A method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells

Abstract

The application discloses a method for optimizing photoelectric performance of a CsPbIBr2 full-inorganic perovskite solar cell, and comprises the following steps: (1) cleaning and ultraviolet ozone treating an FTO substrate; (2) spin-coating an electron transport layer substrate on the cleaned and ultraviolet ozone treated FTO substrate, and then performing heat treatment in air; (3) spin-coating to prepare a CsPbIBr2 inorganic perovskite film on the surface of the dense electron transport layer substrate obtained in the step (2); (4) preparing a C electrode: transferring the CsPbIBr2 inorganic perovskite film obtained in the step (3) to air with a humidity RH of less than or equal to 40%, then spin-coating conductive carbon paste, and then performing low-temperature annealing; and (5) placing the device after the C electrode is prepared in the step (4) in air with a relative humidity of 10-60% to perform heat treatment, so that the photoelectric performance is optimized. According to the application, other chemical reagents are not needed, only O2 in the air is consumed, and the V oc , FF and PCE of the full-inorganic perovskite solar cell can be significantly and stably improved on the basis of the original efficiency.

Description

Technical Field

[0001] This invention relates to a method for fabricating an all-inorganic perovskite solar cell, and more particularly to a method for optimizing the photoelectric performance of a CsPbIBr2 all-inorganic perovskite solar cell through humidity heat treatment. Background Technology

[0002] All-inorganic perovskite solar cells have attracted much attention due to their balance of photoelectric conversion efficiency, stability, and cost. To date, the highest photoelectric conversion efficiency of this system (CsPbX3) has reached 21.35% (CsPbI3). As an inorganic system with a relatively large bandgap, it can not only achieve a high open-circuit voltage but also serve as a stable wide-bandgap solar cell in tandem cells. However, inorganic perovskite solar cells also face problems such as unstable active phase in the perovskite layer, inhomogeneity of the perovskite film, and high surface defect density, resulting in a significant gap compared to organic-inorganic hybrid perovskite solar cells. Furthermore, CsPbI3 perovskite solar cells are highly susceptible to humidity, transforming from the black α-CsPbI3 phase to the yellow δ-CsPbI3 phase. In contrast, inorganic CsPbIBr2 perovskite solar cells theoretically possess both high efficiency and stability, remaining stable even at relative humidity below 40%. The CsPbIBr2 film does not undergo a phase transition after more than one year of dark storage, and the device retains 97.8% of its initial efficiency after 180 days of storage. The biggest challenge currently lies in preparing uniform, high-quality CsPbIBr2 films with low defect density.

[0003] Currently, researchers typically improve the performance of CsPbIBr2 inorganic perovskite solar cells through techniques such as interface modification, component regulation, and solvent adjustment. However, these methods all require the addition of modifying materials, resulting in poor reproducibility. Therefore, how to stably and effectively optimize the performance of CsPbIBr2 inorganic perovskite solar cells using low-cost materials, or by utilizing materials inherent in the environment that do not require any extraction, is a pressing issue in this field. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells. Using this method, no other chemical reagents need to be added, only O2 in the air is consumed, which can significantly and stably improve the Voc, FF and photoelectric conversion efficiency (PCE) of the all-inorganic perovskite solar cells while maintaining the original efficiency.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells includes the following steps:

[0007] (1) Cleaning and UV ozone treatment of FTO substrate: The FTO substrate was ultrasonically cleaned in sequence with a mixture of detergent and deionized water, deionized water, and anhydrous ethanol, then dried and treated with UV ozone for later use.

[0008] (2) Preparation of dense electron transport layer substrate: The electron transport layer substrate is spin-coated on the FTO substrate that has been cleaned and treated with ultraviolet ozone in step (1), and then placed in air for heat treatment to obtain dense electron transport layer substrate.

[0009] (3) Spin-coating preparation of CsPbIBr2 inorganic perovskite film: The dense electron transport layer substrate obtained in step (2) is subjected to ultraviolet ozone treatment, and then CsPbIBr2 inorganic perovskite film is prepared by spin-coating on its surface. Then, it is annealed to obtain CsPbIBr2 inorganic perovskite film; the spin-coating precursor solution for preparing CsPbIBr2 inorganic perovskite film is a mixed dimethyl sulfoxide solution of CsI and PbBr2.

[0010] (4) Preparation of C electrode by scraping: The CsPbIBr2 inorganic perovskite film obtained in step (3) is transferred to air with a humidity RH≤40% (the humidity of C electrode preparation is controlled below 40% in order to prevent the phase change of CsPbIBr2 film), and then conductive carbon paste is scraped and then low-temperature annealing is performed to prepare C electrode, and the device with C electrode preparation is obtained.

[0011] (5) Heat treatment of the device after C-electrode fabrication: The device with C-electrode fabrication obtained in step (4) is placed in air with a relative humidity of 10% to 60% for heat treatment to obtain a CsPbIBr2 all-inorganic perovskite solar cell with optimized photoelectric performance. Using this invention, the Vt of the CsPbIBr2 inorganic perovskite solar cell device can be stably improved. oc The addition of FF (Fluorescent Fluorescent) technology increased its photoelectric conversion efficiency from 3.85% to 6.91%, laying the technological foundation for the development and application of water-oxygen optimized inorganic perovskite solar cells.

[0012] Furthermore, in step (1), the ultrasonic cleaning time is 10-20 min, preferably 12-18 min, more preferably 14-16 min, and even more preferably 15 min.

[0013] Furthermore, in step (1), the drying temperature is 80-100°C, preferably 90-95°C, and more preferably 100°C.

[0014] Furthermore, in step (1), after ultrasonic cleaning with anhydrous ethanol, the substrate can be ultrasonically cleaned with isopropanol for 10-20 minutes, preferably 12-18 minutes, more preferably 14-16 minutes, and even more preferably 15 minutes. By adopting the above technical solution, the FTO substrate can be cleaned more thoroughly.

[0015] Furthermore, in step (2), the electron transport layer is a TiO2 or SnO2 electron transport layer.

[0016] For the TiO2 electron transport layer:

[0017] Furthermore, in step (2), the ethanol solution of tetraisopropyl titanate is prepared by mixing and stirring 0.5M tetraisopropyl titanate and 0.5M diethanolamine ethanol solution for more than 24 hours, and then filtering it with a 0.25μm filter head for later use.

[0018] Furthermore, in step (2), the preparation of the ethanol solution of tetraisopropyl titanate is completed in a glove box under N2 atmosphere.

[0019] For the SnO2 electron transport layer:

[0020] Further, in step (2), the SnO2 electron transport layer is spin-coated with a 50mM SnCl4·5H2O isopropanol solution at 3000rpm for 30s, heat-treated at 100℃ for 10min, and then heat-treated at 180℃ for 1h.

[0021] Furthermore, in step (2), the amount of SnCl4·5H2O isopropanol solution used is 50-100 μL, preferably 65-80 μL, and more preferably 70 μL.

[0022] Furthermore, in step (2), the SnO2 layer prepared by spin-coating SnCl4·5H2O isopropanol solution was immersed in 10mM SnCl2·2H2O solution at 70℃ for 1h, then ultrasonicated for 2min, heat-treated at 100℃ for 10min and then heat-treated at 180℃ for 1h.

[0023] Furthermore, in step (2), the SnO2 electron transport layer is prepared in air.

[0024] Furthermore, in step (2), the spin coating speed is 500-8000 rpm, preferably 1000-7500 rpm, more preferably 7000 rpm, and the spin coating time is 10-30 s.

[0025] Furthermore, in step (2), the temperature of the heat treatment is 400-500℃, preferably 450℃; and the time of the heat treatment is 45-90min, preferably 60min.

[0026] Furthermore, in step (2), the heat treatment needs to be based on the standard that the TiO2 electron transport layer is colorless and transparent.

[0027] Furthermore, in step (2), the heat treatment needs to be based on the standard that the SnO2 electron transport layer is colorless and transparent and the surface is free of impurity particles.

[0028] By adopting the above technical solution, the prepared TiO2 or SnO2 electron transport layer has better conductivity.

[0029] Furthermore, in step (3), the precursor solution of CsPbIBr2 is CsI and PbBr2 dissolved in dimethyl sulfoxide (DMSO) at a molar ratio of 1:1.

[0030] Furthermore, in step (3), the precursor solution of CsPbIBr2 consists of 260 mg CsI and 367 mg PbBr2 dissolved in 1 mL dimethyl sulfoxide (DMSO).

[0031] Furthermore, in step (3), 3-5 mg / mL of PbI2 is added to the precursor solution of CsPbIBr2 to optimize device performance.

[0032] Furthermore, in step (3), the precursor solution of CsPbIBr2 is stirred at 40-60°C for 1-3 hours and then filtered with a filter head with a pore size of 0.25 μm.

[0033] Further, in step (3), the spin coating of the CsPbIBr2 film is first spin-coated at 1000-2000 rpm for 10-20 s, and then spin-coated at 3000-6000 rpm for 30-60 s, preferably first spin-coated at 1500 rpm for 15 s, and then spin-coated at 5000 rpm for 30 s.

[0034] Furthermore, in step (3), the annealing is first annealing at 10-50°C for 1-3 minutes, and then annealing at 200-300°C for 5-10 minutes, preferably first annealing at 30°C for 1 minute, and then annealing at 280°C for 5 minutes.

[0035] The optimal temperature for the low-temperature annealing step is when the film becomes a uniform, transparent, light yellow film.

[0036] Furthermore, in step (3), the ultraviolet ozone treatment time is 10 to 20 minutes, preferably 15 minutes.

[0037] By adopting the above technical solution, the V2 of the CsPbIBr2 all-inorganic perovskite solar cell is improved. oc FF and PCE are higher.

[0038] Furthermore, in step (4), the C slurry is pre-cured. If the slurry is too thin, the FF of the device will be reduced. An ohmic contact needs to be formed between C and CsPbIBr2.

[0039] Furthermore, in step (4), the heat treatment method is to heat treat at 80-120℃ for 10-30 minutes, preferably at 100℃ for 20 minutes.

[0040] By adopting the above technical solution, the FF of C-based CsPbIBr2 perovskite solar cells is higher.

[0041] Furthermore, in step (5), the temperature of the heat treatment is 120-160°C, preferably 145-155°C, and more preferably 150°C; the time of the heat treatment is 30-200 min, preferably 150-185 min, and more preferably 190 min. The lower the temperature, the longer the heat treatment time needs to be.

[0042] Furthermore, in step (5), the humidity (RH) of the air is preferably 20% to 50%, more preferably 30% to 40%. Higher humidity tends to increase the device's humidity (V). oc The higher the humidity, the more likely the device's FF will increase, reflecting the influence of humidity on the reaction mechanism.

[0043] Through the above technical solution, after the completion of the C-based CsPbIBr2 perovskite solar cell device in this invention, heating at 120℃~160℃ for 30-200min in air with RH≤60% utilizes the humidity and oxygen in the air. No other optimization steps need to be inserted during the device fabrication process. The heat treatment treats the cell as a whole, performing defect passivation at the interface and grain boundaries and bandgap coupling of the device, exhibiting extremely high repeatability in the CsPbIBr2 system. Furthermore, this invention also allows CsPbIBr2 thin films that have lost photoelectric activity due to phase transitions caused by exposure to humidity to regain photoelectric activity. This invention optimizes the photoelectric performance of C-based CsPbIBr2 devices without using any additives, relying solely on humid air and heating.

[0044] The principle of this invention is as follows: When an inorganic CsPbIBr2 perovskite thin film is heated in air, it undergoes the following two reactions with O2: (1) CsPbIBr2 reacts with O2 to generate CsPbBr3, PbO, I2 and CsBr; (2) O2 passivates uncoordinated Pb defects in the film to form PbO. In low-humidity air, heat treatment reaction (1) is the main reaction. The role of humidity is to confine the two reactions to the grain boundaries and interfaces, while controlling reaction (2) to proceed slowly and orderly. In the product, CsPbBr3 and CsPbIBr2 undergo band coupling, which is beneficial to the transport of charge carriers in the device. The passivation of defects by reaction (1) can suppress nonradiative recombination inside the film, thereby improving the FF and V of the device. oc When humidity increases or heat treatment temperature rises, both reactions intensify rapidly, and the device's V... oc FF and PCE reach their peak values, but with the accumulation of products CsPbBr3, CsBr, and PbO, carrier transport in the thin film is suppressed, and the device's V... oc Continuously improve and J sc FF and PCE continue to decrease.

[0045] This invention employs a humidity-controlled heat treatment technique: after the CsPbIBr2 perovskite solar cell is fabricated, the humidity, temperature, and time of the heat treatment are precisely controlled. Lower humidity and temperature result in slow optimization, while higher humidity and temperature lead to rapid reactions and gradually cause a decline in device efficiency. Maintaining humidity within the RH range of 10-40% allows for an optimization window exceeding 3 hours, while reaching RH 60% requires only 1 hour, but the optimization effect is less than the former.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) This invention does not require the addition of other chemical reagents, and only consumes O2 from the air; (2) This invention significantly and stably improves the VE of the already prepared C-based perovskite solar cell within a certain range, based on the original efficiency. oc The study of FF and PCE provides insights for low-cost optimization of CsPbBr2 all-inorganic perovskite solar cells. Detailed Implementation

[0048] To facilitate understanding of the present invention, the present invention will be further described below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0049] The technical terms used below are for the purpose of describing specific embodiments only, and unless otherwise defined, all technical terms used have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, all reagents and raw materials used in this invention are commercially available or prepared by methods disclosed in existing literature.

[0050] The device (CsPbIBr2 all-inorganic perovskite solar cell) described in the following examples was fabricated using the following method:

[0051] (1) Cleaning the FTO substrate: Using a 2.5cm×2.5cm FTO transparent glass substrate, ultrasonically clean it for 15 minutes in sequence with a mixture of glass detergent and deionized water, deionized water and anhydrous ethanol, then bake it at 80℃ for 10 minutes; after UV ozone treatment for 15 minutes, it is ready for use.

[0052] (2) Preparation of electron transport layer substrate: This is described in detail in each of Examples 1 to 5;

[0053] (3) Spin-coating preparation of CsPbIBr2 inorganic perovskite film: The dense electron transport layer substrate obtained in step (2) was treated with ultraviolet ozone for 15 min, and then transferred to a glove box with N2 atmosphere. The 1M CsPbIBr2 perovskite precursor solution (260 mg CsI and 367 mg dissolved in 1 mL DMSO) was first spin-coated at 1500 rpm for 15 s, and then spin-coated at 5000 rpm for 30 s to obtain a perovskite wet film. The perovskite wet film was first annealed at 30 °C for 1 min, and then annealed at 280 °C for 5 min to obtain CsPbIBr2 inorganic perovskite film.

[0054] (4) Preparation of C electrode by scraping: The CsPbIBr2 inorganic perovskite film obtained in step (3) is transferred to air with humidity (RH≤40%), and conductive carbon paste is scraped and cured by low temperature annealing at 100℃ for 20min to form C electrode; the device with C electrode preparation is obtained.

[0055] (5) Humidity heat treatment of the device after C electrode preparation: The device after C electrode preparation obtained in step (4) is placed in air with a humidity of 20% to 60% and subjected to heat treatment at 150°C for a gradient time of 0-190 min. The specific operation is described in detail in Examples 1 to 5 below.

[0056] Example 1

[0057] This embodiment optimizes the photoelectric performance of a CsPbIBr2 inorganic perovskite solar cell based on a TiO2 electron transport layer through heat treatment at 120°C in humid air.

[0058] Steps (1), (3) and (4) are completed according to the above process;

[0059] Step (2) to prepare a dense TiO2 electron transport layer substrate is as follows: In a glove box under N2 atmosphere, an ethanol solution containing 0.5M tetraisopropyl titanate and 0.5M diethanolamine is prepared, stirred for 24 hours, and then filtered with a 0.25μm filter head; then spin-coated at 7000rpm onto the FTO substrate obtained in step (1) (completed in 30s). After spin-coating, the substrate is transferred to air and heated at 450℃ for 60min until the TiO2 electron transport layer is colorless and transparent;

[0060] Step (5): Transfer the device obtained in step (4) to air with a humidity of 20% ≤ RH ≤ 30%, heat-treat at 100℃ for 60 min, and then test the photoelectric performance of the device. The test conditions are room temperature, RH < 30%, AM 1.5 (100mW / cm²). 2 The effective area is the area of ​​the aperture of the template, which is 0.075 cm². 2 Calibration.

[0061] Test results: Heat treatment at 100℃ for 60 minutes increased PCE from 2.34% to 2.52%, a slight improvement.

[0062] Example 2

[0063] This embodiment optimizes the photoelectric performance of a CsPbIBr2 inorganic perovskite solar cell based on a TiO2 electron transport layer through heat treatment at 150°C in humid air. The differences from Embodiment 1 are the heat treatment time and the initial device efficiency.

[0064] Steps (1) to (4) should be completed according to the above process;

[0065] Step (5): Transfer the device obtained in step (4) to air with a humidity of 20% ≤ RH ≤ 30%, and heat-treat it at 150℃ for 0 min, 60 min, 120 min, 160 min, and 190 min respectively, and test the photoelectric conversion efficiency of the device. The test conditions are room temperature, RH < 30%, AM 1.5 (100mW / cm²). 2 The effective area is the area of ​​the aperture of the template, which is 0.075 cm². 2 Calibration.

[0066] The test results are shown in Table 1. The initial efficiency of the TiO2-based CsPbIBr2 all-inorganic perovskite solar cell was 3.85%. After heat treatment at 150℃ for 190 min, the efficiency increased to 6.91%, the open-circuit voltage increased from 1.085V to 1.284V, and the fill factor increased from 47.10% to 70.95%, demonstrating strong stability.

[0067] Table 1. Changes in photoelectric performance parameters of TiO2-based devices during low-humidity heat treatment at 150℃.

[0068]

[0069] Example 3

[0070] This embodiment demonstrates the optimization of the photoelectric performance of a CsPbIBr2 inorganic perovskite solar cell based on a SnO2 electron transport layer through heat treatment at 150°C in humid air, confirming the same optimization effect of the present invention in different electron transport layers.

[0071] Steps (1), (3) and (4) are completed according to the above process;

[0072] Step (2) Preparation of a dense SnO2 electron transport layer substrate: 70 μL of 50 mM SnCl4·5H2O isopropanol solution was spin-coated at 3000 rpm for 30 s, heat-treated at 100℃ for 10 min, and then heat-treated at 180℃ for 1 h. Then, the SnO2 layer was modified by chemical deposition. 10 mM SnCl2·2H2O, 40 mL of deionized water solution, 10 μL of mercaptoacetic acid, 0.5 mL of concentrated hydrochloric acid and 500 mg of urea were added and mixed to obtain a mixed solution. The SnO2 layer prepared by the SnCl4·5H2O isopropanol solution was treated with ultraviolet ozone for 15 min, then immersed in the above mixed solution at 70℃ for 1 h, ultrasonically cleaned with deionized water for 2 min, and then heat-treated at 100℃ for 10 min, and then heat-treated at 180℃ for 1 h.

[0073] Step (5): Transfer the device obtained in step (4) to air with a humidity of 20% ≤ RH ≤ 30%, and heat-treat it at 150℃ for 0 min, 60 min, 120 min, and 150 min respectively. Test the photoelectric conversion efficiency of the device. The test conditions are room temperature, RH < 30%, AM 1.5 (100mW / cm²). 2 The effective area is the area of ​​the aperture of the template, which is 0.075 cm². 2 Calibration.

[0074] The test results are shown in Table 2. The initial efficiency of the SnO2-based CsPbIBr2 inorganic perovskite solar cell was 7.01%. After heat treatment at 150℃ for 120 min, the efficiency increased to 7.62%, the open-circuit voltage increased from 1.253V to 1.281V, and the fill factor increased from 61.35% to 70.44%, demonstrating strong stability and showcasing the optimization effect of this invention on the SnO2 electron transport layer.

[0075] Table 2. Changes in photoelectric performance parameters of SnO2-based devices during low-humidity heat treatment at 150℃.

[0076]

[0077] Example 4

[0078] This embodiment optimizes a CsPbIBr2 inorganic perovskite solar cell based on a SnO2 electron transport layer by heat treatment at 150°C in humid air. The difference from Embodiment 2 is the preparation method of the SnO2 electron transport layer and the humidity of the air during heat treatment. This confirms the optimization effect of the present invention under different humidity levels and on different substrates. Except for the different electron transport layer preparation method and heat treatment procedure, the other steps are the same.

[0079] Steps (1), (3) and (4) are completed according to the above process;

[0080] Step (2) to prepare a dense SnO2 electron transport layer substrate is as follows: 20mM SnCl2·2H2O, 40mL deionized water solution, 10μL mercaptoacetic acid, 0.5mL concentrated hydrochloric acid and 1000mg urea are added and mixed to obtain a mixed solution; then the FTO glass substrate obtained in step (1) is treated with ultraviolet ozone for 15min, soaked in the above mixed solution at 70℃ for 3h, ultrasonically cleaned for 2min, heat-treated at 100℃ for 10min, and then heat-treated at 180℃ for 1h.

[0081] Step (5): Transfer the device obtained in step (4) to low humidity air (20% ≤ RH ≤ 30%) and heat-treat at 150℃ for 30 min. Then transfer it to high humidity air (RH 60%) and heat-treat at 150℃ for 20 min. Test and record the photoelectric conversion efficiency of the device at 0 min, 30 min, and 50 min. Test conditions are room temperature, RH < 30%, AM 1.5 (100 mW / cm²). 2 The effective area is the area of ​​the aperture of the template, which is 0.075 cm². 2 Calibration.

[0082] The test results are shown in Table 3. The initial efficiency of the SnO2-based CsPbIBr2 perovskite solar cells prepared by different methods was 5.54%. After heat treatment in low-humidity air, the efficiency of the device increased to 7.29%, the open-circuit voltage increased from 1.104V to 1.111V, and the fill factor increased from 50.86% to 66.74%. After heat treatment in high-humidity air (RH>60%) for 20 minutes, the efficiency further increased to 8.03%, the open-circuit voltage further increased to 1.266V, and the fill factor decreased to 65.24%, further demonstrating the stable and effective optimization of CsPbIBr2 perovskite solar cells.

[0083] Table 3. Changes in photoelectric performance parameters of SnO2-based devices during heat treatment at 150℃ with different humidity levels.

[0084]

[0085] Example 5

[0086] This embodiment describes the repair of a phase-change-failed CsPbIBr2 all-inorganic perovskite solar cell by heat treatment at 150°C in low-humidity air. Unlike the four embodiments mentioned above, this embodiment focuses on a phase-change-failed CsPbIBr2 perovskite solar cell.

[0087] (1) Obtaining CsPbIBr2 perovskite solar cells: The devices obtained in step (4) of the above three embodiments were exposed to high humidity air with RH>80% to cause the CsPbIBr2 thin film to change to an inactive phase and completely lose its photoelectric activity.

[0088] (2) Transfer the phase-change failure device to a low humidity (RH<30%) 150℃ heat treatment for 30 min, and test and record the photoelectric conversion efficiency of the device.

[0089] The test conditions were room temperature, RH < 30%, AM 1.5 (100mW / cm²). 2 The effective area is the area of ​​the aperture of the template, which is 0.075 cm². 2 Calibration.

[0090] Test results: The photoelectric performance of the CsPbIBr2 all-inorganic perovskite solar cells that experienced phase transition failure has been restored to the level before the phase transition failure.

Claims

1. A method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells, characterized in that: Includes the following steps: (1) Cleaning and UV ozone treatment of FTO substrate: The FTO substrate was ultrasonically cleaned in sequence with a mixture of detergent and deionized water, deionized water, and anhydrous ethanol, then dried and treated with UV ozone for later use. (2) Preparation of dense electron transport layer substrate: The electron transport layer substrate is spin-coated on the FTO substrate that has been cleaned and treated with ultraviolet ozone in step (1), and then placed in air for heat treatment to obtain dense electron transport layer substrate. (3) Preparation of CsPbIBr2 inorganic perovskite film: The dense electron transport layer substrate obtained in step (2) is subjected to ultraviolet ozone treatment, and then CsPbIBr2 inorganic perovskite film is prepared by spin coating on its surface, and then annealed to obtain CsPbIBr2 inorganic perovskite film; the spin coating precursor solution for preparing CsPbIBr2 inorganic perovskite film is a mixed dimethyl sulfoxide solution of CsI and PbBr2; (4) Preparation of C electrode: The CsPbIBr2 inorganic perovskite film obtained in step (3) is transferred to air with a humidity of RH≤40%, and then conductive carbon paste is coated and then annealed at low temperature to obtain the C electrode, thus completing the preparation of the C electrode device. (5) Heat treatment of the device after C electrode preparation: The device after C electrode preparation in step (4) is placed in air with a relative humidity of 10%~60% for heat treatment to obtain CsPbIBr2 all-inorganic perovskite solar cell with optimized photoelectric performance.

2. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 1, characterized in that: In step (1), the ultrasonic cleaning time is 10~20 min; the drying temperature is 80~100 °C.

3. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 1 or 2, characterized in that: In step (2), the electron transport layer is a TiO2 or SnO2 electron transport layer.

4. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 3, characterized in that: In step (2), when the electron transport layer is a TiO2 electron transport layer, the specific operation method for spin-coating the electron transport layer is as follows: spin-coating an ethanol solution of tetraisopropyl titanate onto an FTO substrate that has been cleaned and treated with ultraviolet ozone in step (1). The ethanol solution of tetraisopropyl titanate is prepared by mixing and stirring 0.5 M tetraisopropyl titanate and 0.5 M diethanolamine in an ethanol solution for more than 24 hours. The preparation of the ethanol solution of tetraisopropyl titanate is completed in a glove box under N2 atmosphere.

5. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 1 or 2, characterized in that: In step (2), the temperature of the heat treatment is 400~500℃; the time of the heat treatment is 45~90min; the rotation speed of the spin coating is 500~1000rpm; and the spin coating time is 10~30s.

6. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 3, characterized in that: In step (2), the temperature of the heat treatment is 400~500℃; the time of the heat treatment is 45~90min; the rotation speed of the spin coating is 500~1000rpm; and the spin coating time is 10~30s.

7. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 4, characterized in that: In step (2), the temperature of the heat treatment is 400~500℃; the time of the heat treatment is 45~90min; the rotation speed of the spin coating is 500~1000rpm; and the spin coating time is 10~30s.

8. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 1 or 2, characterized in that: In step (3), the spin-coating precursor solution for preparing CsPbIBr2 inorganic perovskite thin films is prepared by dissolving CsI and PbBr2 in dimethyl sulfoxide at a molar ratio of 1:1; the preparation of the spin-coating precursor solution and spin-coating are both completed in a glove box under N2 atmosphere.

9. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 3, characterized in that: In step (3), the spin-coating precursor solution for preparing CsPbIBr2 inorganic perovskite thin films is prepared by dissolving CsI and PbBr2 in dimethyl sulfoxide at a molar ratio of 1:1; the preparation of the spin-coating precursor solution and spin-coating are both completed in a glove box under N2 atmosphere.

10. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 4, characterized in that: In step (3), the spin-coating precursor solution for preparing CsPbIBr2 inorganic perovskite thin films is prepared by dissolving CsI and PbBr2 in dimethyl sulfoxide at a molar ratio of 1:1; the preparation of the spin-coating precursor solution and spin-coating are both completed in a glove box under N2 atmosphere.

11. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 5, characterized in that: In step (3), the spin-coating precursor solution for preparing CsPbIBr2 inorganic perovskite thin films is prepared by dissolving CsI and PbBr2 in dimethyl sulfoxide at a molar ratio of 1:1; the preparation of the spin-coating precursor solution and spin-coating are both completed in a glove box under N2 atmosphere.

12. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 8, characterized in that: In step (3), 3~5 mg / mL PbI2 is added to the spin coating precursor solution.

13. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 1 or 2, characterized in that: In step (3), the annealing method is as follows: first anneal at 30~50℃ for 1~3 minutes, then anneal at 200~300℃ for 5~10 minutes.

14. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 3, characterized in that: In step (3), the annealing method is as follows: first anneal at 30~50℃ for 1~3 minutes, then anneal at 200~300℃ for 5~10 minutes.

15. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 4, characterized in that: In step (3), the annealing method is as follows: first anneal at 30~50℃ for 1~3 minutes, then anneal at 200~300℃ for 5~10 minutes.

16. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 5, characterized in that: In step (3), the annealing method is as follows: first anneal at 30~50℃ for 1~3 minutes, then anneal at 200~300℃ for 5~10 minutes.

17. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 8, characterized in that: In step (3), the annealing method is as follows: first anneal at 30~50℃ for 1~3 minutes, then anneal at 200~300℃ for 5~10 minutes.

18. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 12, characterized in that: In step (3), the annealing method is as follows: first anneal at 30~50℃ for 1~3 minutes, then anneal at 200~300℃ for 5~10 minutes.

19. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 1 or 2, characterized in that: In step (5), the heat treatment temperature is 120~160 °C and the time is 150~190 min.

20. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 3, characterized in that: In step (5), the heat treatment temperature is 120~160 °C and the time is 150~190 min.

21. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 4, characterized in that: In step (5), the heat treatment temperature is 120~160 °C and the time is 150~190 min.

22. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 5, characterized in that: In step (5), the heat treatment temperature is 120~160 °C and the time is 150~190 min.

23. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 8, characterized in that: In step (5), the heat treatment temperature is 120~160 °C and the time is 150~190 min.

24. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 12, characterized in that: In step (5), the heat treatment temperature is 120~160 °C and the time is 150~190 min.

25. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 13, characterized in that: In step (5), the heat treatment temperature is 120~160 °C and the time is 150~190 min.

26. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 1 or 2, characterized in that: In step (5), the relative humidity of the air is 20% to 60%.

27. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 3, characterized in that: In step (5), the relative humidity of the air is 20% to 60%.

28. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 4, characterized in that: In step (5), the relative humidity of the air is 20% to 60%.

29. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 5, characterized in that: In step (5), the relative humidity of the air is 20% to 60%.

30. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 8, characterized in that: In step (5), the relative humidity of the air is 20% to 60%.

31. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 12, characterized in that: In step (5), the relative humidity of the air is 20% to 60%.

32. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 13, characterized in that: In step (5), the relative humidity of the air is 20% to 60%.

33. The method for optimizing the photoelectric performance of CsPbIBr2 all-inorganic perovskite solar cells according to claim 19, characterized in that: In step (5), the relative humidity of the air is 20% to 60%.

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