Synthesis method and application of perovskite microcrystal

Abstract

The invention discloses a synthesis method and application of a perovskite microcrystal, and the synthesis method comprises the following steps: uniformly mixing molten liquid sulfolane with A-site molecules, then adding B-site molecules, and uniformly mixing for reaction to obtain the perovskite microcrystal, the A-site molecule comprises at least one of halogenated methylamine, halogenated formamidine and cesium salt; the B-site molecule comprises lead halide. The method can simplify reaction conditions, reduce the cost of raw materials for synthesis and improve the yield. In addition, no toxic reagent is used in the synthesis process, so that the whole synthesis process is environment-friendly. Meanwhile, sulfolane is used as a solvent system, crystallization of the perovskite crystal can be guided, and the prepared perovskite crystal can prolong a processing window of a large-area perovskite thin film.

Description

Technical Field

[0001] This invention belongs to the field of perovskite preparation technology, specifically relating to a method for synthesizing perovskite microcrystals and its application. Background Technology

[0002] With the development of perovskite solar cell (PSC) technology, the field is steadily progressing towards large-area, large-scale mass production, environmental friendliness, stability, and high efficiency. Among these advancements, achieving stable and large-scale synthesis of perovskite crystals is a key prerequisite for preparing high-quality perovskite precursor solutions and constructing large-area perovskite solar cell modules.

[0003] Currently, the precursor solution for ABX3 perovskite solar cells is mainly prepared via a mixing method, which involves directly mixing and reacting high-purity raw materials (such as 99.999% PbX2 and 99.99% AX). However, this method faces two major challenges: firstly, the use of high-purity raw materials significantly increases production costs; secondly, the synthesis process relies on various toxic or highly toxic solvents, including good solvents such as N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), 2-methoxyethanol (2-ME), N-methylpyrrolidone (NMP), acetonitrile (ACN), and γ-butyrolactone (GBL), as well as undesirable solvents such as diethyl ether (Et2O) and chlorobenzene (CB). These solvents increase operational risks and pose serious challenges to environmental protection, significantly impacting operational safety and environmental friendliness. Furthermore, the preparation of perovskite photovoltaic devices using crystalline precursor solutions also presents a processing window issue—the timing of treatment steps such as anti-solvent treatment, air knife treatment, or vacuum flash evaporation must be precisely controlled during the conversion from the precursor solution to the perovskite thin film. In the preparation of perovskite thin films, there is a narrow "processing window" for the film formation of low-purity or defective crystals. If the processing time is brought forward or delayed, it may interfere with the nucleation and growth process of perovskite crystals, resulting in a loose film structure, increased defects, and difficulty in obtaining dense and uniform high-quality films.

[0004] In summary, current preparation methods suffer from problems such as high raw material costs, complex processes, the use of toxic solvents in the synthesis process, environmental unfriendliness, and the tendency for the synthesized crystals to contain defects. Summary of the Invention

[0005] This invention aims to address at least one of the technical problems existing in the prior art. To this end, this invention proposes a method for synthesizing perovskite microcrystals, which simplifies reaction conditions, reduces raw material costs, and increases yield. Furthermore, since no toxic reagents are used in the synthesis process, the entire process is environmentally friendly. Simultaneously, the use of sulfolane as a solvent system guides the crystallization of perovskite crystals, and the prepared perovskite crystals can extend the processing window of large-area perovskite films.

[0006] The present invention also proposes applications of the above-mentioned synthesis method.

[0007] This invention also proposes a method for preparing a perovskite solar cell module.

[0008] According to a first aspect of the present invention, a method for synthesizing perovskite microcrystals is provided, the method comprising the following steps: Liquid sulfolane is mixed with A-site molecules, and then B-site molecules are added and mixed to react, thus obtaining perovskite microcrystals. The A-site molecule includes at least one of methylamine halide, formamidine halide, and cesium salt; The B-site molecule includes lead halide.

[0009] The synthesis method provided by this invention uses sulfolane as the reaction medium and regulates the perovskite crystallization process through its unique solvation effect, which has the following advantages: (1) Simplified process: The reaction conditions are mild and no complex equipment is required; (2) Economical and efficient: Raw material costs are reduced by more than 91% (taking FAPbI3 as an example), and the yield exceeds 85%; (3) Environmentally friendly: All reaction solvents are green and environmentally friendly solvents; (4) Film formation optimization: The coordination effect of sulfolane can induce the directional crystallization of perovskite. The prepared perovskite crystals can be used in perovskite precursor solutions to extend the processing window of large-area perovskite films and significantly improve the uniformity and coverage of the films.

[0010] The chemical reaction equations that occur during the synthesis process are as follows: AX + PbX2→ APbX3↓(I); AX+ APbX3 2A + +Pb + + 4X (II).

[0011] Reaction (I) is the reaction that forms a perovskite crystal precipitate. During the initial feeding stage, AX and PbX2 enter the sulfolane system and dissociate to form A. + and X Ions, at this time the reaction entropy Δ r S < reaction equilibrium constant The reaction shifts to the forward direction, and perovskite crystals gradually precipitate, forming a sulfolane suspension. The equilibrium constant for reaction (II) is... A dynamic equilibrium is formed with reaction (I). In the initial stage of feeding, reaction (I) dominates, and perovskite crystals separate from the reaction system by precipitation.

[0012] In some embodiments of the present invention, the A-site molecule includes at least one of methylamine iodide, methylamine bromide, formamidinium hydroiodate, formamidinium bromide, cesium iodide, and cesium bromide.

[0013] In some embodiments of the present invention, the molecule at the A site is selected from at least one of methylamine iodide (MAI, CAS: 14965-49-2), formamidinium hydroiodate (FAI, CAS: 879643-71-7) and cesium iodide (CsI, CAS: 7789-17-5).

[0014] In some embodiments of the present invention, the B-site molecule includes at least one of lead iodide (PbI2, CAS: 10101-63-0), lead bromide (PbBr2, CAS: 10031-22-8), and lead chloride (PbCl2, CAS: 7758-95-4).

[0015] In some embodiments of the present invention, the molar ratio of sulfolane to the A-site molecule is (2~6):1.

[0016] In some embodiments of the present invention, the molar ratio of the A-site molecule to the B-site molecule is (1.1~2):1.

[0017] In some embodiments of the present invention, the molar ratio of the A-site molecule to the B-site molecule is (1.1~1.8):1.

[0018] Therefore, the excess of A-site molecules ensures that the more expensive B-site molecules react fully, improving the economics of the synthesis method; it avoids the low yield and side reactions caused by stoichiometric mismatch in the direct mixing method, and also ensures reduced perovskite dissolution.

[0019] In some embodiments of the present invention, the mixing of sulfolane with the A-site molecule and the reaction after the addition of the B-site molecule are both carried out under stirring conditions of 32°C to 38°C.

[0020] In some embodiments of the present invention, the stirring speed is 300~500 rpm.

[0021] In some embodiments of the present invention, the stirring speed is 350~450 rpm.

[0022] In some embodiments of the present invention, the reaction time is 16-24 h.

[0023] In some embodiments of the present invention, the reaction time is 16-20 h.

[0024] In some embodiments of the present invention, the synthesis method further includes purification after the reaction is completed, the purification including sequential solid-liquid separation, washing and drying.

[0025] In some embodiments of the present invention, the solid-liquid separation includes at least one of conventional filtration, pressure filtration, and vacuum filtration.

[0026] In some embodiments of the present invention, the washing solvent used for washing includes ethyl acetate.

[0027] In some embodiments of the present invention, the amount of the washing solvent is at least 100 times that of the perovskite microcrystals.

[0028] In some embodiments of the present invention, the drying method is vacuum drying.

[0029] In some embodiments of the present invention, the temperature of the vacuum drying is 30°C to 100°C.

[0030] In some embodiments of the present invention, the vacuum drying temperature is 40°C.

[0031] In some embodiments of the present invention, the drying time is 24 to 48 hours.

[0032] In some embodiments of the present invention, the perovskite obtained by the synthesis method is preserved by isolating it from air and shielding it from light. This avoids the influence of air and light on the properties of the perovskite. For example, it avoids phase transitions caused by components in the air.

[0033] In some embodiments of the invention, the air-isolation method includes atmosphere protection, such as placing the device in a glove box filled with nitrogen or inert gas.

[0034] In some embodiments of the present invention, the perovskite obtained by the synthesis method exists in the form of powder.

[0035] In some embodiments of the present invention, the perovskite obtained by the synthesis method is in a crystalline state.

[0036] According to a second aspect of the present invention, the application of the method for synthesizing perovskite microcrystals described in the first aspect of the present invention in the fabrication of optoelectronic devices is proposed.

[0037] In some embodiments of the present invention, the optoelectronic device includes at least one of perovskite solar cells, photodetectors, light-emitting diodes, and radiation detectors.

[0038] According to a third aspect of the present invention, a method for fabricating a perovskite solar cell module is provided. A perovskite precursor solution is coated onto a conductive glass coated with a hole transport layer, and after drying, a perovskite layer is formed; then an electron transport layer and a metal electrode are sequentially deposited on the surface of the perovskite layer to obtain a perovskite solar cell module; the perovskite precursor solution contains perovskite microcrystals obtained by the synthesis method described in the first aspect of the present invention.

[0039] In some embodiments of the present invention, the solvent of the perovskite precursor solution includes DMF and NMP.

[0040] In some embodiments of the present invention, the volume ratio of DMF to NMP is (5~7):1.

[0041] In some embodiments of the present invention, the drying method includes at least one of air knife blowing, microwave drying, and vacuum flash evaporation.

[0042] In some embodiments of the present invention, the perovskite solar cell module is further divided into sub-cells by dicing; the dicing method includes at least one of laser etching and mechanical dicing.

[0043] The present invention has at least the following beneficial effects: 1) This invention achieves a one-step synthesis of perovskite crystals by controlling the amount of A-site molecules fed. Excess A-site molecules can completely react with B-site molecules, removing PbX2 impurities from the perovskite. By controlling the amount of A-site molecules fed, high-purity perovskite crystals can be synthesized from low-grade raw materials, achieving a high yield while reducing costs.

[0044] 2) Using sulfolane as the reaction solvent eliminates the need for toxic reagents in the synthesis process, significantly improving its environmental friendliness. This improvement not only simplifies the synthesis process and reduces its complexity, but also substantially reduces the cost of post-processing and protection against toxic substances during production. This provides strong support for the large-scale synthesis of perovskite crystals and promotes their industrialization in practical applications.

[0045] 3) Sulfolane (TMSO2) is an aprotic polar solvent with a high boiling point (285℃), high dielectric constant (approximately 42.5), and excellent thermal stability. Its strongly polar sulfone group (-SO2) in its molecular structure can react with Pb² in perovskite precursors. + The ions undergo strong Lewis acid-base coordination to form stable complex intermediates. This coordination effect plays a crucial role in both the synthesis and film formation stages. During the crystal synthesis stage: This coordination effect regulates the nucleation and growth kinetics of perovskite crystals, making the crystallization process more orderly and effectively suppressing the generation of lattice defects, thereby obtaining perovskite microcrystalline powder with high crystallinity, few impurities, and complete structure.

[0046] In the thin film preparation stage: When using the perovskite crystals prepared by this method to prepare the precursor solution, the coordination effect of sulfolane is sustained. The complex structure formed in solution significantly reduces the solvent evaporation rate and the initial crystallization rate of the perovskite, extending the processable time window of the wet film after blade coating (from approximately 5 seconds in the conventional method to over 10 seconds). This provides ample operating time for large-area, continuous preparation, allowing for more precise and uniform film treatment (such as air knife sweeping), effectively avoiding problems such as uneven film formation, porosity, and phase separation caused by improper processing timing. Attached Figure Description

[0047] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a comparison of the solubility of perovskite microcrystals FAPbI3 in TMSO2 and DMF in this invention. Figure 2 This is a schematic diagram of the large-area perovskite device structure in Embodiment 4 of the present invention; Figure 3 The XRD pattern of the perovskite obtained in Example 1 of the experimental examples of this invention; Figure 4 This is a SEM image of the perovskite obtained in Example 1 of the experimental examples of the present invention; wherein the scale bar is 200 μm; Figure 5 The XRD pattern of the perovskite obtained in Example 2 of the experimental examples of this invention; Figure 6 This is a SEM image of the perovskite obtained in Example 2 of the experimental examples of the present invention; wherein the scale bar is 50 μm; Figure 7 The XRD pattern of the perovskite obtained in Example 3 of the experimental examples of this invention; Figure 8 This is a SEM image of the perovskite obtained in Example 3 of the experimental examples of the present invention; wherein the scale bar is 500 μm; Figure 9 The image shows a SEM image of the perovskite obtained in Comparative Example 1 of the present invention; the scale bar is 200 μm. Figure 10 These are in-situ optical microscope crystallography images of Example 4 and Comparative Example 2 in the experimental examples of this invention; Figure 11 This is an IV curve diagram of the perovskite large-area modules prepared in Example 4, Comparative Example 2 and Comparative Example 3 of the present invention, tested under simulated sunlight. Detailed Implementation

[0048] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0049] Unless otherwise specified, the experimental methods used in the embodiments are conventional methods; the materials and reagents used are commercially available unless otherwise specified. Unless otherwise specified, the same parameter values ​​are used in all embodiments. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0050] This invention presents a method for synthesizing perovskite crystals using the green solvent sulfolane as the solvent system. This method simplifies reaction conditions, reduces raw material costs, and increases yield. Furthermore, since no toxic reagents are used in the synthesis process, the entire process is environmentally friendly. Simultaneously, using sulfolane as the solvent system guides the crystallization of perovskite crystals, extending the processing window of large-area perovskite films.

[0051] Sulfolane (TMSO2) is an aprotic polar solvent with a high boiling point (285℃), high dielectric constant (approximately 42.5), and excellent thermal stability. Its strongly polar sulfone group (-SO2) in its molecular structure can react with Pb in perovskite precursors. 2+ The ions undergo strong Lewis acid-base coordination to form stable complex intermediates. This coordination effect plays a crucial role in both the synthesis and film formation stages. During the crystal synthesis stage: This coordination effect regulates the nucleation and growth kinetics of perovskite crystals, making the crystallization process more orderly and effectively suppressing the generation of lattice defects, thereby obtaining perovskite microcrystalline powder with high crystallinity, few impurities, and complete structure.

[0052] In the thin film preparation stage: When using the perovskite crystals prepared by this method to prepare the precursor solution, the coordination effect of sulfolane is sustained. The complex structure formed in solution significantly reduces the solvent evaporation rate and the initial crystallization rate of the perovskite, extending the processable time window of the wet film after blade coating (from approximately 5 seconds in the conventional method to over 10 seconds). This provides ample operating time for large-area, continuous preparation, allowing for more precise and uniform film treatment (such as air knife sweeping), effectively avoiding problems such as uneven film formation, porosity, and phase separation caused by improper processing timing.

[0053] Conventional knowledge in the art tends to favor solvents with high solubility for the reactants (such as DMF) to ensure a complete reaction. However, this invention demonstrates experimentally that sulfolane has a significantly lower solubility for perovskite crystals than the aforementioned conventional solvents. Figure 1 As shown, 10 mg of perovskite microcrystals FAPbI3 were placed in two separate reagent bottles, and 0.5 mL of sulfolane (TMSO2) and DMF solution were added to each. The bottles were then tightly capped and subjected to vigorous shaking on a vortex stirrer for 1 min. The results showed that a large amount of FAPbI3 perovskite microcrystals remained at the bottom of the bottle containing TMSO2, while all the FAPbI3 perovskite microcrystals in the bottle containing DMF dissolved. This invention utilizes the "weak solubility" of sulfolane and its unique coordination ability to cleverly control the crystallization kinetics of perovskite, thereby achieving efficient and green synthesis of high-quality perovskite microcrystals under mild conditions.

[0054] Unless otherwise specified, the following embodiments are as follows: FAI is synthesized using HI and FAAC; CsI ​​was synthesized using HI and CsAc; MAI is synthesized using HI and MA; HI was purchased from Maclean's reagent and was a 47 wt% aqueous solution. ρ = 1.701 g / mL; FAAc was purchased from Maclean's reagents and had a purity of 99 wt%. CsAc was purchased from Maclean's reagents and had a purity of 99 wt%. MA was purchased from Aladdin and was a 30-33 wt% ethanol solution. ρ = 0.785 g / mL; PbI2 was purchased from Aladdin, with a purity of 99.5 wt%. Sulfolane was purchased from Maclean's reagent, with a purity of 99.9 wt%. ρ = 1.26 g / mL; ACN was purchased from Shanghai Lingfeng Chemical Reagent Co., Ltd., with a purity of 99.8 wt%. ρ = 0.786 g / mL; The ITO conductive glass was purchased from Liaoning Youxuan New Energy Technology Co., Ltd., with a conductivity of 7~9 Ω / sq. IPA was purchased from Beijing Bailingwei Technology Co., Ltd., with a purity of 99.5 wt%. ρ = 0.786 g / mL; C 60 Purchased from Xi'an Juhui Optoelectronics Technology Co., Ltd., purity 99.9%; Cu was purchased from Zhongnuo New Materials Technology Co., Ltd., with a purity of 99.999%. DMF was purchased from Beijing Bailingwei Technology Co., Ltd., with a purity of 99.8%. NMP was purchased from Beijing Bailingwei Technology Co., Ltd., with a purity of 99.5%. CsI ​​was purchased from Liaoning Youxuan New Energy Technology Co., Ltd., with a purity of 99.99%. The PbCl2 was purchased from Liaoning Youxuan New Energy Technology Co., Ltd., with a purity of 99.99%.

[0055] Example 1 This embodiment synthesizes a perovskite microcrystalline powder. The specific synthesis method is as follows: S1. First, melt sulfolane in a water bath at 35°C. Add 13 mmol of sulfolane and 3.6 mmol of FAI to a 25 mL flask, set the water bath to 35°C, and stir with a magnetic stirrer at 400 rpm until the FAI is completely dissolved. Use a paper trough to slowly add 2 mmol of PbI2 to the reaction mixture and continue the reaction for 18 h.

[0056] S2. Using a dropper, add the reaction product obtained in step S1 into a sintered sand funnel and filter rapidly at room temperature using a PTFE filter membrane with a pore size of 0.2 μm. Next, add 20 mL of ethyl acetate around the funnel wall to elute the remaining solvent. Once the pressure gauge reading gradually decreases, remove the filtration tube. Transfer the resulting bright yellow powder to a 20 mL sample bottle, dry in a vacuum drying oven at 40°C for 24 h, and then transfer to a vacuum glove box for storage to obtain perovskite microcrystalline FAPbI3.

[0057] Example 2 This embodiment synthesizes a perovskite microcrystalline powder. The specific synthesis method is as follows: S1. First, melt sulfolane in a water bath at 35°C. Add 13 mmol of sulfolane and 5.8 mmol of MAI to a 25 mL flask, set the water bath to 35°C, and stir with a magnetic stirrer at 400 rpm until the MAI is completely dissolved. Use a paper trough to slowly add 3.9 mmol of PbI2 to the reaction mixture and continue the reaction for 18 h.

[0058] S2. Using a dropper, add the reaction product obtained in step S1 into a sintered sand funnel and filter rapidly at room temperature using a PTFE filter membrane with a pore size of 0.2 μm. Next, add 20 mL of ethyl acetate around the funnel wall to elute the remaining solvent. Once the pressure gauge reading gradually decreases, remove the filtration tube. Transfer the resulting bright yellow powder to a 20 mL sample bottle, dry in a vacuum drying oven at 40°C for 24 h, and then transfer to a vacuum glove box for storage to obtain perovskite microcrystalline MAPbI3.

[0059] Example 3 This embodiment synthesizes a perovskite microcrystalline powder. The specific synthesis method is as follows: S1. First, melt sulfolane in a water bath at 35°C. Add 26 mmol of sulfolane and 4.5 mmol of CsI to a 25 mL flask, set the water bath to 35°C, and stir with a magnetic stirrer at 400 rpm until all CsI is dissolved. Use a paper trough to slowly add 4 mmol of PbI2 to the reaction mixture and continue the reaction for 18 h.

[0060] S2. Using a dropper, add the reaction product obtained in step S1 into a sintered sand funnel and filter rapidly at room temperature using a PTFE filter membrane with a pore size of 0.2 μm. Next, add 20 mL of ethyl acetate around the funnel wall to elute the remaining solvent. Once the pressure gauge reading gradually decreases, remove the filtration tube. Transfer the resulting bright yellow powder to a 20 mL sample bottle, dry in a vacuum drying oven at 40°C for 24 h, and then transfer to a vacuum glove box for storage to obtain perovskite microcrystalline CsPbI3.

[0061] Example 4 This embodiment prepares a large-area perovskite solar cell module based on the perovskite microcrystalline FAPbI3 provided in Example 1. The module structure is as follows: Figure 2 As shown, this large-area module includes a transparent electrode A, a hole transport layer B, a perovskite active layer C, an electron transport layer D, and a metal electrode E. The perovskite active layer C is prepared by applying a perovskite precursor solution using a doctor blade. The specific preparation method is as follows: A1. Preparation of perovskite precursor solution: PbCl2 (0.3 mmol), CsI (0.7 mmol), PbI2 (0.7 mmol) and FAPbI3 (1.2 mmol) perovskite microcrystals prepared in Example 1 were simultaneously dissolved in a mixed solvent consisting of 1 mL DMF and 0.15 mL NMP. The mixture was stirred for 2.5 hours (2 to 3 hours is also acceptable) to ensure complete dissolution, thus obtaining perovskite precursor solution 1.

[0062] A2. Preparation of a large-area perovskite active layer: Clean a 5×5 cm ITO conductive glass substrate. Dissolve 4PADCB in IPA to prepare a solution with a mass concentration of 1 g / mL. Take 20 μL and drop it onto the ITO conductive glass substrate, then spin-coat at 5000 r / min for 20 s. After spin-coating, anneal the sample on a hot plate at 130 ℃. Wipe the doctor blade clean and press it onto the ITO conductive glass substrate with the hole transport layer, adjusting the slit width to 0.4±0.05 mm. Use a pipette to drop 0.2±0.05 μL of perovskite precursor solution 1 onto the hole transport layer, and uniformly coat the perovskite precursor solution 1 at a speed of 3±0.5 mm / s. After coating, a wet perovskite film is left on the substrate. Use a nitrogen air knife at 0.4 bar pressure at a speed of 4±0.5 mm / s to blow away the wet perovskite film, forming a perovskite layer. The dried perovskite was annealed at 150℃ for 10±1 min to obtain an α-phase perovskite active layer with a thickness of about 400 nm.

[0063] A3. Fabrication of large-area modules: A 4.5 nm thick electron transport layer C is deposited on the perovskite active layer at a speed of 0.04 nm / s (0.03~0.05 nm / s is acceptable). 60 Subsequently, a P2 laser was used to scribing the perovskite into 6 perovskite cell blocks connected in series. Finally, a 10 nm metal electrode Cu was deposited at a speed of 10 nm / s, and a P3 laser was used to separate the individual sub-cells, ultimately obtaining a large-area perovskite solar cell module.

[0064] Comparative Example 1 This comparative example uses ACN to synthesize perovskite powder FAPbI3. The specific preparation method is as follows: S1. Add 4 mmol FAI to a 25 mL flask, add 20 mL ACN, maintain the reaction temperature at 25℃, set the magnetic stirrer speed to 400 rpm, and stir until FAI is completely dissolved. Using a paper trough, slowly add 2 mmol PbI2 to the reaction mixture and continue the reaction for 18 h.

[0065] S2. After the reaction is complete, lower the temperature of the reaction system until crystals precipitate. Remove the supernatant after the reaction, and wash the crystals three times with ether for 25 min each time. Finally, transfer the yellow FAPbI3 perovskite crystal powder to a vacuum drying oven and dry at room temperature (about 40°C) for 24 h, then transfer it to a vacuum glove box for storage.

[0066] Comparative Example 2 This comparative example uses the perovskite microcrystalline FAPbI3 provided in Comparative Example 1 to prepare a large-area perovskite solar cell module. The specific preparation method is as follows: Preparation of perovskite precursor solution: PbCl2 (0.3 mmol), CsI (0.7 mmol), PbI2 (0.7 mmol) and FAPbI3 (1.2 mmol) perovskite microcrystals prepared in Comparative Example 1 were simultaneously dissolved in a mixed solvent consisting of 1 mL DMF and 0.2 mL NMP. The mixture was stirred for 2-3 hours until it was completely dissolved, thus obtaining perovskite precursor solution 2.

[0067] Perovskite large-area modules were prepared using perovskite precursor solution 2, and the preparation method was the same as steps A2 and A3 in Example 4.

[0068] Comparative Example 3 This comparative example yields a large-area perovskite solar cell module, and the specific fabrication method is as follows: Preparation of perovskite precursor solution: PbCl2 (0.3 mmol), CsI (0.7 mmol), PbI2 (0.9 mmol) and FAI (1.2 mmol) were simultaneously dissolved in a mixed solvent consisting of 1 mL DMF and 0.2 mL NMP. The mixture was stirred for 2-3 hours until it was completely dissolved, thus obtaining perovskite precursor solution 3.

[0069] Perovskite large-area modules were prepared using perovskite precursor solution 3, and the preparation method was the same as steps A2 and A3 in Example 4.

[0070] The raw material ratios and product information for Examples 1-3 and Comparative Example 1 are shown in Table 1.

[0071] Table 1. Raw materials and products prepared in Examples 1-3 and Comparative Example 1

[0072] Test case This experiment tested the properties of the perovskite microcrystals obtained in Examples 1-3 and Comparative Example 1. The characteristics of each implementation method are summarized in Table 2.

[0073] Table 2. Reaction parameters and product properties of Examples 1-3 and Comparative Example 1

[0074] In Table 2, the yield refers to the ratio between the actual mass of the perovskite crystals obtained and the theoretically expected mass of the perovskite crystals (i.e., the mass of perovskite assuming at least one reactant has completely reacted and no side reactions occur). According to the data in Table 2, this invention improves the final yield by using sulfolane to synthesize perovskite crystals by adjusting the synthesis method.

[0075] In Table 2, the crystal system and powder quality of the microcrystals were determined by a combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. The XRD pattern and SEM image of the perovskite microcrystalline powder provided in Example 1 are shown below. Figure 3 and Figure 4 As shown; the XRD pattern and SEM image of the perovskite microcrystalline powder provided in Example 2 are shown below. Figure 5 and Figure 6 As shown; the XRD pattern and SEM image of the perovskite microcrystalline powder provided in Example 3 are shown below. Figure 7 and Figure 8 As shown; the SEM image of the perovskite microcrystalline powder obtained in Comparative Example 1 is shown below. Figure 9 As shown.

[0076] This experimental example also used in-situ optical microscopy to record the crystallization process of Example 4 and Comparative Example 2 during the perovskite precursor solution coating and crystallization process. The results are as follows: Figure 10 As shown.

[0077] Depend on Figure 10 It can be seen that Example 4 has a processing time window of approximately 10 seconds from the completion of the coating process to the crystallization of the perovskite, while the comparative example has a processing time window of less than 5 seconds. If no post-processing is performed after the time window has expired, the perovskite film will begin to crystallize randomly. Therefore, the precursor solution for perovskite microcrystal preparation prepared by this invention has the function of significantly extending the processing time window for perovskite preparation compared with the prior art.

[0078] This experimental example tests the performance of the perovskite large-area solar cell modules prepared in Example 4 and Comparative Examples 2-3 under simulated sunlight conditions. The device performance was characterized using a Keithley 2400 source meter and an Enlitech SS-F7-3A solar simulator, which provides 100 mW / cm². 2 The calibration was performed under simulated AM 1.5G illumination using a NIST-certified monocrystalline silicon solar cell (Newport 532 ISO1599). JV curves were obtained through forward scans (-0.1 V to 8 V) and reverse scans (8 V to -0.1 V) at a scan rate of 0.02 V / s and a voltage step size of 20 mV. The results are as follows... Figure 11 As shown.

[0079] Figure 11 IV curves are obtained for performance testing of the perovskite modules prepared in Example 4, Comparative Example 2, and Comparative Example 3 under simulated sunlight, wherein the perovskite devices prepared using the perovskite crystal synthesized from sulfolane described in Example 4 as the precursor are subjected to voltage-on-load testing. V OCThe voltage is 7.215 V, the fill factor (FF) is 77.76%, the power conversion efficiency (PCE) is 22.31%, and the short-circuit current is... I SC It has a voltage of 47.72 mA and an effective area of ​​12.00 cm². 2 Its photoelectric properties are significantly better than those of the two comparative examples.

[0080] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for synthesizing perovskite microcrystals, characterized by, The synthesis method comprises the following steps: mixing liquid sulfolane with A-site molecules, and then mixing and reacting with B-site molecules to obtain perovskite microcrystals; The A-site molecules comprise at least one of methylamine halide, formamidine halide and cesium salt; The B-site molecules comprise lead halide.

2. The method of claim 1, wherein the perovskite microcrystal is synthesized by the following steps of: The A-site molecules comprise at least one of methylamine iodide, methylamine bromide, formamidine hydroiodide, formamidine bromide, cesium iodide and cesium bromide. ​ 3. The method of claim 1, wherein the perovskite microcrystal is synthesized by a method comprising: The B-site molecules comprise at least one of lead iodide, lead bromide and lead chloride. ​ 4. The method of claim 1, wherein the perovskite microcrystal is synthesized by a method comprising: The molar ratio of sulfolane to A-site molecules ranges from 2 to 6:

1.

5. The method for synthesizing perovskite microcrystals according to claim 1, characterized in that, The molar ratio of A-site molecules to B-site molecules ranges from 1.1 to 2:

1.

6. The method of claim 1, wherein the perovskite microcrystal is synthesized by a method comprising: The mixing of sulfolane and A-site molecules and the reaction after adding B-site molecules are both carried out under stirring at 32-38℃. Preferably, the stirring speed is 300-500 rpm.

7. The method for synthesizing perovskite microcrystals according to claim 1, characterized in that, The reaction time is 16-24 h.

8. Use of the synthesis method of perovskite microcrystals in any one of claims 1-7 in the preparation of optoelectronic devices.

9. Use according to claim 8, characterized in that, The optoelectronic devices comprise at least one of perovskite solar cells, photodetectors, light-emitting diodes and radiation detection devices.

10. A method of manufacturing a perovskite solar cell module, characterized by, The preparation method comprises the following steps: coating a perovskite precursor solution on conductive glass coated with a hole transport layer, drying to form a perovskite layer, and then sequentially evaporating an electron transport layer and a metal electrode on the surface of the perovskite layer to obtain a perovskite solar cell module; the perovskite precursor solution contains perovskite microcrystals prepared by the synthesis method in any one of claims 1-7.

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