Perovskite thin film, method for preparing the same, and perovskite solar cell

Abstract

The application provides a perovskite thin film, a preparation method thereof and a perovskite solar cell. The perovskite thin film is obtained through first annealing treatment and second annealing treatment of a mixed solution composed of a perovskite precursor, a solvent and a crosslinking agent, the temperature of the first annealing treatment is 70-110 DEG C or 150-200 DEG C, and the temperature of the second annealing treatment is 90-160 DEG C. Through the two-step annealing treatment and by controlling the temperature difference between the first annealing treatment and the second annealing treatment to be not less than 15 DEG C, the perovskite thin film has large grain size, few grain boundaries and good crystallinity, and can be used for preparing a perovskite solar cell, so that the efficiency and stability of the perovskite solar cell can be effectively improved.

Description

Technical Field

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

[0002] Organic-inorganic hybrid perovskite solar cells possess excellent photovoltaic properties and are expected to become a new generation of commercial photovoltaic materials. Currently, the key to achieving high-performance perovskite solar cells lies in the crystallinity of the perovskite thin film. To achieve controllable preparation of high-performance perovskite thin films, additives such as MACl and NH4Cl are often added to the perovskite precursor solution to regulate the annealing and crystallization process of the perovskite thin film, thereby obtaining a perovskite thin film with good crystallinity, and thus obtaining a high-performance perovskite solar cell.

[0003] Thermal annealing is a crucial step in the formation of perovskite thin films. Current technologies typically employ a single-step high-temperature annealing process, but this can lead to problems with molecular weight absorption (MA). + Plasma volatilization leaves residues and residual stress in the perovskite lattice, resulting in poor crystallinity and excessive grain boundaries, which significantly affects the photovoltaic performance and stability of perovskite solar cells. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a perovskite thin film, a method for preparing the same, and a perovskite solar cell. The perovskite thin film exhibits good crystallinity and few grain boundary defects, which can effectively improve the efficiency and stability of perovskite solar cells.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a perovskite thin film, which is obtained by sequentially subjecting a mixed solution composed of a perovskite precursor, a solvent and a crosslinking agent to a first annealing treatment and a second annealing treatment.

[0007] The temperature of the first annealing treatment is 70-110℃ or 150-200℃, and the temperature of the second annealing treatment is 90-160℃;

[0008] The temperature difference between the first annealing treatment and the second annealing treatment is not less than 15°C.

[0009] Preferably, the perovskite precursor comprises a first component and a second component, wherein the first component is selected from any one or more of PbI2, PbF2, PbCl2, PbBr2, SnI2, SnF2, SnCl2 or SnBr2, and the second component is selected from methylamine halide salts and / or formamidinium halide salts.

[0010] Preferably, the solvent includes dimethylformamide.

[0011] Preferably, the crosslinking agent includes MACl and / or NH4Cl.

[0012] Secondly, the present invention provides a method for preparing a perovskite thin film, comprising the following steps:

[0013] (1) A perovskite precursor solution is deposited on a substrate and at least part of the solvent is removed to obtain a perovskite thin film precursor.

[0014] (2) The perovskite film precursor is subjected to a first annealing treatment at 70-110°C or 150-200°C, and then subjected to a second annealing treatment at 90-160°C, thereby forming the perovskite film on the substrate.

[0015] Preferably, the perovskite precursor solution includes a perovskite precursor, a solvent, and a crosslinking agent.

[0016] Preferably, the temperature difference between the first annealing treatment and the second annealing treatment is not less than 15°C.

[0017] More preferably, the temperature difference between the first annealing treatment and the second annealing treatment is not less than 30°C.

[0018] More preferably, the temperature difference between the first annealing treatment and the second annealing treatment is not less than 50°C.

[0019] Preferably, the first annealing process takes 1 to 10 minutes.

[0020] Preferably, the second annealing process takes 10 to 60 minutes.

[0021] Preferably, the perovskite precursor comprises a first component and a second component, wherein the first component is selected from any one or more of PbI2, CsBr, PbF2, PbCl2, PbBr2, SnI2, SnF2, SnCl2 or SnBr2, and the second component is selected from methylamine halide salts and / or formamidinium halide salts.

[0022] Preferably, the solvent includes dimethylformamide.

[0023] Preferably, the crosslinking agent includes MACl and / or NH4Cl.

[0024] Preferably, the concentration of the crosslinking agent in the perovskite precursor solution is 0.05–0.5 M.

[0025] Preferably, the perovskite precursor solution is applied to the substrate by spin coating, blade coating, slot coating, spraying, or dip coating.

[0026] Preferably, the removal of at least part of the solvent specifically involves removing at least part of the solvent from the perovskite precursor solution using vacuum and / or anti-solvent methods.

[0027] Thirdly, the present invention provides a perovskite solar cell, comprising at least a hole transport layer, a perovskite layer and an electron transport layer stacked sequentially, wherein the perovskite layer includes the perovskite thin film involved in the above technical solution.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] This invention provides a perovskite thin film. The perovskite thin film, after partial solvent removal from a perovskite precursor solution, first undergoes a first-step annealing treatment to induce rapid escape of the crosslinking agent, followed by a second-step annealing treatment to achieve annealing crystallization at normal temperature. The temperature difference between the first and second annealing steps is controlled to be no less than 15°C, which can repair defects left by the escape of the crosslinking agent caused by one-step high-temperature annealing. The resulting perovskite thin film has a relatively large grain size (no less than 500 nm), effectively improving the crystallinity of the perovskite thin film and reducing grain boundaries. When used to prepare perovskite solar cells, it can effectively improve their efficiency and stability. Attached Figure Description

[0030] Figure 1 Here is a SEM image of the perovskite film in Example 1;

[0031] Figure 2 Here is a SEM image of the perovskite film in Example 2;

[0032] Figure 3 The JV curves of the perovskite solar cells obtained in Example 1 and Comparative Example 1 are shown.

[0033] Figure 4 The JV curves of the perovskite solar cells obtained in Example 2 and Comparative Example 2 are shown.

[0034] Figure 5 The JV curve of the perovskite solar cell obtained in Example 3 is shown below.

[0035] Figure 6 The JV curve of the perovskite solar cell obtained in Example 4 is shown.

[0036] Figure 7 This is a comparison chart of the stability test results of the perovskite solar cells obtained in Example 1 and Comparative Example 1. Detailed Implementation

[0037] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] To address the problem of poor crystallinity and excessive grain boundaries in existing perovskite thin films, which significantly affect the photovoltaic performance and stability of perovskite solar cells, this invention provides a perovskite thin film obtained by sequentially subjecting a mixed solution composed of a perovskite precursor, a solvent, and a crosslinking agent to a first annealing treatment and a second annealing treatment. In this invention, the temperature of the first annealing treatment is 70–110°C or 150–200°C, and the temperature of the second annealing treatment is 90–160°C. The temperature difference between the first and second annealing treatments is not less than 15°C. In some embodiments of this invention, the perovskite precursor comprises a first component and a second component. The first component is selected from any one or more of PbI2, CsBr, PbI2, PbCl2, PbBr2, SnI2, SnI2, SnCl2, or SnBr2, and the second component is selected from methylamine halide salts and / or formamidinium halide salts (general formula can be represented as "B"). + X - “B” + Selected from FA + or MA + X - Selected from I - Cl - ,Br - or F - The solvent includes dimethylformamide, and the crosslinking agent includes MACl and / or NH4Cl, or other conventional crosslinking agents such as ammonium phosphate, trimethylammonium chloride, or formamide. Studies have shown that the average grain size in the perovskite film is not less than 500 nm. The perovskite film provided by this invention has an ABX3 type crystal structure, wherein A is an organic cation (such as MACl, NH4Cl, or NH4Cl). + FA + ) or inorganic cations (such as Cs) + (), or a mixture of organic and inorganic cations; B is a divalent metal ion, such as Pb. 2+ or Sn 2+ X is any one or more of I, Br, Cl, or F.

[0039] Research has shown that the perovskite thin film provided by this invention (with...) Figure 1(For example) Large grain size and fewer grain boundaries are used to prepare perovskite solar cells, which can effectively improve the working efficiency and stability of solar cells.

[0040] The present invention also provides a method for preparing the above-mentioned perovskite thin film, comprising the following steps:

[0041] (1) A perovskite precursor solution is deposited on a substrate and at least part of the solvent is removed to obtain a perovskite thin film precursor.

[0042] (2) The perovskite film precursor is subjected to a first annealing treatment at 70-110°C or 150-200°C, and then subjected to a second annealing treatment at 90-160°C, thereby forming the perovskite film on the substrate.

[0043] In this invention, a perovskite precursor solution is first provided, comprising a perovskite precursor, a solvent, and a crosslinking agent. The selection of the perovskite precursor, solvent, and crosslinking agent is as described in the relevant content of the above technical solution and will not be repeated here. The concentration of the perovskite precursor in the perovskite precursor solution is 0.5M to 1.5M, and the concentration of the crosslinking agent in the perovskite precursor solution is 0.05M to 0.5M. Then, the perovskite precursor solution is coated onto a substrate, and at least part of the solvent is removed to obtain a perovskite thin film precursor. In some embodiments of this invention, the perovskite precursor solution can be coated onto the substrate by spin coating, blade coating, slot coating, spraying, or dip coating. This invention does not have any particular limitations on spin coating, blade coating, slot coating, spraying, or dip coating; any operation can be performed using techniques well known to those skilled in the art. In some embodiments of the present invention, the removal of at least part of the solvent specifically involves removing at least part of the solvent from the perovskite precursor solution by means of vacuuming and / or antisolventing to obtain a perovskite thin film precursor.

[0044] After obtaining the perovskite film precursor, the perovskite film precursor is first subjected to a first annealing treatment at 70–110°C or 150–200°C for 1–10 min, and then subjected to a second annealing treatment at 90–160°C for 10–60 min, thereby forming the perovskite film on the substrate. In some embodiments of the present invention, the temperature difference between the first annealing treatment and the second annealing treatment is not less than 15°C, preferably not less than 30°C, and more preferably not less than 50°C. In some embodiments of the present invention, the first annealing treatment uses a higher temperature than the second annealing treatment, which can achieve the beneficial effect of reducing the residue of crosslinking agent.

[0045] Thermal annealing plays a crucial role in the growth of perovskite crystals. This invention employs a two-step thermal annealing process, controlling the temperature difference between the first and second annealing steps to be no less than 15°C. The first annealing step induces the rapid escape of the crosslinking agent, followed by the second annealing step, achieving annealed crystallization of the perovskite crystals at normal temperatures. This addresses the defects caused by the escape of the crosslinking agent in the one-step high-temperature annealing (200–400°C) method of existing technologies. The resulting perovskite film has a relatively large average grain size, no less than 500 nm, effectively improving its crystallinity and reducing grain boundaries. This makes it suitable for fabricating perovskite solar cells, effectively improving their efficiency and stability.

[0046] Based on this, the present invention also provides a perovskite solar cell, which includes at least a hole transport layer, a perovskite layer, and an electron transport layer stacked sequentially, wherein the perovskite layer comprises the aforementioned perovskite thin film. In some embodiments of the present invention, the hole transport layer may be selected from any one or more of spiro-MeOTAD, NiOx, or CuOx (x≤1), and the electron transport layer may be selected from any one or more of C60, SnO2, or ZnO.

[0047] The present invention also provides a method for preparing the above-mentioned perovskite solar cell, comprising the following steps:

[0048] Provide a conductive substrate;

[0049] A first transport layer is formed on the surface of the conductive substrate;

[0050] Using the perovskite thin film preparation method described in the above technical solution, a perovskite thin film is formed on the surface of the first transport layer as a perovskite layer;

[0051] A second transport layer is formed on the surface of the perovskite layer;

[0052] Finally, conductive electrodes are constructed on the surface of the second transport layer.

[0053] It should be noted that the conductivity characteristics of the first transport layer and the second transport layer are opposite. That is, when the first transport layer is an electron transport layer, the second transport layer is a hole transport layer, and vice versa.

[0054] In this invention, the perovskite solar cell can be a forward or reverse structure. Its structure is as follows: a conductive substrate / hole or electron transport layer / perovskite layer / electron or electron transport layer with opposite conductivity to the aforementioned hole or electron transport layer / electron electrode, stacked sequentially. The materials and thicknesses of each layer are preferably as follows: the conductive substrate is selected from FTO conductive glass or ITO conductive glass, wherein the FTO conductive glass thickness is approximately 300 nm and the ITO conductive glass thickness is approximately 150 nm; the electron transport layer is selected from any one or more of C60, SnO2, or ZnO, with a thickness of 5-100 nm; the perovskite layer is preferably 5-100 nm thick, with a thickness of 200-1500 nm; the hole transport layer is any one or more of spiro-MeOTAD, NiOx, or CuOx, with a thickness of 5-100 nm; the electrode can be a metal electrode or an oxide electrode, where the metal electrode includes, but is not limited to, Au, Ag, Cu, or Al, and the oxide electrode includes, but is not limited to, ITO, FTO, SnO2, or Al2O3.

[0055] The above-mentioned layers can be prepared using methods well known to those skilled in the art, such as: the conductive substrate can be prepared using physical vapor deposition, evaporation or sputtering; the electron transport layer and hole transport layer can be prepared using any one of spin coating, spray coating or blade coating; the perovskite layer can be prepared using the above-mentioned perovskite thin film preparation methods; and the conductive electrode can be prepared using vacuum evaporation or vacuum sputtering.

[0056] To further illustrate the present invention, the following embodiments are provided for detailed description. The source of the experimental materials used in the following embodiments of the present invention is not particularly limited; they can be purchased from the market or prepared according to conventional preparation methods well known to those skilled in the art.

[0057] Example 1

[0058] This embodiment provides a perovskite solar cell, the fabrication method of which is as follows:

[0059] (1) A 1*1cm FTO thin film (glass thickness 2mm, FTO film thickness 100nm) was cleaned with ethanol, isopropanol (IPA), and acetone for 30min each, and then dried with a nitrogen gun. A dense NiOx thin film (thickness 20nm, x≤1) was sputtered onto the surface of the FTO thin film glass using magnetron sputtering at a power of 80W for 30min. The sputtered film was then treated with oxygen plasma for 10min at a power of 2kW.

[0060] (2) Weigh 4.61g PbI2 and 1.50g MAI and dissolve them in 6mL DMF. Heat and stir at 70℃ for 15min to fully dissolve them. Then add 0.2M MACl (4.08mg) to obtain a perovskite precursor solution. Take 50μL of the perovskite precursor solution and spread it evenly on the film obtained in step (1). When spin-coating, set the spin coater parameters to 4000rpm / s acceleration, 3700rpm rotation speed, and 30s time. When the spin-coating time reaches 7s, take 1mL of chlorobenzene solution and quickly drop it onto the spin coater. After spin-coating, place the film on a 70℃ hot plate for annealing for 3min. Then transfer the film to a 130℃ hot plate for annealing for 15min to obtain a perovskite film (380nm).

[0061] (3) A C60 electron transport layer (40 nm) is deposited on the surface of the perovskite thin film prepared above;

[0062] (4) The product obtained in step (3) is transferred to a thermal evaporation equipment, and an electrode (Au) is deposited in the C60 electron transport layer under a vacuum of 1×10-5 Pa with a thickness of 100 nm to obtain a perovskite solar cell.

[0063] The surface SEM image of the perovskite thin film prepared in this embodiment is shown below. Figure 1 As shown, the crystal grains are relatively large, with a size of about 500 to 700 nm.

[0064] Example 2

[0065] This embodiment provides a perovskite solar cell, the fabrication method of which is as follows:

[0066] (1) A 1*1cm FTO thin film (glass thickness 2mm, FTO film thickness 100nm) was cleaned with ethanol, isopropanol (IPA), and acetone for 30min each, and then dried with a nitrogen gun. A dense NiO layer was sputtered onto the surface of the FTO thin film glass using magnetron sputtering. x Thin film (thickness 20 nm, x ≤ 1), sputtered at 80 W for 30 min. The sputtered film was then treated with oxygen plasma for 10 min at 2 kW.

[0067] (2) Prepare a perovskite layer precursor solution with a mass fraction of 20% (CsBr: 0.15mol / L, PbI2: 1mol / L, FAI: 0.85mol / L, NH4Cl: 0.3mol / L), using DMF as the solvent. Take 50μL of the perovskite precursor solution and spread it evenly on the film obtained in step (1). When spin-coating, set the spin coater parameters to an acceleration of 4000rpm / s, a rotation speed of 3500rpm, and a time of 40s. Then transfer the spin-coated wet film to a vacuum device, quickly evacuate to below 20Pa and hold for 20s, then remove the film and place it on a 180℃ hot stage for annealing for 2 min. Then transfer the film to a 130℃ hot stage for annealing for 15 min to obtain a perovskite film (380nm).

[0068] (3) A C60 electron transport layer (40 nm) is deposited on the surface of the perovskite thin film prepared above;

[0069] (4) Transfer the product obtained in step (3) to a thermal evaporation equipment, where the vacuum level reaches 1×10⁻⁶. -5 Perovskite solar cells were obtained by evaporating an electrode (Au) with a thickness of 100 nm in a C60 electron transport layer under Pa conditions.

[0070] Example 3

[0071] This embodiment provides a perovskite solar cell, the fabrication method of which is as follows:

[0072] (1) A 1*1cm FTO thin film (glass thickness 2mm, FTO film thickness 100nm) was cleaned with ethanol, isopropanol (IPA), and acetone for 30min each, and then dried with a nitrogen gun. A dense NiOx thin film (thickness 20nm, x≤1) was sputtered onto the surface of the FTO thin film glass using magnetron sputtering at a power of 80W for 30min. The sputtered film was then treated with oxygen plasma for 10min at a power of 2kW.

[0073] (2) Weigh 4.61g PbI2 and 1.50g MAI and dissolve them in 6mL DMF. Heat and stir at 70℃ for 15min to fully dissolve them. Add 0.2M MACl (4.08mg) to obtain a perovskite precursor solution. Take 50μL of the perovskite precursor solution and spread it evenly on the film obtained in step (1). When spin-coating, set the spin coater parameters to 4000rpm / s acceleration, 3700rpm rotation speed, and 30s time. When the spin-coating time reaches 7s, take 1mL of chlorobenzene solution and quickly drop it onto the spin coater. After spin-coating, place the film on a 115℃ hot stage for annealing for 3min. Then transfer the film to a 130℃ hot stage for annealing for 15min to obtain a perovskite film (380nm).

[0074] (3) A C60 electron transport layer (40 nm) is deposited on the surface of the perovskite thin film prepared above;

[0075] (4) The product obtained in step (3) is transferred to a thermal evaporation equipment, and an electrode (Au) is deposited in the C60 electron transport layer under a vacuum of 1×10-5 Pa with a thickness of 100 nm to obtain a perovskite solar cell.

[0076] Example 4

[0077] This embodiment provides a perovskite solar cell, the fabrication method of which is as follows:

[0078] (1) A 1*1cm FTO thin film (glass thickness 2 mm, FTO film thickness 100nm) was cleaned with ethanol, isopropanol (IPA), and acetone for 30 min each, and then dried with a nitrogen gun. A dense NiO layer was sputtered onto the surface of the FTO thin film glass using magnetron sputtering. x Thin film (thickness 20 nm, x ≤ 1), sputtered at 80 W for 30 min. The sputtered film was then treated with oxygen plasma for 10 min at 2 kW.

[0079] (2) Prepare a perovskite layer precursor solution with a mass fraction of 20% (CsBr: 0.15mol / L, PbI2: 1mol / L, FAI: 0.85mol / L, NH4Cl: 0.3mol / L), using DMF as the solvent. Take 50μL of the perovskite precursor solution and spread it evenly on the film obtained in step (1). When spin-coating, set the spin coater parameters to an acceleration of 500rpm / s, a rotation speed of 3500rpm, and a time of 40s. Then transfer the spin-coated wet film to a vacuum device, quickly evacuate to below 20Pa and hold for 20s, then remove the film and anneal it on a hot stage at 160℃ for 2 min. Then transfer the film to a hot stage at 130℃ for annealing for 15 min to obtain a perovskite film (380nm).

[0080] (3) A C60 electron transport layer (40 nm) is deposited on the surface of the perovskite thin film prepared above;

[0081] (4) Transfer the product obtained in step (3) to a thermal evaporation equipment, where the vacuum level reaches 1×10⁻⁶. -5 Perovskite solar cells were obtained by evaporating an electrode (Au) with a thickness of 100 nm in a C60 electron transport layer under Pa conditions.

[0082] Comparative Example 1

[0083] This comparative example provides a perovskite solar cell, which differs from Example 1 only in that, after spin coating in step (2), the spin-coated film is directly annealed on a hot stage at 130°C for 18 minutes. The other parameters and steps are the same as in Example 1.

[0084] The surface SEM image of the perovskite thin film prepared in this comparative example is shown below. Figure 2 As shown, the crystal grains are relatively small, with a size of about 100 to 300 nm.

[0085] Comparative Example 2

[0086] This comparative example provides a perovskite solar cell, which differs from Example 2 only in that, after spin coating in step (2), the spin-coated film is directly annealed on a hot stage at 130°C for 15 minutes. The other parameters and steps are the same as in Example 2.

[0087] Performance testing

[0088] The perovskite solar cells obtained in the examples and comparative examples were tested for performance using the following methods:

[0089] The current density-voltage (JV) curves of the cells prepared in the PCE test examples and comparative examples were obtained. The tests were performed on a Kethley 2400 system; test conditions: simulated light intensity of 100 mW / cm². -2 (AM1.5G) scan rate is 0.1Vs -1 (Step size 0.02V, time delay 200ms), scan range 1.2V to -0.2V, xenon lamp power output calibrated by NERL (National Renewable Energy Laboratory) standard KG5 Si cell 2.

[0090] The test results are shown in Table 1 below. Figures 3-6 As shown:

[0091] Table 1

[0092]

[0093]

[0094] Figure 3 The graphs show the JV curves of the perovskite solar cells obtained in Example 1 and Comparative Example 1. Figure 4 The graphs show the JV curves of the perovskite solar cells obtained in Example 2 and Comparative Example 2. Figure 5 This is the JV curve of the perovskite solar cell obtained in Example 3. Figure 6 This is a JV curve diagram of the perovskite solar cell obtained in Example 4. Based on the data in Table 1, combined with... Figures 3-6 It can be seen that the open-circuit voltage, short-circuit current, fill factor and final efficiency of the perovskite solar cell provided by the embodiments of the present invention are significantly improved, indicating that the defects in the perovskite thin film are significantly reduced and the device performance is significantly optimized.

[0095] The stability of the perovskite solar cells obtained in Example 1 and Comparative Example 1 was tested using the following methods:

[0096] The current density-voltage (JV) curves of the batteries prepared using the PCE test examples and comparative examples were obtained. The tests were performed on a Kethley 2400 system. The test conditions were as follows: simulated light intensity of 100 mW cm⁻² (AM 1.5G), scan rate of 0.1 Vs⁻¹ (step size of 0.02 V, time delay of 200 ms), scan range of 1.2 V to -0.2 V, and the power output of the xenon lamp was calibrated to the KG5 standard Si battery of the NERL (National Renewable Energy Laboratory) standard.

[0097] The results are as follows Figure 7 As shown, the perovskite solar cell provided by the present invention does not show a significant decrease in photoelectric conversion efficiency after 500 cycles, while the perovskite solar cell provided by Comparative Example 1 shows a more obvious decreasing trend after 200 cycles, indicating that the perovskite solar cell provided by the present invention has excellent working stability.

[0098] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A perovskite thin film, characterized in that, The mixture of perovskite precursor, solvent and crosslinking agent is obtained by sequentially passing a first annealing treatment and a second annealing treatment. The temperature of the first annealing treatment is 160~200℃, and the temperature of the second annealing treatment is 90~160℃; the time of the first annealing treatment is 1~10 min; and the time of the second annealing treatment is 10~60 min. The temperature difference between the first annealing treatment and the second annealing treatment is not less than 30°C; The temperature of the first annealing treatment is higher than the temperature of the second annealing treatment; The concentration of the crosslinking agent in the perovskite precursor solution is 0.05~0.5M; The crosslinking agent includes MACl and / or NH4Cl; The perovskite precursor includes a first component and a second component. The first component is selected from any one or more of PbI2, PbF2, PbCl2, PbBr2, SnI2, SnF2, SnCl2 or SnBr2, and the second component is selected from methylamine halide salts and / or formamidinium halide salts. The solvent includes dimethylformamide.

2. A method for preparing a perovskite thin film as described in claim 1, characterized in that, Includes the following steps: (1) The perovskite precursor solution is coated onto the substrate, and at least part of the solvent is removed to obtain the perovskite thin film precursor; (2) The perovskite film precursor is subjected to a first annealing treatment at 160~200°C and then a second annealing treatment at 90~160°C to form the perovskite film on the substrate. The temperature of the first annealing treatment is higher than the temperature of the second annealing treatment; The concentration of the crosslinking agent in the perovskite precursor solution is 0.05~0.5M; The temperature difference between the first annealing treatment and the second annealing treatment is not less than 30°C; The perovskite precursor solution includes a perovskite precursor, a solvent, and a crosslinking agent.

3. The preparation method according to claim 2, characterized in that, The temperature difference between the first annealing treatment and the second annealing treatment is not less than 50°C.

4. The preparation method according to claim 2, characterized in that, The perovskite precursor includes a first component and a second component. The first component is selected from any one or more of PbI2, CsBr, PbF2, PbCl2, PbBr2, SnI2, SnF2, SnCl2 or SnBr2, and the second component is selected from methylamine halide salts and / or formamidinium halide salts. The solvent includes dimethylformamide; The crosslinking agent includes MACl and / or NH4Cl.

5. The preparation method according to claim 2, characterized in that, The perovskite precursor solution is applied to the substrate by spin coating, blade coating, slot coating, spraying or dip coating. The removal of at least part of the solvent specifically involves removing at least part of the solvent from the perovskite precursor solution using vacuum and / or anti-solvent methods.

6. A perovskite solar cell, characterized in that, It includes at least a hole transport layer, a perovskite layer and an electron transport layer stacked sequentially, wherein the perovskite layer includes the perovskite film according to claim 1 or the perovskite film prepared by the preparation method according to any one of claims 2 to 5.

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