A method for improving the crystallinity of vacuum-deposited perovskite thin films and its application

Abstract

This invention discloses a method for improving the crystallinity of vacuum-deposited perovskite thin films and its application, comprising the following steps: S1: preliminary preparation of perovskite thin films; S2: screening of perovskite thin films; S3: dissolving halides in solvent A to prepare a reaction solution; S4: placing the perovskite thin film on a substrate stage in a sealed vacuum chamber; S5: using an ultrasonic atomizing device to convert the reaction solution into an atomized reaction solution, which is then carried into the vacuum chamber by a carrier gas, and finally annealed to obtain a highly crystalline, uniform, and dense perovskite thin film. This invention improves the crystallinity quality and uniformity of the perovskite thin film by optimizing the composition and concentration of the reaction solution, the ultrasonic atomizing frequency and temperature, the atomizing gas flow rate and velocity, the chamber vacuum degree, and the substrate stage temperature. The obtained perovskite thin film, when applied to perovskite solar cells, exhibits high photoelectric conversion efficiency and stability, which can promote the large-area practical application of perovskite solar cells.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a method for improving the crystallinity of vacuum-deposited perovskite thin films and its application. Background Technology

[0002] Perovskite solar cells have garnered global attention due to their significant advantages such as low cost and high efficiency. Since their introduction, in just ten years, their photoelectric conversion efficiency has reached 26.25%, comparable to crystalline silicon solar cells, making them an important research direction in my country's new energy field. Nevertheless, large-scale mass production of PSCs still faces many challenges, particularly the issue of uniformity in large-area fabrication processes. High-efficiency perovskite cells require perovskite thin films with high crystallinity and dense film coverage.

[0003] Currently, the main methods for preparing perovskite thin films are solution coating and vacuum coating. While the mainstream method for large-area thin film preparation is solution coating, which is simple to operate and has low initial equipment investment costs, it suffers from significant susceptibility to environmental temperature, humidity, and atmosphere, resulting in poor repeatability and low yield. Compared to solution coating, vacuum coating is more precise, allowing for thin film preparation in a higher vacuum environment, reducing the interference of the external environment on film quality, and improving production stability and controllability. However, vacuum coating also faces some challenges. Metal halide thin films prepared by vacuum evaporation are typically stacked layer by layer in the form of nanosheets. However, in thicker films, these layered structures may be too dense, making the film layer insufficiently porous. This dense structure hinders the penetration of organic salts in the second step, preventing the metal halide generated in the first step from fully reacting with the organic halide in the second step. This problem easily leads to metal halide residues in the film, affecting the film quality and ultimately the performance of the device, severely hindering the commercialization of perovskite solar cells.

[0004] Therefore, a method is needed to improve the crystallinity of vacuum-deposited perovskite films to solve the technical problem of poor perovskite film crystal quality caused by the difficulty in penetrating organic halides in the second step of vacuum-deposited perovskite films. Summary of the Invention

[0005] This invention discloses a method for improving the crystallinity of vacuum-deposited perovskite thin films and its application, aiming to solve the technical problems in the background art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for improving the crystallinity of vacuum-deposited perovskite thin films includes the following specific steps:

[0008] S1: Preliminary preparation of perovskite thin films:

[0009] S1.1: Substrate preparation: Before vacuum deposition, the surface of the thin film substrate is cleaned to remove organic impurities and contaminants. Then, the thin film substrate is thermally annealed to relieve stress. Finally, a relatively pure oxide substrate is formed on the surface of the thin film substrate.

[0010] Cleaning can improve crystallinity, and thermal annealing can improve the crystallinity of perovskite films. Forming a relatively pure oxide layer on the substrate surface can promote film crystal growth.

[0011] S1.2: Vacuum system preparation: Clean the inside of the vacuum chamber to ensure it is free of dust and impurities, install a suitable reaction chamber and heating source, ensure the atmosphere in the reaction chamber is dry and oxygen-free, and reduce the gas pressure to the required range by vacuum pumping.

[0012] S1.3: Vacuum deposition: The thin film substrate is placed in the reaction chamber for vacuum deposition. During the vacuum deposition process, appropriate deposition parameters are controlled. Reasonable deposition parameters can promote crystal growth and improve crystallinity.

[0013] S1.4: Post-processing: After deposition, thermal annealing is used to further improve the order and crystallinity of the perovskite thin film crystals. Then, light or laser annealing is used to reasonably control the impurity content during the deposition process and further optimize crystallinity and impurity removal. The presence of impurities may lead to crystal defects, the formation of amorphous structures and other problems, so effective impurity removal is required.

[0014] S1.5: Result Characterization: The crystallinity of the perovskite film was characterized and analyzed using X-ray diffraction (XRD) or scanning electron microscopy (SEM).

[0015] By optimizing various aspects of the initial perovskite film preparation process, such as preheating, using a pure oxide substrate, and performing heat annealing, light irradiation, or laser annealing after deposition, the crystallinity of the perovskite film can be further improved, reducing the number of incompletely crystallized perovskite films. This reduces the probability of subsequent secondary processing and also improves the crystallinity of incompletely crystallized perovskite films, making subsequent secondary processing easier.

[0016] S2: Screening of perovskite films: Based on the crystallinity analysis results of S1.5, perovskite films with incomplete crystallization are screened from the perovskite films prepared in S1.

[0017] S3: Dissolve the halide in solvent A to prepare a reaction solution with a total solute concentration of 0-5 mol / L;

[0018] S4: Place the incompletely crystallized perovskite films selected in S2 onto a substrate stage in a sealed vacuum chamber. The vacuum level of the chamber is controlled to be 5*10⁻⁶ using a vacuum pump. -4 -5*10 4 Pa;

[0019] S5: The reaction liquid in S3 is converted into an atomized reaction liquid using an ultrasonic atomizing device. The atomized reaction liquid is then carried into the vacuum chamber in S4 by a carrier gas. The vacuum environment allows the atomized reaction liquid to be rapidly and evenly distributed and act on the surface and interior of the vacuum-deposited perovskite film that is not fully crystallized. After annealing, it can be recrystallized and then grown again to obtain a highly crystalline, uniform and dense perovskite film.

[0020] Incompletely crystallized perovskite films are placed on a substrate stage in a vacuum chamber with a certain degree of vacuum. The reaction solution is atomized by ultrasonic atomization and introduced into the vacuum chamber along with the carrier gas. The vacuum environment allows the atomized reaction to spread rapidly and uniformly on the surface and interior of the incompletely crystallized perovskite film. The substrate stage is then heated. Because recrystallization and secondary growth are carried out in a vacuum environment with a pure atmosphere and few impurities, the prepared film exhibits excellent performance in terms of uniformity, density, and defect severity.

[0021] In a preferred embodiment, in step S1.1, the thin film substrate can be cleaned using a cleaning agent, solvent, or ultrasonic cleaning method. The oxide substrate uses zirconium oxide or aluminum oxide as the main substrate and also includes nickel oxide, tin oxide, organic monolayer, and polymer.

[0022] In a preferred embodiment, in S1.3, the deposition parameters include deposition temperature, deposition rate, gas flow rate, and atmosphere composition.

[0023] In a preferred embodiment, the initial preparation of the perovskite thin film in S1 can also be achieved by co-evaporation, multi-step continuous evaporation, vacuum-solution two-step method, or solution coating method.

[0024] In a preferred embodiment, in S3, the halide is one or a mixture of two or more of the following: methyl iodine, methyl chloromethamine, methyl bromide, formamidine iodomethacin, cesium chloride, cesium iodide, cesium bromide, and rubidium chloride.

[0025] In a preferred embodiment, in S3, solvent A is one or a mixture of two or more of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, γ-butyrolactone, N,N-dimethylpropenylurea, N,N-dimethylacetamide, isopropanol, and water.

[0026] In a preferred embodiment, the carrier gas in step S5 can be nitrogen, argon, or dry air.

[0027] In a preferred embodiment, during step S5, the substrate stage temperature is controlled at 25-300℃, the atomizing gas flow rate is 0.1-30mL / min, and the reaction time is 0.1-120min.

[0028] In a preferred embodiment, the perovskite thin film can be used as a light-absorbing layer in a solar cell module.

[0029] As can be seen from the above, the preparation method for improving the crystallinity of vacuum-deposited perovskite thin films provided by the present invention improves the crystallinity quality and uniformity of perovskite thin films by optimizing the composition and concentration of the reaction solution, the frequency and temperature of ultrasonic atomization, the flow rate and rate of atomizing gas, the vacuum degree of the cavity and the temperature of the substrate stage. Moreover, the preparation method is simple, has high uniformity and stability, is compatible with various vacuum deposition methods, is easy to scale up the substrate size, and has great potential for improvement. At the same time, this preparation method can be used on small-area and industrial-scale large-area perovskite solar cells, flexible cells, rigid cells, crystalline silicon tandem cells and other unconventional substrates, and can achieve large-area homogeneous and conformal deposition of thin films, which has great potential.

[0030] This preparation method can obtain large-area, uniform, and dense perovskite thin films. When applied to perovskite solar cells, it achieves high photoelectric conversion efficiency and stability, which can promote the large-area practical application of perovskite solar cells and accelerate the industrialization process of perovskite-based solar cell modules. It has significant practical and economic value. Attached Figure Description

[0031] Figure 1 This is a SEM image of the perovskite film surface in Example 3 of the preparation method for improving the crystallinity of vacuum-deposited perovskite films proposed in this invention.

[0032] Figure 2 The image shows the XRD pattern of the perovskite film in Example 3 of the preparation method for improving the crystallinity of vacuum-deposited perovskite films proposed in this invention.

[0033] Figure 3 The perovskite thin film prepared by the method for improving the crystallinity of vacuum-deposited perovskite thin films proposed in this invention is shown in the current density and voltage characteristic curves of the perovskite solar cell in Application Example 4.

[0034] Figure 4 The statistical results of the long-term stability of the perovskite solar cell in Application Example 4 are presented in the preparation method for improving the crystallinity of vacuum-deposited perovskite thin films proposed in this invention.

[0035] Figure 5 This is a flowchart from Example 1 of a method for improving the crystallinity of vacuum-deposited perovskite thin films proposed in this invention.

[0036] Figure 6 This is a flowchart from Example 2 of a method for improving the crystallinity of vacuum-deposited perovskite thin films proposed in this invention. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0038] Example 1

[0039] Reference Figure 5 A method for improving the crystallinity of vacuum-deposited perovskite thin films includes the following specific steps:

[0040] S1: Preliminary preparation of perovskite thin films:

[0041] S1.1: Substrate preparation: Before vacuum deposition, the surface of the thin film substrate is cleaned to remove organic impurities and contaminants. Then, the thin film substrate is thermally annealed to relieve stress. Finally, a relatively pure oxide substrate is formed on the surface of the thin film substrate.

[0042] Cleaning can improve crystallinity, and thermal annealing can improve the crystallinity of perovskite films. Forming a relatively pure oxide layer on the substrate surface can promote film crystal growth.

[0043] S1.2: Vacuum system preparation: Clean the inside of the vacuum chamber to ensure it is free of dust and impurities, install a suitable reaction chamber and heating source, ensure the atmosphere in the reaction chamber is dry and oxygen-free, and reduce the gas pressure to the required range by vacuum pumping.

[0044] S1.3: Vacuum deposition: The thin film substrate is placed in the reaction chamber for vacuum deposition. During the vacuum deposition process, appropriate deposition parameters are controlled. Reasonable deposition parameters can promote crystal growth and improve crystallinity.

[0045] S1.4: Post-processing: After deposition, thermal annealing is used to further improve the order and crystallinity of the perovskite thin film crystals. Then, light or laser annealing is used to reasonably control the impurity content during the deposition process and further optimize crystallinity and impurity removal. The presence of impurities may lead to crystal defects, the formation of amorphous structures and other problems, so effective impurity removal is required.

[0046] S1.5: Result Characterization: The crystallinity of the perovskite film was characterized and analyzed using X-ray diffraction (XRD) or scanning electron microscopy (SEM).

[0047] By optimizing various aspects of the initial perovskite film preparation process, such as preheating, using a pure oxide substrate, and performing heat annealing, light irradiation, or laser annealing after deposition, the crystallinity of the perovskite film can be further improved, reducing the number of incompletely crystallized perovskite films. This reduces the probability of subsequent secondary processing and also improves the crystallinity of incompletely crystallized perovskite films, making subsequent secondary processing easier.

[0048] S2: Screening of perovskite films: Based on the crystallinity analysis results of S1.5, perovskite films with incomplete crystallization are screened from the perovskite films prepared in S1.

[0049] S3: Dissolve the halide in solvent A to prepare a reaction solution with a total solute concentration of 0-5 mol / L;

[0050] S4: Place the incompletely crystallized perovskite films selected in S2 onto a substrate stage in a sealed vacuum chamber. The vacuum level of the chamber is controlled to be 5*10⁻⁶ using a vacuum pump. -4 -5*10 4 Pa;

[0051] S5: The reaction liquid in S3 is converted into an atomized reaction liquid using an ultrasonic atomizing device. The atomized reaction liquid is then carried into the vacuum chamber in S4 by a carrier gas. The vacuum environment allows the atomized reaction liquid to be rapidly and evenly distributed and act on the surface and interior of the vacuum-deposited perovskite film that is not fully crystallized. After annealing, it can be recrystallized and then grown again to obtain a highly crystalline, uniform and dense perovskite film.

[0052] Incompletely crystallized perovskite films are placed on a substrate stage in a vacuum chamber with a certain degree of vacuum. The reaction solution is atomized by ultrasonic atomization and introduced into the vacuum chamber along with the carrier gas. The vacuum environment allows the atomization reaction to spread rapidly and uniformly on the surface and interior of the incompletely crystallized perovskite film. The substrate stage is then heated. Because recrystallization and secondary growth are carried out in a vacuum environment with a pure atmosphere and few impurities, the prepared film exhibits excellent performance in terms of uniformity, density, and defect level.

[0053] The perovskite film composition is an organic-inorganic lead halide perovskite. The composition of the perovskite film is controlled by the solution composition, which includes organic and inorganic components. The organic components include, but are not limited to, formamidine iodoformin and methylamine iodoformin, while the inorganic components include, but are not limited to, lead, halogens (chlorine, bromine, iodine) and cesium ions.

[0054] In a preferred embodiment, in S1.1, the thin film substrate can be cleaned using a cleaning agent, solvent, or ultrasonic cleaning method. The oxide substrate uses zirconium oxide or aluminum oxide as the main substrate and also includes nickel oxide, tin oxide, organic monolayer, and polymer.

[0055] In a preferred embodiment, in S1.3, the deposition parameters include deposition temperature, deposition rate, gas flow rate, and atmosphere composition.

[0056] In a preferred embodiment, in S1, the initial preparation of the perovskite thin film can also be carried out by co-evaporation, multi-step continuous evaporation, vacuum-solution two-step method, or solution coating method.

[0057] In a preferred embodiment, in S3, the halide is one or a mixture of two or more of the following: methyl iodine, methyl chloromethamine, methyl bromide, formamidine iodide, cesium chloride, cesium iodide, cesium bromide, and rubidium chloride.

[0058] In a preferred embodiment, in S3, solvent A is one or a mixture of two or more of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, γ-butyrolactone, N,N-dimethylpropenylurea, N,N-dimethylacetamide, isopropanol, and water.

[0059] In a preferred embodiment, in S5, the carrier gas can be nitrogen, argon, or dry air.

[0060] In a preferred embodiment, during step S5, the substrate stage temperature is controlled at 25-300°C, the atomizing gas flow rate is 0.1-30 mL / min, and the reaction time is 0.1-120 min.

[0061] In a preferred embodiment, the perovskite thin film can be applied as a light-absorbing layer in a solar cell module.

[0062] Example 2

[0063] Reference Figure 6 A method for improving the crystallinity of vacuum-deposited perovskite thin films includes the following specific steps:

[0064] S1: Preliminary preparation of perovskite thin films:

[0065] S1.1: Substrate preparation: Before vacuum deposition, the surface of the thin film substrate is cleaned to remove organic impurities and contaminants. Then, the thin film substrate is thermally annealed to relieve stress. Finally, a relatively pure oxide substrate is formed on the surface of the thin film substrate.

[0066] Cleaning can improve crystallinity, and thermal annealing can improve the crystallinity of perovskite films. Forming a relatively pure oxide layer on the substrate surface can promote film crystal growth.

[0067] S1.2: Vacuum system preparation: Clean the inside of the vacuum chamber to ensure it is free of dust and impurities, install a suitable reaction chamber and heating source, ensure the atmosphere in the reaction chamber is dry and oxygen-free, and reduce the gas pressure to the required range by vacuum pumping.

[0068] S1.3: Vacuum deposition: The thin film substrate is placed in the reaction chamber for vacuum deposition. During the vacuum deposition process, appropriate deposition parameters are controlled. Reasonable deposition parameters can promote crystal growth and improve crystallinity.

[0069] S2: Dissolve the halide in solvent A to prepare a reaction solution with a total solute concentration of 0-5 mol / L;

[0070] S3: The incompletely crystallized perovskite film prepared in S1 is placed on a substrate stage in a sealed vacuum chamber. The vacuum level of the vacuum chamber is controlled to be 5*10⁻⁶ using a vacuum pump. -4 -5*10 4 Pa;

[0071] S4: The reaction liquid in S2 is converted into an atomized reaction liquid using an ultrasonic atomizing device. The atomized reaction liquid is then carried into the vacuum chamber in S3 by a carrier gas. The vacuum environment allows the atomized reaction liquid to be rapidly and evenly distributed and act on the surface and interior of the vacuum-deposited perovskite film that is not fully crystallized. After annealing, it can be recrystallized and then grown again to obtain a highly crystalline, uniform and dense perovskite film.

[0072] Incompletely crystallized perovskite films are placed on a substrate stage in a vacuum chamber with a certain degree of vacuum. The reaction solution is atomized by ultrasonic atomization and introduced into the vacuum chamber along with the carrier gas. The vacuum environment allows the atomization reaction to spread rapidly and uniformly on the surface and interior of the incompletely crystallized perovskite film. The substrate stage is then heated. Because recrystallization and secondary growth are carried out in a vacuum environment with a pure atmosphere and few impurities, the prepared film exhibits excellent performance in terms of uniformity, density, and defect level.

[0073] The perovskite film composition is an organic-inorganic lead halide perovskite. The composition of the perovskite film is controlled by the solution composition, which includes organic and inorganic components. The organic components include, but are not limited to, formamidine iodoformin and methylamine iodoformin, while the inorganic components include, but are not limited to, lead, halogens (chlorine, bromine, iodine) and cesium ions.

[0074] In a preferred embodiment, in S1.1, the thin film substrate can be cleaned using a cleaning agent, solvent, or ultrasonic cleaning method. The oxide substrate uses zirconium oxide or aluminum oxide as the main substrate and also includes nickel oxide, tin oxide, organic monolayer, and polymer.

[0075] In a preferred embodiment, in S1.3, the deposition parameters include deposition temperature, deposition rate, gas flow rate, and atmosphere composition.

[0076] In a preferred embodiment, in S1, the initial preparation of the perovskite thin film can also be carried out by co-evaporation, multi-step continuous evaporation, vacuum-solution two-step method, or solution coating method.

[0077] In a preferred embodiment, in S3, the halide is one or a mixture of two or more of the following: methyl iodine, methyl chloromethamine, methyl bromide, formamidine iodide, cesium chloride, cesium iodide, cesium bromide, and rubidium chloride.

[0078] In a preferred embodiment, in S3, solvent A is one or a mixture of two or more of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, γ-butyrolactone, N,N-dimethylpropenylurea, N,N-dimethylacetamide, isopropanol, and water.

[0079] In a preferred embodiment, in S5, the carrier gas can be nitrogen, argon, or dry air.

[0080] In a preferred embodiment, during step S5, the substrate stage temperature is controlled at 25-300°C, the atomizing gas flow rate is 0.1-30 mL / min, and the reaction time is 0.1-120 min.

[0081] In a preferred embodiment, the perovskite thin film can be applied as a light-absorbing layer in a solar cell module.

[0082] Example 3

[0083] Preparation of highly crystalline perovskite thin films by atomization of reaction solution:

[0084] S1.1: Deposit an inorganic component thin film on the surface of a transparent conductive glass substrate (FTO / glass) using a vacuum method;

[0085] S1.2: An organic component film is deposited on the surface of the inorganic component film prepared in S1.1 using a vacuum method to obtain an incompletely crystallized perovskite film;

[0086] S2: Dissolve NH3CH3Cl in DMF to a concentration of 0.1 mol / L to obtain a reaction solution;

[0087] S3: The incompletely crystallized perovskite film prepared in S1.2 is placed on a substrate stage in a sealed vacuum chamber. The vacuum level of the vacuum chamber is controlled to be 5*10 using a vacuum pump. 3 Pa;

[0088] S4: The reaction liquid in S2 is converted into an atomized reaction liquid using an ultrasonic atomizing device. Nitrogen gas is used to carry the atomized reaction liquid into the vacuum chamber in S3. The substrate stage temperature is controlled at 120℃, the atomizing gas flow rate is 0.8mL / min, and the reaction time is 2min, to achieve a highly crystalline, uniform and dense perovskite film.

[0089] The surface microstructure of the prepared perovskite thin film was observed using a field emission scanning electron microscope (JSM-7610F Plus, Hitachi, Japan). The results are shown in [Figure number missing]. Figure 1 The crystallinity of the thin film was detected using an X-ray diffractometer (D8 Advance, Bruker, Germany). The results are shown in [Figure number missing]. Figure 2 .

[0090] Example 4

[0091] Fabrication of perovskite solar cells using atomized reaction solution:

[0092] Sa: Cleaning of solar cell substrate: The FTO substrate is patterned by laser etching. After etching, it is cleaned in sequence with detergent, deionized water, ethanol and isopropanol, and then dried for later use.

[0093] Sb: Electron transport layer preparation: A 0.1M tin oxide gel aqueous solution was prepared on an FTO substrate by blade coating or spin coating, and annealed at 200℃ for 30 min to obtain FTO glass with deposited electron transport layer;

[0094] Sc: Perovskite thin film preparation: The preparation method is basically the same as in Example 1, except that the substrate in S1.1 is FTO glass with an electron transport layer deposited on it;

[0095] Sd: Hole transport layer preparation: 72.3 mg of Spiro-OMeTAD, 28 μl of lithium bis(trifluoromethanesulfonylimide) acetonitrile solution (400 mg / ml) and 17 μl of TBP were added to 1 ml of chlorobenzene and stirred overnight to obtain a hole transport layer precursor solution. The prepared Spiro-OMeTAD solution was coated onto the perovskite layer by a doctor blade coating or spin coating method to obtain the hole transport layer.

[0096] Se: Metal counter electrode preparation: The multilayer thin film prepared in the above steps is placed into a mask and then placed in a vacuum evaporation chamber. The deposition is carried out under a vacuum level below 5*10⁻⁶. -4 After Pa, with The rate at which the silver electrode is evaporated to a thickness of The device fabrication was completed, and a perovskite solar cell was obtained by vacuum ultrasonic atomization deposition.

[0097] The fabricated perovskite solar cells achieved AM1.5 and 100 mW / cm² performance. 2The photoelectric performance of the battery was tested using a Keithley 2400 under illumination, and the statistical results are shown in Table 1 and 2. Figure 3 .

[0098] Table 1

[0099] <![CDATA[V OC (V)]]> <![CDATA[J SC (mAcm -2 )]]> FF (%) PCE (%) Example 2 1.17 26.24 82.95 25.47

[0100] After testing, the battery underwent long-term stability testing. The results of the change in photoelectric conversion efficiency are shown in Table 2 and... Figure 4 .

[0101] Table 2

[0102] Placement time 0 weeks 2 weeks 4 weeks 6 weeks Example 2 25.47％ 24.90％ 24.22％ 23.65％

[0103] The fabricated perovskite solar cells can be used as generator components and in tandem solar cell components.

[0104] The method for improving the crystallinity of vacuum-deposited perovskite thin films provided by this invention improves the crystallinity quality and uniformity of perovskite thin films by optimizing the composition and concentration of the reaction solution, the frequency and temperature of ultrasonic atomization, the flow rate and rate of atomizing gas, the vacuum degree of the cavity, and the temperature of the substrate stage. The preparation method is simple, has high uniformity and stability, is compatible with various vacuum deposition methods, is easy to scale up the substrate size, and has great potential for improvement. At the same time, this preparation method can be used on unconventional substrates such as small-area and industrial-scale large-area perovskite solar cells, flexible cells, rigid cells, and crystalline silicon tandem cells, and can achieve large-area homogeneous and conformal deposition of thin films, which has great potential.

[0105] This preparation method can obtain large-area, uniform, and dense perovskite thin films. When applied to perovskite solar cells, it achieves high photoelectric conversion efficiency and stability, which can promote the large-area practical application of perovskite solar cells and accelerate the industrialization process of perovskite-based solar cell modules. It has significant practical and economic value.

[0106] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. The substitutions may be replacements of some structures, devices, or method steps, or they may be complete technical solutions. Equivalent substitutions or modifications made to the technical solutions and inventive concepts of the present invention should all be covered within the scope of protection of the present invention.

Claims

1. A method for improving the crystallinity of vacuum-deposited perovskite thin films, characterized in that, The specific steps include the following: S1: Preliminary preparation of perovskite thin films: S1.1: Substrate preparation: Before vacuum deposition, the surface of the thin film substrate is cleaned to remove organic impurities and contaminants. Then, the thin film substrate is thermally annealed to relieve stress. Finally, a relatively pure oxide substrate is formed on the surface of the thin film substrate. S1.2: Vacuum system preparation: Clean the inside of the vacuum chamber to ensure it is free of dust and impurities, install a suitable reaction chamber and heating source, ensure the atmosphere in the reaction chamber is dry and oxygen-free, and reduce the gas pressure to the required range by vacuum pumping. S1.3: Vacuum deposition: The thin film substrate is placed in the reaction chamber for vacuum deposition. During the vacuum deposition process, appropriate deposition parameters are controlled. S1.4: Post-processing: After deposition, the order and crystallinity of the perovskite thin film crystals are further improved by thermal annealing. Then, light annealing or laser annealing is used to reasonably control the impurity content during the deposition process and further optimize crystallinity and impurity removal. S1.5: Result Characterization: The crystallinity of the perovskite film was characterized and analyzed using X-ray diffraction (XRD) or scanning electron microscopy (SEM). S2: Screening of perovskite films: Based on the crystallinity analysis results of S1.5, perovskite films with incomplete crystallization are screened from the perovskite films prepared in S1. S3: Dissolve the halide in solvent A to prepare a reaction solution with a total solute concentration of 0-5 mol / L; S4: Place the incompletely crystallized perovskite films selected in S2 onto a substrate stage in a sealed vacuum chamber. The vacuum level of the chamber is controlled to be 5*10⁻⁶ using a vacuum pump. -4 -5*10 4 Pa; S5: The reaction liquid in S3 is converted into an atomized reaction liquid using an ultrasonic atomizing device. The atomized reaction liquid is then carried into the vacuum chamber in S4 by a carrier gas. The vacuum environment allows the atomized reaction liquid to be rapidly and evenly distributed and act on the surface and interior of the vacuum-deposited perovskite film that is not fully crystallized. After annealing, it can be recrystallized and then grown again to obtain a highly crystalline, uniform and dense perovskite film.

2. The method for improving the crystallinity of vacuum-deposited perovskite thin films according to claim 1, characterized in that, In S1.1, the thin film substrate can be cleaned using a cleaning agent, solvent, or ultrasonic cleaning method. The oxide substrate uses zirconium oxide or aluminum oxide as the main substrate and also includes nickel oxide, tin oxide, organic monolayer, and polymer.

3. The method for improving the crystallinity of vacuum-deposited perovskite thin films according to claim 1, characterized in that, In S1.3, the deposition parameters include deposition temperature, deposition rate, gas flow rate, and atmosphere composition.

4. The method for improving the crystallinity of vacuum-deposited perovskite thin films according to claim 1, characterized in that, In S3, the halide is one or a mixture of two or more of the following: methyl iodine, methyl chloromethamine, methyl bromide, formamidine iodomethacin, cesium chloride, cesium iodide, cesium bromide, and rubidium chloride.

5. The method for improving the crystallinity of vacuum-deposited perovskite thin films according to claim 4, characterized in that, In S3, solvent A is one or a mixture of two or more of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, γ-butyrolactone, N,N-dimethylpropenylurea, N,N-dimethylacetamide, isopropanol, and water.

6. The method for improving the crystallinity of vacuum-deposited perovskite thin films according to claim 1, characterized in that, In step S5, the carrier gas is nitrogen, argon, or dry air.

7. The preparation method for improving the crystallinity of vacuum-deposited perovskite thin films according to claim 6 and its application, characterized in that, In step S5, the substrate stage temperature is controlled at 25-300℃, the atomizing gas flow rate is 0.1-30mL / min, and the reaction time is 0.1-120min.

8. The application of the perovskite thin film prepared by the method for improving the crystallinity of vacuum-deposited perovskite thin films according to any one of claims 1-7, characterized in that, The perovskite thin film can be used as a light-absorbing layer in solar cell modules.

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