Method for preparing perovskite single crystal by using general solvent system

Abstract

The invention discloses a method for preparing a perovskite single crystal by using a general solvent system, and relates to the field of photoelectric materials. The general solvent system is composed of gamma-butyrolactone and polyethylene glycol and can be used for preparing perovskite single crystals with various components. The method for preparing the perovskite single crystal by using the solvent system comprises the following steps: preparing a perovskite precursor solution; heating the perovskite precursor solution; and taking out the single crystal from the solution, cleaning and drying. The method is simple and convenient to operate, and can be used for preparing large-size single crystals and preparing small-size single crystals on a large scale.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic materials, and mainly to a method for preparing perovskite single crystals by using a universal solvent system. Background Art

[0002] In recent years, organic-inorganic hybrid perovskite materials have received unprecedented attention. Their molecular formula is ABX3, where the A-site ion is usually methylamine (MA + ), formamidine (FA + )、Cs + , the B-site ion is Pb 2+ and Sn 2+ , the X-site ion is a halogen anion (Cl - Br - ,I - ). Perovskite is widely used in solar cells, light-emitting diodes, photodetectors, lasers and other fields due to its excellent photoelectric properties, such as high absorption coefficient, long carrier lifetime and high carrier mobility. In addition, perovskite can be prepared by solution method, which saves production cost and time cost, and well meets the commercialization needs, so it has good application prospects.

[0003] Compared with conventional polycrystalline thin films, perovskite single crystals have lower defect density, higher carrier diffusion length and better stability, so higher performance optoelectronic devices can be achieved. Today, perovskite single crystals are often used in visible-ultraviolet photodetectors, X-ray detectors, and gamma-ray detectors, and they show extremely high competitive advantages in the medical and aerospace fields. At present, the preparation of perovskite single crystals can usually be carried out by inverse temperature crystallization, cooling method, anti-solvent vapor assisted crystallization method, solvent evaporation method, etc. Among these methods, the inverse temperature crystallization method has become one of the current mainstream synthesis methods because of its advantages such as simple operation, good crystallinity and short time consumption.

[0004] The principle of the inverse temperature crystallization method is that the solubility of perovskite decreases with increasing temperature. Therefore, by heating the perovskite precursor solution to allow the solute to precipitate and crystallize, a single crystal material can be obtained. However, current research has found that the solvents that can achieve inverse temperature crystallization are very limited, and the solvents required for perovskites of different components are also different. For example, the solvent required for MAPbI3 single crystals is γ-butyrolactone, and the solvent required for MAPbBr3 single crystals is N,N-dimethylformamide. The limitations of solvent selection are not conducive to its application in complex devices, let alone its large-scale preparation in industry.

[0005] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a method for preparing perovskite single crystals using a universal solvent system. First, the solvent system can be used for the preparation of perovskite single crystals of various components, reducing the steps of frequently changing solvents when preparing perovskites of different components, and reducing production time and cost. Secondly, perovskite has a large solubility in the solvent system, which is conducive to industrial mass production and improves production efficiency. The specific contents of the present invention are as follows: In the first aspect, the present invention provides a simple and effective universal solvent system, which is composed of γ-butyrolactone and polyethylene glycol. In the solvent system, the proportion of polyethylene glycol is selected in the range of 10%-90%; and the molecular weight of polyethylene glycol is selected in the range of 200-200000.

[0007] In addition, polyethylene glycol can be replaced by other crown ether substances, and γ-butyrolactone can be replaced by N,N-dimethylformamide, dimethyl sulfoxide, and acetonitrile.

[0008] In a second aspect, the present invention provides a method for preparing a perovskite single crystal using the universal solvent system, comprising the following steps: S1. Fully dissolving the solute of the perovskite precursor solution in the solvent system to prepare the perovskite precursor solution; S2, heating the perovskite precursor solution; S3. Take out the single crystal from the solution, wash it and dry it.

[0009] The method for preparing a perovskite single crystal using a universal solvent system, wherein step S1 comprises the following sub-steps: S11, preparing solutes AX and BX2 of a perovskite precursor solution, wherein AX includes MAI, FAI, CsI, MABr, FABr, CsBr, MACl, FACl, CsCl, and BX2 includes PbI2, PbBr2, PbCl2, SnI2, SnBr2, SnCl2; S12, preparing a solvent system for a perovskite precursor solution; S13, dissolving the solute of the precursor solution in step S11 in the solvent system in step S12 to prepare a perovskite precursor solution with a concentration of 0.1-3 mol / L.

[0010] In the method for preparing a perovskite single crystal using a universal solvent system, the molar ratio of AX to BX2 in step S11 is in the range of 2:1 to 1:2.

[0011] The method for preparing a perovskite single crystal using a universal solvent system, wherein step S2 comprises the following sub-steps: S21, filtering the perovskite precursor solution, then transferring it into a clean container, and sealing the container; S22, heating the solution to precipitate crystals, the heating temperature can be between 40-200° C., and the heating time is 2-48 hours.

[0012] The method for preparing a perovskite single crystal using a universal solvent system, wherein step S3 comprises the following sub-steps: S31, taking out the single crystal from the solution; S32, cleaning the residual solution on the surface of the crystal; S33, drying the crystals, the drying temperature can be 60-150°C, and the drying time can be 2-24 hours.

[0013] The method for preparing perovskite single crystals using a universal solvent system, wherein the solvent used for cleaning in step S32 includes dichloromethane, chloroform, chlorobenzene, toluene, isopropanol, ethyl acetate, and n-hexane.

[0014] In a third aspect, the solvent system provided by the present invention has the following beneficial effects: 1. The solvent system can be used to prepare perovskite single crystals of various components, such as organic-inorganic hybrid perovskite, all-inorganic perovskite, perovskites of different halogens, lead-based perovskites, tin-based perovskites, etc.; 2. The solvent system can also be used for mixed ion perovskite single crystals, such as mixed A-site ion perovskite, mixed halogen ion perovskite, mixed tin-lead-based perovskite, etc.; 3. The solvent system has a variety of composition options, such as the proportion of polyethylene glycol and the type of polyethylene glycol, which have a wide range of choices; 4. The solvent system has a simple process for preparing perovskite single crystals and has excellent crystal quality; 5. This solvent system can be combined with other processes to prepare more complex optoelectronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the present invention. The following drawings only illustrate certain embodiments of the present invention and should not be regarded as improper limitations of the present invention. In the drawings: Figure 1-Figure 6 The solubility of perovskites with different components in a universal solvent system changes with temperature, where the content of polyethylene glycol is 50%; Figure 7 The X-ray diffraction pattern of FAPbI3 perovskite single crystal prepared using a universal solvent system; Figure 8 This is the X-ray diffraction pattern of FAPbBr3 perovskite single crystal prepared using a universal solvent system. DETAILED DESCRIPTION

[0016] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The components of the present invention generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0017] The present invention provides a method for preparing perovskite single crystals using a universal solvent system, thereby achieving the convenient preparation of perovskite single crystals with various components; Specifically, the present invention provides a method for preparing a perovskite single crystal using a universal solvent system, comprising the following steps: S1, using γ-butyrolactone and polyethylene glycol to prepare a perovskite precursor solution; S2, placing the perovskite precursor solution on a heating table for heating; S3. Taking out the single crystal from the solution, washing and drying it, thereby obtaining a perovskite single crystal material.

[0018] In some preferred embodiments, step S1 comprises the following sub-steps: S11, weighing AX and BX2 with a molar ratio of 1:1 respectively as solutes of the precursor solution; S12, preparing γ-butyrolactone and polyethylene glycol, and fully mixing the two in a certain ratio as a solvent system of the precursor solution; S13, adding the solute weighed in step S11 to the solvent system in step S12, and fully dissolving it at room temperature to form a perovskite precursor solution of a certain concentration.

[0019] In some preferred embodiments, step S2 comprises the following sub-steps: S21. Use a syringe to absorb the dissolved precursor solution, filter it, transfer it to a clean glass bottle, and cover the glass bottle with a lid or perform other sealing treatments; S22. Place the glass bottle on a heating table and slowly increase the temperature until a small amount of crystals appear. Maintain the temperature for 3 hours to allow the reaction to complete. Then continue to slowly increase the temperature until the crystals grow to the desired size.

[0020] Wherein, in step S21, a 0.45 micron organic filter head is selected for filtration.

[0021] Wherein, in step S22, the rate of slow heating is 5-10 ° C / h; In step S22, the temperature may be quickly raised to the final desired temperature to prepare a large number of small-sized single crystals.

[0022] In some preferred embodiments, step S3 includes the following sub-steps: S31, after stopping the reaction, quickly cool the solution and take out the perovskite single crystal in time to prevent the single crystal from re-dissolving; S32, washing the single crystal with an anti-solvent to remove the residual solution and attached solute powder; S33. Place the cleaned single crystal in an oven at 80°C, dry for 6 hours, take it out, and seal it for storage.

[0023] Among them, in step S32, the anti-solvent used for cleaning can be selected from isopropanol, toluene, ethyl acetate, etc.

[0024] The present invention provides a method for preparing perovskite single crystals using a universal solvent system, which combines γ-butyrolactone and polyethylene glycol to form a universal solvent system that can be used to prepare perovskite single crystals of different components. In addition, it can also be used to prepare mixed ion type perovskite single crystals, and has the characteristics of simple operation. According to the rate of heating, large-sized single crystals can be prepared or a large number of small-sized single crystals can be quickly synthesized.

[0025] This method can be combined with other processes to prepare more complex and diverse optoelectronic devices.

[0026] The present invention is further described below by means of specific examples.

[0027] Embodiment 1: S1. Weigh FAI and PbI2 with a molar ratio of 1:1, take 5 ml of γ-butyrolactone and 5 ml of polyethylene glycol (i.e., the polyethylene glycol content is 50%) as the solvent system, and finally fully dissolve FAI and PbI2 at room temperature to prepare a FAPbI3 perovskite precursor solution with a concentration of 3 M; S2, take out the solution, filter it with a 0.45 micron organic filter head, then transfer it to a 50 ml wide-mouth glass bottle, cover it with a lid, place it on a heating table preheated to 50°C, then increase the temperature at a rate of 10°C / h, start to precipitate crystals at about 55°C, maintain the temperature for 3h, and then continue to increase the temperature at a rate of 5°C / h until the crystals grow to the desired size; S3. Remove the glass bottle from the heating table, take out the crystals with tweezers, rinse them with isopropanol, dry them in a 150°C oven for 6 hours, and finally vacuum seal them for storage.

[0028] Figure 1-Figure 6The solubility curves of different perovskite compositions in the solvent system vary with temperature. Figure 4 It is FAPbI3 perovskite, and its solubility decreases with increasing temperature after 40°C, so crystallization can be precipitated by increasing the temperature.

[0029] Figure 7 The figure shows the X-ray diffraction pattern of the prepared FAPbI3 perovskite single crystal, with peaks only at around 20° and 40°, corresponding to the (110) and (220) crystal planes, respectively, indicating that the crystal has good orientation, good crystallinity, and no impurities.

[0030] Embodiment 2: S1. Weigh FABr and PbBr2 with a molar ratio of 1:1, take 5 ml of γ-butyrolactone and 5 ml of polyethylene glycol (i.e., the polyethylene glycol content is 50%) as the solvent system, and finally fully dissolve FABr and PbBr2 at room temperature to prepare a FAPbBr3 perovskite precursor solution with a concentration of 1.0 M; S2, take out the solution, filter it with a 0.45 micron organic filter head, then transfer it to a 50 ml wide-mouth glass bottle, cover it with a lid, place it on a heating table preheated to 40°C, then heat it at a rate of 10°C / h, start to crystallize at about 45°C, maintain the temperature for 3h, and then continue to heat it at a rate of 5°C / h until the crystals grow to the desired size; S3. Remove the glass bottle from the heating table, take out the crystals with tweezers, rinse them with isopropanol, dry them in a 60°C oven for 6 hours, and finally vacuum seal them for storage.

[0031] Figure 1-Figure 6 The solubility curves of different perovskite compositions in the solvent system vary with temperature. Figure 5 It is FAPbBr3 perovskite, whose solubility decreases with increasing temperature, so crystallization can be precipitated by increasing the temperature.

[0032] Figure 8 The figure shows the X-ray diffraction pattern of the prepared FAPbBr3 perovskite single crystal, with peaks only at around 15°, 30° and 45°, corresponding to the (100), (200) and (300) crystal planes, respectively, indicating that the crystal has good orientation, good crystallinity and no impurities.

[0033] Embodiment 3: S1. Weigh FAI and PbI2 with a molar ratio of 2:1, take 1 ml of γ-butyrolactone and 9 ml of polyethylene glycol (i.e., the polyethylene glycol content is 90%) as the solvent system, and finally fully dissolve FAI and PbI2 at room temperature to prepare a FAPbI3 perovskite precursor solution with a concentration of 1.5 M; S2, take out the solution, filter it with a 0.45 micron organic filter head, then transfer it to a 50 ml wide-mouth glass bottle, cover it with a lid, and place it on a heating table preheated to 120°C, maintaining the temperature for 5 hours, so that the crystals can nucleate and grow; S3. Remove the glass bottle from the heating table, take out the crystals with tweezers, rinse them with isopropanol, dry them in a 100°C oven for 6 hours, and finally vacuum seal them for storage.

[0034] Embodiment 4: S1. Weigh FABr and PbBr2 with a molar ratio of 1:2, take 9 ml of γ-butyrolactone and 1 ml of polyethylene glycol (i.e., the polyethylene glycol content is 10%) as the solvent system, and finally fully dissolve FAI and PbI2 at room temperature to prepare a FAPbBr3 perovskite precursor solution with a concentration of 0.1 M; S2, take out the solution, filter it with a 0.45 micron organic filter head, then transfer it to a 50 ml wide-mouth glass bottle, cover it with a lid, and place it on a heating table preheated to 200°C, maintaining the temperature for 5 hours, so that the crystals can nucleate and grow; S3. Remove the glass bottle from the heating table, take out the crystals with tweezers, rinse them with isopropanol, dry them in a 60°C oven for 6 hours, and finally vacuum seal them for storage.

[0035] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A universal solvent system, characterized in that: The solvent system consists of gamma-butyrolactone and polyethylene glycol, and the content of the polyethylene glycol ranges from 10% to 90%.

2. A method for preparing a perovskite single crystal using the universal solvent system of claim 1, comprising the following sub-steps: S1. Fully dissolving the solute of the perovskite precursor solution in the solvent system to prepare the perovskite precursor solution; S2, heating the perovskite precursor solution; S3. Take out the single crystal from the solution, wash it and dry it.

3. The method for preparing a perovskite single crystal according to claim 2, characterized in that: Step S1 includes the following sub-steps: S11, preparing solutes AX and BX2 of a perovskite precursor solution, wherein AX includes MAI, FAI, CsI, MABr, FABr, CsBr, MACl, FACl, CsCl, and BX2 includes PbI2, PbBr2, PbCl2, SnI2, SnBr2, SnCl2; S12, preparing a solvent system for a perovskite precursor solution; S13, dissolving the solute of the precursor solution in step S11 in the solvent system in step S12 to prepare a perovskite precursor solution with a concentration of 0.1-3 mol / L.

4. The method for preparing a perovskite single crystal according to claim 3, characterized in that: In step S11, the ratio of the amount of substances of AX and BX2 is in the range of 2:1 to 1:

2.

5. The method for preparing a perovskite single crystal according to claim 2, characterized in that: Step S2 includes the following sub-steps: S21, filtering the perovskite precursor solution, then transferring it into a clean container, and sealing the container; S22, heating the solution to precipitate crystals, wherein the heating temperature is between 40-200°C.

6. The method for preparing a perovskite single crystal according to claim 2, characterized in that: Step S3 includes the following sub-steps: S31, taking out the single crystal from the solution; S32, cleaning the residual solution on the surface of the crystal; S33, drying the crystals, the drying temperature may be 60-150°C.

7. The method for preparing a perovskite single crystal according to claim 6, characterized in that: The solvent used for cleaning in step S32 includes dichloromethane, chloroform, chlorobenzene, toluene, isopropanol, ethyl acetate, and n-hexane.

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