Perovskite thin film, preparation process thereof and perovskite solar cell

Abstract

The application provides a perovskite thin film and a preparation process thereof and a perovskite solar cell, and belongs to the technical field of solar cells.The perovskite thin film comprises the following preparation steps: mixing, stirring, heating and ultrasonicating MXene powder, anhydrous dichloromethane and succinyl chloride, filtering and washing, mixing with anhydrous ethanol and performing suction filtration, and heating and drying to obtain a composite mesh; mixing, stirring, ultrasonicating and filtering 1-allyl-3-methyl imidazole iodide, 2-hydroxy-2-methyl-1-phenyl-1-propanone and anhydrous acetonitrile to obtain a buffer; laying the first piece of composite mesh on a substrate, performing hot pressing treatment, dropping the buffer and performing spin coating, irradiating with ultraviolet light, dropping a precursor solution and performing spin coating, laying the second piece of composite mesh, dropping ethyl acetate and performing spin coating, adjusting humidity, and heating and annealing to obtain the perovskite thin film.The perovskite thin film prepared by the application can improve the open-circuit voltage, the fill factor and the photoelectric conversion efficiency of the perovskite solar cell.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, specifically to a perovskite thin film, its preparation process, and a perovskite solar cell. Background Technology

[0002] Perovskite solar cells have attracted continuous attention in recent years due to their advantages such as high photoelectric conversion efficiency, simple solution-based fabrication process, and low cost. Among them, perovskite materials, represented by FAPbI3, are considered important light-absorbing materials for realizing high-efficiency perovskite solar cells due to their suitable band gap and excellent light absorption capacity. However, in the actual fabrication process of perovskite thin films, especially when heating and annealing are required under certain relative humidity conditions to promote phase transition and crystallinity, excessive lead iodide (PbI2) is easily generated in the perovskite thin film.

[0003] Excess PbI2 tends to accumulate, particularly at the interfaces between the electron transport layer and hole transport layer of perovskite thin films. Under sunlight, PbI2 readily decomposes to form elemental iodine (I2). This process not only accelerates the chemical degradation of perovskite materials but also, due to its strong diffusivity and oxidizing properties, I2 easily introduces electron traps at the electron transport layer interface, reducing electron extraction efficiency. Simultaneously, it may oxidize the hole transport layer material, increasing interfacial transport resistance, thus leading to a decrease in the open-circuit voltage, fill factor, and overall photoelectric conversion efficiency of perovskite solar cells. To suppress PbI2 formation and improve the crystallinity of perovskite thin films, existing technologies mainly focus on adjusting precursor formulations, introducing additives, or optimizing annealing processes. However, these methods largely concentrate on controlling the overall crystallization process of the perovskite thin film, lacking effective control over the local nucleation and growth behavior at the upper and lower interfaces.

[0004] For example, patent application CN118234352A discloses a perovskite precursor solution, a perovskite thin film, a preparation method thereof, and a solar cell. The perovskite precursor solution includes a perovskite complex and a composite solvent. The composite solvent comprises: a first solvent, including an amide solvent, with a molar ratio of the first solvent to the perovskite complex of 0.5–0.9:1; a second solvent, including at least one of a ketone solvent, an alcohol ether solvent, or an ester solvent, with a molar ratio of the second solvent to the perovskite complex of 0.1–0.5:1; and a third solvent, including a sulfoxide solvent, with a molar ratio of the third solvent to the perovskite complex of 0.001–0.1:1. This method reduces the accumulation of lead iodide and other substances on the film surface by using a combination of specific solvents, thereby improving the crystallinity of the perovskite. However, it relies solely on the solvent system to regulate crystallization kinetics and cannot effectively enhance regulation at the upper and lower interfaces of the perovskite thin film, thus limiting the improvement of the interface uniformity of the perovskite thin film.

[0005] In summary, there is a need to provide a perovskite thin film, its preparation process, and a perovskite solar cell to solve the problems existing in the prior art. Summary of the Invention

[0006] In view of this, the present invention provides a perovskite thin film and its preparation process, which improves the film uniformity of the perovskite thin film, thereby improving the open-circuit voltage and fill factor of the perovskite solar cell prepared therefrom, and thus improving the photoelectric conversion efficiency.

[0007] To achieve the above objectives, the present invention provides a process for preparing perovskite thin films, comprising the following preparation steps:

[0008] S1. Mix MXene powder and anhydrous dichloromethane, add succinyl chloride under nitrogen protection, heat, sonicate, filter, wash with anhydrous dichloromethane, mix the resulting particles with anhydrous ethanol, vacuum filter, heat and dry to obtain composite mesh.

[0009] S2. Mix and stir 1-allyl-3-methylimidazolium iodide, 2-hydroxy-2-methyl-1-phenyl-1-propanone and anhydrous acetonitrile, sonicate, filter to remove impurities, and obtain a buffer.

[0010] S3. Mix lead iodide, formamidinium hydroiodate, cesium iodide, methyl ammonium chloride, methyl ammonium bromide, and 4-hydrazinebenzenesulfonic acid, add urea, DMSO, and DMF, heat and stir, let stand and filter to obtain the precursor solution;

[0011] S4. Lay the first composite mesh on the substrate, heat and pressurize it, add a buffer, spin coat it, irradiate it with ultraviolet light, add a precursor solution, spin coat it in two stages to form a wet film, lay the second composite mesh, add ethyl acetate, spin coat it, adjust the relative humidity, heat and anneal it to obtain a perovskite thin film.

[0012] During the preparation of perovskite thin films, heating and annealing in an environment with a certain relative humidity are required to improve phase transformation and crystallization quality. However, the combined effect of humidity and heat treatment often induces excessive PbI2 formation in the perovskite film. Under sunlight, PbI2 decomposes into elemental iodine (I2), catalyzing the degradation of perovskite and increasing defects in the perovskite film, leading to a decrease in photoelectric conversion efficiency. This invention prepares a composite mesh with a sheet-like porous conductive network using MXene powder (titanium aluminum carbide powder) and succinyl chloride, embedding it into the bottom and top surfaces of a wet film. Succinyl chloride undergoes acylation grafting with MXene through the -COCl group. During annealing and crystallization, succinyl chloride migrates from the porous structure of the composite mesh into the interior of the wet film and enters the grain boundary regions between perovskite grains. Its carbonyl functional groups can interact with uncoordinated Pb at the grain boundaries. 2+Coordination reactions occur, filling grain boundary defects and passivating exposed surface sites, thus inhibiting PbI2 formation induced by moisture at grain boundaries. Simultaneously, the upper and lower composite meshes form a stable network barrier on the outside of the perovskite film, reducing the penetration depth of moisture along grain boundaries and improving the phase purity and structural stability of the film. After grain boundary passivation and moisture barrier treatment, the defect density of the perovskite film decreases, the diffusion length and migration efficiency of charge carriers in the film increase, and losses during electron and hole transport are reduced, improving the film uniformity of the perovskite film. This leads to an increase in the open-circuit voltage and fill factor of the fabricated perovskite solar cell, thereby enhancing the photoelectric conversion efficiency of the cell.

[0013] In this invention, a buffer is prepared by blending 1-allyl-3-methylimidazolium iodide and 2-hydroxy-2-methyl-1-phenyl-1-propanone, and then spin-coated onto a first composite mesh. After UV irradiation, the uniformity of the perovskite film formation is further improved. Under UV irradiation, 2-hydroxy-2-methyl-1-phenyl-1-propanone acts as a photoinitiator, promoting the cross-linking reaction of the unsaturated groups in 1-allyl-3-methylimidazolium iodide. This helps to confine the buffer to the surface of the composite mesh, preventing migration or loss during subsequent spin-coating and annealing. 1-allyl-3-methylimidazolium iodide exhibits good interfacial spreading properties, interacting with polar sites on the surface of the composite mesh through weak electrostatic and polar interactions, thereby improving the wetting and spreading of the precursor solution on the composite mesh surface and reducing localized accumulation. Simultaneously, in the initial stage of spin-coating the perovskite precursor solution to form a wet film, imidazole ions react with Pb in the precursor solution. 2+ and I - The reversible mutual adsorption behavior helps to balance the ion distribution in the interface region, slows down the abrupt change in the nucleation rate at the interface, and enables perovskite to nucleate more uniformly near the composite mesh, thereby improving the stability of the interfacial film formation process, further improving the film quality of perovskite films, and increasing the open-circuit voltage and fill factor of perovskite solar cells.

[0014] Optionally, after adjusting the relative humidity, a low-voltage DC current is applied between the substrate and the second composite mesh. The specific steps are as follows: an electrical clamp is used to establish an electrical connection with the substrate and the second composite mesh respectively, and a low-voltage DC current is applied for 5~10s; the current of the low-voltage DC current is 60~80mA and the voltage is 0.5~1V; the substrate includes a bottom electrode layer and an electron transport layer stacked sequentially.

[0015] In perovskite solar cells, the lower surface of the perovskite thin film is in contact with the electron transport layer, and the upper surface is in contact with the hole transport layer. When excess PbI2 forms on both surfaces of the perovskite thin film and decomposes into elemental iodine (I2) under illumination, the highly diffusive and strongly oxidizing I2 creates electron traps at the electron transport layer interface, reducing electron extraction efficiency. Simultaneously, I2 oxidizes the hole transport layer material, increasing interfacial resistance and thus reducing the photoelectric conversion efficiency of the perovskite solar cell. In this invention, after adjusting the relative humidity, a low-voltage DC current is applied to the substrate and the second composite mesh, causing uniform Joule heating in the in-plane direction of both composite meshes, thereby forming a localized high-temperature region at the upper and lower interfaces of the wet film. This localized high-temperature region accelerates the evaporation of the solvent at the upper and lower interfaces, not only allowing the precursor near the upper and lower interfaces of the wet film to enter a stable nucleation stage but also promoting the rapid growth of perovskite grains. This results in a denser homogeneous structure at the upper and lower interfaces of the wet film, reducing the possibility of PbI2 insertion into the perovskite grains due to lattice relaxation. By using the above-mentioned electro-induced Joule heating, the generation of PbI2 at the interface between the perovskite thin film, the electron transport layer, and the hole transport layer can be further suppressed, thereby reducing the adverse effects of I2 generated by the photodecomposition of PbI2 on the electron transport layer and the hole transport layer.

[0016] Optionally, MXene powder and anhydrous dichloromethane are mixed and stirred for 5-15 minutes. Succinyl chloride is added under nitrogen protection, heated to 30-35°C and ultrasonically reacted for 1-3 hours. After filtration, the mixture is washed 3-5 times with anhydrous dichloromethane. The resulting solid particles are then mixed evenly with anhydrous ethanol and vacuum filtered through a hydrophobic filter membrane with a pore size of 0.1-0.45 μm to form a self-supporting membrane. After drying at 40-80°C for 50-60 minutes, the self-supporting membrane is peeled off from the hydrophobic filter membrane to obtain a composite mesh.

[0017] In this invention, by controlling the heating time, temperature, and film-forming conditions of MXene powder and succinyl chloride, succinyl chloride is stably grafted onto the MXene surface, constructing a self-supporting film with sheet-like and porous characteristics, providing a carrier basis for the migration and uniform distribution of functional groups during the subsequent perovskite film annealing process.

[0018] Optionally, 1-allyl-3-methylimidazolium iodide and 2-hydroxy-2-methyl-1-phenyl-1-propanone are added to anhydrous acetonitrile, stirred at 300-600 rpm for 10-20 min, sonicated at 100-300 W for 5-10 min, and filtered to remove impurities to obtain the buffer.

[0019] In this invention, 1-allyl-3-methylimidazolium iodide and 2-hydroxy-2-methyl-1-phenyl-1-propanone are stirred, sonicated, and filtered to ensure complete dissolution and uniform dispersion in anhydrous acetonitrile, resulting in a stable buffer. This buffer improves the wetting and spreading of the precursor solution on the surface of the composite mesh, thereby enhancing the uniformity of perovskite film formation.

[0020] Optionally, lead iodide, formamidinium hydroiodide, cesium iodide, methyl ammonium chloride, methyl ammonium bromide, and 4-hydrazylbenzenesulfonic acid are mixed and stirred, urea, DMSO, and DMF are added, and the mixture is magnetically stirred at 60-70°C for 2-4 hours. After standing for 40-50 minutes to eliminate bubbles, the mixture is filtered to remove impurities, and the precursor solution is obtained.

[0021] In this invention, by allowing the solution to stand for degassing and then filtering, bubbles and impurities in the precursor solution can be effectively removed, avoiding the introduction of defects such as pores and pinholes during spin coating, which is beneficial for obtaining a more uniform and dense perovskite film.

[0022] Optionally, a first composite mesh is laid on the substrate, heated to 40-60℃ and subjected to a gas pressure of 0.2-0.4MPa for 7-10 minutes, a buffer is added, and the substrate is spin-coated at 1000-1500 rpm for 5-10 seconds. The substrate is then irradiated with ultraviolet light of 300-360 nm wavelength for 20-40 seconds, a precursor solution is added, and a wet film is formed through two-stage spin-coating. A second composite mesh is then laid, rotated at 3000-5000 rpm for 5-10 seconds, ethyl acetate is added, and the substrate is rotated for another 10-15 seconds. The substrate is then transferred to a heating stage at 80-100℃, the relative humidity is adjusted to 30%-50%, and the temperature is raised to 110-130℃ for 10-30 minutes before annealing to obtain a perovskite thin film.

[0023] In this invention, by sequentially introducing a composite mesh, buffer treatment, and controlled spin coating and annealing processes onto a substrate, the precursor solution is uniformly spread and stably formed on the surface of the composite mesh. Combined with anti-solvent-induced crystallization and controlled humidity and heat treatment conditions, it is beneficial to regulate the nucleation and grain growth process of perovskite, reduce the generation of grain boundary defects, and thus improve the film quality of perovskite thin films.

[0024] Optionally, the two-stage spin coating is as follows: first spin coating at a speed of 1000~2000 rpm for 8~12 seconds, and then spin coating at a speed of 3000~5000 rpm for 30~40 seconds.

[0025] In this invention, a two-stage spin coating method is adopted, first at low speed and then at high speed. In the low-speed stage, the precursor solution is fully wetted and evenly spread on the surface of the composite mesh. Then, in the high-speed stage, excess solution is quickly removed. This is beneficial to obtaining a uniform wet film structure and provides stable initial conditions for the subsequent crystallization process.

[0026] The present invention also provides a perovskite thin film, prepared by the above-described process and proportions. The perovskite thin film comprises a composite mesh, a buffer, a precursor solution, and ethyl acetate. The composite mesh comprises the following raw materials in parts by weight: 1-2 parts of MXene powder, 50-200 parts of anhydrous dichloromethane, 5-10 parts of succinyl chloride, and 100-500 parts of anhydrous ethanol. The buffer comprises the following raw materials in parts by weight: 5-12 parts of 1-allyl-3-methylimidazolium iodide, 0.1-0.2 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 100-180 parts of anhydrous acetonitrile.

[0027] Optionally, the precursor solution comprises the following raw materials in parts by weight: 250-270 parts lead iodide, 80-90 parts formamidinium hydroiodate, 10-12 parts cesium iodide, 6-7 parts methylammonium chloride, 1-2 parts methylammonium bromide, 0.8-1 parts 4-hydrazinobenzenesulfonic acid, 1.5-1.8 parts urea, 100-110 parts DMSO, and 400-410 parts DMF; the ethyl acetate is in parts by weight of 10-30.

[0028] The present invention also provides a perovskite solar cell, comprising a substrate, a perovskite thin film, a hole transport layer and a top electrode layer stacked sequentially, wherein the perovskite thin film is prepared using the above-described process and proportions.

[0029] The above-described technical solution of the present invention has at least the following beneficial effects:

[0030] This invention prepares a composite mesh with a sheet-like porous conductive network by reacting MXene powder and succinyl chloride, and embeds it into the bottom and top surfaces of a wet film. During annealing and crystallization, succinyl chloride migrates from the composite mesh into the interior of the wet film and enters the grain boundary regions between perovskite grains. Its carbonyl functional groups can interact with uncoordinated Pb. 2+ The reaction occurs, achieving grain boundary passivation and suppressing moisture-induced PbI2 formation, thereby reducing defect density, decreasing carrier transport loss, improving the film uniformity of perovskite films, and ultimately enhancing the open-circuit voltage and fill factor of perovskite solar cells.

[0031] Furthermore, a buffer was prepared by blending 1-allyl-3-methylimidazolium iodide with 2-hydroxy-2-methyl-1-phenyl-1-propanone. This buffer was spin-coated onto the surface of the first composite mesh and then subjected to UV irradiation, further improving the uniformity of the perovskite film formation. 2-hydroxy-2-methyl-1-phenyl-1-propanone acted as a photoinitiator, promoting the cross-linking of the buffer and stabilizing it on the composite mesh surface. 1-allyl-3-methylimidazolium iodide improved the wetting and spreading of the precursor solution on the composite mesh surface and, in the early stages of film formation, interacted with Pb... 2+ and I - The reversible mutual adsorption balances the ion distribution at the interface, slows down the abrupt change in the nucleation rate, and allows perovskite to nucleate more uniformly near the composite mesh, thereby improving the film quality. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of a perovskite solar cell in an embodiment of the present invention;

[0033] Figure 2 This is a SEM image of the perovskite thin film in Example 1 of the present invention;

[0034] Figure 3 This is a SEM image of the perovskite thin film in Comparative Example 1 of the present invention.

[0035] In the picture:

[0036] 1. Substrate; 11. Bottom electrode layer; 12. Electron transport layer; 2. Perovskite thin film; 3. Hole transport layer; 4. Top electrode layer. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0038] Preparation: Select FTO conductive glass as the bottom electrode layer, clean it with deionized water, and then dry its surface moisture; spin-coat an electron transport layer on the FTO conductive glass, and allow it to age to obtain the substrate.

[0039] Example 1

[0040] One part of MXene powder and 50 parts of anhydrous dichloromethane were mixed and mechanically stirred for 5 min. Under nitrogen protection, 5 parts of succinyl chloride were added, heated to 30℃ and ultrasonically reacted for 1 h. After filtration, the mixture was washed three times with anhydrous dichloromethane. The resulting particles were then mixed evenly with 100 parts of anhydrous ethanol and vacuum filtered through a hydrophobic filter membrane with a pore size of 0.1 μm at a pressure of -0.05 MPa for 20 min to form a self-supporting membrane. After drying at 40℃ for 50 min, the self-supporting membrane was peeled off from the hydrophobic filter membrane to obtain a composite mesh.

[0041] Five parts of 1-allyl-3-methylimidazolium iodide and 0.1 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone were added to 100 parts of anhydrous acetonitrile. The mixture was magnetically stirred at 300 rpm for 10 min, ultrasonically treated at 100 W for 5 min, and filtered to remove impurities to obtain the buffer.

[0042] 250 parts lead iodide, 80 parts formamidinium hydroiodate, 10 parts cesium iodide, 6 parts methylammonium chloride, 1 part methylammonium bromide, and 0.8 parts 4-hydrazinobenzenesulfonic acid were mixed and stirred. 1.5 parts urea, 100 parts DMSO, and 400 parts DMF were added. The mixture was magnetically stirred at 60°C for 2 hours, allowed to stand for 40 minutes to eliminate bubbles, and then filtered through a 0.22 μm pore size filter to remove impurities, thus obtaining the precursor solution.

[0043] The first composite mesh was laid flat on the substrate, heated to 40°C, and subjected to a constant pressure of 0.2 MPa for 7 minutes. Three parts of buffer solution were dropped onto the center of the first composite mesh, and spin-coated at 1000 rpm for 5 seconds. The mesh was then irradiated with 300 nm ultraviolet light for 20 seconds. Five parts of precursor solution were dropped onto the center of the first composite mesh, and spin-coated at 1000 rpm for 8 seconds, followed by spin-coating at 3000 rpm for 30 seconds to form a wet film. The second composite mesh was then laid flat on the wet... On the membrane, rotate at 3000 rpm for 5 seconds, drop 10 parts of ethyl acetate onto the second composite mesh, continue rotating for 10 seconds, transfer the substrate to a heating stage at 80°C, adjust the relative humidity of the environment to 30%, use electric clamps to establish electrical connections with the substrate and the second composite mesh respectively, apply a low-voltage DC current of 60mA and 0.5V for 5 seconds, raise the temperature of the heating stage to 110°C and heat for 10 minutes, then cool and anneal to obtain a perovskite thin film.

[0044] A hole transport layer was spin-coated onto a perovskite thin film, and a top electrode layer was deposited on the hole transport layer. The film was then aged in a dry environment for 2 hours to obtain a perovskite solar cell.

[0045] Example 2

[0046] 1.5 parts of MXene powder and 100 parts of anhydrous dichloromethane were mixed and mechanically stirred for 10 min. Under nitrogen protection, 8 parts of succinyl chloride were added, heated to 32℃ and ultrasonically reacted for 2 h. After filtration, the mixture was washed 4 times with anhydrous dichloromethane. The resulting particles were then mixed evenly with 300 parts of anhydrous ethanol and vacuum filtered through a hydrophobic filter membrane with a pore size of 0.2 μm at a pressure of -0.03 MPa for 18 min to form a self-supporting membrane. After drying at 60℃ for 55 min, the self-supporting membrane was peeled off from the hydrophobic filter membrane to obtain a composite mesh.

[0047] Eight parts of 1-allyl-3-methylimidazolium iodide and 0.15 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone were added to 150 parts of anhydrous acetonitrile. The mixture was magnetically stirred at 450 rpm for 15 min, ultrasonically treated at 200 W for 7 min, and filtered to remove impurities to obtain the buffer.

[0048] 260 parts lead iodide, 85 parts formamidinium hydroiodate, 11 parts cesium iodide, 6.5 parts methylammonium chloride, 1.5 parts methylammonium bromide, and 0.9 parts 4-hydrazinobenzenesulfonic acid were mixed and stirred. 1.7 parts urea, 105 parts DMSO, and 405 parts DMF were added. The mixture was magnetically stirred at 65°C for 3 hours, allowed to stand for 45 minutes to eliminate bubbles, and then filtered through a 0.22 μm pore size filter to remove impurities, thus obtaining the precursor solution.

[0049] The first composite mesh was laid flat on the substrate, heated to 50°C, and subjected to a constant pressure of 0.3 MPa for 8 minutes. Six parts of buffer were dropped onto the center of the first composite mesh, and spin-coated at 1200 rpm for 8 seconds. The mesh was then irradiated with 330 nm ultraviolet light for 30 seconds. Ten parts of precursor solution were dropped onto the center of the first composite mesh, and spin-coated at 1500 rpm for 10 seconds, followed by spin-coating at 4000 rpm for 35 seconds to form a wet film. The second composite mesh was then laid flat on... On the wet film, rotate at 4000 rpm for 7 seconds, drop 20 parts of ethyl acetate onto the second composite mesh, continue rotating for 12 seconds, transfer the substrate to a heating stage at 90°C, adjust the relative humidity of the environment to 40%, use electric clamps to establish electrical connections with the substrate and the second composite mesh respectively, apply a low-voltage DC current of 70mA and 0.8V for 7 seconds, raise the temperature of the heating stage to 120°C and heat for 20 minutes, then cool and anneal to obtain a perovskite thin film.

[0050] A hole transport layer was spin-coated onto a perovskite thin film, and a top electrode layer was deposited on the hole transport layer. The film was then aged in a dry environment for 3 hours to obtain a perovskite solar cell.

[0051] Example 3

[0052] Two parts of MXene powder and 200 parts of anhydrous dichloromethane were mixed and mechanically stirred for 15 min. Under nitrogen protection, 10 parts of succinyl chloride were added, heated to 35℃ and ultrasonically reacted for 3 h. After filtration, the mixture was washed five times with anhydrous dichloromethane. The resulting particles were then mixed evenly with 500 parts of anhydrous ethanol and vacuum filtered through a hydrophobic filter membrane with a pore size of 0.45 μm at a pressure of -0.02 MPa for 20 min to form a self-supporting membrane. After drying at 80℃ for 60 min, the self-supporting membrane was peeled off from the hydrophobic filter membrane to obtain a composite mesh.

[0053] 12 parts of 1-allyl-3-methylimidazolium iodide and 0.2 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone were added to 180 parts of anhydrous acetonitrile. The mixture was magnetically stirred at 600 rpm for 20 min, ultrasonically treated at 300 W for 10 min, and filtered to remove impurities to obtain the buffer.

[0054] 270 parts lead iodide, 90 parts formamidinium hydroiodate, 12 parts cesium iodide, 7 parts methylammonium chloride, 2 parts methylammonium bromide, and 1 part 4-hydrazinobenzenesulfonic acid were mixed and stirred. 1.8 parts urea, 110 parts DMSO, and 410 parts DMF were added. The mixture was magnetically stirred at 70°C for 4 hours, allowed to stand for 50 minutes to eliminate bubbles, and then filtered through a 0.22 μm pore size filter to remove impurities, thus obtaining the precursor solution.

[0055] The first composite mesh was laid flat on the substrate, heated to 60°C, and subjected to a constant pressure of 0.4 MPa for 10 minutes. Ten parts of buffer solution were dropped onto the center of the first composite mesh, and spin-coated at 1500 rpm for 10 seconds. The mesh was then irradiated with 360 nm ultraviolet light for 40 seconds. Fifteen parts of precursor solution were dropped onto the center of the first composite mesh, and spin-coated at 2000 rpm for 12 seconds, followed by spin-coating at 5000 rpm for 40 seconds to form a wet film. The second composite mesh was then laid flat. The substrate is placed on a wet film and rotated at 5000 rpm for 10 seconds. 30 parts of ethyl acetate are then dropped onto the second composite mesh. The rotation continues for 15 seconds. The substrate is then transferred to a heating stage at 100°C. The relative humidity of the environment is adjusted to 50%. Electrical connections are established between the substrate and the second composite mesh using electrical clamps. A low-voltage DC current of 80 mA and 1 V is applied for 10 seconds. The heating stage temperature is raised to 130°C and heated for 30 minutes. After cooling and annealing, a perovskite thin film is obtained.

[0056] A hole transport layer was spin-coated onto a perovskite thin film, and a top electrode layer was deposited on the hole transport layer. The film was then aged in a dry environment for 4 hours to obtain a perovskite solar cell.

[0057] Example 4

[0058] One part of MXene powder and 50 parts of anhydrous dichloromethane were mixed and mechanically stirred for 5 min. Under nitrogen protection, 5 parts of succinyl chloride were added, heated to 30℃ and ultrasonically reacted for 1 h. After filtration, the mixture was washed three times with anhydrous dichloromethane. The resulting particles were then mixed evenly with 100 parts of anhydrous ethanol and vacuum filtered through a hydrophobic filter membrane with a pore size of 0.1 μm at a pressure of -0.05 MPa for 20 min to form a self-supporting membrane. After drying at 40℃ for 50 min, the self-supporting membrane was peeled off from the hydrophobic filter membrane to obtain a composite mesh.

[0059] Five parts of 1-allyl-3-methylimidazolium iodide and 0.1 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone were added to 100 parts of anhydrous acetonitrile. The mixture was magnetically stirred at 300 rpm for 10 min, ultrasonically treated at 100 W for 5 min, and filtered to remove impurities to obtain the buffer.

[0060] 250 parts lead iodide, 80 parts formamidinium hydroiodate, 10 parts cesium iodide, 6 parts methylammonium chloride, 1 part methylammonium bromide, and 0.8 parts 4-hydrazinobenzenesulfonic acid were mixed and stirred. 1.5 parts urea, 100 parts DMSO, and 400 parts DMF were added. The mixture was magnetically stirred at 60°C for 2 hours, allowed to stand for 40 minutes to eliminate bubbles, and then filtered through a 0.22 μm pore size filter to remove impurities, thus obtaining the precursor solution.

[0061] The first composite mesh was laid flat on the substrate, heated to 40°C and subjected to constant pressure of 0.2 MPa for 7 min. Three parts of buffer were added to the center of the first composite mesh, and spin-coated at 1000 rpm for 5 s. It was then irradiated with 300 nm ultraviolet light for 20 s. Five parts of precursor solution were added to the center of the first composite mesh, and spin-coated at 1000 rpm for 8 s, then at 3000 rpm for 30 s to form a wet film. The second composite mesh was laid flat on the wet film and rotated at 3000 rpm for 5 s. Ten parts of ethyl acetate were added to the second composite mesh, and the rotation was continued for 10 s. The substrate was transferred to a heating stage at 80°C, the relative humidity was adjusted to 30%, the heating stage temperature was increased to 110°C and heated for 10 min. After cooling and annealing, a perovskite thin film was obtained.

[0062] A hole transport layer was spin-coated onto a perovskite thin film, and a top electrode layer was deposited on the hole transport layer. The film was then aged in a dry environment for 2 hours to obtain a perovskite solar cell.

[0063] Example 5

[0064] 1.5 parts of MXene powder and 100 parts of anhydrous dichloromethane were mixed and mechanically stirred for 10 min. Under nitrogen protection, 8 parts of succinyl chloride were added, heated to 32℃ and ultrasonically reacted for 2 h. After filtration, the mixture was washed 4 times with anhydrous dichloromethane. The resulting particles were then mixed evenly with 300 parts of anhydrous ethanol and vacuum filtered through a hydrophobic filter membrane with a pore size of 0.2 μm at a pressure of -0.03 MPa for 18 min to form a self-supporting membrane. After drying at 60℃ for 55 min, the self-supporting membrane was peeled off from the hydrophobic filter membrane to obtain a composite mesh.

[0065] Eight parts of 1-allyl-3-methylimidazolium iodide and 0.15 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone were added to 150 parts of anhydrous acetonitrile. The mixture was magnetically stirred at 450 rpm for 15 min, ultrasonically treated at 200 W for 7 min, and filtered to remove impurities to obtain the buffer.

[0066] 260 parts lead iodide, 85 parts formamidinium hydroiodate, 11 parts cesium iodide, 6.5 parts methylammonium chloride, 1.5 parts methylammonium bromide, and 0.9 parts 4-hydrazinobenzenesulfonic acid were mixed and stirred. 1.7 parts urea, 105 parts DMSO, and 405 parts DMF were added. The mixture was magnetically stirred at 65°C for 3 hours, allowed to stand for 45 minutes to eliminate bubbles, and then filtered through a 0.22 μm pore size filter to remove impurities, thus obtaining the precursor solution.

[0067] The first composite mesh was laid flat on the substrate, heated to 50°C and subjected to constant pressure of 0.3 MPa for 8 min. Six parts of buffer were added to the center of the first composite mesh, and spin-coated at 1200 rpm for 8 s. The mesh was then irradiated with 330 nm ultraviolet light for 30 s. Ten parts of precursor solution were added to the center of the first composite mesh, and spin-coated at 1500 rpm for 10 s, then at 4000 rpm for 35 s to form a wet film. The second composite mesh was laid flat on the wet film and rotated at 4000 rpm for 7 s. Twenty parts of ethyl acetate were added to the second composite mesh, and the mesh was rotated for another 12 s. The substrate was then transferred to a heating stage at 90°C. The relative humidity of the environment was adjusted to 40%. The temperature of the heating stage was increased to 120°C and heated for 20 min. The mesh was then cooled and annealed to obtain a perovskite thin film.

[0068] A hole transport layer was spin-coated onto a perovskite thin film, and a top electrode layer was deposited on the hole transport layer. The film was then aged in a dry environment for 3 hours to obtain a perovskite solar cell.

[0069] Example 6

[0070] Two parts of MXene powder and 200 parts of anhydrous dichloromethane were mixed and mechanically stirred for 15 min. Under nitrogen protection, 10 parts of succinyl chloride were added, heated to 35℃ and ultrasonically reacted for 3 h. After filtration, the mixture was washed five times with anhydrous dichloromethane. The resulting particles were then mixed evenly with 500 parts of anhydrous ethanol and vacuum filtered through a hydrophobic filter membrane with a pore size of 0.45 μm at a pressure of -0.02 MPa for 20 min to form a self-supporting membrane. After drying at 80℃ for 60 min, the self-supporting membrane was peeled off from the hydrophobic filter membrane to obtain a composite mesh.

[0071] 12 parts of 1-allyl-3-methylimidazolium iodide and 0.2 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone were added to 180 parts of anhydrous acetonitrile. The mixture was magnetically stirred at 600 rpm for 20 min, ultrasonically treated at 300 W for 10 min, and filtered to remove impurities to obtain the buffer.

[0072] 270 parts lead iodide, 90 parts formamidinium hydroiodate, 12 parts cesium iodide, 7 parts methylammonium chloride, 2 parts methylammonium bromide, and 1 part 4-hydrazinobenzenesulfonic acid were mixed and stirred. 1.8 parts urea, 110 parts DMSO, and 410 parts DMF were added. The mixture was magnetically stirred at 70°C for 4 hours, allowed to stand for 50 minutes to eliminate bubbles, and then filtered through a 0.22 μm pore size filter to remove impurities, thus obtaining the precursor solution.

[0073] The first composite mesh was laid flat on the substrate, heated to 60°C and subjected to constant pressure of 0.4 MPa for 10 min. Ten parts of buffer were added to the center of the first composite mesh, and spin-coated at 1500 rpm for 10 s. It was then irradiated with ultraviolet light at a wavelength of 360 nm for 40 s. Fifteen parts of precursor solution were added to the center of the first composite mesh, and spin-coated at 2000 rpm for 12 s, then at 5000 rpm for 40 s to form a wet film. The second composite mesh was laid flat on the wet film and rotated at 5000 rpm for 10 s. Thirty parts of ethyl acetate were added to the second composite mesh, and the rotation was continued for 15 s. The substrate was transferred to a heating stage at 100°C, the relative humidity was adjusted to 50%, the heating stage temperature was increased to 130°C and heated for 30 min. After cooling and annealing, the perovskite film was obtained.

[0074] A hole transport layer was spin-coated onto a perovskite thin film, and a top electrode layer was deposited on the hole transport layer. The film was then aged in a dry environment for 4 hours to obtain a perovskite solar cell.

[0075] The present invention also includes comparative examples and related experiments.

[0076] Comparative Example 1

[0077] The only difference from Example 1 is that succinyl chloride was not added; all other components and preparation steps were exactly the same, resulting in a perovskite thin film and a perovskite solar cell.

[0078] Comparative Example 2

[0079] The only difference from Example 1 is that 1-allyl-3-methylimidazolium iodide was not added; all other components and preparation steps were exactly the same, resulting in perovskite thin films and perovskite solar cells.

[0080] Comparative Example 3

[0081] The only difference from Example 1 is that ultraviolet light irradiation was not used; all other components and preparation steps were exactly the same, resulting in perovskite thin films and perovskite solar cells.

[0082] Comparative Example 4

[0083] The only difference from Example 1 is that no composite mesh was used; all other components and preparation steps were exactly the same, resulting in a perovskite thin film and a perovskite solar cell.

[0084] Performance testing

[0085] Microstructure testing: Field emission scanning electron microscopy was used to test the perovskite films prepared in Example 1 and Comparative Example 1, respectively. The test results are as follows: Figure 2 and Figure 3 As shown.

[0086] Electrochemical performance testing: Tests were conducted according to standard DB35T 2143-2023 "Test Procedure for Conversion Efficiency of Perovskite Solar Cells". The open-circuit voltage V of the perovskite solar cells prepared in Examples 1-6 and Comparative Examples 1-4 was measured. oc Fill factor FF, short-circuit current density J sc The photoelectric conversion efficiency (PCE) was tested, and the test results are shown in Table 1.

[0087] Table 1

[0088]

[0089] like Figure 1 As shown, the perovskite solar cells prepared in Examples 1 to 6 include a substrate 1, a perovskite thin film 2, a hole transport layer 3, and a top electrode layer 4 stacked sequentially from bottom to top. The substrate 1 includes a bottom electrode layer 11 and an electron transport layer 12 stacked sequentially from bottom to top.

[0090] As shown in Table 1, compared with Examples 4-6, the open-circuit voltage and fill factor of the perovskite solar cells in Examples 1-3 are improved. This indicates that applying a low-voltage DC current between the substrate and the second composite mesh during the perovskite thin film preparation process helps to improve the open-circuit voltage and fill factor of the perovskite solar cells, thereby improving the photoelectric conversion efficiency of the perovskite solar cells.

[0091] Combining Table 1 and Figure 2 and Figure 3 The test results show that, compared with Example 1, the perovskite film uniformity of Comparative Example 1 decreased due to the absence of succinyl chloride, resulting in a significant decrease in the fill factor of the open-circuit voltage of the final perovskite solar cell. This indicates that succinyl chloride helps improve the fill factor of perovskite solar cells, thereby increasing photoelectric conversion efficiency. Compared with Example 1, the perovskite film prepared in Comparative Example 2 lacked 1-allyl-3-methylimidazolium iodide, and the open-circuit voltage of the perovskite solar cell prepared from it decreased significantly. This indicates that the introduction of 1-allyl-3-methylimidazolium iodide helps improve the perovskite film uniformity of the final perovskite solar cell. The open-circuit voltage of the perovskite solar cell is reduced, thereby improving the photoelectric conversion efficiency. Compared with Example 1, the perovskite film prepared in Comparative Example 3 was not treated with ultraviolet light, and the open-circuit voltage and fill factor of the perovskite solar cell prepared from it were lower than those of Example 1, indicating that ultraviolet light treatment helps to improve the photoelectric conversion efficiency of the perovskite solar cell. Compared with Example 1, the perovskite film prepared in Comparative Example 4 lacked a composite mesh, and the open-circuit voltage and fill factor of the perovskite solar cell prepared from it decreased, indicating that the use of a composite mesh helps to improve the photoelectric conversion efficiency of the perovskite solar cell.

[0092] The above are preferred embodiments of the present invention. Those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A process for preparing a perovskite thin film, characterized by, The preparation steps include: S1. MXene powder and anhydrous dichloromethane are mixed and stirred, succinyl chloride is added under nitrogen protection, heated, ultrasonically treated, filtered, washed with anhydrous dichloromethane, the obtained particles are mixed with anhydrous ethanol, vacuum filtration is performed, and the obtained self-supporting membrane is heated and dried to obtain a composite mesh; S2. 1-allyl-3-methylimidazole iodide and 2-hydroxy-2-methyl-1-phenyl-1-propanone are added to anhydrous acetonitrile, stirred at a speed of 300-600 rpm for 10-20 min, ultrasonically treated at a power of 100-300 W for 5-10 min, and filtered to remove impurities to obtain a buffer; S3. Lead iodide, formamidine hydroiodide, cesium iodide, methylammonium chloride, methylammonium bromide, and 4-hydrazinylbenzenesulfonic acid are mixed, urea, DMSO and DMF are added, heated and stirred, and filtered after standing to obtain a precursor solution; S4. A first piece of the composite mesh is laid on the substrate, heated and pressurized, the buffer is added dropwise, spin-coated, irradiated with ultraviolet light, the precursor solution is added dropwise, a second piece of the composite mesh is laid after the wet film is formed by two-stage spin coating, ethyl acetate is added dropwise, spin-coated, the relative humidity is adjusted, and annealed to obtain a perovskite film.

2. The process for preparing a perovskite thin film according to claim 1, wherein After adjusting the relative humidity, low-voltage direct current is also applied between the substrate and the second piece of the composite mesh, and the specific steps are as follows: an electric clamp is used to establish electrical connection with the substrate and the second piece of the composite mesh, respectively, and low-voltage direct current is applied for 5-10 s; the current of the low-voltage direct current is 60-80 mA, and the voltage is 0.5-1 V; the substrate includes a bottom electrode layer and an electron transport layer stacked in sequence.

3. The process for preparing a perovskite thin film according to claim 1, wherein MXene powder and anhydrous dichloromethane are mixed and stirred for 5-15 min, succinyl chloride is added under nitrogen protection, heated to 30-35℃ and ultrasonically reacted for 1-3 h, filtered, washed with anhydrous dichloromethane for 3-5 times, the obtained solid particles are uniformly mixed with anhydrous ethanol, vacuum filtration is performed using a hydrophobic filter membrane with a pore size of 0.1-0.45 μm to form a self-supporting membrane, the self-supporting membrane is peeled off from the hydrophobic filter membrane after being heated to 40-80℃ and dried for 50-60 min, and the composite mesh is obtained. 4.The process of claim 1, wherein 1-allyl-3-methylimidazole iodide and 2-hydroxy-2-methyl-1-phenyl-1-propanone are added to anhydrous acetonitrile, stirred at a speed of 300-600 rpm for 10-20 min, ultrasonically treated at a power of 100-300 W for 5-10 min, and filtered to remove impurities to obtain a buffer.

5. The preparation process of a perovskite thin film according to claim 1, characterized in that, Lead iodide, formamidine hydroiodide, cesium iodide, methylammonium chloride, methylammonium bromide, and 4-hydrazinylbenzenesulfonic acid are mixed and stirred, urea, DMSO and DMF are added, magnetically stirred at 60-70℃ for 2-4 h, and filtered after standing for 40-50 min to remove bubbles to obtain a precursor solution.

6. The preparation process of a perovskite thin film according to claim 1, characterized in that, A first piece of composite mesh is laid on a substrate, heated to 40-60 DEG C and treated under 0.2-0.4 MPa air pressure for 7-10 min, a buffer is added dropwise, spin-coated at 1000-1500 rpm for 5-10 s, irradiated with UV light of 300-360 nm wavelength for 20-40 s, a precursor solution is added dropwise, a wet film is formed by two-stage spin coating, a second piece of composite mesh is laid, rotated at 3000-5000 rpm for 5-10 s, ethyl acetate is added dropwise, and the rotation is continued for 10-15 s, the substrate is transferred to a heating platform with a temperature of 80-100 DEG C, the relative humidity of the environment is adjusted to 30-50%, and annealing is performed by heating to 110-130 DEG C for 10-30 min to obtain a perovskite film.

7. The process of claim 6, wherein the perovskite film is prepared by a method comprising the steps of: The two-stage spin coating is spin coating at 1000-2000 rpm for 8-12 s, and then spin coating at 3000-5000 rpm for 30-40 s.

8. A perovskite thin film, characterized by, The perovskite film is prepared by the preparation process of any one of claims 1-7, and comprises a composite mesh, a buffer, a precursor solution and ethyl acetate, the composite mesh comprises the following raw materials in parts by weight: MXene powder 1-2 parts, anhydrous dichloromethane 50-200 parts, succinyl chloride 5-10 parts, and anhydrous ethanol 100-500 parts; the buffer comprises the following raw materials in parts by weight: 1-allyl-3-methylimidazolium iodide 5-12 parts, 2-hydroxy-2-methyl-1-phenyl-1-propanone 0.1-0.2 parts, and anhydrous acetonitrile 100-180 parts.

9. The perovskite thin film according to claim 8, wherein The precursor solution comprises the following raw materials in parts by weight: lead iodide 250-270 parts, formamidinium hydroiodide 80-90 parts, cesium iodide 10-12 parts, methylammonium chloride 6-7 parts, methylammonium bromide 1-2 parts, 4-hydrazinobenzenesulfonic acid 0.8-1 part, urea 1.5-1.8 parts, DMSO 100-110 parts, and DMF 400-410 parts; and the ethyl acetate is 10-30 parts by weight.

10. A perovskite solar cell, characterized by, A perovskite film is prepared by the preparation process of any one of claims 1-7.

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