Flexible perovskite thin film, preparation method thereof and perovskite device comprising flexible perovskite thin film

Abstract

The invention discloses a method for preparing a flexible perovskite thin film through a spraying method, and the method comprises the following steps: S1, carrying out the ultrasonic cleaning of a flexible conductive substrate in a cleaning solvent, and placing the cleaned flexible conductive substrate in a drying oven for drying; s2, the spray gun is placed in a drying oven to be dried after being cleaned; s3, after the flexible conductive substrate is subjected to ultraviolet ozone treatment, preparing a charge transport layer on the flexible conductive substrate; s4, after the charge transfer layer is subjected to ultraviolet ozone treatment, the flexible conductive substrate and the charge transfer layer are placed on a heating table together to be heated; s5, filling the perovskite precursor solution into a spray gun; s6, spraying by a spray gun to form a flexible perovskite coating; s7, the spray gun continues spraying to form a flexible perovskite coating; s8, repeating the step S7 to form a flexible perovskite thin film; and S9, nitrogen flow purging and nitrogen spray gun purging are adopted, and finally annealing treatment is performed on the flexible perovskite thin film. The method is controllable in process, high in film forming quality, high in efficiency, high in uniformity and good in mechanical flexibility.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic devices, and more specifically, relates to flexible perovskite thin films, their preparation methods, and perovskite devices containing them. Background Technology

[0002] Perovskite materials are a class of semiconductor compounds with an ABX3 crystal structure. In recent years, due to their excellent photoelectric properties (such as high light absorption coefficient, long carrier diffusion length, tunable bandgap, and low defect state density), they have shown great application potential in photovoltaics, light emission, and detection. In particular, perovskite solar cells have achieved a photoelectric conversion efficiency exceeding 26%, making them a highly promising next-generation photovoltaic technology. With the development of wearable electronics, flexible displays, and portable energy systems, integrating perovskite materials onto flexible substrates (such as PET and PI) to fabricate high-performance flexible perovskite optoelectronic devices has become an important research direction.

[0003] Currently, the preparation of flexible perovskite thin films mainly relies on processes such as spin coating, blade coating, slot coating, or vacuum evaporation. While spin coating can produce high-quality films, it suffers from low material utilization, difficulty in large-area fabrication, and stringent requirements for the flatness and rotational stability of the flexible substrate. Blasting and slot coating, though suitable for roll-to-roll production, have stringent requirements for ink viscosity, substrate tension, and environmental control. Vacuum evaporation, on the other hand, is costly and complex, hindering low-cost, large-scale applications. In recent years, spray coating has been increasingly explored for perovskite thin film preparation due to its advantages of simple equipment, flexible process, applicability to non-planar and large-area flexible substrates, and high material utilization. This method involves atomizing a perovskite precursor solution and spraying it onto a heated substrate, where solvent evaporation and crystallization form the thin film. Theoretically, it possesses good scalability and industrialization potential.

[0004] However, perovskite thin films prepared by existing spraying methods still face many technical bottlenecks: on the one hand, atomized droplets on flexible substrates are prone to uneven film formation, numerous pinholes, and small grain size due to low surface energy and poor thermal conductivity; on the other hand, the limited temperature resistance of flexible substrates (typically <150℃) restricts the use of high-temperature annealing processes, making it difficult to improve the crystal quality of perovskite, thus affecting device efficiency and stability. In addition, the rapid evaporation of solvents during spraying can easily induce the coffee ring effect and component segregation, further exacerbating the inhomogeneity of the film. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the prior art, the present invention provides a flexible perovskite thin film, a method for preparing the same, and a perovskite device containing the same, which has controllable process, high film quality, and takes into account high efficiency, high uniformity and good mechanical flexibility.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for preparing flexible perovskite thin films by spray coating is provided, comprising the following steps: S1. After ultrasonically cleaning the flexible conductive substrate in a cleaning solvent, place it in an oven to dry. S2. After cleaning the spray gun, place it in an oven to dry. S3. After the flexible conductive substrate is treated with ultraviolet ozone, a charge transport layer is prepared on the flexible conductive substrate. The charge transport layer is an electron transport layer or a hole transport layer. S4. Place the flexible conductive substrate and the charge transport layer together in an ultraviolet ozone environment. After the charge transport layer is treated with ultraviolet ozone, place the flexible conductive substrate and the charge transport layer together on a hot stage. The hot stage heats the charge transport layer to a set temperature. S5. Load the perovskite precursor solution into the spray gun, wherein the perovskite precursor solution is a precursor solution for preparing three-dimensional perovskite or a precursor solution for preparing quasi-two-dimensional perovskite. S6. Control the spray pressure of the spray gun. The spray gun sprays the perovskite precursor solution evenly onto the charge transport layer. Then the spray gun stops spraying. The perovskite precursor solution solidifies to form a flexible perovskite coating. The hot table heats the flexible perovskite coating to anneal it. S7. Control the spray pressure of the spray gun. The spray gun evenly sprays the perovskite precursor solution onto the flexible perovskite coating. The perovskite precursor solution solidifies to form a flexible perovskite coating. S8. Repeat step S7 until the flexible perovskite film composed of all the flexible perovskite coatings reaches the set thickness. S9. First, purge the gas above the hot stage with a nitrogen gas flow, then purge the flexible perovskite film with a nitrogen spray gun, and finally anneal the flexible perovskite film.

[0007] Preferably, in step S4, the hot stage heats the charge transport layer to a set temperature of 60°C-110°C; In step S5, when the perovskite precursor solution is used to prepare a three-dimensional perovskite precursor solution, the molar concentration of the precursor solution used to prepare the three-dimensional perovskite is 0.8 mol / L–2 mol / L. In step S6, the spray pressure of the spray gun is 0.1MPa-0.3MPa.

[0008] Regarding the molar concentration of the precursor solution used for preparing three-dimensional perovskites, it is defined as 0.8 mol / L–2 mol / L. This concentration range provides excellent compatibility with the spraying process and the characteristics of the flexible substrate. If the concentration is too low, the perovskite precursor content in the solution is insufficient, resulting in a thin and poorly dense coating after a single spraying. This coating is prone to defects such as pinholes and cracks, and multiple sprayings are required to achieve the set thickness. This not only reduces the preparation efficiency but may also affect the overall integrity of the film due to poor interlayer bonding. If the concentration is too high, the solution viscosity will increase, resulting in poor atomization and droplet aggregation. This makes it difficult to spread evenly on the surface of the charge transport layer after spraying, leading to component segregation and uneven film formation. The concentration range of 0.8 mol / L–2 mol / L ensures that the solution has suitable viscosity and fluidity, ensuring that the atomized droplets are uniform in size after spraying, and that each layer of perovskite coating has sufficient precursor content, so that a dense and continuous perovskite coating is formed after curing. At the same time, it takes into account the tightness of interlayer bonding and the overall structural integrity of the film.

[0009] The heating stage's temperature limit of 60℃-110℃ achieves a balance between perovskite crystallization and the resilience of the flexible substrate. This temperature range provides sufficient energy for solvent evaporation and crystal growth in the three-dimensional perovskite precursor solution, promoting the ordered arrangement of precursor molecules, reducing lattice defects, improving crystal quality and grain size, and thus enhancing the film's charge transport capability and photoelectric conversion efficiency. Simultaneously, the 60℃-110℃ temperature is below the heat resistance limit of most flexible substrates, effectively preventing deformation, aging, or performance degradation caused by high temperatures, ensuring the structural stability and performance consistency of the substrate during preparation. Furthermore, this temperature range allows for precise control of the solvent evaporation rate, avoiding both the coffee ring effect and component segregation caused by excessively rapid evaporation, and problems such as coating sagging and insufficient curing caused by excessively slow evaporation. This ensures that each perovskite coating layer can complete crystallization and curing under stable temperature conditions, improving the film's uniformity and repeatability.

[0010] The spray gun's jet pressure (atomizing pressure) of 0.1MPa-0.3MPa is a core parameter ensuring coating uniformity. The jet pressure directly determines the atomization effect of the precursor solution, droplet velocity, and coverage area. If the pressure is too low, the atomized droplets will be too large and unevenly distributed, easily forming localized accumulations or coverage gaps on the substrate surface after spraying, leading to coating thickness fluctuations. If the pressure is too high, the droplet impact force will be too great, potentially damaging the existing coating structure or causing material waste and film defects due to droplet splashing. A pressure range of 0.1MPa-0.3MPa allows the spray gun to atomize the three-dimensional perovskite precursor solution into uniformly sized, densely distributed micro-droplets. These droplets, sprayed at an appropriate velocity onto the charge transport layer surface, can spread quickly and evenly, ensuring consistent coating thickness and complete coverage for each layer. Meanwhile, the atomized droplets under this pressure can work synergistically with the heating temperature of 60℃-110℃. After the droplets come into contact with the heated substrate, the solvent evaporates rapidly and uniformly, further promoting the synchronous growth of perovskite crystals, reducing crystal defects and interface impedance, and improving the photoelectric properties and structural stability of the thin film.

[0011] By limiting the concentration of the precursor solution, heating temperature, and jetting pressure used to prepare three-dimensional perovskites, a synergistic effect is achieved among the various process steps. This ensures the stability and controllability of the spraying process, optimizes the crystal quality, density, and uniformity of the perovskite film, and effectively improves the photoelectric conversion efficiency, mechanical stability, and long-term reliability of the film. This provides key process parameters for the preparation of high-performance flexible perovskite devices.

[0012] Preferably, the precursor solution used to prepare three-dimensional perovskite contains FA. + MA + Cs + Pb 2+ The solvent used to prepare the precursor solution of three-dimensional perovskite is a mixture of N,N-dimethylformamide and acetonitrile, and the volume ratio of N,N-dimethylformamide to acetonitrile is (4~9):1.

[0013] FA in precursor solution + MA + Cs + Pb 2+ The synergistic combination with halide ions constructs a multi-element doped three-dimensional perovskite crystal structure, significantly optimizing the material's photoelectric properties and structural stability. FA + The introduction of formamidinium ions can expand the lattice constant of perovskite crystals, increase the light absorption range, especially enhance the light response in the near-infrared region, thereby improving the light absorption efficiency of the thin film; MA + (Methylamine ions) help reduce the density of defect states in the crystal, improve carrier mobility, and promote efficient charge transport within the thin film; Cs+ Cesium ion doping can effectively suppress phase transitions in perovskite crystals, enhance the thermal and chemical stability of the material, and prevent performance degradation due to crystal structure changes during subsequent annealing and long-term use; Pb 2+ Using halide ions (such as I⁻, Br⁻, etc.) as the basic framework of perovskite crystals, their reasonable ratio ensures the integrity and regularity of the crystal structure, laying the structural foundation for the realization of excellent photoelectric properties. The synergistic effect of multiple ions enables the prepared three-dimensional perovskite thin film to have both high light absorption coefficient and excellent charge transport capability and structural stability, effectively making up for the performance shortcomings of perovskite materials composed of single ions.

[0014] In the solvent system design, N,N-dimethylformamide (DMF) and acetonitrile were mixed at a volume ratio of (4~9):1 as the solvent, achieving a precise balance between the solubility, viscosity, and evaporation rate of the precursor solution, providing an optimal solution environment for the spray coating film formation process. DMF, as a highly polar solvent, is effective against FA... + MA + Cs + Pb 2+ Plasma has extremely strong dissolving power, which can ensure that all components of the precursor are fully dissolved to form a uniform and stable solution, avoiding film defects caused by solute precipitation; Acetonitrile has the characteristics of low viscosity and high volatility. Its appropriate addition can effectively adjust the viscosity and surface tension of the mixed solvent, so that the solution has suitable fluidity and is suitable for the requirements of the spray gun atomization process—ensuring that the solution can be uniformly atomized into tiny droplets, while avoiding droplet agglomeration due to excessive viscosity or excessive droplet diffusion during the spraying process due to excessively low viscosity.

[0015] The volume ratio limit of (4~9):1 is a key parameter that has been precisely optimized: when the DMF ratio is too high, the evaporation rate of the mixed solvent is too slow, and the solvent cannot evaporate quickly on the substrate surface after spraying, which can easily cause coating sagging, component segregation, and may lead to uneven crystal growth, forming coarse grains and grain boundary defects; when the acetonitrile ratio is too high, the solvent evaporation rate is too fast, which can easily cause the coffee ring effect, resulting in ring-shaped protrusions and depressions on the film surface. At the same time, the rapid evaporation of the solvent may prevent the precursor from fully crystallizing, forming an amorphous or low-crystallinity film structure. The volume ratio range of (4~9):1 can make the evaporation rate of the mixed solvent perfectly coordinated with the spraying process and the heating temperature of the hot plate (60℃-110℃). After the droplets are sprayed onto the heated substrate surface, the solvent can evaporate quickly and uniformly, which provides sufficient time for the nucleation and orderly growth of perovskite crystals, and avoids various film defects caused by abnormal evaporation rates.

[0016] Furthermore, this solvent system exhibits excellent compatibility with the precursor ionic components, effectively suppressing ion segregation and ensuring uniform ion distribution during perovskite crystal growth, resulting in a homogeneous crystal structure and further enhancing the consistency of the film's photoelectric properties. Simultaneously, the mixed solvent of DMF and acetonitrile demonstrates good chemical stability, preventing chemical reactions with the precursor components during spraying and annealing, and avoiding corrosion or damage to the flexible substrate, thus ensuring the safety and reliability of the fabrication process.

[0017] In summary, by precisely defining the ionic composition and solvent system of the three-dimensional perovskite precursor solution, a deep fit between material properties and fabrication process was achieved. This not only ensured the stability of the precursor solution and the uniformity of atomization film formation, but also fundamentally improved the crystal quality, photoelectric conversion efficiency, structural stability, and performance consistency of flexible perovskite films, providing key material and process guarantees for the large-scale fabrication of high-performance flexible perovskite devices.

[0018] Preferably, in step S4, the hot stage heats the charge transport layer to a set temperature of 60°C-110°C; In step S5, when the perovskite precursor solution is used to prepare a quasi-two-dimensional perovskite precursor solution, the n value of the prepared quasi-two-dimensional perovskite is 11~31, where n is the number of inorganic layers. In step S6, the spray pressure of the spray gun is 0.1MPa-0.3MPa.

[0019] Limiting the n-value (number of inorganic layers) to 11-31 is a core design principle ensuring both photoelectric performance and mechanical flexibility in the thin film. The n-value of quasi-two-dimensional perovskites directly determines the ratio of inorganic semiconductor layers to organic layers in their crystal structure, thus affecting the material's photoelectric transmission characteristics and mechanical deformation capabilities. Setting the n-value within the range of 11-31 ensures a sufficient number of inorganic layers in the crystal structure, maintaining efficient charge transport channels and keeping carrier mobility at a high level, thus guaranteeing excellent photoelectric conversion performance. Simultaneously, the presence of organic layers provides good mechanical flexibility, allowing the film to adapt to bending and folding deformations on flexible substrates and preventing cracking or performance degradation under stress. This precisely optimized n-value range achieves a balance between the high photoelectric activity of the inorganic layers and the flexible support of the organic layers. This results in flexible perovskite thin films that possess both near-three-dimensional perovskite high charge transport efficiency and superior structural stability and mechanical tolerance compared to quasi-two-dimensional perovskites with lower n-values, meeting the core requirements of flexible applications such as wearable electronics.

[0020] The heating temperature range of 60℃-110℃ provides an optimal temperature environment for the crystallization process of the precursor solution used to prepare quasi-two-dimensional perovskites. The crystal growth of quasi-two-dimensional perovskites is more temperature-sensitive, and this temperature range provides sufficient energy for the orderly assembly of organic and inorganic components in the precursor solution, promoting the formation of a regular, dense layered crystal structure, reducing the defect density and grain boundary impedance within the crystal, thereby improving carrier separation and transport efficiency. Simultaneously, the temperature range of 60℃-110℃ is strictly controlled within the heat resistance threshold of the flexible substrate, effectively preventing substrate deformation, aging, or conductivity degradation caused by high temperatures, ensuring the stability of the substrate and film structure during the preparation process. Furthermore, this temperature range allows for precise control of the solvent evaporation rate, preventing component segregation and the coffee ring effect caused by excessively rapid evaporation, while avoiding problems such as coating sagging and poor interlayer bonding caused by excessively slow evaporation. This ensures that each perovskite coating layer can complete crystallization and solidification under stable temperature conditions, improving the thickness uniformity and performance repeatability of the film.

[0021] The spray gun's pressure limit of 0.1MPa-0.3MPa synergizes effectively with the characteristics of the precursor solution used to prepare quasi-two-dimensional perovskites. Because the precursor solution for quasi-two-dimensional perovskites contains organic components, its viscosity and surface tension characteristics differ from those of the precursor solution used to prepare three-dimensional perovskites. The pressure range of 0.1MPa-0.3MPa allows the spray gun to atomize the solution into uniformly sized, densely distributed microdroplets. These droplets are sprayed onto the charge transport layer surface with appropriate impact force and coverage, allowing for rapid and uniform spreading, avoiding droplet aggregation or localized coverage gaps. The atomized droplets at this pressure, combined with a heating temperature of 60℃-110℃, enable rapid solvent evaporation and crystal nucleation upon contact with the substrate, reducing the migration and loss of organic components and ensuring the integrity of the perovskite crystal structure. Meanwhile, appropriate jetting pressure can avoid mechanical damage to the formed coating, ensuring the structural integrity of each layer and the tightness of interlayer bonding during the layered spraying process, ultimately forming a flexible perovskite film with uniform thickness and high density.

[0022] Preferably, the precursor solution used to prepare quasi-two-dimensional perovskite contains FA. + MA + Cs + Pb 2+ The solvent used to prepare the precursor solution of the quasi-two-dimensional perovskite is a mixture of N,N-dimethylformamide and acetonitrile, and the volume ratio of N,N-dimethylformamide to acetonitrile is (4~9):1. The long-chain organic amine is n-butylamine ion or phenylethylamine ion.

[0023] The precursor solution used to prepare quasi-two-dimensional perovskite contains FA. + MA+ Cs + Pb 2+ Long-chain organic amine ions and halide ions were used to construct a multi-component, synergistic quasi-two-dimensional perovskite crystal structure. FA + The introduction of MA can expand the crystal lattice constant, broaden the light absorption range of the thin film, especially enhance the light response in the near-infrared region, and significantly improve the light absorption efficiency; + It can effectively reduce the density of defect states in the crystal, optimize the carrier migration path, promote efficient charge transport inside the thin film, and reduce carrier recombination losses; Cs + Doping with Pb can suppress the phase transition tendency of perovskite crystals, enhance the thermal and chemical stability of the material, and avoid performance degradation due to changes in crystal structure during subsequent annealing and long-term use; 2+ The rational ratio of halogen ions, forming the basic crystal framework, ensures the integrity and regularity of the crystal structure, laying the structural foundation for excellent photoelectric performance. The addition of long-chain organic amine ions is key to the good mechanical flexibility of the quasi-two-dimensional perovskite. These ions form a flexible support network within the crystal structure, enabling the film to adapt to the bending and folding deformations of flexible substrates, preventing cracking or performance degradation under stress, and perfectly suited for flexible applications such as wearable electronics. The synergistic effect of multiple ions effectively compensates for the shortcomings of single-ion materials in balancing photoelectric performance, stability, and flexibility, resulting in quasi-two-dimensional perovskite films that possess both high photoelectric activity and excellent mechanical tolerance.

[0024] In terms of solvent selection, N,N-dimethylformamide (DMF) and acetonitrile were mixed at a volume ratio of (4~9):1 as the solvent, achieving a precise balance between the solubility, viscosity, and evaporation rate of the precursor solution. DMF, as a highly polar solvent, is effective for FA... + MA + Cs +The multi-component ions possess extremely strong dissolving power, ensuring that each precursor component is fully dissolved to form a uniform and stable solution system. This avoids problems such as droplet aggregation and film defects caused by solute precipitation during the spraying process. Acetonitrile, with its low viscosity and high volatility, effectively regulates the overall viscosity and surface tension of the mixed solvent, giving the solution the fluidity suitable for the spraying process. This ensures that the spray gun can uniformly atomize the solution into tiny droplets, while avoiding uneven droplet spreading due to excessive viscosity or excessive droplet diffusion due to excessively low viscosity. The volume ratio of (4~9):1 is precisely optimized to ensure that the evaporation rate of the mixed solvent is perfectly coordinated with the subsequent heating temperature of the hot plate (60℃-110℃) and the spraying process. When the DMF ratio is within this range, it avoids problems such as coating sagging, component segregation, and uneven crystal growth caused by excessively high DMF content leading to slow solvent evaporation. At the same time, it also prevents defects such as coffee ring effect and insufficient crystal crystallization caused by excessively high acetonitrile content due to excessively rapid solvent evaporation. This solvent system ensures that the solvent evaporates quickly and uniformly after the droplets are sprayed onto the heated substrate surface, providing sufficient time for the nucleation and orderly growth of perovskite crystals, and guaranteeing the regularity and compactness of the crystal structure.

[0025] Regarding the selection of long-chain organic amines, n-butylamine ions or phenylethylamine ions were specifically chosen to further optimize the structure and properties of the quasi-two-dimensional perovskite. These two long-chain organic amine ions possess suitable chain lengths and chemical stability, enabling them to form good compatibility with other ionic components. They are arranged in an orderly manner within the crystal structure, neither damaging the photoelectric active sites of the perovskite nor hindering the flexibility and mechanical strength of the crystal structure through interactions between the long chains. Compared to other long-chain organic amines, n-butylamine and phenylethylamine ions can better regulate the interlayer forces of the quasi-two-dimensional perovskite, making the interlayer structure less prone to delamination during bending, curling, and other deformation processes, significantly improving the mechanical stability and service life of the film. Simultaneously, these two ions are chemically stable and will not decompose or react adversely with other components during preparation processes such as spraying and annealing, ensuring the stability of the precursor solution and the uniformity of the film composition. This provides a guarantee for preparing flexible perovskite films with consistent performance and high repeatability.

[0026] In summary, by precisely defining the key components of the precursor solution for preparing quasi-two-dimensional perovskites, a deep fit between material properties and the preparation process was achieved. This not only ensured that the quasi-two-dimensional perovskite films possessed high photoelectric conversion efficiency, good mechanical flexibility, and excellent stability, but also improved the controllability and repeatability of the preparation process. This lays a crucial foundation for the large-scale production of high-performance flexible perovskite devices and greatly expands the application prospects of flexible perovskite materials in photovoltaics, luminescence, and detection.

[0027] Preferably, in step S21, the nozzle and liquid path of the spray gun are immersed in DMF solution and ultrasonically cleaned for 30s~50s; S22. Fill the spray gun with 2mL~3mL of DMF and spray it all out; S23. Immerse the nozzle and liquid path of the spray gun in pure water and ultrasonically clean for 30s~50s; S24. Fill the spray gun with 2mL~3mL of pure water and spray it all out; S25. Immerse the nozzle and liquid path of the spray gun in ethanol and ultrasonically clean for 30s~50s. S26. Fill the spray gun with 2 mL to 3 mL of ethanol and spray it all out.

[0028] Step S21 employs ultrasonic cleaning of the spray gun with DMF solution, leveraging the synergistic advantages of DMF's strong solubility and ultrasonic cavitation effect. As one of the core solvents in the perovskite precursor solution, DMF possesses extremely strong dissolving power for residual perovskite precursors, organic components, and reaction byproducts, rapidly disintegrating stubborn residues adhering to the internal channels and nozzle walls of the spray gun. The high-frequency vibrations generated by ultrasonic cleaning form cavitation bubbles; the impact force generated when these bubbles burst can penetrate deep into the tiny pores and crevices of the spray gun, thoroughly removing contaminants hidden in dead corners. Compared to conventional rinsing, the cleaning depth and thoroughness are significantly improved, preventing residual contaminants from mixing into the perovskite precursor solution during subsequent coating processes and eliminating defects such as impurities, pinholes, and spots in the film.

[0029] Step S22 involves injecting a predetermined volume of DMF into the spray gun and then spraying it all out, forming a closed-loop cleaning cycle of rinsing and discharging. This step further flushes the internal tubing and nozzles of the spray gun, thoroughly removing contaminants suspended in the solution after ultrasonic cleaning and any residues that have not completely detached from the tubing walls. This ensures unobstructed flow within the spray gun's internal channels and verifies the smoothness of the spray gun's spraying function. The secondary rinsing and discharging of DMF not only reinforces the cleaning effect of ultrasonic cleaning but also prevents uneven liquid flow caused by residual contaminants in the tubing, laying the foundation for stable atomization and uniform spraying of the subsequent precursor solution.

[0030] Steps S23 and S24, involving immersion in pure water and rinsing with pure water jets, achieve highly efficient removal of DMF residue. Pure water, as a polar solvent, is fully miscible with DMF. Immersion dissolves DMF residue adhering to the inner wall of the spray gun, and the residue is then sprayed out, thoroughly removing DMF from the pipeline. This design prevents DMF residue from interacting with the subsequent perovskite precursor solution, thus preventing issues with solution viscosity and component stability. It also eliminates abnormal film surface tension caused by DMF residue, ensuring the normal spreading and crystallization of the precursor solution on the charge transport layer surface.

[0031] The ethanol immersion and ethanol spray cleaning in steps S25 and S26 leverage the advantages of ethanol's low viscosity and high volatility. Ethanol can dissolve small amounts of organic residues not removed by DMF and pure water, further improving the cleanliness of the spray gun. Simultaneously, ethanol's volatile nature quickly removes residual moisture from the inside of the spray gun, preventing water residue from causing hydrolysis or deterioration of the perovskite precursor solution, or from causing droplet aggregation and uneven film formation during spraying. After the ethanol is sprayed out, the inside of the spray gun is dry and clean. Combined with the subsequent oven drying step, this ensures the spray gun is completely free of moisture and residue, providing a pure equipment environment for the stable storage and spraying of the perovskite precursor solution.

[0032] The entire cleaning process employs a step-by-step design: DMF ultrasonic deep cleaning → DMF jet rinsing → DMF removal via pure water dissolution → ethanol finishing and drying. This achieves layered removal and residue control of contaminants on the spray gun. Each step performs its specific function and works in concert, ensuring both comprehensive and thorough cleaning while avoiding interference between different cleaning media. This ensures the spray gun remains clean, dry, and functionally stable throughout its operation. This refined cleaning process not only guarantees the consistency of film quality and performance in each preparation cycle but also extends the service life of the spray gun, reduces experimental errors and product defects caused by equipment contamination, and provides crucial equipment support for the large-scale and standardized preparation of flexible perovskite films, further enhancing the reliability and repeatability of the overall preparation process.

[0033] Preferably, in step S3, the flexible conductive substrate is treated in an ultraviolet ozone environment for 10-30 minutes. In step S4, the flexible conductive substrate and the charge transport layer are treated with ultraviolet ozone for 10-30 minutes. In step S6, the annealing time of the flexible perovskite coating is 1 min to 10 min, and nitrogen gas is sprayed onto the perovskite coating during annealing. In step S9, the annealing temperature of the flexible perovskite film is 90℃~110℃, and the annealing time is 30min~120min.

[0034] A 10-30 minute UV ozone treatment provides a high-quality interface foundation for the efficient bonding of the flexible conductive substrate and the charge transport layer. This duration allows for full utilization of the surface modification effect of UV ozone: on the one hand, the active oxygen species generated by the synergy of UV light and ozone can efficiently oxidize trace organic pollutants on the substrate surface, decomposing them into carbon dioxide and water, which then detach from the substrate surface, achieving deep interface cleaning and preventing pollutants from becoming defect sites in the subsequent film formation process; on the other hand, continuous UV ozone treatment can effectively improve the hydrophilicity and surface energy of the substrate surface, reduce the contact angle between the charge transport layer material and the substrate, and promote the uniform spreading and dense deposition of the transport layer material on the substrate surface. The minimum treatment time of 10 minutes ensures sufficient modification effect, avoiding problems such as poor interfacial compatibility and weak adhesion of the transport layer due to insufficient treatment; the maximum treatment time of 30 minutes can prevent over-treatment from affecting the conductivity or structural integrity of the substrate, achieving a balance between modification effect and substrate protection, and providing a solid guarantee for the continuity and integrity of the charge transport layer.

[0035] A 10-30 minute UV ozone treatment was also applied to the flexible conductive substrate-charge transport layer composite structure, resulting in a secondary modified and optimized design that further improved the interfacial compatibility between the charge transport layer and the perovskite coating. After this treatment, the physicochemical properties of the charge transport layer surface were precisely controlled: the surface energy was further optimized, enabling the perovskite precursor solution to spread rapidly and uniformly on the transport layer surface, avoiding film-forming defects such as droplet aggregation and localized coverage gaps; simultaneously, the oxidation effect of UV ozone reduced the defect state density on the transport layer surface, lowering the charge transport resistance between the transport layer and the perovskite layer interface, laying the foundation for efficient carrier migration. Furthermore, the 10-30 minute treatment time synergistically with subsequent hot-stage heating and spray coating processes, resulting in a composite structure with high surface cleanliness and activity, promoting crystal nucleation and orderly growth of the perovskite precursor solution during curing, reducing grain boundary defects, and improving the crystallinity and structural stability of the film.

[0036] Two 10-30 minute UV ozone treatments established an interface optimization system spanning the substrate, charge transport layer, and perovskite layer. Through precise step-by-step modification, the interfacial compatibility between functional layers was progressively improved. This time limit ensured the modification depth and cleaning effect of each treatment while avoiding the negative effects of insufficient or excessive treatment, resulting in a tight interfacial bond between the substrate, charge transport layer, and perovskite layer, reducing interfacial voids and defects. This interface optimization effect directly improves the overall structural stability of the film, making it less prone to interlayer delamination or cracking in flexible applications such as bending and rolling. Simultaneously, the low-defect interfacial structure effectively suppresses carrier recombination, improves charge transport efficiency, and thus enhances the photoelectric properties of the flexible perovskite film. Furthermore, the fixed and appropriate treatment time provides good repeatability and controllability of the fabrication process, ensuring consistent interface quality and performance levels across different batches and areas of films.

[0037] Utilizing a heated stage for precise heating of the coating, the 1-10 minute in-situ annealing of the perovskite coating provides sufficient energy during the single-layer coating curing stage. This promotes the orderly arrangement of precursor molecules and rapid solvent evaporation, avoiding defects such as looseness and pinholes in the coating caused by insufficient crystallization. This duration ensures that the perovskite crystals initially form a regular structure, reducing lattice defects, while preventing over-curing and increased brittleness due to excessive annealing time. This ensures that the new coating can tightly fuse with the underlying layer during subsequent multi-layer spraying, preventing interlayer delamination.

[0038] Nitrogen purging during annealing rapidly displaces air from the perovskite coating surface and surrounding environment, isolating it from oxygen and moisture. The nitrogen purging flow accelerates the evaporation rate of residual solvents on and within the coating surface, resulting in more uniform evaporation. This avoids coating sagging and component segregation caused by slow solvent evaporation, or the "coffee ring effect" caused by excessively rapid local evaporation, ensuring the orderly arrangement of perovskite precursor molecules and improving coating density. The nitrogen flow also removes trace reaction byproducts generated during annealing, reducing interference from impurities on crystal nucleation and growth. Simultaneously, the slight disturbance generated by the flow promotes precursor molecule diffusion, contributing to the formation of larger, more regular grains, reducing grain boundary defects, and improving charge transport efficiency. Nitrogen purging allows for a tighter interfacial contact between the perovskite coating and the underlying charge transport layer during curing, reducing interfacial voids. This not only improves coating adhesion, preventing interlayer delamination during subsequent multi-layer coating or device use, but also reduces interfacial charge transport resistance, optimizing the overall photoelectric performance of the thin film.

[0039] Annealing the perovskite thin film at a temperature of 90℃-110℃ provides sufficient energy for perovskite crystal growth, promoting grain refinement and growth, reducing internal voids and lattice defects, improving crystal alignment regularity, and thus enhancing the film's charge transport capability. An annealing time of 30min-120min effectively releases the internal stress accumulated during the layering and curing process, preventing cracking or performance degradation in flexible applications such as bending and curling, thus balancing high crystallinity with good mechanical flexibility.

[0040] Preferably, the thickness of each layer of the flexible perovskite coating is 200 nm to 5 μm.

[0041] The minimum thickness limit of 200 nm avoids film formation defects caused by excessively thin single coatings. If the coating thickness is less than 200 nm, it is difficult to form a complete and continuous film after the perovskite precursor solution solidifies, easily leading to problems such as pinholes, cracks, and local voids. These defects can hinder charge transport and may also result in weak interlayer bonding, affecting the overall structural stability of the film. The minimum thickness of 200 nm ensures that after a single spray, the coating can completely cover the substrate or the surface of the next coating layer, forming a dense, defect-free continuous structure, laying a good foundation for subsequent multilayer stacking.

[0042] The 5μm thickness limit prevents uneven crystallization caused by excessively thick single coatings. If a single coating exceeds 5μm, the solvent in the perovskite precursor solution cannot evaporate quickly and uniformly, leading to surface curing while solvent remains internally. This can cause uneven crystal growth, component segregation, and even internal stress concentration and cracking. The 5μm maximum thickness matches the solvent evaporation rate and crystal nucleation and growth rhythm in the spraying process, ensuring uniform crystallization, a dense internal structure, and no obvious pores or stress defects during curing.

[0043] A single coating thickness of 200 nm to 5 μm enables a tight interfacial bond between adjacent coatings. Within this thickness range, the newly sprayed precursor solution can fully contact and wet the surface of the next cured coating layer, avoiding the problems of interlayer suspension caused by excessively thin coatings or clear interlayer interfaces and weak adhesion caused by excessively thick coatings. After multilayer coating is stacked, a flexible perovskite film with an integrated structure can be formed, improving the film's bending and tensile strength and reducing performance degradation caused by interlayer delamination in flexible applications.

[0044] From the perspective of photoelectric performance, a single coating thickness of 200 nm to 5 μm ensures sufficient growth of perovskite crystals. This thickness range provides ample space for the crystallization of the perovskite precursor, which is conducive to the formation of appropriately sized and regularly arranged grains, reducing grain boundary defects and improving carrier mobility and separation efficiency. At the same time, the uniform single coating thickness ensures the uniformity of light absorption by the film, avoiding incomplete light absorption or aggravated recombination of photogenerated carriers due to local thickness differences, thus providing structural support for efficient photoelectric conversion of the thin film.

[0045] According to another aspect of the invention, a flexible perovskite thin film prepared by the method is also provided.

[0046] According to another aspect of the present invention, a perovskite device is also provided, comprising, from bottom to top, a flexible conductive substrate, a first charge transport layer, a flexible perovskite thin film, a second charge transport layer, and an electrode layer, wherein the flexible perovskite thin film is prepared by the method described above, and: If the first charge transport layer is an electron transport layer, then the second charge transport layer is a hole transport layer; If the first charge transport layer is a hole transport layer, then the second charge transport layer is an electron transport layer; The electron transport layer is made of SnO2 or C. 60 ; The hole transport layer comprises an inorganic hole transport layer and an organic hole transport layer deposited on the surface of the inorganic hole transport layer, wherein the inorganic hole transport layer is NiO. X Furthermore, the inorganic hole transport layer is prepared by magnetron sputtering; the organic hole transport layer is PTAA or SAMs, and the organic hole transport layer is prepared by spin coating or spray coating.

[0047] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1) This invention discloses a method for preparing flexible perovskite thin films using a spray coating process. Ultrasonic cleaning and oven drying of the flexible conductive substrate effectively remove contaminants such as oil, dust, residual impurities, and moisture from the substrate surface. Ultrasonic cleaning, utilizing the cavitation effect generated by its high-frequency vibrations, can penetrate deep into the micropores of the substrate surface to complete the cleaning. Compared to conventional cleaning methods, it can more thoroughly remove attached contaminants, preventing impurities from forming defect sites during subsequent film formation. Oven drying ensures the substrate surface is completely dry, eliminating the interference of residual moisture on the preparation of the charge transport layer and the spreading and crystallization process of the perovskite precursor solution. This lays a clean and stable substrate foundation for the effective bonding and performance of subsequent functional layers, significantly improving the adhesion between the film and the substrate and reducing problems such as film detachment and cracking caused by substrate contamination or moisture.

[0048] 2) In the method for preparing flexible perovskite thin films by spraying according to the present invention, the cleaning and drying of the spray gun are crucial steps to ensure the consistency and purity of the perovskite thin film preparation. As the spray carrier for the precursor solution, the cleanliness of the internal channels and nozzles of the spray gun directly affects the atomization effect and spray uniformity of the solution. Targeted cleaning can thoroughly remove residual impurities and solution components from previous experiments from the spray gun, preventing these contaminants from mixing into the perovskite precursor solution being prepared, thereby ensuring solution purity and preventing problems such as impurities and defects in the film. Oven drying removes moisture from the inside of the spray gun and nozzles, preventing moisture from interacting with the precursor solution and altering its properties, or affecting the size and uniformity of the atomized droplets during spraying. This ensures the spray gun remains in a stable working state, providing equipment assurance for the uniform spraying of the subsequent solution.

[0049] 3) The method for preparing flexible perovskite thin films using a spray coating process of the present invention, employing a two-stage ultraviolet ozone treatment process, demonstrates key surface modification value. The first ultraviolet ozone treatment acts on the flexible conductive substrate, effectively improving the hydrophilicity and surface energy of the substrate surface, enhancing the interfacial compatibility between the substrate and the charge transport layer, promoting the uniform spreading and dense deposition of the charge transport layer material on the substrate surface, avoiding local voids and uneven thickness in the transport layer, and ensuring the continuity and integrity of the charge transport layer. The second ultraviolet ozone treatment, targeting the composite structure of the flexible conductive substrate and the charge transport layer, further optimizes the physicochemical properties of the charge transport layer surface, reducing its contact angle with the perovskite precursor solution, creating favorable conditions for uniform coverage of the perovskite solution. Simultaneously, the active oxygen species generated during the ultraviolet ozone treatment can oxidize and decompose trace organic pollutants on the substrate and transport layer surfaces, further improving interface cleanliness, reducing interface defects, thereby promoting efficient charge transport between interfaces, and ensuring the improvement of the overall photoelectric performance of the thin film.

[0050] 4) This invention provides a method for preparing flexible perovskite thin films using a spraying method. The perovskite precursor solution can be a three-dimensional solution or a precursor solution used for preparing quasi-two-dimensional perovskites. Three-dimensional perovskite materials possess excellent charge transport capabilities and high crystallinity, while quasi-two-dimensional perovskite materials exhibit good mechanical flexibility and environmental stability. By selecting different types of precursor solutions, the performance of the flexible perovskite thin film can be precisely controlled according to the actual application scenario, meeting the differentiated requirements of different devices for photoelectric conversion efficiency, mechanical bending performance, stability, etc. Simultaneously, both types of precursor solutions are well-suited to the spraying process, providing material support for the smooth progress of the subsequent film formation process.

[0051] 5) In the method for preparing flexible perovskite thin films by spraying according to the present invention, precise control of the spray gun's air pressure is key to achieving uniform distribution of atomized droplets. The spray air pressure directly affects the atomization effect, droplet size, and spray rate of the precursor solution. By controlling the pressure within a reasonable range, the perovskite precursor solution can be atomized into uniformly sized, densely distributed micro-droplets. These micro-droplets, after being sprayed onto the surface of the charge transport layer, can spread rapidly and uniformly, avoiding droplet aggregation and incomplete local coverage, ensuring that each perovskite coating layer forms a smooth and dense structure. Uniform atomized droplets also promote rapid and uniform solvent evaporation, reducing component segregation problems caused by differences in solvent evaporation rates, ensuring the component uniformity of the perovskite thin film, and thus improving the overall performance consistency of the film.

[0052] 6) The method for preparing flexible perovskite thin films by spraying according to the present invention, wherein the spray gun is paused and the perovskite precursor solution is cured to form a flexible perovskite coating, is a key optimization addressing the contradiction between the characteristics of flexible substrates and the spraying process. Flexible substrates have poor thermal conductivity and low surface energy. Traditional continuous spraying easily leads to the mixing of subsequent droplets with uncured precursor solution, causing problems such as solvent evaporation disorder and component segregation, and is prone to forming the "coffee ring effect" (solute enrichment at the droplet edge and concavity in the center). After pausing the spraying, the single-layer precursor solution can independently complete the curing process under the heating environment of the hot stage: the solvent evaporates at a controllable rate, and the precursor molecules are arranged in an orderly manner to form nuclei, avoiding crystallization interference caused by the superposition of multiple droplets. This process effectively suppresses the generation of defects such as pinholes, cracks, and component inhomogeneity, so that each initial coating layer has a dense and continuous structural feature, creating conditions for tight interlayer bonding during subsequent multilayer superposition, and significantly improving the structural integrity of the film.

[0053] The design of using a hot stage to anneal flexible perovskite coatings achieves integrated control of "film formation-crystallization," overcoming the challenge of improving crystal quality under the temperature limitations of flexible substrates. Traditional annealing often involves concentrated high-temperature treatment after full film formation, but the heat resistance limit of flexible substrates is usually below 150℃. High temperatures easily lead to substrate deformation and performance degradation, while low temperatures are insufficient to meet crystallization requirements. By performing in-situ annealing of the perovskite coating and utilizing continuous heating on a hot stage, the energy required for crystal growth is provided during the coating curing stage. On the one hand, it promotes the full diffusion and orderly stacking of precursor molecules, reduces lattice defects and grain boundary impedance, improves crystallinity and grain size, and provides an efficient channel for charge transport. On the other hand, in-situ annealing enables the coating to form a strong interaction with the charge transport layer during curing, enhancing interfacial adhesion and preventing interlayer delamination during subsequent multilayer stacking or device use.

[0054] 7) The present invention provides a method for preparing flexible perovskite thin films using a spraying method. The nitrogen gas purging and nitrogen spray gun process provides a clean environment for the crystallization and performance stability of the perovskite thin film. The gas above the hot stage may contain impurities such as oxygen and moisture, which can interact with the perovskite material, leading to film oxidation, degradation, and defects. Nitrogen gas purging quickly replaces the air above the hot stage, forming an inert gas protective atmosphere that effectively isolates oxygen and moisture, preventing oxidation or hydrolysis of the perovskite thin film during subsequent annealing and ensuring the film's chemical stability. Furthermore, the nitrogen spray gun further removes residual trace amounts of solvent and impurities from the film surface, while also improving surface smoothness and reducing surface defects. In addition, the gas flow generated during nitrogen spraying also assists in solvent evaporation, creating more favorable conditions for annealing.

[0055] 7) The present invention provides a method for preparing flexible perovskite thin films by spraying. Annealing further promotes the growth and grain refinement of perovskite crystals, reduces structural defects such as lattice defects and pores within the crystals, and improves the regularity of crystal arrangement, thereby enhancing the charge transport capacity and photoelectric conversion efficiency of the thin film. Simultaneously, the annealing process eliminates internal stress in the thin film, improving its mechanical stability and making it less prone to cracking or performance degradation during bending, curling, and other deformation processes. Furthermore, annealing further removes residual trace amounts of solvent from the film, avoiding the adverse effects of solvent residue on the film's performance and long-term stability, ensuring that the flexible perovskite thin film maintains stable performance during long-term use.

[0056] 8) A method for preparing flexible perovskite thin films by spraying according to the present invention, wherein a nitrogen spray gun is used to purge the flexible perovskite thin film, and the airflow dynamics act on the film that has not yet been fully cured, promoting solvent evaporation and crystallization, and physically smoothing the tiny undulations on the surface of the film, so that the film achieves nanoscale flatness during the crystallization process, providing an excellent interface for subsequent layer deposition. Attached Figure Description

[0057] Figure 1 This is a process flow diagram of a method for preparing flexible perovskite thin films by spraying according to the present invention; Figure 2 SEM image of the flexible perovskite film prepared in Example 3; Figure 3 SEM image of the flexible perovskite film prepared for comparison. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0059] Example 1 A method for preparing flexible perovskite thin films by spraying includes the following steps: S1. After ultrasonically cleaning the flexible conductive substrate in a cleaning solvent, place it in an oven to dry. S2. After cleaning the spray gun, place it in an oven to dry. The cleaning process for the spray gun is as follows: S21. Immerse the nozzle and liquid path of the spray gun in DMF solution and ultrasonically clean for 30 seconds. S22. Fill the spray gun with 2.5 mL of DMF and spray it all out; S23. Immerse the nozzle and liquid path of the spray gun in pure water and ultrasonically clean for 50 seconds. S24. Fill the spray gun with 2mL of pure water and spray it all out. S25. Immerse the nozzle and liquid path of the spray gun in ethanol and ultrasonically clean for 30 seconds. S26. Fill the spray gun with 2 mL of ethanol and spray it all out. S3. After the flexible conductive substrate is treated with ultraviolet ozone for 15 minutes, a charge transport layer is prepared on the flexible conductive substrate. The charge transport layer is an electron transport layer. S4. Place the flexible conductive substrate and the charge transport layer together in an ultraviolet ozone environment. After the charge transport layer is treated with ultraviolet ozone for 20 minutes, place the flexible conductive substrate and the charge transport layer together on a hot stage. The hot stage heats the charge transport layer to 60°C. S5. Load the perovskite precursor solution into the spray gun, wherein the perovskite precursor solution is a precursor solution for preparing three-dimensional perovskite, and the molar concentration of the precursor solution for preparing three-dimensional perovskite is 1 mol / L; the precursor solution for preparing three-dimensional perovskite contains FA. + MA + Cs + Pb 2+ The solvent used to prepare the precursor solution of three-dimensional perovskite is a mixture of N,N-dimethylformamide and acetonitrile, with a volume ratio of N,N-dimethylformamide to acetonitrile of 4:1.

[0060] S6. Control the spray gun's air pressure at 0.1 MPa. The spray gun evenly sprays the perovskite precursor solution onto the charge transport layer. Then, the spray gun pauses spraying. The perovskite precursor solution solidifies to form a flexible perovskite coating. The hot stage heats the flexible perovskite coating to anneal it. The thickness of the flexible perovskite coating is 300 nm. The annealing time of the flexible perovskite coating is 1 min. During annealing, nitrogen gas is sprayed from an air gun to assist the annealing of the flexible perovskite coating. S7. Control the spray pressure of the spray gun at 0.1MPa. The spray gun evenly sprays the perovskite precursor solution onto the flexible perovskite coating. The perovskite precursor solution solidifies to form a flexible perovskite coating with a thickness of 300nm. S8. Repeat step S7 until the flexible perovskite film composed of all the flexible perovskite coatings reaches 900nm. S9. First, purge the gas above the hot stage with nitrogen gas flow, then purge the flexible perovskite film with nitrogen spray gun, and finally anneal the flexible perovskite film. The annealing temperature of the flexible perovskite film is 100℃ and the annealing time is 90min. A flexible perovskite thin film is prepared using the method described above.

[0061] A perovskite device includes a flexible conductive substrate, a first charge transport layer, a flexible perovskite thin film, a second charge transport layer, and an electrode layer arranged sequentially from bottom to top. The flexible perovskite thin film is prepared by the method described above, and the first charge transport layer is an electron transport layer and the second charge transport layer is a hole transport layer. In this embodiment, the material of the electron transport layer is C. 60 ; The hole transport layer comprises an inorganic hole transport layer and an organic hole transport layer deposited on the surface of the inorganic hole transport layer, wherein the inorganic hole transport layer is NiO. X Furthermore, the inorganic hole transport layer is prepared by magnetron sputtering; the organic hole transport layer is PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]), and the organic hole transport layer is prepared by spin coating or spray coating.

[0062] Example 2 A method for preparing flexible perovskite thin films by spraying includes the following steps: S1. After ultrasonically cleaning the flexible conductive substrate in a cleaning solvent, place it in an oven to dry. S2. After cleaning the spray gun, place it in an oven to dry. The cleaning process for the spray gun is as follows: S21. Immerse the nozzle and liquid path of the spray gun in DMF solution and ultrasonically clean for 45 seconds. S22. Fill the spray gun with 2 mL of DMF and spray it all out. S23. Immerse the nozzle and liquid path of the spray gun in pure water and ultrasonically clean for 30 seconds. S24. Fill the spray gun with 3mL of pure water and spray it all out. S25. Immerse the nozzle and liquid path of the spray gun in ethanol and ultrasonically clean for 40 seconds. S26. Fill the spray gun with 3 mL of ethanol and spray it all out. S3. After the flexible conductive substrate is treated with ultraviolet ozone for 10 minutes, a charge transport layer is prepared on the flexible conductive substrate. The charge transport layer is a hole transport layer. S4. Place the flexible conductive substrate and the charge transport layer together in an ultraviolet ozone environment. After the charge transport layer is treated with ultraviolet ozone for 10 minutes, place the flexible conductive substrate and the charge transport layer together on a hot stage. The hot stage heats the charge transport layer to 100°C. S5. Load the perovskite precursor solution into the spray gun, wherein the perovskite precursor solution is a precursor solution for preparing three-dimensional perovskite, and the molar concentration of the precursor solution for preparing three-dimensional perovskite is 0.8 mol / L; the precursor solution for preparing three-dimensional perovskite contains FA. + MA + Cs + Pb 2+ The solvent used to prepare the precursor solution of three-dimensional perovskite is a mixture of N,N-dimethylformamide and acetonitrile, with a volume ratio of N,N-dimethylformamide to acetonitrile of 6:1.

[0063] S6. Control the spray gun's air pressure at 0.2MPa. The spray gun evenly sprays the perovskite precursor solution onto the charge transport layer. Then, the spray gun pauses spraying. The perovskite precursor solution solidifies to form a flexible perovskite coating. The hot stage heats the flexible perovskite coating to anneal it. The thickness of the flexible perovskite coating is 200nm. The annealing time of the flexible perovskite coating is 3min. During annealing, nitrogen gas is sprayed from an air gun to assist the annealing of the flexible perovskite coating. S7. Control the spray pressure of the spray gun at 0.2MPa. The spray gun evenly sprays the perovskite precursor solution onto the flexible perovskite coating. The perovskite precursor solution solidifies to form a flexible perovskite coating with a thickness of 200nm. S8. Repeat step S7 until the flexible perovskite film composed of all the flexible perovskite coatings reaches 1 μm. S9. First, purge the gas above the hot stage with a nitrogen gas flow, then purge the flexible perovskite film with a nitrogen spray gun, and finally anneal the flexible perovskite film. The annealing temperature of the flexible perovskite film is 90℃ and the annealing time is 120min.

[0064] A flexible perovskite thin film is prepared using the method described above.

[0065] A perovskite device includes a flexible conductive substrate, a first charge transport layer, a flexible perovskite thin film, a second charge transport layer, and an electrode layer arranged sequentially from bottom to top. The flexible perovskite thin film is prepared by the method described above, and the first charge transport layer is a hole transport layer and the second charge transport layer is an electron transport layer. In this embodiment, the material of the electron transport layer is SnO2; The hole transport layer comprises an inorganic hole transport layer and an organic hole transport layer deposited on the surface of the inorganic hole transport layer, wherein the inorganic hole transport layer is NiO. X Furthermore, the inorganic hole transport layer is prepared by magnetron sputtering; the organic hole transport layer is a self-assembled monolayer (SAMs), specifically 2PACz ([2-(9H-carbazole-9-yl)ethyl]phosphonic acid), and the organic hole transport layer is prepared by spin coating or spray coating.

[0066] Example 3 A method for preparing flexible perovskite thin films by spraying includes the following steps: S1. After ultrasonically cleaning the flexible conductive substrate in a cleaning solvent, place it in an oven to dry. S2. After cleaning the spray gun, place it in an oven to dry. The cleaning process for the spray gun is as follows: S21. Immerse the nozzle and liquid path of the spray gun in DMF solution and ultrasonically clean for 50 seconds. S22. Fill the spray gun with 3 mL of DMF and spray it all out. S23. Immerse the nozzle and liquid path of the spray gun in pure water and ultrasonically clean for 30 seconds. S24. Fill the spray gun with 2.5 mL of pure water and spray it all out. S25. Immerse the nozzle and liquid path of the spray gun in ethanol and ultrasonically clean for 50 seconds. S26. Fill the spray gun with 2.6 mL of ethanol and spray it all out. S3. After the flexible conductive substrate is treated with ultraviolet ozone for 30 minutes, a charge transport layer is prepared on the flexible conductive substrate. The charge transport layer is an electron transport layer. S4. Place the flexible conductive substrate and the charge transport layer together in an ultraviolet ozone environment. After the charge transport layer is treated with ultraviolet ozone for 30 minutes, place the flexible conductive substrate and the charge transport layer together on a hot stage. The hot stage heats the charge transport layer to 110°C. S5. Load the perovskite precursor solution into the spray gun, wherein the perovskite precursor solution is a precursor solution for preparing three-dimensional perovskite, and the molar concentration of the precursor solution for preparing three-dimensional perovskite is 2 mol / L; the precursor solution for preparing three-dimensional perovskite contains FA. + MA + Cs + Pb 2+ The solvent used to prepare the precursor solution of three-dimensional perovskite is a mixture of N,N-dimethylformamide and acetonitrile, with a volume ratio of N,N-dimethylformamide to acetonitrile of 9:1.

[0067] S6. Control the spray gun's air pressure at 0.3MPa. The spray gun evenly sprays the perovskite precursor solution onto the charge transport layer. Then, the spray gun pauses spraying. The perovskite precursor solution solidifies to form a flexible perovskite coating. The hot table heats the flexible perovskite coating to anneal it. The thickness of the flexible perovskite coating is 1μm. The annealing time of the flexible perovskite coating is 10min. During annealing, nitrogen gas is sprayed from an air gun to assist the annealing of the flexible perovskite coating. S7. Control the spray pressure of the spray gun at 0.3MPa. The spray gun evenly sprays the perovskite precursor solution onto the flexible perovskite coating. The perovskite precursor solution solidifies to form a flexible perovskite coating with a thickness of 1μm. S8. Repeat step S7 until the flexible perovskite film composed of all the flexible perovskite coatings reaches 4μm. S9. First, purge the gas above the hot stage with a nitrogen gas flow, then purge the flexible perovskite film with a nitrogen spray gun, and finally anneal the flexible perovskite film. The annealing temperature of the flexible perovskite film is 110℃ and the annealing time is 30min.

[0068] A flexible perovskite thin film is prepared using the method described above.

[0069] A perovskite device includes a flexible conductive substrate, a first charge transport layer, a flexible perovskite thin film, a second charge transport layer, and an electrode layer arranged sequentially from bottom to top. The flexible perovskite thin film is prepared by the method described above, and if the first charge transport layer is an electron transport layer, then the second charge transport layer is a hole transport layer. In this embodiment, the material of the electron transport layer is C. 60 ; The hole transport layer comprises an inorganic hole transport layer and an organic hole transport layer deposited on the surface of the inorganic hole transport layer, wherein the inorganic hole transport layer is NiO. X Furthermore, the inorganic hole transport layer is prepared by magnetron sputtering; the organic hole transport layer is a self-assembled monolayer (SAMs), specifically Me-4PACz ([4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid), and the organic hole transport layer is prepared by spin coating or spray coating.

[0070] Example 4 A method for preparing flexible perovskite thin films by spraying includes the following steps: S1. After ultrasonically cleaning the flexible conductive substrate in a cleaning solvent, place it in an oven to dry. S2. After cleaning the spray gun, place it in an oven to dry. The cleaning process for the spray gun is as follows: S21. Immerse the nozzle and liquid path of the spray gun in DMF solution and ultrasonically clean for 30 seconds. S22. Fill the spray gun with 2.5 mL of DMF and spray it all out; S23. Immerse the nozzle and liquid path of the spray gun in pure water and ultrasonically clean for 50 seconds. S24. Fill the spray gun with 2mL of pure water and spray it all out. S25. Immerse the nozzle and liquid path of the spray gun in ethanol and ultrasonically clean for 30 seconds. S26. Fill the spray gun with 2 mL of ethanol and spray it all out. S3. After the flexible conductive substrate is treated with ultraviolet ozone for 20 minutes, a charge transport layer is prepared on the flexible conductive substrate. The charge transport layer is an electron transport layer. S4. Place the flexible conductive substrate and the charge transport layer together in an ultraviolet ozone environment. After the charge transport layer is treated with ultraviolet ozone for 10 minutes, place the flexible conductive substrate and the charge transport layer together on a hot stage. The hot stage heats the charge transport layer to 60°C. S5. Load the perovskite precursor solution into the spray gun, wherein the perovskite precursor solution is a precursor solution for preparing quasi-two-dimensional perovskite, and the n value of the prepared quasi-two-dimensional perovskite is 11, where n is the number of inorganic layers. The precursor solution used to prepare quasi-two-dimensional perovskite contains FA. + MA + Cs + Pb 2+The solvent used to prepare the precursor solution of the quasi-two-dimensional perovskite is a mixture of N,N-dimethylformamide and acetonitrile, with a volume ratio of N,N-dimethylformamide to acetonitrile of 5:1. The long-chain organic amine is n-butylamine ion.

[0071] S6. Control the spray gun's spray pressure at 0.1 MPa. The spray gun evenly sprays the perovskite precursor solution onto the charge transport layer. Then, the spray gun pauses spraying. The perovskite precursor solution solidifies to form a flexible perovskite coating. The hot stage heats the flexible perovskite coating to anneal it. The thickness of the flexible perovskite coating is 200 nm. The annealing time of the flexible perovskite coating is 1 min. During annealing, nitrogen gas is sprayed from an air gun to assist the annealing of the flexible perovskite coating. S7. Control the spray pressure of the spray gun at 0.1MPa. The spray gun evenly sprays the perovskite precursor solution onto the flexible perovskite coating. The perovskite precursor solution solidifies to form a flexible perovskite coating with a thickness of 200nm. S8. Repeat step S7 until the flexible perovskite film composed of all the flexible perovskite coatings reaches 800nm. S9. First, purge the gas above the hot stage with a nitrogen gas flow, then purge the flexible perovskite film with a nitrogen spray gun, and finally anneal the flexible perovskite film. The annealing temperature of the flexible perovskite film is 100℃ and the annealing time is 90min.

[0072] A flexible perovskite thin film is prepared using the method described above.

[0073] A perovskite device includes, from bottom to top, a flexible conductive substrate, a first charge transport layer, a flexible perovskite thin film, a second charge transport layer, and an electrode layer, wherein the flexible perovskite thin film is prepared by the method described above, and the first charge transport layer is an electron transport layer and the second charge transport layer is a hole transport layer.

[0074] In this embodiment, the material of the electron transport layer is SnO2; The hole transport layer comprises an inorganic hole transport layer and an organic hole transport layer deposited on the surface of the inorganic hole transport layer, wherein the inorganic hole transport layer is NiO. X Furthermore, the inorganic hole transport layer is prepared by magnetron sputtering; the organic hole transport layer is a self-assembled monolayer (SAMs), specifically Br-2PACz ([2-(3-bromo-9H-carbazole-9-yl)ethyl]phosphonic acid), and the organic hole transport layer is prepared by spin coating or spray coating.

[0075] Example 5 A method for preparing flexible perovskite thin films by spraying includes the following steps: S1. After ultrasonically cleaning the flexible conductive substrate in a cleaning solvent, place it in an oven to dry. S2. After cleaning the spray gun, place it in an oven to dry. The cleaning process for the spray gun is as follows: S21. Immerse the nozzle and liquid path of the spray gun in DMF solution and ultrasonically clean for 45 seconds. S22. Fill the spray gun with 2 mL of DMF and spray it all out. S23. Immerse the nozzle and liquid path of the spray gun in pure water and ultrasonically clean for 30 seconds. S24. Fill the spray gun with 2.4 mL of pure water and spray it all out. S25. Immerse the nozzle and liquid path of the spray gun in ethanol and ultrasonically clean for 50 seconds. S26. Fill the spray gun with 3 mL of ethanol and spray it all out. S3. After the flexible conductive substrate is treated with ultraviolet ozone for 10 minutes, a charge transport layer is prepared on the flexible conductive substrate. The charge transport layer is a hole transport layer. S4. Place the flexible conductive substrate and the charge transport layer together in an ultraviolet ozone environment. After the charge transport layer is treated with ultraviolet ozone for 15 minutes, place the flexible conductive substrate and the charge transport layer together on a hot stage. The hot stage heats the charge transport layer to 80°C. S5. Load the perovskite precursor solution into the spray gun, wherein the perovskite precursor solution is a precursor solution for preparing quasi-two-dimensional perovskite, and the n value of the prepared quasi-two-dimensional perovskite is 16, where n is the number of inorganic layers. The precursor solution used to prepare quasi-two-dimensional perovskite contains FA. + MA + Cs + Pb 2+ The solvent used to prepare the precursor solution of the quasi-two-dimensional perovskite is a mixture of N,N-dimethylformamide and acetonitrile, with a volume ratio of N,N-dimethylformamide to acetonitrile of 4:1. The long-chain organic amine is phenylethylamine ion.

[0076] S6. Control the spray gun's air pressure at 0.15MPa. The spray gun evenly sprays the perovskite precursor solution onto the charge transport layer. Then, the spray gun pauses spraying. The perovskite precursor solution solidifies to form a flexible perovskite coating. The hot table heats the flexible perovskite coating to anneal it. The thickness of the flexible perovskite coating is 1.2μm. The annealing time of the flexible perovskite coating is 3min. During annealing, nitrogen gas is sprayed from an air gun to assist the annealing of the flexible perovskite coating. S7. Control the spray gun's air pressure at 0.15MPa. The spray gun evenly sprays the perovskite precursor solution onto the flexible perovskite coating. The perovskite precursor solution solidifies to form a flexible perovskite coating with a thickness of 1.2μm. S8. Repeat step S7 until the flexible perovskite film composed of all the flexible perovskite coatings reaches 3.6 μm. S9. First, purge the gas above the hot stage with a nitrogen gas flow, then purge the flexible perovskite film with a nitrogen spray gun, and finally anneal the flexible perovskite film. The annealing temperature of the flexible perovskite film is 90℃ and the annealing time is 120min.

[0077] A flexible perovskite thin film is prepared using the method described above.

[0078] A perovskite device includes a flexible conductive substrate, a first charge transport layer, a flexible perovskite thin film, a second charge transport layer, and an electrode layer arranged sequentially from bottom to top. The flexible perovskite thin film is prepared by the method described above, and the first charge transport layer is a hole transport layer and the second charge transport layer is an electron transport layer. In this embodiment, the material of the electron transport layer is C. 60 ; The hole transport layer comprises an inorganic hole transport layer and an organic hole transport layer deposited on the surface of the inorganic hole transport layer, wherein the inorganic hole transport layer is NiO. X Furthermore, the inorganic hole transport layer is prepared by magnetron sputtering; the organic hole transport layer is a self-assembled monolayer (SAMs), specifically V-PACz ([2-(3,6-bis(4-vinylphenyl)-9H-carbazole-9-yl)ethyl]phosphonic acid), and the organic hole transport layer is prepared by spin coating or spray coating.

[0079] Example 6 A method for preparing flexible perovskite thin films by spraying includes the following steps: S1. After ultrasonically cleaning the flexible conductive substrate in a cleaning solvent, place it in an oven to dry. S2. After cleaning the spray gun, place it in an oven to dry. The cleaning process for the spray gun is as follows: S21. Immerse the nozzle and liquid path of the spray gun in DMF solution and ultrasonically clean for 50 seconds. S22. Fill the spray gun with 3 mL of DMF and spray it all out. S23. Immerse the nozzle and liquid path of the spray gun in pure water and ultrasonically clean for 30 seconds. S24. Fill the spray gun with 3mL of pure water and spray it all out. S25. Immerse the nozzle and liquid path of the spray gun in ethanol and ultrasonically clean for 40 seconds. S26. Fill the spray gun with 2.6 mL of ethanol and spray it all out. S3. After the flexible conductive substrate is treated with ultraviolet ozone for 30 minutes, a charge transport layer is prepared on the flexible conductive substrate. The charge transport layer is a hole transport layer. S4. Place the flexible conductive substrate and the charge transport layer together in an ultraviolet ozone environment. After the charge transport layer is treated with ultraviolet ozone for 30 minutes, place the flexible conductive substrate and the charge transport layer together on a hot stage. The hot stage heats the charge transport layer to 110°C. S5. Load the perovskite precursor solution into the spray gun, wherein the perovskite precursor solution is a precursor solution for preparing quasi-two-dimensional perovskite, and the n value of the prepared quasi-two-dimensional perovskite is 31, where n is the number of inorganic layers. The precursor solution used to prepare quasi-two-dimensional perovskite contains FA. + MA + Cs + Pb 2+ The solvent used to prepare the precursor solution of the quasi-two-dimensional perovskite is a mixture of N,N-dimethylformamide and acetonitrile, with a volume ratio of N,N-dimethylformamide to acetonitrile of 9:1. The long-chain organic amine is phenylethylamine ion.

[0080] S6. Control the spray gun's air pressure at 0.3MPa. The spray gun evenly sprays the perovskite precursor solution onto the charge transport layer. Then, the spray gun pauses spraying. The perovskite precursor solution solidifies to form a flexible perovskite coating. The hot table heats the flexible perovskite coating to anneal it. The thickness of the flexible perovskite coating is 5μm. The annealing time of the flexible perovskite coating is 10min. During annealing, nitrogen gas is sprayed from an air gun to assist the annealing of the flexible perovskite coating. S7. Control the spray gun's air pressure at 0.3MPa. The spray gun evenly sprays the perovskite precursor solution onto the flexible perovskite coating. The perovskite precursor solution solidifies to form a flexible perovskite coating with a thickness of 5μm. S8. Repeat step S7 until the flexible perovskite film composed of all the flexible perovskite coatings reaches 15 μm. S9. First, purge the gas above the hot stage with a nitrogen gas flow, then purge the flexible perovskite film with a nitrogen spray gun, and finally anneal the flexible perovskite film. The annealing temperature of the flexible perovskite film is 110℃ and the annealing time is 30min.

[0081] A flexible perovskite thin film is prepared using the method described above.

[0082] A perovskite device includes a flexible conductive substrate, a first charge transport layer, a flexible perovskite thin film, a second charge transport layer, and an electrode layer arranged sequentially from bottom to top. The flexible perovskite thin film is prepared by the method described above, and the first charge transport layer is a hole transport layer and the second charge transport layer is an electron transport layer. In this embodiment, the material of the electron transport layer is SnO2; The hole transport layer comprises an inorganic hole transport layer and an organic hole transport layer deposited on the surface of the inorganic hole transport layer, wherein the inorganic hole transport layer is NiO. X Furthermore, the inorganic hole transport layer is prepared by magnetron sputtering; the organic hole transport layer is PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]), and the organic hole transport layer is prepared by spin coating or spray coating.

[0083] Comparative Example Its process steps are basically the same as those in Example 3, except that: In step S4, the hot stage heats the charge transport layer to 45°C; In step S5, the concentration is 0.6 mol / L; In steps S6 and S7, the spray pressure of the spray gun is controlled at 0.05 MPa.

[0084] The SEM images of the typical Example 3 and the comparative example are selected, and the image analysis report is presented.

[0085] 1) Grain growth and crystallization quality Figure 2 (Example 3): As can be seen from the cross-sectional view, the perovskite grains exhibit a clear longitudinal growth trend, with huge grain sizes, and some grains even extending through the entire thickness of the film. This columnar crystal structure means that there are very few grain boundaries, which can effectively reduce the recombination probability of charge carriers during the transport process and greatly improve the charge transport efficiency.

[0086] Figure 3 (Comparative Example): The grains are fine and fragmented, exhibiting a multi-layered stacking structure. This is a typical manifestation of incomplete crystallization; numerous grain boundaries will form recombination centers, severely hindering current conduction and leading to low device efficiency.

[0087] 2) Thin film density and porosity Figure 2 (Example 3): The film is very dense inside, with almost no pinholes or obvious gaps. This is due to the high precursor solution concentration and suitable jetting pressure in Example 3, which ensured that the droplets spread evenly on the substrate and solidified rapidly to form a continuous film layer.

[0088] Figure 3(Comparative Example): Several large holes were observed in the cross-section (irregular black areas in the figure). This is mainly because the solution concentration in the comparative example was too low (0.6 mol / L) and the injection pressure was insufficient (0.05 MPa), resulting in the precursor content failing to cover the substrate, uneven droplet atomization, and the formation of severe structural defects after solvent evaporation.

[0089] 3) Interface contact and surface flatness Figure 2 (Example 3): The interface between the perovskite absorber layer and the charge transport layer below is clear and tight, and the upper surface is flat. This proves that the heating temperature of 110°C and the ultraviolet ozone treatment achieve excellent interface modification, which is beneficial to the subsequent deposition of the electrode layer.

[0090] Figure 3 (Comparative example): The surface has huge undulations and is uneven. This rough surface can lead to poor contact with the hole transport layer or electrode layer, resulting in serious leakage current and thus compromising the stability of the device.

[0091] Figure 2 The exhibited through-grain large and pinhole-free dense structure demonstrates that by precisely limiting the combination of jet pressure, precursor solution concentration and hot stage heating temperature, the performance of perovskite thin films can be significantly improved.

[0092] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing flexible perovskite thin films by spray coating, characterized in that, Includes the following steps: S1. After ultrasonically cleaning the flexible conductive substrate in a cleaning solvent, place it in an oven to dry. S2. After cleaning the spray gun, place it in an oven to dry. S3. After the flexible conductive substrate is treated with ultraviolet ozone, a charge transport layer is prepared on the flexible conductive substrate. The charge transport layer is an electron transport layer or a hole transport layer. S4. Place the flexible conductive substrate and the charge transport layer together in an ultraviolet ozone environment. After the charge transport layer is treated with ultraviolet ozone, place the flexible conductive substrate and the charge transport layer together on a hot stage. The hot stage heats the charge transport layer to a set temperature. S5. Load the perovskite precursor solution into the spray gun, wherein the perovskite precursor solution is a precursor solution for preparing three-dimensional perovskite or a precursor solution for preparing quasi-two-dimensional perovskite. S6. Control the spray pressure of the spray gun. The spray gun sprays the perovskite precursor solution evenly onto the charge transport layer. Then the spray gun stops spraying. The perovskite precursor solution solidifies to form a flexible perovskite coating. The hot table heats the flexible perovskite coating to anneal it. S7. Control the spray pressure of the spray gun. The spray gun evenly sprays the perovskite precursor solution onto the flexible perovskite coating. The perovskite precursor solution solidifies to form a flexible perovskite coating. S8. Repeat step S7 until the flexible perovskite film composed of all the flexible perovskite coatings reaches the set thickness. S9. First, purge the gas above the hot stage with a nitrogen gas flow, then purge the flexible perovskite film with a nitrogen spray gun, and finally anneal the flexible perovskite film.

2. The method for preparing flexible perovskite thin films by spraying according to claim 1, characterized in that, In step S4, the hot stage heats the charge transport layer to a set temperature of 60℃-110℃; In step S5, when the perovskite precursor solution is used to prepare a three-dimensional perovskite precursor solution, the molar concentration of the precursor solution used to prepare the three-dimensional perovskite is 0.8 mol / L–2 mol / L. In steps S6 and S7, the spray pressure of the spray gun is 0.1MPa-0.3MPa.

3. The method for preparing flexible perovskite thin films by spraying according to claim 2, characterized in that, The precursor solution used to prepare three-dimensional perovskite contains FA. + MA + Cs + Pb 2+ The solvent used to prepare the precursor solution of three-dimensional perovskite is a mixture of N,N-dimethylformamide and acetonitrile, and the volume ratio of N,N-dimethylformamide to acetonitrile is (4~9):

1.

4. The method for preparing flexible perovskite thin films by spraying according to claim 1, characterized in that, In step S4, the hot stage heats the charge transport layer to a set temperature of 60℃-110℃; In step S5, when the perovskite precursor solution is used to prepare a quasi-two-dimensional perovskite precursor solution, the n value of the prepared quasi-two-dimensional perovskite is 11~31, where n is the number of inorganic layers. In steps S6 and S7, the spray pressure of the spray gun is 0.1MPa-0.3MPa.

5. The method for preparing flexible perovskite thin films by spraying according to claim 4, characterized in that, The precursor solution used to prepare quasi-two-dimensional perovskite contains FA. + MA + Cs + Pb 2+ The solvent used to prepare the precursor solution of the quasi-two-dimensional perovskite is a mixture of N,N-dimethylformamide and acetonitrile, and the volume ratio of N,N-dimethylformamide to acetonitrile is (4~9):

1. The long-chain organic amine is n-butylamine ion or phenylethylamine ion.

6. The method for preparing flexible perovskite thin films by spraying according to claim 1, characterized in that, In step S2, the cleaning process of the spray gun is as follows: S21. Immerse the nozzle and liquid path of the spray gun in DMF solution and ultrasonically clean for 30s~50s; S22. Fill the spray gun with 2mL~3mL of DMF and spray it all out; S23. Immerse the nozzle and liquid path of the spray gun in pure water and ultrasonically clean for 30s~50s; S24. Fill the spray gun with 2mL~3mL of pure water and spray it all out; S25. Immerse the nozzle and liquid path of the spray gun in ethanol and ultrasonically clean for 30s~50s. S26. Fill the spray gun with 2 mL to 3 mL of ethanol and spray it all out.

7. The method for preparing flexible perovskite thin films by spraying according to claim 1, characterized in that, In step S3, the flexible conductive substrate is treated in an ultraviolet ozone environment for 10-30 minutes. In step S4, the flexible conductive substrate and the charge transport layer are treated with ultraviolet ozone for 10-30 minutes. In step S6, the annealing time of the flexible perovskite coating is 1 min to 10 min, and nitrogen gas is sprayed onto the perovskite coating during annealing. In step S9, the annealing temperature of the flexible perovskite film is 90℃~110℃, and the annealing time is 30min~120min.

8. The method for preparing flexible perovskite thin films by spraying according to claim 1, characterized in that, The thickness of each layer of the flexible perovskite coating is 200 nm to 5 μm.

9. A flexible perovskite thin film, characterized in that, It is prepared by the method described in any one of claims 1 to 8.

10. A perovskite device, comprising, from bottom to top, a flexible conductive substrate, a first charge transport layer, a flexible perovskite thin film, a second charge transport layer, and an electrode layer, characterized in that, The flexible perovskite thin film is prepared by the method described in any one of claims 1 to 8, and: If the first charge transport layer is an electron transport layer, then the second charge transport layer is a hole transport layer; If the first charge transport layer is a hole transport layer, then the second charge transport layer is an electron transport layer; The electron transport layer is made of SnO2 or C. 60 ; The hole transport layer comprises an inorganic hole transport layer and an organic hole transport layer deposited on the surface of the inorganic hole transport layer, wherein the inorganic hole transport layer is NiO. X Furthermore, the inorganic hole transport layer is prepared by magnetron sputtering; the organic hole transport layer is PTAA or SAMs, and the organic hole transport layer is prepared by spin coating or spray coating.

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