A method for preparing a high-efficiency stable perovskite solar cell by a low-temperature process
By preparing FAPbI3 perovskite thin films using a low-temperature process and an anti-solvent method, the problems of poor operability of mesophase formation and small crystal size were solved, realizing a highly efficient and stable perovskite solar cell with excellent energy conversion efficiency and industrialization potential.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-03-25
- Publication Date
- 2026-04-07
AI Technical Summary
When FAPbI3 perovskite is prepared using the traditional anti-solvent method, it suffers from poor operability of mesophase formation and small crystal size, resulting in low photovoltaic device performance and poor repeatability.
A low-temperature process was adopted, in which the FAPbI3 perovskite precursor solution was dissolved by stirring at -10℃ to -20℃, and then spin-coated and annealed in an anhydrous and oxygen-free glove box using an anti-solvent method to prepare a dense and smooth perovskite film. Subsequently, a hole transport layer and an interface modification layer were spin-coated, and finally a metal electrode was vacuum-deposited.
FAPbI3 perovskite thin films with micron-sized and dense, smooth morphology were fabricated, enabling highly efficient and stable perovskite solar cells with an energy conversion efficiency of over 23.62%, thus improving the stability and performance of the devices.
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Figure CN116867334B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing FAPbI3 perovskite thin films and high-efficiency perovskite solar cells by adjusting the temperature during the formation of the perovskite precursor solution and the mesophase using a low-temperature process and an anti-solvent method. In particular, it relates to a method for stably preparing high-efficiency formamidinium-based perovskite thin films using a low-temperature process, belonging to the field of optoelectronic materials and technology. Background Technology
[0002] Energy is one of the major problems facing the world today. Traditional fossil fuels such as oil and coal, due to their non-renewable nature, are gradually failing to meet the ever-increasing energy demands of humanity. Therefore, people are seeking alternatives, which are collectively referred to as new energy sources, including wind power, hydropower, and solar energy. Among these, solar energy has received widespread attention due to its massive energy output, wide coverage area, and relatively low construction requirements. Solar cell development has gone through three generations: the first generation of traditional silicon solar cells, the second generation of thin-film solar cells, and the third generation of novel solar cells. Perovskite materials, with their strong light absorption, high carrier mobility, low exciton binding energy, and long charge diffusion distance, are a typical representative of the third generation of novel solar cells.
[0003] Novel solar cells, including perovskite solar cells, dye-sensitized solar cells, organic solar cells, and quantum dot solar cells, have emerged. Among them, perovskite solar cells have attracted much attention internationally due to their low cost, simple fabrication, and excellent photoelectric conversion performance. Therefore, they have significant advantages over existing mature crystalline silicon solar cell technology, bringing optimistic prospects for the commercial application of perovskite solar cells. Among perovskite materials, FAPbI3 perovskite (where FA is formamidinium) has been proven to be an ideal candidate for preparing high-efficiency and stable perovskite solar cells. However, FAPbI3 undergoes a phase transition from the optically active α phase to the optically inactive δ phase below 150℃. Therefore, obtaining highly crystalline, stable, and pure α-phase FAPbI3 perovskite thin films is crucial for the practical and widespread application of perovskite solar cells. Previous research mainly focused on doping with MA... + (methylamine), Cs + Or Br - Plasma is used to obtain pure α-phase FAPbI3 perovskite, but doping with these ions causes a blue shift in the UV-Vis absorption peak of the perovskite material, resulting in a widening of the band gap. Although this increases the open-circuit voltage (V) of the device... OC However, it will reduce the short-circuit current density (J). SCFAPbI3 has a band gap (~1.48V) that is closest to the ideal band gap (1.3V-1.4V) among known perovskite materials. More importantly, these doping strategies can affect the stability of the device to some extent. Therefore, it is particularly important to use a reagent or method that can obtain pure α-phase FAPbI3 without changing its band gap. Summary of the Invention
[0004] The technical problem solved by this invention is the poor operability of mesophase formation and small crystal size in the preparation of FAPbI3 perovskite by the traditional antisolvent method, which leads to low performance and poor repeatability of photovoltaic devices. The optimal battery device prepared by this invention has an energy conversion efficiency of more than 23.62%, and the perovskite thin film prepared by it has a micron-level size and a dense and smooth morphology.
[0005] To address the above problems, the technical solution proposed in this invention is: a method for preparing high-efficiency and stable formamidinium-based perovskite solar cells using a low-temperature process, comprising the following steps:
[0006] (1) Dissolve lead iodide, formamidine iodide, and additive methylamine chloride in a molar ratio of 1.1:1:0.3 in a mixed solution of N,N-dimethylformamide solvent and dimethyl sulfoxide in a volume ratio of 8:1 to prepare a new FAPbI3 perovskite precursor solution. Stir and dissolve the solution in an environment of -10°C to -20°C for 1 to 3 hours.
[0007] (1) Electron transport material is spin-coated onto a cleaned and treated FTO transparent conductive glass sheet;
[0008] (2) In an anhydrous and oxygen-free glove box, the prepared low-temperature perovskite precursor solution was spin-coated onto an FTO conductive substrate with an electron transport layer cooled to -10°C to -20°C, and diethyl ether, an antisolvent cooled to -10°C to -20°C, was added dropwise to obtain an intermediate phase film.
[0009] (3) The mesophase film was annealed at 155°C for 10 minutes to obtain a smooth and dense perovskite film.
[0010] (4) A solution of butylamine hydroiodide was spin-coated onto the perovskite layer for post-treatment;
[0011] (5) Spin-coating a hole transport layer onto the perovskite layer;
[0012] (6) Vacuum evaporation of an interface modification layer and a metal electrode on the hole transport layer.
[0013] Preferably, the concentration of the FAPbI3 perovskite precursor solution in step (1) is 900-1300 mg / mL.
[0014] Preferably, in step (1), the precursor solution is dissolved by stirring at low temperature. The specific steps are as follows:
[0015] (1) Lead iodide, formamidine iodide, and methylamine chloride (an additive) are added to a solution of N,N-dimethylformamide solvent and dimethyl sulfoxide in a volume ratio of 8:1.
[0016] (2) Stir until dissolved in an environment with a temperature of -10℃ to -20℃.
[0017] Preferably, the electron transport layer on the transparent conductive FTO glass in step (2) is SnO2, and the specific steps are as follows:
[0018] (1) Spin coating conditions: 4000 rpm for 30 seconds.
[0019] (2) After spin coating, anneal at 150℃ for 30 minutes.
[0020] Preferably, the thin film preparation in step (3) is carried out by spin coating and annealing in an anhydrous and oxygen-free glove box. The specific steps are as follows:
[0021] (1) The spin coating conditions are: spin coating at 1000 rpm for 10 seconds, then spin coating at 5000 rpm for 30 seconds.
[0022] (2) Before spin coating, the FTO glass coated with SnO2 electron transport layer is cooled to -10℃ to -20℃.
[0023] (3) After spin coating at 5000 rpm for 10 s, add 400 μL of diethyl ether at -10℃ to -20℃ as an anti-solvent.
[0024] (4) After spin coating, annealing is performed on a hot plate at 155°C for 10 minutes. Preferably, the hole transport layer deposited by spin coating in step (6) is Spiro-OMeTAD; the specific steps are as follows:
[0025] (1) Dissolve 73.2 mg of Spiro-OMeTAD in 1 mL of chlorobenzene;
[0026] (2) Dissolve 520 mg of lithium bis(trifluoromethanesulfonate) in 1 mL of acetonitrile solution.
[0027] (3) Add 28.8 μL of TBP solution to Spiro-OMeTAD solution;
[0028] (4) Add 17.6 μL of lithium salt solution to Spiro-OMeTAD solution;
[0029] (5) Stir the mixed solution at room temperature for 2 hours;
[0030] (6) Spin coating conditions are 2500 rpm for 30 seconds.
[0031] Preferably, in step (7), the interface modification layer is MoO3, and the metal electrode is Ag. The specific steps are as follows:
[0032] (1) MoO3 was vapor-deposited on the hole transport layer with a thickness of 5 nm;
[0033] (2) The thickness of the metal Ag electrode is 100 nm.
[0034] To solve the technical problem of the present invention, the technical solution proposed by the present invention is: the FAPbI3 perovskite thin film prepared by the method and its perovskite solar cell.
[0035] To solve the technical problem of this invention, the technical solution proposed by this invention is: the preparation of FAPbI3 perovskite thin film and its application in the field of optoelectronics.
[0036] The beneficial effects of this invention are:
[0037] (1) Previous studies mainly focused on doping Cs + Or Br - Plasma is used to obtain high-performance FAPbI3 perovskites, but doping with these ions causes a blue shift in the UV-Vis absorption peak of the perovskite material, resulting in a widening of the band gap. Although this increases the open-circuit voltage (V) of the device... OC However, it will reduce the short-circuit current density (J). SC The band gap of FAPbI3 (~1.48V) is the closest to the ideal band gap (1.3V-1.4V) among known perovskite materials. However, the formamidinium-based perovskite solar cell prepared in this invention obtains a uniform and dense perovskite film using a low-temperature process without affecting the band gap, thereby enabling the preparation of FAPbI3 perovskite solar cells with excellent power conversion efficiency.
[0038] (2) Currently, the main methods for preparing formamidine-based perovskite solar cells are one-step and two-step methods. The performance of perovskite devices prepared by the one-step method is relatively low, while the two-step method is more complicated. However, this invention uses a low-temperature anti-solvent method at -10℃ to -20℃ to prepare FAPbI3 perovskite solar cells, which can stably produce high-performance FAPbI3 perovskite solar cells. The optimal energy conversion efficiency of the prepared cell device is above 23.62%. The perovskite thin film prepared has a micron-level size and a dense and smooth morphology, which is conducive to its industrialization.
[0039] (3) By adjusting the temperature of the precursor and the mesophase from -10℃ to -20℃, a uniform and dense FAPbI3 perovskite film can be prepared. Attached Figure Description
[0040] The invention will now be further described with reference to the accompanying drawings.
[0041] Figure 1 This is the XRD pattern of the FAPbI3 thin film prepared with precursor solutions at 60℃ and -15℃ in this invention;
[0042] Figure 2 These are SEM images of FAPbI3 films prepared with precursor solutions at 60°C, 0°C, and -15°C in this invention.
[0043] Figure 3 This is a device structure diagram of the FAPbI3 perovskite solar cell prepared in this invention;
[0044] Figure 4 This is a JV curve diagram of perovskite solar cells when the perovskite precursor solution is at 60℃, room temperature (20℃), 0℃, -15℃, and -20℃. Detailed Implementation
[0045] Example 1
[0046] This embodiment describes the process of controlling the phase formation temperature between the perovskite precursor solution and the mesophase to obtain large-grain-size FAPbI3 perovskite thin films and their perovskite solar cells. To facilitate a thorough understanding, the laboratory humidity conditions of this invention are greater than 70%. The main steps include:
[0047] Step 1) The etched FTO conductive glass was ultrasonically treated in ethanol, ultrapure water with cleaning agent, ultrapure water, and ethanol for 15 minutes each. After being dried with nitrogen, it was placed in a 100°C oven for 30 minutes to obtain a clean FTO substrate.
[0048] Step 2) Weigh 775.2 mg of lead iodide, 264.8 mg of formamidine, and 373.2 mg of formamidine chloride additive (30% by mass) in a ratio of 1.2:1. Dissolve them in 1 mL of a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide in a ratio of 8:1, and stir at -10°C for 3 hours until completely dissolved to prepare a perovskite precursor solution with a concentration of 1100 mg / mL.
[0049] Step 3) Dissolve 73.2 mg of Spiro-OMeTAD in 1 mL of chlorobenzene; dissolve 520 mg of lithium bis(trifluoromethanesulfonate)imide in 1 mL of acetonitrile solution; add 28.8 μL of TBP solution to the Spiro-OMeTAD solution and 17.6 μL of lithium salt solution to the Spiro-OMeTAD solution; stir the mixture at room temperature for 2 hours; spin-coating conditions are 2500 rpm for 30 seconds.
[0050] Step 4) Dissolve 5 mg of butylamine hydroiodide in 1 mL of isopropanol solution; stir the prepared butylamine hydroiodide solution at room temperature and 400 rpm for 1 hour.
[0051] Step 5) Treat the cleaned FTO substrate with ultraviolet ozone for 15 minutes.
[0052] Step 6) Take 40 μL of electron transport material SnO2 and drop it onto the FTO substrate treated in Step 4). Spin coat the substrate with a spin coater at 4000 rpm for 30 seconds. Then anneal the FTO substrate with SnO2 at 150°C for 30 minutes.
[0053] Step 7) Take 45 μL of the perovskite precursor solution prepared in Step 2) and drop it onto the FTO substrate cooled to -10℃ in Step 6), spin-coat it to form a film, and then anneal it to form a perovskite thin film. The spin-coating conditions are: 1000 rpm for 10 seconds, then 5000 rpm for 30 seconds, and 400 μL of diethyl ether at -10℃ is added as an anti-solvent at 5000 rpm for 10 seconds. After spin-coating, anneal it on a hot plate at 155℃ for 10 minutes.
[0054] Step 8) Spin-coat the butylamine hydroiodide interface modification material from step 4) onto the perovskite film from step 7). Spin-coat the butylamine hydroiodide interface modification material at 4000 rpm for 30 seconds. After spin-coating, anneal on a hot plate at 60°C for 1 minute to form the butylamine hydroiodide interface modification layer.
[0055] Step 9) Spin-coat the hole transport material from Step 3) onto the perovskite film modified with butylamine hydroiodide in Step 8). Spin-coat Spiro-OMeTAD at 2500 rpm for 30 seconds to form a hole transport layer.
[0056] Step 10) Using vacuum evaporation technology, 5 nm MoO3 is deposited on the hole transport layer in step 9), and then 100 nm metal electrode Ag is deposited to obtain a perovskite solar cell.
[0057] Step 11) Under standard test conditions (AM1.5 G illumination), the optimal battery device prepared in this example has a power conversion efficiency of 23.62%, an open-circuit voltage of 1.11V, and a short-circuit current of 25.97mA / cm². 2 The fill factor is 82.28%.
[0058] Example 2
[0059] This embodiment describes the process of controlling the phase formation temperature between the perovskite precursor solution and the mesophase to obtain large-grain-size FAPbI3 perovskite thin films and their perovskite solar cells. To facilitate a thorough understanding, the laboratory humidity conditions of this invention are greater than 70%. The main steps include:
[0060] Step 1) The etched FTO conductive glass was ultrasonically treated in ethanol, ultrapure water with cleaning agent, ultrapure water, and ethanol for 15 minutes each. After being dried with nitrogen, it was placed in a 100°C oven for 30 minutes to obtain a clean FTO substrate.
[0061] Step 2) Weigh 775.2 mg of lead iodide, 264.8 mg of formamidine, and 373.2 mg of formamidine chloride additive (30% by mass) in a ratio of 1.2:1. Dissolve them in 1 mL of a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide in a ratio of 8:1. Stir at -15°C for 3 hours until completely dissolved to prepare a perovskite precursor solution with a concentration of 1100 mg / mL.
[0062] Step 3) Dissolve 73.2 mg of Spiro-OMeTAD in 1 mL of chlorobenzene; dissolve 520 mg of lithium bis(trifluoromethanesulfonate)imide in 1 mL of acetonitrile solution; add 28.8 μL of TBP solution to the Spiro-OMeTAD solution and 17.6 μL of lithium salt solution to the Spiro-OMeTAD solution; stir the mixture at room temperature for 2 hours; spin-coating conditions are 2500 rpm for 30 seconds.
[0063] Step 4) Dissolve 5 mg of butylamine hydroiodide in 1 mL of isopropanol solution; stir the prepared butylamine hydroiodide solution at room temperature and 400 rpm for 1 hour.
[0064] Step 5) Treat the cleaned FTO substrate with ultraviolet ozone for 15 minutes.
[0065] Step 6) Take 40 μL of electron transport material SnO2 and drop it onto the FTO substrate treated in Step 4). Spin coat the substrate with a spin coater at 4000 rpm for 30 seconds. Then anneal the FTO substrate with SnO2 at 150°C for 30 minutes.
[0066] Step 7) Take 45 μL of the perovskite precursor solution prepared in Step 2) and drop it onto the FTO substrate cooled to -15℃ in Step 6), spin-coat it to form a film, and then anneal it to form a perovskite thin film. The spin-coating conditions are: 1000 rpm for 10 seconds, then 5000 rpm for 30 seconds, and 400 μL of diethyl ether at -15℃ is added as an anti-solvent at 5000 rpm for 10 seconds. After spin-coating, anneal it on a hot plate at 155℃ for 10 minutes.
[0067] Step 8) Spin-coat the butylamine hydroiodide interface modification material from step 4) onto the perovskite film from step 7). Spin-coat the butylamine hydroiodide interface modification material at 4000 rpm for 30 seconds. After spin-coating, anneal on a hot plate at 60°C for 1 minute to form the butylamine hydroiodide interface modification layer.
[0068] Step 9) Spin-coat the hole transport material from Step 3) onto the perovskite film modified with butylamine hydroiodide in Step 8). Spin-coat Spiro-OMeTAD at 2500 rpm for 30 seconds to form a hole transport layer.
[0069] Step 10) Using vacuum evaporation technology, 5 nm MoO3 is deposited on the hole transport layer in step 9), and then 100 nm metal electrode Ag is deposited to obtain a perovskite solar cell.
[0070] Step 11) Under standard test conditions (AM1.5 G illumination), the optimal battery device prepared in this example has a power conversion efficiency of 24.50%, an open-circuit voltage of 1.12V, and a short-circuit current of 25.88mA / cm². 2 The fill factor is 83.68%.
[0071] Example 3
[0072] This embodiment describes the process of controlling the phase formation temperature between the perovskite precursor solution and the mesophase to obtain large-grain-size FAPbI3 perovskite thin films and their perovskite solar cells. To facilitate a thorough understanding, the laboratory humidity conditions of this invention are greater than 70%. The main steps include:
[0073] Step 1) The etched FTO conductive glass was ultrasonically treated in ethanol, ultrapure water with cleaning agent, ultrapure water, and ethanol for 15 minutes each. After being dried with nitrogen, it was placed in a 100°C oven for 30 minutes to obtain a clean FTO substrate.
[0074] Step 2) Weigh 775.2 mg of lead iodide, 264.8 mg of formamidine, and 373.2 mg of formamidine chloride additive (30% by mass) in a ratio of 1.2:1. Dissolve them in 1 mL of a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide in a ratio of 8:1, and stir at -20°C for 3 hours until completely dissolved to prepare a perovskite precursor solution with a concentration of 1100 mg / mL.
[0075] Step 3) Dissolve 73.2 mg of Spiro-OMeTAD in 1 mL of chlorobenzene; dissolve 520 mg of lithium bis(trifluoromethanesulfonate)imide in 1 mL of acetonitrile solution; add 28.8 μL of TBP solution to the Spiro-OMeTAD solution and 17.6 μL of lithium salt solution to the Spiro-OMeTAD solution; stir the mixture at room temperature for 2 hours; spin-coating conditions are 2500 rpm for 30 seconds.
[0076] Step 4) Dissolve 5 mg of butylamine hydroiodide in 1 mL of isopropanol solution; stir the prepared butylamine hydroiodide solution at room temperature and 400 rpm for 1 hour.
[0077] Step 5) Treat the cleaned FTO substrate with ultraviolet ozone for 15 minutes.
[0078] Step 6) Take 40 μL of electron transport material SnO2 and drop it onto the FTO substrate treated in Step 4). Spin coat the substrate with a spin coater at 4000 rpm for 30 seconds. Then anneal the FTO substrate with SnO2 at 150°C for 30 minutes.
[0079] Step 7) Take 45 μL of the perovskite precursor solution prepared in Step 2) and drop it onto the FTO substrate cooled to -20℃ in Step 6), spin-coat it to form a film, and then anneal it to form a perovskite thin film. The spin-coating conditions are: 1000 rpm for 10 seconds, then 5000 rpm for 30 seconds, and 400 μL of diethyl ether at -20℃ is added as an anti-solvent at 5000 rpm for 10 seconds. After spin-coating, anneal it on a hot plate at 155℃ for 10 minutes.
[0080] Step 8) Spin-coat the butylamine hydroiodide interface modification material from step 4) onto the perovskite film from step 7). Spin-coat the butylamine hydroiodide interface modification material at 4000 rpm for 30 seconds. After spin-coating, anneal on a hot plate at 60°C for 1 minute to form the butylamine hydroiodide interface modification layer.
[0081] Step 9) Spin-coat the hole transport material from Step 3) onto the perovskite film modified with butylamine hydroiodide in Step 8). Spin-coat Spiro-OMeTAD at 2500 rpm for 30 seconds to form a hole transport layer.
[0082] Step 10) Using vacuum evaporation technology, 5 nm MoO3 is deposited on the hole transport layer in step 9), and then 100 nm metal electrode Ag is deposited to obtain a perovskite solar cell.
[0083] Step 11) Under standard test conditions (AM1.5 G illumination), the optimal battery device prepared in this example has a power conversion efficiency of 24.78%, an open-circuit voltage of 1.15V, and a short-circuit current of 26.08mA / cm². 2 The fill factor is 82.34%.
[0084] Comparative Example 1
[0085] Formamidinium-based perovskite solar cells were prepared by heating the precursor solution at 60°C and then reacting the substrate with the antisolvent at room temperature. The resulting thin film had small grain size, many pores, and an uneven surface. The energy conversion efficiency of the device prepared by this method was only 22.01%.
[0086] Comparative Example 2
[0087] Formamidinium-based perovskite solar cells were prepared using a precursor solution at room temperature (approximately 20°C), a substrate, and an antisolvent. The resulting thin film had medium-sized grains and numerous pores, but the energy conversion efficiency of the device prepared by this method was only 22.57%.
[0088] Comparative Example 3
[0089] Formamidinium-based perovskite solar cells were prepared by using a precursor solution at 0°C, a substrate, and an antisolvent. The resulting thin film had a relatively large grain size and a smooth surface, but still contained many pores. The energy conversion efficiency of the device prepared by this method was 23.19%.
[0090] In summary, this invention utilizes a low-temperature FAPbI3 perovskite precursor solution solvent to control the crystallization process by regulating the temperature of the precursor solvent and the intermediate phase, thereby preparing high-efficiency FAPbI3 perovskite thin films and solar cells. The prepared perovskite thin films have micron-sized dimensions and a dense, smooth morphology, and the prepared perovskite devices exhibit excellent device efficiency. The FAPbI3 perovskite solar cells prepared by this method are stable, have high photoelectric conversion efficiency, and possess significant advantages for industrialization.
[0091] The present invention is not limited to the specific technical solutions described in the above embodiments. All technical solutions formed by equivalent substitutions are within the scope of protection claimed by the present invention.
Claims
1. A method for preparing high-efficiency and stable formamidinium-based perovskite solar cells using a low-temperature process, characterized in that: Includes the following steps: (1) Dissolve lead iodide, formamidine iodide, and additive methylamine chloride in a molar ratio of 1.1:1:0.3 in a mixed solution of N,N-dimethylformamide solvent and dimethyl sulfoxide in a volume ratio of 8:1 to prepare a FAPbI3 perovskite precursor solution. Stir and dissolve the solution in an environment of -10°C to -20°C for 1 to 3 hours. (2) Electron transport material is spin-coated onto a cleaned and treated FTO transparent conductive glass sheet; (3) In an anhydrous and oxygen-free glove box, the prepared low-temperature perovskite precursor solution is spin-coated onto an FTO conductive substrate with an electron transport layer cooled to -10°C to -20°C, and diethyl ether, an antisolvent cooled to -10°C to -20°C, is added to obtain an intermediate phase film. (4) After annealing at 155°C for 10 minutes, a smooth and dense perovskite film is obtained. (5) A solution of butylamine hydroiodide was spin-coated onto the perovskite layer for post-treatment; (6) Spin-coating a hole transport layer onto the perovskite layer; (7) Vacuum evaporation of interface modification layer and metal electrode on hole transport layer.
2. The method for preparing high-efficiency and stable formamidinium-based perovskite solar cells using a low-temperature process according to claim 1, characterized in that: In step (1), the concentration of the FAPbI3 perovskite precursor solution is 900-1300 mg / mL.
3. The method for preparing high-efficiency and stable formamidinium-based perovskite solar cells using a low-temperature process according to claim 1, characterized in that: In step (2), the electron transport layer on the transparent conductive FTO glass is SnO2, and the specific steps are as follows: (1) The spin coating conditions are 4000 rpm for 30 seconds. (2) After spin coating, anneal at 150°C for 30 minutes.
4. The method for preparing high-efficiency and stable formamidinium-based perovskite solar cells using a low-temperature process according to claim 1, characterized in that: The thin film preparation in step (3) is carried out by spin coating and annealing in an anhydrous and oxygen-free glove box. The specific steps are as follows: (1) The spin coating conditions are: spin coating at 1000 rpm for 10 seconds, followed by spin coating at 5000 rpm for 30 seconds. (2) Before spin coating, the FTO glass coated with SnO2 electron transport layer is cooled to -10℃ to -20℃. (3) After spin coating at 5000 rpm for 10 s, add 400 μL of diethyl ether at -10℃ to -20℃ as an antisolvent. (4) After spin coating, anneal on a hot plate at 155°C for 10 minutes.
5. The method for preparing high-efficiency and stable formamidinium-based perovskite solar cells using a low-temperature process according to claim 1, characterized in that: The hole transport layer deposited in step (6) is Spiro-OMeTAD; the specific steps are as follows: (1) Dissolve 73.2 mg of Spiro-OMeTAD in 1 mL of chlorobenzene; (2) Dissolve 520 mg of lithium bis(trifluoromethanesulfonate)imide in 1 mL of acetonitrile solution; (3) Add 28.8 μL of TBP solution to Spiro-OMeTAD solution; (4) Add 17.6 μL of lithium salt solution to Spiro-OMeTAD solution; (5) Stir the mixed solution at room temperature for 2 hours; (6) Spin coating conditions are 2500 rpm for 30 seconds.
6. The method for preparing high-efficiency and stable formamidinium-based perovskite solar cells using a low-temperature process according to claim 1, characterized in that: In step (7), the interface modification layer is MoO3, and the metal electrode is Ag; the specific steps are as follows: (1) MoO3 was deposited on the hole transport layer with a thickness of 5 nm; (2) The thickness of the metal Ag electrode is 100 nm.
7. FAPbI3 perovskite solar cells prepared by the method according to any one of claims 1-6.
8. The application of the FAPbI3 perovskite solar cell according to claim 7 in the field of optoelectronics.