Star-like micromolecular cross-linked hole transport material, and preparation method therefor and use thereof

Abstract

A star-like micromolecular cross-linked hole transport material, and a preparation method therefor and the use thereof. Vinyl is introduced into a star-like micromolecular compound to make same be able to undergo a polymerization reaction so as to form a three-dimensional cross-linked network polymer having good stability and solvent resistance; therefore, the problem of deterioration in hole transport performance caused by a micromolecular hole transport material being prone to crystallization is solved, the problem of interlayer mutual dissolution during the process of preparing a photoelectric device by means of a solution method is also effectively solved, the selections of a luminescent layer material and a solvent are more diversified, and a device has better stability. The star-like micromolecular cross-linked hole transport material has a proper HOMO energy level, relatively high hole mobility and a relatively high triplet state energy level, and has good prospects in photoelectric devices, especially in organic photoluminescent devices.

Description

A star-shaped small molecule cross-linked hole transport material and its preparation method and application Technical Field

[0001] The present invention relates to the technical field of organic electroluminescence, and in particular to a star-shaped small molecule cross-linked hole transport material, a preparation method and application thereof, and a preparation method of a hole transport film. Background Art

[0002] Organic Light-Emitting Diode (OLED) has the characteristics of self-luminescence, wide viewing angle, low driving voltage, high luminous efficiency, easy large-area preparation and flexibility, and is widely used in the display and lighting fields.

[0003] OLED devices primarily consist of a conductive anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a metal cathode. These functional layers are primarily prepared using vacuum evaporation and solution processing. Vacuum evaporation is suitable for producing small-scale thin films and is currently the primary process for commercial OLED production. However, small molecule hole transport materials are susceptible to crystallization during device operation, leading to degradation of hole transport and device performance. Solution processing offers advantages in improving material utilization, simplifying device fabrication, and enabling the production of large-area devices, making it commercially viable. However, during solution processing, since most organic materials have similar solubility, the upper solution layer can dissolve the underlying material, creating interlayer miscibility. This interlayer miscibility can damage the device's functional thin films, inhibiting charge transfer and ultimately impacting device efficiency and lifespan. Cross-linked hole transport materials are small molecule hole transport materials that possess a hole transport molecule core and cross-linking groups. These materials combine the advantages of both small molecule and polymer hole transport materials. Uncross-linked small molecules are easy to synthesize, purify and modify. The three-dimensional network polymer formed after cross-linking is highly stable, which solves the problem of easy crystallization of small molecule hole transport materials in OLED devices prepared by vacuum evaporation. At the same time, it has good solvent resistance, which effectively solves the interlayer miscibility problem in OLED devices prepared by solution method.

[0004] Hole transport materials (HTMs) for solution processing should possess matching energy levels, high hole mobility, excellent solubility, good stability, and high triplet energy levels. Currently reported cross-linked HTMs suffer from low hole mobility and insufficient triplet energy levels, resulting in poor device performance and limiting their commercial application. Therefore, the development of cross-linked HTMs with high mobility and high triplet energy levels is crucial for the development of solution-processed OLED devices. Summary of the Invention

[0005] The present invention aims to address the interlayer miscibility issues faced by solution-processed OLED devices, as well as the low hole mobility and insufficient triplet energy levels of commonly used cross-linked hole transport materials. By providing a series of star-shaped small molecule cross-linked hole transport materials, these materials exhibit suitable HOMO energy levels, high hole mobility, and high triplet energy levels, resolving the interlayer miscibility issues and thereby improving the performance and lifespan of OLED devices.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a star-shaped small molecule cross-linked hole transport material having one or more of the chemical structures shown in Formula I or Formula II:

[0008] .

[0009] M1 in Formula I or Formula II is hydrogen, substituted or unsubstituted C 12 ~C 90 aromatic amine groups, substituted or unsubstituted C 12 ~C 90 Any one of the heteroaromatic amine groups.

[0010] M2 in Formula I or Formula II is substituted or unsubstituted C 12 ~C 90 One or more aromatic groups.

[0011] Preferably, M1 in Formula I or Formula II has one of the following structures:

[0012] ;

[0013] Preferably, M2 in Formula I or Formula II has one of the following structures:

[0014] .

[0015] Preferably, the star-shaped small molecule cross-linked hole transport material has one or more chemical structures represented by formulas HTM1 to HTM22:

[0016]

[0017]

[0018] The present invention also provides a method for preparing the star-shaped small molecule cross-linked hole transport material described in the above technical solution, comprising the following steps:

[0019] (1) Under inert gas protection, a first substitution reaction is carried out at 70-90 °C for 6-12 h using p-bromostyrene and aniline / 2-naphthylamine / 2-amino-9,9-dimethylfluorene / 4-aminobiphenyl / p-methylaniline / p-methoxyaniline / p-isopropylaniline / p-tert-butylaniline in a molar ratio of 1:(1-1.5) as raw materials, toluene as solvent, tris(dibenzylideneacetone)dipalladium as catalyst, tri-tert-butylphosphine as ligand, and sodium tert-butoxide / potassium tert-butoxide as base to obtain the first intermediate;

[0020] (2) Under inert gas protection, a second substitution reaction is carried out at 100-150 °C for 4-20 h using 3,5-dibromoaniline and iodobenzene / p-methyliodobenzene / p-tert-butyliodobenzene in a molar ratio of 1:(2-3) as raw materials, N,N-dimethylformamide / toluene / xylene as solvent, cuprous iodide and 1,10-phenanthroline as catalysts, and potassium hydroxide as base to obtain a second intermediate;

[0021] (3) Under inert gas protection, a third substitution reaction is carried out at 120-130 °C for 10-24 h using 1,3-dibromo-5-fluorobenzene and carbazole / 3,6-di-tert-butylcarbazole in a molar ratio of (1-2):1 as raw materials, N,N-dimethylformamide / toluene as solvent, and cesium carbonate as base to obtain a third intermediate;

[0022] (4) Under the protection of inert gas, a fourth substitution reaction is carried out at 70-100 ° C for 8-24 h using a molar ratio of (2-5): 1 of biboronic acid pinacol ester and 1,3-dibromobenzene / the second intermediate obtained in step (2) / the third intermediate obtained in step (3) as raw materials, 1,4-dioxane as solvent, [1,1-bis(diphenylphosphino)ferrocene] palladium dichloride as catalyst, and potassium acetate as base to obtain a fourth intermediate;

[0023] (5) Under the protection of inert gas, using p-bromoiodobenzene and the fourth intermediate obtained in step (4) in a molar ratio of (2-3):1 as raw materials, toluene as solvent, tetrakis(triphenylphosphine)palladium as catalyst, and anhydrous potassium carbonate as base, a fifth substitution is carried out at 100-110 °C for 24-48 hours to obtain a fifth intermediate;

[0024] (6) Under the protection of inert gas, the first intermediate obtained in step (1) and the second intermediate obtained in step (2) / the third intermediate obtained in step (3) / the fifth intermediate obtained in step (5) in a molar ratio of (2-2.5):1 are used as raw materials, toluene is used as a solvent, tris(dibenzylideneacetone)dipalladium / palladium acetate is used as a catalyst, tri-tert-butylphosphine is used as a ligand, sodium tert-butoxide / potassium tert-butoxide is used as a base, and a sixth substitution reaction is carried out at 70-90°C for 8-14 hours to obtain a star-shaped small molecule cross-linked hole transport material.

[0025] Preferably, the potassium hydroxide in step (2) is powdered potassium hydroxide.

[0026] The present invention also provides a method for preparing a hole transport layer film, which is prepared using the star-shaped small molecule cross-linked hole transport material described in the above technical solution as a raw material. The preparation method of the hole transport layer film includes the following steps: coating a solution containing the star-shaped small molecule cross-linked hole transport material on the surface of a substrate, and performing heat treatment in an inert gas or nitrogen environment to obtain a hole transport layer film.

[0027] Preferably, the coating method is spin coating or inkjet printing.

[0028] Preferably, the heat treatment temperature is 120-260° C., and the heat treatment time is 10-60 min.

[0029] The present invention also provides the use of the star-shaped small molecule cross-linked hole transport material described in the above technical solution in an organic electroluminescent device, an organic solar cell or an organic thin film transistor.

[0030] Preferably, the organic electroluminescent device is an OLED device.

[0031] The present invention provides a star-shaped small molecule cross-linked hole transport material. Vinyl groups are introduced into a star-shaped small molecule compound (i.e., the star-shaped small molecule cross-linked hole transport material). During the process of preparing a hole transport layer from the star-shaped small molecule compound using a solution method, the vinyl groups undergo a polymerization reaction to form a three-dimensional cross-linked hole transport network, thereby enabling the hole transport layer to resist erosion by commonly used organic solvents such as aromatic hydrocarbons, alcohols, ethers, ketones, esters, and amides, effectively solving the problem of interlayer miscibility and making the selection of luminescent layer materials and solvents more diverse. At the same time, since the twisted aromatic structure of the star-shaped small molecule compound has a steric hindrance effect, the triplet energy level of the hole transport layer prepared therefrom is effectively increased, thereby playing a role in blocking excitons in the luminescent layer. , thereby improving the performance and life of solution-processed OLED devices; the presence of triarylamine vinyl groups in the hole transport layer structure enables the material to have a higher hole mobility, providing sufficient holes for the light-emitting layer, which is beneficial to reducing the driving voltage of the device and improving the power efficiency of the device; the star-shaped small molecule compound has good solubility in common solvents such as tetrahydrofuran, chloroform, toluene, chlorobenzene, etc., and can form a uniform amorphous hole transport layer film by coating; the star-shaped small molecule hole transport material has excellent stability and solvent resistance after cross-linking, high hole mobility and triplet energy level, so that it has good prospects as a hole transport material in optoelectronic devices, especially organic photoluminescent devices.

[0032] The results of Application Example 3 show that the OLED device prepared using the target compound HTM1 prepared in Example 9 of the present invention as a raw material has good performance, CE max and EQE max The high hole mobility and triplet energy levels of the star-shaped small molecule cross-linked hole transport material enable it to improve the performance of OLED devices, verifying its practicality and commercial feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a DSC curve diagram of the target compound HTM13 prepared in Example 10 of the present invention;

[0034] FIG2 is a DSC curve diagram of the target compound HTM1 prepared in Example 9 of the present invention;

[0035] FIG3 is a UV-visible absorption spectrum of the hole transport layer film prepared in Application Example 1 of the present invention before and after being rinsed and soaked in chlorobenzene for 2 minutes;

[0036] FIG4 is a UV-visible absorption spectrum of the hole transport layer film prepared in Application Example 2 of the present invention before and after being rinsed and soaked in toluene for 2 minutes;

[0037] FIG5 is a current efficiency-brightness curve of the OLED device prepared in Application Example 3 of the present invention;

[0038] FIG6 is an electroluminescence spectrum of the OLED device prepared in Application Example 3 of the present invention. DETAILED DESCRIPTION

[0039] The present invention provides a star-shaped small molecule cross-linked hole transport material having one or more of the chemical structures shown in Formula I or Formula II:

[0040] 、 .

[0041] M1 in Formula I or Formula II is hydrogen, substituted or unsubstituted C 12 ~C 90 aromatic amine groups, substituted or unsubstituted C 12 ~C 90 Any one of the heteroaromatic amine groups.

[0042] M2 in Formula I or Formula II is substituted or unsubstituted C 12 ~C 90 One or more aromatic groups.

[0043] In the present invention, M1 in Formula I or Formula II preferably has one of the following structures:

[0044] (diphenylamine), (4,4'-dimethyldiphenylamine), (4,4'-di-tert-butyldiphenylamino), (4,4'-dimethoxydiphenylamine), (carbazolyl), (3,6-di-tert-butylcarbazole group);

[0045] In the present invention, M2 in Formula I or Formula II preferably has one of the following structures:

[0046] (phenyl), (p-methylphenyl), (p-methoxyphenyl), (p-Isopropylphenyl), (p-tert-butylphenyl), (9,9-dimethylfluorenyl), (naphthyl), (biphenyl).

[0047] In the present invention, the star-shaped small molecule cross-linked hole transport material preferably has one or more chemical structures represented by formulas HTM1 to HTM30:

[0048] ;

[0049] .

[0050] The present invention also provides a method for preparing the star-shaped small molecule cross-linked hole transport material described in the above technical solution, comprising the following steps:

[0051] (1) Under inert gas protection, a first substitution reaction is carried out at 70-90 °C for 6-12 h using p-bromostyrene and aniline / 2-naphthylamine / 2-amino-9,9-dimethylfluorene / 4-aminobiphenyl / p-methylaniline / p-methoxyaniline / p-isopropylaniline / p-tert-butylaniline in a molar ratio of 1:(1-1.5) as raw materials, toluene as solvent, tris(dibenzylideneacetone)dipalladium as catalyst, tri-tert-butylphosphine as ligand, and sodium tert-butoxide / potassium tert-butoxide as base to obtain the first intermediate;

[0052] (2) Under inert gas protection, a second substitution reaction is carried out at 100-150 °C for 4-20 h using 3,5-dibromoaniline and iodobenzene / p-methyliodobenzene / p-tert-butyliodobenzene in a molar ratio of 1:(2-3) as raw materials, N,N-dimethylformamide / toluene / xylene as solvent, cuprous iodide and 1,10-phenanthroline as catalysts, and potassium hydroxide as base to obtain a second intermediate;

[0053] (3) Under inert gas protection, a third substitution reaction is carried out at 120-130 °C for 10-24 h using 1,3-dibromo-5-fluorobenzene and carbazole / 3,6-di-tert-butylcarbazole in a molar ratio of (1-2):1 as raw materials, N,N-dimethylformamide / toluene as solvent, and cesium carbonate as base to obtain a third intermediate;

[0054] (4) Under the protection of inert gas, a fourth substitution reaction is carried out at 70-100 ° C for 8-24 h using a molar ratio of (2-5): 1 of biboronic acid pinacol ester and 1,3-dibromobenzene / the second intermediate obtained in step (2) / the third intermediate obtained in step (3) as raw materials, 1,4-dioxane as solvent, [1,1-bis(diphenylphosphino)ferrocene] palladium dichloride as catalyst, and potassium acetate as base to obtain a fourth intermediate;

[0055] (5) Under the protection of inert gas, using p-bromoiodobenzene and the fourth intermediate obtained in step (4) in a molar ratio of (2-3):1 as raw materials, toluene as solvent, tetrakis(triphenylphosphine)palladium as catalyst, and anhydrous potassium carbonate as base, a fifth substitution is carried out at 100-110 °C for 24-48 hours to obtain a fifth intermediate;

[0056] (6) Under the protection of inert gas, the first intermediate obtained in step (1) and the second intermediate obtained in step (2) / the third intermediate obtained in step (3) / the fifth intermediate obtained in step (5) in a molar ratio of (2-2.5):1 are used as raw materials, toluene is used as a solvent, tris(dibenzylideneacetone)dipalladium / palladium acetate is used as a catalyst, tri-tert-butylphosphine is used as a ligand, sodium tert-butoxide / potassium tert-butoxide is used as a base, and a sixth substitution reaction is carried out at 70-90°C for 8-14 hours to obtain a star-shaped small molecule cross-linked hole transport material.

[0057] In the present invention, unless otherwise specified, the raw materials used are conventional commercial products in the field.

[0058] The present invention also provides a method for preparing a hole transport layer film, which is prepared using the star-shaped small molecule cross-linked hole transport material described in the above technical solution as a raw material. The preparation method of the hole transport layer film includes the following steps: coating a solution containing the star-shaped small molecule cross-linked hole transport material on the surface of a conductive anode, and performing heat treatment in an inert gas or nitrogen environment to obtain a hole transport layer film.

[0059] In the present invention, the conductive anode is preferably an indium tin oxide (ITO) anode, and the coating method is preferably spin coating or inkjet printing.

[0060] In the present invention, the solution containing the star-shaped small molecule cross-linked hole transport material preferably further comprises a mixed solution of other hole transport materials and dopants / P-type small molecule organic semiconductor additives dissolved in toluene / chlorobenzene.

[0061] In the present invention, the heat treatment temperature is preferably 120-260°C, and the heat treatment time is preferably 10-60 minutes. The present invention controls the heat treatment temperature and time within the above ranges to allow the star-shaped small molecule cross-linked hole transport material to undergo a cross-linking reaction, thereby obtaining a hole transport layer film with better overall performance.

[0062] The present invention also provides the use of the star-shaped small molecule cross-linked hole transport material described in the above technical solution in an organic electroluminescent device, an organic solar cell or an organic thin film transistor.

[0063] In the present invention, the organic electroluminescent device is an OLED device.

[0064] In the present invention, the star-shaped small molecule cross-linked hole transport material is preferably applied to an organic electroluminescent device by using the star-shaped small molecule cross-linked hole transport material as a raw material to prepare a hole transport layer or a hole injection layer of the organic electroluminescent device by thermal initiation.

[0065] In the present invention, the method for preparing an OLED device using a star-shaped small molecule cross-linked hole transport material preferably includes the following steps:

[0066] (1) First, spin-coat the PEDOT:PSS solution on the pretreated ITO substrate surface and heat it at 100-140 °C in air for 10-30 min to form a hole injection layer film on the ITO substrate surface;

[0067] Alternatively, a mixed solution is prepared using the star-shaped small molecule cross-linked hole transport material and 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenylborate) (TPFB) / 4-octyloxydiphenyliodonium hexafluoroantimonate (OPPI) / 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4-TCNQ) in a mass ratio of (5-100):1 as solutes and toluene or chlorobenzene as solvent. The mixed solution is then spin-coated on the surface of the pretreated ITO substrate for a second time, and the mixture is heated and annealed at 120-260°C for 10-60 min in an inert gas or nitrogen environment to form a completely cross-linked hole injection layer film on the surface of the ITO substrate;

[0068] (2) mixing the star-shaped small molecule cross-linked hole transport material with toluene / chlorobenzene to obtain a hole transport material solution;

[0069] A third step is to spin-coat the hole transport material solution on the surface of the hole injection layer film or the completely cross-linked hole injection layer film obtained in step (1), and heat-anneal at 120-260° C. for 10-60 min in an inert gas or nitrogen environment to form a hole transport layer film on the surface of the hole injection layer film or the completely cross-linked hole injection layer film;

[0070] (3) Mix the host material and the guest material in a mass ratio of (5-20):1 and dissolve them in toluene / chlorobenzene to obtain a host-guest mixed solution;

[0071] The surface of the hole transport layer film obtained in step (2) is fourthly spin-coated with the host-guest mixed solution, and heated and annealed at 80-110° C. for 10 min in an inert gas or nitrogen environment to form a light-emitting layer on the surface of the hole transport layer film, thereby obtaining a spin-coated ITO substrate;

[0072] (4) The spin-coated ITO substrate obtained in step (3) is placed on a mask and sent into a vacuum evaporation chamber. -4 Under a vacuum degree of Pa, electron transport materials, electron injection materials and metal cathodes were deposited in sequence at rates of 1 Å / s, 0.1 Å / s and 10 Å / s, respectively, to obtain OLED devices.

[0073] In the present invention, the ITO substrate is preferably pretreated before use; the pretreatment includes sequentially performing sputtering, etching, solvent cleaning, and cleaning with an oxygen plasma cleaner. In the present invention, the cleaning time of the oxygen plasma cleaner is preferably 5 to 20 minutes.

[0074] In the present invention, the host material is preferably 4,4',4''-tris(carbazole-9-yl)triphenylamine (TCTA) / 4,4'-bis(9-carbazole)biphenyl (CBP) / 2,6-bis(3-(carbazole-9-yl)phenyl)pyridine (26DCzPPY); the guest material is preferably tris[2-(p-tolyl)pyridine-C2,N)iridium(III) (Ir(mppy)3) / bis(1-phenyl-isoquinoline)(acetylacetonate)iridium(III) (Ir(piq)2(acac)) / bis(4,6-difluoro Phenylpyridine-(C2,N) picolinyl iridium (FIrPic) / 2,6-bis[4-(diphenylamino)phenyl]-9,10-anthracenedione (AQ(PhDPA)2) / 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-N3,N3,N6,N6-tetraphenyl-9H-carbazole-3,6-diamine (DACT-II) / bis[4-(3,6-di-tert-butyl-9H-carbazolyl)phenyl]sulfone (BuCz-DPS); the concentration of the host-guest mixed solution is preferably 5-15 mg / mL. In the present invention, the fourth spin coating speed is preferably 2000-5000 rpm, and the fourth spin coating time is preferably 20-30 s.

[0075] In the present invention, the electron transport material is preferably 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) / 1,3,5-tris[(3-pyridyl)-3-phenyl]benzene (TmPyPb); the electron injection material is preferably LiF / CsF / Yb; and the metal cathode is preferably Al / Au / Ag.

[0076] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. 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.

[0077] Example 1 Synthesis of N-phenyl-4-vinylaniline (first intermediate):

[0078] ;

[0079] A 250 mL two-necked flask was charged with aniline (3.74 mL, 41.00 mmol), p-bromostyrene (4.60 mL, 34.15 mmol), tris(dibenzylideneacetone)dipalladium (0.94 g, 1 mmol), sodium tert-butoxide (9.85 g, 0.10 mol), tri-tert-butylphosphine tetrafluoroborate (0.60 g, 2.05 mmol), and 100 mL of anhydrous toluene. The first substitution reaction was carried out at 80°C under inert gas for 12 h. After completion, the product was washed with saturated brine and extracted three times with ethyl acetate. The solvent was evaporated under reduced pressure and separated by column chromatography (eluent: petroleum ether:ethyl acetate = 100:1, v / v) to obtain a white flaky solid in a yield of 70.9%. Its H NMR spectrum is as follows: 1 H NMR (400 MHz, DMSO-d6) δ 8.27 (s, 1H), 7.33 (d, J = 8.5 Hz, 2H), 7.24 (t, J = 7.9 Hz, 2H), 7.09 (d, J = 7.7 Hz, 2H), 7.03 (d, J = 8.5 Hz, 2H), 6.84 (t, J = 7.3 Hz, 1H), 6.63 (dd, J = 17.6, 10.9 Hz, 1H), 5.61 (d, J = 18.4 Hz, 1H), 5.06 (d, J = 10.9 Hz, 1H). HRMS: APCI-HRMS, found value [M+H] + : 196.1133, calculated value [M]: 195.1042.

[0080] Example 2 Synthesis of 4-methyl-N-(4-vinylphenyl)aniline (first intermediate):

[0081] ;

[0082] A 250 mL two-necked flask was charged with p-methylaniline (4.40 g, 41.00 mmol), p-bromostyrene (4.60 mL, 34.15 mmol), tris(dibenzylideneacetone)dipalladium (0.94 g, 1.00 mmol), sodium tert-butoxide (9.85 g, 0.10 mol), tri-tert-butylphosphine tetrafluoroborate (0.60 g, 2.05 mmol), and 120 mL of anhydrous toluene. The first substitution reaction was carried out at 80°C under inert gas for 10 h. After completion, the product was washed with saturated brine, extracted three times with ethyl acetate, and evaporated under reduced pressure to remove the solvent. Column chromatography (eluent: petroleum ether:ethyl acetate = 60:1, v / v) gave a white powder in a yield of 75.8%. Its H NMR spectrum is as follows: 1 H NMR (400 MHz, DMSO-d6) δ 8.14 (s, 1H), 7.30 (d, J = 8.6 Hz, 2H), 7.06 (d, J = 8.2 Hz, 2H), 6.99 (d, J = 8.4 Hz, 2H), 6.96 (d, J = 8.6 Hz, 2H), 6.60 (dd, J = 17.6, 10.9 Hz, 1H), 5.58 (d, J = 16.6 Hz, 1H), 5.03 (d, J = 11.9 Hz, 1H), 2.23 (s, 3H). HRMS: APCI-HRMS, found value [M+H] + : 210.1289, calculated value [M]: 209.1199.

[0083] Example 3 Synthesis of 4-(tert-butyl)-N-(4-vinylphenyl)aniline (first intermediate):

[0084] ;

[0085] A 250 mL two-necked flask was charged with p-tert-butylaniline (15.93 mL, 0.10 mol), p-bromostyrene (6.90 mL, 51.23 mmol), tris(dibenzylideneacetone)dipalladium (1.41 g, 1.50 mmol), sodium tert-butoxide (14.78 g, 0.15 mol), tri-tert-butylphosphine tetrafluoroborate (0.90 g, 3.08 mmol), and 100 mL of anhydrous toluene. The first substitution reaction was carried out at 80°C under inert gas for 6 h. After completion, the product was washed with saturated brine and extracted three times with ethyl acetate. The solvent was evaporated under reduced pressure and separated by column chromatography (eluent: petroleum ether:ethyl acetate = 80:1, v / v) to obtain a white flaky solid in a 63.9% yield. Its high-resolution mass spectrum: APCI-HRMS, found value [M+H] + : 252.1752, calculated value [M]: 251.1668.

[0086] Example 4 Synthesis of 3,5-dibromo-N,N-diphenylaniline (second intermediate):

[0087]

[0088] A 100 mL two-necked flask was charged with 3,5-dibromoaniline (1.00 g, 3.99 mmol), iodobenzene (1.78 mL, 15.98 mmol), cuprous iodide (0.08 g, 0.40 mmol), potassium hydroxide (0.67 g, 11.96 mmol), 1,10-phenanthroline (0.08 g, 0.40 mmol), and 50 mL of anhydrous toluene. The second substitution reaction was carried out at 110°C under inert gas for 18 h. Upon completion of the reaction, the product was washed with saturated brine, extracted three times with dichloromethane, and the solvent was evaporated under reduced pressure. Separation by column chromatography (eluent: pure petroleum ether) afforded a white solid in 89.6% yield. Its H NMR spectrum is as follows: 1 H NMR (600 MHz, Chloroform-d) δ 7.34 - 7.28 (m, 4H), 7.20 (s, 1H), 7.11 (dd, J = 13.9, 7.5 Hz, 6H), 7.07 (d, J = 1.5 Hz, 2H). High-resolution mass spectrometry: APCI-HRMS, found value [M+H] + : 403.9477, calculated value [M]: 402.9389.

[0089] Example 5 Synthesis of 3,6-di-tert-butyl-9-(3,5-dibromophenyl)-9H-carbazole (third intermediate):

[0090]

[0091] A 100 mL two-necked flask was charged with 1,3-dibromo-5-fluorobenzene (5.08 g, 20.00 mmol), 3,6-di-tert-butylcarbazole (1.40 g, 5.00 mmol), cesium carbonate (1.63 g, 5.00 mmol), and 40 mL of N,N-dimethylformamide. The third substitution reaction was carried out at 150°C under inert gas for 24 h. After monitoring the reaction, 400 mL of deionized water was added, the mixture was filtered, and the residue was extracted with dichloromethane. The solvent was then evaporated under reduced pressure. Column chromatography (eluent: petroleum ether:dichloromethane = 3:1, v / v) afforded a white solid in a 78.6% yield. Its high-resolution mass spectrometry (APCI-HRMS) revealed a found value [M+H] + : 514.0566, calculated value [M]: 513.0486.

[0092] Example 6 Synthesis of 9-(3,5-dibromophenyl)-9H-carbazole (third intermediate):

[0093]

[0094] The synthesis steps were the same as those in Example 5, except that 3,6-di-tert-butylcarbazole was replaced with an equal molar amount of carbazole. A white solid was obtained with a yield of 89.4%. Its high-resolution mass spectrum: APCI-HRMS, found value [M+H] + : 401.9306, calculated value [M]: 400.9233.

[0095] Example 7 Synthesis of 9-(3,5-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-3,6-di-tert-butyl-9H-carbazole (fourth intermediate):

[0096]

[0097] A 100 mL two-necked flask was charged with 3,6-di-tert-butyl-9-(3,5-dibromophenyl)-9H-carbazole (2.57 g, 5.00 mmol, prepared in Example 5), pinacol diboronate (5.08 g, 20.00 mmol), potassium acetate (3.93 g, 40.00 mmol), [1,1-bis(diphenylphosphino)ferrocene]palladium dichloride (0.39 g, 0.53 mmol), and 50 mL of anhydrous 1,4-dioxane. Under inert gas protection, the oil bath was heated to 80 °C and the fourth substitution reaction was carried out for 10 h. After the reaction system was cooled to room temperature, it was washed with saturated brine and extracted three times with dichloromethane. The solvent was evaporated under reduced pressure, and the crude product was separated and purified by column chromatography (eluent: petroleum ether: dichloromethane = 20:1, V / V) to obtain white crystals with a yield of 92%. Its high-resolution mass spectrometry: APCI-HRMS, found value [M+H] + : 608.4088, calculated value [M]: 607.4011.

[0098] Example 8 Synthesis of 3,6-di-tert-butyl-9-(4,4'-dibromo-[1,1'-:3'-,1''-triphenyl]-5'-yl)-9H-carbazole (fifth intermediate):

[0099]

[0100] To a 100 mL two-necked flask were added 9-(3,5-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-3,6-di-tert-butyl-9H-carbazole (1.82 g, 3.00 mmol, prepared in Example 7), p-bromoiodobenzene (2.12 g, 7.50 mmol), anhydrous potassium carbonate (2.49 g, 18.00 mmol), tetrakis(triphenylphosphine)palladium (0.42 g, 0.36 mmol), and 50 mL of toluene. Under inert gas protection, the oil bath was heated to 110°C, and the fifth substitution reaction was carried out for 48 h. After the reaction system was cooled to room temperature, it was washed with saturated brine and extracted three times with dichloromethane. The solvent was evaporated under reduced pressure. The crude product was separated and purified by column chromatography (eluent: pure petroleum ether) to obtain white crystals with a yield of 52.3%. Its high-resolution mass spectrometry: APCI-HRMS, found value [M+H] + : 587.2009, calculated value [M]: 586.1993.

[0101] Example 9 N 1 ,N1 -Diphenyl-N 3 ,N 5 -Di-p-tolyl-N 3 ,N 1 -Synthesis of bis(4-vinylphenyl)benzene-1,3,5-triamine (target compound HTM1):

[0102]

[0103] A 100 mL two-necked flask was charged with 3,5-dibromo-N,N-diphenylaniline (0.82 g, 2.11 mmol, prepared in Example 4), 4-methyl-N-(4-vinylphenyl)aniline (0.92 g, 4.43 mmol, prepared in Example 2), tris(dibenzylideneacetone)dipalladium (0.12 g, 0.13 mmol), sodium tert-butoxide (1.01 g, 10.54 mmol), tri-tert-butylphosphine tetrafluoroborate (0.07 g, 0.25 mmol), and 50 mL of anhydrous toluene. The sixth substitution reaction was carried out at 80°C under inert gas for 12 hours. After completion, the reaction was washed with saturated brine, extracted three times with ethyl acetate, and the solvent was evaporated under reduced pressure. Column chromatography (eluent: petroleum ether:ethyl acetate = 60:1, v / v) afforded the target compound HTM1 as a white powder in a 76.2% yield. Its NMR spectrum information is as follows: 1 H NMR (400 MHz, DMSO-d6) δ 7.28 (d, J = 8.4 Hz, 4H), 7.22 (t, J = 7.7 Hz, 4H), 7.05 (d, J = 8.1 Hz, 4H), 7.01 - 6.94 (m, 5H), 6.94 - 6.83 (m, 8H), 6.60 (dd, J = 17.6, 11.0 Hz, 3H), 6.12 (d, J = 12.5 Hz, 3H), 5.65 (d, J = 17.5 Hz, 2H), 5.13 (d, J = 11.0 Hz, 2H), 2.21 (s, 6H). 13C NMR (151 MHz, Chloroform-d) δ 148.93, 147.35, 147.17, 144.47, 136.40, 132.90, 131.33, 129.85, 129.07, 126.87, 124.85, 123.90, 122.79, 122.57, 114.42, 111.77, 20.88. High-resolution mass spectrum of HTM2: APCI-HRMS, found value [M+H] + : 660.3362, calculated value [M]: 659.3295.

[0104] The crosslinking temperature (T c ) range, and the DSC curve of the target compound HTM1 prepared in Example 9 of the present invention was obtained, as shown in Figure 2. As shown in Figure 2, the first heating scan curve has a clear exothermic peak at 210°C, corresponding to the cross-linking process of the target compound HTM1. The second heating scan curve does not show any obvious endothermic or exothermic peaks, indicating that the cross-linking reaction of compound HTM1 was complete in the first heating. The results of the two heating scan curves show that HTM1 has good thermal properties. After complete cross-linking, no other endothermic or exothermic phenomena occur, which is conducive to the long life and high stability of devices prepared from it.

[0105] Application Example 1

[0106] The preparation method of the hole transport layer thin film is prepared by using the star-shaped small molecule cross-linked hole transport material prepared in Example 9, namely the target compound HTM1, as a raw material, and the steps are as follows:

[0107] The star-shaped small molecule cross-linked hole transport material prepared in Example 9, namely the target compound HTM1, was dissolved in toluene to prepare a toluene solution containing the star-shaped small molecule cross-linked hole transport material at a concentration of 6 mg / mL;

[0108] A toluene solution containing the star-shaped small molecule cross-linked hole transport material at a concentration of 6 mg / mL was spin-coated on the surface of a quartz substrate, and heat-treated at 220° C. for 30 min in a nitrogen atmosphere to obtain a hole transport layer film.

[0109] The optical band gap and characteristic absorption peak of the material can be determined by using a UV-visible spectrophotometer. The change in the maximum absorption peak (ABS) of the UV-visible absorption (UV-vis) spectrum before and after washing with toluene indicates the solvent resistance of the cross-linked film, and indirectly indicates its cross-linking degree CD=ABS. 后 ABS 前FIG3 shows the UV-visible absorption spectra of the hole transport layer film prepared in Application Example 1 of the present invention before and after being rinsed and soaked in chlorobenzene for 2 minutes. As shown in FIG3 , the intensity of the maximum absorption peak of the UV-visible absorption spectrum of the cross-linked hole transport layer film after being rinsed and soaked in chlorobenzene for 2 minutes does not decrease significantly. The film has excellent solvent resistance and can be used to solve the problem of interlayer solubility.

[0110] Example 10 5-(9H-carbazol-9-yl)-N 1 ,N 3 -Di-p-tolyl-N 1 ,N 3 -Synthesis of di(4-vinylphenyl)benzene-1,3-diamine (target compound HTM13):

[0111]

[0112] A 100 mL two-necked flask was charged with 9-(3,5-dibromophenyl)-9H-carbazole (0.90 g, 2.18 mmol, prepared in Example 6), 4-methyl-N-(4-vinylphenyl)aniline (0.91 g, 4.35 mmol, prepared in Example 2), tris(dibenzylideneacetone)dipalladium (0.12 g, 0.13 mmol), sodium tert-butoxide (1.05 g, 10.88 mmol), tri-tert-butylphosphine tetrafluoroborate (0.08 g, 0.26 mmol), and 70 mL of anhydrous toluene. The sixth substitution reaction was carried out at 80°C under inert gas for 11 hours. After completion of the reaction, the product was washed with saturated brine, extracted three times with ethyl acetate, and the solvent was evaporated under reduced pressure. Column chromatography (eluent: petroleum ether:ethyl acetate = 60:1, v / v) yielded the target compound HTM13 as a white powder in 74.7% yield. Its NMR spectrum is as follows: 1 H NMR (600 MHz, DMSO-d6) δ 8.11 (d, J = 7.7 Hz, 2H), 7.36 - 7.31 (m, 8H), 7.18 (dt, J = 8.0, 4.3 Hz, 2H), 7.09 (d, J = 8.1 Hz, 4H), 7.03 (d, J = 8.2 Hz, 8H), 6.58 (dd, J = 18.2, 11.5 Hz, 3H), 6.47 (s, 2H), 5.64 (d, J = 17.6 Hz, 2H), 5.11 (d, J = 11.0 Hz, 2H), 2.18 (s, 6H). 13C NMR (151 MHz, Chloroform-d) δ 149.65, 146.94, 144.37, 140.39, 139.01, 136.29, 133.70, 132.24, 130.16, 127.13, 125.83, 125.42, 123.70, 123.38, 120.27, 119.86, 115.74, 114.55, 112.36, 110.14, 20.94. High-resolution mass spectrum of HTM14: APCI-HRMS, found value [M+H] + : 658.3215, calculated value [M]: 657.3138.

[0113] Using DSC testing, the DSC curve of the target compound HTM13 prepared in Example 10 of the present invention is shown in FIG1 . As shown in FIG1 , the cross-linking reaction of the target compound HTM13 occurs at around 180° C.

[0114] Application Example 2

[0115] A hole transport layer film was prepared according to the method of Application Example 1, except that the target compound HTM13 prepared in Example 10 was used as a raw material.

[0116] Using an ultraviolet-visible spectrophotometer, the ultraviolet-visible absorption spectra of the hole transport layer film prepared in Application Example 2 of the present invention before and after being rinsed and soaked in toluene for 2 minutes are detected, as shown in Figure 4. As can be seen from Figure 4, after the hole transport layer film prepared in Application Example 2 is rinsed and soaked in toluene for 2 minutes, the intensity of the maximum absorption peak of its ultraviolet-visible absorption spectrum does not decrease significantly, and the film has excellent solvent resistance.

[0117] Example 11 N 4 ,N 4’’ -bis(4-(tert-butyl)phenyl)-5'-(3,6-di-tert-butyl-9H-carbazol-9-yl)-N 4 ,N 4’’ -Synthesis of bis(4-vinylphenyl)-[1,1':3',1''-triphenyl]-4,4'-diamine (target compound HTM22):

[0118]

[0119] The synthesis steps were the same as those in Example 10, except that 3,6-di-tert-butyl-9-(3,5-dibromophenyl)-9H-carbazole was replaced with an equal amount of 3,6-di-tert-butyl-9-(4,4'-dibromo-[1,1':3',1''-triphenyl]-5'-yl)-9H-carbazole (prepared in Example 8), and 4-methyl-N-(4-vinylphenyl)aniline was replaced with an equal amount of 4-(tert-butyl)-N-(4-vinylphenyl)aniline (prepared in Example 3). The target compound HTM22 was obtained as a white solid in a 65.9% yield. Its high-resolution mass spectrum: APCI-HRMS, found value [M+H] + : 1006.6023, calculated value [M]: 1005.5955.

[0120] Application Example 3

[0121] The preparation method (solution method) of an OLED device using the target compound HTM1 prepared in Example 9, i.e., a star-shaped small molecule cross-linked hole transport material, as a raw material is as follows:

[0122] (1) ITO was first sputtered on a glass substrate as a conductive anode, and the ITO anode substrate was etched. The etched ITO glass substrate was then ultrasonically cleaned with a cleaning agent, deionized water, deionized water, anhydrous ethanol, and anhydrous ethanol for 30 min each. The solvent on the surface of the ITO glass was blown away with a nitrogen flow. Subsequently, the dried ITO glass was cleaned with an oxygen plasma cleaner for 10 min to obtain a pretreated ITO substrate.

[0123] The PEDOT:PSS 4083 solution was filtered through a disposable syringe filter, and 40 μL of the filtered PEDOT:PSS 4083 solution was spin-coated on the pretreated ITO substrate at a speed of 4000 r / min for 30 s. The substrate was then transferred to a hot plate at 140 °C and annealed for 15 min to form a hole injection layer film on the pretreated ITO substrate surface.

[0124] (2) The target compound HTM1 prepared in step 9 was dissolved in toluene to prepare a mixed solution of 6 mg / mL, 40 μL of the mixed solution was spin-coated on the surface of the hole injection layer film obtained in step (1), and the solution was coated at a high speed of 4000 r / min for 30 s. The solution was then placed on a hot plate in a nitrogen atmosphere, and the temperature of the hot plate was raised to 220 °C for annealing for 30 min to form a hole transport layer film on the surface of the hole injection layer film.

[0125] (3) The host material TCTA was dissolved in toluene to prepare a 9 mg / mL host material toluene solution, 1 mL of the host material toluene solution was added to 1 mg of the guest material Ir(mppy)3, and ultrasonically mixed to form a host-guest mixed solution containing a mass ratio of the host material to the guest material of 9:1; 40 μL of the host-guest mixed solution was spin-coated on the surface of the hole transport layer film obtained in step (2) at a speed of 3000 r / min for 30 s, and heated and annealed at 80 °C for 10 min in a nitrogen atmosphere to remove the solvent, forming a light-emitting layer on the surface of the hole transport layer film to obtain an ITO substrate after spin coating;

[0126] (4) The spin-coated ITO substrate obtained in step (3) is placed on a mask and sent into a vacuum evaporation chamber. -4 Pa, 55nm TPBi, 1nm LiF and 100nm Al were deposited in sequence at rates of 1 Å / s, 0.1 Å / s and 10 Å / s, respectively, to obtain OLED devices.

[0127] The current density-voltage (JV) curve of the device was measured using a Keithley 2400 digital source meter, and the brightness (L) of the device was measured using a silicon photodiode. The current efficiency-brightness curve of the OLED device prepared using the target compound HTM1 prepared in Example 9 of the present invention as a raw material (i.e., prepared in Application Example 3) is shown in FIG5 . As can be seen from FIG5 , the maximum current efficiency (CE) of the OLED device prepared using the target compound HTM1 prepared in Example 9 of the present invention as a raw material is max ) is 63.88 cd / A.

[0128] The electroluminescence spectrum and color coordinates of the OLED device prepared in Application Example 3 were measured using a Konica Minolta CS-2000 spectroradiometer. The electroluminescence spectrum of the OLED device prepared using the target compound HTM1 prepared in Example 9 of the present invention as a raw material is shown in FIG6 . As can be seen from FIG6 , the peak of the electroluminescence spectrum is at 515 nm, which is the characteristic peak of Ir(mppy) 3 , indicating that the hole and electron recombination area is in the light-emitting layer.

[0129] In summary, the cross-linked film prepared using the target compound HTM1 prepared in Example 9 of the present invention as a raw material has a HOMO energy level that matches the luminescent layer, effectively reducing the hole injection barrier; at the same time, it has a triplet energy level higher than that of the luminescent material, effectively blocking the migration of excitons in the luminescent layer. The OLED device prepared using the target compound HTM1 prepared in Example 9 of the present invention as a raw material has good performance, CE max and EQE maxThe results are 63.88 cd / A and 18.33%, respectively. This invention introduces vinyl groups into star-shaped small molecule compounds, enabling polymerization to form a three-dimensional cross-linked network polymer with excellent stability and solvent resistance. This solves the problem of hole transport performance degradation caused by the easy crystallization of small molecule hole transport materials. It also effectively addresses the interlayer miscibility issues encountered in the solution-based preparation of optoelectronic devices, allowing for a wider selection of materials and solvents for the light-emitting layer and enhancing device stability. Furthermore, the twisted aromatic structure of the star-shaped small molecule compound exhibits a steric hindrance effect, effectively increasing the triplet energy level of the cross-linked hole transport layer prepared from it, thereby blocking excitons in the light-emitting layer and improving the performance of organic photoluminescent devices. This demonstrates its practicality and commercial feasibility, and shows promising prospects as a hole transport material in optoelectronic devices, especially organic photoluminescent devices.

[0130] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A star-shaped small molecule cross-linked hole transport material having one or more of the chemical structures shown in Formula I or Formula II: ； M1 in Formula I or Formula II has one of the following structures: ； M2 in Formula I or Formula II is one of the following structures: 。 2. The star-shaped small molecule cross-linked hole transport material according to claim 1, characterized in that: The star-shaped small molecule cross-linked hole transport material has one or more chemical structures shown in formulas HTM1 to HTM22: ； 。 3. The method for preparing the star-shaped small molecule cross-linked hole transport material according to claim 1 or 2, comprising the following steps: (1) Under the protection of inert gas, a first substitution reaction is carried out at 70-90°C for 6-12 h using p-bromostyrene and aniline / 2-naphthylamine / 2-amino-9,9-dimethylfluorene / 4-aminobiphenyl / p-methylaniline / p-methoxyaniline / p-isopropylaniline / p-tert-butylaniline in a molar ratio of 1:(1-1.5) as raw materials, toluene as solvent, tri(dibenzylideneacetone)dipalladium as catalyst, tri-tert-butylphosphine as ligand, sodium tert-butoxide / potassium tert-butoxide as base, to obtain a first intermediate; (2) Under the protection of inert gas, 3,5-dibromoaniline and iodobenzene / p-methyl iodobenzene / p-tert-butyl iodobenzene in a molar ratio of 1:(2-3) are used as raw materials, N,N-dimethylformamide / toluene / xylene is used as solvent, cuprous iodide and 1,10-phenanthroline are used as catalysts, potassium hydroxide is used as base, and a second substitution reaction is carried out at 100-150 °C for 4-20 h to obtain a second intermediate; (3) Under the protection of inert gas, 1,3-dibromo-5-fluorobenzene and carbazole / 3,6-di-tert-butylcarbazole in a molar ratio of (1-2):1 are used as raw materials, N,N-dimethylformamide / toluene is used as solvent, cesium carbonate is used as base, and a third substitution reaction is carried out at 120-130 °C for 10-24 h to obtain a third intermediate; (4) Under the protection of inert gas, using a molar ratio of (2-5):1 of biboric acid pinacol ester and 1,3-dibromobenzene / the second intermediate obtained in step (2) / the third intermediate obtained in step (3) as raw materials, 1,4-dioxane as solvent, [1,1-bis(diphenylphosphino)ferrocene]palladium dichloride as catalyst, potassium acetate as base, and performing a fourth substitution reaction at 70-100° C. for 8-24 h to obtain a fourth intermediate; (5) Under the protection of inert gas, using p-bromoiodobenzene and the fourth intermediate obtained in step (4) in a molar ratio of (2-3):1 as raw materials, toluene as solvent, tetrakis(triphenylphosphine)palladium as catalyst, and anhydrous potassium carbonate as base, and performing a fifth substitution at 100-110° C. for 24-48 h to obtain a fifth intermediate; (6) Under the protection of inert gas, the first intermediate obtained in step (1) and the second intermediate obtained in step (2) / the third intermediate obtained in step (3) / the fifth intermediate obtained in step (5) in a molar ratio of (2-2.5):1 are used as raw materials, toluene is used as a solvent, tri(dibenzylideneacetone)dipalladium / palladium acetate is used as a catalyst, tri-tert-butylphosphine is used as a ligand, sodium tert-butoxide / potassium tert-butoxide is used as a base, and a sixth substitution reaction is carried out at 70-90° C. for 8-14 h to obtain a star-shaped small molecule cross-linked hole transport material.

4. The preparation method according to claim 3, characterized in that: The potassium hydroxide in step (2) is powdered potassium hydroxide.

5. A method for preparing a hole transport layer film, which is prepared using the star-shaped small molecule cross-linked hole transport material as described in claim 1 or 2 as a raw material. The method for preparing the hole transport layer film comprises the following steps: coating a solution containing the star-shaped small molecule cross-linked hole transport material on the surface of a substrate, and performing heat treatment in an inert gas or nitrogen environment to obtain a hole transport layer film.

6. The preparation method according to claim 5, characterized in that: The coating method is spin coating or inkjet printing.

7. The preparation method according to claim 5, characterized in that: The temperature of the heat treatment is 120-260° C., and the time of the heat treatment is 10-60 min.

8. Use of the star-shaped small molecule cross-linked hole transport material according to claim 1 or 2 in an organic electroluminescent device, an organic solar cell or an organic thin film transistor.

9. The use according to claim 8, characterized in that: The organic electroluminescent device is an OLED device.

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