Large-size perovskite single crystal and preparation method thereof

Abstract

A large-size perovskite single crystal and a preparation method thereof belong to the technical field of perovskite and overcome the defects that it is difficult to obtain large-size and high-quality single crystal particles in the prior art.The preparation method of the large-size perovskite single crystal adopts a mixed solution of GBL and GVL as a solvent, and grows a single crystal through inverse temperature crystallization; wherein GBL is gamma-butyrolactone, GVL is gamma-valerolactone, and the volume ratio of GBL to GVL is 1:(1.5-2.5). The perovskite single crystal prepared by the method has large size and high stability, and the method can also reduce the harm to the environment and health caused by the use of GBL.

Description

Technical Field

[0001] This invention belongs to the field of perovskite technology, specifically relating to a large-size perovskite single crystal and its preparation method. Background Technology

[0002] Hybrid perovskite materials (PSCs) have attracted widespread attention due to their excellent photoelectric properties (e.g., low exciton binding energy, low-temperature fabrication, long carrier diffusion length, high mobility, wide spectral response range, tunable bandgap, and low internal voltage loss) and high power conversion efficiency (PCE > 26%). However, industrially fabricated perovskite thin films contain numerous grain boundaries with a large number of defects, which restrict carrier migration, accelerate internal ion migration, and accelerate perovskite decomposition at low temperatures, ultimately reducing device PCE and operational stability. Therefore, perovskite single crystals offer significant advantages: lower defect state density leads to higher carrier mobility, a wider absorption spectrum, and suppressed ion migration. These advantages ensure that perovskite solar cells maintain high efficiency while also exhibiting better stability.

[0003] Currently, most perovskite single crystals are grown using methods such as inverted temperature crystallization (ITC), cooled temperature crystallization (LTC), and antisolvent vapor-assisted crystallization (AVC). Compared to ITC, LTC is more time-consuming for growing large-size single crystals, and AVC still faces challenges in this area. Therefore, ITC is a method that can rapidly obtain large-size perovskite single crystals. Common solvents used in ITC are γ-butyrolactone (GBL) and 2-methoxyethanol (2-Me). However, studies have shown that GBL residues remain in the internal spaces of single crystals grown in GBL, which can actually accelerate the kinetic phase transition and reduce crystal stability. In 2-Me, only single-crystal powder can be obtained, making it impossible to prepare large-size single crystals. Furthermore, GBL and 2-Me are low-toxicity reagents; large-scale use of GBL and 2-Me can pollute the environment and harm human health.

[0004] Existing technologies use GVL instead of GBL to grow single crystals, but the resulting single crystals are small in size and irregular in shape, making it difficult to obtain large-sized, high-quality single crystal particles. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defect of the prior art in that it is difficult to obtain large-size, high-quality single crystal particles, thereby providing a large-size perovskite single crystal and its preparation method.

[0006] To this end, the present invention provides the following technical solution.

[0007] In a first aspect, the present invention discloses a method for preparing large-size perovskite single crystals, using a mixture of GBL and GVL as a solvent, and growing single crystals by a reverse temperature crystallization method;

[0008] GBL stands for γ-butyrolactone, and GVL stands for γ-valerolactone. The volume ratio of GBL to GVL is 1:(1.5~2.5). Specifically, this is the volume ratio under ambient temperature (25℃) and atmospheric conditions.

[0009] Furthermore, the reverse temperature crystallization method includes the following steps:

[0010] Step 1: Mix GBL and GVL to prepare a solvent, add ABX3 raw material to the solvent according to the stoichiometric ratio, stir, and prepare a single crystal growth solution;

[0011] The raw materials for perovskite ABX3 refer to the raw materials that can be used to prepare perovskite quantum dots with the general formula ABX3.

[0012] A can be Cs + MA + FA + At least one of them; B can be Pb 2+ Zn 2+ Cd 2+ Cu 2+ Mg 2+ At least one of them; X can be Cl - , Br - and I - At least one of them;

[0013] Step 2: Heat the single crystal growth solution to prepare seed crystals;

[0014] Step 3: Transfer the seed crystal to a new single crystal growth solution for growth. The new single crystal growth solution is the same as the single crystal growth solution obtained in Step 1.

[0015] Step 4: Repeat the process of transferring the seed crystal to a new single crystal growth solution until a perovskite single crystal of the target size is obtained. The seed crystal is transferred to a new single crystal growth solution when a certain preset condition is met, such as when the seed crystal reaches a certain size or when the concentration of the current single crystal growth solution is reduced to a certain value.

[0016] Furthermore, in step 1, the stirring time is 10–20 hours to ensure the solute is fully dissolved. For example, stirring for 10 hours, 12 hours, or 20 hours.

[0017] Furthermore, in step 1, ABX3 is Cs x FA 1-xPbI3, where 0 ≤ x < 0.15. For example, x is 0.01, 0.02, 0.05, or 0.10.

[0018] Cs x FA 1-x The raw materials for PbI3 include CsI, FAI, and PbI2.

[0019] Furthermore, taking ABX3 as an example, the molar concentration of the single crystal growth solution is ≥90% of the room temperature saturation concentration, that is, the molar concentration of the single crystal growth solution (taking ABX3 as an example) is more than 90% of the saturation concentration (under room temperature conditions).

[0020] To grow single crystals using the inverse temperature crystallization method, it is necessary to find the saturation concentration of the solution, and then use a solution with a near-saturation concentration to grow the single crystal. Typically, solutions of different concentrations are prepared and their solubility is observed. When the solution is unsaturated, it exhibits a clear appearance; when the solution is supersaturated, undissolved solute can be seen.

[0021] In one possible design, the concentration of the single crystal growth solution, expressed as ABX3, is 1–1.5 M.

[0022] Furthermore, step 2 includes: holding the single crystal growth solution at 35℃~55℃ for 3h~6h, then raising the temperature until crystals begin to appear in the single crystal growth solution, continuing to raise the temperature by 10~15℃, and then holding it at that temperature for 0~3h. In step 2, after raising the temperature by 10~15℃, it can be held at that temperature; alternatively, it can be skipped (i.e., held for 0h) and proceed directly to step 3, transferring the crystal to a new single crystal growth solution for continued growth. However, as the holding time increases, the concentration of the single crystal growth solution decreases. When it reaches a certain value, the solution concentration is insufficient for the single crystal to continue growing, and even recrystallization may occur. Therefore, the holding time is controlled within 3h.

[0023] Furthermore, in step 2, the heating rate at which crystals begin to appear in the single crystal growth solution is 3–6 °C / h, for example, 5 °C / h; the heating rate for continued heating is 3–6 °C / h, for example, 5 °C / h.

[0024] Furthermore, in step 3, the growth conditions are: holding at 60-70℃ (the same temperature at which crystals begin to appear) for 1-3 hours, and then gradually increasing the temperature at a certain rate (e.g., 3℃ / h) until the temperature reaches 70-80℃.

[0025] Furthermore, in step 1, the solution is filtered after stirring to obtain the single crystal growth solution. Filtration is performed to prevent minute impurities in the solution from increasing the nucleation sites of the single crystal, which could lead to the precipitation of more small crystal fragments during the single crystal growth process.

[0026] Furthermore, filtration can be performed using a filter with a pore size of 0.2–1 μm, such as polytetrafluoroethylene (PTFE) with a pore size of 0.22 μm or 0.45 μm. If the pore size is too small (nanoscale), the filtration time will be longer; if the pore size is too large, impurities will not be filtered out completely.

[0027] Furthermore, in step 4, step 3 to 4 is repeated to transfer the seed crystal to a new single crystal growth solution for growth.

[0028] Secondly, the present invention provides a large-size perovskite single crystal prepared according to the above method.

[0029] Furthermore, the size of large-size perovskite single crystals is ≥14mm, for example, 15mm~20mm.

[0030] The technical solution of this invention has the following advantages:

[0031] 1. The present invention provides a method for preparing large-size perovskite single crystals, which uses a mixture of GBL and GVL as a solvent and grows single crystals by inverted temperature crystallization; wherein GBL is γ-butyrolactone, GVL is γ-valerolactone, and the volume ratio of GBL to GVL is 1:(1.5~2.5).

[0032] In the process of growing perovskite single crystals using the reverse-temperature crystallization method, the crystallization temperature of perovskite is lower in GVL compared to GBL. The introduction of green solvent (GVL) can significantly reduce the growth temperature of perovskite crystals during reverse-temperature crystallization, tighten the temperature variation range of single crystal growth, and facilitate temperature control during single crystal growth, thereby obtaining single crystals with fewer defects and higher purity. Furthermore, perovskite single crystals obtained using a mixture of GBL and GVL as a solvent do not undergo phase transformation after a period of time, exhibiting higher stability compared to those using GBL alone. Simultaneously, it can reduce the environmental and health hazards associated with the use of GBL, promote the commercial development of perovskite, and provide a favorable technological direction for achieving high-quality perovskite crystallization. This method also has extremely high commercial value, enabling the large-scale production of high-quality perovskite photovoltaic modules, enriching product varieties, and expanding commercial reach. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 The perovskite single crystal prepared in Example 1;

[0035] Figure 2 The image shows the perovskite single crystal prepared in Example 1 after being exposed to air for 7 days.

[0036] Figure 3 The image shows the XRD pattern of the perovskite single crystal obtained in Example 1.

[0037] Figure 4 The image shows the XRD pattern of the perovskite single crystal prepared in Example 1 after exposure to air for 7 days.

[0038] Figure 5 The perovskite single crystal prepared in Comparative Example 1;

[0039] Figure 6 The image shows the perovskite single crystal prepared in Comparative Example 1 after being exposed to air for 7 days.

[0040] Figure 7 The XRD pattern of the perovskite single crystal prepared in Comparative Example 1 after exposure to air for 7 days is shown.

[0041] Figure 8 The perovskite single crystal prepared in Comparative Example 2;

[0042] Figure 9 The perovskite single crystal prepared in Comparative Example 3;

[0043] Figure 10 The perovskite single crystal prepared in Comparative Example 4;

[0044] Figure 11 This is a perovskite single crystal prepared in Comparative Example 5. Detailed Implementation

[0045] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0046] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0047] Example 1

[0048] This embodiment provides a method for preparing large-size perovskite single crystals, including the following steps:

[0049] Step 1: Using a mixture of GBL and GVL in a volume ratio of 1:2 as the solvent, add Cs according to the stoichiometric ratio. 0.05 FA 0.95 The raw materials CsI, FAI, and PbI2 for PbI3 were added to the above solvent and stirred for 12 hours. The mixture was then filtered through polytetrafluoroethylene (PTFE) with a pore size of 0.45 μm to obtain the concentration (in CsI). 0.05 FA 0.95 The single crystal growth solution (based on PbI3) is 1.2 M (in this example, the room temperature saturation concentration is approximately 1.25 M).

[0050] Step 2: Transfer the single crystal growth solution to an oven at 45°C and keep it at 45°C for 5 hours. Then, slowly increase the temperature from 45°C at a rate of 5°C / h. When the temperature reaches 65°C, three regular small crystals appear in the solution. In order to increase the crystal size, continue to increase the temperature by 15°C at a rate of 5°C / h.

[0051] Step 3: To obtain a large-sized single crystal, select a regular small crystal from Step 2 as a seed crystal and transfer it to a new Cs solution with a concentration of 1.2 M. 0.05 FA 0.95 In the PbI3 single crystal growth solution, the temperature was kept at 65℃ for 1 hour, and then the temperature was increased to 80℃ at a rate of 3℃ / h.

[0052] Step 4 involves two separate steps of transferring the crystal to a new single crystal growth solution for growth (i.e., transferring the crystal obtained in Step 3 as a seed crystal to a new single crystal growth solution, holding it at 65°C for 1 hour, and then raising the temperature to 80°C at a rate of 3°C / h; then transferring the crystal obtained in the above steps as a seed crystal to a new single crystal growth solution, holding it at 65°C for 1 hour, and then raising the temperature to 80°C at a rate of 3°C / h).

[0053] In this embodiment, steps 3 and 4 were performed for a total of 3 growth cycles to obtain a regular, large-sized crystal, such as... Figure 1 As shown.

[0054] The XRD pattern of the large-size perovskite single crystal obtained in this embodiment is shown in the figure below. Figure 3 As shown, this embodiment has grown Cs. 0.05 FA 0.95 The single crystals of PbI3 are of high quality and do not contain intermediate phases (such as δ phase).

[0055] Comparative Example 1

[0056] This comparative example provides a method for preparing perovskite single crystals, including the following steps:

[0057] Step 1: Using GBL as a solvent, add Cs according to the stoichiometric ratio. 0.05 FA0.95 The raw materials CsI, FAI, and PbI2 for PbI3 were added to the above solvent and stirred for 12 hours. The mixture was then filtered through polytetrafluoroethylene (PTFE) with a pore size of 0.45 μm to obtain the concentration (in CsI). 0.05 FA 0.95 The single crystal growth solution (based on PbI3) is 1.5 M (the room temperature saturation concentration in this comparative example is approximately 1.65 M).

[0058] Step 2: Transfer the single crystal growth solution to an oven at 60°C and keep it at 60°C for 5 hours. Then, slowly increase the temperature from 60°C at a rate of 5°C / h. When the temperature reaches 100°C, there are two small crystals in the solution. In order to increase the crystal size, gradually increase the temperature by 15°C.

[0059] Step 3: To obtain a large-sized single crystal, select a small crystal from Step 2 as a seed crystal and transfer it to fresh Cs at a concentration of 1.5 M. 0.05 FA 0.95 In the PbI3 single crystal growth solution, the temperature was kept at 100℃ for 1 hour, and then the temperature was increased to 115℃ at a rate of 3℃ / h.

[0060] Step 4, transferring the crystal to a new single-crystal growth solution, is repeated twice.

[0061] The perovskite single crystal obtained after three growth cycles in steps 3 and 4 of this comparative example is shown below. Figure 5 As shown in the figure. In this comparative example, due to the high growth temperature and wide crystallization temperature range of the single crystal, the grown single crystal is irregular and has many defects.

[0062] Comparative Example 2:

[0063] This comparative example provides a method for preparing perovskite single crystals, including the following steps:

[0064] Step 1: Using GVL as a solvent, add Cs according to the stoichiometric ratio. 0.05 FA 0.95 The raw materials CsI, FAI, and PbI2 for PbI3 were added to the above solvent and stirred for 12 hours. The mixture was then filtered through polytetrafluoroethylene (PTFE) with a pore size of 0.45 μm to obtain the concentration (in CsI). 0.05 FA 0.95 Cs (calculated as PbI3) is 0.9 M. 0.05 FA 0.95 PbI3 single crystal growth solution (in this example, the room temperature saturation concentration is approximately 1 M).

[0065] Step 2: Transfer the filtered solution to an oven at 30°C and keep it at 30°C for 5 hours. Then, slowly increase the temperature from 30°C at a rate of 5°C / hour. When the temperature reaches 55°C, some small crystals appear in the solution. To increase the crystal size, gradually increase the temperature by 15°C.

[0066] Step 3: Select one small crystal from Step 2 as a seed crystal and transfer it to fresh Cs solution with a concentration of 0.9 M. 0.05 FA 0.95 In the PbI3 single crystal growth solution, the temperature was kept at 55℃ for 1 hour, and then the temperature was increased to 70℃ at a rate of 3℃ / h.

[0067] Step 4, transferring the crystal to a new single-crystal growth solution, is repeated twice.

[0068] The perovskite single crystal obtained after three growth cycles in steps 3 and 4 of this comparative example is shown below. Figure 8 As shown, many small crystals precipitate during the single crystal growth process, making it difficult for the single crystal to grow, and the resulting single crystals have irregular shapes.

[0069] Comparative Example 3

[0070] This comparative example provides a method for preparing perovskite single crystals, including the following steps:

[0071] Step 1: Using a 2:1 GBL / GVL mixed solvent, add Cs according to the stoichiometric ratio. 0.05 FA 0.95 The raw materials CsI, FAI, and PbI2 for PbI3 were added to the above solvent and stirred for 12 hours. The mixture was then filtered through polytetrafluoroethylene (PTFE) with a pore size of 0.45 μm to obtain the concentration (in CsI). 0.05 FA 0.95 The single crystal growth solution (based on PbI3) is 1.3 M (in this example, the room temperature saturation concentration is approximately 1.4 M).

[0072] Step 2: Transfer the filtered solution to an oven at 55°C and keep it at 55°C for 5 hours. Then, slowly increase the temperature from 55°C at a rate of 5°C / h. When the temperature reaches 90°C, some small crystals appear in the solution. In order to increase the crystal size, gradually increase the temperature by 15°C.

[0073] Step 3: Select one small crystal from Step 2 as a seed crystal and transfer it to fresh Cs solution with a concentration of 1.3 M. 0.05 FA 0.95 In the PbI3 single crystal growth solution, the temperature was kept at 90℃ for 1 hour, and then the temperature was increased to 105℃ at a rate of 3℃ / h.

[0074] Step 4, transferring the crystal to a new single-crystal growth solution, is repeated twice.

[0075] The perovskite single crystal obtained after three growth cycles in steps 3 and 4 of this comparative example is shown below. Figure 8 As shown, many small crystals precipitate during single crystal growth, which is not conducive to single crystal growth. Therefore, it is difficult for single crystals to grow, and the resulting single crystals have irregular shapes.

[0076] The perovskite single crystal obtained after three growth cycles in steps 3 and 4 of this comparative example is shown below. Figure 9 As shown. During the single crystal growth process, many small crystals will precipitate, making it difficult for single crystals to grow, and the resulting single crystals are irregular.

[0077] Comparative Example 4

[0078] This comparative example provides a method for preparing perovskite single crystals, including the following steps:

[0079] Step 1: Using a 1:1 GBL / GVL mixed solvent, add Cs according to the stoichiometric ratio. 0.05 FA 0.95 The raw materials CsI, FAI, and PbI2 for PbI3 were added to the above solvent and stirred for 12 hours. The mixture was then filtered through polytetrafluoroethylene (PTFE) with a pore size of 0.45 μm to obtain the concentration (in CsI). 0.05 FA 0.95 The single crystal growth solution (based on PbI3) is 1.2 M (in this example, the room temperature saturation concentration is approximately 1.3 M).

[0080] Step 2: Transfer the filtered solution to an oven at 50°C and keep it at 50°C for 5 hours. Then, slowly increase the temperature from 50°C at a rate of 5°C / h. When the temperature reaches 80°C, some small crystals appear in the solution. In order to increase the crystal size, gradually increase the temperature by 15°C.

[0081] Step 3: To obtain a large-sized single crystal, select a small crystal from Step 2 as a seed crystal and transfer it to fresh Cs at a concentration of 1.2 M. 0.05 FA 0.95 In the PbI3 single crystal growth solution, the temperature was kept at 80℃ for 1 hour, and then the temperature was increased to 95℃ at a rate of 3℃ / h.

[0082] Step 4, transferring the crystal to a new single-crystal growth solution, is repeated twice.

[0083] The perovskite single crystal obtained after three growth cycles in steps 3 and 4 of this comparative example is shown below. Figure 10 As shown. During the single crystal growth process, many small crystals will precipitate, making it difficult for single crystals to grow, and the resulting single crystals are irregular.

[0084] Comparative Example 5

[0085] This comparative example provides a method for preparing perovskite single crystals, including the following steps:

[0086] Step 1: Using a 1:3 GBL / GVL mixed solvent, add Cs according to the stoichiometric ratio. 0.05 FA 0.95 The raw materials CsI, FAI, and PbI2 for PbI3 were added to the above solvent and stirred for 12 hours. The mixture was then filtered through polytetrafluoroethylene (PTFE) with a pore size of 0.45 μm to obtain the concentration (in CsI). 0.05 FA 0.95 The single crystal growth solution (based on PbI3) is 1M (in this example, the room temperature saturation concentration is approximately 1.1M).

[0087] Step 2: Transfer the filtered solution to an oven at 35°C and keep it at 35°C for 5 hours. Then, slowly increase the temperature from 35°C at a rate of 5°C / h. When the temperature reaches 60°C, some small crystals appear in the solution. In order to increase the crystal size, gradually increase the temperature by 15°C.

[0088] Step 3: To obtain a large-sized single crystal, select a small crystal from Step 2 as a seed crystal and transfer it to fresh Cs with a concentration of 1M. 0.05 FA 0.95 In the PbI3 single crystal growth solution, the temperature was kept at 75℃ for 1 hour, and then the temperature was increased to 75℃ at a rate of 3℃ / h.

[0089] Step 4, transferring the crystal to a new single-crystal growth solution, is repeated twice.

[0090] The perovskite single crystal obtained after three growth cycles in steps 3 and 4 of this comparative example is shown below. Figure 11 As shown. During the single crystal growth process, many small crystals will precipitate, making it difficult for single crystals to grow, and the resulting single crystals are irregular.

[0091] Test case

[0092] The stability of the perovskite single crystals prepared in Example 1 and Comparative Example 1 was tested using the following method:

[0093] 1. Expose the perovskite single crystal to air for 7 days and observe the color change of the single crystal. When the perovskite single crystal turns yellow, it indicates that the perovskite single crystal has transformed from the α phase to the δ phase, thus indicating that the generated single crystal α phase is unstable.

[0094] 2. XRD tests were performed on perovskite single crystals exposed to air for 7 days, and δ phases were generated in the yellowed single crystals.

[0095] The test results of Example 1 are shown below. Figure 2 , Figure 4 The test results for Comparative Example 1 are shown below. Figure 6 , Figure 7 The test results show that the perovskite monomer prepared in Comparative Example 1 turned yellow after being exposed to air for 7 days, and the XRD pattern showed a peak of the δ phase. The perovskite single crystal prepared in Example 1 of this invention did not undergo the transformation from the α phase to the δ phase after being exposed to air for 7 days, and there was no δ phase in the XRD pattern. The perovskite single crystal prepared by this invention has good stability.

[0096] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing large-size perovskite single crystals, characterized in that, Single crystals were grown by reverse temperature crystallization using a mixture of GBL and GVL as a solvent. GBL is γ-butyrolactone, GVL is γ-valerolactone, and the volume ratio of GBL to GVL is 1:

2. The method for preparing the large-size perovskite single crystal includes the following steps: Step 1: Mix GBL and GVL to prepare a solvent, add the perovskite ABX3 raw material to the solvent according to the stoichiometric ratio, stir, and prepare a single crystal growth solution; Step 2: Heat the single crystal growth solution to prepare seed crystals; Step 3: Transfer the seed crystal to a new single crystal growth solution for growth. The new single crystal growth solution is the same as the single crystal growth solution obtained in Step 1. Step 4: Repeat the step of transferring the seed crystal to a new single crystal growth solution for growth until a perovskite single crystal of the target size is obtained; In step 1, ABX3 is Cs 0.05 FA 0.95 PbI3.

2. The method for preparing large-size perovskite single crystals according to claim 1, characterized in that, Based on ABX3, the molar concentration of the single crystal growth solution is ≥90% of the room temperature saturation concentration.

3. The method for preparing large-size perovskite single crystals according to claim 1, characterized in that, Step 2 includes: keeping the single crystal growth solution at 35℃~55℃ for 3h~6h, then gradually increasing the temperature until crystals begin to appear in the single crystal growth solution, continuing to increase the temperature by 10~15℃, and then keeping it at that temperature for 0~3h.

4. The method for preparing large-size perovskite single crystals according to claim 1, characterized in that, In step 3, the growth conditions are: keep warm at 60~70℃ for 1~3 hours, and then gradually increase the temperature at a certain rate until the temperature reaches 70℃~80℃.

5. The method for preparing large-size perovskite single crystals according to claim 1, characterized in that, In step 1, the solution is stirred and then filtered to obtain the single crystal growth solution.

6. The method for preparing large-size perovskite single crystals according to claim 5, characterized in that, Use a filter screen with a pore size of 0.2~1μm for filtration.

7. A large-size perovskite single crystal prepared by the method according to any one of claims 1-6.

8. The large-size perovskite single crystal according to claim 7, characterized in that, Large-size perovskite single crystals have a size ≥14mm.

Images