Method for preparing high purity cesium-based perovskite powder

Abstract

The present invention relates to a method for preparing cesium-based perovskites, more particularly to a method for synthesizing cesium-based perovskites with high yield and high purity, and to a cesium-based perovskite prepared by using the method.

Description

Technical Field

[0001] This invention relates to a method for preparing cesium-based perovskite powder with high purity and the high-purity cesium-based perovskite prepared by said method. Background Technology

[0002] To address the global environmental problems caused by the depletion and use of fossil fuels, research is actively underway on renewable and clean alternative energy sources, such as solar, wind, and hydropower.

[0003] Among these energy sources, there is a significant increase in interest in solar cells, which directly convert sunlight into electricity. Here, a solar cell refers to a battery that generates current and voltage by utilizing the photovoltaic effect, which produces electrons and holes by absorbing light energy from sunlight.

[0004] Currently, it is possible to manufacture NP diode-based silicon (Si) single-crystal solar cells with a light-to-energy conversion efficiency exceeding 20%, and these are actually being used in solar power generation. There are also solar cells using compound semiconductors such as gallium arsenide (GaAs) with even higher conversion efficiencies. However, these inorganic semiconductor-based solar cells require highly purified materials to achieve high efficiency, thus consuming significant energy in refining raw materials. Furthermore, the manufacturing of single crystals or thin films using these raw materials requires expensive processing equipment, limiting the potential for reducing the manufacturing cost of solar cells and hindering their large-scale utilization.

[0005] Therefore, in order to manufacture solar cells at low cost, it is necessary to significantly reduce the cost of materials or manufacturing processes used as core components of solar cells, and research is being conducted on perovskite solar cells that can be manufactured using low-cost materials and processes as an alternative to inorganic semiconductor-based solar cells.

[0006] The general structural formula of perovskite is ABX3, in which the anion is located at the X site, the large cation is located at the A site, and the small cation is located at the B site.

[0007] To tune the bandgap of FAPbI3-based perovskite materials to suit silicon tandem solar cells, mixing with CsPbBr3 is necessary. Adding wide-bandgap CsPbBr3 (approximately 3.82 eV) to narrower-bandgap FAPbI3 (approximately 1.48 eV) allows for tuning to a perovskite material suitable for tandem cells (approximately 1.66 eV). CsPbBr3 is widely used due to its high solubility and ease of production. However, Oxford PV holds a prior patent for producing perovskites under the aforementioned conditions. Therefore, methods for tuning perovskites beyond those described above are needed.

[0008] Generally, there are methods to control the band gap of perovskites by modulating the A site and the halide X site. In the case of the A site, it is controlled by methylammonium (MA), formamidinium (FA), cesium (Cs), etc., and research and attempts are underway to introduce cesium-based perovskites, such as CsPbBr3, into FA-based FAPbI3, which has high efficiency and high stability, and to commercialize the modified product.

[0009] As inorganic metal halide materials, perovskites with a CsPbX3 (X = Cl, Br, or I) structure possess a broad spectrum from approximately 410 nm to 700 nm, and have the advantage of being able to absorb across the entire visible range and exhibit a variety of fluorescent colors by adjusting the constituent elements. Therefore, they are very promising candidates for various optoelectronic devices, such as lasers, displays, solar cells, and photoelectric sensors. Summary of the Invention

[0010] Technical issues

[0011] The present invention aims to provide a method for preparing cesium-based perovskites with high purity and high reproducibility by optimizing the chemical composition of the precursors used in the preparation of cesium-based perovskites, as well as the cesium-based perovskites prepared therefrom.

[0012] Technical solution

[0013] To address the aforementioned problems, the present invention provides a method for preparing cesium-based perovskites, the method comprising the following steps: Step 1, preparing a first precursor aqueous solution by dissolving a cesium halide compound represented by Chemical Formula 1 in water, and preparing a second precursor solution by dissolving a lead halide compound represented by Chemical Formula 2 in an organic solvent; Step 2, introducing the first precursor aqueous solution into the second precursor solution and reacting to obtain a precipitate as a reaction product; and Step 3, purifying and drying the obtained precipitate to obtain a cesium-based perovskite represented by Chemical Formula 3.

[0014] [Chemical Formula 1]

[0015] CsX (1-a) X' a

[0016] [Chemical Formula 2]

[0017] PbX (3-a)

[0018] [Chemical Formula 3]

[0019] CsPbX (3-a) X' a

[0020] In Chemical Formula 1 to Chemical Formula 3, a is a rational number satisfying 0 < a ≤ 1, and X and X' are independently -Cl or -Br.

[0021] In a preferred embodiment of the present invention, the organic solvent in Step 1 may include one or more selected from dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dimethylacetamide (DMAc), dimethylimidazolidinone (DMI), γ - butyrolactone (GBL), and 2 - methoxyethanol (2Me).

[0022] In a preferred embodiment of the present invention, the second precursor solution in Step 1 may have a lead halide compound concentration of 0.005 M to 1.00 M.

[0023] In a preferred embodiment of the present invention, the first precursor aqueous solution in Step 1 may have a cesium halide compound concentration of 1.0 M or greater.

[0024] In a preferred embodiment of the present invention, Step 2 may mix and react the first precursor in the first precursor aqueous solution and the second precursor in the second precursor solution so as to have a molar ratio of 1:0.8 to 1.0.

[0025] In a preferred embodiment of the present invention, the reaction in Step 2 may be carried out under environmental conditions of 15°C to 35°C.

[0026] In a preferred embodiment of the present invention, the cesium - based perovskite obtained in Step 3 may have a yield of 75.0% to 99.5% and a purity of 99.00% or greater.

[0027] Another object of the present invention is to provide high - purity cesium - based perovskite powder, which is prepared by the above - mentioned method and may have a purity of 99.00% or greater.

[0028] Yet another object of the present invention relates to a perovskite composite, which is perovskite powder using the cesium - based perovskite prepared by the above - mentioned method, and the perovskite composite may be a perovskite represented by the following Chemical Formula 4.

[0029] [Chemical Formula 4]

[0030] Cs a MX b X' (3-b)

[0031] In Chemical Formula 4, M is a divalent cation and includes one or both selected from Fe, Co, Ni, Cu, Sn, Pb, Bi, Ge, Ti, Eu, and Zr, and X and X' are independently Cl, Br, or I (where X and X' are different halogen elements), a is an integer where 0 < a ≤ 1, and b is an integer where 0 < a ≤ 3.

[0032] In addition, another object of the present invention is to provide a perovskite solar cell including the perovskite complex as a light absorption layer (or a photoactive layer).

[0033] Advantageous Effects

[0034] The method for preparing a cesium-based perovskite according to the present invention can produce a high-purity cesium-based perovskite with high reproducibility and high yield, thereby providing a cesium-based perovskite with excellent economic feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] [[ID=1,4]] Figure 1a and Figure 1b are photographs of the cesium-based perovskites prepared in Examples 1 to 5.

[0036] Figure 2 are photographs of the first precursor solution (A), the second precursor solution (B), and after mixing and reacting them (C) taken in Comparative Example 1.

[0037] Figure 3 are photographs of the first precursor solution (A), the second precursor solution (B), and after mixing and reacting them (C) taken in Comparative Example 2.

[0038] Figure 4a and Figure 4b are X-ray diffraction (XRD) measurement data of the cesium-based perovskites prepared in Examples 1 to 5.

[0039] Figure 5a and Figure 5b are thermogravimetric analysis (TGA) measurement data of the cesium-based perovskites prepared in Examples 1 to 5. DETAILED DESCRIPTION

[0040] Hereinafter, the present invention will be described in more detail.

[0041] The present invention relates to a method for preparing a high-purity cesium-based perovskite with a purity of 99.00% or greater at a high yield, and can be produced by performing the following process.

[0042] For the cesium-based perovskite powder of the present invention, a process including the following steps is performed: Step 1, prepare a first precursor aqueous solution by dissolving a cesium halide compound represented by Chemical Formula 1 in water, and prepare a second precursor solution by dissolving a lead halide compound represented by Chemical Formula 2 in an organic solvent; Step 2, introduce the first precursor aqueous solution into the second precursor solution and react to obtain a precipitate as a reaction product; and Step 3, purify and dry the obtained precipitate to obtain a cesium-based perovskite represented by the following Chemical Formula 3.

[0043] [Chemical Formula 1]

[0044] CsX (1-a) X' a

[0045] [Chemical Formula 2]

[0046] PbX (3-a)

[0047] [Chemical Formula 3]

[0048] CsPbX (3-a) X'<着 a

[0049] In Chemical Formulas 1 to 3, a is a rational number satisfying 0 < a ≤ 1, preferably a rational number satisfying 0.30 < a ≤ 1, and more preferably a rational number satisfying 0.40 < a ≤ 1. In addition, X and X' are the same or different halogens and are independently -Cl or -Br.

[0050] The organic solvent used in preparing the second precursor solution in Step 1 may include one or more selected from dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dimethylacetamide (DMAc), dimethylimidazolidinone (DMI), γ-butyrolactone (GBL), and 2-methoxyethanol (2Me), preferably one or more selected from DMF, DMSO, DMI, and 2Me, and more preferably one or more selected from DMF, DMSO, and DMI.

[0051] In addition, the concentration of the lead halide compound in the second precursor solution may be 0.005 M to 1.00 M, preferably 0.005 M to 0.600 M, and more preferably 0.010 M to 0.200 M. In this case, if the concentration of the lead halide compound is less than 0.02 M, the yield and purity of the cesium-based perovskite as the final reaction product may be low, while if it is greater than 1.0 M, there may be a problem of reaching the solubility limit.

[0052] Furthermore, more specifically, when X in Formula 2 is -Cl, the concentration of the lead halide compound in the second precursor solution can be from 0.005 M to 0.050 M, and preferably from 0.010 M to 0.030 M. Furthermore, when X in Formula 1 is -Br, the concentration of the lead halide compound in the second precursor solution can be from 0.02 M to 0.60 M, and preferably from 0.02 M to 0.20 M.

[0053] Furthermore, the concentration of cesium halide compounds in the first precursor aqueous solution can be 1.0 M or greater, preferably 1.0 M to 2.0 M, and more preferably 1.0 M to 1.5 M. In this case, since water (which is the solvent of the first precursor aqueous solution) is also used as the antisolvent of the final reaction product, it is advantageous to synthesize high-purity cesium-based perovskites when the concentration of cesium halide compounds meets the above range. However, if the concentration of cesium halide compounds in the first precursor aqueous solution is greater than 2.0 M, the yield and purity of the cesium-based perovskites as the final reaction product may be lower.

[0054] Furthermore, more specifically, when X in Formula 1 is -Br, the concentration of the cesium halide compound in the first precursor aqueous solution can be from 1.00 M to 2.00 M, and preferably from 1.00 M to 1.50 M. Furthermore, when X in Formula 1 is -Cl, the concentration of the cesium halide compound in the first precursor solution can be from 1.00 M to 1.80 M, and preferably from 1.00 M to 1.60 M.

[0055] Next, step 2 involves mixing and reacting the second precursor solution and the first precursor aqueous solution to synthesize a precipitate as the reaction product. In step 2, the first precursor in the first precursor aqueous solution and the second precursor in the second precursor solution can be mixed and reacted at a molar ratio of 1:0.8 to 1.0, and preferably 1:0.9 to 1.0. In this case, if the molar ratio of the second precursor to the first precursor is less than 0.8 or greater than 1.0, the purity of the cesium-based perovskite as the final reaction product may be reduced due to unreacted impurities; therefore, mixing and reacting at the aforementioned ratio is preferred.

[0056] In addition, step 2 can be carried out under environmental conditions of 15°C to 35°C.

[0057] Additionally, in step 2, after the reaction is complete, filtration can be performed to obtain a precipitate as a reaction product.

[0058] Furthermore, the purification in step 3 can be carried out by general methods used in the art, and as a preferred embodiment, the precipitate obtained by filtration can be purified 3 to 4 times with a ketone solution (e.g., acetone, dimethyl ketone or propanone) and then filtered again to obtain powder.

[0059] Furthermore, the powder obtained through purification can be dried using conventional drying methods (e.g., thermal drying) to prepare cesium-based perovskites.

[0060] Furthermore, as described above, the cesium-based perovskite obtained in step 3 can have a yield of 70.0% or greater and a purity of 98.00% or greater, preferably a yield of 75.0% to 99.5% and a purity of 99.00% or greater, and more preferably a yield of 75.8% to 99.0% and a purity of 99.00% to 99.90%.

[0061] The invention will be described in more detail below by way of examples, but the following examples do not limit the scope of the invention and should be interpreted as helpful in understanding the invention.

[0062] [Example]

[0063] Example 1: Preparation of cesium-based perovskite powder

[0064] A first precursor aqueous solution with a concentration of 1.30 M was prepared by dissolving CsBr powder (5.78 g), which is a cesium halide compound, in ultrapure water (DI water).

[0065] A lead halide compound powder (10.03 g), which is represented by the following chemical formula 2-1, was dissolved in DMF to prepare a second precursor solution with a concentration of 0.27 M.

[0066] [Chemical Formula 2-1]

[0067] PbX (3-a)

[0068] In chemical formula 2-1, X is -Br and a is 1.

[0069] Next, while the second precursor solution was slowly stirred at 22°C to 23°C, the aqueous solution of the first precursor was added dropwise to the second precursor solution, and the reaction was carried out while stirring for another 2 hours. The mixture was then allowed to stand to form a precipitate, which was then filtered to obtain an orange precipitate. In this case, the molar ratio of the first precursor to the second precursor was 1:1.

[0070] Next, the obtained precipitate was purified three times with acetone, filtered again to obtain a powder, and then dried in a hot drying oven to obtain 13.32 g of cesium-based perovskite powder represented by the following chemical formula 3-1. A photograph of the obtained powder is shown below. Figure 1a middle.

[0071] Furthermore, the yield and purity of the synthesized cesium-based perovskite powder are shown in Table 3.

[0072] [Chemical Formula 3-1]

[0073] CsPbX (3-a) (X') a

[0074] In chemical formula 3-1, a is 1, and X and X' are -Br.

[0075] Example 2: Preparation of cesium-based perovskite powder

[0076] A first precursor aqueous solution with a concentration of 1.48 M was prepared by dissolving 5.0 g of CsCl powder in ultrapure water (DI water).

[0077] A lead halide compound powder (11 g), which is represented by the following chemical formula 2-1, was dissolved in DMF to prepare a second precursor solution with a concentration of 0.27 M.

[0078] [Chemical Formula 2-1]

[0079] PbX (3-a)

[0080] In chemical formula 2-1, X is -Br and a is 1.

[0081] Next, while the second precursor solution was slowly stirred at 22°C to 23°C, the aqueous solution of the first precursor was added dropwise to the second precursor solution, and the reaction was carried out while stirring for another 2 hours. The mixture was then allowed to stand to form a precipitate, which was then filtered to obtain a yellow precipitate. In this case, the molar ratio of the first precursor to the second precursor was 1:1.

[0082] Next, the obtained precipitate was purified three times with acetone, filtered again to obtain a powder, and then dried in a hot drying oven to obtain 13.01 g of cesium-based perovskite powder represented by the following chemical formula 3-2. A photograph of the obtained powder is shown below. Figure 1a middle.

[0083] Furthermore, the yield and purity of the synthesized cesium-based perovskite powder are shown in Table 3.

[0084] [Chemical Formula 3-2]

[0085] CsPbX (3-a) (X') a

[0086] In chemical formula 3-2, a is 1, X is -Br, and X' is -Cl.

[0087] Example 3: Preparation of cesium-based perovskite powder

[0088] 3.0 g of CsBr powder was dissolved in ultrapure water (DI water) to prepare a first precursor aqueous solution with a concentration of 1.4 M.

[0089] A lead halide compound powder (3.98 g), which is represented by the following chemical formula 2-2, was dissolved in DMF to prepare a second precursor solution with a concentration of 0.02 M.

[0090] [Chemical Formula 2-2]

[0091] PbX (3-a)

[0092] In chemical formula 2-2, X is -Cl, and a is 1.

[0093] Next, the aqueous solution of the first precursor was added to the solution of the second precursor, and the mixture was stirred for 2 hours at 22°C to 23°C to allow the reaction to proceed. The mixture was then allowed to stand to form a precipitate, which was subsequently filtered to obtain a pale yellow precipitate. In this case, the molar ratio of the first precursor to the second precursor was 1:1.

[0094] Next, the obtained precipitate was purified three times with acetone, filtered again to obtain a powder, and then dried in a hot drying oven to obtain 5.31 g of cesium-based perovskite powder represented by the following chemical formula 3-3. A photograph of the obtained powder is shown below. Figure 1a middle.

[0095] Furthermore, the yield and purity of the synthesized cesium-based perovskite powder are shown in Table 3.

[0096] [Chemical Formula 3-3]

[0097] CsPbX (3-a) (X') a

[0098] In chemical formula 3-3, a is 2, X is -Br, and X' is -Cl.

[0099] Example 4: Preparation of cesium-based perovskite powder

[0100] A first precursor aqueous solution with a concentration of 1.57 M was prepared by dissolving 7.95 g of CsCl powder in ultrapure water (DI water).

[0101] A second precursor solution with a concentration of 0.02 M was prepared by dissolving a lead halide compound powder (13.13 g) as a compound represented by the following chemical formulas 1-3 in DMF.

[0102] [Chemical Formulas 1-3]

[0103] PbX (3-a)

[0104] In chemical formulas 1-3, X is -Cl, and a is 1.

[0105] Next, the aqueous solution of the first precursor was added to the solution of the second precursor, and the mixture was stirred for 2 hours at 22°C to 23°C to allow the reaction to proceed. The mixture was then allowed to stand to form a precipitate, which was subsequently filtered to obtain a white precipitate. In this case, the molar ratio of the first precursor to the second precursor was 1:1.

[0106] Next, the obtained precipitate was purified three times with acetone, filtered again to obtain a powder, and then dried in a hot drying oven to obtain 20.70 g of cesium-based perovskite powder represented by the following chemical formulas 3-4. A photograph of the obtained powder is shown below. Figure 1a middle.

[0107] Furthermore, the yield and purity of the synthesized cesium-based perovskite powder are shown in Table 3.

[0108] [Chemical Formula 3-4]

[0109] CsPbX (3-a) (X') a

[0110] In chemical formula 3-4, a is 1, X is -Cl, and X' is -Cl.

[0111] Example 5: Preparation of cesium-based perovskite powder

[0112] 13.8 g of CsBr powder from Preparation Example 1 used in Example 1 and 8.4 g of CsCl powder from Preparation Example 2 used in Example 2 were dissolved in ultrapure water (DI water) to prepare a first precursor aqueous solution with a concentration of 1.3 M.

[0113] In the same manner as in Example 1, 3.6 g of the lead halide compound powder represented by the above chemical formula 1-1 was dissolved in DMF to prepare a second precursor solution with a concentration of 0.27 M.

[0114] Next, the aqueous solution of the first precursor was added to the solution of the second precursor, and the mixture was stirred for 2 hours at 22°C to 23°C to allow the reaction to proceed. The mixture was then allowed to stand to form a precipitate, which was subsequently filtered to obtain a deep yellow precipitate. In this case, the molar ratio of the first precursor to the second precursor was 1:1.

[0115] Next, the obtained precipitate was purified three times with acetone, filtered again to obtain a powder, and then dried in a hot drying oven to obtain 3.0249 g of cesium-based perovskite powder represented by the following chemical formulas 3-5. A photograph of the obtained powder is shown below. Figure 1b middle.

[0116] Furthermore, the yield and purity of the synthesized cesium-based perovskite powder are shown in Table 1.

[0117] [Chemical Formula 3-5]

[0118] CsPbX (3-a) (X') a

[0119] In chemical formulas 3-5, a is 0.5, X is -Br, and X' is -Cl.

[0120] [Table 1]

[0121]

[0122] Comparative Example 1

[0123] CsBr powder (5.78 g) was dissolved in DMF to prepare a first precursor solution with a concentration of 1.30 M (see [link to DMF]). Figure 2 A).

[0124] A lead halide compound powder (10.03 g), represented by the following chemical formula 2-1, was dissolved in DMF to prepare a second precursor solution with a concentration of 0.27 M (see [link to DMF]). Figure 2 (B in the middle).

[0125] [Chemical Formula 2-1]

[0126] PbX (3-a)

[0127] In chemical formula 2-1, X is -Br and a is 1.

[0128] Next, while the second precursor solution was slowly stirred at 22°C to 23°C, the aqueous solution of the first precursor was added dropwise to the second precursor solution, followed by an additional 2 hours of stirring. Even after an additional hour of stirring, no reaction occurred (see [link to product description]). Figure 2 (C).

[0129] This is because only the solvent (DMF) and no antisolvent are present in the first and second precursor mixture, so no reaction occurs.

[0130] Comparative Example 2

[0131] CsBr powder (5.78 g) was dissolved in ultrapure water (DI water) to prepare a first precursor aqueous solution with a concentration of 1.30 M (see [link to original text]). Figure 3 A).

[0132] When 10.03 g of a lead halide compound powder, represented by the following chemical formula 2-1, was added to ultrapure water (DI water) and stirred, the lead halide compound powder did not dissolve in the water (see [link to relevant documentation]). Figure 3 (see B in the original text), and no reaction occurred even when the aqueous solution of the first precursor was added dropwise (see B in the original text). Figure 3 (C in the middle).

[0133] Experimental example: XRD and TGA measurements

[0134] XRD and TGA were measured for each cesium-based perovskite powder prepared in Examples 1 to 5, and the results are shown in... Figure 4a (Examples 1 to 4) Figure 4b (Example 5) Figure 5a (Examples 1 to 4) and Figure 5b In (Example 5).

[0135] observe Figure 4a and Figure 4b XRD measurements confirmed that as Br was replaced by Cl, the XRD position gradually shifted from around 21° to higher angles. This is because the lattice constant decreases as the amount of Cl, which is smaller than Br, increases.

[0136] In addition, when observing Figure 5a and Figure 5b During TGA measurements, no weight loss was observed except in segment 1 (where weight loss begins at approximately 600°C), indicating that the material is well-bonded and contains no other substances besides a single component. Furthermore, it was confirmed that the weight loss segment gradually shifts to higher temperatures with increasing Cl content.

[0137] Example 6 and Comparative Examples 3 to 5

[0138] The perovskite compound represented by CsPbBr2Cl was prepared using the same method as in Example 2, but the concentrations of the first precursor in the first precursor aqueous solution or the second precursor in the second precursor aqueous solution were varied, as shown in Table 4 below. Examples 6 and 7 and Comparative Examples 2 and 3 were performed respectively. Furthermore, the yields and purities of the synthesized perovskite compounds are shown in Table 2.

[0139] [Table 2]

[0140]

[0141] Observing Table 2 above, Examples 2 and 6 show results that satisfy both high yields of 70% or greater and high purity of 95% or greater. In contrast, in Comparative Example 3, where the concentration of the first precursor aqueous solution is greater than 2.00 M, the concentration of the first precursor aqueous solution becomes too high, resulting in a relatively insufficient amount of antisolvent, leading to a significant decrease in yield. Furthermore, reaction products such as PbBr3 are generated and precipitated, resulting in both low yield and low purity. Additionally, in Comparative Examples 4 and 5, where the concentration of the first precursor aqueous solution is less than 1.00 M, although the purity is high, the overall yield is poor. This is determined to be because the final product is dissolved in DMF, which serves as the solvent for the second precursor solution.

[0142] Through the above embodiments and experimental examples, it was confirmed that high-purity cesium-based perovskites can be prepared in high yield.

Claims

1. A method for preparing cesium-based perovskites, characterized in that... Perform a process including the following steps: Step 1, prepare a first precursor aqueous solution by dissolving a cesium halide compound represented by Chemical Formula 1 in water, and prepare a second precursor solution by dissolving a lead halide compound represented by Chemical Formula 2 in an organic solvent; Step 2, introduce the first precursor aqueous solution into the second precursor solution and react to obtain a precipitate as a reaction product; And Step 3, purify and dry the obtained precipitate to obtain a cesium-based perovskite represented by the following Chemical Formula 3; [Chemical Formula 1] CsX (1-a) X' a [Chemical Formula 2] PbX (3-a) [Chemical Formula 3] CsPbX (3-a) X' a Where in Chemical Formulas 1 to 3, a is a rational number satisfying 0 < a ≤ 1, and X and X' are independently -Cl or -Br.

2. The method according to claim 1, wherein the organic solvent in Step 1 includes one or more selected from dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dimethylacetamide (DMAc), dimethylimidazolidinone (DMI), γ-butyrolactone (GBL), and 2-methoxyethanol (2Me).

3. The method according to claim 1, wherein the second precursor solution has a lead halide compound concentration of 0.005 M to 1.000 M.

4. The method according to claim 1, wherein the first precursor aqueous solution has a cesium halide compound concentration of 1.0 M or greater.

5. The method according to claim 1, wherein Step 2 mixes and reacts the first precursor in the first precursor aqueous solution and the second precursor in the second precursor solution such that they have a molar ratio of 1:0.8 to 1.

0.

6. The method according to claim 1, wherein the reaction in Step 2 is carried out under environmental conditions of 20°C to 35°C.

7. The method according to claim 1, wherein the cesium-based perovskite obtained in Step 3 has a yield of 75.0% to 99.5% and a purity of 99.00% or greater.

8. A cesium-based perovskite powder, prepared by the method according to any one of claims 1 to 7, and having a purity of 99.00% or greater.

9. A perovskite composite, prepared by using the cesium-based perovskite according to claim 8, the perovskite composite being a perovskite represented by the following Chemical Formula 4; [Chemical Formula 4] Cs a MX b X' (3-b) Where in Chemical Formula 4, M is a divalent cation and includes one or both selected from Fe, Co, Ni, Cu, Sn, Pb, Bi, Ge, Ti, Eu, and Zr, and X and X' are independently Cl, Br, or I (where X and X' are different halogen elements), a is an integer of 0 < a ≤ 1, and b is an integer of 0 < a ≤ 3.

Images