Perovskite single crystal tempering treatment method capable of improving domain scale uniformity

Abstract

The invention provides a tempering treatment method and device for perovskite single crystals capable of improving domain scale uniformity, belongs to the technical field of perovskite radiation detectors, and aims at solving the problem that in the crystal growth process, the domain scale uniformity is not improved. The problem of the generation of randomly oriented ferroelastic domains due to the physical obstruction of the hard substrate and the stress generated by lattice mismatch between the single crystal and the substrate is solved. According to the method, the temperature gradient field is introduced to the surface of the single crystal, the domain wall is driven to be eliminated in the slow moving process of the temperature gradient field by utilizing the micro stress generated by phase change, the homogeneity of the ferroelastic domain scale of the large-area perovskite single crystal is realized, and meanwhile, the method is compatible with perovskite single crystals with different sizes and magnitudes. The ferroelastic domain in the perovskite single crystal obtained by the method is highly ordered, and compared with a sample which is not treated by the method, the perovskite single crystal has lower defect density, stronger fluorescence intensity, higher crystallization quality and more excellent carrier transport property, and can be used for preparing a radiation detector with more excellent performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of perovskite radiation detectors, and in particular relates to a perovskite crystal, a preparation method thereof and a high-energy radiation ray detector. Background Art

[0002] Radiation detection plays an important role in medical diagnosis and imaging, homeland security, environmental investigation, and basic scientific research. Unlike the traditional charge-integrating signal acquisition mode, photon counting radiation detectors operate in a pulse mode where the radiation field is weak. The detector needs to perform event-by-event analysis and simultaneously identify the intensity and energy of the incident photons. Radiation detectors are mainly used in the testing of gamma-ray energy spectra, where high energy resolution (ER) is a necessary condition for distinguishing gamma-ray photons with different energies. Commercially viable semiconductors for gamma-ray detection include high-purity germanium (HPGe) and CdTe-based semiconductors. However, due to the small band gap of Ge, HPGe can only work at low temperatures. Currently, zinc alloy cadmium telluride (CZT) single crystals can obtain good ER at room temperature, but the high cost of crystal manufacturing process limits large-scale production.

[0003] In recent years, metal halide perovskite (MHP) materials have shown great potential for room-temperature detection due to their excellent physical and optoelectronic properties, including ideal band gap, high average atomic number, large resistivity, balanced electron and hole mobility, large mobility and lifetime (μτ) product, impressive defect tolerance, and low-cost solution preparation. It is worth noting that MAPbI3 (where MA stands for methylammonium) single crystals have three types, namely orthorhombic, tetragonal and cubic structures, and the orthorhombic-tetragonal and tetragonal-cubic transitions occur at 162.2 K and 327.4 K, respectively. The drastic change in temperature can generate stress / strain that is harmful to optoelectronic devices. In addition, during the crystal growth process, the stress generated by the physical hindrance of the hard substrate and the lattice mismatch between the single crystal and the substrate can also induce the generation of randomly oriented ferroelastic domains. Therefore, the preparation of high-performance radiation detectors still depends largely on the careful selection of crystals, which largely limits the yield of detector-grade perovskite single crystal wafers. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of perovskite single crystal growth in the prior art, and a method for preparing perovskite single crystals with uniform domain scale is provided. The device and method can prepare wafer-level perovskite single crystals with large-area internal ferroelastic domains and highly ordered. The prepared perovskite single crystals can be used in high-energy radiation detectors with excellent energy resolution.

[0005] The technical solution adopted by the present invention is as follows: A tempering treatment method for a perovskite single crystal capable of improving the uniformity of domain scale, the method is based on a tempering treatment device for a perovskite single crystal capable of improving the uniformity of domain scale, the device comprising: a sealed box, a heating unit 1, a lifting platform 6 and a heating unit controller; The heating unit controller is connected to the heating unit 1; the lifting platform 6 is arranged at the bottom of the closed box, and a working platform for placing the substrate is installed on the upper part; the closed box has two air holes on the shell, which are used to allow the internal gas to enter and exhaust respectively; the heating unit 1 is used to form a temperature field with a temperature gradient on both sides of the heating area; in addition, the heating unit 1 is movably arranged in the closed box.

[0006] The specific steps of this method are: 1) Prepare a perovskite single crystal, and after polishing to remove impurities, obtain a perovskite single crystal with a smooth surface; 2) Nitrogen is introduced through two air holes on the sealed box, and air is discharged from the other air hole to form a protective atmosphere in the sealed box; 3) placing the perovskite single crystal obtained in step 1) on the working platform, and adjusting the height of the lifting platform 6 so that the perovskite single crystal is close to the heating unit 1; 4) Adjust the heating unit controller to control the heating unit 1 to heat up to 0.1~20K above the tetragonal-cubic phase transition temperature, and form a temperature gradient field on both sides of the area heated by the heating unit 1; the central temperature of the temperature gradient field is above the tetragonal-cubic phase transition temperature, and there is a 5~35 K cm difference between the central temperature and the surrounding area. -1 The temperature gradient; 5) Heating unit 1 heats the perovskite single crystal at a speed of 10-2000 μm s -1 The temperature gradient field is swept across the perovskite single crystal at the same speed to complete the tempering treatment.

[0007] Wherein, the preparation method of the perovskite single crystal in step 1) is selected from: a cooling growth method, a reverse temperature growth method, a Bridgman crystal growth method, a solvent diffusion growth method, a solvent evaporation growth method and a derivative growth method thereof.

[0008] The perovskite single crystal is a three-dimensional perovskite, a two-dimensional perovskite, a two-dimensional and three-dimensional mixed perovskite, a zero-dimensional perovskite or a double perovskite crystal; The molecular formula of the three-dimensional perovskite is ABX3, and the molecular formula of the two-dimensional perovskite or the two-dimensional and three-dimensional mixed perovskite is M2A n-1 BnX 3n+1 , the molecular formula of the zero-dimensional perovskite is A3C2X9, and the molecular formula of the double perovskite is A2CDX6; A in the above molecular formula is selected from ammonium cation, methylamine cation CH3NH3+ 、Formamidinium cation HC(NH2)2 + 、Dimethylamine cation (CH3)2N + , Cesium ion Cs + and rubidium ions Rb + One or more of; B is selected from lead ion Pb 2+ 、Sn 2+ and germanium ion Ge 2+ One or more of; C is selected from bismuth trivalent cation Bi 3+ 、Antimony trivalent cation Sb 3+ 、Aluminum trivalent cation Al 3+ 、Indium trivalent cation In 3+ 、Gallium trivalent cation Ga 3+ One or more of; D is selected from silver monovalent cation Ag + 、Lithium monovalent cation Li + 、Sodium monovalent cation Na + 、Potassium monovalent cation K + 、Rubidium monovalent cation Rb + One or more of; X is selected from iodide ion I - 、Br - and chloride ion Cl - One or more of; M is selected from phenylethylamine cation C6H5CH2CH2NH3 + , ethylamine cation CH3CH2NH3 + 、Propylamine cation CH3(CH2)2NH3 + 、Butylamine cation CH3(CH2)3NH3 + 、Hexamethylenediamine cation NH3(CH2)6NH3 2+ and adamantane amine cation C 10 H 18 N + One or more of; n is a positive integer, when n=1, the molecular formula represents a two-dimensional perovskite, when n≥2, the molecular formula represents a two-dimensional and three-dimensional mixed perovskite.

[0009] Preferably, in step 4), the temperature gradient field has a central temperature of 20 K cm-1 and a peripheral temperature of 20 K cm-1. -1 temperature gradient.

[0010] Preferably, the rated power of the heating unit 1 is 5-20W.

[0011] Further preferably, the heating unit 1 is formed by connecting a plurality of electric heating coils at intervals of 0.3 to 1 cm, and each electric heating coil is connected to the heating unit controller via a separate wire, so that the power of each electric heating coil is controlled separately; Alternatively, the heating unit 1 is a heating rod, and the heating rod is connected to a heating unit controller via a wire to control the power of the heating rod.

[0012] The positive and progressive effects of the present invention are: The present invention proposes a method and device for tempering a perovskite single crystal, which introduces a temperature gradient field on the surface of the single crystal, utilizes the microstress generated by phase change to drive the elimination of domain walls during the slow movement of the temperature gradient field, and achieves uniformity of the scale of ferroelastic domains of a large-area perovskite single crystal. At the same time, the method is compatible with perovskite single crystals of different sizes. The ferroelastic domains in the perovskite single crystal obtained by the method of the present invention are highly ordered, and have lower defect density, stronger fluorescence intensity, higher crystal quality and better carrier transport properties than samples not treated by the method. The crystals treated by the method of the present invention can be used to prepare radiation detectors with better X-ray detection performance and higher γ-ray energy spectrum resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A tempering device for a perovskite single crystal capable of improving the uniformity of domain size; Figure 2 Schematic diagram of crystal tempering in temperature gradient field; Figure 3 This is a photo of MAPbI3 single crystal grown on a 10×10 cm glass substrate; Figure 4 This is a photo of a millimeter-scale MAPbI3 crystal under an infrared polarizing microscope before and after 20 K temperature gradient field treatment; Figure 5 This is a photo of MAPbBr3 single crystal grown on a 10×10 cm glass substrate; Figure 6 This is a photo of a millimeter-scale MAPbBr3 crystal under an infrared polarizing microscope after being treated with a 20 K temperature gradient field. Figure 7 This is a photo of a millimeter-scale MAPbI3 crystal under an infrared polarizing microscope before and after 50 K temperature gradient field treatment; Figure 8 This is a comparison of the X-ray rocking curves of the crystal before and after temperature gradient field tempering treatment; Fig. 9 This is the PL comparison diagram of the crystal before and after temperature gradient field annealing treatment; Fig.10 The SCLC curves of the crystal single electron device before and after temperature gradient field annealing treatment; Fig.11 Comparison curve of crystal tDOS before and after temperature gradient field tempering treatment Fig.12 This is the steady-state photocurrent curve of the crystal after temperature gradient field annealing; Fig.13 This is the steady-state photocurrent curve of the crystal before temperature gradient field annealing treatment; Fig.14 The photocurrent response curve of the X-ray detector prepared by the crystal after temperature gradient field annealing at different X-ray doses; Fig.15 This is a comparison of the response of the 5×5 array radiation detector under visible light before and after the temperature gradient field annealing treatment; Fig.16 This is a comparison of the responses of a 5×5 array radiation detector under different X-ray measurements before and after temperature gradient field annealing. Fig.17 It is the SNR curve after temperature gradient field tempering treatment; Fig.18 The device is made of crystal after temperature gradient field annealing. 241 Energy spectrum resolution curve under Am source. DETAILED DESCRIPTION

[0014] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0015] Example 1 The method of this embodiment is based on a tempering treatment device for a perovskite single crystal that can improve the uniformity of domain size, such as Figure 1 As shown, the device comprises: a sealed box, a heating unit 1, a lifting platform 6 and a heating unit controller; The heating unit 1 is composed of 3 groups of 5W electric heating coils fixedly connected at a spacing of 0.5 cm and arranged in a closed box; The heating unit controller is connected to the electric heating coil. In this embodiment, the heating unit controller adopts an industrial-grade PID precise constant temperature control type temperature control instrument. The industrial-grade PID precise constant temperature control type temperature control instrument measures the temperature (i.e., the center temperature) of the heating coil through a thermocouple temperature sensor, measures the temperature gradient on both sides of the heating area through an infrared temperature sensor, and adjusts the heating power of the three groups of electric heating coils through the industrial-grade PID precise constant temperature control type temperature control instrument so that the temperature gradient reaches the set value, thereby forming the required temperature gradient field on both sides of the heating area; The lifting platform 6 is arranged at the bottom of the closed box, and a working platform for placing the substrate is installed on the upper part; the closed box has two air holes on the shell, which are used to introduce and exhaust the internal gas respectively; In this embodiment, the electric heating coil is installed on two guide rails 4 and 5 through two sliders 2 and 3, so that the electric heating coil can move in the closed box.

[0016] In this embodiment, a 20 K temperature gradient field is used as an example to perform tempering on a millimeter-scale MAPbI3 single crystal. Figure 2 It is a schematic diagram of the tempering process. The specific steps are: 1) Prepare the concentration to be 1.5 mol·L -1 The methylamine lead iodide perovskite precursor solution was stirred at 70 °C for 4 h, and a 10×10 cm glass substrate was preheated on a 75 °C hot plate. The precursor solution was quickly injected between the two substrates. The hot plate temperature was gradually raised to 120 °C and grown for 10 h to obtain the following Figure 3 The single crystal shown.

[0017] 2) The surface of the perovskite single crystal prepared in step 1) is polished with silk to remove large particles of uneven impurities to obtain a smooth and flat crystal surface.

[0018] 3) Place the temperature sensor close to the inside of the heating coil and connect the temperature sensor to the industrial-grade PID precise constant temperature control temperature control instrument.

[0019] 4) Connect the electric heating coil to the industrial-grade PID precise constant temperature control temperature control instrument.

[0020] 5) Nitrogen is introduced through two air holes on the sealed box, and air is discharged from the other air hole to form a protective atmosphere in the sealed box; 6) placing the perovskite single crystal obtained in step 2) on the working platform, and adjusting the height of the lifting platform 6 so that the perovskite single crystal is close to the heating unit 1; 7) Adjust the industrial-grade PID precise constant temperature control instrument to control the heating coil to heat up to 327.4K (0.1K higher than the phase transition temperature of tetragonal-cubic), and form a temperature gradient field on both sides of the area heated by the heating coil; the central temperature of the temperature gradient field is 20 K cm away from the surrounding area. -1 The temperature gradient; 8) Move the electric heating coil so that it moves from above the perovskite single crystal at a speed of 300 μm s -1 The purpose is to sweep the temperature gradient field across the perovskite single crystal at the same speed, so that the temperature of the perovskite single crystal rises to above the tetragonal-cubic phase transition temperature, and the microstress generated by the phase transition is used to drive the elimination of the perovskite single crystal domain wall during the slow movement of the temperature gradient field, completing the tempering treatment, and obtaining the following: Figure 4 A single crystal with uniform domain size is shown.

[0021] Example 2 This embodiment uses the same apparatus as that of Embodiment 1, and uses a 20 K temperature gradient field as an example to perform tempering treatment on a millimeter-scale MAPbBr3 single crystal.

[0022] The difference between this embodiment and embodiment 1 is that: Step 1) Prepare the solution to a concentration of 1.8 mol·L -1 The precursor solution of methylamine lead bromide perovskite was stirred at room temperature for 2 hours. A 10×10 cm glass substrate was placed on a hot stage at room temperature. The precursor solution was quickly injected between the two substrates. The temperature of the hot stage was gradually raised to 80 °C and grown for 10 hours to obtain the following Figure 5 The single crystal shown.

[0023] After tempering treatment, the Figure 6 The single crystal shown.

[0024] Example 3 This embodiment uses the same device as that of embodiment 1, except that the rated power of the electric heating coil is 25 W. This embodiment uses a 50 K temperature gradient field as an example to perform tempering on a millimeter-scale MAPbI3 single crystal. The specific steps are: The difference between this embodiment and embodiment 1 is that: Step 1) Prepare the solution to a concentration of 1.5 mol·L -1 The methylamine lead iodide perovskite precursor solution was stirred at 70 °C for 4 h, and the glass substrate was preheated on a 75 °C hot stage; the precursor solution was quickly injected between the two substrates; the hot stage temperature was gradually raised to 120 °C and grown for 10 h.

[0025] as well as, Step 7) Adjust the industrial-grade PID precise constant temperature control temperature control instrument to control the heating coil to heat up to 347.4K (20K higher than the phase transition temperature of tetragonal-cubic), and form a temperature gradient field on both sides of the area heated by the heating coil; the central temperature of the temperature gradient field is 50 K cm away from the surrounding area. -1 The temperature gradient; Step 8) Move the electric heating coil so that it moves from above the perovskite single crystal at a speed of 300 μm s -1 The purpose is to sweep the temperature gradient field across the perovskite single crystal at the same speed, so that the temperature of the perovskite single crystal rises to above the tetragonal-cubic phase transition temperature, and the microstress generated by the phase transition is used to drive the elimination of the perovskite single crystal domain wall during the slow movement of the temperature gradient field, completing the tempering treatment, and obtaining the following: Figure 7 A single crystal with internal fragmentation is shown.

[0026] In addition to the above embodiments, the heating unit 1 in the present invention may also use a heating rod, wherein a plurality of heating rods are connected at intervals of 0.3 to 1 cm, and each heating rod is connected to the heating unit controller via a wire to individually control the power of the heating rod.

[0027] Effect Example 1 Example 1 Characterization of basic structural properties of crystal before and after temperature gradient field tempering.

[0028] (1) Comparison of crystal quality The crystal quality was compared by X-ray diffraction (XRD) and X-ray rocking curves. Figure 8 It can be seen that the crystal in Example 1 has a narrower half-peak width after temperature gradient field tempering, which proves that temperature gradient field tempering eliminates the internal stress of the crystal, so that the crystal quality is higher.

[0029] (2) Comparison of single crystal fluorescence intensity from Fig. 9 It can be seen that the PL peak of the crystal in Example 1 near 778 nm is narrower and the PL intensity is stronger after temperature gradient field annealing, indicating that temperature gradient field annealing effectively suppresses non-radiative coincidence.

[0030] Effect Example 2 Example 1 Photoelectric properties of the crystal before and after crystal temperature gradient field tempering.

[0031] Comparison of single crystal defects and carrier mobility (1) The space-charge-limited current (SCLC) method is used to test the internal defect density of the crystal.

[0032] Prepare single electron devices for comparison, such as Fig.10 As shown in Figure 1, the electron defect density of the crystal after temperature gradient tempering in Example 1 is calculated to be 5.85×10 9 cm −3 , the electron mobility is 119.0 cm 2 V −1 s −1 , while the electron defect density of the crystal without temperature gradient field tempering in Example 1 is 2.84×10 10 cm −3 , the electron mobility is 44.7 cm 2 V –1 s –1 , it can be seen that the single crystal after temperature gradient tempering has lower defect density and higher carrier mobility.

[0033] (2) The energy-dependent trap state density (tDOS) was measured using thermal admittance spectroscopy (TAS).

[0034] The resulting tDOS spectrum shows three trap bands. The shallower traps are more likely to come from the interior of the single crystal, with Eω values ​​of 0.27 eV (region I) and 0.35 eV (region II); in contrast, the deeper traps are mainly associated with surface defects with Eω values ​​exceeding 0.40 eV (region III). Fig.11As shown, in the single crystal after tempering, the shallower traps associated with the interior of the single crystal (region I and region II) are significantly reduced.

[0035] (3) Calculation of carrier lifetime product The carrier lifetime product is an important indicator for judging the charge collection capacity of a material. The carrier lifetime product of the crystal before and after annealing can be calculated by the steady-state photocurrent method. Fig.12 and Fig.13 It can be calculated that the carrier lifetime of the crystal after tempering in Example 1 is 1.04×10 -2 cm 2 V -1 , which is higher than the carrier lifetime of 1.42×10 -3 cm 2 V -1 , proving that the annealed crystals have better charge collection capabilities, laying the foundation for the preparation of high-performance single-crystal optoelectronic devices.

[0036] Effect Example 3 (1) X-ray detection capability of single crystal devices Take the radiation detection device in Example 1 and test its X-ray detection capability. Fig.14 is the photocurrent response of the device under different radiation doses, and its sensitivity is calculated to be 5.9×10 5 μC Gy air −1 cm −2 Shows high sensitivity.

[0037] (2) Photoelectric response performance of 5×5 large-area single crystal array devices The single crystal in Example 4 was used to make a 5×5 large-area single crystal array device, and the visible light response performance was tested. Fig.15 This is the photocurrent response of the device before and after temperature gradient annealing at 0.1 sun. When the temperature gradient field annealing treatment is performed to eliminate the domain wall, the crystal structure and charge distribution become more uniform, reducing the fluctuation of the electrical signal between each pixel, indicating that the photoelectric performance of the crystal is more uniform after temperature gradient field annealing treatment.

[0038] (3) X-ray response capability of 5×5 large-area single crystal array devices The single crystal in Example 4 was used to make a 5×5 large-area single crystal radiation detection array device to test the X-ray detection capability. Fig.16 The sensitivity trend is shown. The sensitivity of each pixel of the tempered detector is more coordinated. The average sensitivity of the tempered detector is 6.1×10 5 μC Gy air −1 cm−2 , the maximum and minimum values ​​are 6.4×10 5 cm −2 and 5.9×10 5 μC Gy air −1 cm −2 , while the sensitivity before tempering treatment has a larger inter-pixel scattering range, with an average value of 7.0×10 5 μC Gy air −1 cm −2 , the maximum value is 8.8×10 5 μC Gy air −1 cm −2 , the minimum value is 4.4×10 5 μC Gy air −1 cm −2 The sensitivity fluctuations of the detector before and after the flashback were calculated to be 62.9% and 8.2%, respectively.

[0039] (4) γ-ray spectrum resolution of single crystal devices Take the single crystal device of Example 1, after temperature gradient field tempering treatment, as shown in Fig.17 The SNR of the radiation detector shown is 12.0. Fig.18 The crystal device shown exhibits a lower energy spectral resolution of 7.2%.

Claims

1. A tempering method for a perovskite single crystal capable of improving domain size uniformity, characterized in that: The method is based on a tempering treatment device for a perovskite single crystal capable of improving the uniformity of domain scales. The device comprises: a sealed box, a heating unit (1), a lifting platform (6) and a heating unit controller; The heating unit controller is connected to the heating unit (1); the lifting platform (6) is arranged at the bottom of the sealed box, and a working platform for placing a substrate is installed on the upper part; the sealed box has two air holes on the shell, which are used to introduce and exhaust the internal gas respectively; the heating unit (1) is used to form a temperature field with a temperature gradient on both sides of the heating area; in addition, the heating unit (1) is movably arranged in the sealed box; The specific steps of the tempering treatment method are: 1) Prepare a perovskite single crystal, and after polishing to remove impurities, obtain a perovskite single crystal with a smooth surface; 2) Nitrogen is introduced through two air holes on the sealed box, and air is discharged from the other air hole to form a protective atmosphere in the sealed box; 3) placing the perovskite single crystal obtained in step 1) on a working platform, and adjusting the height of the lifting platform (6) so that the perovskite single crystal is close to the heating unit (1); 4) adjusting the heating unit controller to control the heating unit (1) to heat up to 0.1-20K above the tetragonal-cubic phase transition temperature, thereby forming a temperature gradient field on both sides of the region heated by the heating unit (1); the central temperature of the temperature gradient field is above the tetragonal-cubic phase transition temperature, and there is a temperature difference of 5-35 K cm between the central temperature and the surrounding area. -1 The temperature gradient; 5) Heating unit (1) Heats the perovskite single crystal at a speed of 10-2000 μm s -1 The temperature gradient field is swept across the perovskite single crystal at the same speed to complete the tempering treatment.

2. The tempering method of perovskite single crystal capable of improving domain size uniformity according to claim 1, characterized in that: Step 1) The preparation method of the perovskite single crystal is selected from: a cooling growth method, a reverse temperature growth method, a Bridgman crystal growth method, a solvent diffusion growth method, a solvent evaporation growth method and a derivative growth method thereof.

3. The tempering method of perovskite single crystal capable of improving domain size uniformity according to claim 1, characterized in that: The perovskite single crystal in step 1) is a three-dimensional perovskite, a two-dimensional perovskite, a two-dimensional three-dimensional mixed perovskite, a zero-dimensional perovskite or a double perovskite crystal.

4. The tempering method of perovskite single crystal capable of improving domain size uniformity according to claim 3, characterized in that: The molecular formula of the three-dimensional perovskite is ABX3, and the molecular formula of the two-dimensional perovskite or the two-dimensional and three-dimensional mixed perovskite is M2A n-1 BnX 3n+1 , the molecular formula of the zero-dimensional perovskite is A3C2X9, and the molecular formula of the double perovskite is A2CDX6; A in the above molecular formula is selected from ammonium cation, methylamine cation CH3NH3 + 、Formamidinium cation HC(NH2)2 + 、Dimethylamine cation (CH3)2N + , Cesium ion Cs + and rubidium ions Rb + One or more of; B is selected from lead ion Pb 2+ 、Sn 2+ and germanium ion Ge 2+ One or more of; C is selected from bismuth trivalent cation Bi 3+ 、Antimony trivalent cation Sb 3+ 、Aluminum trivalent cation Al 3+ 、Indium trivalent cation In 3+ 、Gallium trivalent cation Ga 3+ One or more of; D is selected from silver monovalent cation Ag + 、Lithium monovalent cation Li + 、Sodium monovalent cation Na + 、Potassium monovalent cation K + 、Rubidium monovalent cation Rb + One or more of; X is selected from iodide ion I - 、Br - and chloride ion Cl - One or more of; M is selected from phenylethylamine cation C6H5CH2CH2NH3 + , ethylamine cation CH3CH2NH3 + 、Propylamine cation CH3(CH2)2NH3 + 、Butylamine cation CH3(CH2)3NH3 + 、Hexamethylenediamine cation NH3(CH2)6NH3 2+ and adamantane amine cation C 10 H 18 N + One or more of; n is a positive integer, when n=1, the molecular formula represents a two-dimensional perovskite, when n≥2, the molecular formula represents a two-dimensional and three-dimensional mixed perovskite.

5. The tempering method of perovskite single crystal capable of improving domain size uniformity according to claim 1, characterized in that: The rated power of the heating unit (1) is 5~20W.

6. The tempering method of perovskite single crystal capable of improving domain size uniformity according to claim 5, characterized in that: The heating unit (1) is composed of a plurality of electric heating coils connected at intervals of 0.3 to 1 cm, each electric heating coil being connected to a heating unit controller via a separate wire, and the power of each electric heating coil being controlled individually.

7. The tempering method of perovskite single crystal capable of improving domain size uniformity according to claim 5, characterized in that: The heating unit (1) is a heating rod, and the heating rod is connected to a heating unit controller via a wire to control the power of the heating rod.

8. The tempering method of perovskite single crystal capable of improving domain size uniformity according to claim 1, characterized in that: In step 4), the temperature gradient field at the center of the temperature is 20 K cm away from the surrounding area. -1 temperature gradient.

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