Large-area perovskite thin film preparation method based on humidity dynamic regulation and control

Abstract

The invention relates to a large-area perovskite thin film preparation method based on humidity dynamic regulation and control. The method sequentially comprises the following steps: preparing a perovskite precursor main solution; dynamically adjusting the addition amount of ammonium chloride according to the real-time relative humidity in the air environment, wherein the addition amount of ammonium chloride is 1-25% of the molar weight of perovskite; adding ammonium chloride into the perovskite precursor main solution to obtain a perovskite precursor solution; coating the perovskite precursor solution on a large-area substrate to form a wet film; carrying out vacuum flash evaporation treatment on the wet film; and carrying out thermal annealing treatment on the thin film subjected to vacuum flash evaporation treatment to form the perovskite thin film. After the MACl is dynamically added, the grain orientation degree of the perovskite thin film is improved by 30% or above, the grain size is increased to 500-1000 nm, and the pinhole rate is reduced to be smaller than or equal to 1%.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, and in particular to a method for preparing large-area perovskite thin films based on dynamic humidity control. Background Technology

[0002] Perovskite solar cells, as a third-generation photovoltaic technology, have achieved a photoelectric conversion efficiency exceeding 27% for small-sized laboratory devices. The core bottleneck in industrialization lies in the preparation efficiency and cost control of large-area thin films. Solution methods, due to their simplicity and strong compatibility, have become the mainstream preparation technology for large-area perovskite thin films. Among them, the "vacuum flash evaporation process" effectively solves the problem of film uniformity by rapidly removing solvent under low pressure, and is currently a key development direction for mass production lines.

[0003] Perovskite solar cells (PSCs), as a third-generation photovoltaic technology, have attracted much attention due to their high photoelectric conversion efficiency, low-cost solution processing, and flexible fabrication capabilities. The key to their commercial application lies in solving the challenges of large-area fabrication and processing in atmospheric environments. Moisture and oxygen in the air interfere with the perovskite crystallization process, leading to decreased film quality and increased defects. Additive engineering is an effective means to improve perovskite crystallization, among which methylammonium chloride (MACl) is widely used because it promotes crystallization and increases grain size. Meanwhile, vacuum flash evaporation technology, a key process for large-area perovskite thin film fabrication that has emerged in recent years, can effectively improve film quality by rapidly removing solvents.

[0004] In existing technologies, the application of MACl in the regulation of perovskite crystallization has been widely reported, but all have significant limitations, as follows: Dominated by an inert atmosphere, with poor adaptability to various air environments: For example, Chinese patent CN114204328A (publication date 2022.03.18) discloses "a method for preparing MACl-modified perovskite thin films," the core of which is to add a fixed amount (5 mol%) of MACl to the precursor under an inert N2 atmosphere, which can improve the small area (0.1 cm²) of perovskite film. 2 The device efficiency was calculated, but the interference of moisture / oxygen in the air environment was not considered. When applied directly to the air environment, the thin film pinhole rate increased to more than 8%, and the efficiency decreased by 30%.

[0005] The fixed amount added cannot cope with humidity fluctuations. The paper "MACl-Assisted Crystallization of Perovskite Films for Efficient Solar Cells" published in *Advanced Energy Materials*, Volume 11, Issue 3, 2021, reports that adding a fixed amount (10 mol%) of MACl to an air environment (uncontrolled humidity, approximately 25% RH) resulted in the formation of films over a small area (0.5 cm²). 2 The thin film grain size can reach 1μm, but when the humidity rises to 40% RH, the fixed addition amount leads to the formation of MA4PbCl6 secondary phase, and the device efficiency drops from 21% to 15%; when the humidity drops to 10% RH, the fixed addition amount cannot fully suppress rapid nucleation, and the grain size shrinks to 400nm.

[0006] Focusing on small areas, there is a lack of process adaptability for large areas: Existing technologies all have a thickness of ≤1cm 2 This study focuses on small-area substrates and does not consider issues such as uneven solvent evaporation and humidity gradient differences in large-area preparation (e.g., slot coating, inkjet printing). For example, the MACl addition scheme disclosed in US Patent 11355678B2 (granted on June 7, 2022) is used in 10cm substrates. 2 When applied to large-area substrates, the grain size difference between the edge and the center reaches 500nm, and the pinhole rate rises to 12%, which cannot meet the uniformity requirements of the components.

[0007] In summary, the shortcomings of existing technologies are as follows: Unable to dynamically respond to fluctuations in air humidity: Existing technologies use a "fixed MACl addition amount," but the humidity (RH) in the air environment often fluctuates between 10% and 50%. Insufficient fixation at low humidity will lead to rapid nucleation (small grains), while excessive fixation at high humidity will lead to the formation of secondary phases (MA4PbCl6), neither of which can achieve the optimal crystal quality.

[0008] Poor crystallization uniformity during large-area preparation: Existing technologies do not address the issues of solvent evaporation gradient and humidity distribution differences in large-area coatings, resulting in significant differences (>30%) in crystallinity and grain size between the film edge and center, and a high pinhole rate (>5%), which fails to meet the requirements for consistent component performance.

[0009] Performance degrades in high humidity environments: In environments with high humidity (>30% RH), a fixed amount of MACl cannot effectively suppress the negative effects of moisture and is still prone to problems such as small grain size (<500nm), random orientation, and high pinhole rate (>5%).

[0010] Potential stability issues: Existing solutions fail to effectively suppress perovskite decomposition caused by moisture, affecting the long-term stability of the modules and causing rapid performance degradation in high-temperature and high-humidity environments.

[0011] In view of the above-mentioned shortcomings, the designer actively researched and innovated in order to create a method for preparing large-area perovskite thin films based on dynamic humidity control, so as to make it more valuable for industrial applications. Summary of the Invention

[0012] To address the aforementioned technical problems, the present invention aims to provide a method for preparing large-area perovskite thin films based on dynamic humidity control.

[0013] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing large-area perovskite thin films based on dynamic humidity control includes the following steps: Step 1: Prepare the perovskite precursor master solution; Step 2: Dynamically adjust the amount of ammonium methyl chloride added according to the real-time relative humidity in the air environment. The amount of ammonium methyl chloride added is 1% to 25% of the molar amount of perovskite. Step 3: Add ammonium methyl chloride to the perovskite precursor main solution to obtain the perovskite precursor solution; Step 4: Coat the perovskite precursor solution onto a large-area substrate to form a wet film; Step 5: Perform vacuum flash evaporation on the wet film; Step 6: Perform thermal annealing on the vacuum flash evaporation film to form a perovskite film.

[0014] As a further improvement of the present invention, the dynamic adjustment of the amount of ammonium methyl chloride added in step 2 is specifically as follows: When the relative humidity of the air environment is ≤20%, the amount of ammonium methyl chloride added is 15%~25% of the molar amount of perovskite; When the relative humidity of the air environment is between 20% and 35%, the amount of methyl ammonium chloride added is 10% to 20% of the molar amount of perovskite. When the relative humidity of the air environment is between 35% and 50%, the amount of methyl ammonium chloride added is 1% to 10% of the molar amount of perovskite.

[0015] As a further improvement of the present invention, the addition of ammonium chloride in step 3 can be either a blending addition method or a delayed addition method; when the relative humidity of the air environment is greater than 35%, the delayed addition method is adopted; when the relative humidity of the air environment is less than or equal to 35%, the conventional blending addition method or the delayed addition method is adopted.

[0016] As a further improvement of the present invention, the blending addition method is as follows: first, dissolve ammonium chloride in a mixed solvent of DMF and NMP to prepare a mother liquor with a concentration of 0.1~2 mol / L, and then add the mother liquor to the perovskite precursor main solution and stir together for 1~2 hours to ensure uniform dispersion.

[0017] As a further improvement of the present invention, the delayed addition method is as follows: first, prepare the perovskite precursor main solution and stir until completely dissolved, then add the ammonium chloride mother liquor 10 to 60 minutes before the coating operation, and stir at a speed of 100 to 300 rpm for 5 to 15 minutes before coating.

[0018] As a further improvement of the present invention, the coating method in step 4 is any one of slot coating, scraping coating and inkjet printing.

[0019] As a further improvement of the present invention, the vacuum flash evaporation process in step 5 is specifically as follows: the ambient pressure is reduced to below 10 Pa within 10 seconds and the pressure is maintained for 60 to 100 seconds.

[0020] As a further improvement of the present invention, the temperature of the heat annealing treatment in step 6 is 90~110°C and the time is 20~40 minutes.

[0021] As a further improvement of the present invention, the general chemical formula of the perovskite precursor in step 1 is: A (1-x-y) MA x FA y Pb(I (1-n-m) Br n Cl m )3+k additive; where A is a monovalent inorganic cation, MA is methylammonium ion, FA is formamidinium ion, additive is methylammonium chloride or other crystallization regulator, and x, y, n, m, and k are all molar coefficients, and 0 <x,y,n,m,k<1。

[0022] As a further improvement of the present invention, the perovskite precursor mixed solvent system in step 1 is DMF:NMP = 5~9:1.

[0023] By means of the above-described solution, the present invention has at least the following advantages: Significantly improves crystal quality: After dynamically adding MACl, the grain orientation of the perovskite film is increased by more than 30%, the grain size increases to 500~1000nm, and the pinhole rate is reduced to ≤1%.

[0024] Enhanced environmental stability: Effectively suppresses the negative impacts of moisture and oxygen during the crystallization process, improving the efficiency stability of the components after aging tests.

[0025] Excellent process adaptability and repeatability: This method is perfectly adaptable to all large-area coating processes in air environments (such as slot coating, blade coating, inkjet printing), and is suitable for 30... 30 cm, 0.6 Available in various sizes, including 1.2 m, it offers high practicality and operability.

[0026] Reduced costs and increased efficiency: It avoids the need for complex environmental control systems, reduces equipment investment and operating costs, and improves production efficiency and the consistency of large-area films.

[0027] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the following are preferred embodiments of the present invention described in detail with reference to the accompanying drawings. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic flowchart of a method for preparing large-area perovskite thin films based on dynamic humidity control according to the present invention. Figure 2 This is a schematic diagram of the thin film as a comparative example of the present invention; Figure 3 This is a schematic diagram of the thin film according to the third embodiment of the present invention; Figure 4 The morphology of the thin film in the comparative example of this invention is shown. Figure 1 ; Figure 5 The morphology of the thin film in the comparative example of this invention is shown. Figure 2 ; Figure 6 This is an XRD pattern of the thin film used as a comparative example of the present invention; Figure 7 The morphology of the thin film according to the third embodiment of the present invention Figure 1 ; Figure 8 The morphology of the thin film according to the third embodiment of the present invention Figure 2 ; Figure 9 This is an XRD pattern of the thin film according to the third embodiment of the present invention; Figure 10 These are the JV curves of the perovskite solar cell modules of the comparative example and the third embodiment of the present invention. Detailed Implementation

[0030] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0031] To enable those skilled in the art to better understand the present invention, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0032] First embodiment of the present invention: I. A method for preparing large-area perovskite thin films based on dynamic humidity control in this embodiment (e.g.) Figure 1 As shown), the steps are as follows: Step 1: Prepare the perovskite precursor master solution.

[0033] The general chemical formula of the perovskite precursor in step 1 is: A (1-x-y) MA x FA y Pb(I (1-n-m) Br n Cl m )3+kadditive; where A is a monovalent inorganic cation, MA is methylammonium ion, FA is formamidinium ion, additive is methylammonium chloride or other crystallization regulator, and x, y, n, m, and k are all molar coefficients, and 0 <x,y,n,m,k<1。

[0034] The perovskite precursor mixed solvent system in step 1 is DMF:NMP = 5~9:1.

[0035] Step 2: Dynamically adjust the amount of ammonium methyl chloride added according to the real-time relative humidity in the air environment. The amount of ammonium methyl chloride added is 1% to 25% of the molar amount of perovskite.

[0036] The specific steps for dynamically adjusting the amount of ammonium methyl chloride added in step 2 are as follows: When the relative humidity of the air environment is ≤20%, the amount of ammonium methyl chloride added is 15%~25% of the molar amount of perovskite; When the relative humidity of the air environment is between 20% and 35%, the amount of methyl ammonium chloride added is 10% to 20% of the molar amount of perovskite. When the relative humidity of the air environment is between 35% and 50%, the amount of methyl ammonium chloride added is 1% to 10% of the molar amount of perovskite.

[0037] Step 3: Add ammonium methyl chloride to the perovskite precursor main solution to obtain the perovskite precursor solution.

[0038] In step 3, ammonium chloride is added either by blending or by delay. When the relative humidity of the air environment is greater than 35%, the delayed addition method is used; when the relative humidity of the air environment is less than or equal to 35%, the conventional blending or delayed addition method is used.

[0039] The blending method is as follows: first, dissolve ammonium chloride in a mixed solvent of DMF and NMP to prepare a mother liquor with a concentration of 0.1~2 mol / L, then add the mother liquor to the perovskite precursor main solution and stir together for 1~2 hours to ensure uniform dispersion.

[0040] The delayed addition method is as follows: first, prepare the perovskite precursor main solution and stir until completely dissolved. Then, add the ammonium methyl chloride mother liquor 10-60 minutes before the coating operation, stir at 100-300 rpm for 5-15 minutes, and then immediately carry out the coating.

[0041] Traditional blending methods result in MACl participating in the reaction too early, making it susceptible to moisture interference in the air. "Delayed addition," by introducing MACl shortly before coating, reduces its exposure to air, effectively lowering the probability of side reactions and ensuring the purity and controllability of the crystallization process under high humidity. This distinguishes it from existing techniques that involve preparation under inert atmospheres or specific conditions.

[0042] Step 4: Coat the perovskite precursor solution onto a large-area substrate to form a wet film.

[0043] The coating method in step 4 can be any one of slot coating, scraping, and inkjet printing.

[0044] Step 5: Perform vacuum flash evaporation on the wet film.

[0045] The vacuum flash evaporation process in step 5 specifically involves: reducing the ambient pressure to below 10 Pa within 10 seconds and maintaining the pressure for 60-100 seconds.

[0046] Step 6: Perform thermal annealing on the vacuum flash evaporation film to form a perovskite film.

[0047] The temperature of the heat annealing treatment in step 6 is 90~110℃, and the time is 20~40 minutes.

[0048] The synergy between "dynamic MACl addition" and "vacuum flash evaporation": Dynamically adjusted MACl creates optimal thermodynamic conditions for crystallization, while the subsequent vacuum flash evaporation (e.g., evaporating to 10 Pa in 10 s and holding at that pressure for 40-100 s) rapidly removes the solvent, locking in the "instantaneous state" of the precursor solution and suppressing component segregation caused by excessive solvent evaporation, which is crucial for the uniformity of large-area films. The combination of these two techniques achieves a perfect unity of "thermodynamic optimization" and "kinetic locking."

[0049] Synergy between "delayed addition" and "vacuum flash evaporation": Delayed addition ensures that MACl is precisely introduced at the last moment, while vacuum flash evaporation immediately "fixes" the optimized solution state. This "tight timing" greatly improves the repeatability and stability of the process, especially in high humidity environments.

[0050] The entire process chain in this embodiment—humidity adaptive decision-making, precise MACl addition (including timing selection), large-area coating, rapid curing via vacuum flash evaporation, and thermal annealing crystallization—is interconnected, forming a dedicated process package for large-area fabrication in air environments. The overall technical benefits (improved uniformity, pinhole rate, and stability) far exceed the simple sum of the effects of each individual step. This method combines the efficiency of solution processing with the precision of vacuum treatment, contributing to improved film quality.

[0051] II. The core technology of this embodiment lies in: adding MACl (methylammonium chloride) to the perovskite precursor solution, and dynamically adjusting the amount added according to the relative humidity (RH) of the air environment. (1) General formula of perovskite precursor The chemical formula of the perovskite precursor is represented by the general formula: A (1-x-y) MA x FA y Pb(I (1-n-m) Br n Cl m )3+k additive in: A represents a monovalent inorganic cation (such as Cs). + 、Rb + wait).

[0052] MA represents methylammonium ion (CH3NH3) + ).

[0053] FA represents formamidinium ion (CH(NH2)2) + ).

[0054] x, y, n, m, and k are all molar coefficients, and 0 <x,y,n,m,k<1。

[0055] The additive can be MACl or other crystallization regulators.

[0056] (2) Adding a proportional range and dynamic adjustment strategy to MACl The amount of MACl added is 1% to 25% of the molar weight of the perovskite, and the specific amount should be dynamically adjusted according to the real-time ambient humidity. (3) Two ways to add MAC1 This invention provides two methods for adding MACl, which can be selected according to process requirements: Blending addition: First, dissolve MACl in a DMF-based mixed solvent to prepare a stock solution with a concentration of 0.1~2 mol / L. Then, add the stock solution to the perovskite precursor main solution and stir together for 1~2 hours to ensure uniform dispersion.

[0057] Delayed addition (add before coating): Prepare the perovskite precursor master solution and stir until completely dissolved. Add the MACl stock solution 10-60 minutes before the coating operation, and stir gently (100-300 rpm) for 5-15 minutes before coating. This method can reduce premature reaction of MACl with the environment and is particularly suitable for high humidity environments.

[0058] (4) Large-area preparation process flow as follows Figure 1 As shown.

[0059] (5) Mechanism of action Cl - Function: It occupies iodine vacancies in the perovskite lattice, inhibiting nonradiative recombination.

[0060] MA + Function: Adsorbed on the surface of crystal nuclei, it slows down the crystal growth rate and promotes the formation of larger and more regular crystals.

[0061] Reaction with H2O: MACl can react with trace amounts of moisture in the environment to generate HCl, which inhibits the hydrolysis of perovskite materials.

[0062] Intermediate phase regulation: MACl participates in the formation of intermediate phases such as MACl-PbI2-DMSO, which lowers the crystallization energy barrier and guides the formation of high-quality perovskite phases.

[0063] First experimental example of the present invention: 30°C in a low humidity environment (≤20% RH) Preparation of 30cm components Environmental conditions: Temperature 25℃, Humidity 18% RH.

[0064] Precursor formulation: Cs 0.17 FA 0.83 PbI3 Solvent system: DMF: NMP = 7:1.

[0065] MACl addition: The conventional blending method was used to add 25% of the molar amount of perovskite in MACl (prepared as a 1.0 mol / L stock solution).

[0066] Film formation process: slot coating (30 After 30 cm substrate, vacuum flash evaporation (evacuation to 10 Pa in 10 s, holding pressure for 60 s), followed by annealing at 100 °C for 30 minutes.

[0067] Results: The thin film has a good mirror effect. SEM shows a grain size of 800~1000nm, XRD shows a strong (110) orientation, and the pinhole rate is <0.5%.

[0068] Second experimental example of the present invention: 0.6 in a moderate humidity environment (20-35% RH) Preparation of 1.2m Components Environmental conditions: Temperature 24℃, Humidity 25% RH.

[0069] Precursor formulation: Same as in the first experimental example.

[0070] Solvent system: DMF: NMP = 7:1.

[0071] MACl addition: Using a delayed addition method, add 15% of the molar amount of perovskite in MACl stock solution (1.0 mol / L) 30 minutes before coating, and stir gently (200 rpm) for 10 minutes.

[0072] Film formation process: Slit coating (0.6) After evaporating the substrate to 1.2 m, the substrate was subjected to vacuum flash evaporation (evacuated to 10 Pa in 10 s, held at pressure for 80 s) and annealed at 100 °C for 30 minutes.

[0073] Results: The film surface was uniform and had good crystallinity.

[0074] The third experimental example of the present invention: In a high humidity environment (35-50% RH) for 30 Preparation of 30cm components Environmental conditions: Temperature 23℃, Humidity 42% RH.

[0075] Precursor formulation: Same as in the first experimental example.

[0076] Solvent system: DMF: NMP = 7:1.

[0077] MACl addition: A delayed addition method was used, adding 8% of the molar amount of perovskite in MACl stock solution (0.5 mol / L) 20 minutes before coating, and stirring gently (150 rpm) for 15 minutes.

[0078] Film formation process: slot coating (30 After 30 cm substrate, vacuum flash evaporation (evacuation to 10 Pa in 10 s, holding pressure for 60 s), followed by annealing at 100 °C for 30 minutes.

[0079] like Figure 3 , Figures 7-9 As shown: Results: No obvious fogging was observed on the film surface; the film surface was uniform and exhibited good crystallinity.

[0080] Comparative examples of the present invention: Adverse effects of excessive MACl in high humidity environments Environmental conditions: Temperature 23℃, Humidity 45%RH Precursor formulation: Same as in the first experimental example. Solvent system: DMF: NMP = 7:1 MACl addition: A delayed addition method was used, adding 25% of the molar amount of perovskite in MACl stock solution (1.0 mol / L) 30 minutes before coating, and stirring gently (200 rpm) for 10 minutes. Film formation process: Same as the first experimental example like Figure 2 , Figures 4-6 As shown: Results: The film surface was obviously hazy with poor mirror effect. SEM showed uneven crystallization and very small grains. XRD results showed poor crystallization quality.

[0081] like Figure 10 The JV curves of the perovskite solar cell modules in the comparative example and the third embodiment of the present invention are shown, and their photovoltaic performance parameters are statistically summarized in the following table: I. A brief summary of the experimental results of the above experimental examples and comparative examples: 1. The comparative examples demonstrate the failure of the "fixed addition amount" approach: A fixed and excessive amount of MACl (25%) was used, which proved effective in the first experimental example (low humidity). The results showed a significant decrease in film fogging, poor crystallinity, and all device performance parameters. This comparative example strongly refutes the conventional approach of "simply using the optimal formulation under inert atmosphere or low humidity." It demonstrates that a fixed addition strategy that ignores humidity is not feasible in an air environment, thus highlighting the real and serious technical problem that this invention aims to solve.

[0082] 2. Analysis of the results of the third experimental case: The core strategy of this invention was adopted: dynamically reducing the amount of MCAP added (8%) and using a delayed addition method. The film quality was excellent, and the device efficiency (21.36%) was much higher than that of the comparative example (18.44%). In particular, the significant improvement in the fill factor (FF) directly reflects the improvement in the crystal quality of the film and the reduction in internal recombination. This forms a stark contrast with the comparative example, which is a "controlled variable" approach. It directly proves the effectiveness and non-obviousness of the specific technical means of "reducing the amount of MCAP added under high humidity and combining it with delayed addition".

[0083] 3. The first and second experimental examples demonstrate the universality of this scheme: This demonstrates that the present invention is not only applicable to high humidity, but is a complete adaptive system covering the entire humidity range.

[0084] The first experimental case demonstrated the effectiveness of a higher addition level (25%) under low humidity conditions.

[0085] Second experimental example: Demonstrated that under moderate humidity, a moderate addition amount (15%) and delayed addition are effective for ultra-large areas (0.6%). Feasibility of preparation (1.2m).

[0086] II. Analysis of the synergy of the above technical features: 1. "Low addition amount" vs. "delayed addition" Under high humidity, a large number of water molecules in the environment will compete with MACl for reaction. If the amount of MACl added is too high (comparative example), it will react with environmental water vapor and precursors in large quantities and rapidly, leading to rapid nucleation and the generation of a large number of fine, disordered grains.

[0087] This invention reduces the total amount of reactants at the source by using a "low addition amount," while simultaneously shortening the time that MACl is exposed to a humid environment by using "delayed addition." These two methods work synergistically to precisely control the driving force and kinetics of crystallization, making the crystallization process "slow down and become more orderly," thereby obtaining large-sized, highly oriented grains.

[0088] 2. "Dynamic Addition Strategy" and "Large-Area Preparation" Large-area components (such as 0.6 in the second experimental example) When prepared in air (1.2m), different areas will face small humidity gradients. A fixed amount of additive will amplify this non-uniformity.

[0089] The dynamic strategy of this invention ensures that the amount of MACl added is an optimal solution based on the overall ambient humidity over a large area, which guarantees the uniformity of the film at the system level, something that has not been addressed by existing technologies.

[0090] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0091] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles 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 method for preparing large-area perovskite thin films based on dynamic humidity control, characterized in that, The steps are as follows: Step 1: Prepare the perovskite precursor master solution; Step 2: Dynamically adjust the amount of ammonium methyl chloride added according to the real-time relative humidity in the air environment. The amount of ammonium methyl chloride added is 1% to 25% of the molar amount of perovskite. Step 3: Add ammonium methyl chloride to the perovskite precursor main solution to obtain the perovskite precursor solution; Step 4: Coat the perovskite precursor solution onto a large-area substrate to form a wet film; Step 5: Perform vacuum flash evaporation on the wet film; Step 6: Perform thermal annealing on the vacuum flash evaporation film to form a perovskite film.

2. The method for preparing large-area perovskite thin films based on dynamic humidity control as described in claim 1, characterized in that, The specific steps for dynamically adjusting the amount of ammonium methyl chloride added in step 2 are as follows: When the relative humidity of the air environment is ≤20%, the amount of ammonium methyl chloride added is 15%~25% of the molar amount of perovskite; When the relative humidity of the air environment is between 20% and 35%, the amount of methyl ammonium chloride added is 10% to 20% of the molar amount of perovskite. When the relative humidity of the air environment is between 35% and 50%, the amount of methyl ammonium chloride added is 1% to 10% of the molar amount of perovskite.

3. The method for preparing large-area perovskite thin films based on dynamic humidity control as described in claim 1, characterized in that, In step 3, ammonium chloride is added either by blending or by delay. When the relative humidity of the air environment is greater than 35%, the delayed addition method is used; when the relative humidity of the air environment is less than or equal to 35%, the conventional blending or delayed addition method is used.

4. The method for preparing large-area perovskite thin films based on dynamic humidity control as described in claim 3, characterized in that, The blending method is as follows: first, dissolve ammonium chloride in a mixed solvent of DMF and NMP to prepare a mother liquor with a concentration of 0.1~2 mol / L, and then add the mother liquor to the perovskite precursor main solution and stir together for 1~2 hours to ensure uniform dispersion.

5. The method for preparing large-area perovskite thin films based on dynamic humidity control as described in claim 3, characterized in that, The delayed addition method is as follows: first, prepare the perovskite precursor main solution and stir until completely dissolved, then add the ammonium chloride mother liquor 10-60 minutes before the coating operation, and stir at 100-300 rpm for 5-15 minutes before coating.

6. The method for preparing large-area perovskite thin films based on dynamic humidity control as described in claim 1, characterized in that, The coating method in step 4 is any one of slot coating, scraping, and inkjet printing.

7. The method for preparing large-area perovskite thin films based on dynamic humidity control as described in claim 1, characterized in that, The vacuum flash evaporation process in step 5 specifically involves: reducing the ambient pressure to below 10 Pa within 10 seconds and maintaining the pressure for 60-100 seconds.

8. The method for preparing large-area perovskite thin films based on dynamic humidity control as described in claim 1, characterized in that, The temperature of the heat annealing treatment in step 6 is 90~110℃, and the time is 20~40 minutes.

9. The method for preparing large-area perovskite thin films based on dynamic humidity control as described in claim 1, characterized in that, The general chemical formula of the perovskite precursor in step 1 is: A (1-x-y) MA x FA y Pb(I (1-n-m) Br n Cl m )3+kadditive; where A is a monovalent inorganic cation, MA is methylammonium ion, FA is formamidinium ion, additive is methylammonium chloride or other crystallization regulator, and x, y, n, m, and k are all molar coefficients, and 0 <x,y,n,m,k<1。 10. The method for preparing large-area perovskite thin films based on dynamic humidity control as described in claim 1, characterized in that, The perovskite precursor mixed solvent system in step 1 is DMF:NMP = 5~9:1.

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