A perovskite thin film and its preparation method

Abstract

This invention provides a perovskite thin film and its preparation method, belonging to the field of perovskite thin film technology. The method includes the following steps: Step S1, preparing modified octa-(aminophenyltrioxosilane); Step S2, preparing a precursor solution; Step S3, spin-coating a pretreated substrate with the precursor solution while simultaneously adding ethyl acetate, followed by ultraviolet light irradiation, and then immediately subjecting the substrate to micro-vibration, curing, and annealing to obtain the perovskite thin film. The perovskite thin film obtained by this invention can achieve the goals of simultaneously improving the open-circuit voltage and fill factor of solar cells, increasing photoelectric conversion efficiency, and enhancing long-term stability.

Description

Technical Field

[0001] This invention relates to the field of perovskite thin film technology, and specifically to a perovskite thin film and its preparation method. Background Technology

[0002] Perovskite solar cells (PSCs) have become a research hotspot in next-generation photovoltaic technology due to their excellent photoelectric conversion efficiency, low raw material cost, and convenient solution-based fabrication process. The quality of their photoactive layer—the perovskite thin film—especially its crystallinity, coverage, and defect state density, directly determines the final performance and stability of the cell. Ideal high-efficiency cells require perovskite thin films with large grains, high purity, low pinhole density, and good interfacial contact to promote efficient separation and extraction of photogenerated carriers and suppress non-radiative recombination. However, films prepared by the traditional one-step spin-coating method often exhibit excessively rapid and difficult-to-control crystallization processes, easily forming porous and non-uniform morphologies accompanied by numerous grain boundaries and bulk defects. These problems severely restrict further improvements in cell efficiency and affect their operational stability.

[0003] To optimize the quality of perovskite thin films, existing technologies generally employ the method of adding additives to the precursor solution. Commonly used additives, such as metal cations and organic molecules, can improve the film quality to some extent, but they often have limitations in simultaneously achieving crystallization guidance, defect passivation, and long-term stability improvement.

[0004] Patent document CN116406208A discloses a perovskite thin film, its preparation method, and a perovskite thin film optoelectronic device. This method involves immersing a lead iodide thin film in a heated anisole solution or isopropanol solution for a first annealing to obtain a mesoporous lead iodide thin film. An organic cation solution is then coated onto the mesoporous lead iodide thin film for a second annealing to obtain the perovskite thin film. While this method improves the crystallinity of the perovskite thin film, it still has shortcomings in defect passivation, and the photoelectric conversion efficiency of the battery prepared from this thin film is not high.

[0005] Therefore, there is a need to provide a perovskite thin film and a method for preparing the same, in order to solve the problems existing in the prior art. Summary of the Invention

[0006] In view of this, the present invention provides a perovskite thin film and its preparation method, which can achieve the goals of simultaneously improving the open-circuit voltage and fill factor of solar cells, improving photoelectric conversion efficiency, and enhancing long-term stability.

[0007] To achieve the above objectives, the present invention provides a method for preparing perovskite thin films, comprising the following steps:

[0008] 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).

[0009] 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;

[0010] 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.

[0011] Octa(aminophenyltrioxosilane) is neutral and tends to aggregate and has poor compatibility in strong ionic precursor systems. Direct addition to the precursor system easily leads to the formation of micron-sized particles or localized enrichment. Furthermore, the -NH2 group in octa(aminophenyltrioxosilane) is a Lewis base, readily reacting with Pb in the precursor solution. 2+ The formation of strong complexes disrupts crystallization kinetics and affects crystallization; simultaneously, it can induce deprotonation of FA / MA, leading to uncontrollable intermediate phases and residues; furthermore, the electrically neutral -NH2 is mainly adsorbed on crystal faces or SnO2 interfaces through weak hydrogen bonding, and cannot permanently and firmly "occupy" defects; the octa(aminophenyltrioxosilane) bulk lacks halide anions, making it difficult to specifically compensate for I... - This is a dominant trap, like the one involving gaps in the portfolio.

[0012] By modifying octa(aminophenyltrioxosilane) with HI, the overall polarity increases after protonation. The modified octa(aminophenyltrioxosilane) possesses a positively charged NH group. 3+ I - It can be stably dispersed in a dimethyl sulfoxide / N,N-dimethylformamide / salt environment, with greatly improved compatibility, which can significantly reduce the risk of aggregation, and -NH 3+ It no longer acts as a strong Lewis base, thus avoiding interaction with Pb. 2+ Excessive complexation and side reactions make crystallization more controllable and prevent the formation of other intermediate phases. Modification also introduces I-phase homologous to the crystal lattice. - It can directly compensate for I - Empty space, realize I - Targeted compensation for vacancy; -NH 3+Stablely fixed at grain boundary / surface defect sites by electrostatics and hydrogen bonding, its passivation strength is far higher than that of neutral amines. An octa(aminophenyltrioxosilane) molecule has eight -NH groups. 3+ I - Anchor points can bridge adjacent grain boundaries, reducing grain boundary barriers and ion migration. Positively charged surfaces can cooperate with SnO2's -OH groups and surface defects to form a stable hydrogen bond network, improving the wettability and adhesion of the precursor solution. Modified octa(aminophenyltrioxosilane) results in a denser and more uniform perovskite film with reduced pinholes and edge thickness; it also helps stabilize the precursor solution after solvent resistance and crystallization, thereby achieving short-circuit current stability.

[0013] Formamidinium hydroiodate and lead iodide can form a perovskite matrix with strong near-infrared absorption and good energy level matching in the precursor solution, thereby ensuring carrier generation rate and laying the foundation for improving short-circuit current. Methylammonium chloride can act as a crystallization regulator, Cl... - The introduction of [a specific ingredient] can lower the nucleation barrier, guide vertical growth, and obtain films with larger grains and fewer grain boundaries. Furthermore, methylammonium chloride volatilizes during the later stages of annealing and does not remain in the final film, thus avoiding band gap changes. [The text then abruptly shifts to a seemingly unrelated topic:] Methylammonium bromide contains a portion of MA [a specific ingredient]. + and Br - They can enter the perovskite lattice to form mixed cation perovskite or halide 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, thereby improving the open circuit voltage and fill factor of the solar cell and improving the photoelectric conversion efficiency.

[0014] This invention employs a micro-vibration process after spin-coating the precursor solution to promote solvent-antisolvent exchange and the outward diffusion of small molecules, thereby helping to homogenize crystal nuclei and fill micropores. This further reduces the surface roughness of the perovskite film, improves the interfacial contact effect, and thus achieves a decrease in series resistance and an increase in the fill factor. Furthermore, it avoids the later phase transition caused by solvent retention, thereby improving the long-term stability of the film.

[0015] Preferably, in step S1, the temperature of the ice bath is 0-5°C; and the concentration of the HI aqueous solution is 55-60 wt%.

[0016] Preferably, in step S2, the mass ratio of dimethyl sulfoxide to N,N-dimethylformamide is 1:(3.5-4.5).

[0017] Dimethyl sulfoxide, as a strong coordinating solvent, forms a complex with lead iodide, delaying instantaneous nucleation and widening the spin coating process window; N,N-dimethylformamide regulates viscosity and evaporation rate, providing a controllable action time for solvent-induced anti-solvent treatment.

[0018] Preferably, in step S2, the heating and stirring temperature is 40-60℃ and the time is 10-20 minutes.

[0019] Preferably, after adding modified octa(aminophenyltrioxosilane) and stirring until completely dissolved, triphenylthionium p-toluenesulfonate is also added and mixed thoroughly.

[0020] Upon exposure to light, triphenylthionium p-toluenesulfonate can release a strong acid in situ, accelerating the decomposition and crystallization of the mesophase. This reduces the required annealing temperature and time. Furthermore, its low acid content and short reaction time prevent halogen migration and corrosion. In addition, the acidic environment created by triphenylthionium p-toluenesulfonate can convert unreacted amines into -NH4+. 3+ This state further promotes defect passivation.

[0021] Preferably, in step S4, 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.

[0022] Ultrasonic cleaning, nitrogen drying, and UV ozone treatment of the substrate significantly remove organic contaminants and introduce hydroxyl groups onto the substrate surface, enhancing its surface energy and wettability. This results in a denser, pinhole-free tin dioxide colloid spin coating. After spin coating and drying, the tin dioxide's conduction band position matches that of lead iodide-based perovskites, enabling selective contact that is electron-friendly and hole-blocking.

[0023] Preferably, the spin coating speed is 2700-3200 rpm and the time is 25-40 s.

[0024] Preferably, in step S3, the spin coating includes a first spin coating stage and a second spin coating stage, with the first spin coating stage taking 8-12 seconds and the second spin coating stage taking 18-22 seconds.

[0025] The first stage of low-speed spin coating achieves the spreading and leveling of the precursor solution. The second stage of high-speed spin coating and dropwise addition of ethyl acetate can rapidly reduce the solubility and dielectric constant, achieve uniform supersaturation on the substrate, form a dense solvated mesophase and lock the morphology, which helps to reduce pinholes and edge buildup in the film.

[0026] Preferably, in step S3, the wavelength of the ultraviolet light is 365-405nm; and the frequency of the micro-vibration is 35-45kHz.

[0027] To achieve the above objectives, the present invention also provides a perovskite thin film prepared by the above-described method for preparing a perovskite thin film, wherein the precursor solution comprises the following raw materials in parts by weight:

[0028] 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).

[0029] The perovskite thin film prepared by the method of this invention can achieve the goal of simultaneously improving the open-circuit voltage and fill factor of solar cells, increasing photoelectric conversion efficiency, and enhancing long-term stability.

[0030] The above-described technical solution of the present invention has at least the following beneficial effects:

[0031] 1. By modifying octa(aminophenyltrioxane) with HI, the compatibility and dispersibility of octa(aminophenyltrioxane) are effectively improved, and defect passivation is achieved. This results in a denser and more uniform perovskite film with reduced pinholes and thicker edges. It also helps the precursor solution to crystallize more stably after solvent resistance, thereby stabilizing the short-circuit current of the solar cell.

[0032] 2. Methylammonium chloride and methylammonium bromide can promote perovskite films to have lower surface and grain boundary traps, thereby reducing recombination current and improving the open-circuit voltage and fill factor of solar cells. At the same time, uniform crystallization is beneficial to the stability of short-circuit current of solar cells.

[0033] 3. The micro-vibration process homogenizes the crystal nuclei and fills the micropores, which helps to further reduce the surface roughness of the perovskite film, thereby reducing the series resistance of the solar cell and increasing the fill factor; it can also avoid the late-stage phase transition caused by solvent retention, thus improving the long-term stability of the film. Attached Figure Description

[0034] Figure 1 This is a scanning electron microscope image of the perovskite thin film prepared in Example 1 of the present invention;

[0035] Figure 2 This is a scanning electron microscope image of the perovskite thin film prepared in Example 3 of the present invention;

[0036] Figure 3 This is a scanning electron microscope image of the perovskite thin film prepared in Example 5 of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0038] Example 1

[0039] The substrate was ultrasonically cleaned, dried with nitrogen, treated with UV-O3 for 15 min, and then spin-coated with SnO2 adhesive at a speed of 3000 rpm for 35 s. After drying at 150℃ for 30 min, it was cooled to room temperature to obtain the pretreated substrate.

[0040] Take a dry three-necked flask, add 2.5 mL of anhydrous acetonitrile, add 0.1 g of octa(aminophenyltrioxosilane) under ice bath conditions of 0-5℃, and then slowly add 0.1 mL of 55 wt% HI aqueous solution. Stir at room temperature for 25 min, pour into anhydrous diethyl ether to precipitate, filter, wash, and vacuum dry at 40℃ for 12 h to obtain modified octa(aminophenyltrioxosilane).

[0041] In a glove box, 0.66 g of dimethyl sulfoxide and 2.97 g of N,N-dimethylformamide were added to a beaker, followed by 865.3 mg of formamidinium hydroiodate, 2563.2 mg of lead iodide, 108 mg of chlorosulfonyl isocyanate, 18 mg of methyl ammonium bromide, 70 mg of methyl ammonium chloride, and 15 mg of urea. The mixture was heated to 50 °C and stirred for 15 min. Then, 7 mg of modified octa(aminophenyltrioxosilane) was added and stirred until completely dissolved. 10 mg of triphenylthionium p-toluenesulfonate was added and mixed well. The mixture was then filtered through 0.45 µm PTFE and allowed to stand for 40 min to obtain the precursor solution.

[0042] The pretreated substrate was spin-coated in two stages using a precursor solution. The first stage spin-coating was performed at 1000 rpm for 10 s, and the second stage spin-coating was performed at 3000 rpm for 20 s. Simultaneously, 0.2 mL of ethyl acetate was added dropwise at the 12th s mark of the second stage spin-coating. Five s after the addition of ethyl acetate, a light source with a wavelength of 365-405 nm and an intensity of 15 mW·cm² was used. -2 The substrate was irradiated under ultraviolet light for 10 seconds. After the irradiation was completed, the substrate was immediately subjected to micro-vibration with parameters of 40 kHz, equivalent acceleration of 0.2 G, and time of 20 seconds. The substrate was then placed on a hot plate and heated to 110 °C for 25 minutes to anneal, thus obtaining a perovskite thin film.

[0043] Example 2

[0044] The substrate was ultrasonically cleaned, dried with nitrogen, treated with UV-O3 for 15 min, and then spin-coated with SnO2 adhesive at a speed of 2700 rpm for 40 s. After drying at 150℃ for 30 min, it was cooled to room temperature to obtain the pretreated substrate.

[0045] Take a dry three-necked flask, add 5 mL of anhydrous acetonitrile, add 0.2 g of octa(aminophenyltrioxosilane) under ice bath conditions of 0-5℃, and then slowly add 0.2 mL of 55 wt% HI aqueous solution. Stir at room temperature for 30 min, pour into anhydrous diethyl ether to precipitate, filter, wash, and vacuum dry at 40℃ for 12 h to obtain modified octa(aminophenyltrioxosilane).

[0046] In a glove box, 0.66 g of dimethyl sulfoxide and 2.97 g of N,N-dimethylformamide were added to a beaker, followed by 865.3 mg of formamidinium hydroiodate, 2563.2 mg of lead iodide, 108 mg of chlorosulfonyl isocyanate, 18 mg of methyl ammonium bromide, 70 mg of methyl ammonium chloride, and 15 mg of urea. The mixture was heated to 40 °C and stirred for 20 min. Then, 7 mg of modified octa(aminophenyltrioxosilane) was added and stirred until completely dissolved. 12 mg of triphenylthionium p-toluenesulfonate was added and mixed well. The mixture was then filtered through 0.45 µm PTFE and allowed to stand for 40 min to obtain the precursor solution.

[0047] The pretreated substrate was spin-coated in two stages using a precursor solution. The first stage spin-coating was performed at 1000 rpm for 12 s, and the second stage spin-coating was performed at 3000 rpm for 18 s. Simultaneously, 0.22 mL of ethyl acetate was added dropwise at the 12th s mark of the second stage spin-coating. Five s after the addition of ethyl acetate, a light source with a wavelength of 365-405 nm and an intensity of 15 mW·cm² was used. -2 The substrate was irradiated under ultraviolet light for 15 seconds. After the irradiation was completed, the substrate was immediately subjected to micro-vibration with parameters of 45 kHz, equivalent acceleration of 0.2 G, and time of 20 seconds. The substrate was then placed on a hot plate and heated to 110 °C for 25 minutes to anneal, thus obtaining a perovskite thin film.

[0048] Example 3

[0049] The substrate was ultrasonically cleaned, dried with nitrogen, treated with UV-O3 for 15 min, and then spin-coated with SnO2 adhesive at a speed of 3200 rpm for 25 s. It was then dried at 150℃ for 30 min and cooled to room temperature to obtain the pretreated substrate.

[0050] Take a dry three-necked flask, add 5 mL of anhydrous acetonitrile, add 0.2 g of octa(aminophenyltrioxosilane) under ice bath conditions of 0-5℃, and then slowly add 0.2 mL of 58 wt% HI aqueous solution. Stir at room temperature for 25 min, pour into anhydrous diethyl ether to precipitate, filter, wash, and vacuum dry at 40℃ for 12 h to obtain modified octa(aminophenyltrioxosilane).

[0051] 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 865.3 mg of formamidinium hydroiodate, 2563.2 mg of lead iodide, 108 mg of chlorosulfonyl isocyanate, 18 mg of methyl ammonium bromide, 70 mg of methyl ammonium chloride, and 15 mg of urea. The mixture was heated to 60 °C and stirred for 10 min. Then, 7 mg of modified octa(aminophenyltrioxosilane) was added and stirred until completely dissolved. 8 mg of triphenylthionium p-toluenesulfonate was added and mixed well. The mixture was then filtered through 0.45 µm PTFE and allowed to stand for 40 min to obtain the precursor solution.

[0052] The pretreated substrate was spin-coated in two stages using a precursor solution. The first stage spin-coating was performed at 1000 rpm for 8 seconds, and the second stage spin-coating was performed at 3000 rpm for 22 seconds. Simultaneously, 0.18 mL of ethyl acetate was added dropwise at the 12th second of the second stage spin-coating. Five seconds after the addition of ethyl acetate, a light source with a wavelength of 365-405 nm and an intensity of 15 mW·cm² was used. -2 The substrate was irradiated under ultraviolet light for 10 seconds. After the irradiation was completed, the substrate was immediately subjected to micro-vibration with parameters of 35 kHz, equivalent acceleration of 0.2 G, and time of 20 seconds. The substrate was then placed on a hot plate and heated to 110 °C for 25 minutes to anneal, thus obtaining a perovskite thin film.

[0053] Example 4

[0054] The substrate was ultrasonically cleaned, dried with nitrogen, treated with UV-O3 for 15 min, and then SnO2 adhesive was spin-coated at a speed of 2900 rpm for 35 s. After drying at 150℃ for 30 min, it was cooled to room temperature to obtain the pretreated substrate.

[0055] Take a dry three-necked flask, add 2.5 mL of anhydrous acetonitrile, add 0.1 g of octa(aminophenyltrioxosilane) under ice bath conditions of 0-5℃, and then slowly add 0.1 mL of 60 wt% HI aqueous solution. Stir at room temperature for 20 min, pour into anhydrous diethyl ether to precipitate, filter, wash, and vacuum dry at 40℃ for 12 h to obtain modified octa(aminophenyltrioxosilane).

[0056] 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 865.3 mg of formamidinium hydroiodate, 2563.2 mg of lead iodide, 108 mg of chlorosulfonyl isocyanate, 18 mg of methyl ammonium bromide, 70 mg of methyl ammonium chloride, and 15 mg of urea. The mixture was heated to 45 °C and stirred for 20 min. Then, 7 mg of modified octa(aminophenyltrioxosilane) was added and stirred until completely dissolved. 10 mg of triphenylthionium p-toluenesulfonate was added and mixed well. The mixture was then filtered through 0.45 µm PTFE and allowed to stand for 40 min to obtain the precursor solution.

[0057] The pretreated substrate was spin-coated in two stages using a precursor solution. The first stage spin-coating was performed at 1000 rpm for 10 s, and the second stage spin-coating was performed at 3000 rpm for 20 s. Simultaneously, 0.18 mL of ethyl acetate was added dropwise at the 12th s mark of the second stage spin-coating. Five s after the addition of ethyl acetate, a light source with a wavelength of 365-405 nm and an intensity of 15 mW·cm² was used. -2 The substrate was irradiated under ultraviolet light for 15 seconds. After the irradiation was completed, the substrate was immediately subjected to micro-vibration with parameters of 45 kHz, equivalent acceleration of 0.2 G, and time of 20 seconds. The substrate was then placed on a hot plate and heated to 110 °C for 25 minutes to anneal, thus obtaining a perovskite thin film.

[0058] Example 5

[0059] The substrate was ultrasonically cleaned, dried with nitrogen, treated with UV-O3 for 15 min, and then spin-coated with SnO2 adhesive at a speed of 3200 rpm for 30 s. After drying at 150℃ for 30 min, it was cooled to room temperature to obtain the pretreated substrate.

[0060] Take a dry three-necked flask, add 5 mL of anhydrous acetonitrile, add 0.2 g of octa(aminophenyltrioxosilane) under ice bath conditions of 0-5℃, and then slowly add 0.2 mL of 55 wt% HI aqueous solution. Stir at room temperature for 25 min, pour into anhydrous diethyl ether to precipitate, filter, wash, and vacuum dry at 40℃ for 12 h to obtain modified octa(aminophenyltrioxosilane).

[0061] In a glove box, 0.66 g of dimethyl sulfoxide and 2.97 g of N,N-dimethylformamide were added to a beaker, followed by 865.3 mg of formamidinium hydroiodate, 2563.2 mg of lead iodide, 108 mg of chlorosulfonyl isocyanate, 18 mg of methyl ammonium bromide, 70 mg of methyl ammonium chloride, and 15 mg of urea. The mixture was heated to 40 °C and stirred for 20 min. Then, 7 mg of modified octa(aminophenyltrioxosilane) was added and stirred until completely dissolved. 8 mg of triphenylthionium p-toluenesulfonate was added and mixed well. The mixture was then filtered through 0.45 µm PTFE and allowed to stand for 40 min to obtain the precursor solution.

[0062] The pretreated substrate was spin-coated in two stages using a precursor solution. The first stage spin-coating was performed at 1000 rpm for 9 s, and the second stage spin-coating was performed at 3000 rpm for 21 s. Simultaneously, 0.19 mL of ethyl acetate was added dropwise at the 12th s mark of the second stage spin-coating. Five s after the addition of ethyl acetate, a light source with a wavelength of 365-405 nm and an intensity of 15 mW·cm² was used. -2 The substrate was irradiated under ultraviolet light for 15 seconds. After the irradiation was completed, the substrate was immediately subjected to micro-vibration with parameters of 40 kHz, equivalent acceleration of 0.2 G, and time of 20 seconds. The substrate was then placed on a hot plate and heated to 110 °C for 25 minutes to anneal, thus obtaining a perovskite thin film.

[0063] Example 6

[0064] The substrate was ultrasonically cleaned, dried with nitrogen, treated with UV-O3 for 15 min, and then spin-coated with SnO2 adhesive at a speed of 2800 rpm for 35 s. After drying at 150℃ for 30 min, it was cooled to room temperature to obtain the pretreated substrate.

[0065] Take a dry three-necked flask, add 2.5 mL of anhydrous acetonitrile, add 0.1 g of octa(aminophenyltrioxosilane) under ice bath conditions of 0-5℃, and then slowly add 0.1 mL of 60 wt% HI aqueous solution. Stir at room temperature for 30 min, pour into anhydrous diethyl ether to precipitate, filter, wash, and vacuum dry at 40℃ for 12 h to obtain modified octa(aminophenyltrioxosilane).

[0066] In a glove box, 0.66 g of dimethyl sulfoxide and 2.97 g of N,N-dimethylformamide were added to a beaker, followed by 865.3 mg of formamidinium hydroiodate, 2563.2 mg of lead iodide, 108 mg of chlorosulfonyl isocyanate, 18 mg of methyl ammonium bromide, 70 mg of methyl ammonium chloride, and 15 mg of urea. The mixture was heated to 50 °C and stirred for 15 min. Then, 7 mg of modified octa(aminophenyltrioxosilane) was added and stirred until completely dissolved. 12 mg of triphenylthionium p-toluenesulfonate was added and mixed well. The mixture was then filtered through 0.45 µm PTFE and allowed to stand for 40 min to obtain the precursor solution.

[0067] The pretreated substrate was spin-coated in two stages using a precursor solution. The first stage spin-coating was performed at 1000 rpm for 11 s, and the second stage spin-coating was performed at 3000 rpm for 19 s. Simultaneously, 0.22 mL of ethyl acetate was added dropwise at the 12th s mark of the second stage spin-coating. Five s after the addition of ethyl acetate, a light source with a wavelength of 365-405 nm and an intensity of 15 mW·cm² was used. -2 The substrate was irradiated under ultraviolet light for 15 seconds. After the irradiation was completed, the substrate was immediately subjected to micro-vibration with parameters of 35 kHz, equivalent acceleration of 0.2 G, and time of 20 seconds. The substrate was then placed on a hot plate and heated to 110 °C for 25 minutes to anneal, thus obtaining a perovskite thin film.

[0068] Example 7

[0069] The substrate was ultrasonically cleaned, dried with nitrogen, treated with UV-O3 for 15 min, and then spin-coated with SnO2 adhesive at a speed of 2800 rpm for 35 s. After drying at 150℃ for 30 min, it was cooled to room temperature to obtain the pretreated substrate.

[0070] Take a dry three-necked flask, add 2.5 mL of anhydrous acetonitrile, add 0.1 g of octa(aminophenyltrioxosilane) under ice bath conditions of 0-5℃, and then slowly add 0.1 mL of 60 wt% HI aqueous solution. Stir at room temperature for 30 min, pour into anhydrous diethyl ether to precipitate, filter, wash, and vacuum dry at 40℃ for 12 h to obtain modified octa(aminophenyltrioxosilane).

[0071] In a glove box, 0.66 g of dimethyl sulfoxide and 2.97 g of N,N-dimethylformamide were added to a beaker, followed by 865.3 mg of formamidinium hydroiodate, 2563.2 mg of lead iodide, 108 mg of chlorosulfonyl isocyanate, 18 mg of methyl ammonium bromide, 70 mg of methyl ammonium chloride, and 15 mg of urea. The mixture was heated to 50 °C and stirred for 15 min. Then, 7 mg of modified octa(aminophenyltrioxosilane) was added and stirred until completely dissolved. The mixture was filtered through 0.45 µm PTFE and allowed to stand for 40 min to obtain the precursor solution.

[0072] The pretreated substrate was spin-coated in two stages using a precursor solution. The first stage spin-coating was performed at 1000 rpm for 11 s, and the second stage spin-coating was performed at 3000 rpm for 19 s. Simultaneously, 0.22 mL of ethyl acetate was added dropwise at the 12th s mark of the second stage spin-coating. Five s after the addition of ethyl acetate, a light source with a wavelength of 365-405 nm and an intensity of 15 mW·cm² was used. -2 The substrate was irradiated under ultraviolet light for 15 seconds. After the irradiation was completed, the substrate was immediately subjected to micro-vibration with parameters of 35 kHz, equivalent acceleration of 0.2 G, and time of 20 seconds. The substrate was then placed on a hot plate and heated to 110 °C for 25 minutes to anneal, thus obtaining a perovskite thin film.

[0073] The present invention also includes comparative examples and related experiments.

[0074] Comparative Example 1

[0075] The difference between Comparative Example 1 and Example 1 is that, in Comparative Example 1, modified octa(aminophenyltrioxosilane) was not prepared, but octa(aminophenyltrioxosilane) was used directly. The other components and preparation methods were the same as in Example 1, and perovskite thin films were prepared.

[0076] Comparative Example 2

[0077] The difference between Comparative Example 2 and Example 1 is that, in Comparative Example 2, after spin coating of the precursor, no micro-vibration process was used. The other components and preparation methods were the same as in Example 1, and a perovskite thin film was prepared.

[0078] Performance testing

[0079] The perovskite thin films prepared in Examples 1-7 and Comparative Examples 1-2 were used in solar cells, and their performance was tested using an AAA-grade solar simulator with a light intensity of 100 mW·cm². -2 The test results were based on open-circuit voltage, fill factor, short-circuit current density, photoelectric conversion efficiency, and photoelectric conversion efficiency stability. The photoelectric conversion efficiency was calculated as open-circuit voltage × short-circuit current density × fill factor. The test results are shown in Table 1.

[0080] Table 1

[0081]

[0082] As can be seen from the results in Table 1 above, the perovskite thin film prepared in Comparative Example 1 shows a significant decrease in open-circuit voltage, fill factor, and short-circuit current density of the solar cell compared to Example 1, resulting in a decrease in the photoelectric conversion efficiency of the solar cell and a significant deficiency in its long-term stability. This indicates that the modified octa(aminophenyltrioxosilane) can stabilize the crystallization of the precursor solution, resulting in a more dense and uniform perovskite thin film, thereby improving the photoelectric conversion efficiency of the solar cell. Compared to Example 1, the perovskite thin film prepared in Comparative Example 2 shows a slight decrease in open-circuit voltage, fill factor, short-circuit current density, and photoelectric conversion efficiency stability of the solar cell. This indicates that the 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.

[0083] The difference between Example 7 and Example 6 is that Triphenylthionium p-toluenesulfonate was not used. As a result, the open-circuit voltage, fill factor and short-circuit current density of the perovskite thin film prepared in Example 7 are significantly different from those in Example 6. This indicates that Triphenylthionium p-toluenesulfonate can promote defect passivation and thus improve the photoelectric conversion efficiency of the solar cell.

[0084] Figure 1 , Figure 2 , Figure 3 The images show scanning electron microscope (SEM) images of the perovskite films prepared in Examples 1, 3, and 5, respectively. As can be seen from the images, the perovskite films prepared in these examples have high density, few pinhole defects, and relatively uniform thickness. Combined with the data in Table 1, it can be shown that the perovskite films prepared in these examples help to improve the performance of solar cells.

[0085] The above are preferred embodiments of the present invention. Those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

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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