Self-assembled monolayer materials with asymmetric central core and methods of making and use

Abstract

The application discloses a kind of self-assembled monolayer materials with asymmetric intermediate core and method and application, belong to solar cell field.The self-assembled monolayer material described above is combined with phosphonic acid, sulfonic acid and other anchoring groups using asymmetric intermediate core, with good hydrophobicity and high light transmittance, can be used as hole transport layer material, for preparing p-i-n structure organic solar cell and perovskite solar cell, wherein, organic solar cell has realized 18.9% energy conversion efficiency, while showing excellent environmental stability, still maintains more than 95% of initial performance after 480h storage in air, far superior to traditional PEDOT:PSS interface layer based device.The application can significantly improve the energy conversion efficiency and environmental stability of solar cell by designing and developing a series of self-assembled monolayer materials with asymmetric intermediate core.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of solar cells, and particularly relates to a self-assembled monolayer material with an asymmetric intermediate core, a preparation method and application thereof. BACKGROUND

[0002] Solar energy is a clean and renewable energy, and the use of solar cells to generate electricity is an effective way to solve the current energy crisis and environmental pollution. As early as 1954, Bell Laboratories developed the first silicon solar cell in history. Up to now, although silicon solar cells have occupied a considerable market share, their production cost is relatively high, and the power conversion efficiency (PCE) is increasingly approaching the theoretical limit. Therefore, it is urgent to develop a new generation of low-cost and high-efficiency photovoltaic technology. Organic solar cells (OSCs) have attracted more and more attention from researchers due to their intrinsic flexibility, light weight, and low processing cost. In the past decade, the PCE of OSCs has developed rapidly and has reached 19.2% certified by the National Renewable Energy Laboratory.

[0003] OSCs can be divided into p-i-n structure and n-i-p structure according to the polarity of the electrode. The p-i-n structure of OSC is composed of an indium tin oxide (ITO) substrate, a hole transport layer (HTL), an active layer, an electron transport layer (ETL), and a metal electrode (Ag), etc. in turn, wherein the hole transport layer is mainly responsible for transporting photo-generated holes and blocking photo-generated electrons, and plays an important role in device efficiency and stability. At present, the commonly used hole transport layer material for p-i-n structure OSC is poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), but it has the following problems: (1) PEDOT:PSS has strong acidity, which can corrode the ITO substrate, thereby causing In 3+ intrusion into the hole transport layer and even the active layer, which seriously damages the device performance; (2) PEDOT:PSS has high hygroscopicity, which can absorb water and oxygen in the air and accelerate device aging; (3) under the action of light, heat and other external pressure, phase separation easily occurs, which leads to gradual degradation of device performance. Therefore, it is crucial to design and develop a low-cost, high-performance, and active layer-compatible HTL material for further improvement of the efficiency and stability of OSCs.

[0004] Self-assembled monolayers (SAMs) can be anchored on the ITO surface by dehydration condensation of anchor groups (such as phosphonic acid group, sulfonic acid group, boric acid group, carboxyl group, etc.) with the hydroxyl group on the surface of the ITO substrate to form a uniform monolayer, which is expected to improve the running stability of the corresponding device. SAMs can adjust the work function of ITO, optimize the energy level arrangement between ITO and the active layer, thereby effectively extracting holes; and have high light transmittance, which helps to obtain higher short-circuit current and achieve higher PCE. In addition, SAMs have low synthesis cost, small amount, and are easy to prepare, which has great potential in practical production. The above advantages prompt more and more researchers to focus on the design and development of SAMs. It is worth noting that the SAMs commonly used in current organic photovoltaic devices are mostly based on symmetric intermediate core structures. These SAMs have a small dipole moment and exhibit poor hole extraction ability, thereby affecting the device performance. Therefore, the development of SAMs based on asymmetric intermediate core structures is expected to improve the hole extraction ability and further improve the device efficiency. SUMMARY

[0005] The purpose of the present application is to provide a self-assembled monolayer material with an asymmetric intermediate core, which has a simple synthesis method, low cost and is easy to mass-produce. The second purpose of the present application is to provide a method for preparing the self-assembled monolayer material with an asymmetric intermediate core. The third purpose of the present application is to provide an application of the self-assembled monolayer material with an asymmetric intermediate core.

[0006] TECHNICAL SOLUTION The self-assembled monolayer material with an asymmetric intermediate core provided by the present application has the following structure:

[0007] wherein X is H, Br, Cl or F;

[0008] The general formula of the self-assembled monolayer material is:

[0009] wherein n is 1-3, and R is a phosphonic acid group, a sulfonic acid group, a boric acid group or a carboxylic acid group.

[0010] Preferably, the self-assembled monolayer material comprises (2-(11H-benzo[a]carbazol-11-yl)ethyl)phosphonic acid, which has the following structure: (2-(5,8-dibromo-11H-benzo[a]carbazol-11-yl)ethyl)phosphonic acid, which has the following structure: (2-(3H-benzo[e]indol-3-yl)ethyl)phosphonic acid, which has the following structure: and (2-(7-bromo-3H-benzo[e]indol-3-yl)ethyl)phosphonic acid, which has the following structure:

[0011] The method for preparing the self-assembled monolayer material with asymmetric intermediate core, wherein n is 2, and R is phosphonic acid group, comprises the following steps:

[0012] (1) dissolving the compound of formula (I) and sodium hydride in a solvent, stirring the reaction mixture at room temperature under a protective atmosphere, adding 2-bromoethyl diethyl phosphate, and heating the reaction mixture; After the reaction is completed, the obtained reaction mixture is subjected to solvent removal, and the organic phase is extracted with ethyl acetate, and then dried with a water removal agent, and then subjected to vacuum distillation to obtain a crude product;

[0013] (2) dissolving the crude product in a reaction solvent, adding trimethylsilyl bromide, and fully reacting at room temperature under a protective atmosphere, then adding a quenching agent to continue stirring, removing part of the methanol by vacuum distillation, and then adding distilled water until the solution is not transparent, and then stirring overnight, and then filtering the product, and then washing with water and drying to obtain the product.

[0014] Further, in step (1), the solvent is dimethylformamide or tetrahydrofuran, and the heating reaction is performed at a temperature of 50-80°C for 5-15 hours.

[0015] Further, in step (1), the molar equivalent of 2-bromoethyl diethyl phosphate relative to the compound of formula (I) is 1.0-3.0 eq, and the molar equivalent of sodium hydride relative to the compound of formula (I) is 1.0-3.0 eq.

[0016] Further, in step (1), the water removal agent is anhydrous sodium sulfate or anhydrous magnesium sulfate, and the solvent removal is performed by placing the reaction mixture in a NaCl aqueous solution and fully mixing.

[0017] Further, in step (2), the reaction solvent is anhydrous dichloromethane, 1,4-dioxane or tetrahydrofuran, the molar equivalent of trimethylsilyl bromide relative to the crude product is 10-15 eq, and the quenching agent is methanol.

[0018] The self-assembled monolayer material with asymmetric intermediate core is used in the preparation of a p-i-n structure organic solar cell and a perovskite solar cell.

[0019] Further, the p-i-n structure organic solar cell and the perovskite solar cell sequentially comprise, from bottom to top, a metal oxide electrode, a hole transport layer, an active layer, an electron transport layer and a top electrode, and the material used in the hole transport layer is the self-assembled monolayer material with asymmetric intermediate core.

[0020] Further, the preparation steps of the solar cell are as follows:

[0021] ​​(a) The cleaned ITO glass is treated with UV-ozone to improve wettability as a metal oxide electrode;

[0022] (b) An isopropanol solution containing the self-assembled monolayer material with asymmetric intermediate core is prepared;

[0023] (c) The solution is spin-coated onto the ITO substrate and annealed;

[0024] (d) The active layer solution, PNDIT-F3N solution are spin-coated in turn and annealed to obtain the active layer and electron transport layer;

[0025] (e) Finally, the Ag top electrode is deposited by thermal evaporation; wherein, in step (a), the UV-ozone treatment time is 10-20 min; in step (b), the molar concentration of the self-assembled monolayer material with asymmetric intermediate core is 0.1-0.8 mg / mL, preferably 0.3-0.5 mg / mL; in step (c), the spin-coating speed is 1000-5000 r.p.m, preferably 3000-5000 rpm; the duration is 15-50 s, preferably 30-50 s; in step (e), the thickness of the Ag electrode is 10-100 nm, preferably 70-100 nm.

[0026] Invention principle: The asymmetric intermediate core structure often has a larger dipole moment than the common symmetric intermediate core structure, and the larger dipole moment helps to improve the hole extraction ability. Therefore, designing SAMs material based on asymmetric intermediate core structure helps to further improve the energy conversion efficiency of solar cells.

[0027] Beneficial effects: Compared with the commonly used hole transport layer material (3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS) of existing organic solar cells, the SAMs based on asymmetric intermediate core structure prepared as a hole transport layer material has significant advantages in many aspects: (1) The SAMs based on asymmetric intermediate core structure absorbs less light in the near-infrared region, which allows the active layer to receive more photons to occur exciton dissociation, thereby improving PCE; (2) PEDOT:PSS has strong acidity and can corrode the ITO substrate, resulting in In 3+Intrusion into the hole transport layer or even the active layer can severely damage the device performance. However, SAMs based on the asymmetric intermediate core structure are chemically stable and do not cause the above problems. (3) PEDOT:PSS has high hygroscopicity and easily absorbs water and oxygen from the air, which accelerates the aging of the device. In contrast, SAMs based on the asymmetric intermediate core structure have good hydrophobicity, which can greatly improve the water and oxygen stability of the device. Therefore, OSCs prepared by using SAMs based on the asymmetric intermediate core structure as HTLs have significantly improved efficiency and stability compared to devices prepared by PEDOT:PSS. The development of these novel small molecule materials not only effectively improves the performance of OSCs, but also provides important inspiration for reducing the production cost of OSCs and promoting their commercialization. Attached Figure Description

[0028] Figure 1 The hydrogen nuclear magnetic resonance spectrum of BACz prepared in Example 1 of this invention;

[0029] Figure 2 The carbon NMR spectrum of BACz prepared in Example 1 of this invention;

[0030] Figure 3 The 1H NMR spectrum of 2Br-BACz prepared in Example 2 of this invention;

[0031] Figure 4 The carbon NMR spectrum of 2Br-BACz prepared in Example 2 of this invention;

[0032] Figure 5 The 1H NMR spectrum of BEId prepared in Example 3 of this invention;

[0033] Figure 6 The carbon NMR spectrum of BEId prepared in Example 3 of this invention;

[0034] Figure 7 The 1H NMR spectrum of Br-BEId prepared in Example 4 of this invention;

[0035] Figure 8 The carbon NMR spectrum of Br-BEId prepared in Example 5 of this invention;

[0036] Figure 9 The graph shows the performance test results of different organic solar cells prepared in Example 5;

[0037] Figure 10 The image shows the water contact angle test results for different hole transport layer materials prepared in Example 5. Detailed Implementation

[0038] The present invention will now be further described in conjunction with specific embodiments and accompanying drawings.

[0039] Example 1

[0040] The synthesis of self-assembled monolayer material (2-(11H-benzo[a]carbazol-11-yl)ethyl)phosphonic acid (BACz) provided by the present example includes the following two steps:

[0041] (1) Synthesis of compound diethyl (2-(11H-benzo[a]carbazol-11-yl)ethyl)phosphonate:

[0042] Dissolve 11H-benzo[a]carbazole (0.5 g, 2.30 mmol) in 10 mL of dimethylformamide, cool to 0 °C, slowly add sodium hydride (92.1 mg, 2.30 mmol), stir at room temperature for 30 min, then slowly drop diethyl 2-bromoethylphosphonate (0.56 g, 2.30 mmol) and raise the temperature to 70 °C for overnight reaction. After the reaction is completed, cool to room temperature, pour the reaction mixture into an aqueous NaCl solution, extract with ethyl acetate. Then dry the organic phase with anhydrous sodium sulfate, then distill under reduced pressure to obtain the crude product. Purify the crude product by silica gel column chromatography (solvent polarity, petroleum ether: ethyl acetate = 1:2) to obtain diethyl (2-(11H-benzo[a]carbazol-11-yl)ethyl)phosphonate (0.68 g, 77%) as a light yellow solid. 1 HNMR (400 MHz, CDC13): 8.54 (d, J = 8.5 Hz, 1H), 8.16 (t, 2H), 8.05 (d, J = 6.7 Hz, 1H), 7.68 (d, J = 8.5 Hz, 1H), 7.64-7.59 (m, 2H), 7.56-7.49 (m, 2H), 7.33 (t, 1H), 5.14-5.09 (m, 2H), 4.26-4.12 (m, 4H), 2.50-2.42 (m, 2H), 1.40-1.37 (m, 6H). 13 CNMR (125 MHz, CDC13): 139.75, 133.88, 133.64, 129.79, 125.83, 125.05, 124.72, 123.31, 122.12, 121.43, 121.06, 120.02, 119.77, 119.67, 119.17, 108.88, 62.08, 62.01, 40.13, 27.37, 16.56, 16.50.

[0043] The reaction formula is as follows:

[0044]

[0045] (2) Synthesis of compound (2-(11H-benzo[a]carbazol-11-yl)ethyl)phosphonic acid:

[0046] Diethyl (2-(11H-benzo[a]carbazol-11-yl)ethyl)phosphonate (0.5 g, 1.31 mmol) was dissolved in 10 mL of dichloromethane, and trimethylsilyl bromide (2.01 g, 13.1 mmol) was added dropwise slowly. The reaction was allowed to proceed overnight at room temperature. After the reaction was complete, as indicated by a spot test, methanol was added and stirring was continued for 10 min. Distilled water was then added dropwise until the solution was no longer clear. The product was filtered off and oven dried to give (2-(11H-benzo[a]carbazol-11-yl)ethyl)phosphonic acid as a white solid (0.29 g, 67%). 1 HNMR (400 MHz, DMSO-d6): 8.63 (d, J = 8.4 Hz, 1H), 8.31-8.25 (m, 2H), 8.12 (d, J = 6.7 Hz, 1H), 7.74-7.64 (m, 3H), 7.60 (t, 1H), 7.53 (t, 1H), 7.31 (t, 1H), 5.04-5.00 (m, 2H), 2.28-2.09 (m, 2H). 13 CNMR (125 MHz, DMSO-d6): 139.87, 133.85, 133.61, 129.91, 126.45, 125.57, 125.36, 122.92, 122.17, 122.01, 121.05, 120.26, 120.23, 119.79, 119.21, 109.74, 40.65, 29.77. MALDI-TOF-MS m / z: [M-H] - calcd. for C 18 H 16 NO3P, 324.0789; found, 324.0794.

[0047] The reaction is as follows:

[0048]

[0049] Example 2

[0050] The synthesis of self-assembled monolayer material (2-(5,8-dibromo-11H- benzo[a]carbazol-11-yl)ethyl)phosphonic acid (2Br-BACz) provided in this example includes the following two steps:

[0051] (1) Synthesis of diethyl (2-(5,8-dibromo-11H-benzo[a]carbazol-11-yl)ethyl)phosphonate:

[0052] To a solution of 5,8-dibromo-11H-benzo[a]carbazole (0.5 g, 1.33 mmol) in 10 mL of dimethylformamide, sodium hydride (53.3 mg, 1.33 mmol) was added slowly at 0 °C, and the reaction mixture was stirred at room temperature for 30 min. Then, diethyl 2-bromoethylphosphonate (0.33 g, 1.33 mmol) was added dropwise, and the reaction mixture was heated at 70 °C overnight. After the reaction was completed, the reaction mixture was cooled to room temperature, and poured into an aqueous NaCl solution. The organic layer was separated, dried over anhydrous sodium sulfate, and distilled under reduced pressure to obtain a crude product. The crude product was purified by column chromatography on silica gel (solvent polarity, petroleum ether: ethyl acetate = 1:2) to obtain diethyl (2-(5,8-dibromo-11H-benzo[a]carbazol-11-yl)ethyl)phosphonate (0.58 g, 81%) as a yellowish solid. 1 HNMR (400 MHz, CDC13): 8.47-8.44 (m, 2H), 8.35 (s, 1H), 8.14 (d, J = 1.8 Hz, 1H), 7.66-7.59 (m, 2H), 7.55-7.52 (m, 1H), 7.42 (d, J = 8.8 Hz, 1H), 5.03-4.97 (m, 2H), 4.16-4.03 (m, 4H), 2.39-2.30 (m, 2H), 1.31-1.27 (m, 6H). 13 CNMR (125 MHz, CDC13): 138.47, 133.87, 131.11, 129.24, 128.25, 126.81, 126.31, 124.00, 123.08, 122.93, 122.36, 121.68, 119.01, 114.65, 113.35, 110.65, 62.16, 62.10, 40.37, 27.20, 16.54, 16.48.

[0053] The reaction scheme is as follows:

[0054]

[0055] (2) Synthesis of compound (2-(5,8-dibromo-11H-benzo[a]carbazol-11-yl)ethyl)phosphonic acid:

[0056] Diethyl (2-(5,8-dibromo-11H-benzo[a]carbazol-11-yl)ethyl)phosphonate (0.5 g, 0.93 mmol) was dissolved in 10 mL of dichloromethane, and trimethylsilyl bromide (1.42 g, 9.3 mmol) was added dropwise slowly. The reaction was stirred at room temperature overnight. After the reaction was completed, methanol was added and stirred for 10 min. Distilled water was added dropwise until the solution was not transparent. The product was filtered and dried to obtain white solid (2-(5,8-dibromo-11H-benzo[a]carbazol-11-yl)ethyl)phosphonic acid (0.27 g, 61%). 1 H NMR (400 MHz, DMSO-d6): 8.23 (d, J = 8.1 Hz, 1H), 7.91 (d, J = 9.6 Hz, 1H), 7.62 (t, 2H), 7.51 (t, 1H), 7.47 (d, J = 3.1 Hz, 1H), 7.38 (t, 1H), 7.05 (d, J = 3.1 Hz, 1H), 4.48-4.42 (m, 2H), 2.15-2.07 (m, 2H). 13 CNMR (125 MHz, DMSO-d6): 138.85, 134.15, 130.68, 128.56, 128.48, 127.55, 127.28, 124.25, 123.92, 123.09, 123.06, 123.00, 118.83, 113.75, 112.95, 112.24, 41.52, 29.53. MALDI-TOF-MS m / z: [M-H] - calcd. for C 18 H 14 Br2NO3P, 481.8979; found, 481.8997.

[0057] The reaction scheme is as follows:

[0058]

[0059] Example 3:

[0060] The synthesis of self-assembled monolayer material (2-(3H-benzo[e]indol-3-yl)ethyl)phosphonic acid (BEId) provided in this example includes the following three steps:

[0061] (1) Synthesis of compound 3H-benzo[e]indole:

[0062] To a solution of 2-aminonaphthalene (1 g, 6.98 mmol), Pt / Al203(0.46 g, 1.7 mol%), ZnO dispersion (77 μL, 4.5 mol%) in ethylene glycol was heated to reflux at 185 °C overnight. After the completion of the reaction, the reaction mixture was cooled to room temperature and poured into aqueous NaCl solution and extracted with dichloromethane. The organic layer was dried over anhydrous sodium sulfate and then distilled under reduced pressure to give the crude product. The crude product was purified by silica gel column chromatography (solvent polarity, petroleum ether: dichloromethane = 2: 1) to give 3H-benzo[e]indole (0.95 g, 81%) as a white flocculent solid. 1 HNMR (400 MHz, CDC13): 8.39 (s, 1H), 8.34 (d, J = 8.2 Hz, 1H), 8.00 (d, J = 8.1 Hz, 1H), 7.71-7.62 (m, 2H), 7.58-7.48 (m, 2H), 7.28 (t, J = 2.8 Hz, 1H), 7.17 (t, J = 2.6 Hz, 1H). 13 CNMR (125 MHz, CDC13): 132.2, 129.2, 128.6, 128.3, 125.9, 123.4, 123.1, 123.0, 122.8, 122.3, 112.8, 101.9.

[0063] The reaction scheme is as follows:

[0064]

[0065] (2) Synthesis of compound (2-(3H-benzo[e]indol-3-yl)ethyl)diethyl phosphonate:

[0066] To a solution of 3H-benzo[e]indole (0.5 g, 2.99 mmol) in 10 mL of dimethylformamide was cooled to 0 °C and sodium hydride (119.6 mg, 2.99 mmol) was added slowly. The reaction mixture was stirred at room temperature for 30 min and then 2-bromoethyl diethyl phosphonate (0.73 g, 2.99 mmol) was added dropwise slowly and the reaction mixture was heated to 70 °C overnight. After the completion of the reaction, the reaction mixture was cooled to room temperature and poured into aqueous NaCl solution and extracted with ethyl acetate. The organic layer was dried over anhydrous sodium sulfate and then distilled under reduced pressure to give the crude product. The crude product was purified by silica gel column chromatography (solvent polarity, petroleum ether: ethyl acetate = 1:2) to give (2-(3H-benzo[e]indol-3-yl)ethyl)diethyl phosphonate (0.84 g, 85%) as a pale yellow liquid. 1HNMR (400 MHz, CDC13): 8.28 (d, J = 8.5 Hz, IH), 7.96 (d, J = 6.8 Hz, IH), 7.69 (d, J = 8.6 Hz, IH), 7.57-7.50 (m, 2H), 7.49-7.45 (m, IH), 7.13 (d, J = 3.0 Hz, IH), 6.61 (d, J = 3.0 Hz, 2H), 4.90-4.84 (m, 2H), 4.20-4.06 (m, 4H), 2.45-2.37 (m, 2H), 1.36-1.31 (m, 6H). 13 CNMR (125 MHz, CDC13): 131.45, 129.54, 128.56, 128.20, 126.54, 125.70, 123.39, 122.63, 121.45, 121.19, 120.20, 103.07, 62.03, 61.97, 44.50, 28.49, 16.50, 16.44.

[0067] The reaction scheme is as follows:

[0068]

[0069] (3) Synthesis of compound (2-(3H-benzo[e]indol-3-yl)ethyl)phosphonic acid:

[0070] Diethyl (2-(3H-benzo[e]indol-3-yl)ethyl)phosphonate (0.5 g, 1.51 mmol) was dissolved in 10 mL of dichloromethane, and trimethylsilyl bromide (2.31 g, 15.1 mmol) was added dropwise slowly. The reaction was allowed to proceed overnight at room temperature. After the reaction was complete, methanol was added and stirring was continued for 10 min. Distilled water was then added dropwise until the solution was not transparent. The product was filtered off and dried to obtain white solid (2-(3H-benzo[e]indol-3-yl)ethyl)phosphonic acid (0.25 g, 61%). 1 H NMR (400 MHz, DMSO-d6): 8.16 (d, J = 8.1 Hz, 2H), 7.55 (d, J = 9.6 Hz, 2H), 7.48 (t, 2H), 7.22 (t, 2H), 4.58-4.52 (m, 2H), 2.07-1.98 (m, 2H). 13 CNMR (125 MHz, DMSO-d6): 138.83, 134.12, 130.66, 128.46, 127.53, 127.26, 123.9, 122.97, 118.81, 113.72, 112.93, 112.22, 41.49, 29.5. MALDI-TOF-MS m / z: [M-H] - calcd. for C14 H 14 NO3P, 274.0632; found, 274.0637.

[0071] The reaction scheme is as follows:

[0072]

[0073] Example 4: This example provides the synthesis of self-assembled monolayer material (2-(7-bromo-3H-benzo[e]indol-3-yl)ethyl)phosphonic acid (Br-BEId) includes the following three steps:

[0074] (1) Synthesis of compound 7-bromo-3H-benzo[e]indole:

[0075] 6-bromo-2-aminonaphthalene (1 g, 4.50 mmol), Pt / Al203(0.30 g, 1.7 mol%), ZnO dispersion (50 μL, 4.5 mol%) were dissolved in ethylene glycol and heated to reflux at 185 °C overnight. After the completion of the reaction, the reaction mixture was cooled to room temperature and poured into aqueous NaCl solution and extracted with dichloromethane. The organic phase was then dried over anhydrous sodium sulfate and distilled under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography (solvent polarity, petroleum ether: dichloromethane = 4: 1) to obtain 7-bromo-3H-benzo[e]indole (0.76 g, 84%) as a white flocculent solid. 1 HNMR (400 MHz, CDC13): 8.39 (s, 1H), 8.34 (d, J = 8.2 Hz, 1H), 8.00 (d, J = 8.1 Hz, 1H), 7.71-7.62 (m, 2H), 7.58-7.48 (m, 2H), 7.28 (t, J = 2.8 Hz, 1H), 7.17 (t, J = 2.6 Hz, 1H). 13 CNMR (125 MHz, CDC13): 132.2, 129.2, 128.6, 128.3, 125.9, 123.4, 123.1, 123.0, 122.8, 122.3, 112.8, 101.9.

[0076] The reaction scheme is as follows:

[0077]

[0078] (2) Synthesis of compound diethyl (2-(7-bromo-3H-benzo[e]indol-3-yl)ethyl)phosphonate:

[0079] Dissolve 7-bromo-3H-benzo[e]indol (0.5 g, 2.03 mmol) in 10 mL of dimethylformamide, cool to 0 °C, slowly add sodium hydride (81.26 mg, 2.03 mmol), stir at room temperature for 30 min, then slowly add diethyl 2-bromoethylphosphonate (0.50 g, 2.03 mmol), and raise the temperature to 70 °C overnight. After the reaction is complete, cool to room temperature, pour the reaction mixture into aqueous NaCl, and extract with ethyl acetate. Dry the organic phase over anhydrous sodium sulfate, then distill under reduced pressure to obtain the crude product. Purify the crude product by silica gel column chromatography (solvent polarity, petroleum ether: ethyl acetate = 1:2) to obtain diethyl (2-(7-bromo-3H-benzo[e]indol-3-yl)ethyl)phosphonate (0.63 g, 75%) as a light yellow liquid. 1 HNMR (400 MHz, CDC13): 8.17 (d, J = 8.7 Hz, IH), 8.08 (d, J = 2.0 Hz, IH), 7.63-7.60 (m, IH), 7.56-7.52 (m, 2H), 7.23 (d, J = 3.1 Hz, IH), 7.01 (d, J = 3.1 Hz, IH), 4.55-4.50 (m, 2H), 4.10-4.03 (m, 4H), 2.36-2.28 (m, 2H), 1.30-1.26 (m, 6H). 13 CNMR (125 MHz, CDC13): 133.08, 131.37, 130.57, 128.96, 127.78, 126.02, 124.67, 123.37, 121.75, 116.76, 111.87, 101.08, 62.02, 61.96, 40.79, 28.43, 16.43, 16.37.

[0080] The reaction scheme is as follows:

[0081]

[0082] (3) Synthesis of compound (2-(7-bromo-3H-benzo[e]indol-3-yl)ethyl)phosphonic acid:

[0083] Dissolve diethyl (2-(7-bromo-3H-benzo[e]indol-3-yl)ethyl)phosphonate (0.5 g, 1.22 mmol) in 10 mL of dichloromethane, slowly add trimethylsilyl bromide (1.87 g, 12.2 mmol), and stir at room temperature overnight. After the reaction is complete, add methanol and stir for 10 min, then add distilled water until the solution is not transparent, filter the product, and dry to obtain (2-(7-bromo-3H-benzo[e]indol-3-yl)ethyl)phosphonic acid (0.27 g, 63%) as a white solid. 1HNMR (400 MHz, CDC13): 8.08-8.04 (m, 2H), 7.61-7.58 (m, IH), 7.53-7.50 (m, 2H), 7.21 (d, J = 3.1 Hz, IH), 6.99 (d, J = 3.1 Hz, IH), 4.55-4.50 (m, 2H), 2.36-2.28 (m, 2H). 13 CNMR (125 MHz, CDC13): 132.06, 130.51, 130.34, 128.88, 126.85, 126.02, 124.67, 123.60, 121.75, 116.76, 111.87, 101.08, 40.79, 28.43. MALDI-TOF-MS m / z: [M-H] - calcd. For C 14 H 13 BrNO3P, 351.9737; found, 351.9743.

[0084] The reaction scheme is as follows:

[0085]

[0086] Example 5

[0087] The four kinds of SAMs based on asymmetric intermediate core structure prepared in Examples 1-4 were used as hole transport layers, and a p-i-n structure organic solar cell was prepared, the structure of which was metal oxide electrode, hole transport layer, organic active layer, electron transport layer and metal electrode from bottom to top.

[0088] The specific preparation steps are as follows:

[0089] (a) The ITO glass was sequentially cleaned with cleaning solution, deionized water, acetone and isopropanol under ultrasonic for 15 min, and then dried in a vacuum oven. The dried ITO glass was treated with ultraviolet-ozone for 15 min to improve wettability; the SAMs based on asymmetric intermediate core structure were dissolved in isopropanol at a concentration of 0.5 mg / mL and stirred for 30 min. After stirring was completed, 40 μL of the SAMs solution based on asymmetric intermediate core structure was spin-coated on the ITO substrate at a rotation speed of 3000 r.p.m. for 30 s, and annealed on a hot stage at 100°C for 10 min to prepare a hole transport layer;

[0090] (b) Weigh PM6 and Y6 according to the ratio of PM6:Y6 = 1:1 (mass ratio), then dissolve them in chloroform at a concentration of 14 mg / mL and stir for 30 min. After stirring, spin-coat 15 μL of the active layer solution onto SAMs based on the asymmetric intermediate core structure, spin-coat at a speed of 3000 r.pm for 30 s, and then anneal at 80 °C for 5 min on a hot plate to prepare the active layer.

[0091] (c) PDIN was dissolved in ultra-dry methanol at a concentration of 0.5 mg / mL and stirred for 30 min. After stirring, 40 μL of PDIN solution was spin-coated onto the active layer, and then spin-coated at 3000 rpm for 30 s to prepare the electron transport layer. Finally, a 120 nm thick Ag electrode was thermally deposited onto the prepared film.

[0092] The structures of the four SAMs products based on asymmetric intermediate core structures prepared in Examples 1-4 were determined using nuclear magnetic resonance (NMR), and the results are as follows: Figures 1-8 As shown.

[0093] The fabricated organic photovoltaic device was tested using a xenon lamp solar simulator (test light source intensity: AM 1.5G, 100mW cm⁻¹). -2 The obtained JV curve is as follows: Figure 9 As shown in A), the PCE of the four SAMs based on asymmetric intermediate core structures are 18.0%, 18.1%, 18.6%, and 18.9%, respectively, all higher than the 17.7% efficiency of the 2PACz device based on a symmetric intermediate core structure. Furthermore, the fabricated SAMs based on asymmetric intermediate core structures retain over 95% of their initial efficiency after 480 hours of storage in air. Figure 9 The values ​​of B) represent 95.0%, 96.4%, 95.9%, and 96.7% of the initial efficiency, respectively. In contrast, the efficiency of the PEDOT:PSS-based device stored under the same conditions decreased to 34.0% of the initial efficiency after 360 hours of storage. These results demonstrate that the four novel SAMs based on asymmetric intermediate core structures significantly improve both device efficiency and stability compared to PEDOT:PSS.

[0094] Hydrophobicity of SAMs based on asymmetric intermediate core structure was tested using a contact angle meter. Figure 10), it can be seen from the water contact angle diagram that the water contact angles of ITO / BEId, ITO / Br-BEId, ITO / BACz and ITO / 2Br-BACz are 61.44°, 71.26°, 72.12°, 79.54° respectively, which are significantly higher than that of ITO / PEDOT:PSS (25.59°). Therefore, the four kinds of SAMs based on asymmetric intermediate core structure prepared in Example 1-Example 4 can endow the ITO electrode with good hydrophobicity, thereby helping to improve the stability of the device.

Claims

1. A self-assembled monolayer material with an asymmetric intermediate core, characterized in that, The general formula for the self-assembled monolayer material is: (II); where X is H, Br, Cl or F, n is 1-3, and R is a phosphonic acid group, sulfonic acid group, boric acid group or carboxylic acid group.

2. The self-assembled monolayer material according to claim 1, characterized in that, The self-assembled monolayer material comprises (2-(3H-benzo[e]indol-3-yl)ethyl)phosphonic acid, with the structural formula: And (2-(7-bromo-3H-benzo[e]indol-3-yl)ethyl)phosphonic acid, with the structural formula: .

3. A method for preparing a self-assembled monolayer material with an asymmetric intermediate core as described in claim 1, characterized in that, Where n is 2, R is a phosphonic acid group, and the preparation steps are as follows: (1) Sodium hydride was dissolved in a solvent and stirred at room temperature under a protective atmosphere. The reaction was carried out, and then 2-bromoethyl phosphate diethyl ester was added and heated to react. After the reaction was completed, the solvent was removed from the resulting reaction mixture, the organic phase was extracted with ethyl acetate, and then the organic phase was dried with a dehydrating agent and distilled under reduced pressure to obtain the crude product. (2) Dissolve the crude product in the reaction solvent, add trimethylbromosilane dropwise, and react fully at room temperature under a protective atmosphere. After the reaction is complete, add a quencher and continue stirring. Remove some methanol by vacuum distillation, then add distilled water dropwise until the solution is opaque. Stir overnight, filter out the product, wash with water, and dry to obtain the final product.

4. The manufacturing method according to claim 3, characterized in that, In step (1), the solvent is dimethylformamide or tetrahydrofuran, and the conditions for the heating reaction are: reaction temperature of 50-80℃ and reaction time of 5-15h.

5. The manufacturing method according to claim 3, characterized in that, In step (1), the 2-bromoethyl phosphate diethyl ester is relative to The molar equivalent is 1.0-3.0 eq, and the sodium hydride is relative to The molar equivalent is 1.0-3.0 eq.

6. The manufacturing method according to claim 3, characterized in that, In step (1), the dehydrating agent is anhydrous sodium sulfate or anhydrous magnesium sulfate, and the solvent removal method is to place the reaction mixture in an aqueous NaCl solution and mix thoroughly.

7. The manufacturing method according to claim 3, characterized in that, In step (2), the reaction solvent is anhydrous dichloromethane, 1,4-dioxane or tetrahydrofuran, and the molar equivalent of trimethylbromosilane relative to the crude product is 10-15 eq; the quencher is methanol.

8. The application of a self-assembled monolayer material with an asymmetric intermediate core as described in any one of claims 1-2 in the fabrication of pin-structured organic solar cells and perovskite solar cells.

9. The application according to claim 8, characterized in that, The organic solar cell and perovskite solar cell with pin structure include, from bottom to top: a metal oxide electrode, a hole transport layer, an active layer, an electron transport layer and a top electrode. The material used for the hole transport layer is the self-assembled monolayer material with an asymmetric intermediate core as described in claim 1.

10. The application according to claim 9, characterized in that, The battery is prepared in the following steps: (a) The cleaned ITO glass was treated with ultraviolet-ozone to improve wettability and used as a metal oxide electrode; (b) Prepare an isopropanol solution containing the self-assembled monolayer material with an asymmetric intermediate core as described in claim 1; (c) Spin-coating the above solution onto an ITO substrate and annealing it; (d) The active layer solution and PNDIT-F3N solution were spin-coated and annealed sequentially to obtain the active layer and the electron transport layer; (e) Finally, Ag is deposited by thermal evaporation to form the top electrode; wherein, in step (a), the UV-ozone treatment time is 10-20 min; in step (b), the molar concentration of the self-assembled monolayer material with the asymmetric intermediate core is 0.1-0.8 mg / mL; in step (c), the spin coating speed is 1000-5000 rpm and the duration is 15-50 s; in step (e), the thickness of the Ag electrode is 10-100 nm.

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