Perovskite thin film, preparation method and application thereof

Abstract

The application discloses a preparation method of a perovskite thin film, which comprises the following steps: coating a perovskite precursor solution on a substrate to prepare a perovskite wet film, and performing gas quenching on the perovskite wet film; and performing ultrasonic oscillation treatment on the perovskite wet film after the gas quenching, and then performing annealing to obtain the perovskite thin film. The application further discloses the perovskite thin film prepared by the above preparation method and application of the perovskite thin film in a solar cell. The perovskite thin film is prepared through a gas quenching process, and then ultrasonic oscillation treatment is performed on the perovskite thin film to regulate and control a nucleation and crystallization process of the perovskite thin film, so that larger perovskite grains are obtained, grain boundary defects are reduced, and residual stress of the perovskite thin film is eliminated, thereby high-quality perovskite thin film is prepared. The method has the advantages of simple process, environmental protection in a preparation process and low cost. The solar cell prepared by using the perovskite thin film has high photoelectric conversion efficiency and stability, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, specifically relating to a perovskite thin film, its preparation method, and its application. Background Technology

[0002] Perovskite solar cells (PSCs), as a new generation of photovoltaic technology, have made tremendous progress. Their photoelectric conversion efficiency (PCE) has rapidly increased from 3.8% to 26.1% in just about ten years. The preparation of high-quality perovskite thin films is the key to obtaining high-performance PSCs.

[0003] Gas quenching is a simple, repeatable, and low-cost technique for preparing high-quality perovskite thin films, showing great potential for applications in high-efficiency, large-area perovskite films (PSCs). Compared to traditional antisolvent methods for perovskite preparation, gas quenching is considered more promising for large-scale PSC production in practical applications. Gas quenching not only avoids the use of harmful antisolvents but also exhibits high reproducibility and stability in preparing high-quality perovskites. However, PSCs prepared by gas quenching suffer from drawbacks such as small grain size and numerous defects at grain boundaries. Therefore, there is still significant room for improvement in PCE (Potentially Calcium Equivalent) performance of PSCs prepared by gas quenching.

[0004] The application of ultrasound during crystallization has been shown to significantly influence crystallization, affecting nucleation, crystal growth, and fragmentation. Ultrasound induces cavitation in solution, leading to enhanced micromixing, increased mass transfer rate, and uniform supersaturation, thereby reducing induction time and the width of the metastable region. Therefore, applying ultrasound to the perovskite film formation stage holds promise for controlling perovskite grain size, reducing grain boundaries, and thus improving the photoelectric conversion efficiency and stability of perovskite solar cells.

[0005] Patent document CN111180589B discloses a high-stability perovskite solar cell fabricated using an ultrasonic oscillation annealing process. The cell includes a perovskite photoactive layer, in which ultrasonic oscillation is incorporated during annealing at a stable temperature of 100°C and a fixed annealing time of 20 minutes, all within a nitrogen atmosphere. However, this method is only applicable to a single perovskite photoactive layer system (MAPbI3). Furthermore, the method involves directly performing ultrasonic oscillation annealing after spin-coating the perovskite active layer, with ultrasonic oscillation and heating occurring simultaneously. This results in significant uncontrollable factors in perovskite film formation, making it prone to defects.

[0006] Patent document CN114220924A discloses a method for preparing a perovskite thin film and a method for preparing a perovskite solar cell, comprising: coating a perovskite precursor solution onto a substrate to obtain a perovskite wet film; placing the perovskite wet film in an antisolvent containing additives and used to extract the solvent of the perovskite precursor solution, and then subjecting the antisolvent to ultrasonic treatment; and annealing the treated perovskite wet film to obtain a perovskite thin film. This invention has a complex process, high cost, and requires the use of toxic organic solvents during ultrasonic treatment.

[0007] Patent document CN113130759B discloses a method for rapidly removing surface defects of halide perovskite thin films and its application in perovskite solar cells. The method includes: depositing a halide perovskite precursor on a substrate, annealing and crystallizing it to obtain a perovskite thin film, immersing it in a washing solvent for ultrasonic cleaning, rinsing, and evaporating the solvent from the perovskite thin film surface to obtain a perovskite thin film with the defect-rich layer removed. This method is complex, and the ultrasonic cleaning of the perovskite thin film also requires the use of toxic organic solvents as the ultrasonic medium, making the preparation process environmentally unfriendly.

[0008] Therefore, in order to solve the above-mentioned technical problems, it is of great significance to find a simple, environmentally friendly and controllable method to prepare high-quality perovskite thin films, and then to prepare high-efficiency and stable perovskite solar cells. Summary of the Invention

[0009] In view of the shortcomings of the prior art, the present invention provides a method for preparing perovskite thin films. The method first prepares perovskite thin films by gas quenching, and then anneals the perovskite thin films prepared by gas quenching after ultrasonic vibration treatment. The preparation process is simple and environmentally friendly.

[0010] A method for preparing a perovskite thin film includes the following steps:

[0011] (1) A perovskite wet film is prepared by coating a perovskite precursor solution onto a substrate and then gas-quenching the perovskite wet film.

[0012] (2) After gas quenching, the perovskite wet film is subjected to ultrasonic vibration treatment and then annealed to obtain a perovskite thin film.

[0013] This invention first prepares a perovskite thin film using an air quenching process, and then treats the perovskite thin film prepared by the air quenching process with ultrasonic vibration to induce cavitation and enhanced micromixing, thereby controlling the nucleation and crystallization process of the perovskite thin film, obtaining larger perovskite grains, reducing grain boundary defects, and eliminating residual stress in the perovskite thin film, thus preparing a high-quality perovskite thin film.

[0014] Preferably, in step (1), the perovskite precursor is FA 1-x Cs x PbI 3-y Br y , where 0 < x < 1 and 0 < y < 3.

[0015] Preferably, in step (1), the perovskite precursor is FA 1-x-z MA z Cs x PbI 3-y Br y , where 0 < x < 1, 0 < y < 3, and 0 < z < 1.

[0016] Preferably, in step (1), the solvent of the perovskite precursor solution includes a DMF:DMSO mixed solvent with a volume ratio of 100:1 to 1:100, and a DMF:DMSO:NMP mixed solvent with a volume ratio of 1:x:y, where 0 < x < 100 and 0 < y < 100.

[0017] Preferably, in step (1), the coating includes spin coating, blade coating, microgravure coating, rod coating, screen printing coating, slot coating, ultrasonic spraying, or roll-to-roll processing.

[0018] Preferably, the spin coating is performed at 1000 - 12000 rpm for 5 - 600 s.

[0019] Preferably, the gas quenching is: after drying the perovskite wet film under a nitrogen gas flow, annealing it at 50 - 250 °C for 1 - 600 min.

[0020] More preferably, the gas quenching is: after drying the perovskite wet film under a nitrogen gas flow, annealing it at 50 - 250 °C for 1 - 360 min.

[0021] Preferably, gas quenching is performed on the perovskite wet film before the end of spin coating of the perovskite precursor solution.

[0022] Compared with the traditional anti-solvent method, gas quenching is considered to be a technology that is more likely to be used for preparing commercial large-area PSCs in practical applications. It not only avoids the use of additional toxic organic solvents, but also has good repeatability and reliability in preparing high-quality perovskite films, is environmentally friendly and has low costs, and is also applicable to scalable deposition methods such as blade coating and slot coating.

[0023] This invention involves gas quenching the perovskite wet film before spin-coating the perovskite precursor solution. This process accelerates the evaporation of the existing solvent in a short time, increases the supersaturation of the perovskite precursor, and thus promotes the formation of perovskite nuclei. This resolves the mismatch between the nucleation rate and growth rate present in the spontaneous growth of perovskite. After gas quenching, the film morphology changes from rough and porous to smooth and dense, resulting in a high-quality perovskite film.

[0024] More preferably, the perovskite wet film is gas quenched for at least 0–300 s before the spin coating of the perovskite precursor solution is completed.

[0025] Preferably, the ultrasonic oscillation power is 0.1 to 100 W, and the duration is 10 s to 60 min.

[0026] This invention allows for the direct ultrasonic vibration treatment of perovskite wet films after gas quenching, eliminating the need for any organic solvents as the ultrasonic medium. This avoids the use of toxic organic solvents, simplifies the operation process, and reduces production costs.

[0027] Preferably, in step (2), the annealing temperature is 50 to 250°C and the time is 1 to 600 min.

[0028] More preferably, the annealing temperature is 50–250°C and the time is 1–360 min.

[0029] The present invention also provides a perovskite thin film prepared by the above method. The perovskite thin film has larger perovskite grains and fewer grain boundary defects, and can be used in the fabrication of perovskite solar cells.

[0030] The present invention also provides a perovskite solar cell, comprising a perovskite light-absorbing layer, wherein the perovskite light-absorbing layer is the aforementioned perovskite thin film. The perovskite solar cell of the present invention uses the aforementioned perovskite thin film as the perovskite light-absorbing layer, exhibiting high photoelectric conversion efficiency and stability.

[0031] Preferably, the perovskite solar cell has an inverted structure, comprising, from bottom to top, a conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and a metal electrode.

[0032] Preferably, the hole transport layer is a MeO-2PACz, PTAA, 4PADCB, Me-4PACZ, or DMAcPA film with a thickness of 5-50 nm.

[0033] Preferably, the perovskite light-absorbing layer is FA. 1-x Cs x PbI 3-y Br yA thin film, where 0 < x < 1, 0 < y < 3, or FA 1-x-z MA z Cs x PbI 3-y Br y A thin film, where 0 < x < 1, 0 < y < 3, 0 < z < 1, and the thickness of the perovskite light absorption layer is 100 - 5000 nm.

[0034] More preferably, the perovskite light absorption layer is FA(4) 0.87 Cs 0.13 PbI 2.7 Br 0.3 or FA 0.96 Cs 0.04 PbI 2.8 Br 0.12 A thin film, and the thickness of the perovskite light absorption layer is 300 - 1000 nm.

[0035] Preferably, the electron transport layer is a PC61BM or C60 thin film with a thickness of 20 - 200 nm.

[0036] Preferably, the metal electrode is Ag with a thickness of 50 - 100 nm.

[0037] Preferably, the perovskite solar cell further includes a passivation layer, and the passivation layer is located between the electron transport layer and the electrode.

[0038] Preferably, the passivation layer is a BCP thin film with a thickness of 5 - 20 nm.

[0039] Compared with the prior art, the present invention has at least the following beneficial effects:

[0040] (1) The present invention first prepares a perovskite thin film through a gas quenching process, and then subjects the perovskite thin film prepared by the gas quenching process to ultrasonic oscillation treatment to cause cavitation effects and enhanced micro - mixing, so as to regulate the nucleation and crystallization process of the perovskite thin film, obtain larger perovskite grains, reduce grain boundary defects, and eliminate the residual stress of the perovskite thin film, thereby preparing a high - quality perovskite thin film.

[0041] (2) The process of the present invention is simple, and no toxic organic solvents are required as ultrasonic media during the preparation process. The preparation process is environmentally friendly and has a low cost.

[0042] (3) The method of the present invention is applicable to perovskites with different components and has universality.

[0043] (4) The solar cell prepared with the perovskite thin film of the present invention has high photoelectric conversion efficiency and stability, and its photoelectric conversion efficiency is as high as 22%. The description of the drawings

[0044] Figure 1 A scanning electron microscope image of the surface of the perovskite thin film prepared in Example 1 after ultrasonic vibration treatment;

[0045] Figure 2 Scanning electron microscope image of the surface of the perovskite thin film prepared in Comparative Example 1 without ultrasonic vibration treatment;

[0046] Figure 3 XRD patterns of perovskite films prepared by ultrasonic vibration treatment in Example 1 and perovskite films prepared by unultrasonic vibration treatment in Comparative Example 1.

[0047] Figure 4 Photoluminescence spectra of the perovskite thin films prepared in Example 1 after ultrasonic vibration treatment and those prepared in Comparative Example 1 without ultrasonic vibration treatment;

[0048] Figure 5 The current-voltage curves are shown for the perovskite solar cells prepared by ultrasonic oscillation treatment in Example 1 and those prepared by untreated perovskite solar cells in Comparative Example 1.

[0049] Figure 6 GIXRD patterns of the perovskite thin film prepared in Example 1 after ultrasonic vibration treatment at different Ψ angles with an incident angle of 0.5°;

[0050] Figure 7 GIXRD patterns of the perovskite thin film prepared for Comparative Example 1 without ultrasonic vibration treatment at different Ψ angles with an incident angle of 0.5°;

[0051] Figure 8 The perovskite films prepared by ultrasonic vibration treatment in Example 1 and those prepared by untreated perovskite films in Comparative Example 1. Linear fitting of curves;

[0052] Figure 9 Box plots showing the photoelectric conversion efficiency of perovskite solar cells prepared in Example 1 with different ultrasonic power treatments and those prepared in Comparative Example 1 without ultrasonic oscillation treatment.

[0053] Figure 10 The graph shows the voltage versus light intensity of the perovskite solar cells prepared by ultrasonic oscillation treatment in Example 1 and the perovskite solar cells prepared by untreated perovskite oscillation treatment in Comparative Example 1.

[0054] Figure 11 The image shows the light stability of the perovskite solar cell devices prepared in Example 1 (under ultrasonic vibration treatment) and Comparative Example 1 (under no ultrasonic vibration treatment) at the maximum power point. Detailed Implementation

[0055] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0056] Example 1: The PSCs in this example, from bottom to top, include an ITO conductive substrate layer, a MeO-2PACz hole transport layer, a FACs-based perovskite light absorption layer, and a PC. 61 BM electron transport layer, BCP passivation layer and Ag metal electrode.

[0057] The preparation method of PSCs in this embodiment is as follows:

[0058] (1) Select an ITO conductive glass with a sheet resistance of 15Ω, a transmittance of 85%, and a size of 1.9cm×1.9cm as the substrate. Before use, the ITO conductive substrate is first treated with deionized water, acetone and isopropanol in sequence by ultrasonic vibration, then dried with nitrogen, and then cleaned by ultraviolet light for 30 minutes.

[0059] (2) Preparation of MeO-2PACz hole transport layer: 0.6 mg MeO-2PACz was dissolved in 2 mL of ethanol to prepare MeO-2PACz ethanol solution. Then, 50 μL of MeO-2PACz ethanol solution was dropped onto the ITO conductive glass substrate prepared in step (1). The substrate was spin-coated at 3000 rpm for 30 s to deposit an ultrathin MeO-2PACz film on the ITO conductive glass substrate. Then, the substrate was annealed at 100 °C for 10 min.

[0060] (3) Preparation of perovskite light absorption layer in FACs system: 301 mg FAI, 53.2 mg CsBr, 806.8 mg PbI2 and 91.8 mg PbBr2 were dissolved in a mixed solvent of 1050 μL DMF and 150 μL DMSO to prepare perovskite precursor solution. The perovskite precursor solution was dropped onto the MeO-2PACz hole transport layer prepared in step (2). The perovskite wet film was prepared by spin coating at 4000 rpm for 25 s. The perovskite wet film was dried with nitrogen gas flow 10 s before the end of spin coating. Then it was annealed at 100℃ for 60 min. Then it was transferred to an ultrasonic stage and ultrasonically oscillated at 2W, 3W, 6W and 10W respectively for 3 min. Finally, it was annealed at 100℃ for 60 min.

[0061] (4)PC 61 Fabrication of the BM electron transport layer: PC 61 BM was dissolved in CB solvent to prepare PC with a concentration of 20 mg / ml. 61 BM-CB solution, i.e., PC 61 BM electron transport layer precursor solution, PC61 The BM electron transport layer precursor solution was spin-coated onto the perovskite light absorption layer prepared in step (3) at a speed of 2000 rpm for 30 s, and then annealed at 70 °C for 60 s to obtain a hole transport layer with a thickness of 100 nm.

[0062] (5) Preparation of BCP passivation layer: Dissolve BCP in IPA solvent to prepare 0.5 mg / ml BCP-IPA solution, i.e. BCP passivation layer precursor solution. Spin-coat the BCP passivation layer precursor solution onto the PC prepared in step (4). 61 On the BM electron transport layer, spin coating was performed at 4000 rpm for 30 s, followed by annealing at 100 °C for 60 s to obtain a passivation layer with a thickness of 10 nm.

[0063] (6) Preparation of Ag metal electrode: Place the sample prepared in step (5) into a vacuum evaporation coating equipment, and wait until the vacuum degree reaches 5×10 -4 After Pa, with and An Ag electrode coating with a thickness of 100 nm was deposited using an evaporation rate, resulting in a perovskite solar cell with an effective area of ​​0.04 cm². 2 .

[0064] Comparative Example 1: The PSCs in this comparative example, from bottom to top, include an ITO conductive substrate, a MeO-2PACz hole transport layer, a FACs-based perovskite light absorption layer, and a PC. 61 BM electron transport layer, BCP passivation layer and Ag metal electrode.

[0065] The preparation method of PSCs in this comparative example is as follows:

[0066] (1) Select an ITO conductive glass with a sheet resistance of 15Ω, a transmittance of 85%, and a size of 1.9cm×1.9cm as the substrate. Before use, the ITO conductive substrate is first treated with deionized water, acetone and isopropanol in sequence by ultrasonic vibration, then dried with nitrogen, and then cleaned by ultraviolet light for 30 minutes.

[0067] (2) Preparation of MeO-2PACz hole transport layer: 0.6 mg MeO-2PACz was dissolved in 2 mL of ethanol to prepare MeO-2PACz ethanol solution. Then, 50 μL of MeO-2PACz ethanol solution was dropped onto the ITO conductive glass substrate prepared in step (1). The substrate was spin-coated at 3000 rpm for 30 s to deposit an ultrathin MeO-2PACz film on the ITO conductive glass substrate. Then, the substrate was annealed at 100 °C for 10 min.

[0068] (3) Preparation of perovskite light absorption layer: The perovskite light absorption layer in this comparative example is a perovskite light absorption layer of FACs system. 301 mg FAI, 53.2 mg CsBr, 806.8 mg PbI2 and 91.8 mg PbBr2 were dissolved in 1050 μL DMF and 150 μL LDMSO solution to prepare perovskite precursor solution. The perovskite precursor solution was dropped onto the MeO-2PACz hole transport layer prepared in step (2), and a one-step spin coating program of 4000 rpm was used for 25 s to prepare a perovskite wet film. The perovskite wet film was dried with nitrogen gas flow 10 s before the end of spin coating, and then annealed at 100 °C for 60 min.

[0069] (4)PC 61 Fabrication of the BM electron transport layer: PC 61 BM was dissolved in CB solvent to prepare PC with a concentration of 20 mg / ml. 61 BM-CB solution, i.e., PC 61 BM electron transport layer precursor solution, PC 61 The BM electron transport layer precursor solution was spin-coated onto the perovskite light absorption layer prepared in step (3) at a speed of 2000 rpm for 30 s, and then annealed at 70 °C for 60 s to obtain a hole transport layer with a thickness of 100 nm.

[0070] (5) Preparation of BCP passivation layer: Dissolve BCP in IPA solvent to prepare 0.5 mg / ml BCP-IPA solution, i.e. BCP passivation layer precursor solution. Spin-coat the BCP passivation layer precursor solution onto the PC prepared in step (4). 61 On the BM electron transport layer, spin coating was performed at 4000 rpm for 30 s, followed by annealing at 100 °C for 60 s to obtain a passivation layer with a thickness of 10 nm.

[0071] (6) Preparation of Ag metal electrode: Place the sample prepared in step (5) into a vacuum evaporation coating device, and wait until the vacuum degree reaches 5×10⁻⁶. -4 After Pa, with and An Ag electrode coating with a thickness of 100 nm was deposited using an evaporation rate, resulting in a perovskite solar cell with an effective area of ​​0.04 cm². 2 .

[0072] Test characterization:

[0073] Under simulated AM1.5 sunlight conditions (light intensity 100 mW / cm²), 2The current-voltage curves (JV) of the perovskite solar cells prepared in Example 1 and Comparative Example 1 were tested respectively, with reverse scanning from 1.5V to 0.5V at a scan rate of 20mV / s. The results are shown in Table 1 and 20mV / s. Figure 5 .

[0074] From Table 1 and Figure 5 It can be seen that the J of perovskite solar cells treated with ultrasonic vibration... SC V OC Both the photoelectric efficiency and the photoelectric effect (FF) were improved. In Example 1, the photoelectric efficiency of the cell treated with ultrasonic vibration (22.05%) was higher than that of the cell in Comparative Example 1 that was not treated with ultrasonic vibration (19.88%), which proves that ultrasonic vibration treatment plays a role in improving the photoelectric performance of perovskite cells.

[0075] Table 1 Photoelectric performance parameters of various perovskite solar cells

[0076]

[0077] Figure 1 This is a scanning electron microscope image of the surface of the ultrasonically oscillated perovskite thin film prepared in Example 1. Figure 2 This is a scanning electron microscope image of the surface of the perovskite thin film prepared in Comparative Example 1 without ultrasonic vibration treatment. Figure 1 and Figure 2 The comparison shows that the perovskite film treated with ultrasonic vibration has larger grains and fewer grain boundaries.

[0078] Figure 3 The X-ray diffraction (XRD) patterns are shown for the perovskite films prepared by ultrasonic oscillation treatment in Example 1 and those prepared by Comparative Example 1 without ultrasonic oscillation treatment. The XRD pattern shows that the sample prepared by ultrasonic oscillation treatment in Example 1 has a stronger peak at (100), indicating that the perovskite film prepared by ultrasonic oscillation treatment has higher crystallinity and preferential orientation in the (100) plane.

[0079] Figure 4 The images show the photoluminescence spectra of the perovskite films prepared in Example 1 after ultrasonic oscillation treatment and those prepared in Comparative Example 1 without ultrasonic oscillation treatment. Figure 4 It can be seen that the emission intensity of the perovskite film after ultrasonic oscillation treatment is much higher than that of the perovskite film without ultrasonic oscillation treatment, indicating that ultrasonic oscillation treatment suppresses nonradiative recombination of charge carriers.

[0080] Figure 6 The images show the GIXRD patterns of the ultrasonically vibrated perovskite thin film prepared in Example 1 at different Ψ angles with an incident angle of 0.5°. Figure 7The GIXRD patterns of the perovskite thin film prepared in Comparative Example 1 without ultrasonic vibration treatment at different Ψ angles with an incident angle of 0.5° are shown. Figure 8 The perovskite film prepared by ultrasonic vibration treatment in Example 1 and the perovskite film prepared by Comparative Example 1 without ultrasonic vibration treatment. Linear fit plot of the curve. Comparison Figure 6 , Figure 7 and combined Figure 8 It can be seen that the residual stress of the perovskite film treated with ultrasonic vibration is significantly reduced.

[0081] Figure 9 Box plots show the photoelectric conversion efficiency of perovskite solar cells prepared in Example 1 with different ultrasonic power treatments and those prepared in Comparative Example 1 without ultrasonic oscillation treatment. Figure 9 It can be seen that ultrasonic oscillation treatment can significantly improve the photoelectric conversion efficiency of perovskite solar cells; and the photoelectric conversion efficiency of perovskite solar cells first increases and then decreases with the increase of ultrasonic power.

[0082] Figure 10 The graph shows the voltage versus light intensity of the perovskite solar cells prepared in Example 1 with ultrasonic oscillation treatment and those prepared in Comparative Example 1 without ultrasonic oscillation treatment. The slope of the perovskite solar cell prepared in Example 1 with ultrasonic oscillation treatment is less than that of the perovskite solar cell prepared in Comparative Example 1 without ultrasonic oscillation treatment, indicating that the defect-assisted recombination of the perovskite solar cell prepared in Example 1 with ultrasonic oscillation treatment is significantly reduced.

[0083] Figure 11 The graphs show the light stability of the perovskite solar cell devices prepared in Example 1 (under ultrasonic vibration treatment) and Comparative Example 1 (under no ultrasonic vibration treatment) at the maximum power point. It can be seen that the perovskite solar cell after ultrasonic vibration treatment still maintains more than 90% of the initial photoelectric conversion efficiency after aging for 250 hours, while the PCE of the perovskite solar cell device without ultrasonic vibration treatment rapidly decays to about 80% of the initial photoelectric conversion efficiency.

Claims

1. A method for preparing a perovskite thin film, characterized in that, Includes the following steps: (1) A perovskite wet film is prepared by coating a perovskite precursor solution onto a substrate and then gas-quenching the perovskite wet film. Before the spin coating of the perovskite precursor solution is completed, the perovskite wet film is subjected to gas quenching. The gas quenching process involves drying the perovskite wet film under a nitrogen gas flow, followed by annealing at 50-250°C for 1-600 minutes. (2) The gas-quenched perovskite wet film is subjected to ultrasonic vibration treatment to induce cavitation effect and enhanced micro-mixing in the gas-quenched perovskite wet film, so as to regulate the nucleation and crystallization process of the perovskite film. Then, the film is annealed to obtain the perovskite film.

2. The preparation method according to claim 1, characterized in that, The coating process involves spin coating at 1000-12000 rpm for 5-600 seconds.

3. The preparation method according to claim 1, characterized in that, The ultrasonic oscillation power is 0.1~100 W, and the time is 10 s~60 min.

4. The preparation method according to claim 1, characterized in that, In step (2), the annealing temperature is 50~250℃ and the time is 1~600 min.

5. The perovskite thin film prepared by the preparation method according to any one of claims 1-4.

6. A perovskite solar cell, comprising a perovskite light-absorbing layer, characterized in that, The perovskite light-absorbing layer is the perovskite thin film as described in claim 5.

7. The perovskite solar cell according to claim 6, characterized in that, The perovskite solar cell is an inverted structure, comprising, from bottom to top, a conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and a metal electrode.

8. The perovskite solar cell according to claim 7, characterized in that, The perovskite light-absorbing layer is FA. 1-x Cs x PbI 3-y Br y Thin film, where 0 < x < 1, 0 < y < 3, or FA 1-x-z MA z Cs x PbI 3-y Br y A thin film, wherein 0 < x < 1, 0 < y < 3, 0 < z < 1, and the thickness of the perovskite light-absorbing layer is 100~5000 nm.

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