Perovskite thin film, preparation method thereof and perovskite solar cell

Abstract

The invention provides a perovskite thin film and a preparation method thereof, and a perovskite solar cell. The preparation method comprises the following steps: preparing an improved solution by using organic amine hydrochloride containing a plurality of acting sites; mixing the improved solution and a perovskite precursor solution according to a set proportion to prepare a first perovskite thin film; or coating at least one surface of the perovskite base film with the improvement solution to form an improvement layer; and carrying out heat treatment on the improved layer and the perovskite base film to obtain a second perovskite thin film. The organic amine hydrochloride and the perovskite precursor solution or the perovskite base film are utilized to form a low-dimensional perovskite thin film structure, so that energy level matching is optimized, and the water and oxygen erosion resistance of the first perovskite thin film or the second perovskite thin film is improved.

Description

Technical Field

[0001] This application relates to the technical field of perovskite solar cell preparation, and particularly relates to a perovskite thin film, a preparation method thereof, and a perovskite solar cell. Background Art

[0002] Due to its high photoelectric conversion efficiency and low-cost potential, perovskite solar cells have become a research hotspot in solar cells in recent years. However, there are often problems such as energy level mismatch, interface defects, and chemical instability at the interface between the perovskite material and the charge carrier transport layer, seriously affecting the performance and stability of the battery. In the prior art, the interface is usually improved by introducing an intermediate layer, surface passivation, or adjusting the thin film deposition process. However, these methods have limited effects and there is still much room for optimization. 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, a preparation method thereof, and a perovskite solar cell. This application uses organic amine hydrochloride to form a low-dimensional perovskite thin film structure with a perovskite base film or a perovskite precursor solution, thereby optimizing energy level matching and enhancing the water and oxygen erosion resistance of the perovskite thin film. In addition, the unprotonated nitrogen atom on the benzene ring in the organic amine hydrochloride structural formula can form a coordination interaction with lead ions in the perovskite base film or the perovskite precursor solution, passivate interface defects, and improve the optoelectronic performance of the 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 is proposed, including the following steps:

[0005] Prepare a modified solution using an organic amine hydrochloride containing multiple active sites;

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

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

[0008] In some embodiments, the modified solution is prepared by dissolving an organic amine hydrochloride containing multiple active sites in an alcohol solvent. During the preparation of the first perovskite thin film, the addition ratio of the organic amine hydrochloride to the perovskite precursor solution is 1 mg / ml - 10 mg / ml;

[0009] and / or; when preparing the second perovskite thin film, the addition ratio of the organic amine hydrochloride to the alcohol solvent is 0.1 mg / ml - 5 mg / ml;

[0010] and / or; the alcohol solvent is at least one of isopropyl alcohol, trifluoroethanol, and hexafluoroisopropanol;

[0011] and / or; the structural formula of the organic amine hydrochloride is

[0012] In some embodiments, the method for preparing 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.

[0013] In some embodiments, during the preparation of the first perovskite film, the modified 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.

[0014] In some embodiments, during the preparation of the second perovskite film, the modified layer is formed by coating or spin coating.

[0015] In some embodiments, the heat treatment parameters of the modified layer are 80 °C - 120 °C, lasting for 5 - 30 min.

[0016] In some embodiments, the thickness of the modified layer is 2 nm - 10 nm.

[0017] 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.

[0018] According to the third aspect of the present application, a perovskite solar cell is provided, which includes the perovskite film described in any of the above embodiments.

[0019] 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.

[0020] The additional aspects and advantages of the present application will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present application will become obvious and easy to understand from the following description of the embodiments in conjunction with the drawings, wherein:

[0022] Figure 1 It is a schematic structural diagram of the first perovskite thin film in an embodiment of the present application;

[0023] Figure 2 It is a schematic structural diagram of the second perovskite thin film in an embodiment of the present application.

[0024] Figure 3 It is the current-voltage curve graph of the battery in Example 1 and Comparative Example 1 of the present application and their corresponding aged ones. Detailed implementation manners

[0025] 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 represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application. On the contrary, the embodiments of the present application include all changes, modifications, and equivalents that fall within the spirit and connotation of the appended claims.

[0026] The present application is improved based on the following related technologies: Due to its high photoelectric conversion efficiency and low-cost potential, perovskite solar cells have become a research hotspot in solar cells in recent years. However, there are often problems such as energy level mismatch, interface defects, and chemical instability at the interface between the perovskite material and the carrier transport layer, which seriously affect the performance and stability of the battery. In the prior art, the interface is usually improved by introducing an intermediate layer, surface passivation, or adjusting the thin film deposition process. However, the effects of these methods are limited, and there is still much room for optimization.

[0027] The present application aims to solve at least one of the technical problems in the related technologies to a certain extent. To achieve the above purpose, according to the first aspect of the present application, a preparation method of a perovskite thin film is proposed, including the following steps:

[0028] S1: Prepare a modified solution by using an organic amine hydrochloride containing multiple active sites;

[0029] S2: Prepare a first perovskite thin film from a mixture obtained by mixing the modified solution and a perovskite precursor solution according to a set ratio; or form a modified layer by coating the modified solution on at least one surface of a perovskite-based film formed from the perovskite precursor solution; heat-treat the modified layer and the perovskite-based film to obtain a second perovskite thin film.

[0030] Among them, in S1, a modified solution is prepared by using an organic amine hydrochloride containing multiple active sites, where the organic amine hydrochloride is dissolved in an alcohol solvent, and the structural formula of the organic amine hydrochloride can be The alcohol solvent is at least one of isopropyl alcohol, trifluoroethanol, and hexafluoroisopropanol. Depending on the differences in the preparation of the first perovskite thin film and the second perovskite thin film, the organic amine hydrochloride 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 it.

[0031] In S2, during the preparation process of the exemplary first perovskite thin film, the modified solution is added to the perovskite precursor solution. During the preparation process of the first perovskite thin film, the addition ratio of the organic amine hydrochloride to the perovskite precursor solution is 1 mg / ml - 10 mg / ml; A perovskite wet film with a thickness of 50 μm - 300 μm is prepared using the mixed solution of the organic amine hydrochloride and the perovskite precursor solution, and annealing at 100 °C for 30 min can obtain the first perovskite thin film.

[0032] The addition ratio of the organic amine hydrochloride to the perovskite precursor solution is 1 mg / ml - 10 mg / ml. The exemplary addition ratios of the organic amine hydrochloride 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 organic amine hydrochloride is too large, such as greater than 10 mg / ml, the resistance of the first perovskite thin film increases, hindering the transport of carriers; conversely, if the addition ratio of the organic amine hydrochloride is too small, such as less than 1 mg / ml, the defect passivation effect of the organic amine hydrochloride is not obvious, and the passivation effect is poor.

[0033] A solution is obtained by mixing the above organic amine hydrochloride and the perovskite precursor solution, and a perovskite wet film with a thickness of 50 μm - 300 μm is prepared by spin coating / spraying / blade coating, etc., and then annealing at 100 °C for 20 - 30 min can obtain the first perovskite thin film. Among them, spin coating / spraying / blade coating, etc. can all adopt the conventional technical methods in the art, which will not be elaborated here.

[0034] In S2, in some embodiments, the preparation process of the second perovskite thin film is as follows: Prepare the perovskite precursor solution. The preparation method of the perovskite precursor solution refers to the above content and will not be elaborated here. The perovskite precursor solution is used to prepare a perovskite wet film with a set thickness by spin coating / spraying / blade coating, etc., and ethyl acetate antisolvent is dropped after the formation of the perovskite wet film for 30 s, and then annealing at 100 °C for 30 min can obtain the perovskite base film. The modified solution in any of the above embodiments is formed by coating or blade coating to form a modified layer on one surface of the perovskite base film, and then the heat treatment parameters of the modified layer are 80 °C - 120 °C for 5 - 30 min, and the thickness of the modified layer is 2 nm - 10 nm.

[0035] In the present application, the organic amine hydrochloride contains protonated nitrogen atoms and unprotonated nitrogen atoms. The amino groups containing protonated nitrogen atoms can passivate the cation-related defects in the perovskite film, and the unprotonated nitrogen atoms can form a coordination interaction with lead ions to passivate the lead ion-related defects.

[0036] According to the second aspect of the present application, a perovskite film is proposed, which includes the first perovskite film or the second perovskite film prepared by using the modification method in any of the above embodiments.

[0037] According to the third aspect of the present application, a perovskite solar cell is proposed, which includes the perovskite film in any of the above embodiments.

[0038] 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. The substrate can be a commercially available ITO film (including a glass plate), the semiconductor material layer can be nickel oxide (with a thickness of 20 nm, 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.

[0039] Among them, the first perovskite film is located between the hole transport layer and the charge transport layer as Figure 1 shown, the second perovskite film is located between the hole transport layer and the charge transport layer, and the modified layer in the second perovskite film faces the charge transport layer and / or the hole transport layer, as Figure 2 shown.

[0040] 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.

[0041] Example 1

[0042] 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 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 where nickel oxide is to be spin-coated. At room temperature of 25 °C, spin-coat it at 4000 rpm for 40 s to form a perovskite wet film. 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-based film.

[0043] Dissolve an organic amine hydrochloride containing multiple active sites in isopropanol, where the addition ratio of the organic amine hydrochloride to isopropanol is 0.5 mg / ml to obtain a modified solution. Spread the modified solution evenly on one end of the surface of the prepared perovskite-based 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 modified layer and complete the preparation of the second perovskite thin film.

[0044] Evaporate a layer of C60 electron transport layer (30 nm) and BCP hole blocking layer on the surface of the above-prepared modified layer 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.

[0045] Example 2

[0046] This embodiment provides a first 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.

[0047] Dissolve an organic amine hydrochloride containing multiple active sites in isopropanol. The organic amine hydrochloride and isopropanol are mixed to obtain a modified solution. After mixing the modified solution with the perovskite precursor solution at an addition ratio of 1 mg / ml, spin-coat it into a 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 at 100°C for 20 min to obtain the first perovskite film.

[0048] Evaporate a layer of C60 electron transport layer (30 nm) and BCP hole blocking layer on the surface of the first perovskite 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) with a thickness of 100 nm under the condition that the vacuum degree reaches 1×10 -5 Pa to obtain a perovskite solar cell.

[0049] Example 3

[0050] This example provides a second perovskite 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 film on the glass by magnetron sputtering; Spin-coat an aqueous solution of nickel oxide nanoparticles on the surface layer of the ITO 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 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 one side of the nickel oxide to be spin-coated, 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 at 100°C for 20 min to obtain a 600-nm perovskite-based film.

[0051] Dissolve an organic amine hydrochloride containing multiple active sites in isopropanol. The addition ratio of the organic amine hydrochloride to isopropanol is 1 mg / ml to obtain a modified solution. Spread the modified solution evenly on one end of the prepared perovskite-based film surface, spin-coat it at 4000 rpm for 20 s to form a film, and then anneal at 100°C for 20 min to complete the preparation of the second perovskite film with a modified layer.

[0052] Evaporate a layer of C60 electron transport layer (30 nm) and BCP hole blocking layer on the surface of the modified layer 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) with a thickness of 100 nm under the condition that the vacuum degree reaches 1×10-5 Pa to obtain a perovskite solar cell.

[0053] Example 4

[0054] This 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 at 10 mg / ml, 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 one side of the nickel oxide to be spin-coated, and spin-coat it into a perovskite wet film at 4000 rpm for 40 s at room temperature of 25 °C. 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-based film.

[0055] Dissolve an organic amine hydrochloride containing multiple active sites in isopropanol, and the addition ratio of the organic amine hydrochloride to isopropanol is 2 mg / ml to obtain a modified solution. Spread the modified solution evenly on one end of the surface of the prepared perovskite-based 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 modified layer to complete the preparation of the second perovskite thin film.

[0056] Evaporate a layer of C60 electron transport layer (30 nm) and BCP hole blocking layer on the surface of the above-prepared modified layer 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.

[0057] Comparative Example 1

[0058] 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 layer 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 25 °C at 4000 rpm for 40 s. 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-based film.

[0059] The addition ratio of phenethylamine hydroiodide to isopropanol is 0.5 mg / ml to obtain a modified solution. Spread the modified solution evenly on one end of the surface of the prepared perovskite-based 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 modified layer to complete the preparation of the second perovskite thin film.

[0060] Evaporate a layer of C60 electron transport layer (30 nm) and BCP hole blocking layer on the surface of the above-prepared modified layer 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.

[0061] Experimental example

[0062] Age the perovskite solar cells obtained in Example 1 and Comparative Example 1 on a hot stage at 80 °C, with a relative humidity of 80%, and an aging time of 500 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 kethley2400 system; Test conditions: The simulated light intensity is 100 mW cm -2 (AM 1.5G), the scanning rate is 0.1 V / s -1 (The step size is 0.02 V, and the 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 shown.

[0063] Table 1 Detection Results of Perovskite Solar Cells in Each Example and Comparative Example

[0064] Open-circuit voltage (V) <![CDATA[Short-circuit current (mA / cm 2 )]]> Fill factor (%) Photovoltaic conversion efficiency (%) Example 1 1.23 19.55 85.47 20.60 Example 2 1.23 19.51 85.16 20.38 Example 3 1.22 19.31 85.07 20.08 Example 4 1.21 19.37 84.37 19.73 Comparative scheme 1 1.21 19.50 84.48 19.93 Comparative example 1 1.21 19.13 81.65 18.86 Comparative scheme 2 1.20 18.11 62.66 13.66

[0065] From Table 1 and Figure 3 it can be seen that from the photoelectric conversion efficiency in Examples 1-4, when comparing the optimal concentration-modified battery parameters, when the addition concentration of the organic amine hydrochloride is slightly larger, a thicker two-dimensional material layer is formed, which affects the carrier transport and reduces the current of the perovskite solar cell. Compared with the passivation using phenethylamine hydroiodide in Comparative Example 1, the organic amine hydrochloride used in this application for the preparation of the perovskite thin film has better effects in improving the open-circuit voltage, short-circuit current and fill factor parameters of the perovskite solar cell when applied. According to the comparison between Comparative Scheme 1 and Comparative Scheme 2 with Example 1 and Comparative Example 1 respectively, it can be seen that the perovskite solar cell has higher stability after accelerated aging.

[0066] 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.

[0067] Any process or method description shown in the flowchart or described in other ways herein can be understood to represent a module, segment or part of code including one or more executable instructions for implementing a specific logical function or process, and 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.

[0068] 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.

[0069] 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 thin film, characterized in that, It includes the following steps: Prepare a modified solution by using an organic amine hydrochloride containing multiple active sites; Mix the modified solution and the perovskite precursor solution in a set ratio to prepare a first perovskite film; Or Coat the modified solution on at least one surface of a perovskite-based film formed from the perovskite precursor solution to form a modified layer; heat-treat the modified layer and the perovskite-based film to obtain a second perovskite film.

2. According to the preparation method described in claim 1, characterized in that, The modified solution is prepared by dissolving an organic amine hydrochloride containing multiple active sites in an alcohol solvent. During the preparation of the first perovskite film, the addition ratio of the organic amine hydrochloride to the perovskite precursor solution is 1 mg / ml - 10 mg / ml; And / or; when preparing the second perovskite film, the addition ratio of the organic amine hydrochloride to the alcohol solvent is 0.1 mg / ml - 5 mg / ml; And / or; the alcohol solvent is at least one of isopropyl alcohol, trifluoroethanol, and hexafluoroisopropanol; and / or; The structural formula of the organic amine hydrochloride 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, characterized in that, During the preparation of the first perovskite film, add the modified solution to the perovskite precursor solution, and prepare a perovskite wet film with a thickness of 50 μm - 300 μm, and anneal it at 100 °C for 20 - 30 min to obtain the first perovskite film.

5. According to the preparation method described in claim 3, characterized in that, During the preparation of the second perovskite film, the modified layer is formed by coating or spin-coating.

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

7. The method according to claim 6, wherein The thickness of the modified layer is 2 nm - 10 nm.

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

9. A perovskite solar cell, characterized in that, It includes the perovskite film described in claim 8.

10. The perovskite solar cell according to claim 9, characterized in that, It 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.

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