Perovskite thin film solvent, precursor solution, thin film, preparation method and battery

Abstract

The invention relates to a perovskite thin film solvent, a precursor solution, a thin film, a preparation method and a battery. The perovskite thin film solvent is a ternary mixed solvent composed of a main solvent, a coordination adjusting solvent and an accelerated desorption agent; the main solvent is N, N-dimethylformamide; the coordination adjusting solvent is N-methyl pyrrolidone; the accelerated desorption agent is selected from at least one of 2-methoxyethanol, acetonitrile or isopropanol. The flash evaporation efficiency is remarkably improved, the production capacity is doubled, the vacuum flash evaporation time is shortened to 20-40 seconds from 40-100 seconds, the capacity per hour of a 30 * 30 cm substrate single cavity is improved to 240 pieces from 120 pieces, the capacity per hour of a 0.6 * 1.2 m substrate is improved to 120 pieces from 60 pieces, and the requirements of a mass production line are completely met.

Description

Technical Field

[0001] This invention relates to the field of perovskite battery technology, and in particular to a perovskite thin film solvent, precursor solution, thin film, preparation method, and battery. 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 their industrialization lies in the efficiency and cost control of large-area thin-film fabrication. Solution methods, due to their simplicity and strong compatibility, have become the mainstream fabrication technology for large-area perovskite thin films. Among them, the "vacuum flash evaporation process," with its advantage of rapid solvent removal under low pressure, can effectively solve the problem of film uniformity and is currently a key development direction for mass production lines.

[0003] Solvent engineering is a core component of the vacuum flash evaporation process: a high-quality solvent system must simultaneously satisfy both "strong coordination ability (ensuring film quality)" and "high desorption efficiency (reducing residue and energy consumption)." Previously developed DMF (N,N-dimethylformamide)-NMP (N-methylpyrrolidone) binary solvent systems (such as the prior core patent solution) have solved the problems of high residue and film fogging in traditional DMF-DMSO systems, but still face the pain points of "long vacuum flash evaporation time and high process energy consumption" in industrial applications, hindering the improvement of production efficiency (e.g., flash evaporation time for 30×30cm substrates requires 40~100 seconds, with a single chamber hourly capacity of only about 120 pieces; flash evaporation time for 0.6×1.2m substrates needs to be increased to 90~180 seconds).

[0004] Existing technology 1 discloses a DMF-NMP binary mixed solvent system, wherein the volume ratio of DMF to NMP is 4:1 to 9:1 (preferably 6:1 to 8:1), the water content is ≤50ppm, and it is suitable for 0.8-1.6mol / L perovskite precursors; the vacuum flash evaporation process parameters are vacuum degree <10Pa, holding time 40-100 seconds, and annealing temperature 100-150℃. This system can achieve solvent residue ≤0.5%, but it suffers from the problem of excessively long flash evaporation time (more than 50 seconds for a 30×30cm substrate) and slow process, making it difficult to meet the demand of mass production lines for "hourly capacity ≥200 wafers".

[0005] Existing technology 2: Patent CN114792762A: discloses a method for preparing perovskite thin films under vacuum conditions, mentioning NMP as an "auxiliary ligand" to adjust the crystallization rate (the amount used is only less than 5% of the total solvent), but does not involve "adding a third component to the DMF-NMP system to shorten the flash evaporation time", and does not pay attention to the energy consumption issue.

[0006] Existing technology 3: Patent CN115843204B: It adopts the DMF-DMSO binary system and accelerates DMSO desorption by increasing the annealing temperature (150-180℃). However, the high temperature leads to an increase in film defects and the energy consumption is 40% higher than that of the vacuum flash evaporation process.

[0007] Existing technology 4: Journal article "Solar Energy Materials & Solar Cells" Volume 262, 2024: reported "vacuum flash evaporation kinetics of DMF-NMP binary system". Experimental data showed that the solvent desorption half-life of this system was 28 seconds at a vacuum of 5 Pa and a temperature of 100 °C. It was necessary to hold the pressure for 50 seconds to reduce the residual amount to 0.5%. Further shortening the time would cause the residual amount to rise to more than 1%, which would increase the risk of film fogging.

[0008] In summary, the shortcomings of existing technologies are: Vacuum flash evaporation has a long time and low production efficiency: In the DMF-NMP binary system, NMP has a high boiling point (202℃), and the desorption rate of the mixed solvent formed with DMF is slow. The flash evaporation time for a 30×30cm substrate is 40-100 seconds, and for a 0.6×1.2m large-area substrate, it is 90-180 seconds. The hourly production capacity of a single-cavity mass production line is difficult to exceed 150 pieces. High energy consumption and difficulty in cost control: Long flash evaporation time leads to continuous operation of the vacuum system (vacuum module), resulting in long flash evaporation time and high energy consumption per substrate; Limited adaptability for large areas: Due to the excessively long flash evaporation time, 0.6×1.2m substrates are prone to "higher solvent residue at the edges" (the flash evaporation time at the edges is 10-15 seconds longer than that at the center), which causes the film thickness uniformity error to rise to 6%-8%, exceeding the industrialization requirements (≤5%).

[0009] In view of the above-mentioned shortcomings, the designer has actively conducted research and innovation in order to create a perovskite thin film solvent, precursor solution, thin film and preparation method, and battery, so as to make it more industrially valuable. Summary of the Invention

[0010] To address the aforementioned technical problems, the present invention aims to provide a perovskite thin film solvent, a precursor solution, a thin film, a preparation method thereof, and a battery.

[0011] To achieve the above objectives, the present invention adopts the following technical solution: One of the objectives of this invention is: A perovskite thin film solvent, comprising a ternary mixed solvent consisting of a main solvent, a coordination modifier solvent, and an accelerated desorption agent; The main solvent is N,N-dimethylformamide; The coordination modifier solvent is N-methylpyrrolidone; The desorption accelerating agent is selected from at least one of 2-methoxyethanol, acetonitrile or isopropanol, and its boiling point range is 80~150℃; The volume ratio of N,N-dimethylformamide to N-methylpyrrolidone is 4:1 to 9:1; The volume ratio of the accelerated desorption agent to the mixture of N,N-dimethylformamide and N-methylpyrrolidone is 0.05:1 to 1:1.

[0012] As a further improvement of the present invention, the volume ratio of N,N-dimethylformamide to N-methylpyrrolidone in the ternary mixed solvent is 6:1 to 8:1; and / or the volume ratio of the accelerated desorption agent to the mixture of N,N-dimethylformamide and N-methylpyrrolidone is 0.05:1 to 0.3:1.

[0013] As a further improvement of the present invention, the water content of N,N-dimethylformamide and N-methylpyrrolidone is ≤30ppm, and the total water content of the ternary mixed solvent is ≤50ppm.

[0014] The second objective of this invention is: A perovskite precursor solution is prepared by dissolving the perovskite precursor in a ternary mixed solvent as described above to form the perovskite precursor solution. The general chemical formula of the perovskite precursor is ABX3, wherein the A-site is a monovalent organic cation FA. + MA + or Cs + At least one of them, with the B site being Pb 2+ X is I - ,Br - or Cl - At least one of the following; the concentration of the perovskite precursor solution is 0.8~1.6 mol / L.

[0015] As a further improvement of the present invention, the perovskite precursor is (FAPbI3). 0.95 (MAPbBr3) 0.05 .

[0016] The third objective of this invention: A method for preparing a perovskite thin film includes the following steps: Step 1, perovskite precursor solution preparation steps: Prepare the perovskite precursor solution as described above; Step 2, Substrate Pretreatment: Select FTO / ITO substrates and perform ultrasonic cleaning and UV ozone cleaning; Step 3, Perovskite wet film coating step: The perovskite precursor solution from step 1 is coated onto the pretreated FTO / ITO substrate from step 2 using a slot coating method to form a wet film; wherein, the coating speed is 5~50mm / s. Step 4, Vacuum flash evaporation: Transfer the FTO / ITO substrate coated in step 3 to an environment with a vacuum degree of less than 10 Pa for vacuum flash evaporation, and hold pressure for 20~50 seconds; Step 5, Annealing and Crystallization: Transfer the flash-evaporated FTO / ITO substrate to an annealing furnace and anneal at 100~150℃ for 20~30 min, then allow it to cool naturally to room temperature to obtain a perovskite film.

[0017] As a further improvement of the present invention, the processing conditions in step 1 are as follows: under inert gas protection, N,N-dimethylformamide and N-methylpyrrolidone in a volume ratio of 4:1 to 9:1 are mixed and stirred for 8 to 12 minutes, then an accelerating desorption agent is slowly added and stirring is continued for 18 to 22 minutes; at room temperature of 25±2℃ and humidity ≤40%RH, the perovskite precursor is dissolved in a ternary mixed solvent, with a stirring speed of 600 to 1000 rpm and a stirring time of 2 to 4 hours to ensure that the perovskite precursor solute is completely dissolved.

[0018] As a further improvement of the present invention, in step 4, the vacuum degree is rapidly reduced to below 10 Pa within the initial 5 to 10 seconds of flash evaporation, and this vacuum degree is maintained until the pressure holding ends.

[0019] The fourth objective of this invention: A perovskite thin film is prepared by the method described above.

[0020] Fifth objective of this invention: A perovskite solar cell, wherein the light-absorbing layer is a perovskite thin film as described above.

[0021] By means of the above-described solution, the present invention has at least the following advantages: Flash evaporation efficiency has been significantly improved, and production capacity has doubled: the vacuum flash evaporation time has been shortened from 40~100 seconds to 20~40 seconds, the hourly production capacity of a single chamber for 30×30cm substrates has increased from 120 pieces to 240 pieces, and the production capacity of 0.6×1.2m substrates has increased from 60 pieces to 120 pieces, fully meeting the needs of mass production lines. Significantly reduced process energy consumption and controllable costs: Vacuum system operating time is shortened by 50%, and energy consumption per substrate flash evaporation is reduced; Maintaining the advantages of low residue and high-quality thin films: In the ternary system, low-boiling-point solvents preferentially evaporate to form "microchannels," promoting rapid desorption of DMF / NMP, with solvent residue ≤0.3% (GC-MS detection), further reduced compared to the binary system (≤0.5%); the thin film has good mirror effect, grain size 500~100nm, surface roughness Ra<20nm (AFM detection), and no haze phenomenon; Large-area uniformity is stable: the thickness uniformity error of the thin film on a 0.6×1.2m substrate is ≤5%, and the difference between the residual amount at the edge and the center is <0.1%, which solves the problem of "high edge residual" when preparing large areas of binary systems; Improved device performance and stability: The photoelectric conversion efficiency of the 30×30cm perovskite module prepared based on this system reaches 21%-22% (JV test, reverse scan). After aging for 1000 hours at 85℃ / 85% RH, the efficiency retention rate of the unencapsulated device is ≥85% (80% for the binary system).

[0022] 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

[0023] 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.

[0024] Figure 1 This is a schematic flowchart of a method for preparing a perovskite thin film according to the present invention; Figure 2 This is a morphology diagram of the perovskite thin film of the first experimental example of the present invention; Figure 3 This is the XRD curve of the perovskite thin film of the first experimental example of the present invention; Figure 4 This is the AFM characterization diagram of the perovskite thin film of the first experimental example of the present invention; Figure 5 This is a graph showing the roughness test results of the perovskite thin film in the first experimental example of the present invention. Figure 6 This is the JV curve of the perovskite solar cell module of the perovskite thin film of the first experimental example of the present invention. Figure 7 This is a morphology diagram of the perovskite thin film of the second experimental example of the present invention; Figure 8 This is the XRD curve of the perovskite thin film of the second experimental example of the present invention; Figure 9 This is the AFM characterization diagram of the perovskite thin film of the second experimental example of the present invention; Figure 10 This is a graph showing the roughness test results of the perovskite thin film in the second experimental example of the present invention; Figure 11This is the JV curve of the perovskite solar cell module of the perovskite thin film of the second experimental example of the present invention. Figure 12 This is a morphology diagram of the perovskite thin film in the comparative example of the present invention; Figure 13 This is an XRD pattern of a perovskite thin film, which is a comparative example of the present invention. Figure 14 This is the AFM characterization diagram of the perovskite thin film of the comparative example of the present invention; Figure 15 This is a graph showing the roughness test results of the perovskite thin film in the comparative example of this invention. Figure 16 This is the JV curve of a perovskite solar cell module based on the perovskite thin film of the present invention. Detailed Implementation

[0025] 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.

[0026] 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.

[0027] First embodiment of the present invention: This embodiment of a perovskite thin film solvent is a ternary mixed solvent composed of a main solvent, a coordination regulating solvent, and an accelerating desorption agent. The main solvent is N,N-dimethylformamide; The coordination modifier solvent is N-methylpyrrolidone; The desorption accelerating agent is selected from at least one of 2-methoxyethanol, acetonitrile or isopropanol, and its boiling point range is 80~150℃; The volume ratio of N,N-dimethylformamide to N-methylpyrrolidone is 4:1 to 9:1; The volume ratio of the accelerated desorption agent to the mixture of N,N-dimethylformamide and N-methylpyrrolidone is 0.05:1 to 1:1.

[0028] The volume ratio of N,N-dimethylformamide to N-methylpyrrolidone in the ternary mixed solvent is 6:1 to 8:1; and / or the volume ratio of the accelerated desorbent to the mixture of N,N-dimethylformamide and N-methylpyrrolidone is 0.05:1 to 0.3:1.

[0029] The water content of N,N-dimethylformamide and N-methylpyrrolidone is ≤30ppm, and the total water content of the ternary mixed solvent is ≤50ppm.

[0030] The composition of the ternary mixed solvent in this embodiment is shown in the table below: A brief description of the preparation method of ternary mixed solvents: Under the protection of an inert gas (nitrogen, purity ≥99.999%), DMF and NMP are first mixed in proportion and stirred for 10 minutes. Then, a low-boiling-point volatile solvent is slowly added and stirred for another 20 minutes.

[0031] The synergistic design of the ternary solvent system in this embodiment: by combining "DMF (main solvent) + NMP (coordination regulation) + low boiling point volatile solvent (accelerates desorption)", the problem of slow flash evaporation and high energy consumption of binary system is solved without sacrificing film formation quality.

[0032] Screening criteria for low-boiling-point volatile solvents (i.e., desorption accelerators): boiling point 80~150℃, completely miscible with DMF / NMP, does not react with perovskite precursors, and volume ratio controlled between 0.05:1 and 1:1 (to ensure synergistic desorption effect and avoid excessive amount leading to film defects).

[0033] In existing technologies, the use of additives typically focuses on a single function, such as improving crystal quality or enhancing stability. However, in this embodiment, the ternary solvent system, through functional division and synergistic effects, resolves the long-standing contradiction between "film formation quality and flash evaporation efficiency." DMF as the main solvent: provides the main dissolving ability for perovskite precursors, ensuring that the precursors are fully dissolved; NMP as a coordination modifier: with Pb 2+ To achieve appropriate coordination, regulate crystallization kinetics, and ensure film quality; Low-boiling-point solvents act as desorption accelerators: they preferentially evaporate under vacuum conditions, forming gas channels and promoting the desorption of high-boiling-point solvents.

[0034] This mechanism of desorption based on boiling point is unprecedented in existing technologies. It is not a simple additive process, but rather based on a deep understanding of the dynamic behavior of each component during vacuum flash evaporation. Experiments have shown that when the volume ratio of the low-boiling-point solvent to the DMF-NMP mixture is below 0.05:1, the acceleration effect is not significant; above 0.3:1, it leads to an increase in film defects. This optimal range was discovered in a way that cannot be easily obtained by those skilled in the art through conventional experiments.

[0035] The second embodiment of the present invention: This embodiment provides a perovskite precursor solution, which uses a ternary mixed solvent as described above to dissolve the perovskite precursor and form a perovskite precursor solution. The general chemical formula of the perovskite precursor is ABX3, where the A-site is a monovalent organic cation FA. + MA + or Cs + At least one of them, with the B site being Pb 2+ X is I - ,Br - or Cl - At least one of them.

[0036] The concentration of the perovskite precursor solution is 0.8~1.6 mol / L. A concentration <0.8 mol / L can easily lead to insufficient film thickness, while a concentration >1.6 mol / L can easily cause solute precipitation.

[0037] The perovskite precursor is (FAPbI3). 0.95 (MAPbBr3) 0.05 .

[0038] The preparation process was carried out at room temperature (25±2℃) and humidity ≤40% RH, with a stirring speed of 800 rpm and a stirring time of 3 hours to ensure complete dissolution of the solute.

[0039] The third embodiment of the present invention: like Figure 1 The method for preparing a perovskite thin film according to this embodiment includes the following steps: Step 1, perovskite precursor solution preparation steps: Prepare the perovskite precursor solution as described above.

[0040] The processing conditions in step 1 are as follows: Under inert gas protection, N,N-dimethylformamide and N-methylpyrrolidone in a volume ratio of 4:1 to 9:1 are mixed and stirred for 8 to 12 minutes. Then, an accelerating desorption agent is slowly added and stirring is continued for 18 to 22 minutes. The perovskite precursor is dissolved in a ternary mixed solvent at a room temperature of 25±2℃ and a humidity of ≤40%RH. The stirring speed is 600 to 1000 rpm and the stirring time is 2 to 4 hours to ensure that the perovskite precursor solute is completely dissolved.

[0041] Step 2, Substrate Pretreatment: Select FTO / ITO substrates ranging from 30×30cm to 0.6×1.2m, and clean them by ultrasonic cleaning (cleaning agent → deionized water, 15 minutes each), followed by UV ozone cleaning for 20 minutes (surface contact angle ≤15°).

[0042] Step 3, Perovskite wet film coating step: The perovskite precursor solution from step 1 is coated onto the pretreated FTO / ITO substrate from step 2 using a slot coating method to form a wet film; wherein, the coating speed is 5~50mm / s.

[0043] The liquid injection volume is adjusted according to the substrate area (250±10μL for 30×30cm substrate, 2000±50μL for 0.6×1.2m substrate) to ensure uniform wet film thickness (error ≤5%).

[0044] Step 4, Vacuum flash evaporation: Transfer the FTO / ITO substrate coated in step 3 to an environment with a vacuum degree of less than 10 Pa for vacuum flash evaporation, and hold pressure for 20~50 seconds.

[0045] In step 4, the vacuum level is rapidly reduced to below 10 Pa within the initial 5 to 10 seconds of flash evaporation, and this vacuum level is maintained until the pressure holding ends.

[0046] The vacuum level is controlled to be <10Pa (preferably <5Pa), and the pressure holding time is 20~40 seconds (20~40 seconds for 30×30cm substrate, 30~50 seconds for 0.6×1.2m substrate).

[0047] Step 5, Annealing and Crystallization: Transfer the flash-evaporated FTO / ITO substrate to an annealing furnace and anneal at 100~150℃ for 20~30 min, then allow it to cool naturally to room temperature to obtain a perovskite film.

[0048] This embodiment combines the desorption kinetics of the ternary mixed solvent system, shortening the holding time to 20-40 seconds, while ensuring a vacuum degree of <10Pa (balancing desorption efficiency and equipment cost).

[0049] The specific design of the step sequence in this embodiment: The innovative solvent mixing sequence: This embodiment requires that DMF and NMP be mixed and stirred for 10 minutes first, and then a low-boiling-point solvent be added and stirring continued for 20 minutes. This specific sequence ensures that the low-boiling-point solvent is introduced only after DMF and NMP have fully formed a coordination structure, thus avoiding interference from the low-boiling-point solvent in the formation of the DMF-NMP coordination structure when the three components are mixed simultaneously.

[0050] Creative approach to process step integration: This embodiment limits the transfer to the vacuum system immediately after coating (within 60 seconds). This time constraint ensures that the wet film enters the flash evaporation stage within the appropriate viscosity range. If the post-coating time is too long (>90 seconds), solvent evaporation will increase viscosity, significantly affecting the flash evaporation effect. This tight time control between steps, which has not been emphasized in the prior art, is one of the key innovations of this embodiment.

[0051] Synergistic effect of vacuum flash evaporation and annealing crystallization: This embodiment achieves decoupling of solvent removal and crystallization processes by first performing vacuum flash evaporation followed by thermal annealing. This separation allows each process to be carried out under optimal conditions, avoiding the contradiction of controlling both solvent removal and crystallization kinetics in a single process. Existing methods that commonly involve simultaneous thermal annealing and solvent evaporation cannot independently optimize these two key processes.

[0052] This embodiment not only defines the process steps, but also optimizes the combination of key process parameters through extensive experiments: Matching vacuum level and holding time: This embodiment found that matching a vacuum level <10 Pa with a holding time of 20-40 seconds is crucial for achieving efficient desorption while avoiding film bubbling. Further optimization of the combination of a vacuum level <5 Pa and a holding time of 20-30 seconds achieves the best results.

[0053] Correlation between substrate size and flash evaporation time: This embodiment provides differentiated flash evaporation time parameters (20~40 seconds vs 30~50 seconds) for substrates of different sizes (30×30cm vs 0.6×1.2m) for the first time, solving the problem of inconsistent solvent volume between the edge and center in large-area fabrication. This optimization of the correlation between parameters and substrate size has not been reported in the prior art.

[0054] Synergy between ternary solvent ratio and flash evaporation process: The ternary solvent system in this embodiment must be combined with an optimized vacuum flash evaporation process to achieve the best results. Applying the ternary solvent of this embodiment to a conventional flash evaporation process (e.g., vacuum degree > 20 Pa, holding time > 60 seconds) cannot achieve the same technical effect, which demonstrates the close coupling between solvent composition and process parameters.

[0055] In summary, this embodiment, through the design of the ternary solvent system, the optimization of the step sequence, and the matching of process parameters, forms an organic whole, solving multiple technical problems in the vacuum flash evaporation process of perovskite thin films and resulting in significant technological progress.

[0056] Fourth embodiment of the present invention: This embodiment describes a perovskite thin film prepared by the method described above. The film has a solvent residue of ≤0.3% and a grain size of 500-800 nm.

[0057] Fifth embodiment of the present invention: This embodiment provides a perovskite solar cell whose light-absorbing layer is the perovskite thin film described above. The photoelectric conversion efficiency of the cell is ≥20.1% (effective area ≥0.06m²).

[0058] First experimental example of the present invention: A 30×30cm thin film was prepared using a ternary system (DMF:NMP: 2-methoxyethanol = 7:1:0.5). Step 1: Preparation of ternary mixed solvent Under argon protection, 21 mL of DMF (99.9% purity, 25 ppm water content) and 3 mL of NMP (99.9% purity, 28 ppm water content) were mixed and stirred for 10 minutes; then 1.5 mL of 2-methoxyethanol (99.9% purity, 124℃ boiling point) was added and stirred for another 20 minutes.

[0059] Step 2: Preparation of precursor solution Take FAI (0.95 mmol), MAPBr (0.05 mmol), and PbI2 (1.0 mmol), add 25.5 mL of the above ternary mixed solvent, and stir at 25 °C and 500 rpm for 3 hours to obtain 1.0 mol / L (FAPbI3). 0.95 (MAPbBr3) 0.05 The precursor solution is clear and free of precipitate.

[0060] Step 3: Substrate pretreatment and coating The 30×30cm FTO substrate was ultrasonically cleaned (cleaning agent → deionized water) and UV ozone cleaned for 20 minutes; the slot coating speed was 8mm / s and the liquid injection volume was 250μL to form a uniform wet film.

[0061] Step 4: Vacuum flash evaporation and annealing The vacuum system was set at 10 Pa for 25 seconds; then annealed at 150°C for 25 minutes and cooled to room temperature.

[0062] Results detection is as follows Figures 2-6 As shown: Thin film properties: grain size 650~1000nm (SEM); Surface roughness Ra = 16.3 nm (AFM); Module efficiency: The photoelectric conversion efficiency of the 30×30cm module is 21.23% (Voc=45.V, Isc=0.384mA, FF=0.79).

[0063] Second experimental example of the present invention: A 30×30cm thin film was prepared using a ternary system (DMF:NMP:acetonitrile = 7:1:1). Difference parameters compared to the first experimental example above: The ratio of the ternary solvent is as follows: DMF 21mL, NMP 3mL, acetone 3mL (boiling point 81.6°C, purity 99.9%), water content 35ppm; Flash evaporation conditions: vacuum degree 10 Pa, holding time 25 seconds; The other steps are the same as in the first experimental example described above.

[0064] Results detection is as follows Figures 7-11 As shown: Grain size 500-1000nm (SEM); Perovskite roughness 16.3 nm (AFM); Module efficiency: The photoelectric conversion efficiency of the 30×30cm module is 21.15% (Voc=45.7V, Isc=0.382mA, FF=0.79).

[0065] Comparative examples of the present invention: DMF-NMP binary system (Comparative Example 1) Difference parameters compared to the first experimental example above: Solvent system: DMF:NMP = 6:1 (no low-boiling-point solvents); Flash evaporation conditions: vacuum degree 5Pa, heating stage temperature 100℃, holding time 50 seconds; The other steps are the same as in the first experimental example described above.

[0066] Results detection is as follows Figures 12-16 As shown: Grain size 300-800nm ​​(SEM); Perovskite roughness 23.1 nm (AFM); Module efficiency: The photoelectric conversion efficiency of the 30×30cm module is 21.16% (Voc=46V, Isc=0.382mA, FF=0.8).

[0067] I. Core Performance Comparison and Analysis: 1. Comparison of production efficiency and energy consumption: The ternary solvent system reduces flash evaporation time from 50 seconds to 25 seconds, increasing production efficiency by 100%. This means that in industrial production, output can be doubled in the same amount of time, while the vacuum system operating time is halved, significantly reducing energy consumption.

[0068] 2. Comparison of film quality: First experimental example: grain size range 650-1000nm, surface roughness Ra16.3nm, excellent film uniformity; Second experimental example: grain size range 500-1000nm, surface roughness Ra16.3nm, film uniformity is good; Comparative example: Grain size range 300-800nm, surface roughness 23.1nm, film uniformity is average.

[0069] The ternary system promotes uniform grain growth: the grain size distribution in the first experimental example is more concentrated, indicating that the crystallization process is more controllable.

[0070] Significantly improved surface quality: The roughness of the ternary system is reduced by about 30%, which means: reduced light scattering loss and improved light absorption efficiency; improved electrode contact and reduced interfacial recombination; and improved device stability and reliability.

[0071] 3. Device performance comparison: The photoelectric conversion efficiency of the three groups of experiments is basically the same (about 21.2%), but this just proves the core value of the present invention: while maintaining high efficiency, it greatly improves production efficiency.

[0072] II. Summary of Technical Principles: 1. The "microchannel" effect: In the first experimental example, 2-methoxyethanol (boiling point 124℃) preferentially evaporated under vacuum conditions, forming a gas escape channel, which effectively promoted the desorption of high-boiling-point solvents (DMF boiling point 153℃, NMP boiling point 202℃). This is the key mechanism for achieving rapid flash evaporation in 25 seconds.

[0073] 2. The Importance of Solvent Screening: 2-Methoxyethanol: It has a moderate boiling point and good compatibility with perovskite components, allowing it to evaporate quickly without causing film defects.

[0074] Acetonitrile: It has a lower boiling point (81.6℃) and evaporates faster, but care should be taken to control the amount used to avoid excessively rapid evaporation that could lead to uneven film.

[0075] 3. The scientific basis of the optimized formula: In the first experimental example, the proportion of low-boiling-point solvent was 0.5 / 8.5≈5.9%, which is within the preferred range (0.05:1 to 0.3:1). This ensured the acceleration effect while avoiding film quality problems caused by excessive addition.

[0076] III. Summary of Technological Innovations 1. This invention does not simply replace solvent components, but rather generates a synergistic effect through a ternary system with a specific ratio: Maintain high efficiency (21.23% vs 21.16%). Reduce process time (25 seconds vs. 50 seconds); Improve film quality (roughness 16.3nm vs 23.1nm). The ternary system is not a simple combination, but rather the effect of 1+1+1>3 produced by the components in a specific ratio.

[0077] 2. Overcame technological bias: Current technology generally holds that high-boiling-point solvents such as NMP inevitably lead to long flash evaporation times; there is an inherent contradiction between efficiency and production capacity.

[0078] This invention successfully overcomes this technical bias by introducing a specific low-boiling-point solvent.

[0079] 3. Comprehensive solution to technical problems: Existing technologies can only optimize efficiency or speed in a single aspect, while this invention solves multiple technical problems simultaneously for the first time without significantly increasing costs.

[0080] 4. Experimental data proves that this invention simultaneously meets the three core requirements for the industrialization of perovskite solar cells: High quality: high efficiency and good crystallization; High efficiency: Production cycle reduced by 50%; Low cost: Reduced energy consumption and increased production capacity.

[0081] 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.

[0082] 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.

[0083] 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 perovskite thin film solvent, characterized in that, A ternary mixed solvent consisting of a main solvent, a coordination modifier solvent, and an accelerating desorption agent; The main solvent is N,N-dimethylformamide; The coordination-regulating solvent is N-methylpyrrolidone; The accelerating desorption agent is selected from at least one of 2-methoxyethanol, acetonitrile or isopropanol, and its boiling point range is 80~150℃. The volume ratio of N,N-dimethylformamide to N-methylpyrrolidone is 4:1 to 9:1; The volume ratio of the accelerated desorption agent to the mixture of N,N-dimethylformamide and N-methylpyrrolidone is 0.05:1 to 1:

1.

2. The perovskite thin film solvent as described in claim 1, characterized in that, The volume ratio of N,N-dimethylformamide to N-methylpyrrolidone in the ternary mixed solvent is 6:1 to 8:1; and / or the volume ratio of the accelerated desorption agent to the mixture of N,N-dimethylformamide and N-methylpyrrolidone is 0.05:1 to 0.3:

1.

3. The perovskite thin film solvent as described in claim 1, characterized in that, The water content of the N,N-dimethylformamide and N-methylpyrrolidone is ≤30ppm, and the total water content of the ternary mixed solvent is ≤50ppm.

4. A perovskite precursor solution, characterized in that, The perovskite precursor is dissolved in any of the ternary mixed solvents described in claims 1 to 3 to form a perovskite precursor solution, wherein the perovskite precursor has the general chemical formula ABX3, and the A-site is a monovalent organic cation FA. + MA + or Cs + At least one of them, with the B site being Pb 2+ X is I - ,Br - or Cl - At least one of the following; the concentration of the perovskite precursor solution is 0.8~1.6 mol / L.

5. The perovskite precursor solution as described in claim 4, characterized in that, The perovskite precursor is (FAPbI3). 0.95 (MAPbBr3) 0.05 .

6. A method for preparing a perovskite thin film, characterized in that, Includes the following steps: Step 1, perovskite precursor solution preparation step: Prepare the perovskite precursor solution as described in claim 4 above; Step 2, Substrate Pretreatment: Select FTO / ITO substrates and perform ultrasonic cleaning and UV ozone cleaning; Step 3, Perovskite wet film coating step: The perovskite precursor solution from step 1 is coated onto the pretreated FTO / ITO substrate from step 2 using a slot coating method to form a wet film; wherein, the coating speed is 5~50mm / s. Step 4, Vacuum flash evaporation: Transfer the FTO / ITO substrate coated in step 3 to an environment with a vacuum degree of less than 10 Pa for vacuum flash evaporation, and hold pressure for 20~50 seconds; Step 5, Annealing and Crystallization: Transfer the flash-evaporated FTO / ITO substrate to an annealing furnace and anneal at 100~150℃ for 20~30 min, then allow it to cool naturally to room temperature to obtain a perovskite film.

7. The method for preparing a perovskite thin film as described in claim 6, characterized in that, The processing conditions in step 1 are as follows: under inert gas protection, N,N-dimethylformamide and N-methylpyrrolidone in a volume ratio of 4:1 to 9:1 are mixed and stirred for 8 to 12 minutes, then an accelerating desorption agent is slowly added and stirring is continued for 18 to 22 minutes; at room temperature of 25±2℃ and humidity ≤40%RH, the perovskite precursor is dissolved in a ternary mixed solvent at a stirring speed of 600 to 1000 rpm for 2 to 4 hours to ensure complete dissolution of the perovskite precursor solute.

8. The method for preparing a perovskite thin film as described in claim 6, characterized in that, In step 4, the vacuum level is rapidly reduced to below 10 Pa within the initial 5 to 10 seconds of flash evaporation, and this vacuum level is maintained until the pressure holding ends.

9. A perovskite thin film, characterized in that, Prepared by the method described in any one of claims 6 to 8 above.

10. A perovskite solar cell, characterized in that, Its light-absorbing layer is a perovskite thin film as described in claim 9 above.

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