Method for rapidly growing single crystal perovskite thin film
By guiding the epitaxial nucleation and directional fusion of perovskite nanosheets on a staggered sapphire substrate, the problems of long growth time and high cost of single-crystal perovskite are solved, and rapid and efficient preparation of single-crystal thin films is achieved, which is suitable for large-scale applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-09
- Publication Date
- 2026-04-03
AI Technical Summary
Existing methods for growing single-crystal perovskites are limited by slow crystal growth kinetics, resulting in long growth cycles, high costs, and stringent requirements for substrate treatment, making large-scale applications difficult.
By employing co-orientation driven fusion technology, using staggered sapphire substrates and high-temperature annealing, epitaxial nucleation and directional fusion of perovskite nanosheets on the substrate are achieved, enabling rapid growth of high-quality single-crystal perovskite thin films.
The synthesis time for millimeter-scale high-quality perovskite single-crystal thin films is significantly shortened within one minute, reducing production costs and simplifying the process, making it suitable for large-scale preparation and practical applications.
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Figure CN121781275A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of single-crystal thin film growth technology, and specifically to a method for rapidly growing single-crystal perovskite thin films. Background Technology
[0002] In recent years, metal halide perovskite materials have sparked a global research boom as a revolutionary class of optoelectronic materials. These materials, with their unique ABX3 crystal structure (where A is an organic or inorganic cation, B is a metal cation, and X is a halide anion), excellent light absorption coefficient, superior carrier mobility, long carrier diffusion lengths on the micrometer scale, and tunable bandgap characteristics, have demonstrated unprecedented application potential in the field of optoelectronics. Simultaneously, their solution processing characteristics provide an ideal platform for the low-cost fabrication of high-performance optoelectronic devices, making them a key material system for driving the development of next-generation photovoltaic technology and optoelectronic integration.
[0003] Currently, the research and application of perovskite materials mainly follow two technological paths: polycrystalline thin films and single-crystal materials. Polycrystalline perovskite thin films, with their relatively mature solution preparation processes (such as spin coating and blade coating), have achieved breakthrough progress in the field of solar cells, with laboratory-certified efficiencies exceeding 27%, comparable to mature commercial crystalline silicon technology. However, the inherent grain boundaries, defects, and ion migration problems in polycrystalline thin films severely restrict further improvement in device performance and long-term stability. In contrast, perovskite single-crystal materials, due to their perfect structural integrity, extremely low defect density, and excellent environmental stability, are considered a fundamental way to overcome these bottlenecks.
[0004] Traditional perovskite single-crystal thin films are mainly prepared using techniques such as spatial confinement and chemical vapor deposition. The spatial confinement method involves sandwiching a precursor solution between two substrates, then heating it to continuously evaporate and react, growing the perovskite single crystal. This confined space is designed to maintain a low supersaturation of the precursor to prevent random nucleation and achieve the desired growth of a single-crystal perovskite film. Therefore, the growth process is extremely slow, typically requiring several hours or even days. Furthermore, it is highly sensitive to interfacial properties, requiring precise control of the interfacial tension between the precursor solution and the substrate; any deviation can lead to uneven nucleation or growth failure. In addition, the complex spatial confinement structure requires precise alignment of the two PTAA / ITO substrates and control of the gap. After filling with the precursor solution, the substrates must be separated after growth, increasing process complexity and the risk of contamination. Chemical vapor deposition employs a "tube-in-tube" structure design with the end of a sealed inner tube facing the direction of the carrier gas flow, which helps maintain a stable laminar flow state in the reaction chamber, thereby achieving controllable growth. However, this method is based on slow crystal growth kinetics, which is time-consuming, energy-intensive, and costly. In addition, it has strict requirements for substrate pretreatment. Before growth, the substrate needs to be atomically planarized (hot water etching + HF buffer treatment), which is a complicated and corrosive process. If not handled properly, it may lead to epitaxial growth failure or the formation of discontinuous nanostructures.
[0005] As can be seen from the above, existing methods for growing single-crystal perovskites are generally limited by slow crystal growth kinetics, requiring the maintenance of low precursor supersaturation to prevent random nucleation. Growth cycles typically last for hours or even days, severely hindering their large-scale application. Therefore, researching and developing a method for rapidly growing high-quality single-crystal perovskite thin films is of great significance. Summary of the Invention
[0006] This invention addresses the shortcomings of existing technologies by providing a method for rapidly growing single-crystal perovskite thin films. Employing a "co-orientation driven fusion" growth technique, perovskite nanosheets are guided to undergo epitaxial nucleation and directional fusion on a miscut sapphire substrate, successfully achieving the fabrication of millimeter-scale high-quality perovskite single-crystal thin films within one minute. This ultrafast single-crystal growth technology not only overcomes the key bottleneck in perovskite material preparation but also provides a novel technological paradigm for realizing the leap from basic research to industrial application.
[0007] To address the aforementioned technical problems, the first aspect of this invention provides a method for rapidly growing single-crystal perovskite thin films, comprising the following steps:
[0008] S1. Anneal the sapphire substrate with C-plane offset from A-plane by 1-2° to obtain a substrate with parallel steps.
[0009] S2. Mix and stir AX3, BX and organic solvent to obtain B3A2X9 precursor solution;
[0010] Wherein, A is selected from Bi and Sb; B is selected from Cs and MA (methylamine cation); and X is selected from I and Br.
[0011] S3. Take the B3A2X9 precursor solution, add a surfactant, and mix to obtain a spin-coating solution;
[0012] S4. Spin-coating the spin-coating solution onto the surface of the substrate and annealing it to obtain a single-crystal perovskite thin film.
[0013] This invention employs a C / A-plane sapphire substrate with a specific angle of miscutting and undergoes high-temperature annealing. Driven by the thermal energy provided by the high temperature, surface atoms diffuse and rearrange, breaking unstable chemical bonds and forming new, more stable chemical bonds. Ultimately, the high-energy, irregular surface is transformed into a thermodynamically stable structure composed of low-energy A-planes with the lowest energy. The low-index planes, like "building blocks," form parallel steps through the combination of steps and vertical surfaces. By selecting a specific miscutting angle and annealing temperature, the resulting step height has high adaptability, allowing the selected perovskite material lattice to match it. This enables several nanosheets to grow epitaxially along the same crystallographic orientation and eventually fuse into a larger single crystal.
[0014] This invention enables high-quality epitaxial growth of ionic perovskites without the need for complex vapor deposition equipment, through simple solution processing and pre-treated substrates. This provides a lower-cost and more universal path for the integration of perovskites with mainstream semiconductor processes.
[0015] The method of this invention significantly shortens the synthesis time, making its large-scale preparation and practical application prospects promising; the operation is simple, the annealing temperature after spin coating is only tens of degrees Celsius, the equipment requirements are low and it does not need to be carried out in a glove box, which greatly saves energy consumption and significantly reduces production costs.
[0016] Furthermore, in S1, the annealing treatment is performed at a temperature of 1100-1200℃ for 8-10 hours in an air atmosphere.
[0017] Furthermore, in S2, the molar ratio of AX3 to BX is 2:(2.5-3.5).
[0018] And / or, the concentration of AX3 is 0.4-0.5M.
[0019] Furthermore, in S2, the stirring temperature is 45-55°C.
[0020] Furthermore, in S3, the volume ratio of the B3A2X9 precursor solution to the surfactant is (1.2-1.8):1.
[0021] Furthermore, in S3, the surfactant is valeric acid.
[0022] Furthermore, in S3, the conditions for the mixing treatment are: centrifugation speed of 7000-9000 rad / min and time of 10-20 min.
[0023] Furthermore, in S4, the spin coating conditions are: rotation speed 1200-1800 rad / min, time 20-40 s.
[0024] Furthermore, in S4, the annealing treatment is carried out at a temperature of 60-70°C for 30-50 seconds, and the atmosphere is air.
[0025] The second aspect of the present invention provides a single-crystal perovskite thin film prepared by the method described in the first aspect.
[0026] The beneficial effects of this invention are:
[0027] This invention employs a "co-orientation-driven fusion" growth technique, which guides perovskite nanosheets to undergo epitaxial nucleation and directional fusion on a staggered sapphire substrate. This successfully enables the preparation of millimeter-scale high-quality perovskite single-crystal thin films within one minute, significantly shortening the synthesis time and making its large-scale preparation and practical application prospects promising.
[0028] This invention eliminates the need for complex vapor deposition equipment and achieves high-quality epitaxial growth through simple solution processing and pretreatment of the substrate. This provides a lower-cost and more universal path for the integration of perovskite with mainstream semiconductor processes. Attached Figure Description
[0029] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0030] Figure 1 This is a flowchart of the method for rapidly growing single-crystal perovskite thin films according to the present invention;
[0031] Figure 2 This is an AFM (atomic force microscope) image of the substrate after annealing in Example 1;
[0032] Figure 3 Optical microscope images of the single crystal growth process in Example 1;
[0033] Figure 4 Optical microscope images and regional EBSD characterization of the Cs3Bi2I9 single-crystal thin film synthesized in Example 1;
[0034] Figure 5 Raman mapping and Raman characteristic peak diagram of the Cs3Bi2I9 single crystal thin film synthesized in Example 1;
[0035] Figure 6 The image shows the XRD pattern of the Cs3Bi2I9 single-crystal thin film synthesized in Example 1.
[0036] Figure 7 Microscopic image of the Cs3Bi2Br9 single crystal thin film synthesized in Example 2;
[0037] Figure 8 Raman spectroscopy pattern of the Cs3Bi2Br9 single crystal thin film synthesized in Example 2;
[0038] Figure 9 Microscopic image of the Cs3Sb2Br9 single crystal thin film synthesized in Example 3;
[0039] Figure 10 Raman spectroscopy pattern of the Cs3Sb2Br9 single crystal thin film synthesized in Example 3;
[0040] Figure 11 Microscopic image of the MA3Bi2I9 single crystal thin film synthesized in Example 4;
[0041] Figure 12 Raman spectroscopy pattern of MA3Bi2I9 single crystal thin film synthesized in Example 4;
[0042] Figure 13 Microscopic image of the Cs3Bi2I9 thin film synthesized in Comparative Example 1;
[0043] Figure 14 The image shows a microscope image of the Cs3Bi2I9 thin film synthesized in Comparative Example 2. Detailed Implementation
[0044] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0045] This embodiment relates to a method for rapidly growing single-crystal perovskite thin films, see reference... Figure 1 It includes the following steps:
[0046] S1. Anneal the sapphire (Al2O3) substrate with the C-plane offset from the A-plane by 1-2° to obtain a substrate with parallel steps.
[0047] S2. Mix and stir AX3, BX and organic solvent to obtain B3A2X9 precursor solution;
[0048] Among them, A is selected from Bi and Sb; B is selected from Cs and MA; and X is selected from I and Br.
[0049] S3. Take the B3A2X9 precursor solution, add a surfactant, and mix to obtain a spin-coating solution;
[0050] S4. Spin-coating the spin-coating solution onto the surface of the substrate and annealing it to obtain a single-crystal perovskite thin film.
[0051] This embodiment employs a C / A-plane sapphire substrate with a specific angled shearing followed by high-temperature annealing. Driven by the thermal energy provided by the high temperature, surface atoms diffuse and rearrange, breaking unstable chemical bonds and forming new, more stable ones. Ultimately, the high-energy, irregular surface is transformed into a thermodynamically stable structure composed of low-energy A-planes with the lowest energy. These low-index planes, like building blocks, form parallel steps through a combination of steps and vertical surfaces. By selecting a specific shearing angle and annealing temperature, the resulting step heights are highly adaptable, allowing the selected perovskite material's lattice to match. This enables several nanosheets to grow epitaxially along the same crystallographic orientation and eventually fuse into a larger single crystal. For ion-type perovskites, high-quality epitaxial growth can be achieved without complex vapor deposition equipment, using only simple solution processing and pre-treated substrates. This provides a lower-cost and more universal path for integrating perovskites with mainstream semiconductor processes. This method significantly reduces the synthesis time, making its large-scale preparation and practical application prospects promising. It is simple to operate, with the annealing temperature after spin coating being only a few tens of degrees Celsius. It has low requirements for equipment and does not need to be carried out in a glove box, which greatly saves energy and significantly reduces production costs.
[0052] In a preferred embodiment, in S1, the annealing treatment is carried out at a temperature of 1100-1200°C for 8-10 hours in an air atmosphere.
[0053] In a preferred embodiment, in S2, the molar ratio of AX3 to BX is 2:(2.5-3.5); the concentration of AX3 is 0.4-0.5M; and the stirring temperature is 45-55℃.
[0054] In a preferred embodiment, in S3, the volume ratio of the B3A2X9 precursor solution to the surfactant is (1.2-1.8):1; the surfactant is valeric acid; and the mixing conditions are: centrifugation speed 7000-9000 rad / min, time 10-20 min.
[0055] In a preferred embodiment, in S4, the spin coating conditions are: rotation speed 1200-1800 rad / min, time 20-40 s; the annealing temperature is 60-70℃, time 30-50 s, and the atmosphere is air.
[0056] The second aspect of the present invention provides a single-crystal perovskite thin film prepared by the method described in the first aspect.
[0057] Example 1
[0058] This embodiment relates to a method for rapidly growing single-crystal perovskite thin films, comprising the following steps:
[0059] (1) Take a 1cm×1cm sapphire substrate with a 1° offset angle (C plane biased towards A plane), place it in a tube furnace, and anneal it at 1100℃ for 10 hours in an air atmosphere to make parallel steps appear on the surface. Figure 2 The AFM topography of its surface steps is shown.
[0060] (2) Dissolve 576 mg BiI3 and 372 mg CsI in 2 mL DMSO (dimethyl sulfoxide) and stir on a stirrer at 50 °C until completely dissolved to obtain Cs3Bi2I9 precursor solution.
[0061] (3) Take 195uL of the precursor solution from step (2), add 130uL of valeric acid to it, shake well, and then centrifuge at 8000 rad / min for 10 min to obtain the final solution required for the synthesis material.
[0062] (4) Place the substrate obtained in step (1) on a spin coater, take 50 μL of the final solution from step (3) and spin coat it onto the substrate at a parameter of 1500 rad / min. Then immediately place the substrate on a heating stage for annealing (temperature 65℃). As the solvent evaporates rapidly until completely dry (30-50s), a Cs3Bi2I9 single crystal thin film can be obtained. The single crystal growth process is as follows: Figure 3 As shown in the figure, it can be seen that the nanosheets nucleate and begin epitaxial growth at 30s, the continuous growth and fusion of the nanosheets can be clearly seen at 45s, and the material growth is completed at 50s, and the nanosheets in the corresponding red dashed box seamlessly fuse into a larger single crystal.
[0063] Figure 4The image shown is an optical microscope image of the Cs3Bi2I9 single-crystal thin film synthesized in Example 1. The inset shows the electron scattering diffraction (EBSD) characterization within the red dashed box, and the single red color confirms its single-crystal nature. Figure 5 The image shows the Raman mapping of the Cs3Bi2I9 single-crystal thin film synthesized in Example 1, confirming the high uniformity of the film. The inset shows the Raman characteristic peaks.
[0064] Figure 6 The image shows the XRD pattern of the Cs3Bi2I9 single-crystal thin film synthesized in Example 1, confirming the high-quality crystal structure of the Cs3Bi2I9 single-crystal thin film.
[0065] Example 2
[0066] The difference between this embodiment and Embodiment 1 is that the precursors BiI3 and CsI are replaced with BiBr3 and CsBr, respectively, while other steps and parameters remain unchanged, resulting in a Cs3Bi2Br9 single-crystal thin film. Figure 7 This is a microscope image of a Cs3Bi2Br9 single-crystal thin film. Figure 8 Raman spectroscopy features of Cs3Bi2Br9 single-crystal thin films.
[0067] Example 3
[0068] The difference between this embodiment and Embodiment 1 is that the precursors BiI3 and CsI are replaced with SbBr3 and CsBr, respectively, while other steps and parameters remain unchanged, resulting in a Cs3Sb2Br9 single-crystal thin film. Figure 9 This is a microscope image of a Cs3Sb2Br9 single-crystal thin film. Figure 10 Raman spectroscopy pattern of Cs3Sb2Br9 single crystal thin film.
[0069] Example 4
[0070] The difference between this embodiment and Embodiment 1 is that the precursors BiI3 and CsI are replaced with BiI3 and MAI, respectively, while other steps and parameters remain unchanged, resulting in an MA3Bi2I9 single-crystal thin film. Figure 11 This is a microscope image of a MA3Bi2I9 single-crystal thin film. Figure 12 Raman spectroscopy features of MA3Bi2I9 single-crystal thin films.
[0071] Comparative Example 1
[0072] The difference between this comparative example and Example 1 is that the sapphire substrate was not miscut, while other steps and parameters remained unchanged, to prepare the Cs3Bi2I9 thin film. The resulting Cs3Bi2I9 thin film micrograph is shown below. Figure 13 As shown, the obtained nanosheets have inconsistent orientations, and when nanosheets with inconsistent orientations are fused, grain boundaries can be clearly observed (red dashed circle part).
[0073] Comparative Example 2
[0074] The difference between this comparative example and Example 1 is that the sapphire substrate was not annealed, while other steps and parameters remained unchanged to prepare the Cs3Bi2I9 thin film. The resulting Cs3Bi2I9 thin film micrograph is shown below. Figure 14 As shown, the obtained nanosheets have inconsistent orientations, and obvious inhomogeneities and grain boundaries can be clearly observed when the nanosheets are fused.
[0075] In summary, this invention employs a "co-orientation-driven fusion" growth technique, which guides perovskite nanosheets to undergo epitaxial nucleation and directional fusion on a staggered sapphire substrate. This successfully enables the fabrication of millimeter-scale high-quality perovskite single-crystal thin films within one minute, significantly shortening the synthesis time and making its large-scale preparation and practical application prospects promising. Furthermore, it eliminates the need for complex vapor deposition equipment, achieving high-quality epitaxial growth through simple solution processing and substrate pretreatment. This provides a lower-cost and more universal path for the integration of perovskite with mainstream semiconductor processes.
[0076] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.
Claims
1. A method for rapidly growing single-crystal perovskite thin films, characterized in that, Includes the following steps: S1. Anneal the sapphire substrate with C-plane offset from A-plane by 1-2° to obtain a substrate with parallel steps. S2. Mix and stir AX3, BX and organic solvent to obtain B3A2X9 precursor solution; Among them, A is selected from Bi and Sb; B is selected from Cs and MA; and X is selected from I and Br. S3. Take the B3A2X9 precursor solution, add a surfactant, and mix to obtain a spin-coating solution; S4. Spin-coating the spin-coating solution onto the surface of the substrate and annealing it to obtain a single-crystal perovskite thin film.
2. The method for rapidly growing single-crystal perovskite thin films as described in claim 1, characterized in that, In S1, the annealing treatment is carried out at a temperature of 1100-1200℃ for 8-10 hours in an air atmosphere.
3. The method for rapidly growing single-crystal perovskite thin films as described in claim 1, characterized in that, In S2, the molar ratio of AX3 to BX is 2:(2.5-3.5). And / or, the concentration of AX3 is 0.4-0.5M.
4. The method for rapidly growing single-crystal perovskite thin films as described in claim 1, characterized in that, In S2, the stirring temperature is 45-55℃.
5. The method for rapidly growing single-crystal perovskite thin films as described in claim 1, characterized in that, In S3, the volume ratio of the B3A2X9 precursor solution to the surfactant is (1.2-1.8):
1.
6. The method for rapidly growing single-crystal perovskite thin films as described in claim 1, characterized in that, In S3, the surfactant is valeric acid.
7. The method for rapidly growing single-crystal perovskite thin films as described in claim 1, characterized in that, In S3, the conditions for the mixing treatment are: centrifugation speed of 7000-9000 rad / min and time of 10-20 min.
8. The method for rapidly growing single-crystal perovskite thin films as described in claim 1, characterized in that, In S4, the spin coating conditions are: rotation speed 1200-1800 rad / min, time 20-40 s.
9. The method for rapidly growing single-crystal perovskite thin films as described in claim 1, characterized in that, In S4, the annealing treatment is carried out at a temperature of 60-70°C for 30-50 seconds, and the atmosphere is air.
10. A single-crystal perovskite thin film prepared by the method of any one of claims 1-9.