Preparation method and application of perovskite single crystal material

Abstract

The invention relates to the technical field of semiconductor materials, and particularly discloses a preparation method and application of a perovskite single crystal material. On the basis of the prepared MAPbBr3 single crystal, epitaxial growth of the MAPbBr2. 7Cl0.3 single crystal on the surface of the MAPbBr3 single crystal is achieved by changing the proportion of precursor halogen components, a continuous and complete single crystal heterostructure is formed, the structure can remarkably regulate and control the band gap structure of the material, the carrier separation efficiency and the photoelectric response capacity are improved, and the MAPbBr3 single crystal is finally used for preparing a high-performance photoconductive device. Moreover, the technological process is simple and convenient, the controllability is high, a secondary growth process combining inverse temperature crystallization with precursor component regulation and control is adopted, the operation steps are clear, the reproducibility is good, and the method is suitable for laboratory-scale preparation and future industrial popularization.

Description

Technical Field

[0001] This application relates to the field of semiconductor materials technology, and more specifically, to a method for preparing perovskite single crystal materials and their applications. Background Technology

[0002] Organic-inorganic hybrid perovskite materials have attracted widespread attention in recent years due to their excellent photoelectric properties, particularly showing broad application prospects in fields such as solar cells, photodetectors, X-ray imaging, and neutron detection. Compared to polycrystalline thin films, perovskite single crystals possess higher carrier mobility, lower trapped state density, and longer carrier lifetime, making them more promising for the fabrication of high-performance optoelectronic devices. Among them, MAPbBr3 single crystals have become one of the hot materials for research and application due to their excellent stability, moderate band gap (~2.2 eV), and controllable growth process.

[0003] However, MAPbBr3 single-crystal devices still face challenges in practical applications, such as fixed bandgap, difficulty in interface control, and limited electrode injection efficiency, which restrict further improvements in their photoelectric conversion efficiency and detection sensitivity. Traditional methods mainly focus on preparing novel mixed-halogen single crystals through solution composition control, but it is difficult to precisely control the mixed-halogen ratio and crystal interface quality, and it is easy to form impurity phases or lattice distortions, affecting device stability and repeatability.

[0004] In recent years, the reverse-temperature crystallization solution method has become the most commonly used method for preparing MAPbBr3 single crystals (Nature Communications, 2015, 6(1): 1-6; Science China Materials, 2017, 60(11): 1063-1078; Journal of Materials Science, 2017, 52(13): 7907-7916.). The solubility curve shows that the solubility of MAPbBr3 in DMF decreases with increasing temperature. Based on the inverse relationship between the solubility of hybrid perovskite materials in organic solvents and temperature, the solubility is reduced by increasing the temperature, thus obtaining the supersaturation required for crystal nucleation to achieve the nucleation conditions for crystal growth. The supersaturated state then provides the driving force for crystal growth. Currently, several research groups have successfully prepared MAPbBr3 single crystals using the reverse temperature crystallization solution method. However, due to the lack of control over the growth process, multiple nucleation sites, crystal stacking and adhesion are prone to occur in the early stage of crystal growth, resulting in the crystal size being limited to the millimeter level. Therefore, improving the yield of single crystals and growing high-quality, large-size MAPbBr3 single crystals remains a problem that needs to be solved.

[0005] Therefore, how to construct a functionalized heterostructure with a clear interface structure while maintaining the excellent crystal quality of MAPbBr3 has become a key technical challenge in improving the performance of perovskite devices. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides a method for preparing perovskite single-crystal heterostructure materials and their applications. Specifically, it involves altering the halogen composition ratio of the precursor to achieve MAPbBr3 based on a previously prepared MAPbBr3 single crystal. 2.7 Cl 0.3 Single crystals grow epitaxially on their surface to form continuous and complete single-crystal heterostructures.

[0007] In a first aspect, this application provides a method for preparing a perovskite single-crystal heterostructure material, employing the following technical solution: First, a MAPbBr3 precursor solution was prepared in an N,N-dimethylformamide (DMF) solvent system using methylamine bromide (MABr) and lead bromide (PbBr2) via reverse temperature crystallization, and high-quality MAPbBr3 single crystals were grown under controlled temperature conditions.

[0008] The resulting single crystal was then transferred to MAPbBr with adjusted halogen composition. 2.7 Cl 0.3 In the precursor solution, the epitaxial growth step continues, causing the outer periphery of the single crystal to gradually grow with Cl... - Doped epitaxial layers are used to obtain single-crystal materials with heterostructure interfaces.

[0009] After cooling, the sample was removed, dried, and polished to finally obtain the target heterostructure single crystal.

[0010] The specific preparation steps are as follows: Equimolar amounts of MABr and PbBr2 were dissolved in DMF and stirred to obtain a MAPbBr3 precursor solution. The MAPbBr3 precursor was heated and subjected to a first growth to obtain a regular seed crystal. The obtained regular seed crystal was transferred to a new MAPbBr3 precursor solution with the same composition, heated, and subjected to a second growth to obtain a MAPbBr3 single crystal.

[0011] 0.7 mol PbBr2, 0.3 mol PbCl2, 0.7 mmol MABr, and 0.3 mmol MACl were dissolved in DMF and stirred to obtain MAPbBr. 2.7 Cl 0.3 Precursor solution: MAPbBr3 single crystals are transferred into a MAPbBr3 precursor solution, heated, and epitaxially grown to obtain a MAPbBr3 precursor solution. 2.7 Cl0.3 The cladding layer is a heterostructured single crystal, namely a perovskite single crystal heterostructure material.

[0012] More preferably, during the first growth process, the temperature of the MAPbBr3 precursor solution is 60℃-80℃, and the growth time is 4-6h.

[0013] More preferably, during the second growth process, the temperature of the MAPbBr3 precursor solution is 60℃-80℃, and the growth time is 24-26h.

[0014] More preferably, the specific steps for epitaxial growth are: preparing Cl... - MAPbBr at concentrations of 0.1 mol / L, 0.2 mol / L, and 0.3 mol / L were used. 2.7 Cl 0.3 Precursor solutions: MAPbBr3 single crystals were sequentially placed in 0.1 mol / L, 0.2 mol / L, and 0.3 mol / L MAPbBr solutions. 2.7 Cl 0.3 Epitaxial growth was performed in the precursor solution and heated to obtain a MAPbBr matrix with an outer layer. 2.7 Cl 0.3 Heterogeneous single crystal with cladding layer.

[0015] More preferably, MAPbBr3 single crystals are prepared in MAPbBr solutions of 0.1 mol / L, 0.2 mol / L, and 0.3 mol / L. 2.7 Cl 0.3 The growth temperature and time in the precursor solution were: 45-50℃ for 3 hours, 50-55℃ for 4 hours, and 55-60℃ for 6 hours.

[0016] Secondly, this application provides an application of perovskite single-crystal heterostructure materials in radiation detection devices, particularly the fabrication and application of photoconductive devices, specifically employing the following technical solution: The surface of the heterostructured single crystal obtained above is polished and cleaned. Au and Ag electrode layers are then deposited on both sides of the heterostructured single crystal using magnetron sputtering to form an asymmetric structure device.

[0017] When the asymmetric structure device obtained from the fabrication is used to prepare photoconductive devices, the dark current / photocurrent ratio and response sensitivity can be significantly improved.

[0018] Further confirmation using X-ray diffraction (XRD), ultraviolet-visible absorption spectroscopy (UV-Vis), and steady-state and time-resolved fluorescence (TRPL) methods revealed that this heterostructured perovskite possesses good crystal quality, a clear interface structure, and excellent carrier dynamics.

[0019] More preferably, the sandpaper used for polishing heterogeneous single crystals has a grit of 5000-6000.

[0020] More preferably, the heterostructured single crystal is polished to MAPbBr 2.7 Cl 0.3 The coating thickness is 1-1.5mm.

[0021] In summary, this application has the following beneficial effects: Constructing high-quality heterostructure single-crystal materials: By precisely controlling the crystal interface and halogen doping ratio through a two-step growth method, the integrity of the structure and single-crystal characteristics are guaranteed, avoiding the phase separation and polycrystalline structure problems commonly found in traditional mixed solution methods.

[0022] Achieving tunable band structure and light absorption performance: by introducing Cl - Adjusting the band gap broadens the absorption boundary of perovskite in the visible light range, improves the response to short-wavelength light, and facilitates high-sensitivity detection.

[0023] Improving the performance of photoconductive devices: The fabricated heterostructure devices exhibit higher open-circuit voltage, lower dark current, and stronger photocurrent response, making them suitable for high-sensitivity ultraviolet and visible light detection scenarios.

[0024] The process is simple and highly controllable: It adopts a secondary growth process that combines reverse temperature crystallization with precursor composition control. The operation steps are clear, the reproducibility is good, and it is suitable for laboratory-scale preparation and future industrialization.

[0025] In summary, this invention provides a well-defined and high-performance perovskite single-crystal heterostructure and its device construction method, which solves the problems of untunable bandgap, low electrode injection efficiency, and weak photoelectric response in perovskite single-crystal devices, and has significant application prospects and engineering value. Attached Figure Description

[0026] Figure 1 This is an X-ray diffraction pattern of the perovskite single-crystal heterostructure material prepared in Example 1 of this application; Figure 2 The UV-Vis absorption spectrum of the perovskite single-crystal heterostructure material prepared in Example 1 of this application is shown. Figure 3 This is a scanning electron microscope image of the perovskite single-crystal heterostructure material prepared in Example 1 of this application; Figure 4 This is a time-resolved fluorescence lifetime test image of the perovskite single-crystal heterostructure device prepared in Example 2 of this application; Figure 5 This is an IV characteristic curve of the perovskite single-crystal heterostructure device prepared in Example 2 of this application under dark conditions; Figure 6 The IV curve of the perovskite single-crystal heterostructure device prepared in Example 2 of this application under white light irradiation conditions; Figure 7 The image shows the It response curve of the perovskite single-crystal heterostructure device prepared in Example 2 of this application under a 5V bias voltage. Detailed Implementation

[0027] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application.

[0028] Furthermore, it should be understood that the one or more method steps mentioned in this application do not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and is not intended to limit the order of the method steps or limit the scope of implementation of this application. Changes or adjustments to their relative relationships, without substantially altering the technical content, shall also be considered as within the scope of implementation of this application.

[0029] Unless otherwise specified, the experimental conditions used in the examples are generally in accordance with conventional conditions in the art or the conditions recommended by the reagent company. Unless otherwise specified, the materials and reagents used in the examples can be purchased commercially.

[0030] Example 1: Preparation of perovskite single-crystal heterostructure materials: S1. MABr and PbBr2 in a 1:1 molar ratio were dissolved in 1 mL of DMF to form a 1 mol / L MAPbBr3 precursor solution. After stirring at room temperature for 1 h, the solution was placed in a sealed beaker with a perforated opening. The temperature was raised to 80 °C and maintained for 5 h to obtain a regular seed crystal. The obtained regular seed crystal was transferred to 0.7 mL of a new MAPbBr3 precursor solution of the same composition, heated to 80 °C, and maintained for 24 h to obtain a cubic MAPbBr3 single crystal with a side length of 5 mm.

[0031] S2, prepare three portions of Cl - MAPbBr at different concentrations 2.7 Cl 0.3Precursor solutions, aq1, aq2, and aq3, were used. MAPbBr3 single crystals were placed in solution aq1 and grown at 45°C for 3 hours. Then, solution aq1 was removed using a pipette, and solution aq2 was slowly injected along the reactor wall. Growth was continued at 50°C for 4 hours. Then, solution aq2 was removed again using a pipette, and solution aq3 was slowly injected along the reactor wall. Growth was continued at 55°C for 6 hours, resulting in a MAPbBr3 crystal with a morphology of [missing information - likely a specific type of crystal]. 2.7 Cl 0.3 The cladding layer is a heterostructured single crystal, namely a perovskite single crystal heterostructure material.

[0032] Cl in solutions aq1, aq2, and aq3 - The concentrations were 0.1 mol / L, 0.2 mol / L, and 0.3 mol / L, respectively, and the component ratios are shown in Table 1.

[0033] Table 1 Example 2 Device Construction The perovskite single-crystal heterostructure material prepared in Example 1 was polished to a thickness of 1 mm using 5000-grit sandpaper. Then, 100 nm thick Ag electrodes and 120 nm thick Au electrodes were deposited on the polished upper and lower surfaces, respectively, using magnetron sputtering. The device configuration was Au / MAPbBr3-MAPbBr. 2.7 Cl 0.3 / Ag. The electrodes are connected in a small area via Ag wires and conductive silver paste, forming a complete device structure. The electrode area is approximately 4 mm². 2 It is assembled on a glass support base.

[0034] Comparative Example 1: Preparation of pure MAPbBr3 single crystals: MABr and PbBr2 in a 1:1 molar ratio were dissolved in 1 mL of DMF to form a MAPbBr3 precursor solution with a concentration of 1 mol / L. After stirring at room temperature for 1 h, the solution was placed in a sealed beaker with a perforation, heated to 80 °C, and held for 5 h to obtain regular seed crystals. The obtained regular seed crystals were transferred to 0.7 mL of a new MAPbBr3 precursor solution with the same composition, heated to 80 °C, and held for 24 h to obtain MAPbBr3 single crystals with a side length of 5 mm and a cubic shape.

[0035] Performance testing Figure 1 The image shows the X-ray diffraction (XRD) pattern of the perovskite single-crystal heterostructure material obtained in Example 1. The image displays clear and sharp diffraction peaks, which are basically consistent with the diffraction peak positions of the standard MAPbBr3 crystal. A slight shift is observed in the high-angle region, indicating that Cl... -Doping does indeed cause slight lattice shrinkage, thus proving that the epitaxial layer and the core crystal maintain good consistency in crystal structure.

[0036] Figure 2 The image shows the UV-Vis absorption spectrum of the perovskite single-crystal heterostructure material obtained in Example 1. The results show a blue shift in the absorption edge after epitaxial growth, indicating that Cl... - The introduction of [a specific component] widens the band gap and enhances the absorption performance in the ultraviolet region. Compared with pure MAPbBr3, this heterostructure exhibits enhanced absorption in the 550-600 nm wavelength range, indicating that it will have stronger response capability in photodetectors.

[0037] Figure 3 This is a scanning electron microscope (SEM) image of the perovskite single-crystal heterostructure material obtained in Example 1. The image shows a smooth crystal surface without obvious cracks or polycrystalline boundaries, and a clear and continuous interface, indicating that the epitaxial layer and core layer of the heterostructure have grown well without obvious delamination or defects, which is conducive to achieving seamless electron transport.

[0038] Figure 4 The results of time-resolved photoluminescence (TRPL) testing of the device obtained in Example 2 are shown. The TRPL spectrum indicates that Cl... - The small amount of doping improves the carrier transport and separation efficiency. Compared with pure MAPbBr3 single crystal, the heterostructure single crystal has a shorter carrier lifetime decay time, indicating that its exciton separation is more efficient and the charge recombination rate is reduced, which helps to enhance the photoelectric conversion efficiency.

[0039] Figure 5 The figure shows the IV characteristic curve (dark current) of the device obtained in Example 2 under dark conditions. This figure demonstrates that the device exhibits extremely low leakage current in the absence of light, with a dark current of 10... -7 The order of magnitude A indicates that the device interface has good band matching, uniform potential barrier, and a good basis for switching ratio.

[0040] Figure 6 The image shows the IV curve (photocurrent) of the device obtained in Example 2 under white light illumination. After illumination, the current increased significantly by two orders of magnitude, reaching 10. -5 -10 -4 A indicates that the device has a strong photoresponse and that charge carriers are effectively separated at the heterogeneous interface, demonstrating the potential application value of this structure in photoconductive detectors.

[0041] Figure 7The figure shows the It response curve (switching response) of the device obtained in Example 2 under a 5V bias voltage. As can be seen from the figure, under the cyclic change of light illumination and switching, the current value has good repeatability and fast response speed, with a response time of less than 20ms, showing good light response stability and switching ratio. This indicates that the heterostructure helps to improve the response speed and repeatability of the device.

[0042] In summary, the method proposed in this application based on MAPbBr3 single crystal and MAPbBr 2.7 Cl 0.3 Epitaxial heterostructure devices not only achieve precise and controllable bandgap modulation and heterogeneous interface design in terms of material structure, but also demonstrate excellent photoelectric response and low dark current characteristics in actual device performance testing, possessing good scientific research and industrial transformation value.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a perovskite single-crystal heterostructure material, characterized in that, The preparation steps include the following: S1, Dissolve equimolar amounts of MABr and PbBr2 in DMF, stir to dissolve, and obtain MAPbBr3 precursor solution. Heat the MAPbBr3 precursor and perform the first growth to obtain a regular seed crystal. Transfer the obtained regular seed crystal to a new MAPbBr3 precursor solution with the same composition, heat and perform the second growth to obtain MAPbBr3 single crystal. S2, PbBr2, PbCl2, MABr, and MACl are dissolved in DMF and stirred until dissolved to obtain MAPbBr. 2.7 Cl 0.3 Precursor solution: MAPbBr3 single crystals are transferred into a MAPbBr3 precursor solution, heated, and epitaxially grown to obtain a MAPbBr3 precursor solution. 2.7 Cl 0.3 The cladding layer is a heterostructured single crystal, namely a perovskite single crystal heterostructure material.

2. The method for preparing perovskite single-crystal heterostructure material according to claim 1, characterized in that, During the first growth process, the temperature of the MAPbBr3 precursor solution was 60℃-80℃, and the growth time was 4-6h.

3. The method for preparing perovskite single-crystal heterostructure material according to claim 1, characterized in that, During the second growth process, the temperature of the MAPbBr3 precursor solution was 60℃-80℃, and the growth time was 24-26h.

4. The method for preparing perovskite single-crystal heterostructure material according to claim 1, characterized in that, In step S2, prepare Cl - MAPbBr at concentrations of 0.1 mol / L, 0.2 mol / L, and 0.3 mol / L were used. 2.7 Cl 0.3 Precursor solutions: MAPbBr3 single crystals were sequentially placed in 0.1 mol / L, 0.2 mol / L, and 0.3 mol / L MAPbBr solutions. 2.7 Cl 0.3 Epitaxial growth was performed in the precursor solution and heated to obtain a MAPbBr matrix with an outer layer. 2.7 Cl 0.3 Heterogeneous single crystal with coating layer.

5. The method for preparing perovskite single-crystal heterostructure material according to claim 4, characterized in that, MAPbBr3 single crystals were obtained from MAPbBr3 solutions at concentrations of 0.1 mol / L, 0.2 mol / L, and 0.3 mol / L. 2.7 Cl 0.3 The growth temperature and time in the precursor solution were: 45-50℃ for 3 hours, 50-55℃ for 4 hours, and 55-60℃ for 6 hours.

6. A perovskite single-crystal heterostructure material, characterized in that, The perovskite single-crystal heterostructure material is prepared by the preparation method described in any one of claims 1-5.

7. The application of the perovskite single-crystal heterostructure material according to claim 6 in photoconductive devices.

8. The application of the perovskite single-crystal heterostructure material according to claim 7 in photoconductive devices, characterized in that, The surface of the heterostructure single crystal is polished and cleaned. Au and Ag electrode layers are deposited on both sides of the heterostructure single crystal by magnetron sputtering to form an asymmetric structure device.

9. The application of the perovskite single-crystal heterostructure material according to claim 8 in photoconductive devices, characterized in that, The sandpaper used for polishing heterogeneous single crystals is 5000-6000 grit.

10. The application of the perovskite single-crystal heterostructure material according to claim 7 in photoconductive devices, characterized in that, Heterogeneous single crystal polishing to MAPbBr 2.7 Cl 0.3 The coating thickness is 1-1.5mm.

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