A perovskite solar cell for eliminating stress in perovskite thin films and its fabrication method

Abstract

This invention discloses a perovskite solar cell with stress-relieving properties and its fabrication method, belonging to the field of optoelectronic materials and devices. The invention involves spin-coating a hole transport layer onto a conductive glass substrate, preparing a SnO2 electron transport layer via chemical bath deposition, adding specific small ions to the perovskite film precursor solution, and then spin-coating the perovskite precursor solution. The perovskite layer is then obtained through spin-coating and annealing using an anti-solvent method. The hole transport layer is then spin-coated again, and a metal electrode is thermally deposited to obtain the perovskite solar cell. This method deposits a perovskite precursor solution containing small ions onto a conductive substrate with a pre-deposited hole transport layer, producing a perovskite film with significant stress-relieving properties. The film surface is smooth and dense with a low defect state density. The fabricated perovskite solar cell exhibits excellent photoelectric conversion efficiency, as well as excellent long-term stability and resistance to environmental corrosion.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic materials and devices technology, and specifically relates to a perovskite solar cell that eliminates stress in a perovskite thin film by adding small ions and its preparation method. Background Technology

[0002] With societal progress and development, energy crises and environmental problems are becoming increasingly severe, making the development of efficient, clean, and renewable energy sources a crucial global research topic. Solar energy, due to its clean and sustainable characteristics, is considered one of the best alternatives to traditional fossil fuels. Perovskite solar cells, as a next-generation photovoltaic technology, have received widespread attention and research in recent years due to their high photoelectric conversion efficiency, low cost, and simple fabrication capabilities. Since their initial report in 2009, the photoelectric conversion efficiency of perovskite solar cells has rapidly increased from 3.8% to over 25%. However, the practical application and commercialization of perovskite solar cells still face many challenges, among which the stress problem in perovskite thin films is one of the key factors affecting their stability and performance.

[0003] Stress in perovskite thin films primarily originates from differences in the coefficients of thermal expansion of the materials or inhomogeneities during crystal growth during deposition and annealing. The presence of stress can lead to film cracking and increased grain boundary defects, thereby affecting the stability of the perovskite crystal, reducing the photoelectric conversion efficiency of the device, and shortening its lifespan. Therefore, effectively eliminating stress in perovskite thin films has become an important research direction for improving the performance and stability of perovskite solar cells. Summary of the Invention

[0004] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide a method for eliminating stress in perovskite thin films by introducing small ions. By introducing small ions during the perovskite thin film preparation process, the stress distribution in the film is effectively controlled, resulting in a smooth and dense film surface with a low defect state density. This improves the film's crystallinity, reduces the defect state density, and enhances photoelectric conversion efficiency and long-term device stability. The prepared perovskite solar cell exhibits excellent photoelectric conversion efficiency, along with superior long-term stability and resistance to environmental corrosion.

[0005] The present invention is achieved through the following technical solution.

[0006] One aspect of the present invention provides a method for fabricating a perovskite solar cell that eliminates stress in a perovskite thin film, comprising the following steps:

[0007] (1) Clean the FTO glass substrate, dry it, and then treat it with ultraviolet ozone.

[0008] (2) Lead iodide, formamidinium hydroiodate, methylamine hydrochloride and methylamine lead tribromide single crystal were dissolved in a mixed solvent in a molar ratio of (1.5-1.6):(1.2-1.4):(0.3-0.5):(0.01-0.2) to obtain a perovskite precursor solution;

[0009] (3) Tert-butylpyridine, tert-butylpyridine-sulfonylimide solution, lithium bis(trifluoromethanesulfonylimide) solution and 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene were dissolved in an organic solvent at a mass ratio of (10-30):(1-10):(5-20):(10-100) to obtain a hole transport layer precursor solution;

[0010] (4) A SnO2 electron transport layer was prepared on the cleaned FTO glass substrate by chemical bath deposition.

[0011] (5) On FTO transparent conductive glass with electron transport material deposited, germanium iodide is added to the perovskite precursor solution, and the perovskite precursor solution is spin-coated by spin coating; then spin-coated by anti-solvent method, and annealed to obtain the perovskite layer.

[0012] (6) A hole transport layer precursor solution is spin-coated onto an FTO transparent conductive glass with a perovskite layer deposited on it to obtain a hole transport layer coated on the perovskite layer.

[0013] (7) A metal electrode is thermally deposited on an FTO transparent conductive glass with a hole transport layer to obtain a perovskite solar cell.

[0014] Preferably, the mixed solvent is prepared by mixing N,N-dimethylformamide / dimethyl sulfoxide in a mass ratio of (5-10):(1-10).

[0015] Preferably, the tert-butylpyridine-sulfonylimide solution is prepared by dissolving 50-100 mg of tris(2-(1H-pyrazole-1-yl)-4-tert-butylpyridine)cobalt(III)tris[bis(trifluoromethane)sulfonylimide] in 100-1000 μL of acetonitrile.

[0016] Preferably, the organic solvent is one or more of chlorobenzene, anisole, or ethyl acetate.

[0017] Preferably, in step (5), the perovskite precursor solution is spin-coated, which includes: treating FTO transparent conductive glass with electron transport material deposited on it with ultraviolet ozone, and then spin-coating the perovskite precursor solution in a nitrogen atmosphere at a low speed of 1000-2000 rpm for 10-20 seconds, followed by a high speed of 5000-7000 rpm for 20-40 seconds.

[0018] Preferably, in step (5), the anti-solvent spin coating and annealing are performed, including:

[0019] Anhydrous ether was added dropwise in the last 15 seconds as an antisolvent. After aging the perovskite film, it was annealed at 100–150°C for 0.5–3 hours. After cooling to room temperature, an iodate solution was spin-coated at 3000–5000 rpm for 30–60 seconds, and then immediately annealed at 100–150°C for 5–8 minutes.

[0020] Preferably, the iodate solution is n-octylamine hydroiodate or 4-methoxyphenylethyl ammonium iodide dissolved in isopropanol, with a concentration of 3.5-4 mg / mL.

[0021] Preferably, in step (6), the hole transport layer precursor solution is spin-coated onto the FTO transparent conductive glass with the perovskite layer deposited at 4000-6000 rpm for 20-60 seconds.

[0022] In step (7), a gold electrode is thermally deposited on the FTO transparent conductive glass with a hole transport layer, with a thickness of 100-200 nm.

[0023] In another aspect, the present invention provides a perovskite solar cell with stress-relieved perovskite thin film prepared by the method described above.

[0024] The present invention, by adopting the above technical solution, has the following beneficial effects:

[0025] 1. Effectively Eliminating Stress in Thin Films: By introducing appropriate amounts of small ions (such as lithium ions and potassium ions) into the perovskite precursor solution, these ions can enter the crystal lattice or reside at grain boundaries during perovskite film formation, significantly regulating the stress distribution within the film. This effectively reduces stress concentration, preventing film cracking and grain boundary defects, thereby improving the crystallinity of the perovskite film. By reducing stress-induced crystal defects, the film surface becomes smoother and denser, significantly enhancing film stability.

[0026] 2. Improved Photovoltaic Conversion Efficiency and Device Stability: This invention, by introducing small ions, not only improves the crystal structure of the perovskite thin film and reduces the defect state density, but also enhances the interfacial contact performance between the thin film and the electron transport layer. These improvements significantly increase the photovoltaic conversion efficiency of perovskite solar cells. Furthermore, the long-term stability of the device is also significantly improved, maintaining excellent performance under extreme environments such as light, heat, and humidity, making it suitable for long-term use.

[0027] 3. Simple and easy-to-implement process, suitable for large-scale production: The method of adding small ions proposed in this invention is simple, easy to operate, and suitable for large-scale preparation. Compared with other complex stress control methods, the method of using small ions to regulate stress is lower in cost and has strong applicability. This method is not only applicable to perovskite solar cells, but can also be used to prepare other types of perovskite optoelectronic devices, and has broad application prospects.

[0028] 4. Excellent Device Performance and Commercial Potential: Perovskite solar cells fabricated using this method exhibit a denser thin-film structure and superior photoelectric performance, demonstrating excellent photoelectric conversion efficiency and long-term stability. This method not only improves device performance in laboratory environments but also provides a reliable technological foundation for the commercial application of perovskite solar cells, demonstrating significant market potential. Attached Figure Description

[0029] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, do not constitute an undue limitation of the invention. In the drawings:

[0030] Figure 1 This is a structural diagram of the perovskite solar cell device prepared in a nitrogen atmosphere according to the present invention;

[0031] Figure 2(a) and (b) are SEM images of the perovskite thin film with low defect state density and smooth and dense surface prepared in a nitrogen atmosphere according to the present invention and the perovskite thin film prepared without the addition of small ion radius materials.

[0032] Figures 3(a) and (b) are grazing incidence wide-angle X-ray scattering diagrams of the perovskite film prepared in a nitrogen atmosphere and the perovskite film prepared without the addition of small ion radius materials according to the present invention.

[0033] Figures 4(a) and (b) are grazing incidence X-ray diffraction patterns of the perovskite film prepared in a nitrogen atmosphere and the perovskite film prepared without the addition of small ion radius materials according to the present invention.

[0034] Figure 5 The JV curves are shown for the perovskite solar cells prepared in a nitrogen atmosphere and the perovskite solar cells prepared without the addition of small ion radius materials according to the present invention.

[0035] Figure 6 The graphs show the changes in photoelectric conversion efficiency over time of perovskite solar cells prepared in a nitrogen atmosphere and perovskite solar cells prepared without the addition of small ion radius materials under illumination in a nitrogen atmosphere. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0037] The method for eliminating internal stress in perovskite thin films and the method for perovskite solar cells provided in this invention include the following steps:

[0038] Step 1: Clean the FTO glass substrate sequentially with detergent, deionized water, acetone, and anhydrous ethanol, with each cleaning step lasting 20 minutes. Then, after the FTO glass is dried, treat it with ultraviolet ozone (UV-Ozone) for 20 minutes.

[0039] Step 2: Dissolve lead iodide, formamidinium hydroiodate, methylamine hydrochloride, and methylamine lead tribromide single crystals in a mixed solvent of N,N-dimethylformamide / dimethyl sulfoxide (volume ratio of (5-10):(1-10)) at a molar ratio of (1.5-1.6):(1.2-1.4):(0.3-0.5):(0.01-0.2), and stir for more than 3-6 hours to obtain a perovskite precursor solution.

[0040] Step 3: Dissolve tert-butylpyridine, tris(2-(1H-pyrazole-1-yl)-4-tert-butylpyridine)cobalt(III)tris[bis(trifluoromethane)sulfonylimide] solution (50-100 mg of tris(2-(1H-pyrazole-1-yl)-4-tert-butylpyridine)cobalt(III)tris[bis(trifluoromethane)sulfonylimide] in 100-1000 μL of acetonitrile), lithium bis(trifluoromethane)sulfonylimide solution, and 2,2',7,7'-tetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene in organic solvents such as chlorobenzene, anisole, or ethyl acetate according to a mass ratio of (10-30):(1-10):(5-20):(10-100) to obtain a hole transport layer precursor solution.

[0041] Step 4: Prepare a SnO2 electron transport layer on the cleaned FTO glass substrate by chemical bath deposition (CBD).

[0042] Step 5: Treat the FTO transparent conductive glass with deposited electron transport material using ultraviolet ozone for 10 minutes. Then, add germanium iodide to the perovskite precursor solution. Inject the perovskite precursor solution into a nitrogen glove box and spin-coat at 1000–2000 rpm for 10–20 seconds, followed by 5000–7000 rpm for 20–40 seconds. Add 500 μL of anhydrous ether as an anti-solvent in the last 15 seconds. After deposition, age the perovskite film briefly in the glove box, then anneal at 100–150°C for 0.5–3 hours.

[0043] After cooling to room temperature, spin coat the mixture with n-octyl hydroiodide or 4-methoxyphenylethyl ammonium iodide solution (dissolved in isopropanol, concentration 3.5-4 mg / mL) at 3000-5000 rpm for 30-60 seconds, and immediately anneal at 100-150°C for 5-8 minutes.

[0044] Figure 1 Figure 2(a) and (b) are SEM images of the perovskite solar cell device prepared in a nitrogen atmosphere according to the present invention and the perovskite film prepared without the addition of small ion radius materials. Figure 3(a) and (b) are grazing incidence wide-angle X-ray scattering images of the perovskite film prepared in a nitrogen atmosphere and the perovskite film prepared without the addition of small ion radius materials according to the present invention.

[0045] Step 6: Apply the hole transport layer to the top of the perovskite layer by spin coating FTO transparent conductive glass with the perovskite layer at 4000-6000 rpm for 20-60 seconds.

[0046] Step 7: A 100-200 nm thick gold electrode is thermally deposited on the FTO transparent conductive glass with a hole transport layer by thermal evaporation. The prepared device is then subjected to oxidation treatment for more than 24 hours. The thorough oxidation process helps to improve the device performance and obtain a perovskite solar cell.

[0047] Figures 4(a) and (b) are grazing incidence X-ray diffraction patterns of the perovskite film prepared in a nitrogen atmosphere and the perovskite film prepared without the addition of small ion radius materials according to the present invention. As can be seen from the figures, the addition of small ion radius materials can significantly improve the quality and performance of the perovskite film. Figure 5 The JV curves are shown for the perovskite solar cells prepared in a nitrogen atmosphere and the perovskite solar cells prepared without the addition of small ion radius materials according to the present invention. Figure 6 This figure shows the photoelectric conversion efficiency (PCE) over time of perovskite solar cells prepared in a nitrogen atmosphere and perovskite solar cells prepared without the addition of small ionic radius materials, under illumination in a nitrogen atmosphere. As can be seen from the figure, the addition of small ionic radius materials can significantly improve the quality and performance of the perovskite thin film.

[0048] The present invention will be further illustrated below through different embodiments.

[0049] Example 1

[0050] This embodiment describes an inverted planar heterojunction solar cell prepared using a method for eliminating internal stress in perovskite thin films and a method for preparing perovskite solar cells, in order to fully understand the present invention. The main steps include:

[0051] Step 1) Clean the FTO glass substrate sequentially with detergent, deionized water, acetone, and anhydrous ethanol, with each cleaning step lasting 20 minutes. Then, after the FTO glass is dried, treat it with ultraviolet ozone (UV-Ozone) for 20 minutes.

[0052] Step 2) Dissolve lead iodide, formamidinium hydroiodate, methylamine hydrochloride, and methylamine lead tribromide single crystals in a mixed solvent of N,N-dimethylformamide / dimethyl sulfoxide (volume ratio 8:1) at a molar ratio of 1.5:1.3:0.4:0.1, and stir for more than 3 hours. Then, 8 minutes before spin coating, add germanium iodide to the perovskite precursor solution and mix thoroughly to prepare the perovskite precursor solution for later use.

[0053] Step 3) Dissolve 4-tert-butylpyridine, tris(2-(1H-pyrazole-1-yl)-4-tert-butylpyridine)cobalt(III)tris[bis(trifluoromethane)sulfonylimide] solution (75 mg tris(2-(1H-pyrazole-1-yl)-4-tert-butylpyridine)cobalt(III)tris[bis(trifluoromethane)sulfonylimide] dissolved in 200 μL acetonitrile), lithium bis(trifluoromethane)sulfonylimide solution (260 mg lithium bis(trifluoromethane)sulfonylimide dissolved in 500 μL acetonitrile), and 2,2',7,7'-tetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene in chlorobenzene according to a mass ratio of 20:5:20:10, and stir well to prepare the hole transport layer precursor solution for later use.

[0054] Step 4) Prepare a SnO2 electron transport layer on the cleaned FTO glass substrate by chemical bath deposition (CBD).

[0055] Step 5) Treat the FTO transparent conductive glass with deposited electron transport material with ultraviolet ozone for 10 minutes. Then, add germanium iodide to the perovskite precursor solution. Spin-coat the perovskite precursor solution in a nitrogen glove box at 1500 rpm for 15 seconds, then at 6000 rpm for 30 seconds, adding 500 μL of anhydrous ether as an antisolvent in the last 15 seconds. After deposition, age the perovskite film briefly in a glove box, then anneal at 100°C for 3 hours.

[0056] After cooling to room temperature, spin coat at 4000 rpm for 50 seconds using n-octyl hydroiodate or 4-methoxyphenylethyl ammonium iodide solution (dissolved in isopropanol, concentration 3.5-4 mg / mL), and immediately anneal at 100°C for 8 minutes.

[0057] Step 6) Apply the hole transport layer to the top of the perovskite layer using an FTO transparent conductive glass with a deposited perovskite layer by spin coating at 4000 rpm for 30 seconds.

[0058] Step 7) A 100 nm thick gold electrode is thermally deposited on the FTO transparent conductive glass with a hole transport layer by thermal evaporation. The prepared device is then subjected to oxidation treatment for more than 24 hours. The thorough oxidation process helps to improve the device performance.

[0059] Under standard test conditions (AM1.5G illumination), the solar cell device fabricated in this example exhibits a photoelectric conversion efficiency of 25.35%, an open-circuit voltage of 1.182V, and a short-circuit current of 25.23mA / cm². 2 The fill factor is 84.67%.

[0060] Example 2

[0061] Step 1) Clean the FTO glass substrate sequentially with detergent, deionized water, acetone, and anhydrous ethanol, with each cleaning step lasting 20 minutes. Then, after the FTO glass is dried, treat it with ultraviolet ozone (UV-Ozone) for 20 minutes.

[0062] Step 2) Dissolve lead iodide, formamidinium hydroiodate, methylamine hydrochloride, and methylamine lead tribromide single crystals in a mixed solvent of N,N-dimethylformamide / dimethyl sulfoxide (volume ratio 8:1) at a molar ratio of 1.6:1.2:0.3:0.2, and stir for more than 3 hours. Then, 10 minutes before spin coating, add germanium iodide to the perovskite precursor solution and mix thoroughly to prepare the perovskite precursor solution for later use.

[0063] Step 3) Dissolve 4-tert-butylpyridine, tris(2-(1H-pyrazole-1-yl)-4-tert-butylpyridine)cobalt(III)tris[bis(trifluoromethane)sulfonylimide] solution (75 mg tris(2-(1H-pyrazole-1-yl)-4-tert-butylpyridine)cobalt(III)tris[bis(trifluoromethane)sulfonylimide] dissolved in 200 μL acetonitrile), lithium bis(trifluoromethane)sulfonylimide solution (260 mg lithium bis(trifluoromethane)sulfonylimide dissolved in 500 μL acetonitrile), and 2,2',7,7'-tetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene in chlorobenzene at a mass ratio of 30:1:5:100, and stir well to prepare the hole transport layer precursor solution for later use.

[0064] Step 4) Prepare a SnO2 electron transport layer on the cleaned FTO glass substrate by chemical bath deposition (CBD).

[0065] Step 5) Treat the FTO transparent conductive glass with deposited electron transport material with ultraviolet ozone for 10 minutes. Then, add germanium iodide to the perovskite precursor solution. Spin-coat the perovskite precursor solution in a nitrogen glove box at 1000 rpm for 20 seconds, then at 5000 rpm for 40 seconds, and add 500 μL of anhydrous ether as an antisolvent in the last 15 seconds. After deposition, age the perovskite film briefly in a glove box, then anneal at 150°C for 0.5 hours.

[0066] After cooling to room temperature, spin-coat the solution at 3000 rpm for 60 seconds using n-octyl hydroiodate or 4-methoxyphenylethyl ammonium iodide solution (dissolved in isopropanol, concentration 3.5-4 mg / mL), and immediately anneal at 120°C for 6 minutes.

[0067] Step 6) Apply the hole transport layer to the top of the perovskite layer using an FTO transparent conductive glass with a deposited perovskite layer by spin coating at 6000 rpm for 20 seconds.

[0068] Step 7) A 150 nm thick gold electrode is thermally deposited on the FTO transparent conductive glass with a hole transport layer by thermal evaporation. The prepared device is then subjected to oxidation treatment for more than 24 hours. The thorough oxidation process helps to improve the device performance.

[0069] Under standard test conditions (AM1.5G illumination), the solar cell device fabricated in this example exhibits a photoelectric conversion efficiency of 24.56%, an open-circuit voltage of 1.166V, and a short-circuit current of 25.12mA / cm². 2 The fill factor is 82.65%.

[0070] Example 3

[0071] Step 1) Clean the FTO glass substrate sequentially with detergent, deionized water, acetone, and anhydrous ethanol, with each cleaning step lasting 20 minutes. Then, after the FTO glass is dried, treat it with ultraviolet ozone (UV-Ozone) for 20 minutes.

[0072] Step 2) Dissolve lead iodide, formamidinium hydroiodate, methylamine hydrochloride, and methylamine lead tribromide single crystals in a mixed solvent of N,N-dimethylformamide / dimethyl sulfoxide (volume ratio 8:1) at a molar ratio of 1.55:1.4:0.5:0.01, and stir for more than 3 hours. Then, 5 minutes before spin coating, add germanium iodide to the perovskite precursor solution and mix thoroughly to prepare the perovskite precursor solution for later use.

[0073] Step 3) Dissolve 4-tert-butylpyridine, tris(2-(1H-pyrazole-1-yl)-4-tert-butylpyridine)cobalt(III)tris[bis(trifluoromethane)sulfonylimide] solution (75 mg tris(2-(1H-pyrazole-1-yl)-4-tert-butylpyridine)cobalt(III)tris[bis(trifluoromethane)sulfonylimide] dissolved in 200 μL acetonitrile), lithium bis(trifluoromethane)sulfonylimide solution (260 mg lithium bis(trifluoromethane)sulfonylimide dissolved in 500 μL acetonitrile), and 2,2',7,7'-tetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene in chlorobenzene according to a mass ratio of 10:10:12:50, and stir well to prepare the hole transport layer precursor solution for later use.

[0074] Step 4) Prepare a SnO2 electron transport layer on the cleaned FTO glass substrate by chemical bath deposition (CBD).

[0075] Step 5) Treat the FTO transparent conductive glass with deposited electron transport material with ultraviolet ozone for 10 minutes. Then, add germanium iodide to the perovskite precursor solution. Spin-coat the perovskite precursor solution in a nitrogen glove box at 2000 rpm for 10 seconds, then at 7000 rpm for 20 seconds, and add 500 μL of anhydrous ether as an antisolvent in the last 15 seconds. After deposition, age the perovskite film briefly in a glove box, then anneal at 120°C for 2 hours.

[0076] After cooling to room temperature, spin coat at 5000 rpm for 30 seconds using n-octyl hydroiodate or 4-methoxyphenylethyl ammonium iodide solution (dissolved in isopropanol, concentration 3.5-4 mg / mL), and immediately anneal at 150°C for 5 minutes.

[0077] Step 6) Apply the hole transport layer to the top of the perovskite layer using an FTO transparent conductive glass with a perovskite layer deposited on it by spin coating at 5000 rpm for 60 seconds.

[0078] Step 7) A 200 nm thick gold electrode is thermally deposited on the FTO transparent conductive glass with a hole transport layer by thermal evaporation. The prepared device is then subjected to oxidation treatment for more than 24 hours. The thorough oxidation process helps to improve the device performance.

[0079] Under standard test conditions (AM1.5G illumination), the solar cell device fabricated in this example exhibits a photoelectric conversion efficiency of 23.88%, an open-circuit voltage of 1.180V, and a short-circuit current of 25.09mA / cm². 2 The fill factor is 81.17%.

[0080] As can be seen from the above embodiments, the perovskite solar cell prepared by the present invention has a photoelectric conversion efficiency of not less than 23.88%, an open-circuit voltage of 1.182V, and a short-circuit current of not more than 25.23mA / cm². 2 The fill factor is not less than 81.17%. It has excellent electron extraction and transport capabilities, and its smooth and dense surface has good water and oxygen barrier capabilities, which greatly improves the photoelectric conversion efficiency and device stability of perovskite solar cells.

[0081] This invention addresses the common problem that stress concentration during the deposition and annealing of traditional perovskite thin films often leads to cracking, increased grain boundary defects, and decreased film quality, ultimately affecting the performance and stability of perovskite solar cells. This invention introduces specific small ions into the perovskite precursor solution. These ions can effectively bind to the perovskite lattice or distribute at grain boundaries, regulating the stress distribution of the film and reducing stress concentration. This alleviates stress in the film, controls the crystal growth process, improves the crystal quality of the film, and significantly reduces the defect state density, thereby enhancing the photoelectric conversion efficiency and long-term stability of the device, ultimately leading to the fabrication of highly efficient and stable perovskite solar cells.

[0082] The perovskite solar cells prepared by this method exhibit superior photoelectric conversion efficiency and long-term stability due to the effective release of thin film stress, resulting in a denser and smoother thin film surface and excellent interfacial contact performance. This makes them highly promising for commercial applications.

[0083] This invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and modifications to some of the technical features without creative effort, and all such substitutions and modifications are within the protection scope of this invention.

Claims

1. A method for fabricating a perovskite solar cell with stress-relieved perovskite thin film, characterized in that, Includes the following steps: (1) Clean the FTO glass substrate, dry it, and then treat it with ultraviolet ozone. (2) Lead iodide, formamidinium hydroiodate, methylamine hydrochloride and methylamine lead tribromide single crystal were dissolved in a mixed solvent in a molar ratio of (1.5-1.6):(1.2-1.4):(0.3-0.5):(0.01-0.2) to obtain a perovskite precursor solution; The mixed solvent is prepared by mixing N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of (5-10):(1-10); (3) Dissolve tert-butylpyridine, tert-butylpyridine-sulfonylimide solution, lithium bis(trifluoromethanesulfonylimide) solution and 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene in an organic solvent according to a mass ratio of (10-30):(1-10):(5-20):(10-100) to obtain a hole transport layer precursor solution; The tert-butylpyridine-sulfonylimide solution was prepared by dissolving 50-100 mg of tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III)tris[bis(trifluoromethane)sulfonylimide] in 100-1000 μL of acetonitrile. The organic solvent is one or more of chlorobenzene, anisole, or ethyl acetate; (4) A SnO2 electron transport layer was prepared on the cleaned FTO glass substrate by chemical bath deposition. (5) Add germanium iodide to the perovskite precursor solution on the FTO transparent conductive glass on which electron transport material is deposited, and spin-coat the perovskite precursor solution by spin coating. Then, the perovskite layer is obtained by spin coating using an anti-solvent method and followed by annealing. (6) Spin-coat the hole transport layer precursor solution onto the FTO transparent conductive glass with the perovskite layer deposited, to obtain the hole transport layer coated on the perovskite layer. (7) A metal electrode is thermally deposited on an FTO transparent conductive glass with a hole transport layer to obtain a perovskite solar cell.

2. The method for fabricating a perovskite solar cell with stress-relieved perovskite thin film according to claim 1, characterized in that, In step (5), the perovskite precursor solution is spin-coated, which includes: treating FTO transparent conductive glass with electron transport material deposited on it with ultraviolet ozone, and then spin-coating the perovskite precursor solution in a nitrogen atmosphere at a low speed of 1000~2000 rpm for 10~20 seconds, and then at a high speed of 5000~7000 rpm for 20~40 seconds.

3. The method for fabricating a perovskite solar cell with stress-relieved perovskite thin film according to claim 2, characterized in that, In step (5), the anti-solvent spin coating and annealing are performed, including: Anhydrous ether, the antisolvent, is added dropwise during the last 15 seconds of high-speed rotation to deposit the perovskite film. After aging, the film is annealed at 100-150°C for 0.5-3 hours. After cooling to room temperature, an iodate solution is spin-coated at 3000-5000 rpm for 30-60 seconds, and then immediately annealed at 100-150°C for 5-8 minutes.

4. The method for preparing a perovskite solar cell with stress-relieved perovskite thin film according to claim 3, characterized in that, The iodate solution is n-octylamine hydroiodate or 4-methoxyphenylethyl ammonium iodide dissolved in isopropanol, with a concentration of 3.5-4 mg / mL.

5. The method for fabricating a perovskite solar cell with stress-relieved perovskite thin film according to claim 1, characterized in that, In step (6), the hole transport layer precursor solution is spin-coated onto the FTO transparent conductive glass with the perovskite layer deposited at 4000-6000 rpm for 20-60 seconds. In step (7), a gold electrode is thermally deposited on the FTO transparent conductive glass with a hole transport layer, with a thickness of 100~200 nm.

6. A perovskite solar cell with stress-relieved perovskite thin film prepared by the method according to any one of claims 1-5.

7. The perovskite solar cell with stress-relieved perovskite thin film as described in claim 6 is applied in the field of optoelectronics.

Images