Perovskite thin film and preparation method thereof

Abstract

The invention provides a perovskite thin film and a preparation method thereof, and belongs to the technical field of perovskite thin films, and the preparation method comprises the following steps: S1, preparing modified octa (aminophenyl trioxosilane); s2, preparing a precursor solution; and S3, spin-coating the pretreated substrate with the precursor solution, dropwise adding ethyl acetate at the same time, performing illumination treatment under ultraviolet light, and then immediately performing micro-vibration and curing annealing on the substrate to obtain the perovskite thin film. According to the perovskite thin film obtained by the invention, the purposes of synchronously increasing the open-circuit voltage and the filling factor of a solar cell, improving the photoelectric conversion efficiency and enhancing the long-term stability can be achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of perovskite thin films, and in particular to a perovskite thin film and a preparation method thereof. BACKGROUND

[0002] Perovskite solar cells (PSCs) have become a research hotspot of new generation photovoltaic technology due to their excellent photoelectric conversion efficiency, low raw material cost and convenient solution preparation process. The quality of the photoactive layer, i.e. the perovskite thin film, especially the crystallinity, coverage and defect density, directly determines the final performance and stability of the cell. An ideal high-efficiency cell requires the perovskite thin film to have large grains, high purity, low pinhole density and good interface contact, so as to promote the efficient separation and extraction of photo-generated carriers and inhibit non-radiative recombination. However, the thin film prepared by the traditional one-step spin coating method often has a too fast and uncontrollable crystallization process, is prone to form a porous and uneven morphology, and is accompanied by a large number of grain boundaries and bulk defects, which seriously restricts the further improvement of the cell efficiency and affects the operation stability.

[0003] In order to optimize the quality of the perovskite thin film, the prior art generally adopts the method of adding additives to the precursor solution, and the commonly used additives are metal cations and organic molecules, which can improve the quality of the thin film to a certain extent, but there are limitations in simultaneously realizing crystallization guidance, defect passivation and long-term stability improvement.

[0004] The patent document with the publication number CN116406208A discloses a perovskite thin film, a preparation method thereof and a perovskite thin film optoelectronic device. The scheme is to immerse the lead iodide thin film into a heated anisole solution or isopropanol solution for the first time to obtain a mesoporous lead iodide thin film, and then coat an organic cation solution on the mesoporous lead iodide thin film for the second time to obtain a perovskite thin film. Although the perovskite thin film prepared by the scheme improves the crystallization rate, it still has deficiencies in defect passivation and the like, and the photoelectric conversion efficiency of the cell prepared from the thin film is not high.

[0005] Therefore, it is necessary to provide a perovskite thin film and a preparation method thereof to solve the problems existing in the prior art. SUMMARY

[0006] Therefore, the present application provides a perovskite thin film and a preparation method thereof, which can realize the simultaneous improvement of the open-circuit voltage and the fill factor of the solar cell, improve the photoelectric conversion efficiency and enhance the long-term stability.

[0007] To achieve the above-mentioned purpose, the present application provides a preparation method of a perovskite thin film, comprising the following steps: Step S1, under ice bath condition, octakis(aminophenyltrioxysilane) is added into anhydrous acetonitrile, then HI aqueous solution is slowly added dropwise, stirred uniformly, poured into anhydrous ether for precipitation, suction filtration, washing, drying, to obtain modified octakis(aminophenyltrioxysilane); Step S2, in a glove box, dimethyl sulfoxide and N,N-dimethylformamide are added into a beaker, then formamidinium hydriodide, lead iodide, chlorosulfonylisocyanate, methyl ammonium bromide, methyl ammonium chloride and urea are added in sequence, heated and stirred, then modified octakis(aminophenyltrioxysilane) is added, stirred until completely dissolved, filtered using polytetrafluoroethylene, and left to stand, to obtain a precursor solution; Step S3, the precursor solution is used for spin coating on a pretreated substrate, while ethyl acetate is added dropwise, then ultraviolet light is used for light treatment, then the substrate is immediately subjected to micro-vibration, solidification annealing, to obtain a perovskite film.

[0008] Octakis(aminophenyltrioxysilane) is neutral, and is prone to agglomeration in a strong ion precursor system, has poor compatibility, and is easy to form micron-sized particles or local enrichment when directly added into the precursor system; and the -NH2 carried by octakis(aminophenyltrioxysilane) is a Lewis base, which is easy to form a strong complex with Pb 2+ in the precursor solution, disturb the crystallization kinetics, and affect crystallization; meanwhile, it can also cause deprotonation of FA / MA, and further cause uncontrollable intermediate phases and residues; in addition, the electrically neutral -NH2 mainly relies on weak hydrogen bond interaction to be adsorbed on the crystal surface or SnO2 interface, and cannot long-term and firmly "occupy" defects; the octakis(aminophenyltrioxysilane) body lacks halogen anions, and it is difficult to compensate I - vacancies.

[0009] By modifying octakis(aminophenyltrioxysilane) using HI, the overall polarity rises after protonation, and the modified octakis(aminophenyltrioxysilane) has positively charged NH 3+ I - , which can be stably dispersed in a dimethyl sulfoxide / N,N-dimethylformamide / salt environment, greatly improves the compatibility, can significantly reduce the risk of agglomeration, and the -NH 3+ no longer acts as a strong Lewis base, thereby avoiding excessive complexation and side reactions with Pb 2+ , making the crystallization more controllable and avoiding the generation of other intermediate phases. By modification, I - is also introduced, which can directly compensate I - vacancies, realizes the targeted compensation of I - vacancies; -NH 3+ is stably fixed on the grain boundary / surface defect site through electrostatic and hydrogen bond interactions, and the passivation strength is much higher than that of neutral amine. One octakis(aminophenyltrioxysilane) molecule has 8 -NH 3+ I- Anchor points can bridge adjacent grain boundaries, reduce grain boundary barriers and ion migration. The positively charged surface can form a stable hydrogen bond network with the -OH / surface defects of SnO2, improving the wettability and adhesion of the precursor solution. Modified octakis(amino phenyl trioxysilane) can make the final perovskite film more dense, uniform, and reduce pinholes and edge thick edges; and help the precursor solution to be more stable after solvent resistance and crystallization, thereby realizing the stability of short-circuit current.

[0010] Formamidinium hydriodide and lead iodide can form a perovskite main body with strong near-infrared absorption and good energy level adaptation in the precursor solution, thereby ensuring the carrier generation rate and laying the foundation for improving the short-circuit current. Methylammonium chloride can be used as a crystallization control agent, Cl - The introduction of can reduce the crystallization nucleation barrier, guide vertical growth, obtain larger grains and fewer grain boundaries, and methylammonium chloride will volatilize in the late annealing stage, avoiding changes in the band gap; part of MA + and Br - in methylammonium bromide will enter the perovskite lattice to form a mixed cation perovskite or halogen perovskite, thereby optimizing the stability of the crystal structure; methylammonium chloride and methylammonium bromide can promote the perovskite film to have lower surface and grain boundary traps, thereby reducing the recombination current, and thereby improving the open-circuit voltage and fill factor of the solar cell, and improving the photoelectric conversion efficiency.

[0011] After the spin coating of the precursor solution is completed, the micro-vibration process is used to promote the solvent-anti-solvent exchange and the external diffusion of small molecules, thereby helping to uniformize the crystal nucleus and fill the micropores, which can further reduce the surface roughness of the perovskite film, improve the interface contact effect, and thereby realize the reduction of series resistance and the improvement of fill factor; and can avoid the late phase change caused by solvent retention, and realize the improvement of long-term stability of the film.

[0012] Preferably, in the step S1, the temperature of the ice bath is 0-5℃; the concentration of the HI aqueous solution is 55-60wt%.

[0013] Preferably, in the step S2, the mass ratio of dimethyl sulfoxide and N,N-dimethylformamide is 1: (3.5-4.5).

[0014] Dimethyl sulfoxide as a strong coordination solvent forms a complex with lead iodide, delays instantaneous nucleation, and widens the spin coating process window; N,N-dimethylformamide adjusts the viscosity and volatilization rate to provide a controllable action time for anti-solvent induction.

[0015] Preferably, in the step S2, the temperature of the heating and stirring is 40-60℃, and the time is 10-20min.

[0016] Preferably, after adding the modified octakis(aminophenyltrisiloxane) and stirring until completely dissolved, triphenylsulfonium p-toluenesulfonate is also added and mixed.

[0017] Triphenylsulfonium p-toluenesulfonate can release strong acid in situ after light stimulation, accelerate the decomplexation and crystallization of the intermediate phase, thereby reducing the required annealing temperature and time, and its low acid amount and short action time do not cause halogen migration and corrosion. In addition, the acidification environment brought by triphenylsulfonium p-toluenesulfonate can convert unreacted amines into -NH 3+ state, further promoting defect passivation.

[0018] Preferably, in the step S4, the preparation of the pretreated substrate includes the following steps: ultrasonic cleaning of the substrate, nitrogen blowing dry, UV-O3 treatment, spin coating of SnO2 glue, drying, cooling to room temperature, and obtaining the pretreated substrate.

[0019] Ultrasonic cleaning, nitrogen blowing dry, and ultraviolet ozone treatment of the substrate can significantly remove organic contamination and introduce hydroxyl groups on the substrate surface, improving its surface energy and wettability, making the subsequent spin coating of tin dioxide colloid denser and without pinholes. After spin coating and drying of tin dioxide, its conduction band position matches that of the lead iodide-based perovskite, enabling selective contact that is electron-friendly and hole-blocking.

[0020] Preferably, the spin coating speed is 2700-3200 rpm, and the time is 25-40 s.

[0021] Preferably, in the step S3, the spin coating includes a first segment spin coating and a second segment spin coating, the time of the first segment spin coating is 8-12 s, and the time of the second segment spin coating is 18-22 s.

[0022] The first segment low-speed spin coating realizes the spreading and leveling of the precursor solution, and the second segment high-speed spin coating with dropwise addition of ethyl acetate can rapidly reduce the solubility and dielectric constant, achieve uniform supersaturation on the substrate, form a dense solvated intermediate phase and lock the morphology, which helps to reduce pinholes and edge accumulation of the thin film.

[0023] Preferably, in the step S3, the wavelength of the ultraviolet light is 365-405 nm, and the frequency of the micro-vibration is 35-45 kHz.

[0024] To achieve the above-mentioned purposes, the application also provides a perovskite thin film prepared by the above-mentioned method for preparing a perovskite thin film, and the precursor solution includes the following raw materials in weight percentage: Dimethyl sulfoxide 6.6 parts, N,N-dimethylformamide 23.1-29.7 parts, formamidine hydroiodide 8.653 parts, lead iodide 25.632 parts, chlorosulfonyl isocyanate 1.08 parts, methylammonium bromide 0.18 parts, methylammonium chloride 0.7 parts, urea 0.15 parts, and modified octakis(aminophenyltrioxysilane) 0.07 parts.

[0025] The perovskite thin film prepared by the preparation method of the application can realize synchronous improvement of open-circuit voltage and fill factor of a solar cell, improve photoelectric conversion efficiency, and enhance long-term stability.

[0026] The above technical solution of the application at least has the following beneficial effects: 1. By modifying octakis(aminophenyltrioxysilane) with HI, the compatibility and dispersion of octakis(aminophenyltrioxysilane) are effectively improved, defects are passivated, the final perovskite thin film is more dense and uniform, pinholes and edge thick edges are reduced, and the crystallization of the precursor solution after anti-solvent is more stable, thereby realizing stable short-circuit current of the solar cell.

[0027] 2. Methylammonium chloride and methylammonium bromide can promote the perovskite thin film to have lower surface and grain boundary traps, thereby reducing recombination current, improving open-circuit voltage and fill factor of the solar cell, and meanwhile, uniform crystallization is beneficial to stable short-circuit current of the solar cell.

[0028] 3. The use of micro-vibration process can homogenize crystal nuclei and fill micropores, further reduce the surface roughness of the perovskite thin film, thereby reducing the series resistance of the solar cell and improving the fill factor, and can avoid late phase change caused by solvent retention, thereby improving the long-term stability of the thin film. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a scanning electron microscope image of the perovskite thin film prepared in Example 1 of the application; Figure 2 It is a scanning electron microscope image of the perovskite thin film prepared in Example 3 of the application; Figure 3 It is a scanning electron microscope image of the perovskite thin film prepared in Example 5 of the application. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the application clearer, the technical solution of the embodiments of the application will be described clearly and completely below in combination with the embodiments of the application. The described embodiments are part of the embodiments of the application, and all other embodiments obtained by those skilled in the art based on the described embodiments of the application belong to the scope of protection of the application.

[0031] Example 1 The substrate was ultrasonically cleaned, dried with nitrogen, treated with UV-O3 for 15 min, spin-coated with SnO2 glue at a speed of 3000 rpm for 35 s, dried at 150 ℃ for 30 min, and cooled to room temperature to obtain a pretreated substrate.

[0032] A dry three-necked flask was taken, 2.5 mL of anhydrous acetonitrile was added, 0.1 g of octakis(aminophenyltrisiloxane) was added under the condition of 0-5 ℃ ice bath, and then 0.1 mL of 55 wt% HI aqueous solution was slowly added dropwise. After stirring at room temperature for 25 min, it was precipitated in anhydrous ether, filtered, washed, and dried at 40 ℃ under vacuum for 12 h to obtain modified octakis(aminophenyltrisiloxane).

[0033] In the glove box, 0.66 g of dimethyl sulfoxide and 2.97 g of N,N-dimethylformamide were added to a beaker, followed by the addition of 865.3 mg of formamidinium iodide, 2563.2 mg of lead iodide, 108 mg of chlorosulfonyl isocyanate, 18 mg of methylammonium bromide, 70 mg of methylammonium chloride, and 15 mg of urea. The mixture was heated to 50 ℃ and stirred for 15 min. Then 7 mg of modified octakis(aminophenyltrisiloxane) was added and stirred until completely dissolved. 10 mg of triphenylsulfonium p-toluenesulfonate was added, and the mixture was filtered using a 0.45 µm PTFE filter. After standing for 40 min, a precursor solution was obtained.

[0034] The pretreated substrate was spin-coated with the precursor solution in two stages. The first stage was spin-coated at a speed of 1000 rpm for 10 s, and the second stage was spin-coated at a speed of 3000 rpm for 20 s. At the same time, 0.2 mL of ethyl acetate was added dropwise at the 12th second of the second stage. After 5 s of adding ethyl acetate, the substrate was irradiated with ultraviolet light at a wavelength of 365-405 nm and an intensity of 15 mW·cm -2 After the irradiation was completed, the substrate was subjected to micro-vibration at a frequency of 40 kHz, an equivalent acceleration of 0.2G, and a time of 20 s. Then the substrate was placed on a hot plate and heated to 110 ℃ for 25 min to obtain a perovskite film.

[0035] Example 2 The substrate was ultrasonically cleaned, dried with nitrogen, treated with UV-O3 for 15 min, spin-coated with SnO2 glue at a speed of 2700 rpm for 40 s, dried at 150 ℃ for 30 min, and cooled to room temperature to obtain a pretreated substrate.

[0036] A dry three-necked flask was taken and 5 mL of anhydrous acetonitrile was added thereto, 0-5 ℃ ice bath condition, 0.2 g of octakis(aminophenyltrioxysilane) was added, then 0.2 mL of 58 wt% HI aqueous solution was slowly added dropwise, stirred at room temperature for 25 min, precipitated into anhydrous ether, suction filtered, washed, and vacuum dried at 40 ℃ for 12 h to obtain modified octakis(aminophenyltrioxysilane).

[0037] In the glove box, 0.66 g of dimethyl sulfoxide and 2.97 g of N,N-dimethylformamide were added to a beaker, then 865.3 mg of formamidine hydroiodide, 2563.2 mg of lead iodide, 108 mg of chlorosulfonyl isocyanate, 18 mg of methylammonium bromide, 70 mg of methylammonium chloride, and 15 mg of urea were added in sequence, heated to 40 ℃, stirred for 20 min, then 7 mg of modified octakis(aminophenyltrioxysilane) was added, stirred until completely dissolved, 12 mg of triphenylsulfonium p-toluenesulfonate was added, after mixing, filtered using 0.45 µm PTFE, and stood for 40 min to obtain a precursor solution.

[0038] The pretreated substrate was subjected to two-stage spin coating using the precursor solution, the first-stage spin coating speed was 1000 rpm, and the time was 12 s, the second-stage spin coating speed was 3000 rpm, and the time was 18 s, while 0.22 mL of ethyl acetate was added dropwise at the 12th s of the second-stage spin coating, 5 s after the addition of ethyl acetate, ultraviolet light with a wavelength of 365-405 nm and an intensity of 15 mW·cm -2 was used for light treatment for 15 s, after the completion of the light treatment, the substrate was subjected to micro-vibration with a parameter of 45 kHz, an equivalent acceleration of 0.2G, and a time of 20 s, then the substrate was placed on a hot plate and heated to 110 ℃ for 25 min to obtain a perovskite film.

[0039] Example 3 The substrate was subjected to ultrasonic cleaning, nitrogen blowing, UV-O3 treatment for 15 min, spin coating of SnO2 glue with a spin coating speed of 3200 rpm and a time of 25 s, then drying at 150 ℃ for 30 min, and cooling to room temperature to obtain a pretreated substrate.

[0040] A dry three-necked flask was taken and 5 mL of anhydrous acetonitrile was added thereto, 0-5 ℃ ice bath condition, 0.2 g of octakis(aminophenyltrioxysilane) was added, then 0.2 mL of 58 wt% HI aqueous solution was slowly added dropwise, stirred at room temperature for 25 min, precipitated into anhydrous ether, suction filtered, washed, and vacuum dried at 40 ℃ for 12 h to obtain modified octakis(aminophenyltrioxysilane).

[0041] In a glove box, 0.66 g of dimethyl sulfoxide and 2.31 g of N,N-dimethylformamide were added to a beaker, followed by the addition of 865.3 mg of formamidine hydroiodide, 2563.2 mg of lead iodide, 108 mg of chlorosulfonyl isocyanate, 18 mg of methylammonium bromide, 70 mg of methylammonium chloride, and 15 mg of urea, heated to 60°C, stirred for 10 min, then 7 mg of modified octakis(aminophenyltrisiloxane) was added, stirred until completely dissolved, 8 mg of triphenylsulfonium p-toluenesulfonate was added, after mixing, filtered using a 0.45 μm PTFE, and left to stand for 40 min to obtain a precursor solution.

[0042] The pretreated substrate was spin-coated with the precursor solution in two stages, the first stage at a speed of 1000 rpm for 8 s, and the second stage at a speed of 3000 rpm for 22 s, while 0.18 mL of ethyl acetate was added dropwise at the 12th s of the second stage, and after 5 s of adding the ethyl acetate, the substrate was irradiated with ultraviolet light at a wavelength of 365-405 nm and an intensity of 15 mW·cm -2 The substrate was then placed on a hot plate and heated to 110°C for 25 min to anneal the perovskite film.

[0043] Example 4 The substrate was ultrasonically cleaned, dried with nitrogen, and treated with UV-O3 for 15 min. SnO2 paste was spin-coated at a speed of 2900 rpm for 35 s, and then baked at 150°C for 30 min to obtain a pretreated substrate.

[0044] A dry three-necked flask was taken and 2.5 mL of anhydrous acetonitrile was added thereto. Under the condition of an ice bath at 0-5°C, 0.1 g of octakis(aminophenyltrisiloxane) was added, and then 0.1 mL of an HI aqueous solution with a concentration of 60 wt% was slowly added dropwise. After stirring at room temperature for 20 min, the product was precipitated in anhydrous diethyl ether, filtered, washed, and dried at 40°C under vacuum for 12 h to obtain modified octakis(aminophenyltrisiloxane).

[0045] In a glove box, 0.66 g of dimethyl sulfoxide and 2.31 g of N,N-dimethylformamide were added to a beaker, followed by the addition of 865.3 mg of formamidine hydroiodide, 2563.2 mg of lead iodide, 108 mg of chlorosulfonyl isocyanate, 18 mg of methylammonium bromide, 70 mg of methylammonium chloride, and 15 mg of urea, heated to 45°C, stirred for 20 min, then 7 mg of modified octakis(aminophenyltrisiloxane) was added, stirred until completely dissolved, 10 mg of triphenylsulfonium p-toluenesulfonate was added, after mixing, filtered using a 0.45 μm PTFE, and left to stand for 40 min to obtain a precursor solution.

[0046] The pre-treatment substrate was subjected to two-stage spin coating with the precursor solution, the first stage spin coating speed was 1000 rpm, the time was 10 s, the second stage spin coating speed was 3000 rpm, the time was 20 s, while the second stage spin coating was added 0.18 mL of ethyl acetate at the 12th s, after adding ethyl acetate for 5 s, the substrate was subjected to light treatment under the ultraviolet light with the wavelength of 365-405 nm and the light intensity of 15 mW·cm -2 After the light treatment was completed, the substrate was subjected to micro-vibration immediately, the parameters were 45 kHz, the equivalent acceleration was 0.2G, and the time was 20 s, then the substrate was placed on the hot plate and heated to 110℃ for 25 min to obtain the perovskite film.

[0047] Example 5 The substrate was subjected to ultrasonic cleaning, nitrogen blowing dry, UV-O3 treatment for 15 min, spin coating SnO2 glue, the spin coating speed was 3200 rpm, the time was 30 s, then drying at 150℃ for 30 min, and cooling to room temperature to obtain the pre-treatment substrate.

[0048] A dry three-necked flask was taken, 5 mL of anhydrous acetonitrile was added, 0-5℃ ice bath was added, 0.2 g of octakis(aminophenyltrisiloxane) was added, then 0.2 mL of 55wt% HI aqueous solution was slowly added, stirred at room temperature for 25 min, precipitated in anhydrous ether, suction filtered, washed, and vacuum dried at 40℃ for 12 h to obtain modified octakis(aminophenyltrisiloxane).

[0049] In the glove box, 0.66 g of dimethyl sulfoxide and 2.97 g of N,N-dimethylformamide were added to a beaker, then 865.3 mg of formamidinium hydriodide, 2563.2 mg of lead iodide, 108 mg of chlorosulfonyl isocyanate, 18 mg of methylammonium bromide, 70 mg of methylammonium chloride and 15 mg of urea were added in turn, heated to 40℃, stirred for 20 min, then 7 mg of modified octakis(aminophenyltrisiloxane) was added, stirred until completely dissolved, 8 mg of triphenylsulfonium p-toluenesulfonate was added, after mixing, filtered with 0.45µm PTFE, and stood for 40 min to obtain the precursor solution.

[0050] The pre-treatment substrate was subjected to two-stage spin coating with the precursor solution, the first stage spin coating speed was 1000 rpm, the time was 9 s, the second stage spin coating speed was 3000 rpm, the time was 21 s, while the second stage spin coating was added 0.19 mL of ethyl acetate at the 12th s, after adding ethyl acetate for 5 s, the substrate was subjected to light treatment under the ultraviolet light with the wavelength of 365-405 nm and the light intensity of 15 mW·cm -2The substrate was subjected to ultraviolet light irradiation treatment for 15 s, and immediately after the irradiation treatment, the substrate was subjected to micro-vibration with a parameter of 40 kHz and an equivalent acceleration of 0.2 G for 20 s, and then the substrate was placed on a hot plate and heated to 110 DEG C for 25 min to obtain a perovskite film.

[0051] Example 6 The substrate was subjected to ultrasonic cleaning, nitrogen blowing and drying, and UV-O3 treatment for 15 min, and then SnO2 glue was spin-coated at a speed of 2800 rpm for 35 s, and then the substrate was dried at 150 DEG C for 30 min to obtain a pretreated substrate.

[0052] A dry three-necked flask was taken, 2.5 mL of anhydrous acetonitrile was added, 0.1 g of octakis(aminophenyltrisiloxane) was added under the condition of 0-5 DEG C ice bath, and then 0.1 mL of 60wt% HI aqueous solution was slowly added dropwise, and stirred at room temperature for 30 min, and then precipitated in anhydrous ether, and then filtered, washed and dried at 40 DEG C under vacuum for 12 h to obtain modified octakis(aminophenyltrisiloxane).

[0053] In the glove box, 0.66 g of dimethyl sulfoxide and 2.97 g of N,N-dimethylformamide were added to a beaker, and then 865.3 mg of formamidinium hydriodide, 2563.2 mg of lead iodide, 108 mg of chlorosulfonyl isocyanate, 18 mg of methylammonium bromide, 70 mg of methylammonium chloride and 15 mg of urea were sequentially added, heated to 50 DEG C and stirred for 15 min, and then 7 mg of modified octakis(aminophenyltrisiloxane) was added and stirred until completely dissolved, and then 12 mg of triphenylsulfonium p-toluenesulfonate was added, and after mixing, filtered using a 0.45 µm PTFE, and then left to stand for 40 min to obtain a precursor solution.

[0054] The pretreated substrate was subjected to two-stage spin coating using the precursor solution, the first-stage spin coating was performed at a speed of 1000 rpm for 11 s, and the second-stage spin coating was performed at a speed of 3000 rpm for 19 s, and at the same time, 0.22 mL of ethyl acetate was added dropwise at the 12th s of the second-stage spin coating, and 5 s after the addition of the ethyl acetate, ultraviolet light irradiation treatment was performed for 15 s under the condition of a wavelength of 365-405 nm and a light intensity of 15 mW·cm -2 The substrate was subjected to ultraviolet light irradiation treatment for 15 s, and immediately after the irradiation treatment, the substrate was subjected to micro-vibration with a parameter of 40 kHz and an equivalent acceleration of 0.2 G for 20 s, and then the substrate was placed on a hot plate and heated to 110 DEG C for 25 min to obtain a perovskite film.

[0055] Example 7 The substrate was ultrasonically cleaned, dried with nitrogen, treated with UV-O3 for 15 min, spin-coated with SnO2 glue at a speed of 2800 rpm for 35 s, dried at 150 DEG C for 30 min, and cooled to room temperature to obtain a pretreated substrate.

[0056] A dry three-necked flask was taken, 2.5 mL of anhydrous acetonitrile was added, 0.1 g of octakis(aminophenyltrisiloxane) was added under the condition of 0-5 DEG C ice bath, then 0.1 mL of 60 wt% HI aqueous solution was slowly added dropwise, stirred at room temperature for 30 min, precipitated in anhydrous ether, suction filtered, washed, and dried at 40 DEG C under vacuum for 12 h to obtain modified octakis(aminophenyltrisiloxane).

[0057] In the glove box, 0.66 g of dimethyl sulfoxide and 2.97 g of N,N-dimethylformamide were added to a beaker, then 865.3 mg of formamidinium iodide, 2563.2 mg of lead iodide, 108 mg of chlorosulfonyl isocyanate, 18 mg of methylammonium bromide, 70 mg of methylammonium chloride, and 15 mg of urea were sequentially added, heated to 50 DEG C, stirred for 15 min, then 7 mg of modified octakis(aminophenyltrisiloxane) was added, stirred until completely dissolved, filtered using a 0.45 µm PTFE, and stood for 40 min to obtain a precursor solution.

[0058] The pretreated substrate was spin-coated with the precursor solution in two stages, the first stage was spin-coated at a speed of 1000 rpm for 11 s, the second stage was spin-coated at a speed of 3000 rpm for 19 s, while 0.22 mL of ethyl acetate was added dropwise at the 12th s of the second stage, 5 s after the addition of ethyl acetate, the substrate was irradiated with ultraviolet light at a wavelength of 365-405 nm and an intensity of 15 mW·cm-2 for 15 s, after the irradiation was completed, the substrate was subjected to micro-vibration immediately, the parameters were 35 kHz, the equivalent acceleration was 0.2G, and the time was 20 s, then the substrate was placed on a hot plate and heated to 110 DEG C for 25 min to obtain a perovskite film. -2

[0059] The present application also carries out comparative examples and related tests.

[0060] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, modified octakis(aminophenyltrisiloxane) is not prepared, but octakis(aminophenyltrisiloxane) is directly used, and the other components and preparation methods are the same as those of Example 1, to obtain a perovskite film.

[0061] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, the precursor is not spin-coated, and the other components and preparation methods are the same as those of Example 1, to obtain a perovskite film.​

[0062] Performance test The perovskite thin films prepared from Examples 1-7 and Comparative Examples 1-2 were respectively used for solar cells, and performance tests were carried out, using a AAA-grade solar simulator with a light intensity of 100 mW·cm -2 The test results were open-circuit voltage, fill factor, short-circuit current density, photoelectric conversion efficiency and photoelectric conversion efficiency stability, wherein the photoelectric conversion efficiency = open-circuit voltage x short-circuit current density x fill factor; the test results are shown in Table 1.

[0063] Table 1

[0064] As can be seen from the above Table 1, the open-circuit voltage, fill factor and short-circuit current density of the perovskite thin film prepared from Comparative Example 1 for the solar cell have a more obvious decrease compared with Example 1, resulting in a decrease in the photoelectric conversion efficiency of the solar cell prepared therefrom, and its long-term stability is also obviously insufficient, indicating that the modified octakis(aminophenyltrioxysilane) can stabilize the crystallization of the precursor solution, obtain a more dense and uniform perovskite thin film, and further improve the photoelectric conversion efficiency of the solar cell; compared with Example 1, the open-circuit voltage, fill factor, short-circuit current density and photoelectric conversion efficiency stability of the perovskite thin film prepared from Comparative Example 2 have a slight degree of decrease, indicating that the use of a micro-vibration process helps to further reduce the surface roughness of the perovskite thin film, thereby reducing the series resistance of the solar cell and improving the fill factor.

[0065] The difference between Example 7 and Example 6 is that triphenylsulfonium p-toluenesulfonate is not used, resulting in a greater difference in the open-circuit voltage, fill factor and short-circuit current density of the perovskite thin film prepared therefrom for the solar cell compared with Example 6, indicating that triphenylsulfonium p-toluenesulfonate can promote defect passivation, thereby improving the photoelectric conversion efficiency of the solar cell.

[0066] Figure 1 、 Figure 2 、 Figure 3 The scanning electron microscope images of the perovskite thin films prepared from Example 1, Example 3 and Example 5, respectively, can be seen from the figures that the obtained perovskite thin films have a high degree of compactness, few pinhole defects and a relatively uniform thickness, and in combination with the data in Table 1, it can be shown that the perovskite thin films prepared in the examples are helpful to improve the performance of the solar cell.

[0067] The above is the preferred embodiment of the present application, and those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the protection scope of the present application.

Claims

1. A method for preparing a perovskite thin film, characterized in that, Includes the following steps: Step S1: Under ice bath conditions, octa(aminophenyltrioxosilane) was added to anhydrous acetonitrile, and then HI aqueous solution was slowly added dropwise. After stirring evenly, the mixture was poured into anhydrous diethyl ether to precipitate, filtered, washed, and dried to obtain modified octa(aminophenyltrioxosilane). Step S2: In a glove box, add dimethyl sulfoxide and N,N-dimethylformamide to a beaker, then add formamidinium hydroiodate, lead iodide, chlorosulfonyl isocyanate, methyl ammonium bromide, methyl ammonium chloride and urea in sequence, heat and stir, then add modified octa(aminophenyl trioxane), stir until completely dissolved, filter with polytetrafluoroethylene, let stand, and obtain the precursor solution; Step S3: Spin-coating the pretreated substrate with a precursor solution while adding ethyl acetate dropwise, then irradiating it with ultraviolet light, followed immediately by micro-vibration and curing annealing to obtain a perovskite film.

2. The method for preparing a perovskite thin film according to claim 1, characterized in that, In step S1, the temperature of the ice bath is 0-5℃; the concentration of the HI aqueous solution is 55-60wt%.

3. The method for preparing a perovskite thin film according to claim 1, characterized in that, In step S2, the mass ratio of dimethyl sulfoxide to N,N-dimethylformamide is 1:(3.5-4.5).

4. The method for preparing a perovskite thin film according to claim 1, characterized in that, In step S2, the heating and stirring temperature is 40-60℃, and the time is 10-20 minutes.

5. The method for preparing a perovskite thin film according to claim 1, characterized in that, In step S2, modified octa(aminophenyltrioxosilane) is added and stirred until completely dissolved. Triphenylthionium p-toluenesulfonate is then added and mixed thoroughly.

6. The method for preparing a perovskite thin film according to claim 1, characterized in that, In step S3, the preparation of the pretreated substrate includes the following steps: ultrasonic cleaning of the substrate, nitrogen blowing, UV-O3 treatment, spin coating with SnO2 adhesive, drying, and cooling to room temperature to obtain the pretreated substrate.

7. The method for preparing a perovskite thin film according to claim 6, characterized in that, The spin coating speed is 2700-3200 rpm, and the time is 25-40 s.

8. The method for preparing a perovskite thin film according to claim 1, characterized in that, In step S3, spin coating includes a first spin coating stage and a second spin coating stage. The spin coating time for the first stage is 8-12 seconds, and the spin coating time for the second stage is 18-22 seconds.

9. The method for preparing a perovskite thin film according to claim 1, characterized in that, In step S3, the wavelength of the ultraviolet light is 365-405nm; the frequency of the micro-vibration is 35-45kHz.

10. A perovskite thin film, characterized in that, The perovskite thin film was prepared using the method described in any one of claims 1-9, wherein the precursor solution comprises the following raw materials in parts by weight: 6.6 parts of dimethyl sulfoxide, 23.1-29.7 parts of N,N-dimethylformamide, 8.653 parts of formamidinium hydroiodate, 25.632 parts of lead iodide, 1.08 parts of chlorosulfonyl isocyanate, 0.18 parts of methyl ammonium bromide, 0.7 parts of methyl ammonium chloride, 0.15 parts of urea, and 0.07 parts of modified octa(aminophenyl trioxosilane).

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