Hole transport material based on thieno [3, 2-b] indole and synthesis method thereof

Abstract

The invention discloses a hole transport material based on thieno [3, 2-b] indole and a synthesis method thereof. A central core molecule thieno [3, 2-b] indole core is used as a module to be applied to the perovskite solar cell hole transport material, different carbon branched chains, methoxyaniline and 4-methoxy-N-(4-methoxyphenyl)-N-phenylaniline are introduced, and the introduction of different groups can effectively improve the energy level and hole mobility of molecules, so that the hole transport material can be applied to the perovskite solar cell hole transport material. Therefore, the material can have better hole transport capacity, the performance of a device is improved, the photoelectric conversion efficiency is improved, and the stability of the device is improved.

Description

Technical Field

[0001] The invention belongs to the field of perovskite solar cells and relates to a hole transport material based on thieno[3,2-b]indole and a synthesis method thereof. Background Art

[0002] Organic perovskite solar cells (PSCs) are an important research hotspot for next-generation photovoltaics due to their unique optical and electrical properties. In just a few years, the power conversion efficiency (PCE) of PSCs has been significantly improved from 3.8% to over 25.7%. Despite the improvement in PCE, the commercialization of such PSCs has been hampered by their limited device stability.

[0003] Typically, the best performing conventional PSCs consist of an electron selective layer, an n-type mesoporous metal oxide scaffold, a perovskite layer, a p-type hole transport material (HTM), and a metal electrode. The performance of small molecule HTMs is closely related to the structure of the central core, which significantly affects the hole carrier mobility of the HTM layer. Notably, strong intermolecular p–p stacking has been shown to be key to improving hole carrier mobility. Studies have shown that electron-rich fused heterocycles, such as carbazole, not only facilitate p–p stacking but also facilitate hole extraction.

[0004] Thieno[3,2-b]indole has a p–p stacking structure as its central core, and due to its strong electron-donating ability and coplanarity, it is beneficial for hole extraction in perovskite solar cells. At present, thieno[3,2-b]indole is mainly used in dye-sensitized solar cells (DSSCs) and mesoporous titanium dioxide thin film sensitizers, and is also used as a structural branch in solar cells. However, its thermal stability is low, and its material decomposition temperature is only 300-350°C (Zhou X, Lu J, Huang H, et al. Thieno[3,2-b]indole(TI)bridged A-π-D-π-Asmall molecules:Synthesis,characterizations and organic solar cell applications[J].Dyes and Pigments,2018,160.). Therefore, the development and design of hole transport layer materials with high hole mobility, low cost and strong stability based on thieno[3,2-b]indole is of great significance for promoting the basic research and commercial application of perovskite solar cells. Summary of the invention

[0005] The object of the present invention is to provide a hole transport material based on thieno[3,2-b]indole and a synthesis method thereof. The hole transport material has high thermal stability and can be used in perovskite solar cells.

[0006] The technical solution for achieving the purpose of the present invention is as follows:

[0007] Thieno[3,2-b]indole-based hole transport material with the structural formula:

[0008]

[0009]

[0010]

[0011]

[0012] The synthesis method of hole transport material based on thieno[3,2-b]indole comprises the following steps:

[0013] (1) Under nitrogen protection, 1,4-dibromo-2-nitrobenzene and 2-tributylstannylthiophene undergo Still coupling reaction at 100-110°C under the catalysis of tetrakistriphenylphosphine palladium (Pd(PPh3)4) to generate 2-(4-bromo-2-nitrophenyl)thiophene.

[0014]

[0015] (2) Using chlorobenzene as solvent, 2-(4-bromo-2-nitrophenyl)thiophene reacts with triphenylphosphine (PPh3) at 135-145°C to generate 6-bromo-4H-thieno[3,2-b]indole.

[0016]

[0017] (3) Using N,N-dimethylformamide (DMF) as solvent, 6-bromo-4H-thieno[3,2-b]indole and isooctane bromide react at 35-45°C under the action of sodium hydride to generate 6-bromo-4-(2-ethylhexyl)-4H-thieno[3,2-b]indole.

[0018]

[0019] Or, using DMF as solvent, 6-bromo-4H-thieno[3,2-b]indole and dodecyl bromide react at 35-45°C under the action of sodium hydride to generate 6-bromo-4-dodecyl-4H-thieno[3,2-b]indole.

[0020]

[0021] Alternatively, in ethylene glycol dimethyl ether (DME) and potassium hydroxide aqueous solution, 6-bromo-4H-thieno[3,2-b]indole reacts with p-iodoanisole, cuprous iodide and 1,10-phenanthroline at 90-95°C to generate 6-bromo-4-(4-methoxyphenyl)-4H-thieno[3,2-b]indole.

[0022]

[0023] Or in DME and potassium hydroxide aqueous solution, 6-bromo-4H-thieno[3,2-b]indole, 4-iodo-N,N-bis(4-methoxyphenyl)aniline, cuprous iodide and 1,10-phenanthroline react at 90-95°C to generate 4-(6-bromo-4H-thieno[3,2-b]indol-4-yl)-N,N-bis(4-methoxyphenyl)aniline.

[0024]

[0025] (4) using tetrahydrofuran as solvent, the product in step (3) and N-bromosuccinimide react at 0° C. to generate an intermediate,

[0026]

[0027]

[0028] (5) In the presence of tetrahydrofuran and sodium carbonate aqueous solution, the intermediate and 4-boric acid ester-4',4'-dimethoxytriphenylamine are reacted at 75-80° C. under the catalysis of tetrakistriphenylphosphine palladium to generate the target product.

[0029]

[0030] Furthermore, in step (1), the molar ratio of 4-dibromo-2-nitrobenzene to 2-tributylstannylthiophene is 1:0.9.

[0031] Furthermore, in step (2), the molar ratio of 2-(4-bromo-2-nitrophenyl)thiophene to triphenylphosphine is 1:5.

[0032] Furthermore, in step (3), the volume ratio of ethylene glycol dimethyl ether to water is 1:2.

[0033] Furthermore, in step (5), the volume ratio of tetrahydrofuran to water is 1:1.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The synthesis method of the present invention is simple, and the synthesized compound based on thieno[3,2-b]indole nucleus and 4-methoxy-N-(4-methoxyphenyl)-N-phenylaniline as the end group has a higher glass transition temperature (90-100°C), higher thermal stability, higher thermal decomposition temperature (400-450°C), and higher HOMO energy level (-5.11-5.00 eV). It is used as a calcium hole transport material in perovskite solar cells, which can improve the hole transport mobility in the solar cell, thereby improving the device stability;

[0036] (2) The present invention applies the central core molecule thieno[3,2-b]indole core as a module in the hole transport material of perovskite solar cells, introduces different carbon side chains, methoxyaniline and 4-methoxy-N-(4-methoxyphenyl)-N-phenylaniline. The introduction of different groups can effectively improve the energy level and hole mobility of the molecule, so that the material can have better hole transport ability, improve device performance, increase photoelectric conversion efficiency, and improve device stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Cyclic voltammetry curves of BPTPA-C12 (a), BPTPA-C2C6 (b), BPTPA-PhOMe (c), and BPT-3TPA (d) materials.

[0038] Figure 2 UV-visible absorption spectra of BPTPA-C12, BPTPA-C2C6, BPTPA-PhOMe, and BPT-3TPA material solutions (a) and after coating (b).

[0039] Figure 3 These are the thermogravimetric analysis curves of BPTPA-C12, BPTPA-C2C6, BPTPA-PhOMe, and BPT-3TPA materials.

[0040] Figure 4 These are the differential scanning calorimetry curves of BPTPA-C12, BPTPA-C2C6, BPTPA-PhOMe, and BPT-3TPA materials. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in conjunction with specific embodiments and accompanying drawings.

[0042] In the following examples, the structure of the final product was determined by nuclear magnetic resonance, the optical properties of the material were determined by ultraviolet-visible absorption spectroscopy, the electrochemical properties of the material were characterized by cyclic voltammetry, and the stability of the material was characterized by thermogravimetric analysis and differential scanning calorimetry.

[0043] Example 1: Synthesis of 4,4'-(4-dodecyl-4H-thieno[3,2-b]indole-2,6-diyl)bis(N,N-bis(4-methoxyphenyl)aniline) (BPTPA-C12):

[0044] (1) Under nitrogen protection, 1,4-dibromo-2-nitrobenzene and 2-tributylstannylthiophene undergo Still coupling reaction at 110°C under the catalysis of Pd(PPh3)4 to generate 2-(4-bromo-2-nitrophenyl)thiophene.

[0045]

[0046] (2) Using chlorobenzene as solvent, 2-(4-bromo-2-nitrophenyl)thiophene reacts with PPh3 at 140°C to generate 6-bromo-4H-thieno[3,2-b]indole (BPT-BR).

[0047]

[0048] (3) Synthesis of compound 6-bromo-4-dodecyl-4H-thiophene[3,2-b]indole (BPT-C12-BR):

[0049]

[0050] NaH (2.86 g, 71 mmol) was slowly added to a solution of BPT-BR (1.8 g, 7.14 mmol) dissolved in anhydrous DMF (30 mL), and the reaction mixture was stirred at 40 ° C under argon for 40 min. To the solution was added isooctane bromide (1.78 g, 7.14 mmol), and the reaction mixture was stirred at 40 ° C under a nitrogen atmosphere for 4 h. The resulting mixture was quenched with distilled water (3 mL) and then extracted with dichloromethane (300 mL). The crude product was dried over anhydrous magnesium sulfate. It was distilled under reduced pressure and purified by silica gel column chromatography to obtain BPT-C12-BR with a yield of 82%.

[0051] (4) Synthesis of compound 2,6-dibromo-4-dodecyl-4H-thiophene[3,2-b]indole (BPT-C12-2BR):

[0052]

[0053] NBS (1.69 g, 9.51 mmol) was slowly added in batches to a solution of BPT-C12-BR (2 g, 4.76 mmol) in tetrahydrofuran as solvent at 0°C, and the mixture was stirred at room temperature overnight. The reaction mixture was quenched with water (30 mL) and then extracted with ethyl acetate (300 mL). The crude product was dried over anhydrous magnesium sulfate. It was distilled under reduced pressure and purified by silica gel column chromatography to obtain BPT-C12-2BRr with a yield of 89%.

[0054] (5) Synthesis of the compound 4,4'-(4-dodecyl-4H-thieno[3,2-b]indole-2,6-diyl)bis(N,N-bis(4-methoxyphenyl)aniline) (BPTPA-C12):

[0055]

[0056] BPT-C12-2BR (0.8 g, 1.6 mmol), OMETPA-BPIN (3.46 g, 8.01 mmol), Pd(PPh3)4 (0.2 g, 0.17 mmol) and tetrahydrofuran solvent (35 mL) were added to a round-bottom flask, and then an aqueous sodium carbonate solution (4.43 g, 2 M) was added. The reaction was refluxed under nitrogen for 12 hours. The resulting mixture was quenched with distilled water (3 mL) and then extracted with ethyl acetate (300 mL). The crude product was dried over anhydrous magnesium sulfate. It was distilled under reduced pressure and purified by silica gel column chromatography to obtain BPTPA-C12 with a yield of 78%. 1 H NMR(500MHz,Methylene Chloride-d2)δ7.61–6.80(m,30H),4.28(t,J=7.2Hz,2H),3.80(s,12H),1.89(t,J=7.3Hz,2H),1.39–1.31(m,4H),1.22(s,15H),0.85(s,2H).

[0057] Example 2: Synthesis of 4,4'-(4-(2-ethylhexyl)-4H-thieno[3,2-b]indole-2,6-diyl)bis(N,N-bis(4-methoxyphenyl)aniline) (BPTPA-C2C6):

[0058] (1) Under nitrogen protection, 1,4-dibromo-2-nitrobenzene and 2-tributylstannylthiophene undergo Still coupling reaction at 110°C under the catalysis of Pd(PPh3)4 to generate 2-(4-bromo-2-nitrophenyl)thiophene.

[0059]

[0060] (2) Using chlorobenzene as solvent, 2-(4-bromo-2-nitrophenyl)thiophene reacts with PPh3 at 140°C to generate 6-bromo-4H-thieno[3,2-b]indole (BPT-BR).

[0061]

[0062] (3) Synthesis of compound 6-bromo-4-(2-ethylhexyl)-4H-thieno[3,2-b]indole (BPT-C2C6-BR):

[0063]

[0064] NaH (2.7 g, 67 mmol) was slowly added to a solution of BPT-BR (1.7 g, 6.7 mmol) dissolved in anhydrous DMF (30 mL), and the reaction mixture was stirred at 40 ° C under argon for 40 min. To the solution was added isooctane bromide (1.3 g, 6.7 mmol), and the reaction mixture was stirred at 40 ° C under a nitrogen atmosphere for 4 h. The resulting mixture was quenched with distilled water (3 mL) and then extracted with dichloromethane (300 mL). The crude product was dried over anhydrous magnesium sulfate. It was distilled under reduced pressure and purified by silica gel column chromatography to obtain BPT-C2C6-BR with a yield of 82%.

[0065] (4) Synthesis of compound 2,6-dibromo-4-(2-ethylhexyl)-4H-thieno[3,2-b]indole (BPT-C2C6-2BR):

[0066]

[0067] NBS (0.88 g, 4.94 mmol) was slowly added in batches to a solution of BPT-C2C6-BR (0.9 g, 2.47 mmol) in tetrahydrofuran as solvent at 0°C, and the mixture was stirred at room temperature overnight. The reaction mixture was quenched with water (30 mL) and then extracted with ethyl acetate (300 mL). The crude product was dried over anhydrous magnesium sulfate. It was distilled under reduced pressure and purified by silica gel column chromatography to obtain BPT-C2C6-2BRr with a yield of 90%.

[0068] (5) Synthesis of the compound 4,4'-(4-(2-ethylhexyl)-4H-thieno[3,2-b]indole-2,6-diyl)bis(N,N-bis(4-methoxyphenyl)aniline) (BPTPA-C2C6):

[0069]

[0070] BPT-C2C6-2BR (0.36 g, 0.8 mmol), OMETPA-BPIN (1.75 g, 4.06 mmol), Pd(PPh3)4 (0.2 g, 0.17 mmol) and tetrahydrofuran solvent (35 mL) were added to a round-bottom flask, and then an aqueous sodium carbonate solution (0.72 g, 2 M) was added. The reaction was refluxed under nitrogen for 12 hours. The resulting mixture was quenched with distilled water (3 mL) and then extracted with ethyl acetate (300 mL). The crude product was dried over anhydrous magnesium sulfate. It was distilled under reduced pressure and purified by silica gel column chromatography to obtain BPTPA-C2C6 with a yield of 79%. 1 H NMR (500MHz, CD2Cl2, δ): 7.64–6.60 (m, 28H), 4.16 (t, J = 7.7Hz, 2H), 3.80 (s, 12H), 2.10–2.04 ( m,1H),1.43–1.33(m,4H),1.27(d,J=4.5Hz,4H),0.92(t,J=7.4Hz,3H),0.85(t,J=7.1Hz,3H).

[0071] Example 3: Synthesis of 4,4'-(4-(4-methoxyphenyl)-4H-thieno[3,2-b]indole-2,6-diyl)bis(N,N-bis(4-methylphenyl)aniline) (BPTPA-PhOMe):

[0072] (1) Under nitrogen protection, 1,4-dibromo-2-nitrobenzene and 2-tributylstannylthiophene undergo Still coupling reaction at 110°C under the catalysis of Pd(PPh3)4 to generate 2-(4-bromo-2-nitrophenyl)thiophene.

[0073]

[0074] (2) Using chlorobenzene as solvent, 2-(4-bromo-2-nitrophenyl)thiophene reacts with PPh3 at 140°C to generate 6-bromo-4H-thieno[3,2-b]indole (BPT-BR).

[0075]

[0076] (3) Synthesis of compound 6-bromo-4-(4-methoxyphenyl)-4H-thieno[3,2-b]indole (BPTPA-PhOMe-BR):

[0077]

[0078] BPT-BR (2.14 g, 8.49 mmol), p-iodoanisole (19.86 g, 84.88 mmol), CuI (1.3 g, 6.79 mmol), 1,10-phenanthroline (3.06 g, 16.98 mmol) and ethylene glycol dimethyl ether solvent (35 mL) were added to a round-bottom flask, and then potassium hydroxide aqueous solution (4.76 g, 85 mmol) was added. The reaction was refluxed under nitrogen for 24 hours. The resulting mixture was quenched with distilled water (3 mL) and then extracted with dichloromethane (300 mL). The crude product was dried over anhydrous magnesium sulfate. It was distilled under reduced pressure and purified by silica gel column chromatography to obtain BPTPA-PhOMe-BR with a yield of 83%.

[0079] (4) Synthesis of 2,6-dibromo-4-(4-methoxyphenyl)-4H-thieno[3,2-b]indole (BPTPA-PhOMe-2BR):

[0080]

[0081] NBS (0.79 g, 4.47 mmol) was slowly added in batches to a solution of BPT-PhOMe-BR (0.8 g, 2.23 mmol) in tetrahydrofuran as solvent at 0°C, and the mixture was stirred at room temperature overnight. The reaction mixture was quenched with water (30 mL) and then extracted with ethyl acetate (300 mL). The crude product was dried over anhydrous magnesium sulfate. BPT-PhOMe-2BRr was obtained by distillation under reduced pressure and purification by silica gel column chromatography with a yield of 89%.

[0082] (5) Synthesis of the compound 4,4'-(4-(4-methoxyphenyl)-4H-thieno[3,2-b]indole-2,6-diyl)bis(N,N-bis(4-methylphenyl)aniline) (BPTPA-PhOMe):

[0083]

[0084] BPT-PhOMe-2BR (0.78 g, 1.78 mmol), OMETPA-BPIN (3.85 g, 8.92 mmol), Pd(PPh3)4 (0.04 g, 0.035 mmol) and tetrahydrofuran solvent (35 mL) were added to a round-bottom flask, and then an aqueous sodium carbonate solution (3.78 g, 2 M) was added. The reaction was refluxed under nitrogen for 12 hours. The resulting mixture was quenched with distilled water (3 mL) and then extracted with ethyl acetate (300 mL). The crude product was dried over anhydrous magnesium sulfate. It was distilled under reduced pressure and purified by silica gel column chromatography to obtain BPTPA-PhOMe with a yield of 80%. 1H NMR (500MHz, CD2Cl2, δ): 7.57–6.83 (m, 32H), 3.89 (s, 6H), 3.79 (s, 6H), 1.28 (d, J = 15.5Hz, 3H).

[0085] Example 4: Synthesis of 4,4',4'-(4H-thieno[3,2-b]indole-2,4,6-triyl)tris(N,N-bis(4-methoxyphenyl)aniline) (BPT-3TPA):

[0086] (1) Under nitrogen protection, 1,4-dibromo-2-nitrobenzene and 2-tributylstannylthiophene undergo Still coupling reaction at 110°C under the catalysis of Pd(PPh3)4 to generate 2-(4-bromo-2-nitrophenyl)thiophene.

[0087]

[0088] (2) Using chlorobenzene as solvent, 2-(4-bromo-2-nitrophenyl)thiophene reacts with PPh3 at 140°C to generate 6-bromo-4H-thieno[3,2-b]indole (BPT-BR).

[0089]

[0090] (3) Synthesis of the compound 4-(6-bromo-4H-thieno[3,2-b]indol-4-yl)-N,N-bis(4-methoxyphenyl)aniline (BPT-TPA-BR):

[0091]

[0092] BPT-BR (0.36 g, 1.43 mmol), 4-iodo-N, N-bis(4-methoxyphenyl)aniline (3.69 g, 8.57 mmol), CuI (0.7 g, 0.1 mmol), 1,10-phenanthroline (0.18 g, 0.1 mmol) and ethylene glycol dimethyl ether solvent (35 mL) were added to a round-bottom flask, and potassium hydroxide aqueous solution (0.8 g, 14 mmol) was added. The reaction was refluxed under nitrogen for 24 hours. The resulting mixture was quenched with distilled water (3 mL) and then extracted with dichloromethane (300 mL). The crude product was dried over anhydrous magnesium sulfate. It was distilled under reduced pressure and purified by silica gel column chromatography to obtain BPT-TPA-BR with a yield of 82%.

[0093] (4) Synthesis of 4-(2,6-dibromo-4H-thieno[3,2-b]indol-4-yl)-N,N-bis(4-methoxyphenyl)aniline (BPT-TPA-2BR):

[0094]

[0095] At 0°C, NBS (0.18 g, 1.01 mmol) was slowly added in batches to a solution of BPT-TPA-BR (0.56 g, 1.01 mmol) in tetrahydrofuran as solvent, and the mixture was stirred at room temperature overnight. The reaction mixture was quenched with water (30 mL) and then extracted with ethyl acetate (300 mL). The crude product was dried over anhydrous magnesium sulfate. It was distilled under reduced pressure and purified by silica gel column chromatography to obtain BPT-TPA-2BRr with a yield of 89%.

[0096] (5) Synthesis of 4,4',4'-(4H-thieno[3,2-b]indole-2,4,6-triyl)tris(N,N-bis(4-methoxyphenyl)aniline) (BPT-3TPA):

[0097]

[0098] BPT-TPA-2BR (0.53 g, 0.8 mmol), OMETPA-BPIN (1.8 g, 4.18 mmol), Pd(PPh3)4 (0.02 g, 0.016 mmol) and tetrahydrofuran solvent (35 mL) were added to a round-bottom flask, and then an aqueous sodium carbonate solution (1.77 g, 2 M) was added. The reaction was refluxed under nitrogen for 12 hours. The resulting mixture was quenched with distilled water (3 mL) and then extracted with ethyl acetate (300 mL). The crude product was dried over anhydrous magnesium sulfate. It was distilled under reduced pressure and purified by silica gel column chromatography to obtain BPT-3TPA with a yield of 80%. 1 H NMR(500MHz,Methylene Chloride-d2)δ7.49–6.87(m,36H),3.83(s,18H).

[0099] Table 1

[0100]

[0101] Depend on Figure 1 The cyclic voltammetry curves show that the HOMO values ​​of the four groups of materials are -5.00, -4.99, -5.03 and -5.11 eV, respectively. Figure 2 The UV-visible absorption spectrum curves after coating show that the band gaps of the four groups of materials are 2.44eV, 2.61eV, 2.57eV and 2.62eV respectively, and the peak positions (λ onset ) are 507nm, 475nm, 483nm and 474nm respectively. The maximum absorption peak after coating (λ max film) are 428nm, 413nm, 409nm and 407nm respectively, Figure 3 The thermogravimetric analysis curves can be used to obtain the decomposition temperatures (T d ) are 417, 400, 374 and 432 °C respectively. Figure 4 The differential scanning calorimetry curves of the four groups of materials can be used to obtain the glass transition temperatures (T g ) are 55°C, 88°C, 100°C and 78°C respectively. The test data obtained from the cyclic voltammetry curves of the four groups of materials, the UV-visible absorption spectrum curves after coating, the thermogravimetric analysis curves and the differential scanning calorimetry curves are shown in Table 1.

Claims

1. A hole transport material based on thieno[3,2-b]indole, characterized in that The structural formula is:

2. The method for synthesizing a hole transport material based on thieno[3,2-b]indole according to claim 1, characterized in that: The steps include: (1) Under nitrogen protection, 1,4-dibromo-2-nitrobenzene and 2-tributylstannylthiophene undergo Still coupling reaction at 100-110°C under the catalysis of tetrakistriphenylphosphine palladium to generate 2-(4-bromo-2-nitrophenyl)thiophene. (2) Using chlorobenzene as solvent, 2-(4-bromo-2-nitrophenyl)thiophene reacts with triphenylphosphine at 135-145°C to generate 6-bromo-4H-thieno[3,2-b]indole. (3) Using DMF as solvent, 6-bromo-4H-thieno[3,2-b]indole and isooctane bromide react at 35-45°C under the action of sodium hydride to generate 6-bromo-4-(2-ethylhexyl)-4H-thieno[3,2-b]indole. Or, using DMF as solvent, 6-bromo-4H-thieno[3,2-b]indole and dodecyl bromide react at 35-45°C under the action of sodium hydride to generate 6-bromo-4-dodecyl-4H-thieno[3,2-b]indole. Or in DME and potassium hydroxide aqueous solution, 6-bromo-4H-thieno[3,2-b]indole reacts with p-iodoanisole, cuprous iodide and 1,10-phenanthroline at 90-95°C to generate 6-bromo-4-(4-methoxyphenyl)-4H-thieno[3,2-b]indole. Or in DME and potassium hydroxide aqueous solution, 6-bromo-4H-thieno[3,2-b]indole, 4-iodo-N,N-bis(4-methoxyphenyl)aniline, cuprous iodide and 1,10-phenanthroline react at 90-95°C to generate 4-(6-bromo-4H-thieno[3,2-b]indol-4-yl)-N,N-bis(4-methoxyphenyl)aniline. (4) using tetrahydrofuran as solvent, the product in step (3) and N-bromosuccinimide react at 0° C. to generate an intermediate, (5) In the presence of tetrahydrofuran and sodium carbonate aqueous solution, the intermediate and 4-boric acid ester-4',4'-dimethoxytriphenylamine are reacted at 75-80° C. under the catalysis of tetrakistriphenylphosphine palladium to generate the target product.

3. The synthesis method according to claim 2, characterized in that In step (1), the molar ratio of 4-dibromo-2-nitrobenzene to 2-tributylstannylthiophene is 1:0.

9.

4. The synthesis method according to claim 2, characterized in that In step (2), the molar ratio of 2-(4-bromo-2-nitrophenyl)thiophene to triphenylphosphine is 1:

5.

5. The synthesis method according to claim 2, characterized in that In step (3), the volume ratio of ethylene glycol dimethyl ether to water is 1:

2.

6. The synthesis method according to claim 2, characterized in that In step (5), the volume ratio of tetrahydrofuran to water is 1:

1.

7. Use of the thieno[3,2-b]indole-based hole transport material according to claim 1 in perovskite solar cells.

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