Perovskite thin film passivation material and preparation method and application thereof

Abstract

The invention provides a perovskite thin film passivation material as well as a preparation method and application thereof. The perovskite thin film passivation material has a structure as shown in a general formula I, ; the perovskite thin film passivation material provided by the invention is prepared through simple and efficient nucleophilic substitution and quaternization reaction, has the characteristics of low cost, easiness in processing, efficient defect passivation and enhanced charge transfer, and can be applied to a perovskite photovoltaic cell as an efficient perovskite thin film passivation material; defect state density can be reduced, carrier lifetime can be prolonged, charge transmission performance can be enhanced, ion migration and interface recombination loss can be inhibited, and energy conversion efficiency and long-term stability of the device can be enhanced. The passivation material is suitable for various types of perovskite photovoltaic cells.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic cell material technology, and relates to a perovskite thin film passivation material, its preparation method and application. Background Technology

[0002] In the field of perovskite photovoltaics, improving the quality and stability of perovskite thin films is a key challenge for achieving high-performance and long-life devices. Perovskite materials, especially metal halide perovskites, have attracted widespread attention in the field of solar cells due to their excellent photoelectric properties, such as high light absorption coefficient, tunable band gap, and high carrier mobility. However, the ionic properties of perovskite materials make them highly sensitive to environmental factors such as humidity, oxygen, and heat, easily leading to decomposition and a rapid decline in device performance. Furthermore, grain boundaries and surface defects in perovskite films can become nonradiative recombination centers, further reducing the efficiency and stability of photovoltaic devices. To address these issues, researchers have proposed various strategies, including the use of passivation materials to improve the quality and stability of perovskite films. The role of passivation materials is to reduce nonradiative recombination by binding to defect sites in the perovskite material, thereby improving the open-circuit voltage and short-circuit current of the device. Currently, common passivation materials include small organic molecules, polymers, and inorganic materials. Organic small-molecule passivating materials, such as amines and carboxylic acids, can passivate defects by interacting with uncoordinated ions (such as Pb2+ and I-) on the surface or grain boundaries of perovskites to form coordination or ionic bonds. However, the passivation effect of traditional organic small-molecule passivating materials is limited, and they are prone to migration within perovskite films, leading to poor long-term stability. Polymer passivating materials, such as polyethyleneimine (PEI) and polymethyl methacrylate (PMMA), can improve device stability by forming a protective layer on the surface of perovskite films, preventing the erosion of moisture and oxygen. Furthermore, polymers can also passivate by binding to perovskite defect sites. However, the electrical insulation properties of polymer passivating materials may hinder carrier transport, affecting device efficiency. Inorganic passivating materials, such as metal oxides and metal sulfides, exhibit good stability and passivation effects. They can form a passivation layer by chemically reacting with perovskite defect sites, reducing non-radiative recombination. However, the preparation process of inorganic passivating materials is complex and can easily introduce new defects.

[0003] Quaternary ammonium salts, as organic salts with good ionic stability and surface activity, have shown potential in the perovskite photovoltaic field. Some studies have shown that quaternary ammonium salts can passivate defects and improve device performance by binding to anionic defects on the perovskite surface. However, traditional quaternary ammonium salt passivation materials typically have only a single function, making it difficult to simultaneously meet the charge transport and stabilization requirements of perovskite thin films. Therefore, developing novel, efficient, and multifunctional perovskite passivation materials, especially those capable of simultaneously passivating surface and grain boundary defects and improving the stability of perovskite thin films, remains a research hotspot in the perovskite photovoltaic field. In particular, a novel passivation material based on bispyridinealkylpiperazine quaternary ammonium salts possesses a unique molecular structure that gives it stronger coordination ability and better stability, promising higher performance and longer lifetime in perovskite photovoltaic devices. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a perovskite thin film passivation material, its preparation method, and its applications. The passivation material of this invention is a bispyridine alkylpiperazine quaternary ammonium salt perovskite thin film passivation material, which has the advantage of effectively passivating defects in perovskite thin films and improving the performance of perovskite photovoltaic devices. This passivation material achieves defect passivation by coordinating the quaternary ammonium salt cation with dangling ions on the perovskite surface, thereby reducing surface nonradiative recombination. Simultaneously, the bispyridine group can interact with iodine vacancies in the perovskite, further inhibiting ion migration. The alkylpiperazine structure helps enhance the hydrophobicity of the perovskite thin film, improving device stability. Furthermore, this passivation material can optimize the perovskite / electron transport layer interface, thereby enhancing electron transport and improving the photoelectric conversion efficiency of the device. The material of this invention solves the key problems faced by perovskite thin film passivation materials, and its application in perovskite solar cells can improve device efficiency and long-term stability.

[0005] The technical solution of the present invention is as follows: A perovskite thin film passivation material having the structure shown in general formula I: In general formula I, R is selected from C1-C8 straight-chain alkanes or C1-C8 branched alkanes, n is 1, 2, 3 or 4, and X... - For Cl - ,Br - Or I - .

[0006] According to the present invention, the preparation method of the above-mentioned perovskite thin film passivation material includes the following steps: 1) In a solvent, under alkaline heating conditions, a nucleophilic substitution reaction is carried out between bromoalkylpyridine and piperazine to obtain a bispyridinealkylpiperazine intermediate, wherein the bromoalkylpyridine has the structure shown in general formula II, and the bispyridinealkylpiperazine intermediate has the structure shown in general formula III. 2) In a solvent, under alkaline heating conditions, the bispyridine alkylpiperazine intermediate and the halo-saturated alkane undergo a quaternization reaction to obtain the perovskite thin film passivation material.

[0007] According to a preferred embodiment of the present invention, in step 1), the solvent is acetonitrile, N,N-dimethylformamide, or dimethyl sulfoxide; the volume ratio of the solvent to the molar ratio of piperazine is 1~2 mL:1 mmol; The alkali is sodium carbonate, potassium carbonate, sodium hydroxide or sodium hydride, and the molar ratio of the alkali to piperazine is 2~4:1; The molar ratio of the bromoalkylpyridine to piperazine is 2 to 4:1.

[0008] According to a preferred embodiment of the present invention, in step 1), the temperature of the nucleophilic substitution reaction is 50-100 °C. o C, the nucleophilic substitution reaction takes 6 to 24 hours; The post-processing steps of the reaction solution obtained after the nucleophilic substitution reaction of brominated alkylpyridine and piperazine are as follows: Ethyl acetate and water are added to the obtained reaction solution, and the organic phase obtained after separation is washed with water, dried and the solvent is removed. The crude product is purified by silica gel column chromatography with petroleum ether and ethyl acetate in a volume ratio of 3~5:1. After concentration and drying, the bispyridine alkylpiperazine intermediate is obtained.

[0009] According to a preferred embodiment of the present invention, in step 2), the solvent is N,N-dimethylformamide or dimethyl sulfoxide; the volume ratio of the solvent to the molar number of the bispyridinealkylpiperazine intermediate is 3~5 mL:1 mmol; The base is sodium carbonate, potassium carbonate, sodium hydroxide or sodium hydride, and the molar ratio of the base to the dipyridinealkylpiperazine intermediate is 3~6:1; The molar ratio of the halo-saturated alkane to the bispyridine alkylpiperazine intermediate is 2 to 4:1.

[0010] According to a preferred embodiment of the present invention, in step 2), the temperature of the quaternization reaction is 80-100°C. o C, the quaternization reaction takes 1 to 5 hours; The post-processing steps of the reaction solution obtained after the quaternization reaction of the bispyridine alkylpiperazine intermediate and the halo-saturated alkane are as follows: Dichloromethane and water are added to the obtained reaction solution. After separation, the organic phase is washed with water, dried, and the solvent is removed. The crude product is purified by silica gel column chromatography. The eluent is dichloromethane and methanol in a volume ratio of 20~100:1. After concentration and drying, perovskite thin film passivation material is obtained.

[0011] The synthetic route of this invention is as follows: In the above formula, in general formula I, R is selected from C1~C8 straight-chain alkanes or C1~C8 branched alkanes, n is 1, 2, 3 or 4, and X - For Cl - ,Br - Or I - .

[0012] According to the present invention, the perovskite thin film passivation material described above and the perovskite thin film passivation material prepared by the above preparation method are applied to perovskite solar cells.

[0013] According to a preferred embodiment of the present invention, the perovskite thin film passivation material is used as a passivation interface layer in a perovskite solar cell.

[0014] According to a preferred embodiment of the present invention, the specific preparation method of the passivation interface layer is as follows: a perovskite thin-film passivation material is dissolved in an alcohol solvent, and the passivation interface layer of the perovskite solar cell is prepared by solution processing; the alcohol solvent is isopropanol, sec-butanol, and fluorinated isopropanol; the thickness of the passivation interface layer prepared from the perovskite thin-film passivation material is 5-20 nm; and the perovskite material of the perovskite solar cell is a ternary cationic perovskite material FA. 0.80 MA 0.13 Cs 0.07 PbI 0.27 Br 0.13 .

[0015] The perovskite thin film passivation material of this invention is used as a surface passivation material. It can reduce defect state density, improve carrier lifetime, enhance charge transport performance, and suppress ion migration and interfacial recombination loss, thereby significantly improving the energy conversion efficiency and long-term stability of perovskite photovoltaic cells. It can also be used to prepare perovskite photovoltaic cells with different perovskite materials.

[0016] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects: 1. This invention ingeniously utilizes the unique structure of bispyridine alkylpiperazine quaternary ammonium salt to successfully develop a highly efficient perovskite thin film passivation material, solving the long-standing problems of grain boundary defects and ion migration in perovskite photovoltaic devices. Through precise control and optimization of alkyl chain length, quaternary ammonium salt substituents, and pyridine ring modification, the obtained passivation material can effectively passivate defects on the surface of perovskite thin films, reduce non-radiative recombination, and thus significantly improve the photoelectric conversion efficiency and stability of the device.

[0017] 2. The bispyridinealkylpiperazine quaternary ammonium salt passivation material of the present invention exhibits excellent solubility and dispersibility, enabling it to be uniformly coated on the surface of perovskite thin films to form a dense passivation layer. Its unique molecular structure effectively interacts with defect sites in the perovskite lattice, inhibiting ion migration and reducing the decomposition of the perovskite thin film under light and high temperatures. Furthermore, this passivation material can improve the surface morphology of the perovskite thin film, enhancing its uniformity and density, thereby further improving device performance.

[0018] 3. Compared with traditional perovskite thin-film passivation materials, the bispyridine alkylpiperazine quaternary ammonium salt passivation material of this invention exhibits higher passivation efficiency, better stability, and wider applicability. It can not only effectively improve the performance of small-area perovskite solar cells but also be applied to the fabrication of large-area perovskite modules, demonstrating enormous commercial application potential. Furthermore, the synthesis process of this passivation material is simple and inexpensive, facilitating large-scale production and application. Therefore, it is a highly promising passivation material for perovskite photovoltaic devices. Attached Figure Description

[0019] Figure 1 The current-voltage (JV) curve of the perovskite solar cell prepared by the perovskite thin film passivation material in Example 1 is shown.

[0020] Figure 2 The graph shows the external quantum efficiency (EQE) of the perovskite solar cell prepared using the perovskite thin film passivation material in Example 1.

[0021] Figure 3 The efficiency-time device stability curve of the perovskite solar cell prepared by the perovskite thin film passivation material in Example 1 is shown. Detailed Implementation

[0022] The embodiments of the present invention are described in detail below with reference to the technical solutions and accompanying drawings. It should be noted that the present invention is illustrated by the following examples but is not limited thereto. Unless otherwise stated, all parts and percentages are by weight. In addition, the solvents and small molecule intermediates used in the following examples were purchased from Anhui Zesheng Technology Co., Ltd. (Annaiji Chemical) and were used directly without further purification before use.

[0023] Example 1 Preparation of perovskite thin film passivation material Ia The reaction route is shown below: That is, in general formula I, R is ethane, n is 2, and X... - For Br - .

[0024] The preparation method of passivation material Ia is as follows: Bromoethylpyridine IIa (5.4 g, 29.02 mmol), piperazine (1 g, 11.61 mmol), and potassium carbonate (4.81 g, 34.83 mmol) were added to the reactor, with N,N-dimethylformamide (11.7 mL) as the solvent. o The reaction was heated at C for 12 hours; the reaction was stopped, 20 mL of ethyl acetate and 10 mL of water were added, the mixture was separated, and the resulting organic phase was washed with 10 mL of water. Anhydrous magnesium sulfate was added to the organic phase, and the solvent was removed by rotary evaporation. The crude product was purified by silica gel column chromatography with petroleum ether:ethyl acetate = 4:1, v / v. After concentration and drying, a pale yellow solid was obtained, which was 2.79 g of bispyridine ethylpiperazine intermediate IIIa, yield: 81%. HRMS: Calcd for C 18 H 24 N4, 296.2001 [M - ], found 296.1998.

[0025] Bispyridine ethylpiperazine intermediate IIIa (1 g, 3.37 mmol), bromoethane (0.76 mL, 10.12 mmol), and potassium carbonate (1.86 g, 13.49 mmol) were added to a reactor, with N,N-dimethylformamide (15.6 mL) as the solvent. 80 o The reaction was heated at C for 3 hours; the reaction was stopped, 20 mL of dichloromethane and 10 mL of water were added, the mixture was separated, and the resulting organic phase was washed with 10 mL of water. Anhydrous magnesium sulfate was added to the resulting organic phase for drying, and the solvent was removed by rotary evaporation. The crude product was purified by silica gel column chromatography with dichloromethane:methanol = 50:1, v / v as the eluent. After concentration and drying, a pale yellow solid was obtained, which was 1.50 g of perovskite film passivation material Ia, yield: 86%. HRMS: Calcd for C 22 H 34 Br2N4, 512.1150 [M - ], found512.1130.

[0026] Example 2 Preparation of perovskite thin film passivation material Ib The reaction route is shown below: That is, in general formula I, R is ethane, n is 2, and X... - For I - .

[0027] The preparation method of passivating material Ib is as follows: Bispyridine ethylpiperazine intermediate IIIa (1 g, 3.37 mmol), iodoethane (0.95 mL, 11.81 mmol), and potassium carbonate (2.33 g, 16.87 mmol) were added to a reactor, with N,N-dimethylformamide (16.9 mL) as the solvent. 90 o The reaction was heated at C for 5 hours; the reaction was stopped, 20 mL of dichloromethane and 10 mL of water were added, the mixture was separated, and the resulting organic phase was washed with 10 mL of water. Anhydrous magnesium sulfate was added to the organic phase for drying, and the solvent was removed by rotary evaporation. The crude product was purified by silica gel column chromatography with dichloromethane:methanol = 50:1, v / v as the eluent. After concentration and drying, a yellow solid was obtained, which was 1.73 g of perovskite film passivation material Ib, yield: 84%. HRMS: Calcd for C 22 H 34 I2N4, 608.0873 [M - ], found 608.0815.

[0028] Example 3 Preparation of perovskite thin film passivation material Ic The reaction route is shown below: That is, in general formula I, R is propane, n is 2, and X... - For Br - .

[0029] The preparation method of passivation material Ic is as follows: Bispyridine ethylpiperazine intermediate IIIa (1 g, 3.37 mmol), bromopropane (1.23 mL, 13.49 mmol), and potassium carbonate (2.80 g, 20.24 mmol) were added to a reactor, with dimethyl sulfoxide (14.4 mL) as the solvent. 100 oThe reaction was heated at C for 4 hours; the reaction was stopped, 20 mL of dichloromethane and 10 mL of water were added, the mixture was separated, and the resulting organic phase was washed with 10 mL of water. Anhydrous magnesium sulfate was added to the organic phase for drying, and the solvent was removed by rotary evaporation. The crude product was purified by silica gel column chromatography with dichloromethane:methanol = 100:1, v / v as the eluent. After concentration and drying, a yellow solid was obtained, which was 2.16 g of perovskite film passivation material (Ic), yield: 87%. HRMS: Calcd for C 24 H 38 Br2N4, 540.1463 [M - ], found 540.1413.

[0030] Example 4 Preparation of perovskite thin film passivation material Id The reaction route is shown below: That is, in general formula I, R is ethane, n is 1, and X... - For Br - .

[0031] The preparation method of passivation material Id is as follows: Bromomethylpyridine IIb (5.99 g, 34.83 mmol), piperazine (1 g, 11.61 mmol), and sodium carbonate (4.92 g, 46.44 mmol) were added to the reactor, with N,N-dimethylformamide (17.9 mL) as the solvent. o The reaction was heated at C for 18 hours; the reaction was stopped, 20 mL of ethyl acetate and 10 mL of water were added, the mixture was separated, and the resulting organic phase was washed with 10 mL of water. Anhydrous magnesium sulfate was added to the organic phase, and the solvent was removed by rotary evaporation. The crude product was purified by silica gel column chromatography with petroleum ether:ethyl acetate = 5:1, v / v, yielding a concentrated and dried pale yellow solid, which was 2.59 g of bispyridine methylpiperazine intermediate IIIb, yield: 83%. HRMS: Calcd for C 16 H 20 N4, 268.1688 [M - ], found 268.1671.

[0032] Bispyridine methylpiperazine intermediate IIIb (1 g, 3.73 mmol), bromoethane (0.83 mL, 11.18 mmol), and sodium hydride (0.60 g, 60%, 14.91 mmol) were added to a reactor, with N,N-dimethylformamide (14.4 mL) as the solvent. 90 oThe reaction was heated at C for 4 hours; the reaction was stopped, 20 mL of dichloromethane and 10 mL of water were added, the mixture was separated, and the resulting organic phase was washed with 10 mL of water. Anhydrous magnesium sulfate was added to the resulting organic phase, and the solvent was removed by rotary evaporation. The crude product was purified by silica gel column chromatography with dichloromethane:methanol = 50:1, v / v as the eluent. After concentration and drying, a yellow solid was obtained, which was 1.62 g of perovskite film passivation material (Id), yield: 89%. HRMS: Calcd for C 20 H 30 Br2N4, 484.0837 [M - ], found484.0812.

[0033] Example 5 Preparation of perovskite thin film passivation material Ie The reaction route is shown below: That is, in general formula I, R is ethane, n is 3, and X... - For Br - .

[0034] The preparation method of passivation material Ie is as follows: Bromopropylpyridine IIc (5.81 g, 29.02 mmol), piperazine (1 g, 11.61 mmol), and sodium hydride (1.86 g, 60%, 46.44 mmol) were added to the reactor, with acetonitrile (11.8 mL) as the solvent. o The reaction was heated at C for 12 hours; the reaction was stopped, 20 mL of ethyl acetate and 10 mL of water were added, the mixture was separated, and the resulting organic phase was washed with 10 mL of water. Anhydrous magnesium sulfate was added to the organic phase, and the solvent was removed by rotary evaporation. The crude product was purified by silica gel column chromatography with petroleum ether:ethyl acetate = 3:1, v / v. After concentration and drying, a pale yellow solid was obtained, which was 3.24 g of bispyridinepropylpiperazine intermediate IIIc, yield: 86%. HRMS: Calcd for C 20 H 28 N4, 324.2314 [M - ], found 324.2301.

[0035] Bispyridinepropylpiperazine intermediate IIIc (1 g, 3.08 mmol), bromoethane (0.92 mL, 12.32 mmol), and sodium hydroxide (0.74 g, 18.48 mmol) were added to a reactor, with N,N-dimethylformamide (11.88 mL) as the solvent. 100 oThe reaction was heated at C for 3 hours; the reaction was stopped, 20 mL of dichloromethane and 10 mL of water were added, the mixture was separated, and the resulting organic phase was washed with 10 mL of water. Anhydrous magnesium sulfate was added to the resulting organic phase, and the solvent was removed by rotary evaporation. The crude product was purified by silica gel column chromatography with dichloromethane:methanol = 50:1, v / v as the eluent. After concentration and drying, a yellow solid was obtained, which was 1.35 g of perovskite film passivation material Ie, yield: 81%. HRMS: Calcd for C 24 H 38 Br2N4, 540.1463 [M - ], found540.1412.

[0036] Comparative Example 1 The following comparative examples illustrate in detail the technological advancements of the perovskite thin-film passivation material of the present invention compared to conventional single-functional passivation materials (such as PEAI). Phenylethyl ammonium iodide (PEAI) is used as the passivation material, whose cation contains only a single phenylethyl structure. PEAI is administered at a concentration of 20 mg / mL... -1 The concentration was dissolved in isopropanol and deposited on the surface of a perovskite film by spin coating, followed by annealing at 100°C for 10 minutes. Performance comparisons are shown in Table 1. The conclusion is that PEAI only reacts with Pb²⁺ ions. + Coordination passivation lacks the ability of the bispyridine group to capture iodine vacancies, and the short alkyl chain leads to insufficient hydrophobicity, resulting in a device efficiency (22.9%) significantly lower than that of the present invention (24.7%). Therefore, the perovskite thin film passivation material with the structure provided by the present invention exhibits significantly higher photovoltaic performance and device stability after application compared to traditional single-function passivation materials.

[0037] Experimental Example 1 The properties and applications of the perovskite thin film passivation material synthesized in this embodiment are further described in detail below. It should be noted that, since the perovskite thin film passivation materials synthesized by the method of this invention have very similar structures and properties, this invention only describes the product obtained in the preferred embodiment in detail. However, those skilled in the art, based on the description of this invention, can reasonably infer the properties and application effects of other similar products with the structural formula I claimed in this invention, which will not be repeated here.

[0038] Performance testing and application experiments of perovskite thin film passivation material Ia.

[0039] Fabrication and testing of perovskite solar cells: An inverse perovskite solar cell was fabricated with the following structure: ITO / PTAA:F4-TCNQ / perovskite-passivation material Ia / PCBM / Bphen / Ag. Indium tin oxide (ITO) and metallic silver serve as electrodes. PTAA:F4-TCNQ, passivation material Ia, PCBM, and Bphen act as the hole transport layer, passivation interface layer, electron transport layer, and hole blocking layer, respectively. The perovskite layer is FA. 0.80 MA 0.13 Cs 0.07 PbI 0.27 Br 0.13 (Ternary cation perovskite). Fabrication process of perovskite solar cells: ITO substrate is ultrasonically cleaned sequentially with ethanol, acetone, and ultrapure water; after nitrogen purging, it is treated with ozone for 15 minutes; PTAA:F4-TCNQ chlorobenzene solution is spin-coated in a nitrogen glove box to a thickness of approximately 30 nm, and annealed for 2 minutes; FA is spin-coated using the sec-butanol anti-solvent method. 0.80 MA 0.13 Cs 0.07 PbI 0.27 Br 0.13 The precursor solution (a 0.87:0.13 v / v mixture of DMF and NMP) was spin-coated to a thickness of approximately 700 nm; the passivation material Ia was coated with an isopropanol solution to a thickness of 5-20 nm; the PCBM chlorobenzene solution was spin-coated to a thickness of 70-100 nm; and the Bphen isopropanol solution was spin-coated to a thickness of 5-10 nm. The spin-coated substrate was then transferred into a vacuum evaporation chamber, where a vacuum level of 1×10⁻⁶ was achieved. -4 At Pa, a silver electrode (100 nm) is deposited by vapor deposition.

[0040] Battery performance testing methods and procedures: All batteries were unsealed and their performance was tested in a nitrogen-filled glove box. After obtaining the batteries, their performance was tested. JV The curve and the EQE curve, i.e. Figure 1 and Figure 2 The subsequent test will determine the efficiency and stability curves of the battery. Figure 3 .in JV The curves were measured using a Zolix Solar IV-150A-ZZU system, with a photocurrent of 100 mW / cm². -2 Light intensity was measured using a Zolix-HPS-300XA solar simulator at AM 1.5G illuminance, and calibrated using a Zolix QE-B1 silicon-based solar cell. External quantum efficiency (EQE) spectra were measured using a Zolix SCS10-X150-DSSC-ZZU system.

[0041] Depend on Figures 1 to 3It can be seen that the passivation material Ia, as the perovskite passivation interface layer, enables perovskite solar cells to have excellent passivation performance. Compared with existing passivation materials reported in the literature, passivation material Ia can simultaneously maintain a high open-circuit voltage and fill factor, which stems from the strong coordination effect and good electron transport performance of passivation material Ia.

[0042] In addition, Table 1 lists the performance parameters of the control devices and the passivation material Ia passivated perovskite solar cells.

[0043] Table 1 As shown in Table 1, perovskite solar cells passivated with passivation material Ia exhibit excellent photovoltaic performance and stability. Furthermore, it reduces defect state density, increases carrier lifetime, enhances charge transport performance, and suppresses ion migration and interfacial recombination losses. This type of passivation material addresses key issues faced by perovskite thin-film passivation materials, and its application in perovskite solar cells can improve device efficiency and long-term stability.

Claims

1. A perovskite thin film passivation material, characterized in that, The perovskite thin film passivation material has the structure shown in general formula I: In general formula I, R is selected from C1-C8 straight-chain alkanes or C1-C8 branched alkanes, n is 1, 2, 3 or 4, and X... - For Cl - ,Br - Or I - .

2. A method for preparing a perovskite thin film passivation material according to claim 1, characterized in that, Includes the following steps: 1) In a solvent, under alkaline heating conditions, a nucleophilic substitution reaction is carried out between bromoalkylpyridine and piperazine to obtain a bispyridinealkylpiperazine intermediate, wherein the bromoalkylpyridine has the structure shown in general formula II, and the bispyridinealkylpiperazine intermediate has the structure shown in general formula III. 2) In a solvent, under alkaline heating conditions, the bispyridine alkylpiperazine intermediate and the halo-saturated alkane undergo a quaternization reaction to obtain the perovskite thin film passivation material.

3. The method for preparing the perovskite thin film passivation material according to claim 2, characterized in that, In step 1), the solvent is acetonitrile, N,N-dimethylformamide, or dimethyl sulfoxide; the volume ratio of the solvent to the molar amount of piperazine is 1~2 mL:1 mmol. The alkali is sodium carbonate, potassium carbonate, sodium hydroxide or sodium hydride, and the molar ratio of the alkali to piperazine is 2~4:1; The molar ratio of the bromoalkylpyridine to piperazine is 2 to 4:

1.

4. The method for preparing the perovskite thin film passivation material according to claim 2, characterized in that, In step 1), the temperature of the nucleophilic substitution reaction is 50~100°C. o C, the nucleophilic substitution reaction takes 6 to 24 hours; The post-processing steps of the reaction solution obtained after the nucleophilic substitution reaction of brominated alkylpyridine and piperazine are as follows: Ethyl acetate and water are added to the obtained reaction solution, and the organic phase obtained after separation is washed with water, dried and the solvent is removed. The crude product is purified by silica gel column chromatography with petroleum ether and ethyl acetate in a volume ratio of 3~5:

1. After concentration and drying, the bispyridine alkylpiperazine intermediate is obtained.

5. The method for preparing the perovskite thin film passivation material according to claim 2, characterized in that, In step 2), the solvent is N,N-dimethylformamide or dimethyl sulfoxide; the volume ratio of the solvent to the molar number of the bispyridinealkylpiperazine intermediate is 3~5 mL:1 mmol; The base is sodium carbonate, potassium carbonate, sodium hydroxide or sodium hydride, and the molar ratio of the base to the dipyridinealkylpiperazine intermediate III is 3~6:1; The molar ratio of the halo-saturated alkane to the bispyridine alkylpiperazine intermediate is 2 to 4:

1.

6. The method for preparing the perovskite thin film passivation material according to claim 2, characterized in that, In step 2), the temperature of the quaternization reaction is 80~100°C. o C, the quaternization reaction takes 1 to 5 hours; The post-processing steps of the reaction solution obtained after the quaternization reaction of the bispyridine alkylpiperazine intermediate and the halo-saturated alkane are as follows: Dichloromethane and water are added to the obtained reaction solution. After separation, the organic phase is washed with water, dried, and the solvent is removed. The crude product is purified by silica gel column chromatography. The eluent is dichloromethane and methanol in a volume ratio of 20~100:

1. After concentration and drying, perovskite thin film passivation material is obtained.

7. The application of the perovskite thin film passivation material according to claim 1 or the perovskite thin film passivation material prepared by any one of claims 2 to 6 in perovskite solar cells.

8. The application according to claim 7, characterized in that, The perovskite thin film passivation material is used to form a passivation interface layer in a perovskite solar cell.

9. The application according to claim 8, characterized in that, The specific preparation method of the passivation interface layer is as follows: The perovskite thin-film passivation material is dissolved in an alcohol solvent, and the passivation interface layer of the perovskite solar cell is prepared by solution processing. The alcohol solvent is isopropanol, sec-butanol, and fluorinated isopropanol. The thickness of the passivation interface layer prepared from the perovskite thin-film passivation material is 5-20 nm. The perovskite material of the perovskite solar cell is a ternary cationic perovskite material FA. 0.80 MA 0.13 Cs 0.07 PbI 0.27 Br 0.13 .

Images