Broadband-gap perovskite thin film and preparation method and application thereof

Abstract

The invention discloses a wide-band-gap perovskite thin film and a preparation method and application thereof, and relates to the technical field of solar cells, and the method sequentially comprises the following steps: coating a glass substrate with an ethanol solution of (4-(7H-dibenzo [c, g] carbazole-7-yl) butyl) phosphonic acid, and then annealing to prepare a glass substrate / 4PADCB; the preparation method comprises the following steps: preparing a precursor solution, then coating a broadband gap mixed perovskite precursor solution, dropwise adding an anti-solvent diethyl carbonate in the coating process, then annealing, and then coating a 1, 3-diaminopropane dihydriodate post-treatment solution to prepare the broadband gap perovskite thin film. The doping of [bis (trifluoroacetoxy) iodine] benzene (BTFIB) can improve the quality of the wide-band gap perovskite thin film, reduce the defect state density of the thin film, prolong the service life of current carriers, and finally improve the photoelectric conversion efficiency of the cell.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and particularly relates to a wide-bandgap perovskite thin film, a preparation method thereof, and an application thereof. Background Art

[0002] Perovskite solar cells have attracted extensive attention in the academic and industrial fields due to their advantages such as adjustable bandgap, high light absorption coefficient, and high carrier mobility. The power conversion efficiency of single-junction perovskite solar cells has been increased from 3.8% in 2009 to 27% today, approaching the highest conversion efficiency of crystalline silicon solar cells. A top cell based on a wide-bandgap perovskite light-absorbing material combined with a crystalline silicon solar bottom cell can construct a perovskite / crystalline silicon tandem solar cell, thereby obtaining a power conversion efficiency exceeding the Shockley-Queisser limit and being expected to be extended to flexible and lightweight optoelectronic applications.

[0003] As an important part of perovskite / crystalline silicon tandem solar cells, the performance of wide-bandgap perovskite solar cells is crucial for the development of perovskite / crystalline silicon tandem solar cells. At present, although wide-bandgap perovskite solar cells have achieved a certified efficiency of more than 23%, they are still lower than the efficiency of crystalline silicon solar cells. Their further development space is mainly limited by photoinduced phase separation and uncontrolled rapid crystallization during the film formation process, which result in a high density of defect states in the perovskite thin film. Additive engineering has been widely used to regulate the film crystallization process and passivate related defects, thereby reducing the non-radiative recombination of carriers in the perovskite thin film and improving the power conversion efficiency of wide-bandgap perovskite solar cells; in addition, higher-quality films and lower defect state density also contribute to the improvement of device stability. Therefore, a functional additive with multiple functional groups is particularly important for realizing highly efficient and stable wide-bandgap perovskite solar cells. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a wide-bandgap perovskite thin film, a preparation method thereof, and an application thereof, so as to solve the problems of poor power conversion efficiency and stability of existing wide-bandgap perovskite solar cells.

[0005] The technical solution of the present invention for solving the above technical problems is as follows: providing a preparation method of a wide-bandgap perovskite thin film, which sequentially includes the following steps: (1) Preparation of the hole transport layer: Coating an ethanol solution of (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid on a glass substrate, and then annealing to obtain a glass substrate / 4PADCB; (2)Preparation of perovskite light-absorbing layer: On the glass substrate / 4PADCB obtained in step (1), a wide-bandgap hybrid perovskite precursor solution is coated. During the coating process, diethyl carbonate as an anti-solvent is added dropwise, and then annealing is carried out. After that, a post-treatment solution of 1,3-diaminopropane dihydroiodide is coated to obtain a wide-bandgap perovskite thin film.

[0006] Based on the above technical solutions, the present invention can be further improved as follows: Further, in step (1), the glass substrate is pretreated before coating. The pretreatment process includes the following steps: first, rinse with deionized water containing a cleaning agent, then ultrasonically clean with deionized water and ethanol for 20 - 30 min each in sequence, then dry with nitrogen, and finally treat under ultraviolet and ozone conditions for 15 - 20 min.

[0007] Further, the cleaning agent is DECON90 cleaning agent.

[0008] Further, in step (1), the glass substrate is an indium tin oxide glass substrate or a borosilicate glass substrate.

[0009] Further, in step (1), the concentration of the ethanol solution of (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid is 0.3 - 0.8 mg / mL.

[0010] Further, in step (1), the concentration of the ethanol solution of (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid is 0.5 mg / mL.

[0011] Further, in step (1), the coating method is spin coating, the spin coating speed is 3000 - 4000 rpm, the acceleration is 3000 - 10000 rpm / s, and the spin coating time is 20 - 30 s.

[0012] Further, in step (1), the annealing temperature is 100 - 120 °C, and the annealing time is 10 - 15 min.

[0013] Further, in step (2), the wide-bandgap hybrid perovskite precursor solution is prepared through the following steps: in a nitrogen environment, to the perovskite of FA 0.8 Cs 0.15 MA 0.05 PbI 2.4 Br 0.6 add Pb(SCN)2, then add [bis(trifluoroacetoxy)iodo]benzene to obtain a mixture, and then dissolve the mixture in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide, and stir to prepare it.

[0014] Further, the molar amount of Pb(SCN)2 is the perovskite component Pb 2+0.8 - 1.2% of the molar amount.

[0015] Further, the molar amount of Pb(SCN)₂ is 1% of the perovskite component Pb 2+ 1% of the molar amount.

[0016] Further, the molar amount of [bis(trifluoroacetoxy)iodo]benzene is 0.8 - 1.2% of the perovskite component Pb 2+ 0.8 - 1.2% of the molar amount.

[0017] Further, the molar amount of [bis(trifluoroacetoxy)iodo]benzene is 1% of the perovskite component Pb 2+ 1% of the molar amount.

[0018] Further, the volume ratio of N,N - dimethylformamide to dimethyl sulfoxide is 3 - 5:1.

[0019] Further, the volume ratio of N,N - dimethylformamide to dimethyl sulfoxide is 4:1.

[0020] Further, the solid - liquid ratio during dissolution is 800 - 900 mg:1 mL.

[0021] Further, the solid - liquid ratio during dissolution is 873.06 mg:1 mL.

[0022] Further, stir for 4 - 8 h under a nitrogen atmosphere.

[0023] Further, in step (2), the coating method of the wide - bandgap perovskite precursor solution is spin - coating, the spin - coating speed is 3000 - 5000 rpm, and the spin - coating time is 40 - 60 s.

[0024] Further, in step (2), diethyl carbonate as an antisolvent is added dropwise at 20 - 30 s after the start of coating.

[0025] Further, in step (2), the annealing temperature is 60 - 100 °C and the annealing time is 2 - 15 min.

[0026] Further, in step (2), the 1,3 - diaminopropane dihydroiodide post - treatment solution is prepared by the following method: mix isopropanol and chlorobenzene to obtain a mixed solvent, mix the mixed solvent and 1,3 - diaminopropane dihydroiodide at a liquid - to - material ratio of 5 mL:5 - 10 mg, and stir for 4 - 8 h under a nitrogen atmosphere to obtain it.

[0027] Further, the volume ratio of isopropanol to chlorobenzene is 1:1.

[0028] Further, in step (2), the coating method of the 1,3 - diaminopropane dihydroiodide post - treatment solution is spin - coating, the spin - coating speed is 3000 - 5000 rpm, and the spin - coating time is 30 - 40 s.

[0029] The present invention also provides a wide-bandgap perovskite thin film prepared by the preparation method of the above wide-bandgap perovskite thin film.

[0030] The present invention also provides the application of the above wide-bandgap perovskite thin film in the preparation of a solar cell. Furthermore, the preparation method of the solar cell includes the following steps: placing the wide-bandgap perovskite thin film in a vacuum, and then sequentially depositing 18-22 nm of fullerene, 4-7 nm of bathocuproine, and 90-150 nm of metallic copper, thus obtaining the solar cell.

[0031] Furthermore, the deposition method is thermal evaporation.

[0032] The present invention has the following beneficial effects: The wide-bandgap (1.67 eV) perovskite thin film of the present application is prepared by adding a multi-functional organic material to a perovskite precursor solution. The multi-functional organic material contains three groups: trifluoroacetoxy group, hypervalent iodine, and benzene ring. The doping of [bis(trifluoroacetoxy)iodo]benzene (BTFIB) can improve the quality of the wide-bandgap perovskite thin film, reduce the density of defect states of the thin film, increase the carrier lifetime, and ultimately improve the photoelectric conversion efficiency of the battery. Description of the Drawings

[0033] Figure 1 is the structural formula of the additive BTFIB of the present invention; Figure 2 is a schematic structural diagram of the wide-bandgap perovskite solar cell prepared by the present invention; Figure 3 is the SEM image of the perovskite thin film prepared in Comparative Example 1; Figure 4 is the SEM image of the wide-bandgap perovskite thin film prepared in Example 1; Figure 5 is the XRD pattern of the perovskite thin films prepared in Example 1 and Comparative Example 1; Figure 6 is the TRPL pattern of the perovskite thin films prepared in Example 4 and Comparative Example 2; Figure 7 is the current density-voltage characteristic curve of the solar cells made of the perovskite thin films prepared in Example 1 and Comparative Example 1; Figure 8 is the decay diagram of the conversion efficiency of the solar cells made of the perovskite thin films prepared in Example 1 and Comparative Example 1 with storage time. Detailed Embodiments

[0034] The principles and features of the present invention will be described below in conjunction with the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. For those conditions not specified in the examples, they shall be carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0035] The structural formula of bis(trifluoroacetoxy)iodo]benzene (BTFIB) is shown in Figure 1 .

[0036] Example 1: A wide-bandgap perovskite film, and its preparation method includes the following steps: (1) Preparation of the wide-bandgap hybrid perovskite precursor solution: In a nitrogen environment, to the perovskite of FA 0.8 Cs 0.15 MA 0.05 PbI 2.4 Br 0.6 by molar ratio, add the additive Pb(SCN)2 (the molar amount thereof is 1% of the molar amount of the perovskite component Pb 2+ ), and then add bis(trifluoroacetoxy)iodo]benzene (BTFIB, the molar amount thereof is 1% of the molar amount of the perovskite component Pb 2+ ) to obtain a mixture. Then dissolve the mixture in a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) (the volume ratio of DMF to DMSO is 4:1), and finally stir for 4 h in a nitrogen environment to obtain it; (2) Preparation of the 1,3-diaminopropane dihydroiodide post-treatment solution: Mix 2.5 mL of isopropanol and 2.5 mL of chlorobenzene to obtain a mixed solvent. Mix the mixed solvent and 1,3-diaminopropane dihydroiodide according to a liquid-to-material ratio of 5 mL:5 mg, and stir for 4 h in a nitrogen environment to obtain it (3) Pretreatment of the glass substrate: First, rinse the ITO glass with a size of 2.5 cm × 2.5 cm with deionized water containing DECON90 cleaning agent, then ultrasonically clean with deionized water and ethanol for 30 min each, then dry with dry nitrogen, and finally place it in an ultraviolet-ozone cleaning machine for 15 min to obtain a pretreated glass substrate; (4) Preparation of the hole transport layer: Coat an ethanol solution of (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid (concentration: 0.5 mg / mL) on the pretreated glass substrate prepared in step (1), using spin coating, the spin coating speed is 3000 rpm, the acceleration is 3000 rpm / s, the spin coating time is 20 s, and then anneal, the annealing temperature is 100 °C, and the annealing time is 10 min to obtain the glass substrate / 4PADCB; (5) Preparation of the perovskite light-absorbing layer: In a glove box, on the 4PADCB layer of the glass substrate / 4PADCB prepared in step (4), the broadband-gap hybrid perovskite precursor solution prepared in step (1) was spin-coated at a rotational speed of 4000 rpm for 40 s. Diethyl carbonate (DEC) as an anti-solvent was added dropwise 20 s after the start of coating, and then annealed on a hot plate at an annealing temperature of 100 °C for 10 min. Then, the post-treatment solution of 1,3-diaminopropane dihydroiodide prepared in step (2) was spin-coated on the perovskite film at a rotational speed of 3000 rpm for 30 s to obtain a broadband-gap perovskite film.

[0037] A solar cell, the preparation method thereof comprising the following steps: Transfer the ITO glass substrate / 4PADCB / perovskite (the broadband-gap perovskite film prepared in step (5)) to a vacuum chamber, and successively deposit 20 nm of fullerene (C 60 )、5 nm of bathocuproine (BCP) and 100 nm of Cu by thermal evaporation on the perovskite film, thereby completing the preparation of the broadband-gap perovskite solar cell (see Figure 2 ).

[0038] Example 2: A broadband-gap perovskite film, the preparation method thereof comprising the following steps: (1) Preparation of the broadband-gap hybrid perovskite precursor solution: In a nitrogen environment, to the perovskite of FA 0.8 Cs 0.15 MA 0.05 PbI 2.4 Br 0.6 weighed according to the molar ratio, add the additive Pb(SCN)2 (the molar amount thereof is 0.8% of the molar amount of the perovskite component Pb 2+ ), and then add [bis(trifluoroacetoxy)iodo]benzene (BTFIB, the molar amount thereof is 0.8% of the molar amount of the perovskite component Pb 2+ ) to obtain a mixture, and then dissolve the mixture in a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) (the volume ratio of DMF to DMSO is 3:1), and finally stir for 5 h in a nitrogen environment to obtain; (2) Preparation of the 1,3-diaminopropane dihydroiodide post-treatment solution: Mix 2.5 mL of isopropanol and 2.5 mL of chlorobenzene to obtain a mixed solvent, and mix the mixed solvent and 1,3-diaminopropane dihydroiodide according to a liquid-to-material ratio of 5 mL:8 mg, and stir for 5 h in a nitrogen environment to obtain (3) Pretreatment of the glass substrate: The ITO glass with a size of 2.5 cm × 2.5 cm was first rinsed with deionized water containing DECON90 cleaning agent, then ultrasonically treated with deionized water and ethanol for 25 min each in sequence, dried with dry nitrogen, and finally placed in an ultraviolet-ozone cleaning machine for 18 min to obtain the pretreated glass substrate; (4) Preparation of the hole transport layer: An ethanol solution of (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid (concentration: 0.3 mg / mL) was spin-coated on the pretreated glass substrate obtained in step (1) at a spin-coating speed of 3500 rpm, an acceleration of 6000 rpm / s, and a spin-coating time of 25 s, and then annealed at an annealing temperature of 110 °C for 12 min to obtain the glass substrate / 4PADCB; (5) Preparation of the perovskite light-absorbing layer: In the glove box, on the 4PADCB layer of the glass substrate / 4PADCB obtained in step (4), the wide-bandgap hybrid perovskite precursor solution prepared in step (1) was spin-coated at a spin-coating speed of 3000 rpm and a spin-coating time of 50 s. Diethyl carbonate (DEC) as an anti-solvent was added dropwise at the 25th s after the start of coating, and then annealed on a hot plate at an annealing temperature of 80 °C for 2 min. Then, the post-treatment solution of 1,3-diaminopropane dihydroiodide prepared in step (2) was spin-coated on the perovskite film at a spin-coating speed of 4000 rpm and a spin-coating time of 35 s to obtain the wide-bandgap perovskite film.

[0039] A solar cell, and its preparation method includes the following steps: Transfer the ITO glass substrate / 4PADCB / perovskite (the wide-bandgap perovskite film prepared in step (5)) to a vacuum chamber, and by means of thermal evaporation, deposit 18 nm of fullerene (C 60 )、4 nm of bathocuproine (BCP) and 90 nm of Cu on the perovskite film in sequence, thereby completing the preparation of the wide-bandgap perovskite solar cell (see Figure 2 ).

[0040] Example 3: A preparation method of a wide-bandgap perovskite film includes the following steps: (1) Preparation of the wide-bandgap hybrid perovskite precursor solution: In a nitrogen environment, to the perovskite of FA 0.8 Cs 0.15 MA 0.05 PbI 2.4 Br 0.6 weighed according to the molar ratio, add the additive Pb(SCN)2 (the molar amount thereof is the perovskite component Pb 2+1.2% of the molar amount), and then add bis(trifluoroacetoxy)iodobenzene (BTFIB, with a molar amount of the perovskite component Pb 2+ 1.2% of the molar amount) to obtain a mixture, and then dissolve the mixture in a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) (the volume ratio of DMF to DMSO is 5:1), and finally stir for 8 h under a nitrogen atmosphere to prepare it; (2) Preparation of 1,3-diaminopropane dihydroiodide post-treatment solution: Mix 2.5 mL of isopropanol and 2.5 mL of chlorobenzene to obtain a mixed solvent, and mix the mixed solvent and 1,3-diaminopropane dihydroiodide at a liquid-to-material ratio of 5 mL:10 mg, and stir for 8 h under a nitrogen atmosphere to prepare it (3) Pretreatment of glass substrate: First, rinse the ITO glass with a size of 2.5 cm × 2.5 cm with deionized water containing DECON90 cleaning agent, then ultrasonically clean with deionized water and ethanol for 20 min each, then dry with dry nitrogen, and finally place it in an ultraviolet-ozone cleaning machine for 20 min to obtain a pretreated glass substrate; (4) Preparation of hole transport layer: Coat an ethanol solution of (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid (concentration: 0.8 mg / mL) on the pretreated glass substrate prepared in step (1), and use spin coating with a spin coating speed of 4000 rpm, an acceleration of 10000 rpm / s, and a spin coating time of 30 s, and then anneal at an annealing temperature of 120 °C for 15 min to obtain glass substrate / 4PADCB; (5) Preparation of perovskite light-absorbing layer: In a glove box, coat the broadband-gap perovskite precursor solution prepared in step (1) on the 4PADCB layer of the glass substrate / 4PADCB prepared in step (4), and use spin coating with a spin coating speed of 5000 rpm and a spin coating time of 60 s. Drop the antisolvent diethyl carbonate (DEC) at the 30th second after the start of coating, and then anneal on a hot stage at an annealing temperature of 60 °C for 15 min. Then coat the 1,3-diaminopropane dihydroiodide post-treatment solution prepared in step (2) on the perovskite thin film, and use spin coating with a spin coating speed of 5000 rpm and a spin coating time of 40 s to obtain a broadband-gap perovskite thin film.

[0041] A solar cell, and its preparation method includes the following steps: Transfer the ITO glass substrate / 4PADCB / perovskite (the broadband-gap perovskite thin film prepared in step (5)) to a vacuum chamber, and use thermal evaporation to sequentially deposit 22 nm of fullerene (C 60 )、7 nm of bathocuproine (BCP) and 150 nm of Cu on the perovskite thin film, thereby completing the preparation of the broadband-gap perovskite solar cell (seeFigure 2 ).

[0042] Example 4: A wide-bandgap perovskite thin film, and its preparation method includes the following steps: In step (3), the glass substrate is a borosilicate glass substrate, and the rest is the same as in Example 1.

[0043] Comparative Example 1: A perovskite thin film, and its preparation method includes the following steps: In step (1), bis(trifluoroacetoxy)iodobenzene (BTFIB) is not added, and the rest is the same as in Example 1.

[0044] Comparative Example 2: A perovskite thin film, and its preparation method includes the following steps: In step (3), the glass substrate is a borosilicate glass substrate, and the rest is the same as in Comparative Example 1.

[0045] Test Example I. The perovskite thin films prepared in Comparative Example 1 and Example 1 were subjected to SEM (scanning electron microscope) detection. In order to ensure that the detection was not blocked, the products without coating the 1,3-diaminopropane dihydroiodide post-treatment solution in step (5) were used for detection. The results are shown in Figures 3-4 .

[0046] It can be seen from Figures 3-4 that there are other phases in the grains of the untreated perovskite thin film, and this phase may be PbI2. The PbI2 on the surface of the BTFIB-doped perovskite thin film disappears, II. The perovskite thin films prepared in Example 1 and Comparative Example 1 were subjected to XRD (X-ray diffraction) detection. In order to ensure that the detection was not blocked, the products without coating the 1,3-diaminopropane dihydroiodide post-treatment solution in step (5) were used for detection. The results are shown in Figure 5 .

[0047] It can be seen from Figure 5 that the BTFIB-doped perovskite thin film in Example 1 exhibits higher intensity, indicating that the perovskite thin film treated with BTFIB has better crystallinity. In summary, the perovskite thin film treated with BTFIB in this application has better film quality.

[0048] III. The perovskite thin films prepared in Example 4 and Comparative Example 2 were subjected to TRPL (time-resolved photoluminescence) testing. In order to ensure that the detection was not blocked, the products without coating the 1,3-diaminopropane dihydroiodide post-treatment solution in step (5) were used for detection. The results are shown in Figure 6 .

[0049] It can be seen from Figure 6It can be seen that the carrier lifetime in the perovskite film doped with BTFIB in Example 4 exceeds 1.4 μs, which is much higher than the carrier lifetime (400 ns) in the untreated perovskite film. The carrier lifetime is closely related to the defects in the perovskite film. The existence of defects will accelerate the recombination of electron-hole pairs. The increase in the carrier lifetime indicates that some defects in the perovskite film have been passivated. Combining with the structure diagram of BTFIB, it can be found that there are lone pair electrons in the F atoms and O atoms in BTFIB, which can coordinate with the uncoordinated Pb atoms at the grain boundaries and surfaces of the perovskite film, thereby reducing the defect density of the perovskite film.

[0050] IV. The perovskite films prepared in Example 1 and Comparative Example 1 are used to prepare solar cells. The specific steps are as follows: Transfer the ITO glass substrate / 4PADCB / perovskite to a vacuum chamber, and use the method of thermal evaporation to sequentially deposit 20 nm of fullerene (C 60 ), 5 nm of bathocuproine (BCP), and 100 nm of Cu on the perovskite film, thus completing the preparation of the wide-bandgap perovskite solar cell (see Figure 2 ). Then, the current density-voltage characteristic curve and the decay diagram of the conversion efficiency with storage time of the battery are detected respectively. The results are shown in Figures 7-8 .

[0051] As Figure 7 can be seen, the photoelectric conversion efficiency of the untreated device in Comparative Example 1 is 20.6%. In Example 1, through BTFIB doping, both the open-circuit voltage and the fill factor of the device are greatly improved, and the device efficiency reaches 23.0%.

[0052] As Figure 8 can be seen, the perovskite solar cell treated with BTFIB in Example 1 shows better storage stability. After aging for nearly 1600 h, the device can still maintain more than 90% of the initial efficiency, while the untreated device in Comparative Example 1 drops below 90% of the initial efficiency after aging for 780 h.

[0053] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a wide bandgap perovskite film, characterized in that: The following steps are included in sequence: (1) Preparation of hole transport layer: coating a glass substrate with an ethanol solution of (4-(7H-dibenzo[c,g]carbazole-7-yl)butyl)phosphonic acid, followed by annealing to prepare a glass substrate / 4PADCB; (2) Preparation of perovskite light absorbing layer: A wide bandgap mixed perovskite precursor solution is coated on the glass substrate / 4PADCB prepared in step (1), and anti-solvent diethyl carbonate is added dropwise during the coating process, followed by annealing, and then coated with a 1,3-diaminopropane dihydroiodide post-treatment solution to obtain a wide bandgap perovskite film.

2. The method for preparing a wide bandgap perovskite film according to claim 1, characterized in that: In step (1), the glass substrate is pretreated before coating, and the pretreatment process includes the following steps: first rinsing with deionized water containing a detergent, then ultrasonically treating with deionized water and ethanol for 20-30 minutes each, then drying with nitrogen, and finally treating under ultraviolet and ozone conditions for 15-20 minutes.

3. The method for preparing a wide bandgap perovskite film according to claim 1, characterized in that: In step (1), the annealing temperature is 100-120°C and the annealing time is 10-15 minutes.

4. The method for preparing a wide bandgap perovskite film according to claim 1, characterized in that: In step (2), the wide bandgap mixed perovskite precursor solution is prepared by the following steps: in a nitrogen environment, adding FA weighed in molar ratio to 0.8 Cs 0.15 MA 0.05 PbI 2.4 Br 0.6 Pb(SCN)2 is added to perovskite, and then [bis(trifluoroacetyloxy)iodo]benzene is added to obtain a mixture, and the mixture is dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide, and stirred to obtain the product.

5. The method for preparing a wide bandgap perovskite film according to claim 1, characterized in that: In step (2), the annealing temperature is 60-100°C and the annealing time is 2-15 minutes.

6. The method for preparing a wide bandgap perovskite film according to claim 1, characterized in that: In step (2), the 1,3-diaminopropane dihydroiodide post-treatment solution is prepared by the following method: isopropanol and chlorobenzene are mixed to prepare a mixed solvent, the mixed solvent and 1,3-diaminopropane dihydroiodide are mixed at a liquid-to-solid ratio of 5 mL: 5-10 mg, and the mixture is stirred under a nitrogen environment for 4-8 hours to obtain the obtained solution.

7. A wide bandgap perovskite film obtained by the method for preparing a wide bandgap perovskite film according to any one of claims 1 to 6.

8. Use of the wide bandgap perovskite film according to claim 7 in the preparation of solar cells.

9. Use of the wide bandgap perovskite film according to claim 8 in preparing a solar cell, characterized in that: The preparation method of the solar cell comprises the following steps: placing a wide bandgap perovskite film in a vacuum, and then sequentially depositing 18-22nm fullerene, 4-7nm bathocuproin and 90-150nm metal copper to obtain the solar cell.

10. Use of the wide bandgap perovskite film according to claim 9 in preparing solar cells, characterized in that: The deposition method is thermal evaporation.

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