Additive-assisted aqueous synthesis of multinary cationic perovskites δ-fa x M 1-x Pbil3 solid solutions and methods

Abstract

The application discloses additive-assisted aqueous synthesis of multi-cation perovskite delta-FA x M 1‑x PbI3 solid solution and method, belong to organic-inorganic hybrid perovskite raw material synthesis field.Its chemical formula is FA x M 1‑x PbI3 (0≤x≤1), wherein, FA is formamidinium cation, M is methylamine, Rb + , Cs + Various types of organic-inorganic cations, additives are 2,3,5,6-tetrafluoro-p-phenylenedicyanide, aqueous environment is provided by hydroiodic acid aqueous solution.The application effectively inhibits the damage of water to perovskite structure through the ingenious selection of additives, controls the occupation and distribution of different cations in the crystal structure, and successfully solves the technical problems of unstable product, impure phase, uneven cation distribution and the like in aqueous synthesis.The method has the advantages of simple process, green environmental protection, low cost, easy to scale production and the like, and the prepared solid solution is conducive to realizing low-cost application of the whole perovskite market.

Description

Technical Field

[0001] This invention belongs to the field of perovskite photovoltaic technology, specifically relating to an additive-assisted aqueous phase synthesis of multi-component cationic perovskite δ-FA. x M 1-x PbI3 solid solution and method. Background Technology

[0002] FAPbI3, as a perovskite material, possesses excellent photoelectric properties, including high absorption coefficient, long carrier lifetime, and high charge mobility. These properties make FAPbI3 a promising candidate for applications in the photovoltaic field, significantly improving the photoelectric conversion efficiency of solar cells. In-depth research into the fabrication process, crystal structure, photoelectric properties, and influencing factors of FAPbI3 can drive continuous progress in photovoltaic technology and provide strong support for the development of efficient, low-cost, and long-lifespan photovoltaic devices.

[0003] Currently, FAPbI3 perovskite materials are mostly used to prepare thin films for solar cells. The preparation methods are as follows: (1) Formamidinium hydroiodide and lead iodide are directly dissolved in high-boiling-point organic solvents (N,N-dimethylformamide, dimethyl sulfoxide, etc.), and then the solution is spin-coated onto a certain substrate. After heat treatment, α-FAPbI3 perovskite is formed, and FAPbI3 perovskite thin film is prepared; (2) α-FAPbI3 crystal powder is dissolved in high-boiling-point solvents (N,N-dimethylformamide, dimethyl sulfoxide), and then spin-coated and annealed to obtain perovskite thin film.

[0004] For method (1), since the reactants cannot be completely converted into FAPbI3, the residual FAI or PbI2 and the non-stoichiometric weighing easily lead to a large number of impurities and defects, which is not conducive to improving the quality of perovskite films and device performance. In method (2), since α-FAPbI3 is prone to phase transition at room temperature, the phase purity is not high, which is also not conducive to improving device performance.

[0005] Furthermore, the use of high-boiling-point solvents in the synthesis of α-FAPbI3 crystals increases energy consumption costs; moreover, the preparation of high-purity FAPbI3 crystals requires the synthesis of high-quality single crystals, and the preparation of FAPbI3 single crystal materials often requires a growth cycle of 1 to 2 weeks or even longer, which is not conducive to industrial application and promotion. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide an additive-assisted aqueous phase synthesis method for multi-component cationic perovskite δ-FA. x M 1-x A method for PbI3 solid solution is proposed to address the problems of high energy consumption, high toxicity, and product defects in existing technologies.

[0007] To achieve the above objectives, the present invention employs the following technical solution: An additive-assisted aqueous phase synthesis of multi-component cationic perovskite δ-FA x M 1-x The method for PbI3 solid solution includes the following steps: S1, Pb(Ac)2·3H2O is dissolved in a diluted aqueous solution of hydroiodic acid and stirred to form PbI2; S2, formamidine acetate, iodoform salt, and 2,3,5,6-tetrafluoroterephthalonitrile are added, and the reaction is stirred continuously to generate δ-FA. x M 1-x PbI3 mixture; S3, perform solid-liquid separation on the reaction solution, and wash the solid product with an antisolvent; S4, the washed solid product was dried under vacuum to obtain δ-FA. x M 1-x PbI3 (0≤x≤1) solid solution.

[0008] A further improvement of the present invention is that: Preferably, in S1, the stirring temperature is 20-50℃.

[0009] Preferably, the concentration of the diluted hydroiodic acid aqueous solution is 30%-45%, and the molar ratio of hydroiodic acid to Pb(Ac)2·3H2O in the diluted hydroiodic acid solution is 6:1.

[0010] Preferably, in S2, the molar ratio of Pb(Ac)2·3H2O to formamidine acetate is 1:(1.2-2).

[0011] Preferably, in S2, the molar amount of the iodo-based ion salt added is 1%-100% of the molar amount of Pb(Ac)2·3H2O.

[0012] Preferably, in S2, the amount of 2,3,5,6-tetrafluoroterephthalonitrile added is 0.5%-5% of the molar amount of Pb(Ac)2·3H2O.

[0013] Preferably, in S2, the reaction temperature is 20-60°C. C, the reaction time is 1-3 days.

[0014] Preferably, in S2, 1-2 mL of 55-57% hydroiodic acid solution is added every 4-8 hours during the reaction to maintain the acidity of the reaction solution.

[0015] Preferably, in S3, the antisolvent is ethyl acetate or acetonitrile.

[0016] An additive-assisted aqueous synthesis of multi-component cationic perovskite δ-FA obtained by any one of the methods described above. x M 1-x PbI3 solid solution, the δ-FA x M 1-x The surface of the perovskite crystal in the PbI3 solid solution is adsorbed with 2,3,5,6-tetrafluoroterephthalonitrile.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses an additive-assisted aqueous phase synthesis method for multi-component cationic perovskite δ-FA. x M 1-x The method using PbI3 solid solution involves A-site modulation, which can effectively improve the crystal structure and photoelectric properties of perovskite, thus affecting device performance. However, since δ-FAPbI3 is a one-dimensional structure at room temperature, its crystal bond angle variance increases sharply, the Pb-I octahedron is highly distorted, and the stability of the original three-dimensional structure is destroyed, resulting in a dimensionality reduction phenomenon and the loss of the excellent charge transport properties of the high-dimensional structure. By modulating the A-site composition and introducing Cs... + Rb + Organic and inorganic cations can react with FA + By combining these methods, the octahedral distortion of δ-FAPbI3 can be controlled, thereby improving its charge transport performance and ultimately enhancing the device efficiency of perovskite solar cells. Furthermore, A-site ion regulation of δ-FAPbI3 can effectively shorten the interplanar spacing, reduce the tolerance factor, and improve material stability. In the preparation of the solid solution described in this invention, the introduction of additives can effectively reduce the crystallization rate through the interaction of the strongly coordinating cyano group with lead ions, guiding the crystal to grow in a more regular direction with fewer defects. The added 2,3,5,6-tetrafluoroterephthalonitrile, due to the presence of four fluorine atoms on the benzene ring, constitutes a highly fluorinated hydrophobic surface. When molecules are anchored to the perovskite crystal surface through the cyano group, these fluorine atoms act like a "fluorinated umbrella," effectively blocking the intrusion of water molecules. Therefore, the introduction of additives assists in the aqueous synthesis of multi-component cationic perovskite δ-FAPbI3. x M 1-x PbI3 solid solution growth exhibits higher stability and superior device performance. Therefore, exploring suitable preparation methods for δ-FAPbI3-type perovskite solid solutions is a crucial step in promoting the development of the perovskite solar cell industry.

[0018] This method has the advantages of being green and environmentally friendly, having controllable components, high yield, and low cost. This invention uses hydroiodic acid aqueous solution, a non-organic solvent with less impact on the human body, and inexpensive materials such as Pb(Ac)₂·3H₂O and FAAc as initial raw materials, processed at low temperatures (20-60°C). Method C) of preparation and synthesis offers a cost advantage compared to the FAI+PbI2 method. Furthermore, by introducing additives and regulating the A-site organic and inorganic cations, the operating performance and stability of the device can be significantly improved. Therefore, this invention has significant advantages in five aspects: reaction environment (aqueous phase and low temperature), raw material acquisition, yield, cost, and device performance, which is beneficial to the further development of the perovskite photovoltaic industry. Attached Figure Description

[0019] Figure 1 This is a molecular structure diagram of the additive 2,3,5,6-tetrafluoroterephthalonitrile used in an example of the present invention.

[0020] Figure 2 In this invention, additives are used to assist in the aqueous phase synthesis of multi-component cationic perovskite δ-FA. x M 1-x Flowchart of PbI3 solid solution preparation.

[0021] Figure 3 The X-ray diffraction patterns are shown in Example 1 of this invention before and after the addition-assisted aqueous synthesis of perovskite δ-FAPbI3 solid solution.

[0022] Figure 4 This is a small-angle X-ray diffraction pattern before and after the addition-assisted aqueous synthesis of perovskite δ-FAPbI3 solid solution in Example 1 of the present invention.

[0023] Figure 5 This invention provides an example of additive-assisted aqueous phase synthesis of multi-component cationic perovskite δ-FA. x MA 1-x X-ray diffraction patterns of PbI3 solid solution before and after solidification.

[0024] Figure 6 This invention provides an example of additive-assisted aqueous phase synthesis of multi-component cationic perovskite δ-FA. x MA 1-x Small-angle X-ray diffraction patterns of PbI3 solid solution before and after.

[0025] Figure 7 This invention provides an example of additive-assisted aqueous phase synthesis of multi-component cationic perovskite δ-FA. x Cs 1-x Field scanning electron microstructure images of PbI3 solid solution before and after solidification. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings: To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0027] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0028] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0029] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0030] The first aspect of this invention discloses an additive-assisted aqueous phase synthesis method for multi-component cationic perovskite δ-FA. x M 1- x For the method of PbI3 solid solution, see Figure 1 It includes the following steps: Step 1: Preparation of additive-assisted aqueous phase synthesis of multi-component cationic perovskite δ-FA x M 1-x PbI3 solid solution; Step 1.1, Perovskite δ-FA containing additives x M 1-x The preparation method for the PbI3 solid solution reaction mixture is as follows: A certain amount of Pb(Ac)₂·3H₂O is added to a beaker, and hydroiodic acid diluted with excess deionized water is added dropwise (the concentration of the hydroiodic acid itself is 55-57%, and the concentration of hydroiodic acid after dilution with deionized water is controlled at 30%-45%). The mixture is stirred or ultrasonically vibrated continuously at 20-50℃ until all the white lead acetate is converted into yellow lead iodide. During this process, the molar ratio of hydroiodic acid to Pb(Ac)₂·3H₂O in the diluted hydroiodic acid solution is 6:1. Then, dopants such as CsI, RbI, or MAI iodide ions are added. After complete dissolution, 2,3,5,6-tetrafluoroterephthalonitrile is introduced as an additive, and the solution is heated to 20-60 °C. Stirring at temperature C for 1-3 days yields δ-FA with different cation ratios. x M 1-x PbI3 solid solution; during this process, PbI2 present in the reaction solution reacts with FAAc and iodoform salts in a strongly acidic environment, continuously producing a yellow precipitate, which is the target product δ-FA. x M 1-x PbI3 solid solution, after reacting fully for 1-3 days, stirring is stopped, at which point the reaction is complete; this process can be accelerated by the addition of additives.

[0031] In some specific examples, the molar ratio of Pb(Ac)2·3H2O to formamidine acetate (FAAc) is 1:(1.2-2), and the amount of iodoform salt added is 1%-100% of Pb(Ac)2·3H2O.

[0032] In some specific examples, iodophoric salts include inorganic iodides and organic iodides. Examples of inorganic iodides include CsI, RbI, KI, NaI, and CuI, while examples of organic iodides include PEAI, TBAI, and MAI.

[0033] In some specific examples, the content of 2,3,5,6-tetrafluoroterephthalonitrile is controlled at 0.5%-5% of the molar amount of lead acetate. Too high a concentration will have the opposite effect, while too low a concentration cannot be controlled. The effect is best within this range.

[0034] In the above process, an excess of formamidine acetate (FAAc) relative to lead acetate is beneficial for inhibiting the formation of the PbI2 phase; an excess of hydroiodic acid solution relative to lead acetate can maintain a low pH value in the reaction solution.

[0035] In this process, because it is an aqueous phase reaction, the potential barrier is lowered, resulting in a lower nucleation temperature. Therefore, the reaction temperature during stirring is relatively low, ranging from 20 to 60 degrees Celsius. C; Furthermore, the addition of additives can further regulate the crystallization process and shorten the time, so that the reaction time can be controlled within 1 day.

[0036] During this process, to ensure a certain level of acidity in the reaction solution, 1-2 mL of hydroiodic acid solution should be added to the reaction mixture every 4-8 hours.

[0037] Step 1.2, δ-FA x M 1-x Separation and purification of PbI3 perovskite solid solution; The δ-FA obtained in step 1.1 x M 1-x Solid-liquid separation was performed on the PbI3 mixture. Vacuum filtration was conducted using a sintered glass funnel combined with a suction flask to complete the solid-liquid separation, at which point a yellow powder was obtained on the surface of the sintered glass funnel. The yellow powder was then washed 3 to 5 times with an antisolvent to obtain high-purity yellow δ-FA. x M 1-x PbI3 perovskite solid solution. The antisolvent is ethyl acetate or acetonitrile.

[0038] Step 1.3, δ-FA x M 1-x Drying and storage of PbI3 perovskite solid solution.

[0039] The δ-FA obtained in step 1.2 x M 1-x The PbI3 perovskite solid solution was vacuum dried to remove excess antisolvent; the drying temperature was set at 30-60°C. Between C and . (Attached) Figure 1 For δ-FA x M 1-x A schematic diagram of the preparation process of PbI3.

[0040] δ-FA prepared by the above method x M 1-x The main crystalline phase of PbI3 (0≤x≤1) is δ-FA. x M 1-x The PbI3 perovskite crystal phase has 2,3,5,6-tetrafluoroterephthalonitrile adsorbed on its surface. This solid solution exhibits high stability in air, and the synthesis yield exceeds 90%. In this solution, FA is a formamidinium cation, and M is methylamine. + Cs + Various organic and inorganic cations.

[0041] The following is a further explanation with reference to specific embodiments: Example 1 S1. Weigh 3.79 g (10 mmol) of Pb(Ac)₂·3H₂O into a 50 mL beaker and add a stir bar. Weigh 13.70 g (60 mmol, calculated at a concentration of 56%) of a 55-57% hydroiodic acid solution, then dilute it with 20 mL of deionized water to obtain a diluted hydroiodic acid solution. Add the hydroiodic acid solution to the beaker containing Pb(Ac)₂·3H₂O. Stir at room temperature for 10 minutes until all the white Pb(Ac)₂·3H₂O is converted to yellow PbI₂. Then, slowly add 1.561 g (15 mmol) of FAAc and 0.1 g (0.5 mmol) of 2,3,5,6-tetrafluoroterephthalonitrile, and continue stirring at 30°C. Stir on a hot plate for 24 hours. During stirring, add 0.5 mL of 55-57% hydroiodic acid solution to the reaction solution every 4 hours.

[0042] S2, after stirring the reaction mixture for 24 hours, solid-liquid separation was first performed. Using vacuum filtration, unwashed yellow perovskite product was obtained on a sand core funnel. Subsequently, the yellow perovskite product was washed three times with ethyl acetate as a reverse solvent, with thorough stirring of the solid on the sand core funnel during the washing process. After three washes with the reverse solvent, a high-purity yellow δ-FAPbI3 perovskite solid solution was obtained.

[0043] S3, the washed yellow δ-FAPbI3 solid solution still contained some residual ethyl acetate, requiring vacuum drying to obtain a δ-FAPbI3 solid solution free of residual antisolvent. The washed δ-FAPbI3 solid solution was placed in a vacuum drying oven at 30 ºC for 24 hours. Finally, 5.74 g of dried δ-FAPbI3 solid solution was obtained, with a yield of 90.7%. The prepared δ-FAPbI3 solid solution was then vacuum-sealed and stored in a desiccator for later use.

[0044] From the appendix Figure 3 and 4 The powder X-ray diffraction pattern shows that at 11.8... The corresponding peak is the characteristic peak of δ-FAPbI3 (010), while there is no characteristic peak of PbI2 at 12.8, indicating that a pure phase δ-FAPbI3 yellow solid solution was obtained. Compared with the sample without additive control, the XRD pattern diffraction peaks are enhanced and the full width at half maximum (FWHM) is narrowed, which further indicates that the synthesized sample has fewer defects and stronger crystallinity.

[0045] Example 2 S1. Weigh 3.79 g (10 mmol) of Pb(Ac)₂·3H₂O into a 50 mL beaker and add a stir bar. Weigh 13.70 g (60 mmol, calculated at a concentration of 56%) of a 55-57% hydroiodic acid solution, then dilute it with 20 mL of deionized water to obtain a diluted hydroiodic acid solution. Add the hydroiodic acid solution to the beaker containing Pb(Ac)₂·3H₂O. Stir at room temperature for 10 minutes until all the white Pb(Ac)₂·3H₂O is converted to yellow PbI₂. Then, slowly add 1.483 g (14.25 mmol) of FAAc, 0.119 g (0.75 mmol) of MAI, and 0.1 g (0.5 mmol) of 2,3,5,6-tetrafluoroterephthalonitrile, and continue stirring at 30°C. Stir on a hot plate for 24 hours. During stirring, add 0.5 mL of 55-57% hydroiodic acid solution to the reaction solution every 6 hours.

[0046] S2, after stirring the reaction mixture for 24 hours, solid-liquid separation was first performed. Vacuum filtration was used to obtain unwashed yellow perovskite product on a sintered sand funnel. The yellow perovskite product was then washed three times with ethyl acetate as a reverse solvent, with thorough stirring of the solid on the sintered sand funnel during the washing process. After three repeated washings with ethyl acetate, high-purity yellow δ-FA was obtained. 0.95 MA 0.05 PbI3 perovskite solid solution.

[0047] S3, yellow δ-FA after washing 0.95 MA 0.05 The PbI3 solid solution still contains some residual ethyl acetate, which needs to be vacuum dried to obtain δ-FA without residual antisolvent. 0.95 MA 0.05 PbI3 solid solution. The washed δ-FA... 0.95 MA 0.05 The PbI3 solid solution was dried in a vacuum drying oven at 30 °C for 24 hours. Subsequently, the prepared δ-FA... 0.95 MA 0.05 The PbI3 solid solution was vacuum-sealed and stored in a desiccator for later use. The dried δ-FA was finally obtained. 0.95 MA 0.05 5.75 g of PbI3 solid solution was obtained, with a yield of 91.1%.

[0048] The δ-FA obtained by this preparation 0.95 MA 0.05 The XRD pattern of PbI3 solid solution is as follows: Figure 5As shown in the spectrum, the characteristic peaks of each product are obvious, with high peak intensities, and there are no impurity peaks, indicating that the phases are relatively pure.

[0049] Figure 6 For δ-FA 0.95 MA 0.05 Small-angle XRD pattern of PbI3 solid solution. The figure shows that with the increase in the size of the cation MA... + As the doping concentration increases, the lattice shrinks, and the characteristic peaks gradually shift towards larger angles, further confirming the presence of dual cations in the lattice.

[0050] Example 3 S1. Weigh 3.79 g (10 mmol) of Pb(Ac)₂·3H₂O into a 50 mL beaker and add a stir bar. Weigh 13.70 g (60 mmol, calculated at a concentration of 56%) of a 55-57% hydroiodic acid solution, then dilute it with 20 mL of deionized water to obtain a diluted hydroiodic acid solution. Add the hydroiodic acid solution to the beaker containing Pb(Ac)₂·3H₂O. Stir at room temperature for 10 minutes until all the white Pb(Ac)₂·3H₂O is converted to yellow PbI₂. Then, slowly add 1.483 g (14.25 mmol) of FAAc, 0.195 g (0.75 mmol) of CsI, and 0.1 g (0.5 mmol) of 2,3,5,6-tetrafluoroterephthalonitrile, and continue stirring at 30°C. Stir on a hot plate for 24 hours. During stirring, add 0.5 mL of 55-57% hydroiodic acid solution to the reaction solution every 6 hours.

[0051] S2, after stirring the reaction mixture for 24 hours, solid-liquid separation was first performed. Vacuum filtration was used to obtain unwashed yellow perovskite product on a sintered sand funnel. The yellow perovskite product was then washed three times with ethyl acetate as a reverse solvent, with thorough stirring of the solid on the sintered sand funnel during the washing process. After three repeated washings with ethyl acetate, high-purity yellow δ-FA was obtained. 0.95 Cs 0.05 PbI3 perovskite solid solution.

[0052] S3, yellow δ-FA after washing 0.95 Cs 0.05 The PbI3 solid solution still contains some residual ethyl acetate, which needs to be vacuum dried to obtain δ-FA without residual antisolvent. 0.95 Cs 0.05 PbI3 solid solution. The washed δ-FA... 0.95 Cs 0.05The PbI3 solid solution was dried in a vacuum drying oven at 30 °C for 24 hours. Subsequently, the prepared δ-FA... 0.95 Cs 0.05 The PbI3 solid solution was vacuum-sealed and stored in a drying cabinet for later use. The final dried FA was obtained. 0.95 Cs 0.05 5.84 g of PbI3 solid solution was obtained, with a yield of up to 91.7%.

[0053] The preparation process is simple and the preparation cost is low. The δ-FA obtained in this example 0.95 Cs 0.05 The microstructure of PbI3 solid solution is as follows: Figure 7 As shown in the figure, the grains without additive control exhibit inconsistent morphology and mutual adhesion, while the grains of the product grown with additive control show increased size and more uniform distribution, which further improves the quality of the product.

[0054] Example 4 S1. Weigh 3.79 g (10 mmol) of Pb(Ac)₂·3H₂O into a 50 mL beaker and add a stir bar. Dilute a 55-57% hydroiodic acid solution with deionized water to a concentration of 30%. Weigh the diluted hydroiodic acid solution (containing 60 mmol of HI) into the beaker and stir at 20 °C for 10 min to completely convert the white Pb(Ac)₂·3H₂O into yellow PbI₂. Then slowly add 2.081 g (20 mmol) of FAAc (molar ratio Pb:FAAc = 1:2), 0.0212 g (0.1 mmol) of RbI (1% iodine salt addition), and 0.0108 g (0.05 mmol) of 2,3,5,6-tetrafluoroterephthalonitrile (0.5% additive addition). Continue stirring at 20 °C for 48 h (2 days). During the reaction, 1 mL of 55-57% hydroiodic acid solution was added every 8 hours to maintain acidity.

[0055] S2. After the reaction is complete, the solid is separated by vacuum filtration. The solid product is washed three times with acetonitrile as the antisolvent, with thorough stirring each time.

[0056] S3, the washed yellow solid was dried in a vacuum drying oven at 30℃ for 24 h to obtain δ-FA. x Rb 1-x PbI3 solid solution (x ≈ 0.995). Weighed 5.82 g, yield approximately 92.3%.

[0057] Example 5 S1: Weigh 3.79 g (10 mmol) of Pb(Ac)₂·3H₂O into a 50 mL beaker and add a stir bar. Dilute a 55-57% hydroiodic acid solution with deionized water to a concentration of 45%. Weigh the diluted hydroiodic acid solution (containing 60 mmol of HI) into the beaker and stir at 50 °C for 10 min to completely convert the white Pb(Ac)₂·3H₂O into yellow PbI₂. Then slowly add 1.249 g (12 mmol) of FAAc (molar ratio 1:1.2), 2.598 g (10 mmol) of CsI (100% iodine salt addition), and 0.108 g (0.5 mmol) of 2,3,5,6-tetrafluoroterephthalonitrile (5% additive addition), and continue stirring at 60 °C for 72 h (3 days). During the reaction, add 2 mL of 55-57% hydroiodic acid solution every 4 h.

[0058] S2. After the reaction is complete, the solid is separated by vacuum filtration and washed three times with ethyl acetate.

[0059] S3, the washed yellow solid was dried in a vacuum drying oven at 30℃ for 24 h to obtain δ-FA. x Cs 1-x PbI3 solid solution (x ≈ 0.545). Weighed 5.79 g, yield approximately 91.5%.

[0060] Example 6 Weigh 3.79 g (10 mmol) of Pb(Ac)₂·3H₂O into a 50 mL beaker and add a stir bar. Dilute a 55-57% hydroiodic acid solution with deionized water to a concentration of 37.5%. Weigh the diluted hydroiodic acid solution (containing 60 mmol of HI) into the beaker and stir at 35 °C for 10 min to completely convert the white Pb(Ac)₂·3H₂O into yellow PbI₂. Then slowly add 1.665 g (16 mmol) of FAAc (molar ratio 1:1.6), 1.0618 g (5 mmol) of RbI (50% iodine salt addition), and 0.054 g (0.25 mmol) of 2,3,5,6-tetrafluoroterephthalonitrile (2.5% additive addition), and continue stirring at 40 °C for 60 h (2.5 days). During the reaction, 1.5 mL of 55-57% hydroiodic acid solution was added every 6 hours.

[0061] S2. After the reaction is complete, the solid is separated by vacuum filtration and washed three times with acetonitrile.

[0062] S3, the washed yellow solid was dried in a vacuum drying oven at 30℃ for 24 h to obtain δ-FA. x Rb 1-xPbI3 solid solution (x ≈ 0.762). Weighed 5.80 g, yield approximately 91.8%.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An additive-assisted aqueous phase synthesis of multi-component cationic perovskite δ-FA x M 1-x The method for PbI3 solid solution is characterized by... Includes the following steps: S1, Pb(Ac)2·3H2O is dissolved in a diluted aqueous solution of hydroiodic acid and stirred to form PbI2; S2, formamidine acetate, iodoform salt, and 2,3,5,6-tetrafluoroterephthalonitrile are added, and the reaction is stirred continuously to generate δ-FA. x M 1- x PbI3 mixture; S3, perform solid-liquid separation on the reaction solution, and wash the solid product with an antisolvent; S4, the washed solid product was dried under vacuum to obtain δ-FA. x M 1-x PbI3 (0≤x≤1) solid solution.

2. The additive-assisted aqueous synthesis of multi-component cationic perovskite δ-FA according to claim 1 x M 1-x The method for PbI3 solid solution is characterized by... In S1, the stirring temperature is 20-50℃.

3. The additive-assisted aqueous synthesis of multi-component cationic perovskite δ-FA according to claim 1 x M 1-x The method for PbI3 solid solution is characterized by... The concentration of the diluted hydroiodic acid aqueous solution is 30%-45%, and the molar ratio of hydroiodic acid to Pb(Ac)2·3H2O in the diluted hydroiodic acid solution is 6:

1.

4. The additive-assisted aqueous synthesis of multi-component cationic perovskite δ-FA according to claim 1 x M 1-x The method for PbI3 solid solution is characterized by... In S2, the molar ratio of Pb(Ac)2·3H2O to formamidine acetate is 1:(1.2-2).

5. The additive-assisted aqueous synthesis of multi-component cationic perovskite δ-FA according to claim 1 x M 1-x The method for PbI3 solid solution is characterized by... In S2, the molar amount of the iodo-based ion salt added is 1%-100% of the molar amount of Pb(Ac)2·3H2O.

6. The additive-assisted aqueous synthesis of multi-component cationic perovskite δ-FA according to claim 1 x M 1-x The method for PbI3 solid solution is characterized by... In S2, the amount of 2,3,5,6-tetrafluoroterephthalonitrile added is 0.5%-5% of the molar amount of Pb(Ac)2·3H2O.

7. The additive-assisted aqueous synthesis of multi-component cationic perovskite δ-FA according to claim 1 x M 1-x The method for PbI3 solid solution is characterized by... In S2, the reaction temperature is 20-60°C. C, the reaction time is 1-3 days.

8. The additive-assisted aqueous phase synthesis of multi-component cationic perovskite δ-FA according to claim 1 x M 1-x The method for PbI3 solid solution is characterized by... In S2, 1-2 mL of 55-57% hydroiodic acid solution is added every 4-8 hours during the reaction to maintain the acidity of the reaction solution.

9. The additive-assisted aqueous synthesis of multi-component cationic perovskite δ-FA according to claim 1 x M 1-x The method for PbI3 solid solution is characterized by... In S3, the antisolvent is ethyl acetate or acetonitrile.

10. An additive-assisted aqueous phase synthesis method for multi-component cationic perovskite δ-FA obtained by the method according to any one of claims 1-9 x M 1-x PbI3 solid solution, characterized in that... The delta-FA x M 1-x The surface of the perovskite crystal in the PbI3 solid solution is adsorbed with 2,3,5,6-tetrafluoroterephthalonitrile.

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