Preparation method of perovskite thin film and preparation method of solar cell

Abstract

The invention provides a preparation method of a perovskite thin film and a preparation method of a solar cell. The preparation method comprises the following steps: forming a metal halide film on a substrate by adopting a thermal evaporation method, wherein the metal halide film at least comprises lead halide; an organic amine salt solution containing a mixed solvent is coated to the side, away from the substrate, of the metal halide thin film to form an organic amine salt thin film, and the mixed solvent comprises a proton polar solvent and an aprotic polar solvent; and performing heat treatment on the organic amine salt thin film and the metal halide thin film to form the perovskite thin film. According to the invention, the purposes of effectively promoting the full reaction of the organic phase and the inorganic phase and reducing the residual lead halide of the inorganic phase are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite solar cells, and in particular to a method for preparing a perovskite film, a method for preparing a solar cell, a solar cell and a solar cell module. Background Art

[0002] The process of preparing perovskite film in the prior art is generally divided into a one-step method and a two-step method. Among them, in the process of preparing perovskite film by the two-step method, the mixed evaporation-spin coating two-step method is a method that can conformally grow perovskite on velvet silicon, that is, firstly prepare the inorganic phase by thermal evaporation, and then spin coat the organic phase to prepare the perovskite layer. However, in the process of preparing the inorganic phase by thermal evaporation, the high density of the inorganic precursor layer hinders the penetration of the organic solution, so that the inorganic precursor cannot be completely converted into perovskite, resulting in a layer of unreacted PbI2 remaining on the velvet surface, which makes the performance, stability and repeatability of the device poor.

[0003] Moreover, in previous methods, the solvent of the organic phase solution used for spin coating is mostly a single solvent, isopropyl alcohol (IPA), so the problem of incomplete PbI2 reaction often occurs, and too much IPA will also dissolve the generated perovskite, resulting in a sharp drop in the efficiency and stability of the perovskite / crystalline silicon tandem solar cell.

[0004] Therefore, a new preparation process is urgently needed to effectively promote the complete reaction between inorganic precursors and organic phases. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for preparing a perovskite film, a method for preparing a solar cell, a solar cell and a solar cell module, so as to solve the problem in the prior art that in the process of forming a perovskite film, the inorganic precursor layer formed by the thermal evaporation method is highly dense, resulting in the inability to completely react between the inorganic precursor and the organic phase.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a method for preparing a perovskite film is provided, comprising: forming a metal halide film on a substrate by a thermal evaporation method, wherein the metal halide film comprises at least lead halide; applying an organic amine salt solution comprising a mixed solvent to a side of the metal halide film away from the substrate to form an organic amine salt film, wherein the mixed solvent comprises a protic polar solvent and a non-protic polar solvent; and heat-treating the organic amine salt film and the metal halide film to form the perovskite film.

[0007] Optionally, the aprotic polar solvent includes one or more of dimethylformamide, dimethyl sulfoxide, dimethylformamide, N-methyl-2-pyrrolidone and γ-butyrolactone.

[0008] Optionally, the protic polar solvent includes one or more of ethanol, methanol and isopropanol.

[0009] Optionally, the volume ratio of the aprotic polar solvent to the protic polar solvent is 0.5:99.5-10:90.

[0010] Optionally, the metal halide film further includes cesium halide.

[0011] Optionally, the organic amine salt solution is coated by a spin coating process.

[0012] According to another aspect of the present invention, a method for preparing a solar cell is provided, comprising: providing a stacked substrate and a perovskite film, wherein the perovskite film is prepared by the method for preparing the perovskite film as described above, and the substrate comprises at least a stacked transparent conductive layer and a hole transport layer, wherein the hole transport layer is located between the transparent conductive layer and the perovskite film; forming an electron transport layer on a side of the perovskite film away from the hole transport layer; and forming an electrode layer on a side of the electron transport layer away from the perovskite film.

[0013] Optionally, the substrate further comprises a crystalline silicon cell, and the crystalline silicon cell is located on a side of the transparent conductive layer away from the hole transport layer.

[0014] According to another aspect of the present invention, there is provided a solar cell, which is prepared by the above-mentioned method for preparing a solar cell.

[0015] According to yet another aspect of the present invention, a solar cell assembly is provided, comprising the solar cell as described above.

[0016] The technical scheme of the present invention is applied to provide a method for preparing a perovskite film, which comprises: firstly forming a metal halide film including at least lead halide on a substrate by a thermal evaporation method, and then, because the metal halide film with high density will hinder the organic amine salt solution from penetrating into the metal halide film, so that part of the lead halide in the metal halide film cannot complete the reaction with the organic amine salt solution, resulting in part of the lead halide remaining in the finally formed perovskite film, so that the film quality of the perovskite film is poor, and the performance, stability and repeatability of the device having the perovskite film are poor. Therefore, after the above-mentioned metal halide film including at least lead halide is formed by a thermal evaporation method, the organic amine salt solution including a mixed solvent can be coated on the surface of one side of the metal halide film away from the substrate to form an organic amine salt layer, and the above-mentioned mixed solvent includes a protic polar solvent and a non-protic polar solvent, and finally, the organic amine salt film and the metal halide film are heat-treated to form a perovskite film. That is, the present application adds a protonic polar solvent and a non-protonic polar solvent with a high coordination number that can coordinate with lead halide to an organic amine salt solution, so that after the organic amine salt solution is coated on the metal halide film, part of the inorganic phase in the metal halide film is dissolved, thereby reducing the high density of the metal halide film formed by thermal evaporation, allowing the organic phase to further penetrate the metal halide film, thereby achieving the purpose of effectively promoting the full reaction of the organic phase and the inorganic phase and reducing the residual lead halide in the inorganic phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0018] Figure 1 A schematic cross-sectional structure diagram of a solar cell according to an embodiment of the present invention is shown.

[0019] The above drawings include the following reference numerals:

[0020] 10. Crystalline silicon cell; 20. Transparent conductive layer; 30. Hole transport layer; 40. Perovskite film; 50. Electron transport layer; 60. Buffer layer; 70. Transparent conductive layer; 80. Metal layer. DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0022] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0023] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present invention described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0024] As described in the background art, the process for preparing perovskite thin films in the prior art is generally divided into a one-step method and a two-step method. Among them, in the process of preparing perovskite thin films by the two-step method, the mixed evaporation-spin coating two-step method is a method that can conformally grow perovskite on velvet silicon, that is, firstly prepare the inorganic phase by thermal evaporation, and then spin-coat the organic phase to prepare the perovskite layer. However, in the process of preparing the inorganic phase by thermal evaporation, the high density of the inorganic precursor layer hinders the penetration of the organic solution, so that the inorganic precursor cannot be completely converted into perovskite, resulting in a layer of unreacted PbI2 remaining on the velvet surface, making the performance, stability and repeatability of the device poor. In addition, in the previous method, the solvent of the organic phase solution used for spin coating is mostly a single solvent isopropyl alcohol (IPA), so the problem of incomplete reaction of PbI2 often occurs, and too much IPA will also dissolve the generated perovskite, resulting in a sharp decrease in the efficiency and stability of the perovskite / crystalline silicon laminated solar cell. Therefore, a new preparation process is urgently needed to effectively promote the complete reaction of the inorganic precursor and the organic phase. In summary, in order to solve the problem in the prior art that in the process of forming perovskite film, the inorganic precursor layer formed by thermal evaporation is highly dense, resulting in the inability to completely react between the inorganic precursor and the organic phase, the present application provides a method for preparing a perovskite film, a method for preparing a solar cell, a solar cell and a solar cell module.

[0025] According to one aspect of the present application, a method for preparing a perovskite film is provided, the preparation method comprising: forming a metal halide film on a substrate by a thermal evaporation method, wherein the metal halide film comprises at least lead halide; applying an organic amine salt solution comprising a mixed solvent to a side of the metal halide film away from the substrate to form an organic amine salt film, wherein the mixed solvent comprises a protic polar solvent and a non-protic polar solvent; and heat-treating the organic amine salt film and the metal halide film to form the perovskite film.

[0026] Specifically, in the above embodiment, the substrate may include a transparent conductive layer, and the material of the transparent conductive layer may be any one of indium tin oxide (ITO), zinc oxide (ZnO), indium zinc oxide (IZO) and aluminum zinc oxide (AZO).

[0027] Specifically, in the step of forming the metal halide film by thermal evaporation, the evaporation source may include at least lead halide, so that the formed metal halide film includes at least lead halide. Exemplarily, the metal halide film may include but is not limited to one or more of lead iodide (PbI2), lead bromide (PbBr2) and lead chloride (PbCl2).

[0028] Specifically, an organic amine salt solution including a mixed solvent is first prepared, so that the organic amine salt solution can include a protic polar solvent, an aprotic polar solvent and an organic amine salt. Then, the organic amine salt solution can be coated on the side of the metal halide film away from the substrate to form an organic amine salt film. In the step of coating the organic amine salt solution, the coating process used can include but is not limited to any one of spin coating, scraper coating and spray coating.

[0029] Specifically, in the step of heat treating the organic amine salt film and the metal halide film, the heat treatment step may be an annealing process to improve the quality and performance of the perovskite film.

[0030] In the above embodiment, a method for preparing a perovskite film is provided, the method comprising: firstly forming a metal halide film including at least lead halide on a substrate by a thermal evaporation method, and then, because the metal halide film with high density will hinder the organic amine salt solution from penetrating into the metal halide film, part of the lead halide in the metal halide film cannot react with the organic amine salt solution, resulting in part of the lead halide remaining in the finally formed perovskite film, making the film quality of the perovskite film poor, and making the performance, stability and repeatability of the device having the perovskite film poor. Therefore, after the above metal halide film including at least lead halide is formed by a thermal evaporation method, the organic amine salt solution including a mixed solvent can be coated on the surface of the side of the metal halide film away from the substrate to form an organic amine salt layer, and the above mixed solvent includes a protic polar solvent and a non-protic polar solvent, and finally, the organic amine salt film and the metal halide film are heat treated to form a perovskite film. That is, the present application adds a protonic polar solvent and a non-protonic polar solvent with a high coordination number that can coordinate with lead halide to an organic amine salt solution, so that after the organic amine salt solution is coated on the metal halide film, part of the inorganic phase in the metal halide film is dissolved, thereby reducing the high density of the metal halide film formed by thermal evaporation, allowing the organic phase to further penetrate the metal halide film, thereby achieving the purpose of effectively promoting the full reaction of the organic phase and the inorganic phase and reducing the residual lead halide in the inorganic phase.

[0031] In order to make the organic phase in the organic amine salt solution fully react with the inorganic phase in the metal halide film, this embodiment provides a mixed solvent that can change the polarity of the organic phase solvent in the organic amine salt solution, that is, a mixed solvent of a protic polar solvent and an aprotic polar solvent. Among them, dimethylformamide, dimethyl sulfoxide, dimethylformamide, N-methyl-2-pyrrolidone and γ-butyrolactone can all be used to change the polarity of the organic phase solvent and the solubility of the solvent. Therefore, in some optional embodiments, the above-mentioned aprotic polar solvent can include one or more of dimethylformamide, dimethyl sulfoxide, dimethylformamide, N-methyl-2-pyrrolidone and γ-butyrolactone.

[0032] Similarly, ethanol, methanol and isopropanol can also change the polarity of the organic phase solvent in the organic amine salt solution and the solubility of the solvent. Therefore, in order to further adjust the polarity of the organic phase solvent in the organic amine salt solution, in some optional embodiments, the above-mentioned protonic polar solvent may include one or more of ethanol, methanol and isopropanol.

[0033] Illustratively, the mixed solvent may be formed by a combination of one or more of dimethylformamide, dimethyl sulfoxide, dimethylformamide, N-methyl-2-pyrrolidone and γ-butyrolactone and one or more of ethanol, methanol and isopropanol.

[0034] In order to allow the organic amine salt solution including the above-mentioned mixed solvent to fully react with the metal halide film and improve the film quality of the perovskite film in the prior art, in some optional embodiments, the volume ratio of the above-mentioned non-protonic polar solvent to the above-mentioned protonic polar solvent is 0.5:99.5~10:90.

[0035] Exemplarily, the protic polar solvent may be isopropyl alcohol (IPA), and the aprotic polar solvent may be one or more of the dimethylformamide, dimethyl sulfoxide, dimethylformamide, N-methyl-2-pyrrolidone and γ-butyrolactone. The volume of the isopropyl alcohol solvent may be regarded as the first volume, and the volume of one or more of the dimethylformamide, dimethyl sulfoxide, dimethylformamide, N-methyl-2-pyrrolidone and γ-butyrolactone may be regarded as the second volume. Then, the ratio of the first volume to the second volume is between 0.5:99.5 and 10:90.

[0036] In order to achieve at least one of the following purposes: improving the stability of the perovskite film, expanding the spectral response range of the perovskite film, and improving the photoelectric conversion efficiency of the solar cell when the perovskite film is applied to the solar cell, in some optional embodiments, the metal halide film also includes cesium halide.

[0037] Specifically, the metal halide film may include but is not limited to one or more of cesium iodide (CsI2), cesium bromide (CsBr2) and cesium chloride (CsCl2).

[0038] That is, in the above-mentioned embodiment, in the process of forming the above-mentioned metal halide film by thermal evaporation, the evaporation source may include the above-mentioned lead halide and cesium halide. Specifically, the above-mentioned evaporation source may be formed by a combination of one or more of lead iodide (PbI2), lead bromide (PbBr2) and lead chloride (PbCl2) and one or more of cesium iodide (CsI2), cesium bromide (CsBr2) and cesium chloride (CsCl2).

[0039] In some optional embodiments, since the use of a spin coating process to prepare a thin film has the beneficial effects of achieving precise control of film thickness, reducing preparation costs, improving preparation efficiency, and wide applicability, the spin coating process is used in this embodiment to coat the above-mentioned organic amine salt solution.

[0040] According to another aspect of the present application, a perovskite film is provided, and the perovskite film can be prepared by using the above-mentioned method for preparing the perovskite film.

[0041] In summary, in the above-mentioned embodiment, since the perovskite film is formed by a thermal evaporation method and a coating process, and during the formation process, since a proton polar solvent and a non-protonic polar solvent with a high coordination number that can coordinate with lead halide are added to the organic amine salt solution, after the organic amine salt solution is coated on the metal halide film, part of the inorganic phase in the metal halide film can be dissolved, thereby reducing the high density of the metal halide film formed by the thermal evaporation method, allowing the organic phase to further penetrate the metal halide film, thereby effectively promoting the full reaction of the inorganic phase and the organic phase, and reducing the residual lead halide in the inorganic phase. Therefore, the perovskite film in this embodiment is more stable than the perovskite film in the prior art and has a wider spectral response range.

[0042] According to another aspect of the present application, a method for preparing a solar cell is provided, and the preparation method may include: providing a stacked substrate and a perovskite film, the perovskite film being prepared by the above-mentioned method for preparing the perovskite film, and the substrate at least includes a stacked transparent conductive layer and a hole transport layer, the hole transport layer being located between the transparent conductive layer and the perovskite film; forming an electron transport layer on a side of the perovskite film away from the hole transport layer; and forming an electrode layer on a side of the electron transport layer away from the perovskite film.

[0043] In the above embodiment, before the step of providing a substrate, the above preparation method may further include: providing a transparent conductive layer, and forming a hole transport layer on one side of the transparent conductive layer. The material of the above transparent conductive layer may include but is not limited to any one of indium tin oxide (ITO), fluorine tin oxide (FTO), indium zinc oxide (IZO) and aluminum zinc oxide (AZO). The above hole transport layer may include but is not limited to poly[di(4-anilinophenyl)ethylene] (PTAA), poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) salt (PEDOT:PSS) and nickel oxide (NiO x )

[0044] Specifically, a hole transport layer may be formed on one side of the transparent conductive layer by spin coating or evaporation.

[0045] Specifically, a metal halide film can be first formed on the side of the hole transport layer away from the transparent conductive layer by a thermal evaporation method, wherein the metal halide film includes at least lead halide, and then an organic amine salt solution including a mixed solvent is applied to the side of the metal halide film away from the substrate to form an organic amine salt film, wherein the mixed reagent includes a protic polar solvent and an aprotic polar solvent, and then the organic amine salt film and the metal halide film can be heat-treated to finally form the above-mentioned perovskite film on the side of the hole transport layer away from the transparent conductive layer. Exemplarily, the thickness of the above-mentioned perovskite film can be 300 to 500 nm.

[0046] Specifically, in the step of forming the metal halide film by thermal evaporation, the evaporation rate can be

[0047]

[0048] Specifically, an electron transport layer can be formed on the side of the perovskite film away from the hole transport layer by evaporation or spin coating. And exemplarily, the material of the electron transport layer may include titanium oxide (TiO2), fullerene derivatives (PCBM) and C 60 One or more of the above.

[0049] Specifically, a sputtering method can be used to form an electrode layer on the side of the electron transport layer away from the perovskite film. In addition, the material of the electrode layer may include any one or more of a transparent conductive material and a metal material. Exemplarily, the electrode layer may include a transparent conductive layer and a metal layer, and the transparent conductive layer is located between the electron transport layer and the metal layer. Among them, the material of the above-mentioned transparent conductive layer may include but is not limited to any one of indium tin oxide (ITO), fluorine tin oxide (FTO), indium zinc oxide (IZO) and aluminum zinc oxide (AZO), and the material of the metal layer may include but is not limited to any one of gold (Au), silver (Ag), copper (Cu) and aluminum (Al). Furthermore, the above-mentioned transparent conductive layer can be formed by a sputtering method, and the above-mentioned electrode layer can be formed by any one of screen printing, thermal evaporation and magnetron sputtering.

[0050] In order to improve electron mobility and reduce the damage to the substrate during the process of forming the electrode layer, in some optional embodiments, before the step of forming the electrode layer, the method for preparing a solar cell further includes: forming a buffer layer on the side of the electron transport layer away from the perovskite film. Exemplarily, the buffer layer can be formed by an atomic layer deposition process, and the material of the buffer layer can be tin dioxide.

[0051] In some optional embodiments, in order to broaden the spectral range of the perovskite solar cell, the substrate further comprises a crystalline silicon cell, and the crystalline silicon cell is located on the side of the transparent conductive layer away from the hole transport layer. Exemplarily, the crystalline silicon cell may include but is not limited to any one of a rear passivation cell (PERC), a tunneling oxide passivation cell (TOPCon), a heterojunction cell (HJT), an N-type all-back electrode contact cell (N-IBC), and a P-type all-back electrode contact cell (P-IBC).

[0052] According to another aspect of the present application, a solar cell is provided, which is prepared by the above-mentioned method for preparing a solar cell. Figure 1 As shown, the solar cell may include a stacked crystalline silicon cell 10 , a transparent conductive layer 20 , a hole transport layer 30 , a perovskite film 40 , an electron transport layer 50 , a buffer layer 60 , a transparent conductive layer 70 and a metal layer 80 .

[0053] According to another aspect of the present application, a solar cell assembly is provided, comprising the solar cell as described above.

[0054] The solar cell prepared by the method for preparing a solar cell of the present application will be further described below with reference to examples.

[0055] Example 1

[0056] A semiconductor substrate is provided, wherein the semiconductor substrate comprises a stacked crystalline silicon cell, a transparent conductive layer and a hole transport layer. The crystalline silicon cell may be a passivated emitter rear cell (PERC), the transparent conductive layer may be indium tin oxide (ITO), and the hole transport layer may be a poly[bis(4-anilinophenyl)ethylene] (PTAA) layer;

[0057] A lead iodide film is formed on the side of the hole transport layer away from the crystalline silicon cell by thermal evaporation. The evaporation rate of the thermal evaporation method is Then, an organic amine salt solution including a mixed solvent is spin-coated on a side of the lead iodide film away from the hole transport layer, wherein the mixed solvent includes isopropyl alcohol and dimethylformamide, and the volume ratio of dimethylformamide to isopropyl alcohol is 1:20; and then, after an annealing process, a perovskite film is formed;

[0058] An electron transport layer is formed on a side of the perovskite film away from the hole transport layer by using an evaporation process, wherein the electron transport layer is a titanium oxide (TiO2) layer;

[0059] A buffer layer is formed on the side of the electron transport layer away from the perovskite film by using an atomic layer deposition process, and the buffer layer is a tin dioxide layer;

[0060] A sputtering process is used to form a transparent conductive layer on a side of the buffer layer away from the electron transport layer, wherein the transparent conductive layer is an indium tin oxide (ITO) layer;

[0061] A metal layer is formed on a side of the transparent conductive layer away from the buffer layer by using a screen printing process. The metal layer is a silver (Ag) layer.

[0062] Example 2

[0063] Different from Example 1, the volume ratio of dimethylformamide to isopropanol in this example is 0.5:99.5.

[0064] Example 3

[0065] Different from Example 1, the volume ratio of dimethylformamide to isopropanol in this example is 10:90.

[0066] Example 4

[0067] Different from Example 1, in this example, dimethylformamide was not added to the solvent when preparing the perovskite film.

[0068] The photoelectric performance test of the device obtained in the above embodiment was carried out, and then the photoelectric performance test parameters shown in Table 1 were obtained:

[0069] Table 1

[0070] Example 1 Example 2 Example 3 Example 4 Conversion efficiency 24.450％ 24.235％ 24.520％ 24.032％

[0071] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0072] After a metal halide film including at least lead halide is first formed on a substrate by thermal evaporation, the metal halide film with high density will hinder the organic amine salt solution from penetrating into the metal halide film, so that part of the lead halide in the metal halide film cannot complete the reaction with the organic amine salt solution, resulting in part of the lead halide remaining in the finally formed perovskite film, making the film quality of the perovskite film poor, and making the performance, stability and repeatability of the device with the perovskite film poor. Therefore, in a method for preparing a perovskite film provided in the present application, after the above-mentioned metal halide film including at least lead halide is formed by thermal evaporation, an organic amine salt solution including a mixed solvent can be coated on the surface of one side of the metal halide film away from the substrate to form an organic amine salt layer, and the above-mentioned mixed solvent includes a protic polar solvent and a non-protic polar solvent, and finally, the organic amine salt film and the metal halide film are heat-treated to form a perovskite film. That is, the present application adds a protonic polar solvent and a non-protonic polar solvent with a high coordination number that can coordinate with lead halide to an organic amine salt solution, so that after the organic amine salt solution is coated on the metal halide film, part of the inorganic phase in the metal halide film is dissolved, thereby reducing the high density of the metal halide film formed by thermal evaporation, allowing the organic phase to further penetrate the metal halide film, thereby effectively promoting the full reaction of the inorganic phase and the organic phase, reducing the residual lead halide in the inorganic phase, and improving the battery conversion efficiency.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a perovskite film, characterized in that: include: Forming a metal halide film on a substrate by a thermal evaporation method, wherein the metal halide film comprises at least lead halide; Applying an organic amine salt solution including a mixed solvent to a side of the metal halide film away from the substrate to form an organic amine salt film, wherein the mixed solvent includes a protic polar solvent and a non-protic polar solvent; The organic amine salt film and the metal halide film are heat-treated to form the perovskite film.

2. The preparation method according to claim 1, characterized in that: The aprotic polar solvent includes one or more of dimethylformamide, dimethyl sulfoxide, dimethylformamide, N-methyl-2-pyrrolidone and γ-butyrolactone.

3. The preparation method according to claim 1, characterized in that: The protic polar solvent includes one or more of ethanol, methanol and isopropanol.

4. The preparation method according to any one of claims 1 to 3, characterized in that The volume ratio of the aprotic polar solvent to the protic polar solvent is 0.5:99.5 to 10:

90.

5. The preparation method according to any one of claims 1 to 3, characterized in that: The metal halide film also includes cesium halide.

6. The preparation method according to any one of claims 1 to 3, characterized in that: The organic amine salt solution is coated by a spin coating process.

7. A method for preparing a solar cell, characterized in that: include: Providing a stacked substrate and a perovskite film, wherein the perovskite film is prepared by the method for preparing a perovskite film according to any one of claims 1 to 6, and the substrate at least comprises a stacked transparent conductive layer and a hole transport layer, wherein the hole transport layer is located between the transparent conductive layer and the perovskite film; forming an electron transport layer on a side of the perovskite film away from the hole transport layer; An electrode layer is formed on a side of the electron transport layer away from the perovskite film.

8. The preparation method according to claim 7, characterized in that: The substrate further comprises a crystalline silicon cell, and the crystalline silicon cell is located on a side of the transparent conductive layer away from the hole transport layer.

9. A solar cell, characterized in that: The solar cell is prepared by the method for preparing the solar cell as claimed in claim 7 or 8.

10. A solar cell module, characterized in that: Comprising the solar cell as claimed in claim 9.

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