A high-resistivity CsPbBr3 perovskite single crystal, its growth method and application

Abstract

This invention belongs to the field of semiconductor high-energy radiation detection technology, specifically a high-resistivity CsPbBr3 perovskite single crystal, its growth method, and its applications. The method includes: preparing a precursor solution by dissolving CsBr and PbBr2 in DMSO; adjusting the growth kinetics at the solution interface by adding a growth regulator to obtain a clear and homogeneous precursor solution under isothermal conditions; filtering the solution through micropores and inducing crystal nucleation by slow heating, then employing a seed-guided isothermal growth strategy to achieve controllable growth of the CsPbBr3 single crystal under near-thermodynamic equilibrium conditions. This invention improves the structural order and lattice integrity of the CsPbBr3 perovskite single crystal by reducing the kinetic rate at the crystal growth interface, thereby reducing the density of defect states within the crystal and improving the electrical stability of the single crystal material under high electric field conditions. The energy spectral resolution of γ-rays in the Bi / CsPbBr3 / Au device constructed based on the prepared single crystal is thus improved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor high-energy radiation detection technology, specifically relating to high-resistivity CsPbBr3 perovskite single crystals, their growth methods, and applications. Background Technology

[0002] Halide perovskite materials, due to their high atomic number, excellent carrier transport properties, and solution-soluble preparation capabilities, have shown promising application prospects in high-energy radiation detection. In existing technologies, CsPbBr3 perovskite single crystals are typically grown using reverse temperature crystallization, solvent evaporation, or gradient cooling methods. However, these methods often operate under conditions deviating from thermodynamic equilibrium, resulting in rapid interfacial kinetics during crystal growth and a tendency to introduce structural defects such as dislocations, vacancies, and antisites within the crystal. Furthermore, under high electric fields or prolonged bias conditions, ion migration easily occurs in CsPbBr3 perovskite single crystals, leading to device performance degradation, signal drift, and decreased stability, thus limiting their practical application in high-bias, high-resolution radiation detection. Therefore, there is an urgent need to propose a method for controllable growth of CsPbBr3 perovskite single crystals under near-thermodynamic equilibrium conditions to reduce the interfacial kinetics during crystal growth, improve crystal structural order and electrical stability, and thus meet the requirements of high-energy radiation detection for material stability and reliability. Summary of the Invention

[0003] To address the common problems in existing CsPbBr3 perovskite single crystal growth methods, such as high growth interface kinetic rates, high crystal defect density, and susceptibility to ion migration and insufficient device stability under high electric fields, this invention aims to provide a near-thermodynamic equilibrium growth method for CsPbBr3 perovskite single crystals. By controlling the solution composition and temperature conditions during crystal growth, the kinetic rate at the crystal growth interface is reduced, enabling controllable growth of CsPbBr3 perovskite single crystals under near-thermodynamic equilibrium conditions. This improves the structural order, electrical properties, and bias voltage stability of the single crystal material, meeting the application requirements for material stability and reliability in the field of high-energy radiation detection.

[0004] This invention first provides a near-thermodynamic equilibrium growth method for CsPbBr3 perovskite single crystals, the specific steps of which are as follows:

[0005] (1) CsBr and PbBr2 were dissolved in DMSO solvent in stoichiometric ratio to obtain a precursor solution;

[0006] (2) Add a growth regulator to the precursor solution and mix it thoroughly by stirring at a constant temperature to obtain a clear and homogeneous precursor solution;

[0007] (3) The precursor solution is filtered to remove insoluble impurities;

[0008] (4) The filtered precursor solution was slowly heated under controlled heating to induce nucleation, and the supernatant was separated after the formation of crystal nuclei.

[0009] (5) Place the seed crystal in the supernatant and maintain crystal growth under constant temperature conditions to slow down the kinetic rate of the crystal growth interface and obtain high-quality CsPbBr3 perovskite single crystal under near thermodynamic equilibrium conditions.

[0010] Furthermore:

[0011] In step (1), the molar ratio of CsBr to PbBr2 is 1:(1.5-2), preferably 1:2.

[0012] In step (2), the growth regulator is selected from one or more of organic ammonium salts, quaternary ammonium salts, or surfactants. Preferably, it is hexadecyltrimethylammonium bromide, tetramethylammonium bromide, tetrabutylammonium bromide, choline bromide, acetylcholine bromide, and acetyl-β-methylcholine bromide or their equimolar substitutes.

[0013] The temperature for constant temperature stirring is 60–80 °C, and the time is 4–16 h.

[0014] In step (3), a microporous filter membrane with a pore size of 0.22 μm is used for filtration.

[0015] In step (4), the heating rate of the slow heating is 0.5–3 °C / day.

[0016] In step (5), the seed crystal is a CsPbBr3 perovskite single crystal with a size of less than 1 mm.

[0017] The CsPbBr3 single crystal prepared by this invention can effectively suppress thermally activated conductivity and trap-assisted conductivity channels, exhibiting a high bulk resistivity. This allows it to weaken ion migration behavior and improve the electrical stability of the material under high electric field and long-term bias conditions.

[0018] The CsPbBr3 single crystal prepared by this invention can be used to prepare a γ-ray energy spectrum detector. The specific steps are as follows:

[0019] (1) Polish CsPbBr3 perovskite single crystal to serve as a CsPbBr3 perovskite single crystal layer for absorbing γ-rays.

[0020] (2) A low work function metal is deposited on one side of the CsPbBr3 perovskite single crystal layer by vacuum evaporation as a metal anode to form a Schottky contact with the single crystal;

[0021] (3) On the other side of the perovskite crystal, a metal with a high work function is selected, and a metal cathode is prepared by vacuum evaporation.

[0022] (4) The metal cathode is connected to the PCB board using carbon glue, and the metal anode is connected to the PCB board through wires to prepare a CsPbBr3 single crystal-based γ-ray energy spectrum detector.

[0023] Furthermore:

[0024] In step (1), the CsPbBr3 perovskite single crystal is polished step by step using SiC sandpaper of different grit sizes, in the order of 3000#, 5000#, 7000# and 10000#, to make the surface of the perovskite crystal smooth; then the CsPbBr3 single crystal is polished on a polishing cloth using MgO powder with a particle size of 50nm as the abrasive until the surface of the CsPbBr3 single crystal is bright and free of scratches.

[0025] The polished CsPbBr3 single crystals were immersed in cyclohexane to clean the residual MgO powder on the surface; then placed in an ultraviolet ozone generator for 3-10 minutes to clean the organic matter adhering to the crystal surface.

[0026] In step (2), the low work function metal is selected from: bismuth (Bi), indium (In), tin (Sn), and aluminum (Al);

[0027] When depositing metal electrodes by vapor deposition, the gas pressure inside the vapor deposition chamber shall not exceed 5 × 10⁻⁶. -4 Pa, evaporation rate is 0.01-0.3 Å s -1 The thickness of the metal electrode is 50-100 nm.

[0028] In step (3), the high work function metal is selected from gold (Au).

[0029] When depositing metal electrodes by vapor deposition, the gas pressure inside the vapor deposition chamber shall not exceed 5 × 10⁻⁶. -4 Pa, evaporation rate is 0.01-0.3 Å s -1 The thickness of the metal electrode is 50-100 nm.

[0030] The advantages of this invention compared to the prior art are as follows:

[0031] (1) By controlling the growth process of CsPbBr3 single crystal under near thermodynamic equilibrium conditions, the present invention slows down the dynamic rate of the crystal growth interface, which is conducive to the orderly arrangement of the crystal structure and can effectively reduce the formation of sub-bandgap defect states and structural defects inside the crystal, thereby reducing the trapping probability of photogenerated carriers and providing more favorable material conditions for the effective transport of carriers.

[0032] (2) Due to the reduction of the defect state density inside the crystal, the CsPbBr3 single crystal prepared by the present invention can effectively suppress thermally activated conductivity and trap-assisted conductivity channels, exhibiting a high bulk resistivity, thereby weakening ion migration behavior and improving the electrical stability of the material under high electric field and long-term bias conditions.

[0033] (3) Based on the above improvements in structure and electrical properties, the CsPbBr3 single crystal prepared by this invention is suitable for constructing high-resolution γ-ray detectors, which is beneficial to improving the signal stability and reliability of the device under long-term working conditions.

[0034] (4) The method described in this invention has a simple process flow, controllable conditions, and good repeatability. It is suitable for laboratory preparation and has the potential for further scale-up preparation and device integration applications. Attached Figure Description

[0035] Figure 1 The structural diagram shows the fabrication of a vertical Schottky structure gamma-ray detector.

[0036] Figure 2 This is a photograph of a CsPbBr3 single crystal grown using a near-thermodynamic equilibrium growth method in this invention.

[0037] Figure 3 The resistivity is that of CsPbBr3 single crystals grown using a near-thermodynamic equilibrium growth method.

[0038] Figure 4 It is the effect of near-thermodynamic equilibrium growth method before and after 241 Energy-resolved spectrum at Am@59.5keV.

[0039] The labels in the figure are: 1 is the gold electrode layer; 2 is the CsPbBr3 single crystal layer; 3 is the bismuth electrode layer. Detailed Implementation

[0040] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0041] Example 1: Fabrication of CsPbBr3 and a γ-ray detector, the specific steps are as follows:

[0042] 1. Preparation of CsPbBr3 precursor solution: 4.5 mmol of CsBr and 9 mmol of PbBr2 were dissolved in 5 mL of DMSO solvent at a stoichiometric ratio of 1:2 to prepare a precursor solution (without adding organic ligand additives); the solution was stirred at 70 °C for 8 h to ensure thorough mixing, resulting in a clear and homogeneous precursor solution; the precursor solution was filtered through an organic filter with a pore diameter of 0.22 μm to remove insoluble impurities.

[0043] 2. CsPbBr3 seed crystal growth: The filtered precursor solution was placed in a sealed container and heated from 70℃ to 80℃ at a slow heating rate of 2℃ / day to induce crystal nucleation.

[0044] 3. CsPbBr3 single crystal growth: The supernatant was placed in a container, and then seed crystals with a size of less than 1 mm were placed in the solution. The crystal growth was maintained at a constant temperature of 80℃ to slow down the kinetic rate of the crystal growth interface. CsPbBr3 perovskite single crystals were obtained under near thermodynamic equilibrium conditions.

[0045] 4. CsPbBr3 Single Crystal Polishing: The CsPbBr3 perovskite single crystal is progressively polished using SiC abrasive paper of different grit sizes, in the order of 3000#, 5000#, 7000#, and 10000#, to make the perovskite crystal surface smooth. Then, the CsPbBr3 single crystal is polished on a polishing cloth using MgO powder with a particle size of 50nm as the abrasive until the surface of the CsPbBr3 single crystal is bright and free of scratches. After polishing, the CsPbBr3 single crystal is immersed in cyclohexane to clean the residual MgO powder on the surface, and then placed in an ultraviolet ozone generator for 3-10 minutes to clean the organic matter attached to the crystal surface.

[0046] 5. Fabrication of CsPbBr3 single crystal devices: Vacuum evaporation was employed using a circular mask with a diameter of 3 mm. The vacuum level was maintained at 5 × 10⁻⁶ during evaporation. -4 Below Pa, the evaporation rate is 0.01 Å s. -1 The thickness is 50 nm. High work function gold is deposited on one side of a CsPbBr3 perovskite single crystal to form an ohmic contact with the CsPbBr3 single crystal. Low work function bismuth is deposited on the other side of the CsPbBr3 single crystal to form a Schottky contact with the CsPbBr3 single crystal. The gold electrode is connected to a PCB board using carbon paste, and the bismuth electrode is connected to the PCB board via wires, thus fabricating a vertical Schottky structure gamma-ray detector.

[0047] Example 2: Fabrication of CsPbBr3 and a γ-ray detector, the specific steps are as follows:

[0048] 1. Preparation of CsPbBr3 precursor solution: 4.5 mmol of CsBr and 9 mmol of PbBr2 were dissolved in 5 mL of DMSO solvent at a stoichiometric ratio of 1:2 to prepare a precursor solution; then 0.5 mmol of acetylcholine bromide additive was added to the precursor solution, and the mixture was stirred at 70 °C for 8 h to ensure thorough mixing, resulting in a clear and homogeneous precursor solution; the precursor solution was filtered through an organic filter with a pore diameter of 0.22 μm to remove insoluble impurities;

[0049] 2. CsPbBr3 seed crystal growth: The filtered precursor solution was placed in a sealed container and heated from 70℃ to 80℃ at a slow heating rate of 2℃ / day to induce crystal nucleation.

[0050] 3. CsPbBr3 single crystal growth: The supernatant was placed in a container, and then seed crystals with a size of less than 1 mm were placed in the solution. The crystal growth was maintained at a constant temperature of 80℃ to slow down the kinetic rate of the crystal growth interface. CsPbBr3 perovskite single crystals were obtained under near thermodynamic equilibrium conditions.

[0051] 4. CsPbBr3 Single Crystal Polishing: The CsPbBr3 perovskite single crystal is progressively polished using SiC abrasive paper of different grit sizes, in the order of 3000#, 5000#, 7000#, and 10000#, to make the perovskite crystal surface smooth. Then, the CsPbBr3 single crystal is polished on a polishing cloth using MgO powder with a particle size of 50nm as the abrasive until the surface of the CsPbBr3 single crystal is bright and free of scratches. After polishing, the CsPbBr3 single crystal is immersed in cyclohexane to clean the residual MgO powder on the surface, and then placed in an ultraviolet ozone generator for 3-10 minutes to clean the organic matter attached to the crystal surface.

[0052] 5. Fabrication of CsPbBr3 single crystal devices: Vacuum evaporation was employed using a circular mask with a diameter of 3 mm. The vacuum level was maintained at 5 × 10⁻⁶ during evaporation. -4 Below Pa, the evaporation rate is 0.01 Å s. -1 The thickness is 50 nm. High work function gold is deposited on one side of a CsPbBr3 perovskite single crystal to form an ohmic contact with the CsPbBr3 single crystal. Low work function bismuth is deposited on the other side of the CsPbBr3 single crystal to form a Schottky contact with the CsPbBr3 single crystal. The gold electrode is connected to a PCB board using carbon paste, and the bismuth electrode is connected to the PCB board via wires, thus fabricating a vertical Schottky structure gamma-ray detector.

[0053] Example 3: Resistivity and gamma-ray energy spectrum resolution of CsPbBr3 single crystal, the specific steps are as follows:

[0054] 1. Fabrication of CsPbBr3 single-crystal resistivity testing devices: Metal electrodes were deposited onto the CsPbBr3 single crystals grown in Examples 1 and 2 using vacuum evaporation to obtain Au / CsPbBr3 / Au devices. A circular mask with a diameter of 3 mm was used, and the vacuum level was maintained at 5 × 10⁻⁶ during evaporation. -4 Below Pa, the evaporation rate is 0.01 Å s. -1The thickness is 50 nm. High work function metallic gold is deposited on one side of the CsPbBr3 perovskite single crystal to form an ohmic contact with the CsPbBr3 single crystal. High work function metallic gold is also deposited on the other side of the CsPbBr3 single crystal to form an ohmic contact with the CsPbBr3 single crystal. Carbon paste is used to connect the gold electrodes to the PCB board, and the gold electrodes on the other side are connected to the PCB board via wires for subsequent testing.

[0055] 2. Fabrication of CsPbBr3 single-crystal γ-ray detector devices: Metal electrodes were deposited on the CsPbBr3 single crystals grown in Examples 1 and 2 using vacuum evaporation to obtain Bi / CsPbBr3 / Au devices. A circular mask with a diameter of 3 mm was used, and the vacuum level was maintained at 5 × 10⁻⁶ during evaporation. -4 Below Pa, the evaporation rate is 0.01 Å s. -1 The thickness is 50 nm. High work function gold is deposited on one side of a CsPbBr3 perovskite single crystal to form an ohmic contact with the CsPbBr3 single crystal. Low work function bismuth is deposited on the other side of the CsPbBr3 single crystal to form a Schottky contact with the CsPbBr3 single crystal. The gold electrode is connected to a PCB board using carbon paste, and the bismuth electrode is connected to the PCB board via wires, thus fabricating a vertical Schottky structure gamma-ray detector.

[0056] 3. Dark-state current-voltage curves were tested on the Au / CsPbBr3 / Au device obtained in step 1 of Example 3, and the resistivity of the single crystal obtained in Example 1 and Example 2 was compared. Figure 3 It can be seen that the resistivity of the single crystal obtained in Example 2 using acetylcholine bromide as a ligand reached the order of 10, which is better than the resistivity of the single crystal in Example 1.

[0057] 4. Perform γ-ray spectroscopy on the Bi / CsPbBr3 / Au device obtained in step 2, and compare the spectral resolution of the single crystals obtained in Example 1 and Example 2. When the device operates under reverse bias conditions, 241 The Am radioactive source enters from the anode of the detector, and is then... Figure 4 It can be seen that the Bi / CsPbBr3 / Au devices prepared using ligand-grown single crystals have higher channel addresses and smaller full width at half maximum (FWHM) peaks, which is beneficial for... 241 The energy resolution of the Am@59.5keV emission reached 11.12%.

[0058] The above description is merely a specific embodiment of the present invention; the scope of protection of the present invention is not limited thereto. Any person with knowledge in the art can discover and implement equivalent modifications or substitutions within the technical scope disclosed in the present invention, and all such modifications or substitutions should be included within the scope of protection of the present invention.

Claims

1. A near-thermodynamic equilibrium growth method for CsPbBr3 perovskite single crystals, characterized in that, The specific steps are as follows: (1) CsBr and PbBr2 were dissolved in DMSO solvent in stoichiometric ratio to obtain a precursor solution; (2) Add a growth regulator to the precursor solution and mix it thoroughly by stirring at a constant temperature to obtain a clear and homogeneous precursor solution; (3) The precursor solution is filtered to remove insoluble impurities; (4) The filtered precursor solution was slowly heated under controlled heating to induce nucleation, and the supernatant was separated after the formation of crystal nuclei. (5) Place the seed crystal in the supernatant and maintain crystal growth under constant temperature conditions to slow down the kinetic rate of the crystal growth interface and obtain high-quality CsPbBr3 perovskite single crystal under near thermodynamic equilibrium conditions.

2. The method according to claim 1, characterized in that, The molar ratio of CsBr to PbBr2 in step (1) is 1:(1.5-2).

3. The method according to claim 1, characterized in that, The growth regulator in step (2) is selected from one or more of organic ammonium salts, quaternary ammonium salts or surfactants; the constant temperature stirring temperature is 60–80 ℃ and the time is 4–16 h.

4. The method according to claim 1, characterized in that, In step (3), a microporous membrane with a pore size of 0.22 μm is used for filtration.

5. The method according to claim 1, characterized in that, The heating rate described in step (4) is 0.5–3 °C / day.

6. The method according to claim 1, characterized in that, The seed crystal mentioned in step (5) is a CsPbBr3 perovskite single crystal with a size of less than 1 mm.

7. A CsPbBr3 perovskite single crystal obtained by the method described in any one of claims 1-6.

8. The application of the CsPbBr3 perovskite single crystal as described in claim 7 in the preparation of a gamma-ray energy spectrum detector, characterized in that, The specific steps are as follows: (1) Polish CsPbBr3 perovskite single crystal to serve as a CsPbBr3 perovskite single crystal layer for absorbing γ-rays. (2) A low work function metal is deposited on one side of the CsPbBr3 perovskite single crystal layer by vacuum evaporation as a metal anode to form a Schottky contact with the single crystal; (3) On the other side of the perovskite crystal, a metal with a high work function is selected, and a metal cathode is prepared by vacuum evaporation. (4) The metal cathode is connected to the PCB board using carbon glue, and the metal anode is connected to the PCB board through wires to prepare a CsPbBr3 single crystal-based γ-ray energy spectrum detector.

9. The application according to claim 8, characterized in that: In step (1), the CsPbBr3 perovskite single crystal is gradually polished using SiC sandpaper of different particle sizes to make the surface of the CsPbBr3 perovskite crystal smooth; then the CsPbBr3 single crystal is polished on a polishing cloth using MgO powder with a particle size of 50nm as the abrasive until the surface of the CsPbBr3 single crystal is bright and free of scratches. The polished CsPbBr3 single crystals were immersed in cyclohexane to clean the residual MgO powder on the surface; then placed in an ultraviolet ozone generator for 3-10 minutes to clean the organic matter adhering to the crystal surface. In step (2), the low work function metal is selected from: bismuth (Bi), indium (In), tin (Sn), and aluminum (Al); When depositing metal electrodes by vapor deposition, the gas pressure inside the vapor deposition chamber shall not exceed 5 × 10⁻⁶. -4 Pa, evaporation rate is 0.01-0.3 Å s -1 The thickness of the metal electrode is 50-100 nm; In step (3), the high work function metal is selected from gold (Au). When depositing metal electrodes by vapor deposition, the gas pressure inside the vapor deposition chamber shall not exceed 5 × 10⁻⁶. -4 Pa, evaporation rate is 0.01-0.3 Å s -1 The thickness of the metal electrode is 50-100 nm.

10. A gamma-ray energy spectrum detector, wherein the CsPbBr3 perovskite single crystal as described in claim 7 is used as the CsPbBr3 perovskite single crystal layer for absorbing gamma rays.

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