Perovskite thin film, trans-perovskite solar cell and preparation method

Abstract

The invention belongs to the photovoltaic field, and particularly relates to a perovskite thin film, a trans-perovskite solar cell and a preparation method. The preparation method of the perovskite thin film comprises the steps of firstly coating a perovskite precursor solution, and then sequentially carrying out back coating annealing and front surface annealing to prepare the perovskite thin film. According to the perovskite thin film prepared in a mode of combining back-covering annealing and front-surface annealing, the crystallization quality and the film forming quality of the perovskite thin film can be effectively improved, and then the photoelectric property of the perovskite solar cell is improved.

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaics, and in particular relates to a perovskite film, an inverse perovskite solar cell and a preparation method thereof. Background Art

[0002] The rapid development of perovskite solar cells marks a revolution in the field of third-generation photovoltaic research. High-efficiency organic-inorganic hybrid perovskite solar cells have become one of the most promising light-absorbing materials due to their excellent optoelectronic properties, such as long carrier diffusion length and high absorption coefficient. With continuous technological innovation and device optimization, the certified photoelectric conversion efficiency (PCE) of perovskite solar cells has increased from 3.8% to 26.1%. Therefore, perovskite solar cells are becoming the most advantageous alternative to crystalline silicon solar cells.

[0003] However, the commercial development of wide-bandgap perovskite solar cells is hampered by their poor humidity and air stability. Wide-bandgap perovskite solar cells reported in the prior art are not only not susceptible to environmental factors but also show excellent performance as the top layer of tandem cells. However, there are few preparation technologies for wide-bandgap perovskite films in the prior art, and the base perovskite film in the inverted perovskite solar cell suffers from large performance losses (especially fill factor) due to film problems such as crystallinity.

[0004] On the one hand, the existing technology mainly regulates the crystallization of perovskite films by doping, but this will introduce other defects and even cause the original band gap of 2.3eV to change, which is not conducive to the preparation of subsequent stacked perovskite solar cells; on the other hand, the existing technology mainly uses low-temperature annealing to regulate the crystallization of perovskite films, but this annealing method causes the crystallization quality of perovskite films to be seriously reduced due to incomplete nucleation or too rapid crystallization.

[0005] Therefore, there is an urgent need to develop a method for preparing perovskite films that can effectively improve the crystallization quality of perovskite films and thereby enhance the photoelectric performance of perovskite solar cells. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a perovskite film, an inverted perovskite solar cell and a preparation method. The perovskite film prepared by combining back annealing and front annealing can effectively improve the crystallization quality and film quality of the perovskite film, thereby improving the photoelectric performance of the perovskite solar cell.

[0007] Specifically, the present invention provides a method for preparing a perovskite film, the preparation method comprising: first coating a perovskite precursor solution, and then sequentially performing back annealing and front annealing to obtain the perovskite film.

[0008] In one or more embodiments, the perovskite precursor solution comprises a perovskite structural material and a solvent.

[0009] In one or more embodiments, the chemical formula of the perovskite structured material is ABX3, A is a formamidinium ion and / or a cesium ion; B is a lead ion; and X is a bromide ion and / or an iodide ion.

[0010] In one or more embodiments, in the perovskite precursor solution, the solvent is selected from one or more of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone and tetramethylene sulfoxide.

[0011] In one or more embodiments, in the perovskite precursor solution, the concentration of the perovskite structure substance is 1.4-2.0 mol / L.

[0012] In one or more embodiments, the coating method is spin coating, knife coating or slot coating.

[0013] In one or more embodiments, the back annealing temperature is 120-130°C.

[0014] In one or more embodiments, the back annealing time is 10-300s.

[0015] In one or more embodiments, the front side annealing temperature is 130-150°C.

[0016] In one or more embodiments, the front annealing time is 15-20 minutes.

[0017] In one or more embodiments, the back annealing time is 90-120 seconds.

[0018] The invention provides a perovskite film prepared by the preparation method of the invention.

[0019] In one or more embodiments, the perovskite film has a thickness of 600-700 nm.

[0020] In one or more embodiments, the perovskite film comprises a perovskite structure material, the chemical formula of the perovskite structure material is ABX3, A is a formamidinium ion and / or a cesium ion; B is a lead ion; and X is a bromide ion and / or an iodide ion.

[0021] The present invention provides an inverted perovskite solar cell comprising the perovskite film of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1Schematic diagram of back annealing in some embodiments of the present invention, 1 is a transparent conductive substrate, 2 is a hole transport layer, and 3 is a perovskite film. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0024] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0025] Herein, “comprising”, “including”, “containing” and similar terms encompass the meanings of “consisting essentially of” and “consisting of”. For example, when “A comprises B and C” is disclosed herein, “A consists essentially of B and C” and “A consists of B and C” should be deemed to be disclosed herein.

[0026] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0027] In this document, unless otherwise specified, percentage refers to mass percentage and ratio refers to mass ratio.

[0028] Herein, when describing embodiments or examples, it should be understood that they are not used to limit the present invention to these embodiments or examples. On the contrary, all substitutes, improvements and equivalents of the methods and materials described in the present invention can be included in the scope limited by the claims.

[0029] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0030] The present invention provides a method for preparing a perovskite film, the preparation method comprising first coating a perovskite precursor solution, and then sequentially performing back annealing and front annealing to obtain a perovskite film. In the present invention, the back annealing is performed with the film surface facing downward. In the present invention, the annealing is performed by combining the back annealing and the front annealing.

[0031] In the present invention, the perovskite precursor solution may include a perovskite structure substance and a solvent. In the perovskite precursor solution of the present invention, the chemical formula of the perovskite structure substance is ABX3, and A may be a formamidinium ion (FA + ) and / or cesium ions (Cs + ); B may be a lead ion; X may be a bromide ion and / or an iodide ion, such as FAPbBr3, FAPbI3, FA 0.83 Cs 0.17 PbI3、FA 0.90 Cs 0.10 The perovskite structure material of the present invention can be applied to coating without anti-solvent method.

[0032] In the perovskite precursor solution of the present invention, the solvent may be one or more selected from N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP) and tetramethylene sulfoxide (TMSO). In some embodiments, the volume ratio of DMF and NMP may be (0.66-4):1, for example, 4:1, 3:2, 2:3. In some embodiments, the volume ratio of DMF and DMSO may be (0.66-4):1, for example, 4:1, 3:2, 2:3. In some embodiments, the volume ratio of DMF and TMSO may be (0.66-4):1, for example, 4:1, 3:2, 2:3. In the present invention, the volume ratio of the solvent is controlled to the above-mentioned volume ratio, which is conducive to improving the crystallization quality of the perovskite film, and thus improving the perovskite film preparation method of the photoelectric performance of the perovskite solar cell.

[0033] In the perovskite precursor solution of the present invention, the concentration of the perovskite structure substance can be 1.4-2.0 mol / L, for example, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2.0 mol / L.

[0034] The method of coating the perovskite precursor solution of the present invention is an anti-solvent-free method. In the present invention, the method of coating the perovskite precursor solution can be spin coating, blade coating or slit coating.

[0035] In the present invention, the temperature of the back annealing can be 120-130°C, such as 120°C, 122°C, 124°C, 126°C, 128°C, 130°C. In the present invention, the time of the back annealing can be 10-300s, preferably 90-120s, such as 90s, 95s, 100s, 105s, 110s, 115s, 120s. In the present invention, the temperature of the front annealing can be 130-150°C, such as 130°C, 135°C, 140°C, 145°C, 150°C. In the present invention, the time of the front annealing can be 15-20min, such as 15min, 16min, 17min, 18min, 19min, 20min.

[0036] The present invention provides a perovskite film prepared by the method of the present invention, wherein the thickness of the perovskite film can be 600-700nm, for example, 600nm, 620nm, 640nm, 660nm, 680nm, 700nm. The perovskite film can contain a perovskite structural material, the chemical formula of the perovskite structural material is ABX3, and A can be a formamidinium ion (FA + ) and / or cesium ions (Cs + ); B may be a lead ion; X may be a bromide ion and / or an iodide ion, such as FAPbBr3, FAPbI3, FA 0.83 Cs 0.17 PbI3、FA 0.90 Cs 0.10 PbI3.

[0037] The present invention provides an inverted perovskite solar cell comprising a perovskite film of the present invention. The inverted perovskite solar cell of the present invention may be an inverted single-junction perovskite solar cell or an inverted stacked perovskite solar cell. In the present invention, the inverted single-junction perovskite solar cell may sequentially include a transparent conductive substrate, a hole transport layer, a perovskite film, an electron transport layer and a back electrode. In the present invention, the inverted single-junction perovskite solar cell may further include a hole blocking layer, wherein the hole blocking layer is between the electron transport layer and the back electrode. In the present invention, the inverted single-junction perovskite solar cell may further include a passivation layer, wherein the passivation layer is between the perovskite film and the electron transport layer. In some embodiments, the inverted single-junction perovskite solar cell sequentially includes a transparent conductive substrate, a hole transport layer, a perovskite film, an electron transport layer, a hole blocking layer and a back electrode.

[0038] In the present invention, the inverted stacked perovskite solar cell may include a bottom electrode, a bottom cell, an intermediate layer, an inverted perovskite top cell and a top electrode in sequence, and the inverted top cell may include a hole transport layer, a perovskite film and an electron transport layer in sequence. In the present invention, the inverted stacked perovskite solar cell may further include a hole blocking layer, and the hole blocking layer is between the electron transport layer and the top electrode. In the present invention, the inverted stacked perovskite solar cell may further include a passivation layer, and the passivation layer is between the perovskite film and the electron transport layer. In some embodiments, the inverted top cell of the inverted stacked perovskite solar cell includes a hole transport layer, a perovskite film, an electron transport layer and a hole blocking layer in sequence. In some embodiments, the inverted stacked perovskite solar cell may be a crystalline silicon / perovskite stacked solar cell.

[0039] In the present invention, the transparent conductive substrate may be indium tin oxide (ITO) glass and / or fluorine-doped tin oxide (FTO) glass.

[0040] In the present invention, the hole transport layer can be a self-assembled monomolecule (SAM), preferably, the hole transport layer can be (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz) and / or 3-(7-(4-(bis(4-methoxyphenyl)amino)-2-fluorophenyl)thiadiazole-4-yl)-2-cyanoacrylic acid.

[0041] In the present invention, the electron transport layer may be fullerene (C60) and / or a fullerene derivative (PCBM).

[0042] In the present invention, the hole blocking layer may be 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and / or tin oxide (SnO2).

[0043] In the present invention, the back electrode may be one or more selected from silver (Ag), copper (Cu) and gold (Au).

[0044] The present invention provides a method for preparing an inverted single-junction perovskite solar cell, which may include the following steps:

[0045] (1) depositing a hole transport layer on the surface of a transparent conductive substrate;

[0046] (2) depositing a perovskite film on the surface of the hole transport layer; that is, first coating the surface of the hole transport layer with a perovskite precursor solution, and then sequentially performing back annealing and front annealing;

[0047] (3) depositing an electron transport layer on the surface of the perovskite film;

[0048] (4) A back electrode is deposited on the surface of the electron transport layer to obtain an inverted single-junction perovskite solar cell.

[0049] In some embodiments, a method for preparing an inverted single-junction perovskite solar cell comprises the following steps:

[0050] (1) depositing a hole transport layer on the surface of a transparent conductive substrate;

[0051] (2) depositing a perovskite film on the surface of the hole transport layer; the deposition of the perovskite film includes first coating a perovskite precursor solution, then extracting with an anti-solvent, and finally sequentially performing back annealing and front annealing;

[0052] (3) depositing an electron transport layer on the surface of the perovskite film;

[0053] (4) depositing a hole blocking layer on the surface of the electron transport layer;

[0054] (5) A back electrode is deposited on the surface of the hole blocking layer to obtain an inverted single-junction perovskite solar cell.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (1) The present invention can adjust the annealing time to prevent nucleation and phase formation problems caused by too fast / too slow solvent evaporation, and effectively solve the problem of perovskite phase instability;

[0057] (2) The present invention can effectively improve and control the solvent evaporation rate; avoid the problem that DMSO evaporates too quickly or NMP remains too much during traditional front annealing, resulting in disordered grain size, low crystallinity, and many pinholes; and the problem that low-temperature annealing cannot be widely applied to anti-solvent-free systems;

[0058] (3) The present invention does not blindly add dopants, thus avoiding the introduction of other defects or band gap changes, and promoting it to maintain a band gap of 5.32-5.35 eV, which is beneficial to reducing the barrier to carrier transmission;

[0059] (4) The back-coating annealing method of the present invention can be generally applied to various heating instrument operations, and is convenient for the preparation of large-area perovskite solar cells and stacked perovskite solar cells, which is conducive to commercialization;

[0060] (5) The present invention utilizes the different solubility of solvents for PbBr2 or PbI2 to regulate the quality of the perovskite generated by the reaction and ensure high-quality device repeatability; for example, the solubility of PbBr2 in different solvents is different, and the solubility of PbBr2 in pure DMSO is slightly better than that in pure NMP. Therefore, when mixing DMSO:NMP, it is necessary to control the ratio of the solvents so that the solubility of PbBr2 is not affected and the device performance can be improved.

[0061] The present invention will be described below in the form of specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present invention. The methods, reagents and materials used in the examples are, unless otherwise stated, conventional methods, reagents and materials in the art. The raw material compounds in the examples can all be purchased through commercial routes.

[0062] Example 1

[0063] (1) placing the ITO substrate in an ultrasonic cleaning instrument, and ultrasonically cleaning it with deionized water, alcohol, deionized water, and alcohol respectively, each step lasting 15 minutes, and drying it with a N2 gun, and then UV-zone treating it for 20 minutes to obtain a clean transparent conductive substrate;

[0064] (2) preparing 0.5 mg / mL Me-4PACz solvent, spin coating it on the surface of a clean transparent conductive substrate at a spin coating speed of 4000 rpm for 30 s, and annealing at 100° C. for 7 min to obtain a hole transport layer with a thickness of 40 nm;

[0065] (3) 1.4 mmol of FAPbBr3 powder was dissolved in 1 mL of a mixed solvent of DMF and DMSO, wherein the volume ratio of DMF to DMSO was 4:1, and the mixture was stirred for 2 h at 70 °C to obtain a perovskite precursor solution; 100 μL of the perovskite precursor solution was spin-coated, and then annealed by combining back annealing and front annealing, that is, at a temperature of 130 °C, the film was first heated face down for 10 s, and then the film was heated face up at 150 °C for 20 min to obtain a perovskite film with a thickness of 650 nm;

[0066] (4) thermally evaporate 30 nm of C60 on the upper surface of the perovskite film as an electron transport layer;

[0067] (5) Thermally evaporate 5 nm of BCP on the electron transport layer as a hole blocking layer (the main function of BCP is to prevent electron-hole recombination);

[0068] (6) The effective area of ​​evaporation on the hole blocking layer is 0.071 cm 2 , silver with a thickness of 150nm is used as the back electrode, and a perovskite solar cell is obtained.

[0069] Example 2

[0070] The other conditions of this embodiment are the same as those of embodiment 1, except that the time for heating the film face downward is replaced from 10 s to 30 s in this embodiment.

[0071] Example 3

[0072] The other conditions of this embodiment are the same as those of embodiment 1, except that the time for heating the film face downward is replaced from 10 s to 60 s in this embodiment.

[0073] Example 4

[0074] The other conditions of this embodiment are the same as those of embodiment 1, except that the time for heating the film face downward is replaced from 10 s to 90 s in this embodiment.

[0075] Example 5

[0076] The other conditions of this embodiment are the same as those of embodiment 1, except that the time for heating the film face downward is replaced from 10 s to 120 s in this embodiment.

[0077] Example 6

[0078] The other conditions of this embodiment are the same as those of embodiment 1, except that the heating time of the film facing downward is replaced from 10 s to 200 s in this embodiment.

[0079] Example 7

[0080] The other conditions of this embodiment are the same as those of embodiment 1, except that the heating time of the film facing downward is replaced from 10 s to 300 s in this embodiment.

[0081] Example 8

[0082] The other conditions of this embodiment are the same as those of embodiment 1, except that the mixed solvent of this embodiment is DMF and NMP, and the volume ratio of DMF to NMP is 4:1.

[0083] Example 9

[0084] The other conditions of this embodiment are the same as those of Embodiment 8, except that the time for heating the film face downward is replaced from 10 s to 30 s in this embodiment.

[0085] Example 10

[0086] The other conditions of this embodiment are the same as those of Embodiment 8, except that the time for heating the film face downward is replaced from 10 s to 60 s in this embodiment.

[0087] Embodiment 11

[0088] The other conditions of this embodiment are the same as those of Embodiment 8, except that the time for heating the film face downward is replaced from 10 s to 90 s in this embodiment.

[0089] Example 12

[0090] The other conditions of this embodiment are the same as those of Embodiment 8, except that the time for heating the film face downward is replaced from 10 s to 120 s in this embodiment.

[0091] Example 13

[0092] The other conditions of this embodiment are the same as those of Embodiment 8, except that the heating time of the film facing downward is replaced from 10 s to 200 s in this embodiment.

[0093] Embodiment 14

[0094] The other conditions of this embodiment are the same as those of Embodiment 8, except that the heating time of the film facing downward is replaced from 10 s to 300 s in this embodiment.

[0095] Embodiment 15

[0096] The other conditions of this embodiment are the same as those of Embodiment 1, except that the mixed solvent of this embodiment is DMF, DMSO and NMP, and the volume ratio of DMF, DMSO and NMP is 3:1:1.

[0097] Example 16

[0098] The other conditions of this embodiment are the same as those of Embodiment 15, except that the time for heating the membrane face downward is replaced from 10 s to 30 s in this embodiment.

[0099] Embodiment 17

[0100] The other conditions of this embodiment are the same as those of Embodiment 15, except that the time for heating the membrane face downward is replaced from 10 s to 60 s in this embodiment.

[0101] Embodiment 18

[0102] The other conditions of this embodiment are the same as those of Embodiment 15, except that the time for heating the membrane face downward is replaced from 10 s to 90 s in this embodiment.

[0103] Embodiment 19

[0104] The other conditions of this embodiment are the same as those of Embodiment 15, except that the time for heating the membrane face downward is replaced from 10 s to 120 s in this embodiment.

[0105] Embodiment 20

[0106] The other conditions of this embodiment are the same as those of Embodiment 15, except that the time for heating the membrane face downward is replaced from 10 s to 200 s in this embodiment.

[0107] Embodiment 21

[0108] The other conditions of this embodiment are the same as those of Embodiment 15, except that the time for heating the membrane face downward is replaced from 10 s to 300 s in this embodiment.

[0109] Comparative Example 1

[0110] The other conditions of this comparative example are the same as those of Example 1, except that this comparative example does not perform back annealing, that is, this comparative example directly heats the film surface upward at a temperature of 150° C. for 20 minutes.

[0111] Comparative Example 2

[0112] The other conditions of this comparative example are the same as those of Example 8, except that this comparative example does not perform back annealing, that is, this comparative example directly heats the film surface upward at a temperature of 150° C. for 20 minutes.

[0113] Comparative Example 3

[0114] The other conditions of this comparative example are the same as those of Example 15, except that this comparative example does not perform back annealing, that is, this comparative example directly heats the film surface upward at a temperature of 150° C. for 20 minutes.

[0115] Comparative Example 4

[0116] The other conditions of this comparative example are the same as those of Example 1, except that this comparative example does not perform front annealing, and only heats the film surface downward at 130° C. for 20 min.

[0117] Comparative Example 5

[0118] The other conditions of this comparative example are the same as those of Example 8, except that this comparative example does not perform front annealing, and only heats the film surface downward at a temperature of 130° C. for 20 min.

[0119] Comparative Example 6

[0120] The other conditions of this comparative example are the same as those of Example 15, except that this comparative example does not perform front annealing, and only heats the film surface downward at 130° C. for 20 min.

[0121] Test Case

[0122] Photovoltaic performance test of perovskite solar cells: At 25°C and AM 1.5G standard solar spectrum, a solar simulator was used to set the voltage range to 1.1V to -0.1V. The current output of the perovskite solar cells prepared in Examples 1-21 and Comparative Examples 1-6 at different voltages was tested, and the corresponding current-voltage (IV) characteristic curves were plotted. The surface area of ​​the perovskite solar cell was 0.07068cm 2 , the incident light power (Pin) is 100mWcm -2 The open circuit voltage, short circuit current density, fill factor and photoelectric conversion efficiency of the perovskite solar cells prepared in Examples 1-21 and Comparative Examples 1-6 were obtained according to the characteristic curves.

[0123] (1) Open circuit voltage (Voc): The voltage value corresponding to when the current is equal to zero.

[0124] (2) Short-circuit current density (Jsc): The current value when the voltage is zero is the short-circuit current (Isc), and the current per unit battery surface area is the short-circuit current density.

[0125] (3) Fill factor (FF): The ratio of the maximum output power (Pmax) of the battery to the product of the open circuit voltage and the short circuit current. The calculation formula is (Pmax / Voc*Isc), where the maximum power point is the point where the battery output power reaches its maximum value.

[0126] (4) Photoelectric conversion efficiency (PCE): Photoelectric conversion efficiency refers to the ratio of maximum output power to incident light power (Pin), and the calculation formula is (Pmax / Pin)*100%.

[0127] The test results of the open circuit voltage, short circuit current density, fill factor and photoelectric conversion efficiency of the perovskite solar cells prepared in Examples 1-21 and Comparative Examples 1-6 are shown in Table 1.

[0128] Table 1: Open circuit voltage, short circuit current density, fill factor and photoelectric conversion efficiency of perovskite solar cells prepared in Examples 1-21 and Comparative Examples 1-6

[0129]

[0130]

Claims

1. A method for preparing a perovskite film, characterized in that: The preparation method comprises: firstly coating a perovskite precursor solution, and then sequentially performing back annealing and front annealing to obtain a perovskite film.

2. The preparation method according to claim 1, characterized in that: The perovskite precursor solution contains a perovskite structural substance and a solvent.

3. The preparation method according to claim 2, characterized in that: The preparation method has one or more of the following characteristics: The chemical formula of the perovskite structure material is ABX3, A is formamidinium ion and / or cesium ion; B is lead ion; X is bromide ion and / or iodide ion; In the perovskite precursor solution, the solvent is selected from one or more of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone and tetramethylene sulfoxide; In the perovskite precursor solution, the concentration of the perovskite structure substance is 1.4-2.0 mol / L.

4. The preparation method according to claim 1, characterized in that: The coating method is spin coating, blade coating or slit coating.

5. The preparation method according to claim 1, characterized in that: The back annealing temperature is 120-130°C; and / or The back annealing time is 10-300s.

6. The preparation method according to claim 1, characterized in that: The front annealing temperature is 130-150° C.; and / or The front annealing time is 15-20 minutes.

7. The preparation method according to claim 5, characterized in that: The back annealing time is 90-120s.

8. A perovskite film prepared by the preparation method according to any one of claims 1 to 7.

9. The perovskite film according to claim 8, characterized in that: The thickness of the perovskite film is 600-700 nm; and / or The perovskite film contains a perovskite structure material, the chemical formula of the perovskite structure material is ABX3, A is a formamidinium ion and / or a cesium ion; B is a lead ion; and X is a bromide ion and / or an iodine ion.

10. An inverse perovskite solar cell comprising the perovskite thin film according to claim 8 or 9.

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