Perovskite thin film and preparation method thereof, perovskite solar cell, and electric device

Abstract

The application discloses a perovskite thin film and a preparation method thereof, a perovskite solar cell and an electric device, and belongs to the technical field of solar cells. The preparation method of the perovskite thin film comprises the following steps: coating a perovskite precursor solution on a surface of a substrate to prepare a substrate provided with a perovskite liquid film; and placing the substrate provided with the perovskite liquid film with the perovskite liquid film facing downward, vacuum flash evaporation to prepare the perovskite thin film. The substrate provided with the perovskite liquid film is placed with the perovskite liquid film facing downward, vacuum flash evaporation to prepare the perovskite thin film. In the process of rapid evaporation of the solvent in the perovskite liquid film, due to the existence of gravity, the influence of solvent evaporation from top to bottom on the uniformity and crystal quality of the perovskite thin film is greatly reduced, which is helpful to uniform evaporation of the solvent, reduces internal stress and interface defects of the thin film, effectively improves the uniformity and crystal quality of the perovskite thin film, and thus improves the photoelectric conversion efficiency of the perovskite assembly.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a perovskite thin film and a preparation method thereof, a perovskite solar cell and an electric device. BACKGROUND

[0002] Perovskite materials have become an important research direction in the field of solar cells due to their excellent photoelectric conversion efficiency and low preparation cost. During the preparation of perovskite thin films on a large scale, the coated perovskite wet film needs to be dried. Vacuum drying crystallization (VCD) is an important method for treating perovskite wet films at present. By quickly reaching a process vacuum environment, VCD can effectively remove the solvent in the perovskite thin film, promote the crystallization and uniformity of the thin film, and thus improve the photoelectric performance.

[0003] However, the drying effect of VCD is closely related to the orientation of the substrate. In the conventional VCD drying method, the assembly coated with perovskite precursors is usually placed upright (i.e. the perovskite liquid film faces upward) for drying. Due to the uneven pumping speed and inconsistent crystallization rate of the solution, the thin film may have incomplete crystallization and discontinuity defects. In addition, the solvent volatilizes from bottom to top, and the perovskite thin film is prone to pinholes, which greatly affects the uniformity and crystal quality of the perovskite thin film and limits the photoelectric conversion efficiency of the perovskite assembly. SUMMARY

[0004] Therefore, the main purpose of the present application is to provide a preparation method of a perovskite thin film. By placing the substrate with a perovskite liquid film on the surface with the perovskite liquid film facing downward for vacuum drying, the uniformity and crystal quality of the perovskite thin film are effectively improved, and thus the photoelectric conversion efficiency of the perovskite assembly is improved.

[0005] In a first aspect, the present application provides a preparation method of a perovskite thin film, comprising the following steps:

[0006] coating a perovskite precursor solution on the surface of a substrate to prepare a substrate with a perovskite liquid film on the surface;

[0007] placing the substrate with the perovskite liquid film on the surface with the perovskite liquid film facing downward for vacuum flash evaporation to prepare a perovskite thin film.

[0008] In the present application, the substrate with the perovskite liquid film on the surface is placed with the perovskite liquid film facing downward for vacuum flash evaporation to prepare a perovskite thin film. During the rapid volatilization of the solvent in the perovskite liquid film, the influence of the volatilization of the solvent from top to bottom on the uniformity and crystal quality of the perovskite thin film is greatly reduced due to the presence of gravity, which is helpful for the uniform volatilization of the solvent, reduces the internal stress and interface defects of the thin film, effectively improves the uniformity and crystal quality of the perovskite thin film, and thus improves the photoelectric conversion efficiency of the perovskite assembly.

[0009] In some embodiments, the conditions of the vacuum flash include: 25s-60s flash to 2Pa-20Pa, 0s-6s pressure maintaining.

[0010] In some embodiments, the conditions of the vacuum flash include: 25s-35s flash to 2Pa-4Pa, 0s-6s pressure maintaining.

[0011] In some embodiments, the coating method includes slot coating and / or doctor blade coating.

[0012] In some embodiments, the solute concentration of the perovskite precursor solution is 1.0mmol-1.4mmol.

[0013] In some embodiments, the solvent of the perovskite precursor solution includes at least one of N,N-dimethylformamide, dimethyl sulfoxide and N-methyl-2-pyrrolidone.

[0014] The second aspect of the present application provides a perovskite thin film prepared by the method for preparing a perovskite thin film according to the first aspect.

[0015] The third aspect of the present application provides a perovskite solar cell comprising the perovskite thin film according to the second aspect.

[0016] In some embodiments, the perovskite solar cell comprises an electrically conductive substrate, a hole transport layer, a perovskite thin film, an electron transport layer, a buffer layer and a back electrode arranged in a stack.

[0017] The fourth aspect of the present application provides an electric device comprising the perovskite solar cell according to the third aspect.

[0018] The beneficial effects of the present application are as follows:

[0019] 1、The present application places the substrate with perovskite liquid film on the surface with the perovskite liquid film facing downward, and then performs vacuum flash to prepare a perovskite thin film. In the process of rapid evaporation of the solvent in the perovskite liquid film, the influence of the solvent evaporation from top to bottom on the uniformity and crystal quality of the perovskite thin film is greatly reduced due to the presence of gravity, which helps the uniform evaporation of the solvent, reduces the internal stress and interface defects of the thin film, and effectively improves the uniformity and crystal quality of the perovskite thin film, thereby improving the photoelectric conversion efficiency of the perovskite module.

[0020] 2、The present application optimizes the drying process of the perovskite liquid film, and provides a new technical path for the efficient preparation of a perovskite thin film, which is especially suitable for large-area preparation of a perovskite thin film. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and should not be considered as limiting the present application. In the entire drawings, the same reference signs represent the same components. In the drawings:

[0022] Figure 1 XRD patterns of the perovskite thin films of Example 1 and Comparative Example 1;

[0023] Figure 2 SEM images of the perovskite thin films of Example 1 and Comparative Example 1;

[0024] Figure 3 J-V curves of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0025] In order to make the purposes, technical solutions and advantages of the present application more clear, and to make the understanding of the disclosure of the present application more thorough and comprehensive, the technical solutions of the present application will be described below in conjunction with the specific embodiments of the present application and the corresponding drawings. The described embodiments are only some of the embodiments of the present application, not all the embodiments.

[0026] The embodiments of the present application will be described in detail below in conjunction with the drawings. The present embodiment is implemented on the premise of the technical solutions of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0027] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the present application in the specification are only for the purpose of describing the specific embodiments and are not intended to limit the present application.

[0028] Unless otherwise stated or contradictory, the terms or phrases used in the present application have the following meanings:

[0029] In the present application, "a plurality of", "a plurality of", etc. are not specifically limited, which means more than two or equal to two in quantity. For example, "one or more", "at least one" means one or more than two.

[0030] In the present application, "further", "particularly" and the like are used for the purpose of description, which means the difference in content, but should not be understood as limiting the protection scope of the present application.

[0031] In the present application, the technical features described in an open manner include a closed technical solution consisting of listed features, and also includes an open technical solution containing listed features.

[0032] In the present application, when referring to a numerical interval (i.e. a numerical range), the distribution of the selectable values within the numerical interval is considered continuous and includes both numerical endpoints (i.e. the minimum and maximum values) of the numerical interval and every value between the two numerical endpoints, unless otherwise specified. When a numerical interval refers only to integers within the numerical interval, including both endpoints and every integer between the two endpoints, it is equivalent to listing each integer directly, unless otherwise specified. When multiple numerical ranges are provided to describe a feature or characteristic, the numerical ranges can be combined. In other words, unless otherwise indicated, numerical ranges disclosed in the present application are to be understood to include any and all sub-ranges considered therein. A "value" in a numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. A "numerical interval" is intended to broadly include numerical interval types such as percentage intervals, ratio intervals, value intervals, etc.

[0033] In the present application, unless otherwise specified, a temperature parameter allows for both constant temperature treatment and treatment within a certain temperature interval. It should be understood that the constant temperature treatment allows for fluctuations within the accuracy of the instrument control. Fluctuations within a range such as ±5°C, ±4°C, ±3°C, ±2°C and ±1°C are allowed.

[0034] The term "and / or", as used in the present application, includes any and all combinations of one or more of the associated listed items.

[0035] In the present application, unless otherwise specified, the percentage content refers to mass percentage for solid-liquid mixing and solid-solid mixing, and refers to volume percentage for liquid-liquid mixing.

[0036] In the present application, unless otherwise specified, the percentage concentration refers to the final concentration. The final concentration refers to the proportion of the added ingredient in the system after the ingredient is added.

[0037] In the present application, unless otherwise specified, a temperature parameter allows for both constant temperature treatment and treatment within a certain temperature interval. The constant temperature treatment allows for fluctuations within the accuracy of the instrument control. Room temperature, as used in the present application, refers to 0-40°C, preferably 10-35°C, and further preferably 20-30°C.

[0038] In a first aspect, the present application provides a method for preparing a perovskite thin film, comprising the following steps:

[0039] coating a perovskite precursor solution on a substrate surface to prepare a substrate with a perovskite liquid film on the surface;

[0040] maintaining the substrate with the perovskite liquid film on the surface with the perovskite liquid film facing downward, and performing vacuum flash evaporation to prepare a perovskite thin film.

[0041] The application places the substrate with the perovskite liquid membrane on the surface downward, performs vacuum flash evaporation, and prepares a perovskite thin film. In the process of rapid evaporation of the solvent in the perovskite liquid membrane, the influence of the downward evaporation of the solvent on the uniformity and crystal quality of the perovskite thin film is greatly reduced due to the presence of gravity, which helps uniform evaporation of the solvent, reduces internal stress and interface defects of the thin film, effectively improves the uniformity and crystal quality of the perovskite thin film, and thus improves the photoelectric conversion efficiency of the perovskite component.

[0042] In some embodiments, after the vacuum flash evaporation to form the perovskite dry film, a step of annealing and crystallization is further included; the conditions of annealing and crystallization include keeping the perovskite dry film upward, annealing at 140-160℃ for 5-15min.

[0043] In a specific example, the annealing temperature can be 140℃, 145℃, 150℃, 155℃, 160℃, etc., and the annealing time can be 5min, 6min, 8min, 10min, 12min, 14min, 15min, etc.

[0044] In some embodiments, the conditions of vacuum flash evaporation include flash evaporation to 2-20Pa for 25-60s and pressure maintaining for 0-6s.

[0045] In some embodiments, the conditions of vacuum flash evaporation include flash evaporation to 2-4Pa for 25-35s and pressure maintaining for 0-6s.

[0046] In a specific example, the conditions of vacuum flash evaporation include flash evaporation to 2Pa, 4Pa, 6Pa, 10Pa, 12Pa, 14Pa, 16Pa, 18Pa, 20Pa for 25s, 30s, 35s, 40s, 45s, 50s, 55s, 60s and pressure maintaining for 0s, 1s, 2s, 3s, 4s, 5s, 6s.

[0047] In some embodiments, the coating method includes slot coating and / or doctor blade coating.

[0048] In some embodiments, the solute concentration of the perovskite precursor solution is 1.0-1.4mmol.

[0049] In some embodiments, the solvent of the perovskite precursor solution includes at least one of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N-methyl-2-pyrrolidone (NMP).

[0050] In some embodiments, the solvent of the perovskite precursor solution is N,N- dimethylformamide and N-methyl-2-pyrrolidone in a volume ratio of 5-15:1 (e.g., 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1).

[0051] In a second aspect of the present application, there is provided a perovskite thin film prepared by the method of preparing a perovskite thin film according to the first aspect.

[0052] In a third aspect of the present application, there is provided a perovskite solar cell comprising the perovskite thin film according to the second aspect.

[0053] In some embodiments, the perovskite solar cell comprises an electrically conductive substrate, a hole transport layer, a perovskite thin film, an electron transport layer, a buffer layer and a back electrode arranged in a stack.

[0054] In a specific example, the electrically conductive substrate is an FTO substrate.

[0055] In a specific example, the hole transport material of the hole transport layer comprises one of NiOx, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) and a self-assembled monolayer material.

[0056] In one specific example, the self-assembled monolayer material comprises [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz), [3-(3,6-dimethoxy-9H-carbazol-9-yl)propyl]phosphonic acid (MeO-3PACz), [6-(3,6-dimethoxy-9H-carbazol-9-yl)hexyl]phosphonic acid (MeO-6PACz), [2-(3,6-dimethyl-9H-carbazol-9-yl)ethyl]phosphonic acid (Me-2PACz), [3-(3,6-dimethyl-9H-carbazol-9-yl)propyl]phosphonic acid (Me-3PACz), [6-(3,6-dimethyl-9H-carbazol-9-yl)hexyl]phosphonic acid (Me-6PACz), [1-(3,6-dimethyl-9H-carbazol-9-yl)methyl]phosphonic acid (Me-1PACz), [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz), [8-(3,6-dimethyl-9H-carbazol-9-yl)octyl]phosphonic acid (Me-8PACz), [1-(9H-carbazol-9-yl)methyl]phosphonic acid (1PACz), (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz), [3-(9H-carbazol-9-yl)propyl]phosphonic acid (3PACz), [4-(9H-carbazol-9-yl)butyl]phosphonic acid (4PACz), [6-(9H-carbazol-9-yl)hexyl]phosphonic acid (6PACz), [8-(9H-carbazol-9-yl)octyl]phosphonic acid (8PACz), [4-(N,N-di(4-methoxyphenylamino)phenyl)propyl]phosphonic acid (MeO-TPA-3PA), 2,3,4,5,6-pentafluorobenzylphosphonic acid (F5BPA), [2-(9H-9'-phenyl-3,3'-bicarbazol-9-yl)ethyl]phosphonic acid (2PABCz), [4-(9H-9'-phenyl-3,3'-bicarbazol-9-yl)butyl]phosphonic acid (4PABCz), [4-(diphenylamino)phenyl)ethyl]phosphonic acid (TPA-2PA), [4-(diphenylamino)phenyl)propyl]phosphonic acid (TPA-3PA), [4-(10H-phenothiazin-10-yl)butyl]phosphonic acid (4PAPT), [2-(7H-dibenzo-carbazol-7-yl)ethyl]phosphonic acid (2PADCB), [4-(7H-dibenzo-carbazol-7-yl)butyl]phosphonic acid (4PADCB), [3-(3,6-dibromo-9H-carbazol-9-yl)propyl]phosphonic acid (2Br-3PACz), [4-(3,6-dibromo-9H-carbazol-9-yl)butyl]phosphonic acid (2Br-4PACz), [6-(3,6-dibromo-9H-carbazol-9-yl)hexyl]phosphonic acid (2Br-6PACz), [1-(3,6-di-tert-butyl-9H-carbazol-9-yl)methyl]phosphonic acid (tBu-1PACz), [2-(3,6-di-tert-butyl-9H-carbazol-9-yl)ethyl]phosphonic acid (tBu-2PACz), [3-(3,6-di-tert-butyl-9H-carbazol-9-yl)propyl]phosphonic acid (tBu-3PACz), [4-(3,6-di-tert-butyl-9H-carbazol-9-yl)butyl]phosphonic acid (tBu-4PACz), [6-(3,6-di-tert-butyl-9H-carbazol-9-yl)hexyl]phosphonic acid (tBu-6PACz), [8-(3,6-di-tert-butyl-9H-carbazol-9-yl)octyl]phosphonic acid (tBu-8PACz), [1-(3,6-diphenyl-9H-carbazol-9-yl)methyl]phosphonic acid (Ph-1PACz), [2-(3,6-diphenyl-9H-carbazol-9-yl)ethyl]phosphonic acid (Ph-2PACz), [3-(3,6-diphenyl-9H-carbazol-9-yl)propyl]phosphonic acid (Ph-3PACz), [4-(3,6-diphenyl-9H-carbazol-9-yl)butyl]phosphonic acid (Ph-4PACz), [6-(3,6-diphenyl-9H-carbazol-9-yl)hexyl]phosphonic acid (Ph-6PACz), [8-(3,6-diphenyl-9H-carbazol-9-yl)octyl]phosphonic acid (Ph-8PACz), [2-(10H-phenoxazine-10-yl)ethyl]phosphonic acid (2PAPXZ), [4-(3,7-dibromo-10H-phenothiazine-10-yl)butyl]phosphonic acid (2Br-4PAPT), and [4-(3,7-dibromo-10H-phenoxazine-10-yl)butyl]phosphonic acid (2Br-4PAPXZ).

[0057] In one specific example, the material of the perovskite layer comprises a perovskite.

[0058] In one specific example, the perovskite has a general formula of AB(X n Y 1-n )3, where A is a monovalent cation, B is a divalent metal ion, X, Y are each independently a halide anion, and 0≤n≤1.

[0059] In one specific example, A comprises at least one of FA cation, MA cation, Cs cation, and Rb cation; and B comprises at least one of Pb cation and Sn cation.

[0060] In one specific example, the electron transport layer is an n-type semiconductor.

[0061] In one specific example, the material of the electron transport layer comprises C60 and / or PCBM.

[0062] In one specific example, the material of the buffer layer comprises ALD SnO2 and / or BCP.

[0063] In one specific example, the material of the electrode includes at least one of ITO, IZO, and Cu.

[0064] In a fourth aspect of the present application, a perovskite solar cell is provided.

[0065] The raw materials used in the following tests are commercially available unless otherwise specified.

[0066] The following are specific examples.

[0067] Example 1

[0068] 1) P1 scribe line was made on the FTO substrate (200mm x 200mm), and then the substrate was cleaned with deionized water, acetone and isopropanol for 15 minutes each. After cleaning, the substrate was dried with a nitrogen gun and placed in an ultraviolet ozone cleaning machine for 20 minutes to obtain a treated FTO substrate.

[0069] 2) The prepared hole transport layer solution (0.5mg / mL MeO-2PACz methanol solution) was coated on the treated FTO substrate by slot coating, and then placed on a hot stage for annealing at 100°C for 10 minutes. After cooling to room temperature, a conductive substrate with a hole transport layer (5nm) was obtained.

[0070] 3) The prepared perovskite precursor solution (1.2mmol FA 0.995 Cs 0.05 PbI3 in a volume ratio of 9:1 DMF and NMP mixed solution) was slot coated on the conductive substrate with a hole transport layer to form a perovskite liquid film on the surface of the hole transport layer. Then, the substrate was transferred to a vacuum flash evaporation device, with the perovskite liquid film facing down. The perovskite liquid film was flash evaporated to 3Pa for 30 seconds and kept for 5 seconds to form a perovskite dry film. The perovskite dry film was kept facing up and annealed at 150°C for 10 minutes to crystallize. The preparation of a perovskite thin film (500nm) on the surface of the hole transport layer was completed.

[0071] 4) C 60 After the deposition of the electron transport layer (25nm) and the buffer layer (BCP, 8nm) on the perovskite thin film, P2 laser scribe line was made. After the preparation of the back electrode (120nm Cu), P3 laser scribe line was made. Finally, P4 laser edge cleaning was performed to complete the preparation of the perovskite solar cell module.

[0072] In step 3), the perovskite thin film surface is black and shiny.

[0073] Example 2

[0074] Except that the flash evaporation condition in step 3) is replaced with 60s flash evaporation to 2Pa and 0s pressure keeping, the rest is the same as example 1.

[0075] Example 3

[0076] Except that 1.2 mmol of FA was used in step 3) 0.88 Cs 0.12 PbI3in a mixed solution of DMF and NMP with a volume ratio of 9:1, and the rest was the same as in Example 1.

[0077] Example 4

[0078] Except that 1.2 mmol of Cs was used in step 3) 0.22 FA 0.78 Pb(I 1-x Br x )3(where x is 0.2) in a mixed solution of DMF and NMP with a volume ratio of 9:1, and the rest was the same as in Example 1.

[0079] Comparative Example 1

[0080] Except that the perovskite liquid film was kept facing up for vacuum flash evaporation in step 3), and the rest was the same as in Example 1.

[0081] Comparative Example 2

[0082] Except that the perovskite liquid film was kept facing up for vacuum flash evaporation in step 3), and the rest was the same as in Example 1, and the perovskite thin film surface prepared in step 3) was white.

[0083] Comparative Example 3

[0084] Except that the perovskite liquid film was kept facing up for vacuum flash evaporation in step 3), and the rest was the same as in Example 3.

[0085] Test Example

[0086] 1. XRD analysis of the perovskite thin films obtained in Example 1 and Comparative Example 1 was performed using a Bruker X-ray diffractometer, and the results are shown in Figure 1 From the figure, it can be seen that the diffraction intensity of the perovskite thin film of inverted flash evaporation is higher, which means that the crystallization is better, and the photoelectric conversion efficiency is higher.

[0087] 2. Morphology analysis of the perovskite thin films obtained in Example 1 and Comparative Example 1 was performed using a scanning electron microscope (FEI-SEM (XL 30 S-FEG)), and the results are shown in Figure 2 From the figure, it can be seen that the crystal of the perovskite thin film of inverted flash evaporation is larger, the pinhole is smaller, and the light spot efficiency is higher.

[0088] 3. The perovskite solar cell components prepared in the examples and comparative examples were tested under a solar simulator (Zolix SS150A, 100 mw / cm 2Performance tests were carried out, and the results are shown in Table 1. The J-V curve diagrams of Example 1 and Comparative Example 1 are shown in Figures 1 and 2, respectively. Figure 3 .

[0089] Table 1: Performance summary of examples and comparative examples

[0090]

[0091] As can be seen from Table 1, Examples 1-4, which placed the substrate with the perovskite liquid film with the perovskite liquid film facing downward (i.e., inverted drying) for vacuum flash evaporation, all obtained good photoelectric efficiency, significantly better than Comparative Examples 1-3. It can be seen that keeping the perovskite liquid film facing downward for drying (inverted drying) is conducive to improving the uniformity and crystal quality of the perovskite thin film, thereby improving the photoelectric conversion efficiency of the perovskite module.

[0092] At the same time, as shown in Comparative Example 2, keeping the perovskite liquid film facing upward (normal drying) during the drying stage and keeping the perovskite liquid film facing downward (inverted annealing crystallization) during the annealing crystallization stage will not be conducive to the uniformity and crystal quality of the perovskite thin film, and the photoelectric conversion efficiency of the perovskite module will be significantly degraded.

[0093] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, however, as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present disclosure.

[0094] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of the present application. Therefore, the scope of protection of the patent of the present application should be subject to the appended claims.

Claims

1. A method for preparing a perovskite thin film, characterized by, The method comprises the following steps: coating a perovskite precursor solution on a substrate surface to prepare a substrate with a perovskite liquid film on the surface; placing the substrate with the perovskite liquid film on the surface with the perovskite liquid film facing downward, and performing vacuum flash evaporation to improve the uniformity and crystal quality of the perovskite thin film, thereby preparing the perovskite thin film; the conditions of the vacuum flash evaporation include: flash evaporation for 25-60 s to 2-20 Pa, and pressure maintaining for 0-6 s; the coating method is slot coating and / or doctor blade coating.

2. The method for preparing perovskite thin films according to claim 1, characterized in that, the conditions of the vacuum flash evaporation include: flash evaporation for 25-35 s to 2-4 Pa, and pressure maintaining for 0-6 s.

3. The method for preparing perovskite thin films as described in claim 1 or 2, characterized in that, the solute concentration of the perovskite precursor solution is 1.0-1.4 mmol.

4. The method for preparing perovskite thin films as described in claim 1 or 2, characterized in that, the solvent of the perovskite precursor solution comprises at least one of N,N-dimethylformamide, dimethyl sulfoxide and N-methyl-2-pyrrolidone.

5. The perovskite thin film prepared by the method of any one of claims 1-4.

6. A perovskite solar cell, characterized by, The perovskite thin film of claim 5.

7. The perovskite solar cell of claim 6, wherein the perovskite layer is formed by a two-step method. The perovskite solar cell comprises a conductive substrate, a hole transport layer, a perovskite thin film, an electron transport layer, a buffer layer and a back electrode which are arranged in layers.

8. An electrical device, characterized by The perovskite solar cell of claim 6 or 7. The perovskite solar cell of claim 6 or 7.

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