Preparation method of flexible perovskite thin film with bivalve shell structure

Abstract

The application discloses a preparation method of a flexible perovskite thin film with an imitation abalone shell structure. The method is inspired by the abalone shell structure, and a flexible thin film of polymer cemented perovskite grains is prepared through a dynamic diffusion process of a polar solvent assisted polymer, and belongs to the technical field of nanomaterials. First, a two-dimensional polystyrene nanosphere photonic crystal is assembled through a gas-liquid assembly, polystyrene nanospheres are etched by using a polar solvent, the generated polymer participates in a crystallization process of perovskite, and a 'brick-mud' structure of polymer cemented perovskite is constructed. Meanwhile, a multistage photonic structure is constructed through a nanoimprint technology. The synergistic effect of the 'brick-mud' structure and the deformable multistage photonic structure improves the flexibility of the perovskite thin film, and the perovskite thin film has a potential application prospect in the fields of wearable devices and flexible perovskite optoelectronics.

Description

Technical Field

[0001] This invention relates to a method for preparing a flexible perovskite thin film with an abalone shell-like structure, belonging to the field of nanomaterials technology. Background Technology

[0002] Perovskite is a material with a uniform chemical structure of ABX3, where A is typically formamidinium (CH(NH2)). + FA + ), Methylamine (CH3NH3) + MA + ), Cesium (Cs) + Organic or inorganic cations such as lead (Pb) and others, where B is lead (Pb). 2+ ), Tin (Sn) 2+ ), chromium (Ge 2+ Metal cations such as iodine (I) and others, where C is iodine (I) - ), bromine (Br - ), chlorine (Cl) - Halide anions, such as [BX6], are present. Among them, a classic perovskite is MAPbI3. Perovskite crystals are composed of [BX6]. 4- An octahedral array interconnected at its vertices forms a three-dimensional framework. In the single-cell structure of perovskite, the smaller cation B is located at the body center, interacting with six adjacent ions; the larger cation A is located in the interstices of the octahedrons, forming coordination with the surrounding twelve ions; and the anion X is located at the face center. Perovskite, as an emerging photosensitive material, can convert light energy into electrical energy, making full use of solar energy resources. This is due to its high light absorption coefficient (greater than 10). 5 / cm), tunable band gap (ultraviolet to near-infrared band), high carrier mobility (up to tens of cm⁻¹) 2 With its long carrier diffusion length (up to μm) and simple solution handling methods, perovskite materials can achieve high photoelectric conversion efficiency at low cost. Therefore, perovskite materials have good application value in optoelectronic devices such as solar cells, light-emitting diodes, photodetectors, and lasers.

[0003] Over the past decade, perovskite optoelectronic devices have achieved rapid development. Among them, perovskite solar cells have a power conversion efficiency (PCE) as high as 25.7%, perovskite light-emitting diodes (LEDs) have an external quantum efficiency (EQE) of 28.1%, and perovskite photodetectors have achieved high detectivity (D). Up to 10 15In addition, perovskite lasers have achieved continuous-wave lasing at room temperature. Although the optoelectronic performance of perovskite optoelectronic devices has reached or even surpassed that of other commercially available semiconductor materials, many scientific problems remain to be solved in promoting their commercialization. Due to their inherent brittleness (high elastic modulus), perovskite materials are prone to crack formation and propagation during bending or tensile deformation, especially for polycrystalline perovskite films. This damage is more pronounced because grain boundaries are stress concentration sites, thus limiting their application in flexible and wearable optoelectronic devices. In nature, the "brick-and-mortar" structure of abalone shell nacre consists of thin layers of organic protein bonding brittle layered calcium carbonate. This small amount of "mortar" cementing the brittle "brick" can exhibit high fracture toughness. This structure-property relationship provides inspiration for solving the above scientific problems by preparing perovskite-polymer composites to improve the flexibility of perovskite films. Adding polymers or polymer monomers to the antisolvent or precursor solution is a primary method for preparing perovskite-polymer composites. While this method can improve the flexibility of perovskite films, the polymer in the resulting perovskite-polymer composite is mostly distributed on the film surface and cannot penetrate along the grain boundaries. Furthermore, excessive blending of the polymer with the precursor can affect the crystallinity of the film. Another method to improve film flexibility is to spin-coat polymers onto the upper and lower surfaces of the perovskite film to create a polymer-perovskite-polymer sandwich structure. Although this sandwich structure distributes the brittle perovskite film within a flexible polymer layer, significantly improving film flexibility, the thickness of the polymer distributed on the upper and lower surfaces is difficult to precisely control, thus affecting the optoelectronic performance of the device. Additionally, the thin polymer layer is not distributed at the grain boundaries. In summary, while these perovskite-polymer preparation methods can improve the flexibility of perovskite films, the polymer does not penetrate along the grain boundaries. Moreover, the polymer content during the preparation process has a crucial impact on the crystallinity of the film and the optoelectronic performance of the device. Therefore, developing a universal method for self-encapsulating perovskite thin films by taking advantage of the liquid-phase crystallization of perovskites remains a challenge. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the above-mentioned methods and provide a method for preparing a flexible perovskite thin film with an abalone shell-like structure. This method is a universal approach inspired by abalone shells for self-encapsulating perovskite thin films. Inspired by natural abalone shells, a polar solvent is used to assist polymer diffusion, allowing the polymer to participate in the perovskite crystallization process, constructing a polymer-cemented perovskite "brick-and-mortar" structure. During this process, a deformable multi-level photonic structure is constructed using nanoimprinting technology.

[0005] The present invention adopts the following technical solution: A method for preparing a flexible perovskite thin film with an abalone shell-like structure includes the following steps: (1) Two-dimensional polystyrene nanosphere photonic crystal array and two-dimensional silica microsphere photonic crystal array were prepared respectively; (2) Preparation of polymer-cemented perovskite “brick-and-mortar” structures and deformable multi-level photonic structures: A. The two-dimensional polystyrene nanosphere photonic crystal array obtained in step (1) is subjected to solvent washing, air gun cleaning and plasma surface hydrophilic treatment; B. Dispersing an organic halide and lead halide in a mixed solvent to obtain a perovskite precursor solution; depositing the perovskite precursor solution onto the two-dimensional polystyrene nanosphere photonic crystal array obtained in step A at a rotation speed of 3000-5000 r / s and a time of 20-30 s; in the last 20-5 s (i.e., the remaining spin-coating time of 20-5 s), depositing an antisolvent onto the perovskite precursor solution at a dynamic rotation speed to obtain an intermediate state of the perovskite film. Preferably, the mixed solvent includes (i) dimethyl sulfoxide and (ii) γ-butyrolactone and / or N,N-dimethylformamide. Preferably, the lead halide is lead bromide (PbBr2) and / or lead iodide (PbI2).

[0006] C. The intermediate state of the perovskite film obtained in step B is imprinted using the two-dimensional silica microsphere photonic crystal array obtained in step (1). After imprinting, the film is placed on a hot stage at a temperature of 100-150 ℃ for annealing for 10-30 min to obtain a perovskite film that simultaneously possesses a deformable multi-level photonic structure and a polymer-bonded perovskite "brick-and-mortar" structure.

[0007] Further, in step (1), the dispersion of polystyrene nanospheres is assembled into a two-dimensional photonic crystal array by a gas-liquid assembly method. This two-dimensional photonic crystal array is placed in an environment with a temperature of 60-100 ℃ for 0.5-2 h, and the two-dimensional photonic crystal array is successfully transferred to a flexible substrate.

[0008] Further, in step (1), silica microspheres are assembled into a two-dimensional photonic crystal array by physical friction for imprinting template.

[0009] Furthermore, in step (2) B, the rotational speed is 3000-5000 r / s, and the time is 20-30 s.

[0010] Furthermore, in step (2) B, the spin coating time is 20-5 s remaining.

[0011] Furthermore, in step (2) C, the hot plate temperature is 100-150℃. The annealing time is 10-30 min.

[0012] Further, in step (2) A, the solvent is isopropanol, the isopropanol rinsing time is 2-5 s, and the residual solvent is immediately rinsed off with an air gun. The power of the plasma hydrophilic treatment is 50-300 W, and the time is 100-200 s.

[0013] Further, in step (2) B, the organic halide is selected from one, two, three or four of MAI, FAI, MABr and MACl.

[0014] Furthermore, the molar ratio of the organohalide to lead iodide is 0.8-1. For example, the molar ratio of the organohalide to lead halide is 0.8, 0.9, or 1.

[0015] Furthermore, the perovskite precursor solution described in step (2) B is a saturated solution.

[0016] Further, in step (2) B, when the solvent is γ-butyrolactone and dimethyl sulfoxide, the volume ratio of γ-butyrolactone to dimethyl sulfoxide is 7:3.

[0017] Further, in step (2) B, the antisolvent is toluene, chlorobenzene, or a polar solvent that dissolves polystyrene.

[0018] Further, step (2) involves the preparation of a self-encapsulated perovskite thin film.

[0019] A. The two-dimensional polystyrene photonic crystal array obtained in step (1) is rinsed with isopropanol, cleaned with an air gun, and subjected to plasma surface hydrophilic treatment.

[0020] Further, in step (2), B. MAI and PbI2 in a molar ratio of 1:1 are dispersed in a mixed solvent of γ-butyrolactone and dimethyl sulfoxide to obtain a saturated solution. Under the conditions of a rotation speed of 3000-5000 r / s and a time of 20-30 s, this saturated solution is deposited on the two-dimensional polystyrene photonic crystal array obtained in step A. When there are 20-5 s remaining in the spin-coating time, the antisolvent is deposited at a dynamic rotation speed to obtain an intermediate state of perovskite film.

[0021] Further, in step (2) C, the intermediate state of the perovskite thin film obtained in step B is imprinted using the two-dimensional silicon dioxide photonic crystal array obtained in step (1). After imprinting, the film is placed on a hot stage at 100 °C for annealing for 10-30 min.

[0022] The polystyrene nanospheres used in step (1) of this invention have a diameter of 200-900 nm. The silica microspheres used have a diameter of 1-10 μm. Both can be easily assembled on any substrate for large areas.

[0023] In step (2) of this invention, the isopropanol rinsing time in step (2)A is 2-5 s, and the residual solvent is immediately rinsed off with an air gun. The plasma hydrophilic treatment power is 50-300 W, and the time is 100-200 s, in order to increase the hydrophilicity of the array surface.

[0024] The perovskite precursor solution mentioned in step (2) B of this invention is a saturated solution with a concentration of 1.3-1.4 M; the volume ratio of the solvent γ-butyrolactone to dimethyl sulfoxide is 7:3; the antisolvent used is toluene, chlorobenzene and a polar solution that has a dissolving effect on polystyrene, and the amount of antisolvent deposited is 60-500 mL.

[0025] In step (2) of this invention, the imprinting time in C is 1-3 min; the tool used for imprinting is a flat plate clamp; during the imprinting process, a flexible substrate is placed at both ends of the flat plate clamp to prevent excessive pressure from damaging the sample.

[0026] The thickness of the perovskite film obtained after annealing in step (2) C of this invention is 500-800 nm.

[0027] In summary, compared to existing technologies, the advantages of this invention are as follows: Inspired by the "brick-and-mortar" structure of abalone shells, this invention utilizes the advantages of perovskite liquid-phase crystallization. Through etching with a polar solvent, polymers distributed at the bottom diffuse into the perovskite precursor solution to participate in the perovskite crystallization process, improving the crystallization quality of the thin film while forming a polymer-cemented perovskite "brick-and-mortar" structure. During this process, a variable multi-level photonic structure of a porous photonic crystal integrated hemispherical grating array is constructed using nanoimprinting technology. The synergistic effect of the deformable multi-level photonic structure and the "brick-and-mortar" structure greatly improves the flexibility of the perovskite thin film. The fabrication method of this invention is simple to operate, highly reproducible, has low production costs, and a short production cycle, and is expected to achieve commercial large-area fabrication. Attached Figure Description

[0028] Figure 1 Scanning electron microscope image of the two-dimensional polystyrene photonic crystal array prepared in Example 1.

[0029] Figure 2 A scanning electron microscope image of the two-dimensional silicon dioxide photonic crystal array prepared in Example 1.

[0030] Figure 3 The image shows a scanning electron microscope image of the perovskite thin film with a multi-level photonic structure prepared in Example 1.

[0031] Figure 4 High-resolution transmission electron microscope image of the self-encapsulated perovskite thin film prepared in Example 1.

[0032] Figure 5 The spectrum of ion intensity as a function of depth in the self-encapsulated perovskite thin film prepared in Example 1 is shown.

[0033] Figure 6 Finite element simulation of the perovskite thin film with deformable multi-level photonic structure and "brick-and-mortar" structure synergistic toughening prepared in Example 1. Detailed Implementation

[0034] The technical solution of the present invention will be further explained below with reference to specific embodiments. It is worth noting that the two-dimensional photonic crystal arrays involved in the following embodiments are all the two-dimensional photonic crystal arrays prepared in Example 1.

[0035] In the following embodiments of the present invention, the equipment used for plasma surface hydrophilic treatment is a low-temperature plasma treatment instrument - Suzhou Aopus Plasma Technology Co., Ltd. YS-DT02S.

[0036] Example 1

[0037] (1) Fabrication of two-dimensional photonic crystal arrays A 600 nm diameter polystyrene nanosphere dispersion (manufacturer: Shanghai Huizhi Biotechnology; brand: DS600; mass concentration: 5%) was diluted with a mixture of deionized water and ethanol in a volume ratio of 1:2:1. A flexible substrate was placed in a glass dish containing deionized water. The diluted nanosphere dispersion was then assembled into a two-dimensional photonic crystal array on the surface of the deionized water using a pipette. The glass dish containing the assembled two-dimensional photonic crystal array was incubated in an 80 °C oven for 30 min and then transferred to the flexible substrate. 2 μm diameter silica microsphere powder was placed on the substrate (2 × 2 cm). 2 On top of it, by covering it with another base (2×2cm) 2 Physical friction causes microspheres to assemble into a two-dimensional photonic crystal array.

[0038] (2) Preparation of self-encapsulated perovskite thin films The polystyrene photonic crystal array from (1) was cleaned with isopropanol solution for 2 s, rinsed with an air gun (nitrogen), and subjected to plasma surface hydrophilic treatment (100 W, 300 s). A saturated solution with a total volume of 1 mL was obtained by dispersing MAI and PbI2 in a 1:1 molar ratio in a mixed solvent of γ-butyrolactone and dimethyl sulfoxide in a 7:3 volume ratio, where the molar concentrations of MAI and PbI2 were 1.35 M and 1.35 M, respectively. This saturated solution served as the perovskite precursor solution. The saturated solution was deposited onto the polystyrene two-dimensional photonic crystal array treated in the above steps at a rotation speed of 3500 r / s for 30 s. At the last 7 s (i.e., 7 s remaining in the spin-coating time), 80 mL of toluene antisolvent was deposited onto the perovskite precursor solution using a pipette at a dynamic rotation speed to obtain an intermediate state of the perovskite film. The silica photonic crystal array from step (1) was applied over the intermediate state of the perovskite thin film obtained above, and imprinted onto it using a flat plate clamp for 1 min. After imprinting, it was immediately placed on a hot stage at 100 °C for annealing for 15 min. All the above steps were performed in air with a relative humidity of 30% and a temperature of 25 °C. After annealing, a self-encapsulated thin film with a porous two-dimensional photonic crystal and a hemispherical grating integrated multi-level photonic structure and polystyrene-coated perovskite grains was obtained, with a film thickness of ~700 nm.

[0039] Figure 1 The image shows a scanning electron microscope image of the two-dimensional polystyrene photonic crystal array obtained in Example 1. The image clearly shows that the photonic crystal array has a compact hexagonal stacked structure. Figure 2 The image shown is a scanning electron microscope image of the two-dimensional silica photonic crystal array obtained in Example 1. Similar to the polystyrene photonic crystal array, it also exhibits a compact hexagonal stacked structure. Figure 3 The image shows a scanning electron microscope image of the perovskite thin film with a multi-level photonic structure obtained in Example 1. The image shows the successful construction of the multi-level photonic structure with a porous photonic crystal integrated hemispherical grating. The diameter of the imprinted hemispherical grating is 1 μm and the period is 2 μm. The diameter of the etched porous photonic crystal is 450 nm. Figure 4 The high-resolution transmission electron microscope image of the self-encapsulated perovskite film prepared in Example 1 shows that the perovskite grains are coated with a thin layer of amorphous polystyrene polymer, proving the formation of the polymer-coated perovskite film. Figure 5 The graph shows the ion intensity variation with depth in the self-encapsulated perovskite film prepared in Example 1. The similar trend of the polymer and perovskite signals with depth indicates that polymers are present on the upper surface, bulk grain boundaries, and potential lower surface of the perovskite film, further demonstrating the successful preparation of polymer-coated perovskite films. Figure 6Finite element simulations of the perovskite thin film toughened by the deformable multilevel photonic structure and the "brick-and-mortar" structure prepared in Example 1 show that the polymer at the grain boundaries can improve the ductility of the grain boundaries, and the deformable multilevel photonic structure, as a buffer layer, can release the stress and strain generated by bending. The synergistic effect of the two reduces the stress volume distributed on the film, inhibits the generation and propagation of cracks, and improves the flexibility of the perovskite thin film.

[0040] Example 2

[0041] The polystyrene photonic crystal array from step (1) of Example 1 was cleaned with isopropanol solution for 2 s, rinsed with a gas gun (nitrogen), and subjected to plasma surface hydrophilic treatment (200 W, 300 s). A saturated solution with a total volume of 1 mL was obtained by dispersing MAI and PbI2 in a 1:1 molar ratio in a mixed solvent of γ-butyrolactone and dimethyl sulfoxide in a 7:3 volume ratio, where the molar concentrations of MAI and PbI2 were 1.3 M. This saturated solution served as a perovskite precursor solution. The saturated solution was deposited onto the polystyrene two-dimensional photonic crystal array treated in the above steps at a rotation speed of 4000 r / s for 30 s. In the last 10 s, 100 mL of toluene antisolvent was deposited onto the perovskite precursor solution using a pipette at a dynamic rotation speed to obtain an intermediate state of the perovskite thin film. The silica photonic crystal array from step (1) of Example 1 was applied over the intermediate state of the perovskite thin film obtained above, and imprinted onto it using a flat clamp for 1 min. After imprinting, it was immediately placed on a hot stage at 100 °C for annealing for 10 min. All the above steps were performed in air with a relative humidity of 35% and a temperature of 25 °C. After annealing, a self-encapsulated thin film with a porous two-dimensional photonic crystal and a hemispherical grating integrated multi-level photonic structure and polystyrene-coated perovskite grains was obtained, with a film thickness of ~650 nm.

[0042] Example 3

[0043] The polystyrene photonic crystal array from step (1) of Example 1 was cleaned with isopropanol solution for 3 s, rinsed with a gas gun (nitrogen), and subjected to plasma surface hydrophilic treatment (100 W, 300 s). MAI and PbI2 in a molar ratio of 1:1 were dispersed in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1 to obtain a saturated solution with a total volume of 1 mL. In this saturated solution, the molar concentrations of MAI and PbI2 were 1.35 M and 1.35 M, respectively. This saturated solution served as a perovskite precursor solution. At a rotation speed of 3500 r / s and a time of 30 s, the saturated solution was deposited onto the polystyrene two-dimensional photonic crystal array treated in the above step. Ten s after the start, 200 mL of chlorobenzene antisolvent was deposited onto the perovskite precursor solution using a pipette at a dynamic rotation speed to obtain an intermediate state of the perovskite thin film. The silica photonic crystal array from step (1) of Example 1 was applied over the intermediate state of the perovskite thin film obtained above, and imprinted using a flat clamp for 1 minute. After imprinting, it was immediately placed on a hot stage at 100 °C for annealing for 15 minutes. All the above steps were performed in air with a relative humidity of 30% and a temperature of 25 °C. After annealing, a self-encapsulated thin film with a porous two-dimensional photonic crystal and a hemispherical grating integrated multi-level photonic structure and polystyrene-coated perovskite grains was obtained, with a film thickness of ~720 nm.

[0044] Example 4

[0045] The polystyrene photonic crystal array from step (1) of Example 1 was cleaned with isopropanol solution for 2 s, rinsed with a gas gun (nitrogen), and subjected to plasma surface hydrophilic treatment (200 W, 300 s). MAI and PbI2 in a molar ratio of 1:1 were dispersed in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1 to obtain a saturated solution with a total volume of 1 mL. In this saturated solution, the molar concentrations of MAI and PbI2 were 1.35 M and 1.35 M, respectively. This saturated solution served as a perovskite precursor solution. At a rotation speed of 4000 r / s and a time of 30 s, the saturated solution was deposited onto the polystyrene two-dimensional photonic crystal array treated in the above step. Ten s after the start, 150 mL of chlorobenzene antisolvent was deposited onto the perovskite precursor solution using a pipette at a dynamic rotation speed to obtain an intermediate state of the perovskite thin film. The silicon dioxide photonic crystal array from step (1) of Example 1 was applied over the intermediate state of the perovskite thin film obtained above, and imprinted on it using a flat plate clamp for 2 min. After imprinting, it was immediately placed on a hot stage at 100 °C for annealing for 20 min. All the above steps were performed in air with a relative humidity of 35% and a temperature of 25 °C. After annealing, a self-encapsulated thin film with a porous two-dimensional photonic crystal and a hemispherical grating integrated multi-level photonic structure and polystyrene-coated perovskite grains was obtained, with a film thickness of ~680 nm.

[0046] Example 5

[0047] The polystyrene photonic crystal array from step (1) of Example 1 was cleaned with isopropanol solution for 2 s, rinsed with a gas gun (nitrogen), and subjected to plasma surface hydrophilic treatment (100 W, 200 s). MAI and PbI2 in a molar ratio of 1:1 were dispersed in a mixed solvent of γ-butyrolactone and dimethyl sulfoxide in a volume ratio of 7:3 to obtain a saturated solution with a total volume of 1 mL. In this saturated solution, the molar concentrations of MAI and PbI2 were 1.3 M. This saturated solution served as a perovskite precursor solution. At a rotation speed of 3500 r / s and a time of 30 s, the saturated solution was deposited onto the polystyrene two-dimensional photonic crystal array treated in the above steps. In the last 10 s, 120 mL of chlorobenzene antisolvent was deposited onto the perovskite precursor solution using a pipette at a dynamic rotation speed to obtain an intermediate state of the perovskite thin film. The silica photonic crystal array from step (1) of Example 1 was applied over the intermediate state of the perovskite thin film obtained above, and imprinted using a flat clamp for 2 min. After imprinting, it was immediately placed on a hot stage at 100 °C for annealing for 30 min. All the above steps were performed in air with a relative humidity of 30% and a temperature of 25 °C. After annealing, a self-encapsulated thin film (thickness ~700 nm) with a multi-level photonic structure integrating a porous two-dimensional photonic crystal and a hemispherical grating and polystyrene-coated perovskite grains was obtained.

[0048] Example 6

[0049] The polystyrene photonic crystal array from step (1) of Example 1 was cleaned with isopropanol solution for 2 s, rinsed with an air gun (nitrogen), and subjected to plasma surface hydrophilic treatment (200 W, 300 s). PbI₂, FAI, MABr, PbBr₂, and MACl were dispersed in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide at a volume ratio of 4:1 to obtain a saturated solution with a total volume of 1 mL. The molar concentrations of the solutes in the saturated solution were: PbI₂ 1.53 M, FAI 1.4 M, MABr 0.11 M, PbBr₂ 0.11 M, and MACl 0.5 M. This saturated solution served as a perovskite precursor solution. Under two rotational speeds: 1000 r / s, 10 s, and 5000 r / s for 30 s, a saturated solution was deposited onto the polystyrene two-dimensional photonic crystal array treated in the above steps. In the last 10 s, 150 mL of chlorobenzene antisolvent was deposited onto the perovskite precursor solution using a pipette at a dynamic rotational speed to obtain an intermediate state of the perovskite film. The silica photonic crystal array from step (1) of Example 1 was then placed over the obtained intermediate state of the perovskite film and imprinted using a flat plate clamp for 1 min. After imprinting, the film was immediately placed on a hot stage at 150 ℃ for annealing for 15 min. All the above steps were performed in air with a relative humidity of 35% and a temperature of 25 ℃. After annealing, a self-encapsulated film with a porous two-dimensional photonic crystal and a hemispherical grating integrated multi-level photonic structure and polystyrene-coated perovskite grains was obtained, with a film thickness of ~800 nm.

[0050] Example 7

[0051] The polystyrene photonic crystal array from step (1) of Example 1 was cleaned with isopropanol solution for 2 s, rinsed with an air gun (nitrogen), and subjected to plasma surface hydrophilic treatment (150 W, 300 s). PbI₂, FAI, MABr, PbBr₂, and MACl were dispersed in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide at a volume ratio of 4:1 to obtain a saturated solution with a total volume of 1 mL. The molar concentrations of the solutes in the saturated solution were: PbI₂ 1.53 M, FAI 1.4 M, MABr 0.08 M, PbBr₂ 0.08 M, and MACl 0.5 M. This saturated solution served as a perovskite precursor solution. Under two rotational speeds: 1000 r / s, 10 s, and 4000 r / s for 30 s, a saturated solution was deposited onto the polystyrene two-dimensional photonic crystal array treated in the above steps. In the last 15 s, 200 mL of chlorobenzene antisolvent was deposited onto the perovskite precursor solution using a pipette at a dynamic rotational speed to obtain an intermediate state of the perovskite film. The silica photonic crystal array from step (1) of Example 1 was then covered onto the obtained intermediate state of the perovskite film, and imprinted using a flat plate clamp for 1 min. After imprinting, it was immediately placed on a hot stage at 100 ℃ for 15 min, and then annealed again on a hot stage at 150 ℃ for 15 min. All the above steps were performed in air with a relative humidity of 30% and a temperature of 25 ℃. After annealing, a self-encapsulated film (film thickness of ~800 nm) with a multi-level photonic structure integrating a porous two-dimensional photonic crystal and a hemispherical grating and polystyrene-coated perovskite grains was obtained.

[0052] Example 8

[0053] The polystyrene photonic crystal array from step (1) of Example 1 was cleaned with isopropanol solution for 3 s, rinsed with a gas gun (nitrogen), and subjected to plasma surface hydrophilic treatment (100 W, 300 s). A saturated solution with a total volume of 1 mL was obtained by dispersing 1.53 M PbI₂, 1.4 MFA, 0.08 M MABr, 0.08 M PbBr₂, and 0.5 M MACl in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide at a volume ratio of 9:1. This saturated solution served as the perovskite precursor solution. The saturated solution was deposited onto the polystyrene two-dimensional photonic crystal array treated in the above steps under two rotational speeds: 1000 r / s, 10 s, and 5000 r / s, for a time of 30 s. In the last 5 s, 150 mL of toluene antisolvent was deposited onto the perovskite precursor solution using a pipette at a dynamic rotational speed to obtain an intermediate state of the perovskite film. The silica photonic crystal array from step (1) of Example 1 was applied to the intermediate state of the perovskite thin film obtained above, and imprinted onto it using a flat plate clamp for 1 min. After imprinting, it was immediately placed on a hot stage at 150 °C for annealing for 15 min. All the above steps were performed in air with a relative humidity of 35% and a temperature of 25 °C. After annealing, a self-encapsulated thin film (thickness ~780 nm) with a multi-level photonic structure integrating a porous two-dimensional photonic crystal and a hemispherical grating and polystyrene-coated perovskite grains was obtained.

[0054] The embodiments described above merely illustrate several aspects of the present invention and further elaborate on the technical solution. They are not intended to limit the scope of the invention in any way. It should be noted that any non-essential improvements and adjustments made by those skilled in the art without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A method for preparing a flexible perovskite thin film with an abalone shell-like structure, characterized in that, The method includes the following steps: (1) Two-dimensional polystyrene nanosphere photonic crystal array and two-dimensional silica microsphere photonic crystal array were prepared respectively; (2) Preparation of polymer-cemented perovskite "brick-and-mortar" structures and deformable multi-level photonic structures: A. The two-dimensional polystyrene nanosphere photonic crystal array obtained in step (1) is subjected to solvent washing, air gun cleaning and plasma surface hydrophilic treatment; B. Disperse an organic halide and lead halide in a mixed solvent to obtain a perovskite precursor solution; deposit the perovskite precursor solution onto the two-dimensional polystyrene nanosphere photonic crystal array obtained in step A at a rotation speed of 3000-5000 r / s and a time of 20-30 s; in the last 20-5 s, deposit an antisolvent onto the perovskite precursor solution at a dynamic rotation speed to obtain an intermediate state of the perovskite film; the mixed solvent includes (i) dimethyl sulfoxide and (ii) γ-butyrolactone and / or N,N-dimethylformamide; the lead halide is lead bromide and / or lead iodide; C. Imprint the intermediate state of the perovskite film obtained in step B using the two-dimensional silica microsphere photonic crystal array obtained in step (1). After imprinting, place it on a hot stage at a temperature of 100-150 ℃ for annealing for 10-30 min to obtain a perovskite film that simultaneously has a deformable multi-level photonic structure and a polymer-bonded perovskite "brick-mud" structure. In step (1), the preparation of the two-dimensional polystyrene nanosphere photonic crystal array includes: assembling the polystyrene nanosphere dispersion into a two-dimensional photonic crystal array, placing the two-dimensional photonic crystal array in an environment with a temperature of 60-100 ℃ for 0.5-2 h, and transferring the two-dimensional photonic crystal array onto a flexible substrate; In step (1), the preparation of the two-dimensional silica microsphere photonic crystal array includes: assembling silica microspheres into a two-dimensional photonic crystal array for imprinting template by physical means; the assembly method of silica microspheres is friction assembly, and the diameter of the silica microspheres used is 1-10 μm; In step (1), the polystyrene nanosphere dispersion is assembled at the gas-liquid interface, and the diameter of the polystyrene nanospheres used is 200-900 nm. The method utilizes the advantages of liquid-phase crystallization of perovskite. Through etching with a polar solvent, the polymer distributed at the bottom diffuses into the perovskite precursor solution to participate in the crystallization process of perovskite. This improves the crystallization quality of the thin film and forms a "brick-and-mortar" structure of polymer-cemented perovskite. In this process, a deformable multi-level photonic structure of a porous photonic crystal integrated hemispherical grating array is constructed using nanoimprint technology.

2. The method for preparing a flexible perovskite thin film with an abalone shell-like structure according to claim 1, characterized in that: In step (2) A, the solvent is isopropanol, the isopropanol rinsing time is 2-5 s, and the residual solvent is immediately rinsed off with an air gun; the power of the plasma hydrophilic treatment is 50-300 W, and the time is 100-200 s.

3. The method for preparing a flexible perovskite thin film with an abalone shell-like structure according to claim 1, characterized in that: In step (2) B, the organic halide is selected from one, two, three or four of methylammonium iodide, formamidinium iodide, methylammonium bromide and methylammonium chloride; the molar ratio of the organic halide to lead halide is 0.8-1.

4. The method for preparing a flexible perovskite thin film with an abalone shell structure according to claim 1, characterized in that: The perovskite precursor solution mentioned in step (2) B is a saturated solution.

5. The method for preparing a flexible perovskite thin film with an abalone shell structure according to claim 1, characterized in that: The antisolvent is toluene or chlorobenzene.

6. The method for preparing a flexible perovskite thin film with an abalone shell-like structure according to claim 1, characterized in that: The imprinting time in step (2) C is 1-3 min; the imprinting tool is a flat clamp; the thickness of the perovskite film is 500-800 nm.

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