyl-4, 4'-diamine (NPB), the novel hole transport material capable of being processed in the solution has good stability, hole transport performance, dissolvability and film-forming property, and is beneficial to large-area device preparation and cost reduction; the hole transport material has the advantages of being good in stability, easy to process, low in cost and the like, and the organic light-emitting diode with the structure made of the hole transport material with the structure shows the performance far better than that of the organic light-emitting diode in the market.

Description

Technical Field

[0001] This invention relates to the field of organic functional semiconductor materials technology, specifically to a method for preparing and applying a solution-processable hole transport material. Background Technology

[0002] Organic light-emitting diodes (OLEDs) possess advantages such as active light emission, high luminous efficiency, fast response speed, low power consumption, light weight, thinness, and no viewing angle limitations. They represent the next generation of display technology after liquid crystals and plasma displays, and are often referred to as "dream displays." OLEDs can be used not only as displays but also as lighting sources. These two major fields—display and lighting—give OLEDs enormous development prospects, resulting in vast application value and market potential. An organic light-emitting diode device is a multilayer thin-film structure, with each layer consisting of hole injection material, hole transport material, electron blocking material, light-emitting material, hole blocking material, electron transport material, and electron injection material, each with its unique function and application prospects. Molecular structure, thermal stability, morphology, molecular orbital energy levels, and the charge mobility of each layer are the primary considerations for obtaining high-efficiency and long-life organic light-emitting diodes.

[0003] Hole transport materials are a class of key semiconductor materials used for the efficient transport of hole carriers, and they have core application value in the OLED field. The highest occupied molecular orbital energy level of the hole transport layer needs to be matched with that of adjacent functional layers (such as the anode or perovskite layer) to reduce the hole injection barrier and improve charge separation efficiency. Polymer hole transport materials have good solubility and film-forming properties, which are beneficial for the fabrication of large-area devices, and they can be designed with three-dimensional structures to optimize energy levels. In addition, their high thermal decomposition temperature and UV resistance can extend device lifetime, and high hole mobility ensures rapid hole transport to the light-emitting layer or electrode, reducing recombination losses and improving device efficiency.

[0004] Solution-processable OLED materials offer significant advantages in large-size, flexible, and low-cost applications, and are poised to dominate future display markets such as televisions, automotive displays, and indoor / outdoor advertising. Traditional evaporation processes for organic optoelectronic materials suffer from waste due to metal mask obstruction, resulting in material utilization rates generally below 30%, making them unsuitable for direct printing. Solution-processable materials, on the other hand, directly support flexible substrates, achieving utilization rates exceeding 90%. Furthermore, solution-processable materials offer significant advantages in both equipment investment and material costs. Therefore, developing novel solution-processable organic hole transport materials is a crucial current research direction. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing and applying an organic hole transport material that is solution-processable, has high hole mobility, and is suitable for fabrication of large-area devices, in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a solution-processable hole transport material. The hole transport material uses a conjugated polymer with a triphenylamine, fluorene, and carbazole structure as its core. By adjusting the side chain length or substituents, the solubility and processability of the material can be improved. The structure of the hole transport material is shown below:

[0008] ;

[0009] Where X, Y, and Z can be 0.1-0.9 respectively;

[0010] R1 is one of methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, 2-ethylhexyl, 2-octyldecyl, monomethyl ether or monoethyl ether oligoethylene glycol ethyl, substituted or unsubstituted phenyl, biphenyl, naphthyl, anthracene, furanyl, carbazole, thiophene, dibenzofuranyl;

[0011] R2 is one or more of the following: methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, 2-ethylhexyl, 2-octyldecyl, monomethyl ether or monoethyl ether oligoethylene glycol ethyl;

[0012] -N-(R3,R4) is one of the following groups:

[0013] .

[0014] Furthermore, the solution-processable hole transport material comprises the following structure:

[0015]

[0016]

[0017]

[0018]

[0019] .

[0020] This invention also provides a method for preparing a solution-processable hole transport material, the process route of which is as follows:

[0021] .

[0022] Specifically, the process includes the following steps: adding a palladium catalyst to a carbazole derivative, a triphenylamine derivative, and 9,9-dioctyl-2,7-dibromofluorene, and preparing a solution-processable hole transport material through a palladium-catalyzed Suzuki coupling reaction.

[0023] 1. Further, the molar ratio of carbazole derivative, triphenylamine derivative, 9,9-dioctyl-2,7-dibromofluorene, and palladium catalyst is 0.05~0.95, 0.05~0.95, 0.05~0.95, and 0.0001~0.01.

[0024] The present invention also provides the application of the solution-processable hole transport material described above in organic light-emitting diodes.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] This invention utilizes a carbazole derivative, a triphenylamine derivative, and a fluorene derivative to form an asymmetric conjugated structure, precisely adjusting the band gap and energy level positions, enhancing the molecular dipole moment, and resulting in higher hole mobility and conductivity. The asymmetric design optimizes molecular packing and film morphology, enhancing thermal and environmental stability while maintaining good solution processability and film-forming properties, which is beneficial for large-area preparation and commercial applications. Furthermore, the asymmetric conjugated molecular framework facilitates the introduction of substituents, enabling structural modification and functionalization, and modulating electronic effects and intermolecular forces, thereby optimizing photoelectric properties.

[0027] The present invention discloses a solution-processable hole transport material with better stability and hole transport performance, as well as good solubility and film-forming properties, which is beneficial for the fabrication of large-area devices and cost reduction. Organic light-emitting diodes made with hole transport material of this structure exhibit superior overall performance. Attached Figure Description

[0028] Figure 1 This is a molecular structure diagram of the hole transport material of the present invention. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] This invention provides a method for preparing a novel solution-processable hole transport material as described above, comprising the steps of: reacting 4-R1 aniline with iodobenzene to prepare 4-R1-N,N-diphenylaniline, and reacting 4-R1-N,N-diphenylaniline with N-bromosuccinimide to prepare R1-TPA.

[0031] This invention provides a method for preparing a novel solution-processable hole transport material as described above, comprising the steps of: reacting 2,7-dibromofluorene with a halogenated R2 to prepare 2,7-dibromo-9,9-diR2fluorene; reacting 2,7-dibromo-9,9-diR2fluorene with triisopropylboronic acid to prepare 2,7-diboronic acid-9,9-diR2fluorene; and reacting 2,7-diboronic acid-9,9-diR2fluorene with propylene glycol to prepare the fluorene derivative R2-FL.

[0032] This invention provides a method for preparing a novel solution-processable hole transport material as described above, comprising the steps of: reacting 3,6-dibromocarbazole with p-fluoroiodobenzene via a nucleophilic substitution reaction to prepare N-(4-iodophenyl)-3,6-dibromocarbazole, and coupling N-(4-iodophenyl)-3,6-dibromocarbazole with HNR3R4 via CN coupling to prepare the carbazole derivative NR3R4-CZ.

[0033] This invention provides a method for preparing a novel solution-processable hole transport material as described above, comprising the steps of: preparing a series of novel solution-processable hole transport materials SPHTM by palladium-catalyzed Suzuki coupling reaction of carbazole derivative, triphenylamine derivative and 9,9-dioctyl-2,7-dibromofluorene.

[0034]

[0035] in,

[0036] X, Y, and Z can be 0.1-0.9 respectively;

[0037] R1 is one of the following: hydrogen atom, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, 2-ethylhexyl, 2-octyldecyl, monomethyl ether or monoethyl ether oligoethylene glycol ethyl, substituted or unsubstituted phenyl, biphenyl, naphthyl, anthracene, furanyl, carbazole, thiophene, dibenzofuranyl;

[0038] R2 is one or more of the following: methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, 2-ethylhexyl, 2-octyldecyl, monomethyl ether or monoethyl ether oligoethylene glycol ethyl;

[0039] Alternatively, -N-(R3,R4) can be any of the following groups:

[0040]

[0041] The hole transport materials described above, using the conjugated polymer structure of fluorene, triphenylamine, and carbazole as the parent core and varying carbon chain lengths and functional groups as soluble extensions, exhibit significantly superior performance. The conjugated structure of fluorene, triphenylamine, and carbazole possesses good stability and a high triplet energy level, which enhances the HOMO level and facilitates hole carrier transfer. The varying carbon chain lengths and functional groups contribute to improved solubility and film formation, making device fabrication easier and less costly.

[0042] Example 1

[0043] 1) The preparation steps of the triphenylamine derivative n-Bu-TPA-2Br are as follows:

[0044]

[0045] In a 1 L dry three-necked flask, 0.1 mol of 4-butylaniline, 0.22 mol of iodobenzene, 0.01 mol of cuprous iodide, 0.25 mol of sodium hydroxide, 0.02 mol of 1,10-phenanthroline, and 400 mL of toluene were added and stirred to dissolve. The mixture was then evacuated three times. The reaction was carried out in an oil bath at 125 °C for 24 hours. After the reaction was complete, the mixture was cooled to room temperature, filtered through diatomaceous earth to remove the palladium catalyst, washed with dichloromethane, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by column chromatography using dichloromethane:petroleum ether (1:15) as the eluent to obtain a pale yellow solid product, n-Bu-TPA (yield 65.1%).

[0046] In a 1 L dry three-necked flask, n-Bu-TPA (0.1 mol) and 1,2-dichloroethane (400 mL) were added, stirred to dissolve, and the mixture was evacuated three times. N-bromosuccinimide (NBS, 0.2 mol) was added in three portions at room temperature, and the reaction was carried out in an 80 °C oil bath for 48 hours. After the reaction was complete, the mixture was cooled to room temperature, quenched with a saturated sodium thiosulfate solution, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by column chromatography using dichloromethane:petroleum ether (1:25) as the eluent to obtain a pale yellow solid, n-Bu-TPA-2Br (yield 92.3%).

[0047] 2) The preparation steps of the fluorene derivative 2Oc-FL are as follows:

[0048]

[0049] In a 1 L three-necked flask, 0.1 mol of 2,7-dibromofluorene, 300 mL of 50% NaOH aqueous solution, and 0.01 mol of tetrabutylammonium iodide (TBAI) were added. The mixture was purged three times, and then 1-bromo-n-octane was added. The mixture was reacted in an oil bath at 70 °C for 4 hours. After cooling to room temperature, the mixture was extracted with dichloromethane. The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The solution was purified by column chromatography using ethyl acetate:petroleum ether (1:9) as the eluent to give 2Oc-FL-2Br in 86.2% yield.

[0050] In a 1 L dry three-necked flask, 0.08 mol of 2Oc-FL-2Br and 700 mL of anhydrous tetrahydrofuran were added. The mixture was cooled to -78 °C, and the atmosphere was evacuated three times. 2.5 M 100 mL of n-butyllithium was slowly added dropwise. After the addition was complete, the reaction was continued at -78 °C for 1.5 hours. Then, 0.2 mol of triisopropyl borate was slowly added dropwise. After the addition was complete, the reaction was continued at -78 °C for 12 hours. The reaction was monitored by TLC. Once the reaction was complete, the mixture was brought to room temperature, and 500 mL of 1 M hydrochloric acid solution was added. The mixture was stirred at room temperature for 5 hours. Ethyl acetate was added for extraction three times. The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. 2Oc-FL-2BOH was purified by column chromatography using ethyl acetate:petroleum ether (1:2) as the eluent, with a yield of 85.6%.

[0051] In a 1 L dry three-necked flask, 0.05 mol of 2Oc-FL-2BOH, 0.12 mol of 1,3-propanediol, and 400 mL of anhydrous diethyl ether were added. The mixture was stirred at room temperature for 12 hours, and the solvent was removed by rotary evaporation. The 2Oc-FL was purified by column chromatography using ethyl acetate:petroleum ether (1:6) as the eluent, with a yield of 82.5%.

[0052] 3) The preparation steps of the carbazole derivative BP-TP-CZ are as follows:

[0053]

[0054] 0.21 mol of 3,6-dibromocarbazole, 0.2 mol of p-fluoroiodobenzene, 0.3 mol of cesium carbonate, and 150 mL of N,N-dimethylformamide (DMF) were added to a 500 mL three-necked flask, and the mixture was reacted in an oil bath at 150 °C for 24 hours. After cooling to room temperature, deionized water was added to precipitate the product, which was then filtered and washed successively with deionized water and methanol. The crude product on the filter cake was recrystallized from methanol to give a white solid product, 3,6-dibromocarbazole-9-(4-iodophenyl)-9H-carbazole (yield 80.6%).

[0055]

[0056] N-(4-phenylphenyl)-N-(3',5'-diphenylphenyl)amine (0.06 mol), 3,6-dibromocarbazole-9-(4-iodophenyl)-9H-carbazole (0.06 mol), tris(dibenzylacetone)palladium (0.003), tri-tert-butylphosphine (0.006), sodium tert-butoxide (0.01), and toluene (400 mL) were added, with the mixture being purged three times. The reaction was carried out in a 90 °C oil bath for 12 hours. After the reaction was complete, the mixture was cooled to room temperature, filtered through diatomaceous earth to remove the palladium catalyst, washed with dichloromethane, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by column chromatography using dichloromethane:petroleum ether (1:3) as the eluent to obtain a pale yellow solid product BP-TP-CZ (yield 51.8%).

[0057] 4) The preparation steps of the novel solution-processable hole transport material SPHTM-1 are as follows:

[0058]

[0059] In a 500 mL pressure-resistant flask, add n-Bu-TPA-2Br (0.03 mol), 2Oc-FL (0.03 mol), BP-TP-CZ (0.05 mol), Pd-P(t-bu)3-G4 (3 mmol), potassium trimethylsilanolate (TMSOK, 0.3 mol), methyltrioctylammonium chloride (Aliquat@336, 1 mmol), and toluene (300 mL). Purge the atmosphere three times and react in an oil bath at 120 °C for 72 hours. After cooling to room temperature, add propanol phenylborate (0.03 mol) and Pd-P(t-bu)3-G4 (3 mol). Purge the atmosphere three times and continue reacting overnight. After cooling to room temperature, stop the reaction, filter the reaction solution through diatomaceous earth, and wash with tetrahydrofuran. The filtrate was added to methanol and stirred for 1 hour. The crude product was filtered to obtain the precipitated product. The crude product was purified by Soxhlet extraction with methanol, petroleum ether and acetone respectively to obtain the pale yellow solid product SPHTM-1 (yield 76.2%).

[0060] Example 2

[0061] 1) The preparation steps of the triphenylamine derivative t-Bu-TPA-2Br are as follows:

[0062]

[0063] In a 1 L dry three-necked flask, 0.1 mol of 4-tert-butylaniline, 0.22 mol of iodobenzene, 0.01 mol of cuprous iodide, 0.25 mol of sodium hydroxide, 0.02 mol of 1,10-phenanthroline, and 400 mL of toluene were added and stirred to dissolve. The mixture was then evacuated three times. The reaction was carried out in an oil bath at 125 °C for 24 hours. After the reaction was complete, the mixture was cooled to room temperature, filtered through diatomaceous earth to remove the palladium catalyst, washed with dichloromethane, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by column chromatography using dichloromethane:petroleum ether (1:15) as the eluent to obtain a pale yellow solid product t-Bu-TPA (yield 55.1%).

[0064] In a 1 L dry three-necked flask, t-Bu-TPA (0.1 mol) and 1,2-dichloroethane (400 mL) were added, stirred to dissolve, and the mixture was evacuated three times. N-bromosuccinimide (NBS, 0.2 mol) was added in three portions at room temperature, and the reaction was carried out in an oil bath at 80 °C for 48 hours. After the reaction was complete, the mixture was cooled to room temperature, quenched with a saturated sodium thiosulfate solution, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by column chromatography using dichloromethane:petroleum ether (1:25) as the eluent to obtain a pale yellow solid, t-Bu-TPA-2Br (yield 91.2%).

[0065] 2) The preparation steps of the fluorene derivative 2Eh-FL are as follows:

[0066]

[0067] In a 1 L three-necked flask, 0.1 mol of 2,7-dibromofluorene, 300 mL of 50% NaOH aqueous solution, and 0.01 mol of tetrabutylammonium iodide were added. The mixture was purged three times, and then 0.3 mol of 2-ethylhexyl bromide was added. The mixture was reacted in an oil bath at 70 °C for 4 hours. After cooling to room temperature, the mixture was extracted with dichloromethane, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The solution was purified by column chromatography using ethyl acetate:petroleum ether (1:10) as the eluent to obtain 2Eh-FL-2Br in 90.5% yield.

[0068] In a 1 L dry three-necked flask, 0.08 mol of 2Eh-FL-2Br and 700 mL of anhydrous tetrahydrofuran were added. The mixture was cooled to -78 °C, and the atmosphere was evacuated three times. 2.5 M 100 mL of n-butyllithium was slowly added dropwise. After the addition was complete, the reaction was continued at -78 °C for 1.5 hours. Then, 0.2 mol of triisopropyl borate was slowly added dropwise. After the addition was complete, the reaction was continued at -78 °C for 12 hours. The reaction was monitored by TLC. Once the reaction was complete, the mixture was brought to room temperature, and 500 mL of 1 M hydrochloric acid solution was added. The mixture was stirred at room temperature for 5 hours. Ethyl acetate was added for extraction three times. The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. 2Eh-FL-2BOH was purified by column chromatography using ethyl acetate:petroleum ether (1:3) as the eluent, with a yield of 78.6%.

[0069] In a 1 L dry three-necked flask, 0.05 mol of 2Eh-FL-2BOH, 0.12 mol of 1,3-propanediol, and 400 mL of anhydrous diethyl ether were added. The mixture was stirred at room temperature for 12 hours, and the solvent was removed by rotary evaporation. 2Eh-FL was purified by column chromatography using ethyl acetate:petroleum ether (1:7) as the eluent, with a yield of 84.5%.

[0070] 3) The preparation steps of the carbazole derivative NA-TP-CZ are as follows:

[0071]

[0072] N-(1-naphthyl)-N-(3',5'-diphenylphenyl)amine (0.06 mol), 3,6-dibromocarbazole-9-(4-iodophenyl)-9H-carbazole (0.06 mol), tris(dibenzylacetone)dipalladium (0.003), tri-tert-butylphosphine (0.006), sodium tert-butoxide (0.01), and toluene (400 mL) were added, with the mixture being purged three times. The reaction was carried out in a 90 °C oil bath for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered through diatomaceous earth to remove the palladium catalyst, washed with dichloromethane, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by column chromatography using dichloromethane:petroleum ether (1:3) as the eluent to obtain a pale yellow solid product NA-TP-CZ (yield 49.6%).

[0073] 4) The preparation steps of the novel solution-processable hole transport material SPHTM-2 are as follows:

[0074]

[0075] Add 0.03 mol of t-Bu-TPA-2Br, 0.03 mol of 2Eh-FL, 0.05 mol of NA-TP-CZ, 3 mmol of Pd-P(t-bu)3-G4, 0.3 mol of potassium trimethylsilanolate, 1 mmol of methyltrioctylammonium chloride, and 300 mL of toluene to a 500 mL pressure-resistant flask. Purge the atmosphere three times and react in an oil bath at 120 °C for 72 hours. After cooling to room temperature, add 0.03 mol of propanol phenylborate and 3 mol of Pd-P(t-bu)3-G4. Purge the atmosphere three times and continue reacting overnight. Cool to room temperature, stop the reaction, filter the reaction solution through diatomaceous earth, and wash with tetrahydrofuran. The filtrate was added to methanol and stirred for 1 hour. The crude product was filtered to obtain the precipitated product. The crude product was purified by Soxhlet extraction with methanol, petroleum ether and acetone respectively to obtain the pale yellow solid product SPHTM-2 (yield 74.6%).

[0076] Example 3

[0077] 1) The preparation steps of the triphenylamine derivative 4-Ph-TPA-2Br are as follows:

[0078]

[0079] In a 1 L dry three-necked flask, 0.1 mol of 4-aminobiphenyl, 0.22 mol of iodobenzene, 0.01 mol of cuprous iodide, 0.25 mol of sodium hydroxide, 0.02 mol of 1,10-phenanthroline, and 400 mL of toluene were added and stirred to dissolve. The mixture was then evacuated three times. The reaction was carried out in an oil bath at 125 °C for 24 hours. After the reaction was complete, the mixture was cooled to room temperature, filtered through diatomaceous earth to remove the palladium catalyst, washed with dichloromethane, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by column chromatography using dichloromethane:petroleum ether (1:10) as the eluent to obtain a pale yellow solid product, 4-Ph-TPA (yield 52.7%).

[0080] In a 1 L dry three-necked flask, 0.1 mol of 4-Ph-TPA and 400 mL of 1,2-dichloroethane were added and stirred to dissolve. The mixture was then evacuated three times. N-bromosuccinimide (NBS, 0.2 mol) was added in three portions at room temperature, and the reaction was carried out in an oil bath at 80 °C for 48 hours. After the reaction was complete, the mixture was cooled to room temperature and quenched with a saturated sodium thiosulfate solution. The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by column chromatography using dichloromethane:petroleum ether (1:20) as the eluent to obtain a pale yellow solid, 4-Ph-TPA-2Br (yield 86.5%).

[0081] 2) The preparation steps of the fluorene derivative 2Ee-FL are as follows:

[0082]

[0083] In a 1 L three-necked flask, 0.1 mol of 2,7-dibromofluorene, 300 mL of 50% NaOH aqueous solution, and 0.01 mol of tetrabutylammonium iodide were added. After three purgings, 0.3 mol of 1-bromo-3,6,9,12-tetraoxotetradecane was added. The mixture was reacted in a 70°C oil bath for 4 hours. After cooling to room temperature, the mixture was extracted with dichloromethane, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The solution was purified by column chromatography using ethyl acetate as eluent to give 2Ee-FL-2Br in 87.3% yield.

[0084] In a 1 L dry three-necked flask, 0.08 mol of 2Ee-FL-2Br and 700 mL of anhydrous tetrahydrofuran were added. The mixture was cooled to -78 °C, and the atmosphere was purged three times. 2.5 M 100 mL of n-butyllithium was slowly added dropwise. After the addition was complete, the reaction was continued at -78 °C for 1.5 hours. Then, 0.2 mol of triisopropyl borate was slowly added dropwise. After the addition was complete, the reaction was continued at -78 °C for 12 hours. The reaction was monitored by TLC. Once the reaction was complete, the mixture was brought to room temperature, and 500 mL of 1 M hydrochloric acid solution was added. The mixture was stirred at room temperature for 5 hours. Ethyl acetate was added for extraction three times. The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. 2Ee-FL-2BOH was purified by column chromatography using ethyl acetate:methanol (20:1) as the eluent, with a yield of 87.2%.

[0085] In a 1 L dry three-necked flask, 0.05 mol of 2Ee-FL-2BOH, 0.12 mol of 1,3-propanediol, and 400 mL of anhydrous diethyl ether were added. The mixture was stirred at room temperature for 12 hours. The solvent was removed by rotary evaporation. 2Ee-FL was purified by column chromatography using ethyl acetate as the eluent, with a yield of 85.9%.

[0086] 3) The preparation steps of the carbazole derivative FL-BP-CZ are as follows:

[0087]

[0088] N-([1,1'-biphenyl]-3-yl)-9,9-dimethyl-9H-fluorene-2-amine (0.06 mol), 3,6-dibromocarbazole-9-(4-iodophenyl)-9H-carbazole (0.06 mol), tris(dibenzylacetone)dipalladium (0.003), tri-tert-butylphosphine (0.006), sodium tert-butoxide (0.01), and toluene (400 mL) were added, with the mixture being purged three times. The reaction was carried out in an oil bath at 90 °C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered through diatomaceous earth to remove the palladium catalyst, washed with dichloromethane, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by column chromatography using dichloromethane:petroleum ether (1:2) as the eluent to obtain a pale yellow solid product FL-BP-CZ (yield 55.8%).

[0089] 4) The preparation steps of the novel solution-processable hole transport material SPHTM-3 are as follows:

[0090]

[0091] Add 0.03 mol of 4-Ph-TPA-2Br, 0.03 mol of 2Ee-FL, 0.05 mol of FL-BP-CZ, 3 mmol of Pd-P(t-bu)3-G4, 0.3 mol of potassium trimethylsilanolate, 1 mmol of methyltrioctylammonium chloride, and 300 mL of toluene to a 500 mL pressure-resistant flask. Purge the atmosphere three times and react in an oil bath at 120 °C for 72 hours. After cooling to room temperature, add 0.03 mol of propanol phenylborate and 3 mol of Pd-P(t-bu)3-G4. Purge the atmosphere three times and continue reacting overnight. Cool to room temperature, stop the reaction, filter the reaction solution through diatomaceous earth, and wash with tetrahydrofuran. The filtrate was added to methanol and stirred for 1 hour. The crude product was filtered to obtain the precipitated product. The crude product was purified by Soxhlet extraction with methanol, petroleum ether and acetone respectively to obtain the pale yellow solid product SPHTM-3 (yield 65.6%).

[0092] Example 4

[0093] 1) The preparation steps of the triphenylamine derivative 4-Biph-TPA-2Br are as follows:

[0094]

[0095] In a 1 L dry three-necked flask, 0.1 mol of 4-amino-3'-phenylbiphenyl, 0.22 mol of iodobenzene, 0.01 mol of cuprous iodide, 0.25 mol of sodium hydroxide, 0.02 mol of 1,10-phenanthroline, and 400 mL of toluene were added and stirred to dissolve. The mixture was evacuated three times. The reaction was carried out in an oil bath at 125 °C for 24 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered through diatomaceous earth to remove the palladium catalyst, washed with dichloromethane, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by column chromatography using dichloromethane:petroleum ether (1:9) as the eluent to obtain a pale yellow solid product, 4-Biph-TPA (yield 65.1%).

[0096] In a 1 L dry three-necked flask, 0.1 mol of 4-Biph-TPA and 400 mL of 1,2-dichloroethane were added and stirred to dissolve. The mixture was then evacuated three times. N-bromosuccinimide (NBS, 0.2 mol) was added in three portions at room temperature, and the mixture was reacted in an oil bath at 80 °C for 48 hours. After the reaction was complete, the mixture was cooled to room temperature and quenched with a saturated sodium thiosulfate solution. The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by column chromatography using dichloromethane:petroleum ether (1:20) as the eluent to obtain a pale yellow solid, 4-Biph-TPA-2Br (yield 88.3%).

[0097] 2) The preparation steps of the fluorene derivative 2Do-FL are as follows:

[0098]

[0099] In a 1 L three-necked flask, 0.1 mol of 2,7-dibromofluorene, 300 mL of 50% NaOH aqueous solution, and 0.01 mol of tetrabutylammonium iodide were added. The mixture was purged three times, and 0.3 mol of 9-(bromomethyl)nonadecane was added. The mixture was reacted in an oil bath at 70 °C for 4 hours. After cooling to room temperature, the mixture was extracted with dichloromethane, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The solution was purified by column chromatography using ethyl acetate:petroleum ether (1:8) as eluent to obtain 2Do-FL-2Br in 88.6% yield.

[0100] In a 1 L dry three-necked flask, 0.08 mol of 2Do-FL-2Br and 700 mL of anhydrous tetrahydrofuran were added. The mixture was cooled to -78 °C, and the atmosphere was evacuated three times. 2.5 M 100 mL of n-butyllithium was slowly added dropwise. After the addition was complete, the reaction was continued at -78 °C for 1.5 hours. Then, 0.2 mol of triisopropyl borate was slowly added dropwise. After the addition was complete, the reaction was continued at -78 °C for 12 hours. The reaction was monitored by TLC. Once the reaction was complete, the mixture was brought to room temperature, and 500 mL of 1 M hydrochloric acid solution was added. The mixture was stirred at room temperature for 5 hours. Ethyl acetate was added for extraction three times. The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. 2Do-FL-2BOH was purified by column chromatography using ethyl acetate:petroleum ether (1:1) as the eluent, with a yield of 72.3%.

[0101] In a 1 L dry three-necked flask, 0.05 mol of 2Do-FL-2BOH, 0.12 mol of 1,3-propanediol, and 400 mL of anhydrous diethyl ether were added. The mixture was stirred at room temperature for 12 hours, and the solvent was removed by rotary evaporation. 2Do-FL was purified by column chromatography using ethyl acetate:petroleum ether (1:3) as the eluent, with a yield of 84.3%.

[0102] 3) The preparation steps of the carbazole derivative FL-TP-CZ are as follows:

[0103]

[0104] N-([1,1':3',1''-terphenyl]-5'-yl)-9,9-dimethyl-9H-fluorene-2-amine (0.06 mol), 3,6-dibromocarbazole-9-(4-iodophenyl)-9H-carbazole (0.06 mol), tris(dibenzylacetone)dipalladium (0.003), tri-tert-butylphosphine (0.006), sodium tert-butoxide (0.01), and toluene (400 mL) were added, with the mixture being purged three times. The reaction was carried out in an oil bath at 90 °C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered through diatomaceous earth to remove the palladium catalyst, washed with dichloromethane, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by column chromatography using dichloromethane:petroleum ether (2:5) as the eluent to obtain a pale yellow solid product FL-TP-CZ (yield 45.6%).

[0105] 4) The preparation steps of the novel solution-processable hole transport material SPHTM-4 are as follows:

[0106]

[0107] Add 0.03 mol of 4-Biph-TPA-2Br, 0.03 mol of 2Do-FL, 0.05 mol of FL-TP-CZ, 3 mmol of Pd-P(t-bu)3-G4, 0.3 mol of potassium trimethylsilanolate, 1 mmol of methyltrioctylammonium chloride, and 300 mL of toluene to a 500 mL pressure-resistant flask. Purge the atmosphere three times and react in an oil bath at 120 °C for 72 hours. After cooling to room temperature, add 0.03 mol of propanol phenylborate and 3 mol of Pd-P(t-bu)3-G4. Purge the atmosphere three times and continue reacting overnight. Cool to room temperature, stop the reaction, filter the reaction solution through diatomaceous earth, and wash with tetrahydrofuran. The filtrate was added to methanol and stirred for 1 hour. The crude product was filtered to obtain the precipitated product. The crude product was purified by Soxhlet extraction with methanol, petroleum ether and acetone respectively to obtain the pale yellow solid product SPHTM-3 (yield 65.6%).

[0108] Example 5

[0109] This invention employs thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) to investigate the thermal properties of the hole transport materials SPHTM-1, SPHTM-2, SPHTM-3, and SPHTM-4 in the embodiments under a nitrogen atmosphere, with a heating rate of 10 °C·min. -1 .

[0110] OLED device structures with only hole migration were fabricated: ITO / HAT-CN(10 nm) / SPHTM(100 nm) / HAT-CN(10 nm) / Al(100 nm), and the hole migration performance of SPHTM-1, SPHTM-2, SPHTM-3, and SPHTM-4 was investigated.

[0111] Table 1. Photoelectric performance parameters of the organic light-emitting diodes involved in this invention.

[0112]

[0113] Compared to the traditional organic hole transport layer poly(N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine) (NPB), this invention presents a novel solution-processable hole transport material that exhibits excellent stability and hole transport performance, as well as good solubility and film-forming properties, which is beneficial for large-area device fabrication and cost reduction. This type of hole transport material offers advantages such as good stability, ease of processing, and low cost. Organic light-emitting diodes (OLEDs) fabricated using this hole transport material demonstrate performance far superior to commercially available OLEDs.

[0114] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0115] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A solution-processable hole transport material, characterized in that, The hole transport material uses a conjugated polymer with a triphenylamine, fluorene, and carbazole structure as its core. By adjusting the side chain length or substituents, a series of hole transport materials are obtained. The structure of the hole transport material is shown below: ； Where X, Y, and Z can be 0.1-0.9 respectively; R1 is one of methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, 2-ethylhexyl, 2-octyldecyl, monomethyl ether or monoethyl ether oligoethylene glycol ethyl, substituted or unsubstituted phenyl, biphenyl, naphthyl, anthracene, furanyl, carbazole, thiophene, dibenzofuranyl; R2 is one or more of the following: methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, 2-ethylhexyl, 2-octyldecyl, monomethyl ether or monoethyl ether oligoethylene glycol ethyl; -N-(R3,R4) is one of the following groups: 。 2. The solution-processable hole transport material according to claim 1, characterized in that, Includes the following structure:

3.

4.

5.

6. 。 7. A method for preparing a solution-processable hole transport material as described in any one of claims 1-2, characterized in that, The process route of the preparation method is as follows: 。 8. The method for preparing a solution-processable hole transport material according to claim 3, characterized in that, Specifically, the following steps are included: A solution-processable hole transport material was prepared by adding a palladium catalyst to carbazole derivatives, triphenylamine derivatives, and 9,9-dioctyl-2,7-dibromofluorene, and then via a palladium-catalyzed Suzuki coupling reaction.

9. The method for preparing a solution-processable hole transport material according to claim 3, characterized in that, The molar ratios of carbazole derivative, triphenylamine derivative, 9,9-dioctyl-2,7-dibromofluorene, and palladium catalyst are 0.05~0.95, 0.05~0.95, 0.05~0.95, and 0.0001~0.01, respectively.

10. The application of the solution-processable hole transport material as described in any one of claims 1-2 in organic light-emitting diodes.

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