A self-assembled monolayer hole transport material based on fused thiophenoindole and preparation method and application thereof

Abstract

The application belongs to the technical field of perovskite solar cells, and specifically discloses a self-assembled monolayer hole transport material based on fused thiophene and indole as well as a preparation method and application thereof. The material has fused thiophene and indole as terminal groups, butyl as a connecting unit, and phosphoric acid as an anchoring group. The modification of the terminal groups with multiple sulfur atoms and functional units such as fluorine and chlorine can effectively regulate the solubility and wettability of the material molecules, adjust the surface work function and the surface dipole at the interface, optimize the interface passivation performance and the crystalline morphology of the perovskite layer, and promote the extraction of carriers and inhibit the interface recombination. The self-assembled monolayer hole transport material based on fused thiophene and indole according to the application can be applied to perovskite solar cells, and a photoelectric conversion efficiency of 23.66% can be obtained. Meanwhile, the battery device exhibits excellent running stability and has good commercial application potential.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, and relates to the preparation of hole transport materials, particularly to a self-assembled monolayer hole transport material based on fused thiopheneindole, its preparation method, and its application. Background Technology

[0002] Perovskite solar cells (PSCs) have emerged as a rising star in next-generation photovoltaic technology due to their superior photovoltaic performance and low production cost. After a decade of rapid development, PSCs have achieved power conversion efficiencies exceeding 26%, approaching those of traditional crystalline silicon photovoltaics. Perovskite solar cells have two main structural types: forward-biased nip structures and reverse-biased pin structures. Compared to nip structures, pin structures are more suitable for fabricating large-area, tandem solar cells because they can utilize low-temperature processes and a wider variety of carrier extraction layers, offering greater commercial potential. However, pin structures also face a challenge: improving the interface quality and stability between the hole-selective layer and the perovskite. The prevalent crystal defects that mediate charge recombination remain a major limiting factor for further performance improvements. These defects are unavoidable, especially as perovskite fabrication scales up. Furthermore, these defects are widely reported to trigger localized charge accumulation and accelerate ion migration, leading to exacerbated hysteresis behavior. Therefore, developing high-performance, novel hole transport materials for reverse-biased devices is crucial for device performance.

[0003] Self-assembled monolayers (SAMs) have achieved breakthroughs in the efficiency and stability of perovskite devices with inverted single-junction and tandem configurations due to their unique and versatile ability to control chemical and physical interface properties. SAMs materials are characterized by simple structure and flexible design, enabling effective tuning of interface energy levels and reduction of defect states through molecular engineering. They also exhibit unique advantages such as low parasitic absorption, low material consumption, compatibility with tandem perovskite solar cells, and simplified fabrication of large-area devices, making them a popular choice for fabricating high-efficiency perovskite solar cells. Therefore, developing novel SAM materials with simple structure, low cost, and excellent performance is a key issue that urgently needs to be addressed to promote the industrialization of perovskite solar cells (PSCs). Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a self-assembled monolayer hole transport material based on fused thiophene and indole. When applied to perovskite solar cells, this material can improve the photoelectric conversion efficiency of the cells and enhance device stability.

[0005] This invention is achieved through the following technical solution: A self-assembled monolayer hole transport material based on fused thiopheneindole has the following chemical structure:

[0006] Among them, R a Selected from H, F, Cl; R b Selected from H, F, Cl, and OCH3.

[0007] A further improvement to the present invention is as follows: A method for preparing a self-assembled monolayer hole transport material based on fused thiopheneindole includes the following steps: S1: Compound 1 undergoes a coupling reaction with n-butyllithium and tributyltin chloride to form intermediate 2;

[0008] S2: Intermediate 2 undergoes a coupling reaction with 2-bromonitrobenzene derivative R to generate intermediate 3;

[0009] S3: Intermediate 3 undergoes a cyclization reaction with triphenylphosphine and o-dichlorobenzene to generate intermediate 4;

[0010] S4: Intermediate 4 undergoes a substitution reaction with 1,4-dibromobutane to generate intermediate 5;

[0011] S5: Intermediate 5 undergoes a substitution reaction with triethyl phosphite to generate intermediate 6;

[0012] S6: Causes intermediate 6 to undergo a hydrolysis reaction to generate the target product, namely a self-assembled monolayer material;

[0013] Among them, R a Selected from H, F, Cl; R b Selected from H, F, Cl, and OCH3.

[0014] Further, the specific process of S1 is as follows: Compound 1 is dissolved in anhydrous THF and cooled to -78°C under argon protection. Then n-BuLi is added dropwise, and the mixture is stirred at -78°C for 1 h. Then tributyltin chloride is slowly added, and the mixture is stirred overnight at room temperature to obtain intermediate 2. The molar ratio of compound 1, n-BuLi, and tributyltin chloride is 1:1~2:1~2.

[0015] Furthermore, the specific process of S2 is as follows: intermediate 2 is reacted with compound R, Pd(PPh3)4 and toluene under argon protection, and the reaction mixture is heated to 80-120℃ for 6-18 h to prepare intermediate 3; the molar ratio of intermediate 2, compound R and tetratriphenylphosphine palladium is 1:1~1.5:0.04~0.1.

[0016] Furthermore, the specific process of S3 is as follows: intermediate 3 is mixed with triphenylphosphine in o-dichlorobenzene, and the reaction is carried out under an argon atmosphere. The reaction is carried out at 180 °C for 6-18 h to prepare intermediate 4; the molar ratio of intermediate 3 to triphenylphosphine is 1:3.

[0017] Furthermore, the specific process of S4 is as follows: intermediate 4 is dissolved in DMSO, then 1,4-dibromobutane and potassium hydroxide aqueous solution or potassium carbonate aqueous solution are added, the reaction is allowed to proceed for 10 min, tetrabutylammonium bromide (TBAB) is added to the solution, the mixture is heated to 40-100℃, and the reaction is carried out for 4-10 h to obtain intermediate 5; the molar ratio of intermediate 4, 1,4-dibromobutane and TBAB is 1:5~20:0.02~0.1.

[0018] Furthermore, the specific process of S5 is as follows: intermediate 5 is heated with triethyl phosphite in an argon atmosphere to 100-200 °C and reacted for 10-20 h to prepare intermediate 6; the molar ratio of intermediate 5 to triethyl phosphite is 1:5~40.

[0019] Furthermore, the specific process of S6 is as follows: intermediate 6 is mixed with bromotrimethylsilane in 1,4-dioxane, and a hydrolysis reaction is carried out under an argon atmosphere. The reaction is carried out at 25-100 °C for 10-24 h to prepare the target product 7, which is a self-assembled monolayer hole transport material based on fused thiopheneindole; the molar ratio of intermediate 6 to bromotrimethylsilane is 1:5~10.

[0020] Furthermore, steps S1 to S6 also include separation and purification.

[0021] A further improvement of the present invention is as follows: The above-mentioned self-assembled monolayer hole transport material based on fused thiophene and indole is applied in perovskite solar cells.

[0022] The beneficial effects of this invention are as follows: 1. This invention provides a self-assembled monolayer hole transport material based on fused thiophene-indole. The polysulfide atom characteristics of fused thiophene-indole and the modification with functional units such as F, Cl, and OCH3 enhance interface passivation, promote increased crystallinity of the perovskite layer, effectively suppress electronic defects, and significantly improve photonic quantum yield. This work contributes to a more systematic understanding of peritectic buried interfaces and provides a synergistic method for achieving precise morphology control, effective defect suppression, and energy level registration to fabricate high-efficiency perovskite solar cells.

[0023] 2. The application of the self-assembled monolayer hole transport material provided by this invention in perovskite solar cells shows that the short-circuit photocurrent density of the solar cell device reaches 25.01 mA cm⁻¹. -2 With an open-circuit voltage of 1.162 V, a fill factor of 0.8162, and a photoelectric conversion efficiency of 23.66%, it has practical significance for improving the efficiency of perovskite solar cells. Attached Figure Description

[0024] Figure 1 The nuclear magnetic resonance spectrum of formula K1 prepared in Example 1 of this invention; Figure 2 The nuclear magnetic resonance spectrum of formula KF prepared in Example 2 of this invention; Figure 3 The solid and liquid ultraviolet absorption spectra of formulas K1 and KF prepared in Examples 1 and 2 of this invention; Figure 4 Water contact angle tests of formulas K1 and KF prepared in Examples 1 and 2 of this invention; Figure 5 Wetting tests of perovskite precursor solutions of formulas K1 and KF prepared in Examples 1 and 2 of this invention; Figure 6 JV curve of perovskite solar cell prepared using formula K1 as a self-assembled monolayer hole transport material in Example 1 of the present invention. Figure 7 The JV curve of a perovskite solar cell prepared using KF as a self-assembled monolayer hole transport material, as shown in Example 2 of this invention. Detailed Implementation

[0025] The present invention will now be described in detail with reference to specific embodiments.

[0026] Example 1: Synthesis of self-assembled monolayer hole transport material K1

[0027] The specific synthetic route is as follows:

[0028] (1) Synthesis of compound 3: In a double-necked round-bottom flask, starting material 1 (1.5 g, 10.69 mmol) was dissolved in anhydrous THF (20 mL) and cooled to -78 °C under argon protection. Then, n-BuLi (6.41 mL, 16.03 mmol) was added dropwise, and the mixture was stirred at -78 °C for 1 h. Tributyltin chloride (5.16 g, 16.03 mmol) was then slowly added, and the mixture was stirred overnight at room temperature until the reaction was complete. The solvent was removed under reduced pressure, and the remaining solution in the flask was used directly for the next reaction step.

[0029] Add compound 2 (3.5 g, 5.82 mmol), compound R1 (1.76 g, 8.73 mmol), Pd(PPh3)4 (0.33 g, 0.29 mmol), and toluene (25 mL) to a 100 mL double-necked round-bottom flask obtained in the previous step. Under argon protection, the reaction mixture was heated to 100 °C and reacted for 9 h. After cooling to room temperature, dichloromethane and water were added for extraction, and the mixture was dried over anhydrous sodium sulfate. After solvent removal under reduced pressure, the mixture was purified by DCM / PE (1:4 v / v) silica gel column chromatography to give 2.57 g of the compound shown in Formula 3 as a yellow solid, in a yield of 82%.

[0030] The structural characterization data of compound formula 3 are as follows: 1 H NMR (400 MHz, DMSO) δ 7.99 (dd, J = 8.0,1.0 Hz, 1H), 7.79 – 7.73 (m, 3H), 7.70 – 7.63 (m, 1H), 7.55 (s, 1H), 7.50 (d, J = 5.2 Hz, 1H). 13 C NMR (101 MHz, DMSO) δ 149.42 (s), 140.19 (s), 139.65 (s), 138.39 (s), 133.22 (s), 132.54 (s), 130.20 (s), 129.70 (s), 127.71 (s),124.52 (s), 120.48 (d, J = 4.1 Hz). (2) Synthesis of compound 4: Compound 3 (1.27 g, 4.86 mmol), triphenylphosphine (3.82 g, 14.58 mmol), and o-dichlorobenzene (15 ml) were added sequentially to a 100 ml double-necked round-bottom flask. The reaction mixture was heated to 180 °C and refluxed for 9 h under argon protection. After cooling to room temperature, dichloromethane and water were added for extraction. The organic phase was distilled under reduced pressure, and the crude product was subjected to column chromatography (eluent: petroleum ether / dichloromethane = 50 / 1~5 / 1) to give 0.64 g of the compound shown in Formula 4 as a yellow solid, in a yield of 57%.

[0031] The structural characterization data of compound 4 are as follows: 1 H NMR (400 MHz, DMSO) δ 11.87 (s, 1H),7.73 (d, J = 7.8 Hz, 1H), 7.68 (d, J = 5.2 Hz, 1H), 7.54 (t, J = 6.5 Hz, 2H), 7.26 – 7.20 (m, 1H), 7.15 – 7.10 (m, 1H). 13 C NMR (101 MHz, DMSO) δ 141.43(s), 140.51 (s), 135.11 (s), 127.25 (s), 123.80 (s), 122.79 (d, J = 1.3 Hz),122.19 (s), 119.90 (s), 118.57 (s), 117.80 (s), 113.00 (s). (3) Synthesis of compound 5: Compound 4 (0.5 g, 2.18 mmol) was dissolved in 1,4-dibromobutane (2.35 g, 10.90 mmol), 50% KOH aqueous solution (0.61 g, 10.90 mmol), and DMSO (8 ml) in a 100 ml double-necked round-bottom flask. The reaction was stirred at room temperature for 8 h. After the reaction was complete, the mixture was extracted with saturated brine and ethyl acetate. The organic layer was dried over anhydrous Na₂SO₄ and the solvent was removed by distillation under reduced pressure. The crude product was purified by column chromatography (petroleum ether:dichloromethane 10:1 v:v) to give 0.7 g of the compound shown in Formula 5, as a yellow oil, in 88% yield.

[0032] The structural characterization data of compound Formula 5 are as follows: 1 H NMR (400 MHz, CDCl3) δ 7.74 (d, J= 7.8Hz, 1H), 7.42 (d, J = 8.3 Hz, 1H), 7.38 (q, J = 5.2 Hz, 2H), 7.34 – 7.29 (m,1H), 7.24 – 7.19 (m, 1H), 4.42 (t, J = 6.8 Hz, 2H), 3.37 (t, J = 6.5 Hz, 2H), 2.11 (dt, J = 11.5, 7.0 Hz, 2H), 1.93 (dt, J = 17.2, 6.6 Hz, 2H). 13 C NMR (101MHz, CDCl3) δ 141.62 (s), 140.16 (s), 136.32 (s), 125.25 (s), 122.85 (d, J =7.6 Hz), 121.42 (s), 119.75 (s), 118.89 (s), 117.88 (s), 44.74 (s), 33.20 (s), 30.08 (s), 29.24 (s). (4) Synthesis of compound 6: Under argon protection, compound 5 (1 g, 2.74 mmol) and triethyl phosphite (16.65 g, 54.8 mmol) were added sequentially to a 100 mL double-necked flask. The reaction mixture was heated at 170 °C for 9 h. After the reaction was complete, the solvent was distilled off under reduced pressure. The crude product was purified by column chromatography (dichloromethane:ethyl acetate 1:1 v:v) to give 1 g of the compound shown in Formula 6, a yellow oil, in 87% yield.

[0033] The structural characterization data of compound Formula 6 are as follows: 1 H NMR (400 MHz, DMSO) δ 7.99 (dd, J = 8.0,1.0 Hz, 1H), 7.79 – 7.73 (m, 3H), 7.70 – 7.63 (m, 1H), 7.55 (s, 1H), 7.50 (d, J = 5.2 Hz, 1H). 13C NMR (101 MHz, CDCl3) δ 141.53 (s), 140.18 (s), 136.33 (s), 125.15 (s), 122.82 (d, J = 1.1 Hz), 122.40 (s), 121.36 (s), 119.64 (s), 118.81 (s), 117.80 (s), 110.04 (s), 61.55 (d, J = 6.5 Hz), 45.10 (s), 31.30 (d, J = 15.3 Hz), 26.11 (s), 24.71 (s), 20.26 (d, J = 5.0 Hz), 16.41 (d, J =6.0 Hz), 1.06 (s). (5) Synthesis of equation K1: Compound 6 (1.32 g, 3.13 mmol) was dissolved in anhydrous 1,4-dioxane (8 mL) under an argon atmosphere, and trimethylbromosilane (4.07 mL, 4.07 mmol) was added dropwise. The reaction was stirred at room temperature under an argon atmosphere for 24 hours. The solvent was then partially distilled off under reduced pressure, and the liquid residue was dissolved in methanol (10 mL). Distilled water (30 mL) was then added dropwise until the solution became opaque. The product was filtered off and washed with water to give 0.72 g of the compound of formula K1 as a white solid in 88% yield.

[0034] The structural characterization data of compound K1 are as follows: 1 H NMR (400 MHz, DMSO) δ 7.79 – 7.74 (m,2H), 7.69 (d, J = 8.3 Hz, 1H), 7.60 (d, J = 5.1 Hz, 1H), 7.30 (d, J = 7.4 Hz, 1H), 7.16 (t, J = 7.5 Hz, 1H), 4.46 (t, J = 6.9 Hz, 2H), 1.98 – 1.88 (m, 2H), 1.61 – 1.47 (m, 4H). 13C NMR (101 MHz, DMSO) δ 141.58 (s), 140.42 (s), 136.34 (s), 127.45 (s), 122.86 (d, J = 2.8 Hz), 122.40 (s), 122.22 (s), 119.99 (s), 118.88 (s), 116.81 (s), 111.37 (s), 45.21 (s), 31.76 (d, J = 15.5 Hz), 28.48(s), 27.12 (s), 20.85 (d, J = 4.4 Hz). Example 2: Synthesis of KF, a self-assembled monolayer hole transport material

[0035] The specific synthetic route is as follows:

[0036] (1) Synthesis of compound 3: In a double-necked round-bottom flask, starting material 1 (1.02 g, 7.27 mmol) was dissolved in anhydrous THF (14 mL) and cooled to -78 °C under argon protection. Then, n-BuLi (4.36 mL, 10.91 mmol) was added dropwise, and the mixture was stirred at -78 °C for 1 h. Tributyltin chloride (3.5 g, 10.91 mmol) was then slowly added, and the mixture was stirred overnight at room temperature until the reaction was complete. The solvent was removed under reduced pressure, and the remaining solution in the flask was used directly for the next reaction step.

[0037] Compound 2 (2.5 g, 5.82 mmol), compound R1 (2.11 g, 9.61 mmol), Pd(PPh3)4 (0.45 g, 0.38 mmol), and toluene (20 mL) obtained in the previous step were added to a 100 mL double-necked round-bottom flask. The reaction mixture was heated to 100 °C for 9 h under argon protection. After cooling to room temperature, dichloromethane and water were added for extraction, and the mixture was dried over anhydrous sodium sulfate. After solvent removal under reduced pressure, the mixture was purified by DCM / PE (1:2 v / v) silica gel column chromatography to give 1.58 g of the compound shown in Formula 3 as a yellow solid, in 88% yield.

[0038] The structural characterization data of compound formula 3 are as follows: 1 H NMR (400 MHz, DMSO) δ 8.12 (dd, J= 9.0, 5.1 Hz, 1H), 7.78 (d, J = 5.3 Hz, 1H), 7.65 (dd, J = 9.2, 2.8 Hz, 1H), 7.62(s, 1H), 7.57 – 7.53 (m, 1H), 7.51 (dd, J = 6.8, 1.6 Hz, 1H). 13 C NMR (101MHz, DMSO) δ 164.71 (s), 162.20 (s), 145.80 (d, J = 2.9 Hz), 140.60 (s), 139.54 (s), 137.21 (d, J = 1.5 Hz), 130.90 (d, J = 10.0 Hz), 130.13 (s), 127.71 (d, J = 10.3 Hz), 121.19 (s), 120.48 (s), 119.35 (d, J = 24.6 Hz), 117.03 (d, J = 23.5 Hz). (2) Synthesis of compound 4: Compound 3 (1.24 g, 4.44 mmol), triphenylphosphine (3.49 g, 13.31 mmol), and o-dichlorobenzene (20 ml) were added sequentially to a 100 ml double-necked round-bottom flask. The reaction mixture was heated to 180 °C and refluxed for 9 h under argon protection. After cooling to room temperature, dichloromethane and water were added for extraction. The organic phase was distilled under reduced pressure, and the crude product was subjected to column chromatography (eluent: petroleum ether / dichloromethane = 50 / 1~5 / 1) to give 0.72 g of the compound shown in Formula 4 as a yellow solid, in a yield of 65%.

[0039] The structural characterization data of compound 4 are as follows: 1 H NMR (400 MHz, DMSO) δ 11.95 (s, 1H),7.71 (d, J = 5.2 Hz, 1H), 7.60 (dd, J = 9.8, 2.6 Hz, 1H), 7.55 (d, J = 5.2Hz, 1H), 7.52 (dd, J = 8.9, 4.6 Hz, 1H), 7.07 (td,J = 9.2, 2.6 Hz, 1H). 13 CNMR (101 MHz, DMSO) δ 158.45 (s), 156.13 (s), 142.18 (s), 137.07 (s), 136.78 (s), 127.89 (s), 123.58 (s), 122.94 (d, J = 11.1 Hz), 122.23 (s), 117.59 (d, J = 4.5 Hz), 113.82 (d, J = 9.8 Hz), 110.52 (d, J = 25.8 Hz), 103.93 (d, J =24.9 Hz). (3) Synthesis of compound 5: Compound 4 (1 g, 4.04 mmol) was dissolved in 1,4-dibromobutane (4.36 g, 20.2 mmol), 50% KOH aqueous solution (1.13 g, 20.2 mmol), and DMSO (8 ml) in a 100 ml double-necked round-bottom flask. The reaction was stirred at room temperature for 8 h. After the reaction was complete, the mixture was extracted with saturated brine and ethyl acetate. The organic layer was dried over anhydrous Na₂SO₄ and the solvent was removed by distillation under reduced pressure. The crude product was purified by column chromatography (petroleum ether:dichloromethane 10:1 v:v) to give 0.7 g of the compound shown in Formula 5, as a yellow oil, in 88% yield.

[0040] The structural characterization data of compound Formula 5 are as follows: 1 H NMR (400 MHz, CDCl3) δ 7.42 – 7.34 (m,3H), 7.29 (dd, J = 8.9, 4.2 Hz, 1H), 7.03 (td, J = 9.1, 2.5 Hz, 1H), 4.36 (t, J = 6.8 Hz, 2H), 3.36 (t, J = 6.4 Hz, 2H), 2.12 – 2.03 (m, 2H), 1.90 (dt, J =17.1, 6.6 Hz, 2H). 13C NMR (101 MHz, CDCl3) δ 158.82 (s), 156.48 (s), 142.10 (s), 137.63 (s), 136.63 (s), 125.81 (s), 122.94 (d, J = 10.6 Hz), 122.60 (s), 121.42 (s), 117.31 (d, J = 4.5 Hz), 110.48 (dd, J = 17.9, 11.8 Hz), 104.23 (d, J = 24.8 Hz), 44.97 (s), 33.02 (s), 30.00 (s), 29.17 (s). (4) Synthesis of compound 6: Under argon protection, compound 5 (2.4 g, 6.28 mmol) and triethyl phosphite (17.15 g, 94.2 mmol) were added sequentially to a 100 mL double-necked flask. The reaction mixture was heated at 170 °C for 9 h. After the reaction was complete, the solvent was distilled off under reduced pressure. The crude product was purified by column chromatography (dichloromethane:ethyl acetate 1:1 v:v) to give 2.3 g of the compound shown in Formula 6, a yellow oil, in 89% yield.

[0041] The structural characterization data of compound Formula 6 are as follows: 1 H NMR (400 MHz, DMSO) δ 7.78 (d, J = 5.2Hz, 1H), 7.70 (dd, J = 9.0, 4.4 Hz, 1H), 7.63 (dd, J = 9.7, 2.5 Hz, 1H), 7.59(d, J = 5.2 Hz, 1H), 7.12 (td, J = 9.3, 2.6 Hz, 1H), 4.46 (t, J = 6.8 Hz,2H), 3.89 – 3.80 (m, 4H), 1.96 – 1.86 (m, 2H), 1.75 – 1.66 (m, 2H), 1.48(ddd, J = 20.2, 11.7, 6.6 Hz, 2H), 1.09 (t, J = 7.1 Hz, 6H). 13C NMR (101 MHz, CDCl3) δ 158.78 (s), 156.44 (s), 142.03 (s), 137.65 (s), 136.68 (s), 125.76 (s), 123.25 – 121.91 (m), 121.36 (s), 117.23 (d, J = 4.5 Hz), 110.72 – 110.41(m), 110.20 (s), 104.13 (d, J = 24.8 Hz), 61.56 (d, J = 6.5 Hz), 45.31 (s), 31.25 (d, J = 15.2 Hz), 26.08 (s), 24.67 (s), 20.23 (d, J = 5.0 Hz), 16.44(dd, J = 10.0, 6.1 Hz). (5) Synthesis of formula KF: Compound 6 (1.51 g, 3.43 mmol) was dissolved in anhydrous 1,4-dioxane (10 mL) under an argon atmosphere, and trimethylbromosilane (5.15 mL, 5.15 mmol) was added dropwise. The reaction was stirred at room temperature under an argon atmosphere for 24 hours. The solvent was then partially distilled off under reduced pressure, and the liquid residue was dissolved in methanol (10 mL). Distilled water (30 mL) was then added dropwise until the solution became opaque. The product was filtered off and washed with water to give 0.83 g of the compound of formula KF as a yellow solid, in a yield of 62.8%.

[0042] The structural characterization data of the KF compound are as follows: 1 H NMR (400 MHz, DMSO) δ 7.79 (d, J = 5.2Hz, 1H), 7.71 (dd, J = 9.0, 4.4 Hz, 1H), 7.65 (dd, J = 9.7, 2.5 Hz, 1H), 7.61(d, J = 5.2 Hz, 1H), 7.13 (td, J = 9.2, 2.6 Hz, 1H), 4.46 (t, J = 6.9 Hz,2H), 1.96 – 1.87 (m, 2H), 1.54 (dd, J= 17.7, 8.5 Hz, 4H). 13 C NMR (101 MHz, DMSO) δ 158.56 (s), 156.24 (s), 142.35 (s), 137.80 (s), 137.07 (s), 128.10 (s), 122.66 (s), 122.27 (s), 116.44 (d, J = 4.5 Hz), 112.41 (d, J = 9.7 Hz), 110.57 (d, J = 25.9 Hz), 104.28 (d, J = 25.0 Hz), 45.40 (s), 31.72 (d, J =15.6 Hz), 28.44 (s), 27.08 (s), 20.81 (d, J = 4.4 Hz). Example 3

[0043] The nuclear magnetic resonance spectrum of the self-assembled monolayer hole transport material K1 prepared in Example 1 is shown below. Figure 1 As shown. Simultaneously, the solid-state UV-Vis absorption spectrum of this molecule exhibits a significant red shift compared to its liquid state, demonstrating strong intermolecular interactions (…). Figure 3 As shown). Simultaneously, the water contact angle ( Figure 4 ) and perovskite precursor wettability ( Figure 5 Tests show that the material has good hydrophobicity and wetting properties.

[0044] This embodiment provides a perovskite solar cell prepared according to formula K1 in Example 1, based on the literature: M. Liu; L. Bi; W. Jiang; et al. Adv. Mater. 2023, 2304415. The test light source was AM 1.5 (solarsimulator-Oriel 91160-1000, 300W), and data acquisition was performed using a Keithley 2400 digital source meter. Test results are shown below. Figure 6 The short-circuit photocurrent density of the battery device reached 24.91 mA cm⁻¹. -2 The open-circuit voltage is 1.151 V, the fill factor (FF) is 0.8128, and the photoelectric conversion efficiency reaches 23.31%. Example 4

[0045] The nuclear magnetic resonance spectrum of the self-assembled monolayer hole transport material KF prepared in Example 2 is shown below. Figure 2As shown. Simultaneously, the solid-state UV-Vis absorption spectrum of this molecule exhibits a significant red shift compared to its liquid state, which is beneficial for forming densely and orderly arranged SAMs thin films. Figure 3 As shown). Simultaneously, the water contact angle ( Figure 4 ) and perovskite precursor wettability ( Figure 5 Tests show that this material has better wettability and water resistance compared to K1.

[0046] This embodiment provides a KF model prepared in Example 1, which is used to fabricate a perovskite solar cell according to the literature: M. Liu; L. Bi; W. Jiang; et al. Adv. Mater. 2023, 2304415. The test light source was AM 1.5 (solarsimulator-Oriel 91160-1000, 300W), and data acquisition was performed using a Keithley 2400 digital source meter. The test results are shown below. Figure 7 The short-circuit photocurrent density of the battery device reached 25.01 mA cm⁻¹. -2 The open-circuit voltage is 1.162 V, the fill factor (FF) is 0.8162, and the photoelectric conversion efficiency reaches 23.66%.

[0047] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. The application of a self-assembled monolayer hole transport material based on fused thiopheneindole in perovskite solar cells, characterized in that, The chemical structural formula of the hole transport material is shown below: 。 2. The application according to claim 1, characterized in that, The self-assembled monolayer hole transport material based on fused thiopheneindole is prepared by the following steps: S1: Compound 1 undergoes a coupling reaction with n-butyllithium and tributyltin chloride to form intermediate 2; S2: Intermediate 2 undergoes a coupling reaction with 2-bromonitrobenzene derivative R to generate intermediate 3; S3: Intermediate 3 undergoes a cyclization reaction with triphenylphosphine and o-dichlorobenzene to generate intermediate 4; S4: Intermediate 4 undergoes a substitution reaction with 1,4-dibromobutane to generate intermediate 5; S5: Intermediate 5 undergoes a substitution reaction with triethyl phosphite to generate intermediate 6; S6: Causes intermediate 6 to undergo a hydrolysis reaction to generate the target product, namely the self-assembled monolayer material KF; 。 3. The application according to claim 2, characterized in that: The specific process of S1 is as follows: Compound 1 is dissolved in anhydrous THF, cooled to -78°C under argon protection, then n-BuLi is added dropwise, stirred at -78°C for 1 h, then tributyltin chloride is slowly added, and stirred at room temperature overnight to obtain intermediate 2; the molar ratio of compound 1, n-BuLi and tributyltin chloride is 1:1~2:1~2.

4. The application according to claim 2, characterized in that: The specific process of S2 is as follows: intermediate 2 is reacted with compound R, Pd(PPh3)4 and toluene under argon protection, and the reaction mixture is heated to 80-120℃ for 6-18 h to prepare intermediate 3; the molar ratio of intermediate 2, compound R and tetratriphenylphosphine palladium is 1:1~1.5:0.04~0.

1.

5. The application according to claim 2, characterized in that: The specific process of S3 is as follows: intermediate 3 is mixed with triphenylphosphine in o-dichlorobenzene and reacted under an argon atmosphere. The reaction is carried out at 180 °C for 6-18 h to prepare intermediate 4; the molar ratio of intermediate 3 to triphenylphosphine is 1:

3.

6. The application according to claim 2, characterized in that: The specific process of S4 is as follows: intermediate 4 is dissolved in DMSO, then 1,4-dibromobutane and potassium hydroxide aqueous solution or potassium carbonate aqueous solution are added, the reaction is allowed to proceed for 10 min, tetrabutylammonium bromide (TBAB) is added to the solution, the mixture is heated to 40-100℃, and the reaction is carried out for 4-10 h to obtain intermediate 5; the molar ratio of intermediate 4, 1,4-dibromobutane and TBAB is 1:5~20:0.02~0.

1.

7. The application according to claim 2, characterized in that: The specific process of S5 is as follows: intermediate 5 is reacted with triethyl phosphite under an argon atmosphere at 100-200 °C for 10-20 h to prepare intermediate 6; the molar ratio of intermediate 5 to triethyl phosphite is 1:5~40.

8. The application according to claim 2, characterized in that: The specific process of S6 is as follows: intermediate 6 is mixed with bromotrimethylsilane in 1,4-dioxane and hydrolyzed under an argon atmosphere for 10-24 h at 25-100 °C to prepare the target product 7, which is a self-assembled monolayer hole transport material based on fused thiophene and indole; the molar ratio of intermediate 6 to bromotrimethylsilane is 1:5~10.

9. The application according to any one of claims 2 to 8, characterized in that: S1 to S6 also include separation and purification steps.

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