Perovskite precursor solution, perovskite thin film, perovskite solar cell and preparation method

Abstract

The invention belongs to the photovoltaic field, and particularly relates to a perovskite precursor solution, a perovskite thin film, a perovskite solar cell and a preparation method. A solvent of the perovskite precursor solution comprises N, N-dimethylformamide and tetramethylurea in a volume ratio of (3-20): 1. The solvent of the perovskite precursor solution is cheap and pollution-free, and the perovskite precursor solution can be used for improving the film forming quality of a perovskite film and improving the open-circuit voltage and the energy conversion efficiency of a perovskite solar cell.

Description

Technical Field

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

[0002] Perovskite solar cells are expected to become a new generation of photovoltaic technology due to their high energy conversion efficiency and low preparation cost. However, this photovoltaic technology is still in the transition stage from laboratory to mass production. On the one hand, since the preparation components of perovskite include organic ammonium salts, lead halides and other chemical substances, a simple manufacturing process of "organic solvent dissolution" + "coating annealing crystallization" is required to prepare perovskite films, so it is very important to choose a suitable solvent to manufacture high-quality perovskite films; on the other hand, considering that this photovoltaic technology will be adapted to industrialization for large-scale mass production, the amount of solvent used is large, so choosing a cheap, green and pollution-free solvent is of great significance to accelerate its commercialization.

[0003] At present, the commonly used solvents for preparing perovskite films are N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), 2-methoxyethanol (ME), etc. The solvents currently used evaporate quickly and cannot effectively control the nucleation and crystallization rate of perovskite structure materials during annealing, resulting in smaller grains of perovskite films, more defects inside, increased non-radiative recombination, and loss of open circuit voltage, which limits the further improvement of energy conversion efficiency.

[0004] Therefore, it is urgent to develop a cheap and pollution-free perovskite precursor solvent to improve the film quality of perovskite thin films, thereby improving the open circuit voltage and energy conversion efficiency of perovskite solar cells. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a perovskite precursor solution, a perovskite film, a preparation method thereof, a perovskite solar cell and a preparation method thereof. The solvent of the perovskite precursor solution of the present invention includes N,N-dimethylformamide, dimethyl sulfoxide and tetramethyl urea, and the solvent has a strong interaction with the lead salt in the perovskite component, effectively delaying and regulating the crystallization process of the perovskite structure material, expanding the process window for the manufacture of the perovskite structure material, thereby increasing the grain size, reducing the defects of the perovskite film, and further improving the open circuit voltage and energy conversion efficiency of the perovskite solar cell.

[0006] Specifically, the present invention provides a perovskite precursor solution, wherein the solvent of the perovskite precursor solution includes N,N-dimethylformamide and tetramethylurea; in the solvent of the perovskite precursor solution, the volume ratio of N,N-dimethylformamide to tetramethylurea is (3-20):1.

[0007] In one or more embodiments, in the solvent of the perovskite precursor solution, the volume ratio of N,N-dimethylformamide to tetramethylurea is (8-20):1.

[0008] In one or more embodiments, in the solvent of the perovskite precursor solution, the volume ratio of N,N-dimethylformamide to tetramethylurea is (16-20):1.

[0009] In one or more embodiments, the solvent of the perovskite precursor solution further includes dimethyl sulfoxide.

[0010] In one or more embodiments, the volume ratio of dimethyl sulfoxide to N,N-dimethylformamide is (0.001-0.5):1.

[0011] In one or more embodiments, the raw materials of the perovskite precursor solution include a first precursor compound and a second precursor compound of a perovskite structure material, the chemical formula of the first precursor compound is AX, and the chemical formula of the second precursor compound is BX2; wherein the A ion is selected from one or more of formamidinium ion, cesium ion, methylamine ion, dimethylamine ion, guanidine ion, potassium ion and rubidium ion, the B ion is lead ion and / or tin ion, and the X ion is selected from one or more of bromide ion, iodide ion, chloride ion, thiocyanate ion and fluoroborate ion.

[0012] In one or more embodiments, the concentration of the B ions in the perovskite precursor solution is 1-2 mol / L.

[0013] The invention provides a method for preparing a perovskite film, which comprises coating the perovskite precursor solution of the invention and then annealing to obtain the perovskite film.

[0014] In one or more embodiments, the coating is carried out by spin coating, knife coating or continuous coating.

[0015] In one or more embodiments, the annealing temperature is 80-150°C.

[0016] In one or more embodiments, the annealing time is 10-60 min.

[0017] The invention provides a perovskite film prepared by the method described in the invention.

[0018] In one or more embodiments, the perovskite film has a thickness of 100-1200 nm.

[0019] In one or more embodiments, the perovskite film comprises a perovskite structure material, and the chemical formula of the perovskite structure material is ABX3.

[0020] The present invention provides a perovskite solar cell comprising the perovskite film of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Scanning electron microscope images (SEM) of the perovskite films prepared in Example 1 of the present invention (Figure (a)) and Comparative Example 1 (Figure (b)).

[0022] Figure 2 Atomic force microscope (AFM) images of the perovskite films prepared in Example 1 of the present invention (Figure (a)) and Comparative Example 1 (Figure (b)).

[0023] Figure 3 The X-ray diffraction patterns (XRD) of the perovskite films prepared in Example 1 and Comparative Example 1 of the present invention.

[0024] Figure 4 The open circuit voltage, short circuit current density, fill factor and energy conversion efficiency of the perovskite solar cells prepared in Example 2, Example 3 and Comparative Example 2 of the present invention.

[0025] Figure 5 It is a histogram of the energy conversion efficiency of the perovskite solar cells prepared in Example 2 of the present invention and Comparative Example 2. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0027] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0028] Herein, “comprising”, “including”, “containing” and similar terms encompass the meanings of “consisting essentially of” and “consisting of”. For example, when “A comprises B and C” is disclosed herein, “A consists essentially of B and C” and “A consists of B and C” should be deemed to be disclosed herein.

[0029] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0030] In this document, unless otherwise specified, percentage refers to mass percentage and ratio refers to mass ratio.

[0031] Herein, when describing embodiments or examples, it should be understood that they are not used to limit the present invention to these embodiments or examples. On the contrary, all substitutes, improvements and equivalents of the methods and materials described in the present invention can be included in the scope limited by the claims.

[0032] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0033] The present invention provides a perovskite precursor solution, and the solvent of the perovskite precursor solution may include N, N-dimethylformamide and tetramethylurea. In the present invention, the combination of N, N-dimethylformamide and tetramethylurea is used as the solvent of the perovskite precursor solution, which is beneficial to improving the quality of the perovskite film, and then the open circuit voltage and energy conversion efficiency of the perovskite solar cell.

[0034] In the solvent of the perovskite precursor solution of the present invention, the volume ratio of N,N-dimethylformamide and tetramethylurea (TMU) can be (3-20): 1, for example 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 9: 1, 10: 1, 11: 1, 12: 1, 13: 1, 14: 1, 15: 1, 16: 1, 17: 1, 18: 1, 19: 1, 20: 1. In the present invention, controlling the volume ratio of N,N-dimethylformamide and tetramethylurea within the above range is beneficial to improving the open circuit voltage of the perovskite solar cell. In the solvent of the perovskite precursor solution of the present invention, the volume ratio of N, N-dimethylformamide and tetramethylurea can be preferably (8-20): 1, such as 8: 1, 9: 1, 10: 1, 11: 1, 12: 1, 13: 1, 14: 1, 15: 1, 16: 1, 17: 1, 18: 1, 19: 1, 20: 1. In the present invention, the volume ratio of N, N-dimethylformamide and tetramethylurea is controlled within the above-mentioned preferred range, which is conducive to improving the open circuit voltage of the perovskite solar cell while maintaining the energy conversion efficiency. In the solvent of the perovskite precursor solution of the present invention, the volume ratio of N, N-dimethylformamide and tetramethylurea can be more preferably (16-20): 1, such as 16: 1, 17: 1, 18: 1, 19: 1, 20: 1. In the present invention, controlling the volume ratio of N,N-dimethylformamide to tetramethylurea within the above preferred range is beneficial to simultaneously improving the open circuit voltage and energy conversion efficiency of the perovskite solar cell.

[0035] In the present invention, the solvent of the perovskite precursor solution may also include dimethyl sulfoxide. In the present invention, the use of a combination of N,N-dimethylformamide, dimethyl sulfoxide and tetramethyl urea as the solvent of the perovskite precursor solution is beneficial to improving the quality of the perovskite film, and thus the open circuit voltage and energy conversion efficiency of the perovskite solar cell.

[0036] In the present invention, the volume ratio of dimethyl sulfoxide to N,N-dimethylformamide can be (0.001-0.5): 1, for example, 0.05: 1, 0.1: 1, 0.15: 1, 0.25: 1, 0.3: 1, 0.35: 1, 0.4: 1, 0.45: 1, 0.5: 1. In the present invention, controlling the volume ratio of N,N-dimethylformamide to tetramethyl urea within the above preferred range is beneficial to improving the open circuit voltage of the perovskite solar cell.

[0037] In the present invention, the raw materials of the perovskite precursor solution may include a first precursor compound and a second precursor compound of a perovskite structure material, the chemical formula of the first precursor compound may be AX, and the chemical formula of the second precursor compound may be BX2; wherein the A ion may be one or more selected from formamidine ions, cesium ions, methylamine ions, dimethylamine ions, guanidine ions, potassium ions and rubidium ions, the B ions may be lead ions and / or tin ions, and the X ions may be one or more selected from bromide ions, iodide ions, chloride ions, thiocyanate ions and fluoroborate ions.

[0038] In the present invention, the concentration of B ions in the perovskite precursor solution can be 1-2 mol / L, for example, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2.0 mol / L.

[0039] The method for preparing a perovskite film of the present invention comprises: coating the perovskite precursor solution of the present invention, and then annealing to obtain the perovskite film.

[0040] In the present invention, the coating method can be spin coating, blade coating or continuous coating. In some embodiments, the spin coating method uses a spin coater; in some embodiments, the blade coating method uses air blowing assistance.

[0041] In the present invention, the annealing temperature may be 80-150°C, for example, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C.

[0042] In the present invention, the annealing time can be 10-60 min, for example, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min.

[0043] In the present invention, the thickness of the perovskite film can be 100-1200nm, for example, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, 1100nm, 1200nm.

[0044] The present invention provides a perovskite solar cell comprising the perovskite film of the present invention. In the present invention, the perovskite solar cell may include a formal perovskite solar cell or an inverted perovskite solar cell. In the present invention, the formal perovskite solar cell may include an electron transport layer, a perovskite film and a hole transport layer in sequence. In the present invention, the inverted perovskite solar cell may include a hole transport layer, a perovskite film and an electron transport layer in sequence.

[0045] In the present invention, the hole transport layer can be one or more of nickel oxide, PTAA, PEDOT and self-assembled monomolecular materials (SAMs).

[0046] In the present invention, the thickness of the hole transport layer can be 5-100 nm, for example, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm.

[0047] In the present invention, the electron transport layer may be one or more of C60 and its structural derivatives, tin oxide and titanium dioxide.

[0048] In the present invention, the thickness of the electron transport layer can be 10-200nm, for example, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 120nm, 140nm, 160nm, 180nm, 200nm. In the present invention, the perovskite solar cell can include a single-junction perovskite solar cell or a stacked perovskite solar cell.

[0049] In the present invention, the stacked perovskite solar cell further comprises a second light absorbing layer, and the material of the second light absorbing layer may be Si, GaAs, CdTe, CIGS or a perovskite structured material.

[0050] In the present invention, the formal perovskite solar cell may include a formal tandem perovskite solar cell or a formal single-junction perovskite solar cell.

[0051] In the present invention, the inverted perovskite solar cell may include an inverted tandem perovskite solar cell or an inverted single-junction perovskite solar cell.

[0052] In some embodiments, a formal single-junction perovskite solar cell includes, in sequence, a conductive substrate, an electron transport layer, a perovskite thin film, a hole transport layer, and a back electrode.

[0053] In some embodiments, an inverted single-junction perovskite solar cell comprises, in sequence, a conductive substrate, a hole transport layer, a perovskite film, an electron transport layer, and a back electrode. The present invention provides a method for preparing a formal perovskite solar cell, the method comprising the following steps: (1) depositing a perovskite film layer on the surface of the electron transport layer, and depositing a hole transport layer on the surface of the perovskite film layer.

[0054] The present invention provides a method for preparing an inverse perovskite solar cell, the method comprising the following steps: (1') depositing a perovskite film layer on the surface of a hole transport layer, and depositing an electron transport layer on the surface of the perovskite film layer.

[0055] In the present invention, the hole transport layer can be deposited by spin coating, blade coating or thermal evaporation.

[0056] In the present invention, the electron transport layer can be deposited by spin coating, scraper coating or thermal evaporation.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] 1. In the present invention, tetramethyl urea slows down the crystallization rate, increases the final perovskite grain size, significantly improves the open circuit voltage of the final device, and significantly improves the overall energy conversion efficiency;

[0059] 2. In the present invention, tetramethyl urea has lower toxicity than DMSO and DMF, is more environmentally friendly, and is suitable for large-scale production;

[0060] 3. In the present invention, the cost of tetramethyl urea is lower than that of DMF and DMSO.

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

[0062] Example 1

[0063] This example prepares the perovskite film according to the following steps:

[0064] The raw materials and solvent of the perovskite precursor solution were mixed to prepare a perovskite precursor solution with a lead ion concentration of 1.5 mol / L, wherein the solvent was DMF, DMSO and TMU, and the volume ratio of DMF, DMSO and TMU was 4:0.75:0.25. The perovskite precursor solution was deposited on the surface of the ITO conductive glass by spin coating, and then annealed at 100°C for 10 minutes to obtain a material of FA 0.8 Cs 0.2 Pb(I 0.7 Br 0.3 )3. Perovskite film with a thickness of 500nm.

[0065] Comparative Example 1

[0066] The other conditions of this comparative example are the same as those of Example 1, except that the solvent in this comparative example does not contain TMU, and the volume ratio of DMF to DMSO is 4:1.

[0067] Test Example 1

[0068] The perovskite films prepared in Example 1 and Comparative Example 1 were subjected to scanning electron microscopy, atomic force microscopy and X-ray diffraction tests.

[0069] Figure 1 The following are scanning electron microscope images (SEM) of the perovskite films prepared in Example 1 (Figure (a)) of the present invention and Comparative Example 1 (Figure (b)). Figure 1 It can be seen that the perovskite film prepared in Example 1 with TMU added as a solvent component is smoother and denser than the perovskite film prepared in Comparative Example 1.

[0070] Figure 2 Atomic force microscope (AFM) images of the perovskite film prepared in Example 1 (Figure (a)) of the present invention and Comparative Example 1 (Figure (b)). Figure 2 It can be seen that the surface undulation of the perovskite film obtained in Example 1 is smaller, characterized by the root mean square height (rms), rms of Example 1 = 15.01 nm, and rms of Comparative Example 1 = 23.04 nm.

[0071] Figure 3 The X-ray diffraction patterns (XRD) of the perovskite films prepared in Example 1 and Comparative Example 1 of the present invention are shown in FIG. Figure 3 It can be seen that by analyzing the relative intensity of the perovskite peak, it is shown that Example 1 has better crystallinity, and through the relative intensity comparison of (001) and (011) (14.2° and 19.94° respectively), it can be seen that the crystal orientation of Example 1 has changed, with the (001) plane being the main one, and this structure is more conducive to the transport of carriers.

[0072] Example 2

[0073] This embodiment prepares a perovskite solar cell according to the following steps:

[0074] (1) Cleaning the ITO substrate and irradiating it with UV for 15 minutes to obtain a clean conductive substrate;

[0075] (2) spin coating a 10 mg / mL nickel oxide solution (the solvent is deionized water) dispersion on a clean conductive substrate and drying to obtain a hole transport layer with a thickness of 15 nm;

[0076] (3) The raw materials of the perovskite precursor solution and the solvent are mixed to prepare a perovskite precursor solution with a lead ion concentration of 1.5 mol / L, wherein the solvent is DMF, DMSO and TMU, and the volume ratio of DMF, DMSO and TMU is 4:0.75:0.25. The perovskite precursor solution is deposited on the surface of the hole transport layer by spin coating, and then annealed at 100° C. for 10 minutes to obtain a material of FA 0.8 Cs 0.2 Pb(I 0.7 Br 0.3 )3. Perovskite film with a thickness of 500nm;

[0077] (4) preparing an electron transport layer made of C60 and having a thickness of 26 nm by thermal evaporation;

[0078] (5) A metal electrode made of Cu and with a thickness of 150 nm was prepared by thermal evaporation.

[0079] Example 3

[0080] The other conditions of this embodiment are the same as those of embodiment 2, except that the volume ratio of DMF, DMSO and TMU in this embodiment is 4:0.8:0.2.

[0081] Example 4

[0082] The other conditions of this embodiment are the same as those of embodiment 2, except that the volume ratio of DMF, DMSO and TMU is 3:1:1 in this embodiment.

[0083] Example 5

[0084] The other conditions of this embodiment are the same as those of embodiment 2, except that the volume ratio of DMF, DMSO and TMU is 4:0.5:0.5 in this embodiment.

[0085] Example 6

[0086] The other conditions of this embodiment are the same as those of embodiment 2, except that the volume ratio of DMF, DMSO and TMU in this embodiment is 4:0.25:0.75.

[0087] Example 7

[0088] The other conditions of this example are the same as those of Example 2, except that the solvent in this example does not contain DMSO, and the volume ratio of DMF to TMU is 4:1.

[0089] Comparative Example 2

[0090] The other conditions of this comparative example are the same as those of Example 2, except that the solvent in this comparative example does not contain TMU, and the volume ratio of DMF to DMSO is 4:1.

[0091] Comparative Example 3

[0092] The other conditions of this comparative example are the same as those of Example 2, except that TMU is replaced by dimethoxyethanol in this comparative example.

[0093] Comparative Example 4

[0094] The other conditions of this comparative example are the same as those of Example 2, except that TMU is replaced by N,N-dimethylpropylene urea in this comparative example.

[0095] Comparative Example 5

[0096] The other conditions of this comparative example are the same as those of Example 2, except that the volume ratio of DMF, DMSO and TMU in this comparative example is 1:1:1.

[0097] Comparative Example 6

[0098] The other conditions of this comparative example are the same as those of Example 2, except that in this comparative example, DMF and DMSO are used as solvents in a volume ratio of 4:0.75, and TMU as a solvent is replaced by hydantoin as a solid additive, wherein the concentration of hydantoin is 1 mg / mL.

[0099] Test Example 2

[0100] Device performance test of perovskite solar cells: Under the AM 1.5G standard solar spectrum, a solar simulator was used to set the voltage range to -0.1 to 1.3 V, and the current output of the perovskite solar cells prepared in Examples 2-7 and Comparative Examples 2-6 at different voltages was tested, and the corresponding current-voltage (IV) characteristic curves were plotted, where the cell surface area was 1.044 cm 2 , the incident light power (Pin) is 100mW / cm 2 The open circuit voltage, short circuit current density, fill factor and energy conversion efficiency of Examples 2-7 and Comparative Examples 2-6 were obtained according to the characteristic curves.

[0101] (1) Open circuit voltage (Voc): The voltage value corresponding to when the current is equal to zero.

[0102] (2) Short-circuit current density (Jsc): The current value when the voltage is zero is the short-circuit current (Isc), and the current per unit battery surface area is the short-circuit current density.

[0103] (3) Fill factor (FF): The ratio of the maximum output power (Pmax) of the battery to the product of the open circuit voltage and the short circuit current. The calculation formula is (Pmax / Voc*Isc), where the maximum power point is the point where the battery output power reaches its maximum value.

[0104] (4) Power conversion efficiency (PCE): Power conversion efficiency refers to the ratio of maximum output power to incident light power (Pin), and the calculation formula is (Pmax / Pin)*100%.

[0105] The test results of the open circuit voltage, short circuit current density, fill factor and energy conversion efficiency of the perovskite solar cells prepared in Examples 2-7 and Comparative Examples 2-6 are shown in Table 1.

[0106] Table 1: Open circuit voltage, short circuit current density, fill factor and energy conversion efficiency of perovskite solar cells prepared in Examples 2-7 and Comparative Examples 2-6

[0107] Voc(V) PCE(%) FF(%) <![CDATA[Jsc(mA / cm 2 )]]> Example 2 1.28527 21.47703 80.24064 20.82502 Example 3 1.27337 22.06196 82.72397 20.944 Example 4 1.2635 18.95063 76.75698 19.54033 Example 5 1.26742 20.85613 80.15382 20.53912 Example 6 1.24861 19.03261 79.24837 19.23444 Example 7 1.24933 20.93875 79.91224 20.97298 Comparative Example 2 1.23823 20.22574 78.17921 20.89356 Comparative Example 3 1.20256 18.24884 73.05709 20.77151 Comparative Example 4 1.17507 17.06626 76.609 18.95802 Comparative Example 5 1.14598 15.02992 69.16659 18.96204 Comparative Example 6 1.2239 20.91367 82.3703 20.74493

Claims

1. A perovskite precursor solution, characterized in that: The solvent of the perovskite precursor solution includes N,N-dimethylformamide and tetramethyl urea in a volume ratio of (3-20):

1.

2. The perovskite precursor solution according to claim 1, characterized in that In the solvent of the perovskite precursor solution, the volume ratio of N,N-dimethylformamide to tetramethylurea is (8-20):

1.

3. The perovskite precursor solution according to claim 1, characterized in that In the solvent of the perovskite precursor solution, the volume ratio of N,N-dimethylformamide to tetramethylurea is (16-20):

1.

4. The perovskite precursor solution according to claim 1, characterized in that The solvent of the perovskite precursor solution further includes dimethyl sulfoxide; and / or The raw materials of the perovskite precursor solution include a first precursor compound and a second precursor compound of a perovskite structure material, the chemical formula of the first precursor compound is AX, and the chemical formula of the second precursor compound is BX2; wherein the A ion is selected from one or more of formamidinium ion, cesium ion, methylamine ion, dimethylamine ion, guanidine ion, potassium ion and rubidium ion, the B ion is lead ion and / or tin ion, and the X ion is selected from one or more of bromide ion, iodide ion, chloride ion, thiocyanate ion and fluoroborate ion; the concentration of the B ion in the perovskite precursor solution is 1-2 mol / L.

5. The perovskite precursor solution according to claim 4, characterized in that The volume ratio of dimethyl sulfoxide to N,N-dimethylformamide is (0.001-0.5):

1.

6. A method for preparing a perovskite film, characterized in that: The method comprises coating the perovskite precursor solution according to any one of claims 1 to 5, and then annealing to obtain a perovskite film.

7. The method according to claim 6, characterized in that The method has one or more of the following features: The coating method is spin coating, blade coating or continuous coating; The annealing temperature is 80-150°C; The annealing time is 10-60 min.

8. A perovskite film prepared by the method of claim 6 or 7.

9. The perovskite film according to claim 8, characterized in that The thickness of the perovskite film is 100-1200 nm; and / or The perovskite film contains a perovskite structure material, and the chemical formula of the perovskite structure material is ABX3.

10. A perovskite solar cell, characterized in that: The perovskite solar cell comprises the perovskite thin film according to claim 8 or 9.

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