Large-area perovskite micron sheet, preparation method thereof and multi-dimensional laser

Abstract

The invention relates to a large-area perovskite micron sheet, a preparation method thereof and a multi-dimensional laser, and the preparation method comprises the steps: mixing perovskite precursor powder and a solvent, and obtaining a perovskite precursor solution; the method comprises the following steps: placing a PDMS template on a substrate, placing one side, with a cylinder, of the PDMS template on the substrate, dropwise adding a perovskite precursor solution to enable the perovskite precursor solution to fill a nanoflow channel formed by the PDMS template and the substrate, pressurizing the PDMS template, and depositing to obtain a large-area perovskite micron sheet; protruding cylinders are arranged on the surface of one side of the PDMS template at intervals. According to the invention, the auxiliary growth of the anti-conventional PDMS template is adopted, the precursor solution and the anti-solvent can freely and efficiently flow among the areas through the mutually communicated areas among the cylindrical bulge arrays in the PDMS template, and a stable and sufficient environment is provided for the crystallization of the large-area perovskite micron sheet; the size of the prepared large-area perovskite micron sheet can reach a hundred-micron level, and the surface is flat and uniform.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic materials, and particularly to a large-area perovskite microplate, a preparation method thereof, and a multi-dimensional laser. Background Art

[0002] In recent years, the perovskite material system in a microcavity has become a research hotspot in the fields of optoelectronic materials and micro-nano optics. The low preparation cost, high absorption and luminescence efficiency have promoted the continuous development of research in the directions of lasers, LED light-emitting devices, and solar cells under this system. Especially for perovskite materials with Cs + ions, MA + , PEA + as cations and Cl - , Br - and other halogen elements as anions, they can form stable laser emission at room temperature and have extremely high application potential.

[0003] However, the micron-sized small samples and uneven polycrystalline growth have greatly affected the gain quality of the optical cavity and restricted further physical research and practical applications. Therefore, obtaining a large-area, homogeneous, and stable perovskite material in a microcavity has become an important topic for the development of practical optoelectronic technologies in the scientific research community and the industrial community.

[0004] Currently, considering the comprehensive cost and growth reproducibility in the field, perovskite microplates are mainly obtained by chemical vapor deposition and solution growth methods. Chemical vapor deposition tends to form micron-sized small perovskites in a low-concentration atmosphere and perovskite films with uneven thickness in a high-concentration atmosphere. Due to the high-reflectivity substrate that constitutes the microcavity, it is difficult to match the crystal phase and the crystal orientation of the sample crystallization, and the yield of large-area microplates in the transition state is low. When depositing a large-area sample on a substrate with a matching crystal orientation by chemical vapor deposition and then transferring it to the target substrate, it is easy to introduce fragmentation and damage to the sample, resulting in the splitting of the optical gain range in practical applications. The samples grown by the solution method have unclear boundaries and large morphological differences. Even if large-area microplates are grown, new laminations are likely to grow on the large microplates, affecting the sample quality.

[0005] Therefore, developing a growth method for large-area perovskite microplates is of great significance for physical research and practical optoelectronic material applications. Summary of the Invention

[0006] To solve the above technical problems, the purpose of the present invention is to provide a large-area perovskite microplate, a preparation method thereof, and a multi-dimensional laser. The large-area perovskite microplate provided by the present invention has a homogeneous, complete, and undamaged surface and a large area. Through the assisted growth of an unconventional PDMS soft template, the material growth process is precisely controlled, thereby realizing the controllable synthesis of large-area samples and applying them to the construction of multi-dimensional lasers.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing large-area perovskite micro-sheets, and the preparation method includes the following steps:

[0009] Mix the perovskite precursor powder with a solvent to obtain a perovskite precursor solution;

[0010] Place the side of the PDMS template with cylinders on a substrate, drop the perovskite precursor solution, so that the perovskite precursor solution fills the nanofluidic channels formed by the PDMS template and the substrate, pressurize the PDMS template, and obtain the large-area perovskite micro-sheets through deposition; the surfaces of one side of the PDMS template have protruding cylinders arranged at intervals.

[0011] Traditional template-assisted growth is to transfer the pattern of the PDMS template onto the sample. For example, PDMS round holes are used to grow cylindrical samples, and strip holes are used to grow strip samples. Each hole crystallizes slowly independently, and is suitable for small-scale micron-level array samples. When used for growing large-area samples, the edge state of the material is unstable, prone to a large amount of fragmentation, and the regions are not connected. The anti-solvent penetrates slowly, and the crystallization efficiency decreases sharply with the increase in size.

[0012] The present invention adopts an unconventional PDMS template-assisted growth. The template-assisted direct growth avoids the fragmentation or inclination that may be brought about during the transfer process of large-area samples. Through the interconnected regions between the cylindrical protrusion arrays in the PDMS template, on the one hand, it provides a stable and sufficient solvent-anti-solvent action environment for the growth of large-area perovskite micro-sheets. The precursor solution and the anti-solvent can flow freely and efficiently between various regions, providing a stable and sufficient environment for the crystallization of large-area perovskite micro-sheets; on the other hand, the superposition of cylindrical protrusions with different diameters generates more boundary states, providing crystallization sites, and can provide an advantageous environment for the synthesis of samples in a specific size range. Multiple boundaries also ensure the rapid and uniform infiltration of the precursor solution, accelerating the production cycle.

[0013] The height of the cylindrical array limits the growth height of the material, inhibits the generation of multi-layer crystallization, and keeps the material at a uniform thickness. The multi-boundary template design provides more crystallization sites, providing an advantageous environment for the growth of large-area micro-sheets in a wide size range. It brings a feasible solution and efficiency optimization for the construction of large-area perovskite micro-sheet microcavities and the practical application of multi-dimensional lasers.

[0014] The present invention does not limit the specific type of the substrate, and all substrates used in traditional solution methods can be used, including but not limited to SiO 2 substrates, PET substrates, plexiglass substrates, etc.

[0015] The following are the preferred technical solutions of the present invention, but not a limitation to the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0016] Preferably, the diameter of the protruding cylinder of the PDMS template is 0.1 mm - 0.8 mm, for example, it can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm or 0.8 mm, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0017] Preferably, the height of the protruding cylinder of the PDMS template is 350 nm - 700 nm, for example, it can be 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm or 700 nm, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0018] Preferably, the PDMS template is composed of a combination of 1 - 5 kinds of PDMS sub - templates with different cylinder diameters. For example, it can be 1 kind, 2 kinds, 3 kinds, 4 kinds or 5 kinds, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable. Preferably, it is composed of a combination of 2 kinds of PDMS sub - templates with different diameters.

[0019] In the present invention, a PDMS template formed by splicing cylinder structures with at least 2 kinds of diameters is adopted. The combination of more than two cylinder diameters can provide different inter - column spacings, covering more large - area sample advantageous growth environmental conditions, improving the growth consistency and productivity. In addition, in a single large - size template, due to the limited mass transfer in the central region, the crystallization rate may be reduced and the reaction may be incomplete. The combination of multiple - diameter templates can introduce more boundary regions, promote the penetration of the anti - solvent, thereby enhancing the crystallization process, and at the same time provide more boundary sites, which is beneficial to uniform nucleation and growth, further optimizing the quality and yield of perovskite micro - sheets.

[0020] Preferably, the central - axis spacing of the protruding cylinders of the PDMS template is 0.8 mm - 1.2 mm, for example, it can be 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm or 1.2 mm, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0021] Preferably, the ratio of the diameter of the relatively large cylinder to the diameter of the relatively small cylinder ≤ 3. For example, it can be: the combination of a diameter of 0.1 mm and a diameter of 0.15 mm, the combination of a diameter of 0.1 mm and a diameter of 0.3 mm, the combination of a diameter of 0.3 mm and a diameter of 0.5 mm, the combination of a diameter of 0.5 mm and a diameter of 0.8 mm, etc.

[0022] In the present invention, by further optimizing the spacing between the protruding cylinders of the PDMS template to be 0.8 mm - 1.2 mm, and at the same time ensuring that the relative ratio of the different diameters of the protruding cylinders of the PDMS template ≤ 3, it is possible to improve the crystal growth rate while ensuring the uniformity and morphological integrity of the crystal, making the quality of the prepared large-area perovskite micro-sheets higher. If the spacing between the central axes of the protruding cylinders is too large, the PDMS template may collapse due to insufficient support, resulting in uneven growth height of the sample and the formation of multiple layers of crystals, affecting its quality and consistency; if the spacing between the central axes of the protruding cylinders is too small, the growth area of the sample is limited, and it is easy to contact the cylinders during the crystallization process, increasing the risk of damaging the sample when peeling off the template and affecting the integrity of the material. Moreover, if the relative ratio of the different diameters of the cylinders is greater than 3, the dominant growth environment interval covered by the template becomes narrow and discontinuous, resulting in obvious differences in the samples grown on the same substrate, uneven size and morphology distribution, and thus significantly reducing the repeatability and stability of the growth process.

[0023] Preferably, the area of the PDMS sub-template is (0.2 - 1) cm × (0.2 - 1) cm. For example, it can be 0.2 cm × 0.2 cm, 0.3 cm × 0.3 cm, 0.4 cm × 0.4 cm, 0.5 cm × 0.5 cm, 0.6 cm × 0.6 cm, 0.7 cm × 0.7 cm, 0.8 cm × 0.8 cm, 0.9 cm × 0.9 cm, 0.2 cm × 0.4 cm, 0.25 cm × 0.5 cm, 0.3 cm × 0.6 cm, 0.35 cm × 0.7 cm, 0.4 cm × 0.8 cm, 0.45 cm × 0.9 cm or 0.5 cm × 1 cm, but not limited to the listed values. Other unlisted values within the numerical range are equally applicable, and preferably (0.6 - 0.8) cm × (0.3 - 0.4) cm.

[0024] Preferably, the perovskite precursor powder is configured according to the stoichiometric ratio, and the stoichiometric ratio is determined by the chemical formula of the target perovskite material.

[0025] Preferably, the solvent includes dimethyl sulfoxide (DMSO) and / or N,N-dimethylformamide (DMF).

[0026] Preferably, before obtaining the perovskite precursor solution, supersaturation treatment and dilution steps are also included.

[0027] Before obtaining the perovskite precursor solution, the present invention also includes performing supersaturation treatment. Before obtaining the perovskite precursor solution, the present invention also includes performing supersaturation treatment. On the one hand, it is to optimize the chemical ratio and improve the purity of the target product. The supersaturation treatment helps to correct the chemical composition of the crystalline product during the deposition process, making the obtained perovskite material closer to the target chemical formula, while reducing the formation of polymers or complexes, thereby improving the purity and crystallization quality of the product. On the other hand, it can improve solubility control and achieve uniform precipitation. After the supersaturation treatment, the added antisolvent is the same as the antisolvent used in the subsequent solution growth process, which enables the solubility to decrease uniformly during the deposition process, ensuring uniform precipitation of the sample and obtaining more uniform and high-purity perovskite microplates.

[0028] If the supersaturation treatment is not performed and only a perovskite precursor solution with a specific concentration is prepared, during the subsequent deposition and crystallization process, due to the different dissolution rates and solubilities of the two precursors in the solvent, the first-precipitated crystal may be one of the precursor powders, rather than the target product. After a period of time, the target crystal can be obtained. This may lead to the possible residue of non-perovskite phases with similar colors in the product, increasing the risk of misjudgment in practical applications. The non-perovskite crystals precipitated first will reduce the purity of the microplates and make their surface uniformity worse, thereby affecting the device performance and subsequent applications.

[0029] Preferably, the operation steps of the supersaturation treatment are as follows: After mixing the perovskite precursor powder with the solvent, heat and stir until completely dissolved, add the antisolvent until powder precipitates, and filter to obtain a saturated solution.

[0030] Preferably, the determination basis for the completion of the supersaturation treatment is that equal amounts of powder precipitate each time an equal amount of antisolvent is added.

[0031] In the present invention, during the supersaturation treatment process, an equal amount of antisolvent is added each time, thereby reducing the solubility of the perovskite precursor in the solvent and enabling it to deposit and crystallize.

[0032] Preferably, the antisolvent includes acetonitrile and / or toluene.

[0033] Preferably, the mixing volume ratio of the saturated solution to the solvent in the dilution step is 1:(0.1 - 50), for example, it can be 1:0.1, 1:0.2, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:10, 1:20, 1:30, 1:40, or 1:50, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable, and preferably 1:(0.3 - 4).

[0034] Preferably, the concentration of the perovskite precursor solution obtained after the dilution operation is 0.01 mmol / mL - 0.50 mmol / mL. For example, it can be 0.01 mmol / mL, 0.05 mmol / mL, 0.10 mmol / mL, 0.15 mmol / mL, 0.20 mmol / mL, 0.25 mmol / mL, 0.30 mmol / mL, 0.35 mmol / mL, 0.40 mmol / mL, 0.45 mmol / mL, or 0.50 mmol / mL. However, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable. Preferably, it is 0.05 mmol / mL - 0.30 mmol / mL.

[0035] In the present invention, by further controlling the concentration of the perovskite precursor solution to be 0.01 mmol / mL - 0.50 mmol / mL, the crystal precipitation rate during the deposition process can be controlled. If the concentration of the perovskite precursor solution is too high, the crystallization rate will be too fast, and dense microcrystals will be rapidly generated during the precursor dropping stage, making it difficult to grow large-area micron sheets. If the concentration of the perovskite precursor solution is too low, the required growth period will be too long, and the yield of high-quality micron sheets will be relatively low.

[0036] Preferably, the pressure for pressurization is 0.1 N / cm 2 - 5 N / cm 2 , for example, it can be 0.1 N / cm 2 , 0.2 N / cm 2 , 0.3 N / cm 2 , 0.4 N / cm 2 , 0.5 N / cm 2 , 0.6 N / cm 2 , 0.7 N / cm 2 , 0.8 N / cm 2 , 0.9 N / cm 2 , 1.0 N / cm 2 , 1.5 N / cm 2 , 2.0 N / cm 2 , 2.5 N / cm 2 , 3.0 N / cm 2 , 3.5 N / cm 2 , 4.0 N / cm 2 , 4.5 N / cm 2 or 5 N / cm 2 , but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0037] In the present invention, by applying a pressure of 0.1 N / cm 2 - 5 N / cm 2The pressure ensures the tight combination of the template and the substrate, while maintaining the stability of the growth device and reducing structural disturbances.

[0038] Preferably, the pressure holding time of the pressurization is 1 h - 3 h. For example, it can be 1 h, 1.5 h, 2 h, 2.5 h or 3 h, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0039] Preferably, the preparation method of the PDMS template includes: fabricating a silicon template with cylindrically shaped holes arranged at intervals by photolithography; mixing a PDMS precursor and a curing agent in a ratio of (10 - 9):1 and pouring the mixture onto the silicon template that has been subjected to hydrophobic treatment; performing vacuum treatment, heating and curing, and peeling to obtain the PDMS template.

[0040] In the present invention, a silicon template with cylindrically shaped holes arranged at intervals is used during the preparation of the PDMS template, so as to enable the prepared template to have a periodically arranged convex cylindrical structure.

[0041] Preferably, the deposition is carried out in an atmosphere of an anti-solvent, and the type of the anti-solvent in the atmosphere is the same as that used in the supersaturation treatment stage.

[0042] Preferably, the deposition is carried out in a semi-closed device with an anti-solvent.

[0043] Preferably, heating is carried out during the deposition process.

[0044] Preferably, the heating is divided into a first-stage heating and a second-stage heating.

[0045] Preferably, the temperature of the first-stage heating is 45 °C - 60 °C. For example, it can be 45 °C, 50 °C, 55 °C or 60 °C, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0046] Preferably, the time of the first-stage heating is 20 min - 30 min. For example, it can be 20 min, 22 min, 24 min, 25 min, 26 min, 28 min or 30 min, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0047] Preferably, the temperature of the second-stage heating is 25 °C - 35 °C. For example, it can be 25 °C, 28 °C, 30 °C or 35 °C, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0048] Preferably, the heating time in the second stage is 20h - 30h. For example, it can be 20h, 22h, 24h, 25h, 26h, 28h, or 30h, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0049] In the present invention, the system composed of the PDMS template, the perovskite precursor solution, and the substrate is placed as a whole into a semi-closed device with an anti-solvent solution. Meanwhile, by heating, the semi-closed device is filled with anti-solvent gas. On the one hand, the stable anti-solvent atmosphere can continuously and controllably reduce the solubility of the precursor solution in the perovskite, achieving uniform crystal growth, obtaining high-quality large-area perovskite micro-sheets without damage. Combining the design of the template period, precursor concentration, and pressure, the material growth process is precisely controlled, thereby realizing the synthesis of controllable large-area samples.

[0050] On the other hand, the present invention adopts a two-stage heating process to control the crystal precipitation rate. In the first stage, a higher temperature is used to accelerate the volatilization of the anti-solvent, enabling it to quickly fill the entire container, thereby providing a stable anti-solvent atmosphere environment for crystal growth. Meanwhile, the high temperature promotes the rapid precipitation of perovskite crystals in the edge region, forming initial crystallization nuclei, effectively increasing the nucleation density, and ensuring a high yield.

[0051] In the second stage, by reducing the heating temperature and combining with the reserved air holes, the concentration of the anti-solvent atmosphere in the container is kept uniform, thereby ensuring the uniform growth of crystals throughout the sample area. In addition, in an anti-solvent atmosphere environment with a lower concentration, the crystal growth rate slows down, enabling the perovskite micro-sheets to grow more uniformly, reducing grain boundary defects, and improving the crystallization quality and device performance.

[0052] As a preferred technical solution of the preparation method of the present invention, the preparation method includes the following steps:

[0053] S1: Prepare the perovskite precursor solution. The perovskite component is ABX 3 . Optionally, the A component includes Cs + , MA + , PEA + ions, or a combination of one or more of them. The B component mainly uses Pb 2+ ions in the target functional design. The X component includes Cl - , Br - ions, or any combination of one or more of them.

[0054] Take 1 mmol of AX and BX each 2The precursor powder is fully mixed on a weighing paper and then dissolved in 2.5 ml of a solvent, which includes DMSO and / or DMF. Then, it is heated and continuously stirred while adding an anti-solvent until obvious powder precipitation occurs, and a saturated solution is obtained by filtration. The heating temperature is adjusted according to the difference of the precursor and the room temperature in actual operation. For example, it can be 30 °C, 40 °C or 50 °C. The stirring rate is 500 rpm - 1000 rpm. For example, it can be 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm or 1000 rpm.

[0055] The saturated solution and the solvent are mixed and diluted at a volume ratio of 1:(0.1 - 50), and after stirring, a perovskite precursor solution with a concentration of 0.01 mmol / mL - 0.50 mmol / mL is obtained.

[0056] S2: Prepare the PDMS template and perform selective area cutting. The hole diameter on the silicon master template is 0.1 mm - 0.8 mm, the depth is 350 nm - 700 nm, and the period is 0.8 mm - 1.2 mm. Multiple holes with different diameters can be lithographed on one template at the same time, and the depth is configured according to requirements; after the silicon template is subjected to hydrophobic treatment, the PDMS precursor and the curing agent are fully mixed at a ratio of 10:1 and then poured on the hydrophobic-treated silicon template; after vacuum treatment for 2 h, it is heated and cured at 30 °C - 150 °C for 10 min - 24 h. The heating temperature and time are selected according to requirements, and then peeled off to obtain a PDMS template with a flat surface and fewer bubbles. The PDMS template has a cylindrical protrusion array corresponding to the hole period on the silicon master template.

[0057] The large PDMS template is cut into PDMS sub-templates of 0.7 cm × 0.35 cm. Optionally, the substrate is first subjected to oxygen Plasma surface hydrophilic treatment. Two PDMS sub-templates with different cylindrical diameter protrusion periods are placed side by side and closely attached to the substrate. The diameter selection is configured according to requirements, and the difference ≤ 3 times. For example, it can be: 0.1 mm diameter and 0.15 mm diameter, 0.1 mm diameter and 0.3 mm diameter, 0.3 mm diameter and 0.5 mm diameter, 0.5 mm diameter and 0.8 mm diameter, etc.

[0058] S3: Drop 5 μL - 15 μL of the perovskite precursor solution, and apply a pressure of 0.1 N / cm 2 - 5 N / cm 2 to the PDMS template and keep the pressure for 1 h - 3 h, and then remove the pressure. At this time, the template and the substrate are tightly combined, and the sample is initially crystallized. After removing the pressure, the stability of the growth device can be maintained, and structural disturbances can be reduced.

[0059] S4: The system composed of the PDMS template, precursor solution and substrate is placed as a whole into a beaker with a volume of 50 mL - 200 mL containing an anti-solvent solution. After sealing, 4 - 10 holes with a diameter of 1 mm - 3 mm are punched and placed on a hot stage. The anti-solvent selected should correspond to the precursor solvent and act as a poor solvent for the precursor to promote the precipitation and crystallization of the material. The optional dosage of the anti-solvent should be 3 mL - 10 mL.

[0060] S5: The beaker is placed on the hot stage for heating deposition. The first-stage heating at 45°C - 60°C lasts for 20 min - 30 min to quickly fill the growth environment with anti-solvent vapor. The second-stage heating at 25°C - 35°C lasts for 20 h - 30 h to slowly evaporate the anti-solvent vapor, balance the hole loss, and provide a stable atmosphere environment for growth. After heating, the PDMS template is removed to obtain large-area perovskite micro-sheets.

[0061] In a second aspect, the present invention provides a large-area perovskite micro-sheet, which is prepared according to the preparation method described in the first aspect.

[0062] The size of the large-area perovskite micro-sheet is (100 - 350) μm × (100 - 350) μm. For example, it can be 100 μm × 100 μm, 100 μm × 200 μm, 250 μm × 100 μm, 100 μm × 150 μm, 200 μm × 200 μm, 250 μm × 250 μm, 300 μm × 300 μm, 200 μm × 300 μm, 200 μm × 350 μm, 250 μm × 350 μm or 350 μm × 350 μm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0063] The large-area perovskite micro-sheet provided by the present invention has a larger area, a more uniform surface, no defects and higher quality compared with the existing perovskite sheets, and is the perovskite micro-sheet with the most excellent morphology and performance reported so far.

[0064] In a third aspect, the present invention provides a large-area perovskite micro-sheet microcavity, which includes the large-area perovskite micro-sheet described in the second aspect.

[0065] The large-area perovskite micro-sheet microcavity provided by the present invention meets the urgent need for a uniform and stable large-area perovskite material in the microcavity.

[0066] In a fourth aspect, the present invention provides a multi-dimensional laser, which includes the large-area perovskite micro-sheet microcavity described in the third aspect.

[0067] The large-area perovskite micro-sheet microcavity of the present invention is excited by femtosecond pulses to generate a new type of laser with multi-dimensional information, realizing related applications.

[0068] The numerical ranges described in the present invention not only include the above-listed point values, but also any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the described ranges.

[0069] Compared with the prior art, the present invention has at least the following beneficial effects:

[0070] (1) The size of the large-area perovskite microplates provided by the present invention can reach the order of hundreds of micrometers, with a flat and uniform surface and no optical defects during the long-range signal conduction process.

[0071] (2) The large-area perovskite microplates provided by the present invention adopt unconventional template confinement means. By designing a microcolumn array to support the space between the template and the substrate, on the one hand, the precursor solution and the antisolvent can flow freely and efficiently between regions, providing a stable and sufficient environment for the crystallization of large-area microplates. On the other hand, the superposition of protrusions with different cylinder diameters generates more edge states, providing crystallization sites and being able to provide an advantageous environment for the synthesis of samples in a specific size range. The multiple boundaries also ensure the rapid and uniform infiltration of the precursor solution, accelerating the production cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 is a top view of the PDMS template in Example 1 of the present invention, where 1 represents the substrate, 2 represents the protruding cylinders, 21 and 22 represent cylinders with different diameters, 3 represents the perovskite precursor solution, and 4 represents the pressure module;

[0073] Figure 2 is a side view of the PDMS template in Example 1 of the present invention;

[0074] Figure 3 is a schematic diagram of the periodic design of the silicon master template prepared in Example 1 of the present invention;

[0075] Figure 4 is an optical micrograph of the large-area perovskite microplate prepared in Example 1 of the present invention;

[0076] Figure 5 is a thickness measurement diagram of the large-area perovskite microplate prepared in Example 1 of the present invention;

[0077] Figure 6 is a multi-dimensional laser spectrum with angle information of the large-area perovskite microplate prepared in Example 1 of the present invention;

[0078] Figure 7 is a perovskite microplate prepared by the solution method in Comparative Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0079] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and through specific embodiments. However, the following examples are merely simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0080] In the following examples and comparative examples, unless otherwise specified, all reagents and consumables are purchased from conventional reagent manufacturers in the art; unless otherwise specified, the experimental methods and technical means used are conventional methods and means in the art.

[0081] The preparation methods of the silicon master template and the PDMS template used in the following examples are as follows. PDMS templates with different cylinder diameters, heights, spacings, and combination numbers can be selected according to needs:

[0082] The physical mask used in the photolithography of the silicon master template is as Figure 3 shown; the hole diameter on the silicon master template is 0.1 mm - 0.8 mm, the depth is 350 nm - 700 nm, and the period is 0.8 mm - 1.2 mm. Multiple holes with different diameters can be lithographed on one template at the same time, and the depth can be configured according to requirements. After the silicon template is subjected to hydrophobic treatment, the PDMS precursor and the curing agent are fully mixed in a ratio of 10:1 and poured on the hydrophobic-treated silicon template. After vacuum treatment for 2 h, it is heated and cured at 30°C - 150°C for 10 min - 24 h. The heating temperature and time are selected according to requirements. Then, it is peeled off to obtain a PDMS template with a flat surface and fewer bubbles. The PDMS template has a cylindrical protrusion array corresponding to the hole period on the silicon master template.

[0083] The large PDMS template is cut into PDMS sub-templates of 0.7 cm × 0.35 cm. Optionally, the substrate is first subjected to oxygen Plasma surface hydrophilic treatment.

[0084] Example 1

[0085] This example provides a large-area perovskite microplate. The preparation method of the large-area perovskite microplate provided in this example includes the following steps. The top view and side view of the PDMS template are respectively as Figure 1 and Figure 2 shown:

[0086] S1: Take 212 mg of CsBr and 367 mg of PbBr 2The precursor powder was fully mixed on a weighing paper and then dissolved in 2.5 ml of DMSO solvent. It was continuously stirred at 40 °C and 500 rpm, and acetonitrile was added until obvious precipitation of powder occurred. When an equal amount of the anti-solvent acetonitrile was added and an equal amount of powder was precipitated, the precipitate was filtered off to obtain a saturated solution. The saturated solution was mixed and diluted with DMSO solvent at a volume ratio of 1:0.3, and after stirring, a perovskite precursor solution with a concentration of 0.4 mmol / mL was obtained.

[0087] S2: Select sub-templates (21) with a cut cylindrical height of 500 nm, a diameter of 0.3 mm, and a cylindrical central axis spacing of 1.0 mm and sub-templates (22) with a diameter of 0.4 mm and a cylindrical central axis spacing of 1.0 mm and place them closely together. Place the side of the combined PDMS template 2 with cylinders on the SiO 2 substrate 1.

[0088] S3: Drop 10 μl of CsPbBr 3 perovskite precursor solution 3, apply a pressure of 0.3 N / cm 2 to the PDMS template and keep the pressure for 2 h, then remove the pressure.

[0089] S4: Place the system composed of the PDMS template, CsPbBr 3 perovskite precursor solution and SiO 2 substrate as a whole into a 100 mL beaker containing 4 ml of acetonitrile solution, seal it, and punch 6 holes with a diameter of 1 mm and place it on a hot plate.

[0090] S5: Place the beaker on the hot plate for heating deposition. The first-stage heating at 45 °C is for 20 min to quickly fill the growth environment with anti-solvent vapor, and the second-stage heating at 35 °C is for 24 h to slowly form acetonitrile vapor to provide a stable atmosphere environment for growth. After heating is completed, remove the PDMS template to obtain large-area perovskite micro-sheets.

[0091] The optical micrograph of the prepared large-area perovskite micro-sheets is as Figure 4 shown. It can be seen from Figure 4 that the perovskite micro-sheets with an area of 200 μm × 90 μm have clear boundaries and regular morphologies, showing excellent crystallization quality. In addition, the uniform optical properties indicate that there are no obvious cracks or non-perovskite phases generated inside the crystal, demonstrating the effectiveness of the method of the present invention in preparing high-quality and large-area perovskite micro-sheets.

[0092] The thickness test of the prepared large-area perovskite micro-sheets is as Figure 5As shown, based on the method for preparing large-area perovskite microplates described above, a perovskite microplate microcavity with large area, uniform stability and no optical defects is formed. The thickness measurement shows that it is about 450 nm, and the sample thickness is controlled within the height of the cylinder, which is 500 nm.

[0093] Example 2

[0094] This example provides a large-area perovskite microplate. The preparation method of the large-area perovskite microplate provided in this example includes the following steps:

[0095] S1: Take 212 mg of CsBr and 400 mg of PbBr 2 precursor powder. After fully mixing on the weighing paper, dissolve it in 2.5 ml of DMF solvent. Stir continuously at 40 °C and 500 rpm and add toluene until obvious powder precipitation occurs. When an equal amount of anti-solvent toluene is added and an equal amount of powder precipitates, filter to remove the precipitate to obtain a saturated solution. The saturated solution is mixed and diluted with DMF solvent at a volume ratio of 1:4, and after stirring, a perovskite precursor solution with a concentration of 0.1 mmol / mL is obtained.

[0096] S2: Select sub-templates with a cut cylinder height of 550 nm, a diameter of 0.4 mm, and a cylinder central axis spacing of 0.8 mm, a sub-template with a diameter of 0.5 mm and a cylinder central axis spacing of 0.8 mm, and a sub-template with a diameter of 0.6 mm and a cylinder central axis spacing of 0.8 mm. Press the three PDMS sub-templates tightly together, and place the side of the combined PDMS template with the cylinder on the SiO 2 substrate.

[0097] S3: Drop 12 μl of CsPbBr 3 perovskite precursor solution, apply a pressure of 0.1 N / cm 2 to the PDMS template and keep the pressure for 3 h, then remove the pressure.

[0098] S4: Place the system composed of the PDMS template, CsPbBr 3 perovskite precursor solution and SiO 2 substrate as a whole into a 100 mL beaker with 3 ml of toluene solution. After sealing, make 6 holes with a diameter of 1 mm and place it on the hot stage.

[0099] S5: Place the beaker on the hot stage for heating deposition. The first-stage heating at 50 °C is for 30 min to quickly fill the growth environment with anti-solvent vapor, and the second-stage heating at 30 °C is for 24 h to slowly form toluene vapor to provide a stable atmosphere environment for growth. After heating, remove the PDMS template to obtain a large-area perovskite microplate.

[0100] Example 3

[0101] This embodiment provides a large-area perovskite microplate. The preparation method of the large-area perovskite microplate provided in this embodiment includes the following steps:

[0102] S1: Take 260 mg of CsI and 461 mg of PbI 2 precursor powder. After fully mixing on a weighing paper, dissolve it in 2.5 ml of DMSO solvent. Stir continuously at 40 °C and 500 rpm and add acetonitrile until obvious powder precipitation occurs. When the same amount of powder precipitates after adding an equal amount of acetonitrile antisolvent, filter to remove the precipitate to obtain a saturated solution. The saturated solution and DMSO solvent are mixed and diluted according to a volume ratio of 1:1, and after stirring, a perovskite precursor solution with a concentration of 0.25 mmol / mL is obtained.

[0103] S2: Select a sub-template with a cut cylindrical height of 650 nm, a diameter of 0.6 mm, and a cylindrical central axis interval of 1.2 mm and a sub-template with a diameter of 0.8 mm and a cylindrical central axis interval of 1.2 mm and stick them closely. Place the side of the combined PDMS template with the cylinder on the PET substrate.

[0104] S3: Drop 8 μl of CsPbI 3 perovskite precursor solution, apply a pressure of 0.5 N / cm 2 and keep the pressure for 1 h, then remove the pressure.

[0105] S4: Put the system composed of the PDMS template, CsPbI 3 perovskite precursor solution and PET substrate into a 200 mL beaker with 4 ml of acetonitrile solution. Seal it and punch 6 holes with a diameter of 1 mm and place it on a hot plate.

[0106] S5: Place the beaker on the hot plate for heating deposition. The first-stage heating at 60 °C is for 20 min to quickly fill the growth environment with antisolvent vapor, and the second-stage heating at 25 °C is for 30 h to slowly form acetonitrile vapor to provide a stable atmosphere environment for growth. After the heating is completed, remove the PDMS template to obtain a large-area perovskite microplate.

[0107] Example 4

[0108] This embodiment provides a large-area perovskite microplate. The difference from Example 1 is only that when preparing this large-area perovskite microplate, the sub-template with a cylindrical diameter of 0.3 mm in the PDMS template is replaced with a sub-template with a cylindrical diameter of 0.4 mm with the same area, that is, the PDMS template only contains one cylindrical diameter.

[0109] Example 5

[0110] This embodiment provides a large-area perovskite microplate, which is only different from that of Embodiment 1 in that when preparing this large-area perovskite microplate, the interval between the central axes of the cylinders in the PDMS template is 0.55 mm.

[0111] Embodiment 6

[0112] This embodiment provides a large-area perovskite microplate, which is only different from that of Embodiment 1 in that when preparing this large-area perovskite microplate, the sub-template with a cylinder diameter of 0.3 mm in the PDMS template is replaced with a sub-template with a cylinder diameter of 0.1 mm of the same area, that is, the relative ratio between the different diameters of the protruding cylinders in the PDMS template is 4.

[0113] Embodiment 7

[0114] This embodiment provides a large-area perovskite microplate, which is only different from that of Embodiment 1 in that when preparing this large-area perovskite microplate, supersaturation treatment is not performed, and a perovskite precursor solution with a concentration of 0.4 mmol / mL is directly prepared.

[0115] Embodiment 8

[0116] This embodiment provides a large-area perovskite microplate, which is only different from that of Embodiment 1 in that when preparing this large-area perovskite microplate, only the first-stage heating is performed, and the total heating time is 50 min at 55 °C.

[0117] Embodiment 9

[0118] This embodiment provides a large-area perovskite microplate, which is only different from that of Embodiment 1 in that when preparing this large-area perovskite microplate, only the second-stage heating is performed, and the total heating time is 20 h at 25 °C.

[0119] Comparative Example 1

[0120] This comparative example provides a perovskite plate. When preparing this large-area perovskite microplate, CsPbBr perovskite microplates prepared by the traditional solution method are used. The processes of solution preparation, substrate treatment, and heating growth are basically the same as those of the embodiment, except that there is no specially designed template with cylindrical protrusions. 3 The prepared perovskite plate is as shown in. As can be seen from the figure, there are problems such as unclear edge states, growth of stacked layers, and small sample sizes in the samples grown by the solution method. This is due to the irregular crystallization sites on the single substrate, the recrystallization generated due to no limitation in the vertical direction, and the rapid reaction with the anti-solvent without template protection. After comparison, the preparation method of the large-area perovskite microplate described in the present invention has significant performance advantages.

[0121] The prepared perovskite plate is as Figure 7 shown. As can be seen from the figure, there are problems such as unclear edge states, growth of stacked layers, and small sample sizes in the samples grown by the solution method. This is due to the irregular crystallization sites on the single substrate, the recrystallization generated due to no limitation in the vertical direction, and the rapid reaction with the anti-solvent without template protection. After comparison, the preparation method of the large-area perovskite microplate described in the present invention has significant performance advantages.

[0122] Application Example 1

[0123] This application example provides a multi-dimensional laser, which is prepared by using the large-area perovskite micro-sheets in Example 1.

[0124] The multi-dimensional laser is excited by femtosecond pulses to generate a new type of laser with multi-dimensional information. The multi-dimensional laser spectrum with angular information is as Figure 6 shown. The large-area perovskite micro-sheets can provide a bearing space for the momentum conduction of light, and a new type of multi-dimensional laser with an additional momentum distribution can be obtained.

[0125] Testing method: The large-area perovskite micro-sheets prepared in the examples and comparative examples are tested, and the test results are shown in Table 1 below.

[0126] Table 1

[0127]

[0128]

[0129]

[0130] It can be seen from the test results that:

[0131] (1) It can be seen from Examples 1 - 3 that the present invention adopts the assisted growth of an unconventional PDMS template. The template-assisted direct growth avoids the fragmentation or inclination that may occur during the transfer of large-area samples. The size of the large-area perovskite micro-sheets prepared can reach the order of hundreds of micrometers, the surface is flat and uniform, and there are no optical defects during the long-range signal conduction process. Through the interconnected regions between the cylindrical protrusion arrays in the PDMS template of the present invention, the precursor solution and the antisolvent can flow freely and efficiently between various regions, providing a stable and sufficient environment for the crystallization of large-area perovskite micro-sheets; the superposition of cylindrical protrusions with different diameters generates more boundary states, provides crystallization sites, and can provide an advantageous environment for the synthesis of samples in a specific size range.

[0132] (2) By comparing Example 1 with Example 4, it can be seen that the present invention further adopts a PDMS template composed of at least 2 types of cylindrical structures spliced together. The combination of more than two cylindrical diameters can provide different inter-column spacings, covering more advantageous growth environment conditions for large-area samples, and improving the growth consistency and yield. In addition, in a single large-size template, due to the limited mass transfer in the central region, the crystallization rate may be reduced and the reaction may be incomplete. The combination of multiple-diameter templates can introduce more boundary regions, promote the penetration of the antisolvent, thereby enhancing the crystallization process, and at the same time provide more boundary sites, which is beneficial to uniform nucleation and growth, and further optimize the quality and yield of perovskite micro-sheets.

[0133] (3) It can be seen from the comparison between Example 1 and Examples 5 - 6 that by further optimizing the interval between the protruding cylinders of the PDMS template to be 0.8 mm - 1.2 mm and ensuring that the relative ratio of the different diameters of the protruding cylinders of the PDMS template ≤ 3, the present invention can improve the crystal growth rate while ensuring the uniformity of the crystal and the integrity of the morphology, resulting in higher quality of the prepared large-area perovskite micro-sheets. If the interval between the central axes of the protruding cylinders is too large, the PDMS template may collapse due to insufficient support, resulting in uneven growth height of the sample and the formation of multiple layers of crystals, affecting its quality and consistency. If the interval between the central axes of the protruding cylinders is too small, the available growth area of the sample is limited, and it is easy to contact the cylinders during the crystallization process, increasing the risk of damaging the sample when peeling off the template and affecting the integrity of the final sample. Moreover, if the relative ratio between the diameters of the cylinders is greater than 3, the dominant growth environment interval covered by the template becomes narrow and discontinuous, resulting in obvious differences in the samples grown on the same substrate, uneven size and morphology distribution, and thus significantly reducing the repeatability and stability of the growth process.

[0134] (4) It can be seen from the comparison between Example 1 and Example 7 that before obtaining the perovskite precursor solution, the present invention further includes performing supersaturation treatment. On the one hand, it is to optimize the chemical ratio and improve the purity of the target product. The supersaturation treatment helps to correct the chemical composition of the crystalline product during the deposition process, making the obtained perovskite material closer to the target chemical formula, while reducing the formation of polymers or complexes, thereby improving the purity and crystallization quality of the product. On the other hand, it can improve solubility control and achieve uniform precipitation. After the supersaturation treatment, the added antisolvent is the same as the antisolvent used in the subsequent solution growth process, which enables the solubility to decrease uniformly during the deposition process, ensuring uniform precipitation of the sample and obtaining more uniform and high-purity perovskite micro-sheets.

[0135] If no supersaturation treatment is performed and only a perovskite precursor solution with a specific concentration is prepared, during the subsequent deposition and crystallization process, due to the different dissolution rates and solubilities of the two precursors in the solvent, the first-precipitated crystal may be one of the precursor powders rather than the target product. After a period of time, the target crystal can be obtained. This may lead to the possible residual non-perovskite phases with similar colors in the product, increasing the risk of misjudgment in practical applications. The first-precipitated non-perovskite crystals will reduce the purity of the micro-sheets and make their surface uniformity worse, thereby affecting the device performance and subsequent applications.

[0136] (5) It can be seen from the comparison between Example 1 and Examples 8 - 9 that the present invention controls the crystal precipitation rate by adopting a two-stage heating process. In the first stage, a higher temperature is adopted to accelerate the volatilization of the antisolvent, enabling it to quickly fill the entire container, thereby providing a stable antisolvent atmosphere environment for crystal growth. Meanwhile, the high temperature promotes the rapid precipitation of perovskite crystals in the edge region, forming initial crystallization nuclei, effectively increasing the nucleation density, and ensuring a high yield.

[0137] In the second stage, by reducing the heating temperature and combining with the reserved air holes, the concentration of the antisolvent atmosphere inside the container is kept uniform, thereby ensuring the uniform growth of crystals in the entire sample area. In addition, in an antisolvent atmosphere environment with a lower concentration, the crystal growth rate slows down, enabling the perovskite microplates to grow more uniformly, reducing grain boundary defects, and improving the crystallization quality and device performance.

[0138] (6) It can be seen from the comparison between Example 1 and Comparative Example 1 that the samples grown by the traditional solution method have problems such as unclear edge states, growth of laminations, and smaller sample sizes. After comparison, the method for preparing large-area perovskite microplates described in the present invention has significant performance advantages.

[0139] In summary, the size of the large-area perovskite microplates prepared by the present invention can reach the order of hundreds of micrometers, with a flat and uniform surface and no optical defects during the long-range signal conduction process. The present invention adopts the assisted growth of an unconventional PDMS template. The template-assisted direct growth avoids the possible fragmentation or inclination during the transfer of large-area samples. Through the interconnected regions between the cylindrical protrusion arrays in the PDMS template, the precursor solution and the antisolvent can flow freely and efficiently between various regions, providing a stable and sufficient environment for the crystallization of large-area perovskite microplates; the superposition of cylindrical protrusions with different diameters generates more boundary states, providing crystallization sites, and being able to provide an advantageous environment for the synthesis of samples in a specific size range.

[0140] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for preparing large-area perovskite microsheets, characterized in that: The preparation method comprises the following steps: mixing a perovskite precursor powder and a solvent to obtain a perovskite precursor solution; The cylindrical side of the PDMS template is placed on the substrate, a perovskite precursor solution is added dropwise to fill the nanoflow channel formed by the PDMS template and the substrate, and the PDMS template is pressurized to obtain the large-area perovskite micron sheet through deposition; The surface of one side of the PDMS template has protruding cylinders arranged at intervals.

2. The preparation method according to claim 1, characterized in that: The diameter of the protruding cylinder of the PDMS template is 0.1 mm-0.8 mm, and the height is 350 nm-700 nm; Preferably, the PDMS template comprises a combination of PDMS sub-templates of 1 to 5 cylindrical diameters, preferably a combination of PDMS sub-templates of 2 diameters; Preferably, the center axis spacing of the cylinders protruding from the PDMS template is 0.8 mm to 1.2 mm, and the relative ratio of different diameters is ≤3; Preferably, the area of ​​the PDMS sub-template is (0.2-1) cm×(0.2-1) cm, preferably (0.6-0.8) cm×(0.3-0.4) cm.

3. The preparation method according to claim 1 or 2, characterized in that: The perovskite precursor powder is configured according to a stoichiometric ratio; Preferably, the solvent comprises dimethyl sulfoxide and / or N,N-dimethylformamide.

4. The preparation method according to any one of claims 1 to 3, characterized in that The method of obtaining the perovskite precursor solution also includes supersaturation treatment and dilution steps; Preferably, the supersaturation treatment comprises the following steps: mixing the perovskite precursor powder and the solvent, heating and stirring until they are completely dissolved, adding an anti-solvent until powder is precipitated, and filtering to obtain a saturated solution; Preferably, the supersaturation treatment is completed based on the fact that an equal amount of anti-solvent is added each time and an equal amount of powder is precipitated; Preferably, the anti-solvent comprises acetonitrile and / or toluene.

5. The preparation method according to claim 4, characterized in that: The mixing volume ratio of the saturated solution to the solvent in the dilution step is 1:(0.1-50), preferably 1:(0.3-4); Preferably, the concentration of the perovskite precursor solution obtained after the dilution operation is 0.01 mmol / mL-0.50 mmol / mL, preferably 0.05 mmol / mL-0.30 mmol / mL; Preferably, the pressurized pressure is 0.1 N / cm 2 -5N / cm 2 ; Preferably, the pressurization holding time is 1h-3h.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The preparation method of the PDMS template comprises: A silicon template with spaced cylindrical holes is prepared by photolithography; a PDMS precursor and a curing agent are mixed in a ratio of (10-9):1 and poured onto the hydrophobic treated silicon template; a PDMS template is obtained by vacuum treatment, heat curing and peeling.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The deposition is carried out in an anti-solvent atmosphere, the anti-solvent atmosphere being the same type as the anti-solvent used in the supersaturation treatment stage; Preferably, the deposition is carried out in a semi-closed device with an anti-solvent; Preferably, heating is performed during the deposition process; Preferably, the heating is divided into a first stage heating and a second stage heating; Preferably, the temperature of the first stage heating is 45°C-60°C; Preferably, the first stage heating time is 20min-30min; Preferably, the temperature of the second stage heating is 25°C-35°C; Preferably, the second stage heating time is 20h-30h.

8. A large-area perovskite micron sheet, characterized in that: The large-area perovskite microsheet Prepared by the preparation method according to any one of claims 1 to 7, the large-area perovskite micron sheet has a size of (100-350) μm×(100-350) μm.

9. A large-area perovskite micro-sheet microcavity, characterized in that: The large-area perovskite microsheet comprises the large-area perovskite microsheet according to claim 8.

10. A multi-dimensional laser, characterized in that: The multi-dimensional laser comprises the large-area perovskite microsheet microcavity as described in claim 9.

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