Deep defect passivated perovskite thin film, preparation method thereof and perovskite solar cell

Abstract

The invention provides a deep defect passivated perovskite thin film and a preparation method thereof, and a perovskite solar cell. The preparation method comprises the following steps: preparing a passivation solution by using defect passivation molecules; mixing the passivation solution and a perovskite precursor solution according to a set proportion to prepare a first perovskite thin film; or coating the passivation solution on at least one surface of a perovskite base film formed by a perovskite precursor solution to form a passivation layer; performing heat treatment on the passivation layer and the perovskite base film to obtain a second perovskite thin film; the defect passivation molecules inhibit generation of halide anions and organic cations in the first perovskite thin film or the second perovskite thin film. According to the invention, the defect passivation molecules and the perovskite base film or the perovskite precursor solution are utilized to form a low-dimensional deep-layer defect passivation perovskite thin film structure, so that the energy level matching deep-layer defect passivation perovskite thin film is optimized.

Description

Technical Field

[0001] This application relates to the technical field of perovskite solar cell preparation, and particularly to perovskite thin films with deep defect passivation, their preparation methods, and perovskite solar cells. Background Art

[0002] Perovskite solar cells have attracted much attention in recent years due to their potential for high efficiency and low cost. However, defects such as grain boundary defects, surface defects, and bulk defects are likely to occur during the preparation of perovskite thin films. These defects will lead to an increase in the charge recombination rate, thereby reducing the cell efficiency and accelerating its aging. Therefore, how to effectively passivate these defects to improve the device performance and stability has become the focus of research. In the prior art, chemical passivators or surface treatment methods are usually used to repair the defects of perovskite thin films, but the passivation effect of these methods is not durable enough and may introduce new interface problems. Therefore, there is still a need to develop more effective passivation strategies to further improve the performance of perovskite solar cells. Summary of the Invention

[0003] This application aims to solve at least one of the technical problems in the related art to some extent. This application proposes a perovskite thin film with deep defect passivation, its preparation method, and a perovskite solar cell. This application uses a defect passivation molecule to form a low-dimensional perovskite thin film structure with deep defect passivation with a perovskite base film or a perovskite precursor solution, thereby optimizing the energy level matching and enhancing the water and oxygen erosion resistance of the perovskite thin film with deep defect passivation. In addition, the defect passivation molecule is a nitrogen-containing hybrid derivative, which can interact with lead ions in the perovskite thin film. Specifically, the fluorine atoms on the nitrogen-containing hybrid derivative can have strong interactions with lead ions and organic cations in the surrounding perovskite base film or perovskite precursor solution, thereby inhibiting the formation of halide anions and organic cations in the formed perovskite thin film.

[0004] To achieve the above object, according to the first aspect of this application, a preparation method of a perovskite thin film with deep defect passivation is proposed, including the following steps:

[0005] Prepare a passivation solution using a defect passivation molecule;

[0006] Mix the passivation solution and the perovskite precursor solution according to a set ratio to prepare a first perovskite thin film; or

[0007] Coat the passivation solution on at least one surface of a perovskite base film formed by a perovskite precursor solution to form a passivation layer; after heat-treating the passivation layer and the perovskite base film, obtain a second perovskite thin film;

[0008] The defect passivation molecule inhibits the formation of halide anions and organic cations in the first perovskite thin film or the second perovskite thin film.

[0009] In some embodiments, the passivation solution is obtained by dissolving defect passivation molecules in a solvent, and the addition ratio of the defect passivation molecules to the perovskite precursor solution during the preparation of the first perovskite film is 1 mg / ml - 10 mg / ml;

[0010] and / or; when preparing the second perovskite film, the addition ratio of the defect passivation molecules to the solvent is 0.1 mg / ml - 5 mg / ml;

[0011] and / or; the solvent is at least one of isopropyl alcohol, trifluoroethanol, and hexafluoroisopropanol;

[0012] and / or; the defect passivation molecule is a nitrogen-containing hybrid derivative, and its structural formula is

[0013] In some embodiments, the preparation method of the perovskite precursor solution is: dissolving lead iodide, lead bromide, formamidinium iodide, and cesium iodide with a molar ratio of 0.85:0.15:0.78:0.22 in a mixed solution composed of DMF and DMSO with a volume ratio of 4:1.

[0014] In some embodiments, during the preparation of the first perovskite film, the passivation solution is added to the perovskite precursor solution, and a perovskite wet film with a thickness of 50 μm - 300 μm is prepared, and then annealed at 100 °C for 20 - 30 min to obtain the first perovskite film.

[0015] In some embodiments, during the preparation of the second perovskite film, the passivation layer is formed by coating or spin coating.

[0016] In some embodiments, the heat treatment parameters of the passivation layer are 80 °C - 120 °C, lasting for 5 - 30 min.

[0017] In some embodiments, the thickness of the passivation layer is 2 nm - 10 nm.

[0018] According to the second aspect of the present application, a perovskite film is provided, which is prepared by using the preparation method described in any of the above embodiments, and includes a first perovskite film or a second perovskite film.

[0019] According to the third aspect of the present application, a perovskite solar cell is provided, which includes the first perovskite film or the second perovskite film described in any of the above embodiments.

[0020] In some embodiments, the perovskite solar cell further includes a substrate, a semiconductor material layer, a hole transport layer, a charge transport layer, and a metal layer; wherein, the first perovskite thin film or the second perovskite thin film is located between the hole transport layer and the charge transport layer.

[0021] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. Description of the Drawings

[0022] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description of the embodiments in conjunction with the drawings, where:

[0023] Figure 1 is a schematic structural diagram of a first perovskite thin film in an embodiment of the present application;

[0024] Figure 2 is a schematic structural diagram of a second perovskite thin film in an embodiment of the present application;

[0025] Figure 3 is the current-voltage curve diagram of the battery of Example 1 and Comparative Example 1 of the present application and their corresponding aged ones. Detailed Description of the Embodiments

[0026] The embodiments of the present application will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present application and should not be construed as a limitation of the present application. On the contrary, the embodiments of the present application include all changes, modifications, and equivalents falling within the spirit and connotation of the appended claims.

[0027] The present application is improved based on the following related technologies: Perovskite solar cells have attracted much attention in recent years due to their potential for high efficiency and low cost. However, perovskite thin films are prone to defects during the preparation process, such as grain boundary defects, surface defects, and bulk defects, etc. These defects will lead to an increase in the charge recombination rate, thereby reducing the battery efficiency and accelerating its aging. Therefore, how to effectively passivate these defects to improve the device performance and stability has become the focus of research. In the prior art, chemical passivators or surface treatment methods are usually used to repair the defects of perovskite thin films, but the passivation effect of these methods is not durable enough and may introduce new interface problems. Therefore, there is still a need to develop more effective passivation strategies to further improve the performance of perovskite cells.

[0028] This application aims to solve at least one of the technical problems in the related art to some extent. To achieve the above object, according to the first aspect of this application, a method for preparing a perovskite thin film with deep defect passivation is provided, including the following steps:

[0029] S1: Prepare a passivation solution using a defect passivation molecule;

[0030] S2: Mix the passivation solution and the perovskite precursor solution in a set ratio to prepare a first perovskite thin film; or

[0031] Coat the passivation solution on at least one surface of the perovskite-based film formed by the perovskite precursor solution to form a passivation layer; after heat-treating the passivation layer and the perovskite-based film, a second perovskite thin film is obtained;

[0032] The defect passivation molecule inhibits the generation of halide anions and organic cations in the first perovskite thin film or the second perovskite thin film.

[0033] Among them, in S1, a defect passivation molecule is used to prepare a passivation solution. The passivation solution is obtained by dissolving the defect passivation molecule in a solvent. The defect passivation molecule is a nitrogen-containing hybrid derivative, and one of its structural formulas is The solvent is at least one of isopropyl alcohol, trifluoroethanol, and hexafluoroisopropanol. According to the differences in the preparation of the first perovskite thin film and the second perovskite thin film, the defect passivation molecule has different addition standards. The preparation method of the perovskite precursor solution is as follows: Lead iodide, lead bromide, formamidinium iodide, and cesium iodide with a molar ratio of 0.85:0.15:0.78:0.22 are dissolved in a mixed solution composed of DMF and DMSO with a volume ratio of 4:1 to obtain.

[0034] Among them, in S2, in the preparation process of the exemplary first perovskite thin film, a one-step method is adopted, that is, the passivation solution is added to the perovskite precursor solution, and the mixed solution of the passivation solution and the perovskite precursor solution is spin-coated on a substrate to form a film. After passivating for a set time, ethyl acetate antisolvent is added dropwise, and then annealed at 100 °C for 20 min, and then annealed to form the first perovskite thin film.

[0035] Add the passivation solution to the perovskite precursor solution. In the preparation process of the first perovskite thin film, the addition ratio of the defect passivation molecule to the perovskite precursor solution is 1 mg / ml - 10 mg / ml; use the mixed solution of the defect passivation molecule and the perovskite precursor solution to prepare a perovskite wet film with a thickness of 50 μm - 300 μm, and anneal at 100 °C for 20 - 30 min to obtain the first perovskite thin film.

[0036] The addition ratio of the defect passivation molecule to the perovskite precursor solution is 1 mg / ml - 10 mg / ml. The addition ratios of the exemplary defect passivation molecule to the perovskite precursor solution are 1 mg / ml, 2 mg / ml, 3 mg / ml, 5 mg / ml, 6 mg / ml, 7 mg / ml, 9 mg / ml, 10 mg / ml, etc. If the addition ratio of the defect passivation molecule is too large, such as greater than 10 mg / ml, the resistance of the first perovskite film increases, hindering the carrier transport; conversely, if the addition ratio of the defect passivation molecule is too small, such as less than 1 mg / ml, the defect passivation effect is not obvious and the passivation effect is poor.

[0037] Using the perovskite solution obtained by mixing the above-mentioned defect passivation molecule and the perovskite precursor solution, a perovskite wet film with a thickness of 50 μm - 300 μm is prepared by spin coating / spraying / blade coating, etc., and then annealed at 100 °C for 20 - 30 min to obtain the first perovskite film. Among them, spin coating / spraying / blade coating and other methods can all adopt the conventional technical methods in the field and will not be elaborated.

[0038] In S2, in some embodiments, the preparation process of the second perovskite film is as follows: Prepare a perovskite precursor solution, and the preparation method of the perovskite precursor solution refers to the above content and will not be elaborated. Use the perovskite precursor solution to prepare a perovskite wet film with a set thickness by spin coating / spraying / blade coating, etc., and add ethyl acetate antisolvent after forming the perovskite wet film for 30 s, and then anneal at 100 °C for 20 - 30 min to obtain a perovskite base film. The passivation solution in any of the above embodiments is formed by coating or blade coating to form a passivation layer on one surface of the perovskite base film, and then the heat treatment parameters of the passivation layer are 80 °C - 120 °C for 5 - 30 min to obtain a passivation layer with a thickness of 2 nm - 10 nm.

[0039] According to the second aspect of the present application, a perovskite film is proposed, which is prepared by using the preparation method in any of the above embodiments, and includes the first perovskite film or the second perovskite film.

[0040] According to the third aspect of the present application, a perovskite solar cell is proposed, which includes the first perovskite film or the second perovskite film in any of the above embodiments.

[0041] In some embodiments, the perovskite solar cell further includes a substrate, a semiconductor material layer, a hole transport layer, a charge transport layer, and a metal layer; wherein, the first perovskite film or the second perovskite film is located between the hole transport layer and the charge transport layer.

[0042] The substrate can be a commercially available ITO thin film (including a glass plate), the semiconductor material layer can be nickel oxide (with a thickness of 20 nm and x ≤ 1), the hole transport layer can be a BCP hole blocking layer, the charge transport layer is a C60 electron transport layer, and the metal layer is an Au, Cu electrode, etc.

[0043] Among them, the first perovskite thin film is located between the hole transport layer and the charge transport layer as Figure 1 shown, the second perovskite thin film is located between the hole transport layer and the charge transport layer, and the passivation layer in the second perovskite thin film faces the charge transport layer and / or the hole transport layer as Figure 2 shown.

[0044] To facilitate a further understanding of the present application, the solutions of the present application will be further described below in conjunction with embodiments. Those skilled in the art will understand that only some embodiments are described in the present application, and any other suitable specific embodiments are within the scope of the present application.

[0045] Embodiment 1

[0046] This embodiment provides a second perovskite thin film and applies it to a perovskite solar cell. Its specific composition and preparation method are as follows: Clean the glass, and sputter a 150-nm ITO thin film on the glass by magnetron sputtering; spin-coat an aqueous solution of nickel oxide nanoparticles on the surface of the ITO thin film glass at 10 mg / ml, 3000 revolutions per minute, and heat it on a hot stage at 100 °C for 10 min to obtain a dense nickel oxide thin film with a thickness of 15 nm. Dissolve lead iodide, lead bromide, formamidinium iodide, and cesium iodide with a molar ratio of 0.85:0.15:0.78:0.22 in a mixed solution composed of DMF and DMSO with a volume ratio of 4:1 to obtain a perovskite precursor solution; take 200 μL of the perovskite precursor solution and evenly spread it on the side to be spin-coated with nickel oxide, and spin-coat it into a perovskite wet film at 4000 rpm for 40 s at room temperature of 25 °C. Add 300 μl of ethyl acetate antisolvent at the 30th second, and then anneal it at 100 °C for 20 min to obtain a 600-nm perovskite base film.

[0047] Dissolve defect passivation molecules containing multiple active sites in isopropyl alcohol, and the addition ratio of the defect passivation molecules to isopropyl alcohol is 0.5 mg / ml to obtain a passivation solution. Spread the passivation solution evenly on one end of the surface of the prepared perovskite base film, spin-coat it at 4000 rpm for 20 s to form a film, and then anneal it at 100 °C for 20 min to obtain a passivation layer to complete the preparation of the second perovskite thin film.

[0048] Evaporate a layer of C60 electron transport layer (30 nm) and a BCP hole blocking layer on the surface of the passivation layer prepared above to obtain a perovskite solar cell. Transfer the electron transport layer to a thermal evaporation device, and the vacuum degree reaches 1×10 -5Under the condition of 1 Pa, the copper electrode (Cu) was evaporated with a thickness of 100 nm to obtain a perovskite solar cell.

[0049] Example 2

[0050] This example provides a first perovskite thin film and applies it to a perovskite solar cell. Its specific composition and preparation method are as follows:

[0051] The glass was cleaned, and a 150-nm ITO thin film was sputtered on the glass by magnetron sputtering. An aqueous solution of nickel oxide nanoparticles with a concentration of 10 mg / ml was spin-coated on the surface of the ITO thin film glass at 3000 revolutions per minute and heated on a hot plate at 100 °C for 10 min to obtain a dense nickel oxide thin film with a thickness of 15 nm. Lead iodide, lead bromide, formamidinium iodide, and cesium iodide with a molar ratio of 0.85:0.15:0.78:0.22 were dissolved in a mixed solution composed of DMF and DMSO with a volume ratio of 4:1 to obtain a perovskite precursor solution.

[0052] A defect passivation molecule containing multiple active sites was dissolved in isopropanol, and the addition ratio of the defect passivation molecule to isopropanol was 0.1 mg / ml to obtain a passivation solution. After mixing the passivation solution and the perovskite precursor solution at an addition ratio of 0.1 mg / ml, it was spin-coated into a film at 4000 rpm for 40 s at 25 °C. 300 μl of ethyl acetate antisolvent was added dropwise at the 30th second, and then annealed at 100 °C for 20 min to obtain the first perovskite thin film.

[0053] A C60 electron transport layer (30 nm) and a BCP hole blocking layer were evaporated on the surface of the first perovskite thin film prepared above to obtain a perovskite solar cell. The electron transport layer was transferred to a thermal evaporation device, and the copper electrode (Cu) was evaporated with a thickness of 100 nm under the condition that the vacuum degree reached 1×10-5 Pa to obtain a perovskite solar cell.

[0054] Example 3

[0055] This embodiment provides a second perovskite thin film and applies it to a perovskite solar cell. The specific composition and preparation method are as follows: Clean the glass, and sputter a 150-nm ITO thin film on the glass by magnetron sputtering; Spin-coat an aqueous solution of nickel oxide nanoparticles on the surface of the ITO thin film glass, with a concentration of 10 mg / ml, at a speed of 3000 revolutions per minute, and heat it on a hot plate at 100 °C for 10 min to obtain a dense nickel oxide thin film with a thickness of 15 nm. Dissolve lead iodide, lead bromide, formamidinium iodide, and cesium iodide with a molar ratio of 0.85:0.15:0.78:0.22 in a mixed solution composed of DMF and DMSO with a volume ratio of 4:1 to obtain a perovskite precursor solution; Take 200 μL of the perovskite precursor solution and evenly spread it on the side to be spin-coated with nickel oxide. Spin-coat it into a perovskite wet film at 25 °C at 4000 rpm for 40 s. Drop 300 μl of ethyl acetate antisolvent at the 30th second, and then anneal it at 100 °C for 20 min to obtain a 600-nm perovskite base film.

[0056] Dissolve a defect passivation molecule containing multiple active sites in isopropanol, and the addition ratio of the defect passivation molecule to isopropanol is 1 mg / ml to obtain a passivation solution. Spread the passivation solution evenly on one end of the surface of the prepared perovskite base film, spin-coat it at 4000 rpm for 20 s to form a film, and then anneal it at 100 °C for 20 min to obtain a passivation layer to complete the preparation of the second perovskite thin film.

[0057] Evaporate a C60 electron transport layer (30 nm) and a BCP hole blocking layer on the surface of the passivation layer prepared above to obtain a perovskite solar cell. Transfer the electron transport layer to a thermal evaporation device, and start evaporating a copper electrode (Cu) with a thickness of 100 nm under the condition that the vacuum degree reaches 1×10 -5 Pa to obtain a perovskite solar cell.

[0058] Example 4

[0059] This embodiment provides a second perovskite thin film and applies it to a perovskite solar cell. The specific composition and preparation method are as follows: Clean the glass, and sputter a 150-nm ITO thin film on the glass by magnetron sputtering; Spin-coat an aqueous solution of nickel oxide nanoparticles on the surface of the ITO thin film glass, with a concentration of 10 mg / ml, at a speed of 3000 revolutions per minute, and heat it on a hot plate at 100 °C for 10 min to obtain a dense nickel oxide thin film with a thickness of 15 nm. Dissolve lead iodide, lead bromide, formamidinium iodide, and cesium iodide with a molar ratio of 0.85:0.15:0.78:0.22 in a mixed solution composed of DMF and DMSO with a volume ratio of 4:1 to obtain a perovskite precursor solution; Take 200 μL of the perovskite precursor solution and evenly spread it on the side to be spin-coated with nickel oxide. Spin-coat it into a perovskite wet film at 25 °C at 4000 rpm for 40 s. Drop 300 μl of ethyl acetate antisolvent at the 30th second, and then anneal it at 100 °C for 20 min to obtain a 600-nm perovskite base film.

[0060] Dissolve a defect passivation molecule containing multiple active sites in isopropanol, where the addition ratio of the defect passivation molecule to isopropanol is 2 mg / ml to obtain a passivation solution. Spread the passivation solution evenly on one end of the surface of the prepared perovskite base film, spin-coat it at 4000 rpm for 20 s to form a film, and then anneal it at 100 °C for 20 min to obtain a passivation layer to complete the preparation of the second perovskite thin film.

[0061] Evaporate a layer of C60 electron transport layer (30 nm) and BCP hole blocking layer on the surface of the passivation layer prepared above to obtain a perovskite solar cell. Transfer the electron transport layer to a thermal evaporation device, and start evaporating a copper electrode (Cu) with a thickness of 100 nm under the condition that the vacuum degree reaches 1×10-5 Pa to obtain a perovskite solar cell.

[0062] Comparative Example 1

[0063] This comparative example provides a second perovskite thin film and applies it to a perovskite solar cell. The specific composition and preparation method are as follows: Clean the glass, and sputter a 150-nm ITO thin film on the glass by magnetron sputtering; Spin-coat an aqueous solution of nickel oxide nanoparticles on the surface of the ITO thin film glass, with a concentration of 10 mg / ml, at 3000 revolutions per minute, and heat it on a hot stage at 100 °C for 10 min to obtain a dense nickel oxide thin film with a thickness of 15 nm. Dissolve lead iodide, lead bromide, formamidinium iodide, and cesium iodide with a molar ratio of 0.85:0.15:0.78:0.22 in a mixed solution composed of DMF and DMSO with a volume ratio of 4:1 to obtain a perovskite precursor solution; Take 200 μL of the perovskite precursor solution and evenly spread it on the side to be spin-coated with nickel oxide, and spin-coat it into a perovskite wet film at 4000 rpm for 40 s at 25 °C. Add 300 μl of ethyl acetate antisolvent at the 30th second, and then anneal it at 100 °C for 20 min to obtain a 600-nm perovskite base film.

[0064] Evaporate a layer of C60 electron transport layer (30 nm) and BCP hole blocking layer on the surface of the perovskite base film prepared above to obtain a perovskite solar cell. Transfer the electron transport layer to a thermal evaporation equipment, and start evaporating the copper electrode (Cu) under the condition that the vacuum degree reaches 1×10 -5 Pa to obtain a perovskite solar cell with a thickness of 100 nm.

[0065] Experimental Example

[0066] Place the perovskite solar cells obtained in Example 1 and Comparative Example 1 in an aging environment at room temperature of 25 °C, relative humidity of 30%, and in the dark state for 1000 h to obtain Comparative Scheme 1 and Comparative Scheme 2. Use PCE to test the current density-voltage (JV) curves of the perovskite solar cells prepared in each example, comparative example, and comparative scheme. The test is completed on a Keithley 2400 system; Test conditions: The simulated light intensity is 100 mW cm -2 (AM 1.5G), the scanning rate is 0.1 V / s -1 (step size is 0.02 V, time delay is 200 ms), the scanning range is from 1.2 V to -0.2 V, and the power output of the xenon lamp is calibrated by a NERL (National Renewable Energy Laboratory) standard KG5 standard Si perovskite solar cell. The test results are shown in Table 1 and Figure 3 as follows.

[0067] Table 1 Detection results of perovskite solar cells in each example and comparative example

[0068]

[0069] As can be seen from Table 1 and Figure 3 it can be known that the fill factor of the perovskite solar cells in Examples 1-4 is relatively large. This is because the interfacial defects of the perovskite thin film formed by the passivation modification of the defect passivation molecules are reduced, and the series resistance of carrier transport is reduced. According to the comparison between Comparative Scheme 1 and Comparative Scheme 2 with Example 1 and Comparative Example 1 respectively, it can be known that after aging, the perovskite solar cell in Example 1 basically remains unchanged, indicating that the interfacial modification of the defect passivation molecules in this application can not only improve the photoelectric conversion efficiency of the perovskite solar cell, but also greatly enhance the stability of the perovskite solar cell under aging conditions.

[0070] It should be noted that in the description of this application, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of this application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0071] Any process or method description shown in the flowchart or described in other ways herein can be understood as representing a module, segment, or part of the code of executable instructions including one or more steps for implementing a specific logical function or process. The scope of the preferred embodiments of this application includes additional implementations, where the functions can be executed in a substantially simultaneous manner or in the reverse order according to the involved functions, rather than in the order shown or discussed, which should be understood by those skilled in the technical field to which the embodiments of this application belong.

[0072] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0073] Although the embodiments of this application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting this application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A method for preparing a perovskite film with deep defect passivation, characterized in that, It includes the following steps: Prepare a passivation solution using defect passivation molecules; Mix the passivation solution and the perovskite precursor solution in a set ratio to prepare a first perovskite thin film; Or Coat the passivation solution on at least one surface of the perovskite-based film formed by the perovskite precursor solution to form a passivation layer; after heat-treating the passivation layer and the perovskite-based film, obtain a second perovskite thin film; The defect passivation molecules inhibit the generation of halide anions and organic cations in the first perovskite thin film or the second perovskite thin film.

2. According to the preparation method described in claim 1, wherein, The passivation solution is obtained by dissolving the defect passivation molecules in a solvent. During the preparation of the first perovskite thin film, the addition ratio of the defect passivation molecules to the perovskite precursor solution is 1 mg / ml - 10 mg / ml; And / or; when preparing the second perovskite thin film, the addition ratio of the defect passivation molecules to the solvent is 0.1 mg / ml - 5 mg / ml; And / or; the solvent is at least one of isopropyl alcohol, trifluoroethanol, and hexafluoroisopropanol; and / or; the defect passivation molecule is a nitrogen-containing hybrid derivative, and its structural formula is 3. The preparation method according to claim 1 or 2, characterized in that, The preparation method of the perovskite precursor solution is: dissolve lead iodide, lead bromide, formamidinium iodide, and cesium iodide with a molar ratio of 0.85:0.15:0.78:0.22 in a mixed solution composed of DMF and DMSO with a volume ratio of 4:

1.

4. According to the preparation method described in claim 3, wherein, During the preparation of the first perovskite thin film, add the passivation solution to the perovskite precursor solution, and prepare a perovskite wet film with a thickness of 50 μm - 300 μm, and anneal at 100 °C for 20 - 30 min to obtain the first perovskite thin film.

5. The preparation method according to claim 3, characterized in that, During the preparation of the second perovskite thin film, the passivation layer is formed by coating or spin-coating.

6. According to the preparation method described in claim 5, it is characterized in that The heat treatment parameters of the passivation layer are 80 °C - 120 °C, lasting for 5 - 30 min.

7. The preparation method according to claim 6, characterized in that, The thickness of the passivation layer is 2 nm - 10 nm.

8. A perovskite thin film, characterized in that, Prepared by the preparation method according to any one of claims 1 - 7, including a first perovskite thin film or a second perovskite thin film.

9. A perovskite solar cell, characterized in that, Includes the perovskite thin film described in claim 8.

10. The perovskite solar cell according to claim 9, characterized in that, It also includes a substrate, a semiconductor material layer, a hole transport layer, a charge transport layer, and a metal layer; wherein, the first perovskite thin film or the second perovskite thin film is located between the hole transport layer and the charge transport layer.

Images