A self-assembled monolayer hole transport material based on alkyl polyphosphate anchoring groups, and its synthesis method and application

Abstract

The present invention discloses a self-assembled monolayer hole transport material based on an alkyl polyphosphate anchoring group, a synthesis method thereof, and an application in an inverted perovskite solar cell. The present invention uses carbazole or 3,6-diphenylcarbazole with good hole transport properties as a parent core, and achieves complete coverage and stable self-assembly of the material on the substrate surface by improving the anchoring group from traditional alkyl monophosphate to alkyl diphosphate and triphosphate. The synthesis method of the present invention is simple and the synthesis cost is low. The prepared material can achieve the dual functions of hole transport and perovskite interface passivation, while enhancing the self-assembly strength and stability. When the material is used as a hole transport layer in an inverted perovskite solar cell, a photoelectric conversion efficiency of >20% can be obtained without doping, and the material has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of hole transport materials, and in particular to a self-assembled monolayer hole transport material, a synthesis method and an application thereof. Background Art

[0002] Energy is the foundation of human survival and development. Solar energy, due to its clean and sustainable characteristics, is attracting widespread attention and research from the entire society. In recent years, organic-inorganic hybrid perovskite solar cells (PSCs) have achieved rapid development due to their unique photovoltaic properties, with their photoelectric conversion efficiency (PCE) rapidly increasing from 3.8% to 25.8%. Among various PSC structures, inverted PSCs are suitable for all-solution coating manufacturing, with advantages such as low cost, flexibility, and no hysteresis, which is expected to help PSCs achieve industrialization at an early date.

[0003] A major bottleneck in the current industrialization of inverted PSCs lies in hole transport materials (HTLs). Poly (bis(4-phenyl)(2,4,6-trimethylphenyl)amine) (PTAA) is currently the most commonly used HTL material, but PTAA itself is expensive, has low hole mobility, and is mismatched with the perovskite energy level, making it almost impossible for PTAA to be used in the industrialization of inverted PSCs. In response to the problems existing in PTAA, a variety of new hole transport materials represented by self-assembled monolayers (SAMs) have been developed. The unique advantages of SAM-HTL include: (1) the amount of SAM molecules used is extremely small, which can maximize atom economy; (2) SAM films are suitable for large-scale manufacturing on industrial production lines; (3) SAM molecules can be chemically bonded to the substrate and have good solution processability; (4) SAM films are extremely thin, which is conducive to reducing efficiency loss. Although more than 20 SAM-HTL materials have been reported in the current literature, most of them focus on how to improve photovoltaic performance by optimizing molecular design, but ignore the stability of SAM-HTL. As an important component of the stability of inverted PSCs, how to improve the stability of SAM-HTL plays an important role in the industrialization process of inverted PSCs. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a self-assembled monolayer hole transport material with good hole transport properties and stable interface.

[0005] In order to achieve the above-mentioned object, the present invention designs a self-assembled monolayer hole transport material, which has carbazole or diphenylcarbazole as a parent core and alkyl diphosphate or alkyl triphosphate as a terminal. The material has the following structural formula:

[0006]

[0007] or

[0008]

[0009] or

[0010]

[0011] or

[0012]

[0013] Another object of the present invention is to provide a method for synthesizing the above-mentioned hole transport material, which specifically comprises the following steps:

[0014] When the parent core is carbazole and the anchor group is alkyl diphosphonic acid (CZ-C4P2OH), the specific synthesis steps are as follows:

[0015] Step 1: Carbazole (CZ) reacts with 1,3-dibromopropane to obtain 9-(3-bromopropyl)-carbazole (CZ-C3Br):

[0016]

[0017] Step 2: CZ-C3Br and tetraethyl methylene diphosphate react to obtain (4-(9-carbazolyl)butyl-1,1-diyl)diphosphonic acid tetraethyl ester (CZ-C4P2OR):

[0018]

[0019] Step 3: CZ-C4P2OR is hydrolyzed to obtain (4-(9-carbazolyl)butyl-1,1-diyl)bisphosphonic acid (CZ-C4P2OH):

[0020]

[0021] Furthermore, in step 1, the strong base used in the reaction is potassium hydroxide; the phase transfer catalyst used in the reaction is tetrabutylammonium bromide; and the reaction temperature is 0-90°C.

[0022] Furthermore, in step 2, the reaction is carried out under the protection of an inert gas such as nitrogen or argon; the strong base used in the reaction is sodium hydride; the reaction solvent is tetrahydrofuran; and the reaction temperature is 0-70°C.

[0023] Furthermore, in step three, the reaction is carried out under the protection of an inert gas such as nitrogen or argon; the reaction solvent is tetrahydrofuran; the reaction temperature is 0-50° C.; the hydrolysis reagent used in the reaction is trimethylsilyl bromide; and the quenching reagent used in the reaction is methanol.

[0024] When the parent core is diphenylcarbazole and the anchor group is alkyl diphosphonic acid (BCZ-C4P2OH), the specific synthesis steps are as follows:

[0025] Step 1: 3,6-diphenylcarbazole (BCZ) and 1,3-dibromopropane react to obtain 3,6-diphenyl-9-(3-bromopropyl)-carbazole (BCZ-C3Br):

[0026]

[0027] Step 2: BCZ-C3Br and tetraethyl methylene diphosphate react to obtain (4-(3,6-diphenyl-9-carbazolyl)butyl-1,1-diyl)diphosphonic acid tetraethyl ester (BCZ-C4P2OR):

[0028]

[0029] Step 3: BCZ-C4P2OR is hydrolyzed to obtain (4-(3,6-diphenyl-9-carbazolyl)butyl-1,1-diyl)bisphosphonic acid (BCZ-C4P2OH):

[0030]

[0031] Furthermore, in step 1, the strong base used in the reaction is potassium hydroxide; the phase transfer catalyst used in the reaction is tetrabutylammonium bromide; and the reaction temperature is 0-90°C.

[0032] Furthermore, in step 2, the reaction is carried out under the protection of an inert gas such as nitrogen or argon; the strong base used in the reaction is sodium hydride; the reaction solvent is tetrahydrofuran; and the reaction temperature is 0-70°C.

[0033] Furthermore, in step three, the reaction is carried out under the protection of an inert gas such as nitrogen or argon; the reaction solvent is tetrahydrofuran; the reaction temperature is 0-50° C.; the hydrolysis reagent used in the reaction is trimethylsilyl bromide; and the quenching reagent used in the reaction is methanol.

[0034] When the parent core is carbazole and the anchor group is alkyl triphosphate (CZ-C4P3OH), the specific synthesis steps are as follows:

[0035] Step 1: CZ-C4P2OR reacts with diethylphosphite chloride to obtain hexaethyl (4-(9-carbazolyl)butyl-1,1,1-triyl)triphosphonate (CZ-C4P3OR):

[0036]

[0037] Step 2: CZ-C4P3OR is hydrolyzed to obtain (4-(9-carbazolyl)butyl-1,1,1-triyl)triphosphonic acid (CZ-C4P3OH):

[0038]

[0039] Furthermore, in step 1, the strong base used in the reaction is sodium bis(trimethylsilyl)amide; the oxidant used in the reaction is hydrogen peroxide; the reaction solvent is tetrahydrofuran; and the reaction temperature is 0-50°C.

[0040] Furthermore, in step 2, the reaction is carried out under the protection of an inert gas such as nitrogen or argon; the reaction solvent is tetrahydrofuran; the reaction temperature is 0-50° C.; the hydrolysis reagent used in the reaction is trimethylsilyl bromide; and the quenching reagent used in the reaction is methanol.

[0041] When the parent core is diphenylcarbazole and the anchor group is alkyl triphosphate (BCZ-C4P3OH), the specific synthesis steps are as follows:

[0042] Step 1: BCZ-C4P2OR reacts with diethylphosphite chloride to obtain (4-(3,6-diphenyl-9-carbazolyl)butyl-1,1,1-triyl)triphosphonic acid hexaethyl ester (BCZ-C4P3OR):

[0043]

[0044] Step 2: BCZ-C4P3OR is hydrolyzed to obtain (4-(3,6-diphenyl-9-carbazolyl)butyl-1,1,1-triyl)triphosphonic acid (BCZ-C4P3OH):

[0045]

[0046] Furthermore, in step 1, the strong base used in the reaction is sodium bis(trimethylsilyl)amide; the oxidant used in the reaction is hydrogen peroxide; the reaction solvent is tetrahydrofuran; and the reaction temperature is 0-50°C.

[0047] Furthermore, in step 2, the reaction is carried out under the protection of an inert gas such as nitrogen or argon; the reaction solvent is tetrahydrofuran; the reaction temperature is 0-50° C.; the hydrolysis reagent used in the reaction is trimethylsilyl bromide; and the quenching reagent used in the reaction is methanol.

[0048] The third object of the present invention is to apply the self-assembled monolayer hole transport material based on alkyl polyphosphate anchoring groups to inverted perovskite solar cells.

[0049] Furthermore, in the perovskite solar cell structure, the perovskite solution is spin-coated onto the surface of the self-assembled monolayer hole transport material.

[0050] Furthermore, the structure of the perovskite solar cell is glass / ITO / SAM-HTL / perovskite / C 60 / BCP / Cu, the SAM-HTL is a self-assembled monolayer hole transport material based on alkyl polyphosphate anchoring groups.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] The present invention discloses a self-assembled monolayer hole transport material based on an alkyl polyphosphate anchoring group. The currently commonly used alkyl monophosphate anchoring group is improved to an alkyl polyphosphate, which multiplies the self-assembly probability of the material and the substrate, helps to achieve complete coverage and strong bonding of the self-assembled monolayer hole transport material on the substrate surface, thereby improving interface stability and reducing photovoltaic performance loss at the interface. With carbazole and diphenylcarbazole as the parent nucleus, while ensuring the excellent hole transport performance of the material, the molecular dipole and interface properties are regulated to improve the photovoltaic performance of the material. The present invention adopts a simplified synthesis step and synthesizes the self-assembled monolayer hole transport material based on the alkyl polyphosphate anchoring group at a low cost. The laboratory calculated material cost is 20$ / g, which is much lower than the currently widely used PTAA (1980$ / g). In addition, thanks to the self-assembled monolayer characteristics, the synthesized hole transport material has maximized atom economy and can be continuously prepared into large-area thin films by an immersion method, which is suitable for industrial applications of PSCs. When the synthesized material is used as the hole transport layer of inverted perovskite solar cells, a high open circuit voltage of >1.1V and a photoelectric conversion efficiency of >20% can be obtained without doping. At the same time, the lifespan and stability of perovskite solar cells are greatly improved, which is expected to help the industrialization of perovskite solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 JV curve of CZ-C4P2OH prepared by the present invention as a hole transport material for perovskite solar cells;

[0054] Figure 2 JV curve of BCZ-C4P2OH prepared by the present invention as a hole transport material for perovskite solar cells;

[0055] Figure 3 The JV curve of CZ-C4P3OH prepared by the present invention as a hole transport material for perovskite solar cells;

[0056] Figure 4 JV curve of BCZ-C4P3OH prepared by the present invention as a hole transport material for perovskite solar cells;

[0057] Figure 5 Schematic diagram of the structure of the perovskite solar cell prepared by the present invention. DETAILED DESCRIPTION

[0058] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0059] Example 1:

[0060] Synthesis of CZ-C4P2OH:

[0061]

[0062] Step 1:

[0063] To a 250 mL two-necked flask were added CZ (5.00 g, 29.90 mmol), tetrabutylammonium bromide (1.45 g, 4.49 mmol), 1,3-dibromopropane (120.74 g, 598.05 mmol), and a 50% aqueous solution of KOH (16.78 g, 149.51 mmol). The reaction mixture was heated to 60°C and allowed to react for 24 hours. After cooling to room temperature, the reaction mixture was washed with water and extracted with dichloromethane three times. This process was repeated, dried over anhydrous magnesium sulfate, filtered, and the solvent removed on a rotary evaporator to obtain the crude product. The crude product was separated by chromatography using petroleum ether / dichloromethane (3:1, v / v) as the eluent to obtain CZ-C3Br as a colorless oil in an 80% yield.

[0064] The H-NMR spectrum of CZ-C3Br prepared by the above method is: 1 H NMR (400MHz, CDCl3, δ): 8.11 (d, J = 7.8Hz, 2H), 7.49 (d, J = 3.2Hz, 4H), 7.26 (td, J = 4 .9,2.7Hz,2H),4.50(t,J=6.6Hz,2H),3.39(t,J=6.2Hz,2H),2.44(t,J=6.3Hz,2H).

[0065] Step 2:

[0066] Under nitrogen, a 100-mL two-necked flask was charged sequentially with 30 mL of tetrahydrofuran, tetraethylmethylene diphosphate (3.81 g, 13.22 mmol), and sodium hydride (0.56 g, 13.88 mmol). CZ-C3Br (4 g, 13.88 mmol) was then slowly added dropwise. The reaction mixture was heated at reflux for 24 h. After cooling to room temperature, the reaction mixture was washed with water and extracted with ethyl acetate three times. The extraction was then dried over anhydrous magnesium sulfate and filtered. The solvent was then removed by rotary evaporation to yield the crude product. The crude product was separated by chromatography using petroleum ether / ethyl acetate (1:1, v / v) as the eluent to obtain CZ-C4P2OR as a colorless oil in an 85% yield.

[0067] The H-NMR spectrum of CZ-C4P2OR prepared by the above method is as follows: 1H NMR (400MHz, CDCl3, δ): 8.12–8.02(m,2H),7.42(p,J=7.7Hz,4H),7.24–7.17(m,2H),4.33(dt,J=9.0,4.5Hz, 2H), 4.04(ddt,J=17.6,15.3,5.6Hz,8H),2.28–2.11(m,3H),2.02–1.88(m,2H),1.19(qd,J=7.1,3.5Hz,12H).

[0068] Step 3:

[0069] Under nitrogen, CZ-C4P2OR (1 g, 2.02 mmol) and 15 mL of anhydrous tetrahydrofuran were added to a 100 mL two-necked flask. Trimethylsilyl bromide (6.18 g, 40.36 mmol) was slowly added dropwise at room temperature and stirred for 24 hours. The reaction was quenched by the addition of 20 mL of anhydrous methanol and stirred for 3 hours. Finally, 300 mL of deionized water was added and stirred for 24 hours. The reaction mixture was filtered and washed with water. The filter cake was redissolved in tetrahydrofuran, precipitated in petroleum ether, and filtered. This reaction was repeated three times to obtain CZ-C4P2OH as a white solid in a 70% yield.

[0070] The H-NMR spectrum of CZ-C4P2OH prepared by the above method is: 1 H NMR (400MHz, DMSO-d6, δ): 8.12 (d, J = 7.6 Hz, 2H), 7.58 (d, J = 8.3 Hz, 2H), 7.42 (t, J = 7.8 Hz, 2H), 7.18 (dt, J = 7.7, 3.8 Hz, 2H), 1.94 (d, J = 49.7 Hz, 7H).

[0071] Example 2:

[0072] Synthesis of BCZ-C4P2OH:

[0073]

[0074] Step 1:

[0075] To a 250 mL two-necked flask were added BCZ (5.00 g, 15.65 mmol), tetrabutylammonium bromide (0.76 g, 2.35 mmol), 1,3-dibromopropane (63.21 g, 313.08 mmol), and 50% aqueous KOH (8.78 g, 78.27 mmol). The reaction mixture was heated to 60°C and allowed to react for 24 hours. After cooling to room temperature, the reaction mixture was washed with water and extracted with dichloromethane three times. This process was repeated, dried over anhydrous magnesium sulfate, filtered, and the solvent removed on a rotary evaporator to obtain the crude product. The crude product was separated by chromatography using petroleum ether / dichloromethane (3:1, v / v) as the eluent to obtain BCZ-C3Br as a colorless oil in an 83% yield.

[0076] The H-NMR spectrum of BCZ-C3Br prepared by the above method is: 1 H NMR (400MHz, CDCl3, δ): 8.36 (s, 2H), 7.73 (t, J=8.3Hz, 6H), 7.55 (dd, J=8.6, 3.0Hz, 2H), 7.48 (t, J= 7.6Hz, 4H), 7.35 (t, J = 7.4Hz, 2H), 4.54 (t, J = 5.6Hz, 2H), 3.52–3.27 (m, 2H), 2.49 (q, J = 5.6Hz, 2H).

[0077] Step 2:

[0078] Under nitrogen, a 100-mL two-necked flask was charged sequentially with 30 mL of tetrahydrofuran, tetraethylmethylene diphosphate (1.87 g, 6.49 mmol), and sodium hydride (0.27 g, 6.81 mmol). BCZ-C3Br (3 g, 6.81 mmol) was then slowly added dropwise. The reaction mixture was heated at reflux for 24 h. After cooling to room temperature, the reaction mixture was washed with water and extracted with ethyl acetate three times. The extraction was then dried over anhydrous magnesium sulfate and filtered. The solvent was then removed by rotary evaporation to obtain the crude product. The crude product was separated by chromatography using petroleum ether / ethyl acetate (1:1, v / v) as the eluent to obtain BCZ-C4P2OR as a colorless oil in a 72% yield.

[0079] The H-NMR spectrum of BCZ-C4P2OR prepared by the above method is as follows: 1H NMR (400MHz, CDCl3, δ): 8.34 (d, J = 2.0Hz, 2H), 7.71 (dd, J = 8.3, 3.6Hz, 6H), 7.53–7.43 (m, 6H), 7.34 (d, J = 7.3Hz, 2H), 4.38 (s, 2H), 4.13–3.95 (m, 8H), 2.27 (d, J = 7.3Hz, 3H), 2.05 (d, J = 7.4Hz, 2H), 1.20 (dt, J = 9.7, 7.1Hz, 12H).

[0080] Step 3:

[0081] Under nitrogen, BCZ-C4P2OR (1 g, 1.54 mmol) and 15 mL of anhydrous tetrahydrofuran were added to a 100 mL two-necked flask. Trimethylsilyl bromide (4.73 g, 40.36 mmol) was slowly added dropwise at room temperature and stirred for 24 hours. The reaction was quenched by the addition of 20 mL of anhydrous methanol and stirred for 3 hours. Finally, 300 mL of deionized water was added and stirred for 24 hours. The reaction mixture was filtered and washed with water. The filter cake was redissolved in tetrahydrofuran, precipitated in petroleum ether, and filtered. This reaction was repeated three times to obtain BCZ-C4P2OH as a white solid in a 66% yield.

[0082] The H-NMR spectrum of CZ-C4P2OH prepared by the above method is: 1 H NMR (400MHz, DMSO-d6, δ): 8.60 (s, 2H), 7.78 (t, J = 7.6Hz, 6H), 7.68 (d, J = 8.6Hz, 2H), 7.47 (t, J = 7.6Hz ,4H),7.32(t,J=7.3Hz,2H),4.40(t,J=7.4Hz,2H),2.05(q,J=7.8,7.0Hz,3H),1.94(d,J=26.3Hz,2H).

[0083] Example 3:

[0084] Synthesis of CZ-C4P3OH:

[0085]

[0086] Step 1:

[0087] Under nitrogen and in an ice bath, a 100 mL two-necked flask was charged sequentially with CZ-C4P2OR (1.00 g, 2.02 mmol), 20 mL of anhydrous tetrahydrofuran, and sodium bis(trimethylsilyl)amide (0.55 g, 3.03 mmol). After a half-hour ice bath, diethylphosphite chloride (0.63 g, 4.04 mmol) was slowly added dropwise. The reaction mixture was warmed to room temperature and allowed to react for 3 hours. Then, 3 mL of hydrogen peroxide was slowly added and stirred overnight. The reaction mixture was washed with water and extracted with dichloromethane three times. After this extraction, the mixture was dried over anhydrous magnesium sulfate and filtered. The solvent was removed by rotary evaporation to yield the crude product. The crude product was separated by chromatography using ethyl acetate as the eluent to obtain CZ-C4P3OR as a colorless oil in a 63% yield.

[0088] The H-NMR spectrum of CZ-C4P3OR prepared by the above method is as follows: 1 H NMR (400MHz, CDCl3, δ): 8.02 (s, 2H), 7.39 (dd, J = 27.6, 12.3Hz, 4H), 7.21 (s, 2H), 4.30 (t, J = 7. 5Hz,2H),4.25–3.70(m,12H),2.57(s,2H),1.94(s,2H),1.26(ddt,J=63.1,14.5,7.2Hz,18H).

[0089] Step 2:

[0090] Under nitrogen, CZ-C4P3OR (1.00 g, 1.58 mmol) and 15 mL of anhydrous tetrahydrofuran were added to a 100 mL two-necked flask. Trimethylsilyl bromide (7.27 g, 47.50 mmol) was slowly added dropwise at room temperature and stirred for 24 hours. The reaction was quenched by the addition of 20 mL of anhydrous methanol and stirred for 3 hours. Finally, 300 mL of deionized water was added and stirred for 24 hours. The reaction mixture was filtered and washed with water. The filter cake was redissolved in tetrahydrofuran, precipitated in petroleum ether, and filtered. This reaction was repeated three times to obtain CZ-C4P3OH as a white solid in a 67% yield.

[0091] The H-NMR spectrum of CZ-C4P3OH prepared by the above method is: 1 H NMR (400MHz, DMSO-d6, δ): 8.19 (d, J = 23.3Hz, 2H), 7.48 (d, J = 47.5Hz, 4H), 7.1 6(s,2H),4.23(t,J=7.0Hz,2H),2.38(d,J=8.2Hz,2H),2.11(t,J=7.6Hz,2H).

[0092] Example 4:

[0093] Synthesis of BCZ-C4P3OH:

[0094]

[0095] Step 1:

[0096] Under nitrogen and in an ice bath, a 100 mL two-necked flask was charged sequentially with BCZ-C4P2OR (1.00 g, 1.54 mmol), 20 mL of anhydrous tetrahydrofuran, and sodium bis(trimethylsilyl)amide (0.43 g, 2.32 mmol). After a half-hour ice bath, diethylphosphite chloride (0.48 g, 3.09 mmol) was slowly added dropwise. The reaction mixture was warmed to room temperature and allowed to react for 3 hours. Then, 3 mL of hydrogen peroxide was slowly added and stirred overnight. The reaction mixture was washed with water and extracted with dichloromethane three times. After repeated extraction, the mixture was dried over anhydrous magnesium sulfate and filtered. The solvent was removed by rotary evaporation to yield the crude product. The crude product was separated by chromatography using ethyl acetate as the eluent to obtain BCZ-C4P3OR as a colorless oil in a 60% yield.

[0097] The H-NMR spectrum of BCZ-C4P3OR prepared by the above method is as follows: 1 H NMR (400MHz, CDCl3, δ): 8.32 (d, J = 16.1Hz, 2H), 7.69 (t, J = 8.7Hz, 6H), 7.47 (t, J = 7.8Hz, 6H), 7.35 (d, J = 7.4Hz, 2H), 4.49 –4.27(m,2H),4.12(ddt,J=26.5,18.7,9.7Hz,12H),2.28(d,J=28.5Hz,2H),2.03(d,J=23.3Hz,2H),1.45–1.03(m,18H).

[0098] Step 2:

[0099] Under nitrogen, BCZ-C4P3OR (1.00 g, 1.28 mmol) and 15 mL of anhydrous tetrahydrofuran were added to a 100 mL two-necked flask. Trimethylsilyl bromide (5.86 g, 38.28 mmol) was slowly added dropwise at room temperature and stirred for 24 hours. The reaction was quenched by the addition of 20 mL of anhydrous methanol and stirred for 3 hours. Finally, 300 mL of deionized water was added and stirred for 24 hours. The reaction mixture was filtered and washed with water. The filter cake was redissolved in tetrahydrofuran, precipitated in petroleum ether, and filtered. This reaction was repeated three times to obtain BCZ-C4P3OH as a white solid in a 71% yield.

[0100] The H-NMR spectrum of BCZ-C4P3OH prepared by the above method is: 1H NMR (400MHz, DMSO-d6, δ): 8.63 (s, 2H), 7.78 (m, 6H), 7.46 (m, 6H), 7.33m, 2H), 4.02 (t, J = 7.4Hz, 2H), 1.92 (d, J = 31.8Hz, 2H), 1.15 (s, 2H).

[0101] Example 5:

[0102] The non-doped hole transport material CZ-C4P2OH prepared in Example 1 was used as the hole transport layer to prepare a perovskite solar cell. Figure 5 As shown, its structure is: glass / ITO / SAM-HTL / perovskite / C 60 / BCP / Cu. The ITO conductive glass was ultrasonically cleaned with alkaline glass cleaner, deionized water, acetone and isopropyl alcohol for 30 min in sequence. After drying with nitrogen, the ITO glass was plasma cleaned for 15 min. The CZ-C4P2OH obtained in Example 1 was used as the hole transport layer, and the ethanol solution concentration was 1 mg / mL -1 After spin coating on the ITO glass surface, the excess CZ-C4P2OH on the surface was cleaned with ethanol and annealed at 100℃ for 10min. 0.1 FA 0.9 PbI3 perovskite solution was spin-coated onto the CZ-C4P2OH surface and thermally annealed at 100℃ for 30min. After cooling, 20nm C 60 Finally, an 80nm Cu layer was vacuum-evaporated as an electrode to complete the preparation of the perovskite solar cell device with an effective area of 4mm. 2 A xenon lamp solar simulator was used and the test light intensity was AM 1.5G, 100mW cm -2 The open circuit voltage, short circuit current and fill factor of the prepared battery devices were tested.

[0103] Based on the CZ-C4P2OH prepared in Example 1, a perovskite solar cell device was prepared and characterized according to the above procedure. The current-voltage (JV) characteristic curve of the cell device performance is shown in Figure 1 , where the open circuit voltage V OC is 1.147V, short-circuit current density J SC 23.31 mA / cm 2 , the filling factor FF is 0.778, and the photoelectric conversion efficiency is 20.80%.

[0104] Example 6:

[0105] The non-doped hole transport material BCZ-C4P2OH prepared in Example 2 was used as the hole transport layer to prepare a perovskite solar cell. Figure 5 As shown, its structure is: glass / ITO / SAM-HTL / perovskite / C 60 / BCP / Cu. The ITO conductive glass was ultrasonically cleaned with alkaline glass cleaner, deionized water, acetone and isopropyl alcohol for 30 min in sequence. After drying with nitrogen, the ITO glass was plasma cleaned for 15 min. The BCZ-C4P2OH obtained in Example 2 was used as the hole transport layer, and the ethanol solution concentration was 1 mg / mL -1 After spin coating on the ITO glass surface, the excess BCZ-C4P2OH on the surface was cleaned with ethanol and annealed at 100℃ for 10min. 0.1 FA 0.9 PbI3 perovskite solution was spin-coated onto the BCZ-C4P2OH surface and thermally annealed at 100℃ for 30min. After cooling, 20nm C 60 Finally, an 80nm Cu layer was vacuum-evaporated as an electrode to complete the preparation of the perovskite solar cell device with an effective area of 4mm. 2 A xenon lamp solar simulator was used and the test light intensity was AM 1.5G, 100mW cm -2 The open circuit voltage, short circuit current and fill factor of the prepared battery devices were tested.

[0106] Based on the BCZ-C4P2OH prepared in Example 2, a perovskite solar cell device was prepared and characterized according to the above procedure. The current-voltage (JV) characteristic curve of the cell device performance is shown in Figure 2 , where the open circuit voltage V OC is 1.158V, short-circuit current density J SC 23.22 mA / cm 2 , the filling factor FF is 0.782, and the photoelectric conversion efficiency is 21.02%.

[0107] Example 7:

[0108] The non-doped hole transport material CZ-C4P3OH prepared in Example 3 was used as the hole transport layer to prepare a perovskite solar cell. Figure 5 As shown, its structure is: glass / ITO / SAM-HTL / perovskite / C 60 / BCP / Cu. The ITO conductive glass was ultrasonically cleaned with alkaline glass cleaner, deionized water, acetone and isopropyl alcohol for 30 min in sequence. After drying with nitrogen, the ITO glass was plasma cleaned for 15 min. The CZ-C4P3OH obtained in Example 3 was used as the hole transport layer, and the ethanol solution concentration was 1 mg / mL -1 After spin coating on the ITO glass surface, the excess CZ-C4P3OH on the surface was cleaned with ethanol and annealed at 100℃ for 10min. 0.1 FA 0.9 PbI3 perovskite solution was spin-coated onto the CZ-C4P3OH surface and thermally annealed at 100℃ for 30min. After cooling, 20nm C 60 Finally, an 80nm Cu layer was vacuum-evaporated as an electrode to complete the preparation of the perovskite solar cell device with an effective area of 4mm. 2 A xenon lamp solar simulator was used and the test light intensity was AM 1.5G, 100mW cm -2 The open circuit voltage, short circuit current and fill factor of the prepared battery devices were tested.

[0109] Based on the CZ-C4P3OH prepared in Example 3, a perovskite solar cell device was prepared and characterized according to the above procedure. The current-voltage (JV) characteristic curve of the cell device performance is shown in Figure 3 , where the open circuit voltage V OC is 1.162V, short-circuit current density J SC 22.25 mA / cm 2 , the filling factor FF is 0.784, and the photoelectric conversion efficiency is 20.27%.

[0110] Example 8:

[0111] The non-doped hole transport material BCZ-C4P3OH prepared in Example 4 was used as the hole transport layer to prepare a perovskite solar cell. Figure 5 As shown, its structure is: glass / ITO / SAM-HTL / perovskite / C 60 / BCP / Cu. The ITO conductive glass was ultrasonically cleaned with alkaline glass cleaner, deionized water, acetone and isopropyl alcohol for 30 min in sequence. After drying with nitrogen, the ITO glass was plasma cleaned for 15 min. The BCZ-C4P3OH obtained in Example 4 was used as the hole transport layer, and the ethanol solution concentration was 1 mg / mL -1 After spin coating on the ITO glass surface, the excess BCZ-C4P3OH on the surface was cleaned with ethanol and annealed at 100℃ for 10min. 0.1 FA0.9 PbI3 perovskite solution was spin-coated onto the BCZ-C4P3OH surface and thermally annealed at 100℃ for 30min. After cooling, 20nm C 60 Finally, an 80nm Cu layer was vacuum-evaporated as an electrode to complete the preparation of the perovskite solar cell device with an effective area of 4mm. 2 A xenon lamp solar simulator was used and the test light intensity was AM 1.5G, 100mW cm -2 The open circuit voltage, short circuit current and fill factor of the prepared battery devices were tested.

[0112] Based on the BCZ-C4P3OH prepared in Example 4, a perovskite solar cell device was prepared and characterized according to the above procedure. The current-voltage (JV) characteristic curve of the cell device performance is shown in Figure 4 , where the open circuit voltage V OC is 1.164V, short-circuit current density J SC 23.58 mA / cm 2 , the filling factor FF is 0.782, and the photoelectric conversion efficiency is 21.46%.

[0113] It can be seen that when the four hole transport materials CZ-C4P2OH, BCZ-C4P2OH, CZ-C4P3OH and BCZ-C4P3OH involved in the present invention are applied to perovskite solar cells, they can obtain photoelectric conversion efficiencies of 20.80%, 21.02%, 20.27% and 21.46% respectively without doping, and have broad application prospects.

[0114] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A self-assembled monolayer hole transport material based on an alkyl polyphosphate anchor group, characterized in that: It has the following structural formula: or or or 。 2. A method for synthesizing the self-assembled monolayer hole transport material according to claim 1, characterized in that: The steps include: Step 1: Carbazole (CZ) reacts with 1,3-dibromopropane to obtain 9-(3-bromopropyl)-carbazole (CZ-C3Br): ； Step 2: CZ-C3Br and tetraethyl methylene diphosphate react to obtain (4-(9-carbazolyl)butyl-1,1-diyl)diphosphonic acid tetraethyl ester (CZ-C4P2OR): ； Step 3: CZ-C4P2OR is hydrolyzed to obtain (4-(9-carbazolyl)butyl-1,1-diyl)bisphosphonic acid (CZ-C4P2OH): 。 3. A method for synthesizing the self-assembled monolayer hole transport material according to claim 1, characterized in that: The steps include: Step 1: 3,6-diphenylcarbazole (BCZ) and 1,3-dibromopropane react to obtain 3,6-diphenyl-9-(3-bromopropyl)-carbazole (BCZ-C3Br): ； Step 2: BCZ-C3Br and tetraethyl methylene diphosphate react to obtain (4-(3,6-diphenyl-9-carbazolyl)butyl-1,1-diyl)diphosphonic acid tetraethyl ester (BCZ-C4P2OR): ； Step 3: BCZ-C4P2OR is hydrolyzed to obtain (4-(3,6-diphenyl-9-carbazolyl)butyl-1,1-diyl)bisphosphonic acid (BCZ-C4P2OH): 。 4. A method for synthesizing the self-assembled monolayer hole transport material according to claim 1, characterized in that: The steps include: Step 1: CZ-C4P2OR reacts with diethylphosphite chloride to obtain hexaethyl (4-(9-carbazolyl)butyl-1,1,1-triyl)triphosphonate (CZ-C4P3OR): ； Step 2: CZ-C4P3OR is hydrolyzed to obtain (4-(9-carbazolyl)butyl-1,1,1-triyl)triphosphonic acid (CZ-C4P3OH): 。 5. A method for synthesizing the self-assembled monolayer hole transport material according to claim 1, characterized in that: The steps include: Step 1: BCZ-C4P2OR reacts with diethylphosphite chloride to obtain (4-(3,6-diphenyl-9-carbazolyl)butyl-1,1,1-triyl)triphosphonic acid hexaethyl ester (BCZ-C4P3OR): ； Step 2: BCZ-C4P3OR is hydrolyzed to obtain (4-(3,6-diphenyl-9-carbazolyl)butyl-1,1,1-triyl)triphosphonic acid (BCZ-C4P3OH): 。 6. The method for synthesizing a self-assembled monolayer hole transport material according to claim 2 or 3, characterized in that: In step 1, the strong base used in the reaction is potassium hydroxide; the phase transfer catalyst used in the reaction is tetrabutylammonium bromide; the reaction temperature is 0-90°C; in step 2, the reaction is carried out under nitrogen or argon protection; the strong base used in the reaction is sodium hydride; the reaction solvent is tetrahydrofuran; the reaction temperature is 0-70°C; in step 3, the reaction is carried out under nitrogen or argon protection; the reaction solvent is tetrahydrofuran; the reaction temperature is 0-50°C; the hydrolysis reagent used in the reaction is trimethylsilyl bromide; and the quenching reagent used in the reaction is methanol.

7. The method for synthesizing a self-assembled monolayer hole transport material according to claim 4 or 5, characterized in that: In step 1, the strong base used in the reaction is sodium bis(trimethylsilyl)amide; the oxidant used in the reaction is hydrogen peroxide; the reaction solvent is tetrahydrofuran; and the reaction temperature is 0-50°C; in step 2, the reaction is carried out under nitrogen or argon protection; the reaction solvent is tetrahydrofuran; the reaction temperature is 0-50°C; the hydrolysis reagent used in the reaction is trimethylsilyl bromide; and the quenching reagent used in the reaction is methanol.

8. A use of the self-assembled monolayer hole transport material according to claim 1, characterized in that: The self-assembled monolayer hole transport material based on alkyl polyphosphate anchoring groups is applied to inverted perovskite solar cells.

9. The use of the self-assembled monolayer hole transport material according to claim 8, characterized in that: In the perovskite solar cell structure, a perovskite solution is spin-coated onto the surface of a self-assembled monolayer hole transport material.

10. The use of the self-assembled monolayer hole transport material according to claim 8, characterized in that: The structure of the perovskite solar cell is glass / ITO / SAM-HTL / perovskite / C60 / BCP / Cu from bottom to top, and the SAM-HTL is a self-assembled monolayer hole transport material based on an alkyl polyphosphate anchoring group.

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