Preparation method for realizing growth of ultralow-defect perovskite single crystal based on steric hindrance control

Abstract

The invention belongs to the technical field of semiconductor photoelectric devices, and particularly discloses a preparation method for realizing growth of ultralow-defect perovskite single crystals based on steric hindrance control, which comprises the following steps: preparing a perovskite single crystal precursor solution: dissolving a perovskite single crystal precursor in a homogeneous solvent with coordination capability to prepare the precursor solution; and generating a perovskite single crystal seed crystal: heating the prepared perovskite single crystal precursor solution until microcrystals appear, selecting to form good crystals, drying, and storing as the seed crystal for future use. And growing the perovskite single crystal: putting the generated perovskite single crystal seed crystal into the perovskite single crystal precursor solution, heating, and growing to obtain the perovskite single crystal. The preparation method comprises the following steps: dissolving a precursor in a homogeneous solvent with coordination capability through a temperature reversal crystallization method, and adjusting the temperature to carry out single crystal growth; according to the steric hindrance theory, the growth temperature is selected by regulating and controlling the solvent proportion, and the perovskite single crystal with ultralow defect density is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor optoelectronic devices, and in particular relates to a preparation method for growing ultra-low defect perovskite single crystals based on steric control. Background Art

[0002] In recent years, the semiconductor material perovskite has been widely used in the fields of photoelectric detection and photovoltaics due to its excellent properties such as high absorption coefficient, high carrier mobility, long carrier diffusion length and band engineering. At present, microcrystalline or polycrystalline perovskite films have been prepared, and their performance is already very good, but there are inevitably grain boundaries and surface defects, which will lead to obvious current-voltage (JV) curve hysteresis and the decline of important photoelectric properties such as carrier mobility. Single crystal perovskite has excellent properties such as lower defect state density, longer carrier diffusion length, and higher carrier mobility than polycrystalline perovskite, making it an ideal material for preparing high-performance optoelectronic devices.

[0003] At present, the shortcomings of perovskite single crystals are mainly reflected in high defect density and poor stability. Although the inversion crystallization growth strategy is cost-effective, it has problems such as low solute utilization and toxic solvents. When using the inversion crystallization method to grow perovskite single crystal materials, a single, toxic solvent is usually used. The interaction between the solvent and the solute is the basis for the growth of perovskite single crystals by the inversion crystallization method, which determines the quality of the grown sample and the performance of optoelectronic devices. We have developed a mixed green solvent system and grown perovskite single crystals with ultra-low trap density and high stability at room temperature by controlling the average steric hindrance of the mixed solvent. Experimental and theoretical results show that for two homologous solvents, although the number of donors is similar, the molecular volume difference is large, but the difference in steric hindrance is significantly changed. At present, there are several problems in the optimization of perovskite single crystals: 1. The grown perovskite single crystals have poor performance, which is specifically manifested in defect density, rocking curve, etc.; 2. The existing inversion crystallization method uses a single, usually toxic solvent with appropriate polarity and Lewis basicity, so the growth conditions are limited to a narrow window, which hinders further optimization of crystal quality.

[0004] Therefore, it is very necessary to develop a new method for growing ultra-low defect perovskite single crystals. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a preparation method for growing ultra-low defect perovskite single crystals based on steric control; a precursor is dissolved in a solvent by an inversion crystallization method, and the temperature is adjusted to grow the single crystal; a perovskite single crystal with an ultra-low defect density is obtained by regulating the solvent ratio and selecting the growth temperature based on steric theory.

[0006] In order to achieve the above objectives, the technical solution of the present invention is: a preparation method for growing ultra-low defect perovskite single crystals based on steric control, comprising the following steps:

[0007] (1) Preparing a perovskite single crystal precursor solution: dissolving a perovskite single crystal precursor in a homogeneous solvent having coordination ability to prepare a precursor solution;

[0008] (2) Generating perovskite single crystal seed crystals: taking the perovskite single crystal precursor solution obtained in step (1), heating it until microcrystals appear, selecting well-formed crystals, drying them, and storing them as seed crystals for future use;

[0009] (3) Growing a perovskite single crystal: placing the perovskite single crystal seed generated in step (2) in the perovskite single crystal precursor solution obtained in step (1) and heating it to grow a perovskite single crystal.

[0010] In a preferred embodiment of the present invention, the homogeneous solvent having coordination ability in step (1) includes but is not limited to at least one of δ-valerolactone (DVL), γ-valerolactone (GVL) and γ-caprolactone (GCL), ethylene carbonate, propylene carbonate, butylene carbonate, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), and N,N-diethylformamide (DEF).

[0011] In a preferred embodiment of the present invention, the perovskite single crystal precursor in step (1) comprises an organic cation halide / metal cation halide AX and a metal halide BX y At least one of .

[0012] Further preferably, A in the organic cation halide / metal cation halide AX includes but is not limited to Cs + 、MA + 、F-PEA + 、PEA + , FA + , GA + At least one of X includes F - , Cl - Br - ,I - At least one of .

[0013] Further preferably, the metal halide BX y B includes but is not limited to Pb 2+ Sn 2+ 、Zn 2+ 、Ag + , Cu 2+ 、Bi 3+ , Sr 2+At least one of X includes F - , Cl - Br - ,I - At least one of , y is 1, 2 or 3, and its value is consistent with the chemical valence state of the metal ion involved in B.

[0014] In a preferred embodiment of the present invention, the concentration of the perovskite single crystal precursor solution in step (1) is 0.5-1.6 mol / L.

[0015] In a preferred embodiment of the present invention, the heating temperature in step (2) is 45-120° C. and the insulation time is 30-60 min.

[0016] In a preferred embodiment of the present invention, the heating temperature of the perovskite single crystal seed in step (3) is 45-120° C., and the holding time is 3-10 h.

[0017] An ultra-low defect perovskite single crystal is prepared by a preparation method for growing an ultra-low defect perovskite single crystal based on steric control.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The inversion crystallization method of the present invention can use green and non-toxic solvents, which is environmentally friendly and will not cause environmental pollution and has no toxic effects on the human body;

[0020] 2. The present invention can achieve the growth of perovskite single crystals with ultra-low defect density and high stability through steric hindrance theory regulation;

[0021] 3. The preparation method based on steric hindrance theory of the present invention is universal and provides reliable theoretical support for future exploration of perovskite single crystal growth in other solvents. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of MAPbI3 single crystals grown in different solvents in Example 1 and the corresponding laser confocal microscopy morphology roughness characterization diagram;

[0023] Figure 2 Example 1MAPbI3-DVL 0.8 GCL 0.2 Dark state current-voltage curve;

[0024] Figure 3 Schematic diagram of MAPbBr3 single crystals grown in different solvents in Example 2 and the corresponding laser confocal microscopy morphology roughness characterization diagram;

[0025] Figure 4 Example 2MAPbBr3-DMF0.8 DEF 0.2 Dark state current-voltage curve;

[0026] Figure 5 PEA grown in different solvents in Example 3 0.35 MA 0.8 PbI 3.15 Schematic diagram of a single crystal and the corresponding laser confocal microscopy morphology and roughness characterization image. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is described in more detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0028] A preparation method for growing ultra-low defect perovskite single crystal based on steric control, comprising the following steps:

[0029] (1) Preparing a perovskite single crystal precursor solution: dissolving a perovskite single crystal precursor in a homogeneous solvent having coordination ability to prepare a precursor solution;

[0030] (2) Generating perovskite single crystal seed crystals: taking the perovskite single crystal precursor solution obtained in step (1), heating it until microcrystals appear, selecting well-formed crystals, drying them, and storing them as seed crystals for future use;

[0031] (3) Growing a perovskite single crystal: placing the perovskite single crystal seed generated in step (2) in the perovskite single crystal precursor solution obtained in step (1) and heating it to grow a perovskite single crystal.

[0032] The homogeneous solvent having coordination ability in step (1) includes but is not limited to at least one of δ-valerolactone (DVL), γ-valerolactone (GVL), γ-caprolactone (GCL), ethylene carbonate, propylene carbonate, butylene carbonate, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), and N,N-diethylformamide (DEF).

[0033] In the step (1), the perovskite single crystal precursor comprises an organic cation halide / metal cation halide AX and a metal halide BX y . Where A includes but is not limited to Cs + 、MA + 、F-PEA + 、PEA + , FA + , GA + At least one of; B includes but is not limited to Pb 2+ Sn 2+ 、Zn 2+ 、Ag+ , Cu 2+ ,Bi 3+ , Sr 2+ At least one of; X includes F - , Cl - Br - ,I - At least one of; y is 1, 2 or 3, and its value is consistent with the chemical valence state of the metal ion involved in B.

[0034] The concentration of the perovskite single crystal precursor solution in step (1) is 0.5-1.6 mol / L.

[0035] In the step (2), the heating temperature is 45-120° C. and the insulation time is 30-60 min.

[0036] In the step (3), the heating temperature of the perovskite single crystal seed is 45-120° C., and the insulation time is 3-10 hours.

[0037] An ultra-low defect perovskite single crystal is prepared by a preparation method for growing an ultra-low defect perovskite single crystal based on steric control.

[0038] Example 1

[0039] A method for growing a three-dimensional MAPbI3 single crystal with ultra-low defect density based on steric control is prepared by the following preparation method, comprising the following steps:

[0040] (1) Preparation of MAPbI3 single crystal precursor solution: δ-valerolactone (DVL) and γ-caprolactone (GCL) were mixed at volume ratios of 10:0, 8:2, 5:5, 2:8 and 0:10 to obtain mixed solvents with different volume ratios; MAI and PbI2 were added to the mixed solvents with different volume ratios, and then ultrasonically dissolved, wherein the molar ratio of MAI to PbI2 was 1.1:1, and the concentrations of PbI2 in the mixed solvents were 1.6 mol / L, 1.5 mol / L, 1.25 mol / L, 1 mol / L and 0.63 mol / L, respectively; wherein excess MAI was helpful to complete the conversion of PbI2 to MAPbI3; after ultrasonically dissolving for 1 hour, a MAPbI3 single crystal precursor solution was obtained;

[0041] (2) Generate MAPbI3 single crystal seed: Take 0.5mL of the MAPbI3 single crystal precursor solution obtained in step (1) and heat it on hot plates at 115°C, 80°C, 70°C, 65°C, and 45°C for 30 minutes respectively; grow tiny single crystals, and select tiny single crystals with good morphology as seeds for use. Subsequently, filter 2ml of the MAPbI3 single crystal precursor solution obtained in step (1) through a 0.22μm nylon filter to ensure the cleanliness of the solution and avoid the influence of dust and small particles on the crystallization process. The filtered solution will be used to initialize the seed growth of the inversion crystallization method;

[0042] (3) Growth of MAPbI3 single crystals: The MAPbI3 single crystal seed generated in step (2) was transferred to the corresponding filtered MAPbI3 single crystal precursor solution, and placed on a hot heating plate for growth at 115°C, 80°C, 70°C, 65°C, and 45°C, respectively. The growth was maintained for 6 h to obtain MAPbI3 single crystals. Finally, the grown crystals were washed with acetone and vacuum dried for 2 h.

[0043] Schematic diagram of MAPbI3 single crystal grown by the above-mentioned mixed solvent inversion crystallization method with different volume ratios is shown in Figure 1 As shown, from Figure 1 It can be seen that by controlling the ratio of solvents with different steric hindrances, the growth of MAPbI3 single crystals can be achieved in a wide temperature range. 0.8 GCL 0.2 The crystals grown in the medium have larger sizes.

[0044] like Figure 2 MAPbI3-DVL shown 0.8 GCL 0.2 The dark state current-voltage curves of our perovskite single crystals are regulated by steric engineering and have an ultra-low defect density as calculated.

[0045] Example 2

[0046] A method for growing an ultra-low defect density three-dimensional MAPbBr3 single crystal based on steric control is prepared by the following preparation method, comprising the following steps:

[0047] (1) Preparation of MAPbBr3 single crystal precursor solution: N,N dimethylformamide (DMF) and N,N diethylformamide (DEF) were mixed together in volume ratios of 10:0, 8:2, 6:4, 4:6, 2:8, and 0:10 to obtain mixed solvents of different volume ratios; MABr and PbBr2 were added to the mixed solvents of different volume ratios, and then ultrasonically dissolved, wherein the molar ratio of MABr to PbBr2 was 1.1:1; the concentrations of PbBr2 in the mixed solvents were 1.25 mol / L, 1.25 mol / L, 0.6 mol / L, 0.55 mol / L, 0.35 mol / L, and 0.13 mol / L, respectively. Excessive MABr helps to complete the conversion of PbBr2 to MAPbBr3; after ultrasonic dissolution for 1 hour, a MAPbBr3 single crystal precursor solution was obtained;

[0048] (2) Generate MAPbBr3 single crystal seed: Take 0.5mL of the MAPbBr3 single crystal precursor solution obtained in step (1) and heat it on hot plates at 80℃, 70℃, 60℃, 55℃, 45℃, and 40℃ for 30min respectively; grow tiny single crystals, and select tiny single crystals with good morphology as seeds for standby use. Subsequently, filter 2ml of MAPbBr3 single crystal precursor solution through a 0.22μm nylon filter to ensure the cleanliness of the solution and avoid the influence of dust and small particles on the crystallization process. The filtered solution will be used to initialize the seed growth of the inversion crystallization method;

[0049] (3) Growth of MAPbBr3 single crystals: The MAPbBr3 single crystal seed generated in step (2) was transferred to the corresponding filtered MAPbBr3 single crystal precursor solution, and placed on a hot heating plate, and grown at 80°C, 70°C, 60°C, 55°C, 45°C, and 40°C, respectively. The growth was maintained for 6 hours to obtain MAPbBr3 single crystals. Finally, the grown crystals were washed with acetone and vacuum dried for 2 hours.

[0050] The schematic diagram of the MAPbBr3 single crystal grown by the mixed solvent inversion crystallization method with different volume ratios is shown in Figure 3 As shown, from Figure 3 It can be seen that by controlling the ratio of solvents with different steric hindrances, the growth of MAPbI3 single crystals can be achieved in a wide temperature range. 0.8 GCL 0.2 The crystals grown in the medium have larger sizes.

[0051] like Figure 4 MAPbBr3-DMF shown 0.8 DEF 0.2 The dark state current-voltage curves of our perovskite single crystals are regulated by steric engineering and have an ultra-low defect density as calculated.

[0052] Example 3

[0053] A quasi-two-dimensional PEA with ultra-low defect density grown based on steric control 0.35 MA 0.8 PbI 3.15 The single crystal is prepared by the following preparation method, comprising the following steps:

[0054] (1) Preparation of PEA 0.35 MA 0.8 PbI 3.15 Single crystal precursor solution: δ-valerolactone (DVL) and γ-caprolactone (GCL) were mixed together in volume ratios of 10:0, 8:2, 7:3, 6:4, and 5:5 to obtain mixed solvents with different volume ratios; PEAI, MAI, and PbI2 were added to the mixed solvents with different volume ratios, and then ultrasonically dissolved, wherein the molar ratio of PEAI, MAI, and PbI2 was 0.44:1.32:1.6; the concentration of PbI2 in the mixed solvent was 1.6 mol / L, wherein the excess PEAI and MAI were helpful to complete the conversion of PbI2 to PEA 0.35 MA 0.8 PbI 3.15 After ultrasonic dissolution for 1 h, PEA was obtained. 0.35 MA 0.8 PbI 3.15 Single crystal precursor solution;

[0055] (2) Generate PEA 0.35 MA 0.8 PbI 3.15 Single crystal seed: Take 0.5 mL of the MAPbBr3 single crystal precursor solution prepared in step (1) and heat it on a hot plate at 140°C, 125°C, 105°C, 90°C, and 80°C for 30 min respectively; grow tiny single crystals, and select tiny single crystals with good morphology as seed crystals for later use. Then, add 2 ml of PEA 0.35 MA 0.8 PbI 3.15 The single crystal precursor solution is filtered through a 0.22 μm nylon filter to ensure the cleanliness of the solution and avoid the influence of dust and small particles on the crystallization process. The filtered solution will be used to initialize the seed growth of the inversion crystallization method;

[0056] (3) Growth of PEA 0.35 MA 0.8 PbI 3.15 Single crystal: PEA generated in step (2) 0.35 MA 0.8 PbI 3.15 Transfer the single crystal seed to the corresponding filtered PEA 0.35 MA0.8 PbI 3.15 The single crystal precursor solution was placed on a hot heating plate and grown at 140°C, 125°C, 105°C, 90°C, and 80°C, respectively, and kept warm for 6 hours to obtain PEA. 0.35 MA 0.8 PbI 3.15 Single crystal, finally wash the grown crystal with acetone and dry in vacuum for 2h.

[0057] The PEA grown by the mixed solvent inversion crystallization method with different volume ratios 0.35 MA 0.8 PbI 3.15 Schematic diagram of a single crystal Figure 5 As shown, from Figure 5 It can be seen that by controlling the ratio of solvents with different steric hindrances, PEA can be achieved in a wide temperature range. 0.35 MA 0.8 PbI 3.15 Single crystal growth, solvent DVL 0.6 GCL 0.4 The crystals grown in the medium have larger sizes.

[0058] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for growing ultra-low defect perovskite single crystals based on steric control, characterized in that: The steps include: (1) Preparing a perovskite single crystal precursor solution: dissolving a perovskite single crystal precursor in a homogeneous solvent having coordination ability to prepare a precursor solution; (2) Generating perovskite single crystal seed crystals: taking the perovskite single crystal precursor solution obtained in step (1), heating it until microcrystals appear, selecting well-formed crystals, drying them, and storing them as seed crystals for future use; (3) Growing a perovskite single crystal: placing the perovskite single crystal seed generated in step (2) in the perovskite single crystal precursor solution obtained in step (1) and heating it to grow a perovskite single crystal.

2. The method for preparing ultra-low defect perovskite single crystal based on steric control growth according to claim 1, characterized in that: The homogeneous solvent having coordination ability in step (1) includes but is not limited to at least one of δ-valerolactone, γ-valerolactone and γ-caprolactone, ethylene carbonate, propylene carbonate, butylene carbonate, N,N-dimethylformamide, N,N-dimethylacetamide and N,N-diethylformamide.

3. The method for preparing ultra-low defect perovskite single crystal based on steric control growth according to claim 1, characterized in that: In the step (1), the perovskite single crystal precursor comprises an organic cation halide / metal cation halide AX and a metal halide BX y At least one of .

4. The method for preparing ultra-low defect perovskite single crystal based on steric control growth according to claim 3, characterized in that: A in the organic cation halide / metal cation halide AX includes but is not limited to Cs + 、MA + 、F-PEA + 、PEA + , FA + , GA + At least one of X includes F - , Cl - Br - ,I - At least one of .

5. The method for preparing ultra-low defect perovskite single crystal based on steric control growth according to claim 3, characterized in that: The metal halide BX y B includes but is not limited to Pb 2+ Sn 2+ 、Zn 2+ 、Ag + , Cu 2+ 、Bi 3+ , Sr 2+ At least one of X includes F - , Cl - Br - ,I - At least one of , y is 1, 2 or 3, and its value is consistent with the chemical valence state of the metal ion involved in B.

6. The method for preparing ultra-low defect perovskite single crystal based on steric control growth according to claim 1, characterized in that: The concentration of the perovskite single crystal precursor solution in step (1) is 0.5-1.6 mol / L.

7. The method for preparing ultra-low defect perovskite single crystal based on steric control growth according to claim 1, characterized in that: In the step (2), the heating temperature is 45-120° C. and the insulation time is 30-60 min.

8. The method for preparing ultra-low defect perovskite single crystal based on steric control growth according to claim 1, characterized in that: In the step (3), the heating temperature of the perovskite single crystal seed is 45-120° C., and the insulation time is 3-10 hours.

9. An ultra-low defect perovskite single crystal obtained by the preparation method for growing an ultra-low defect perovskite single crystal based on steric control as described in any one of claims 1 to 8.

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