A method for preparing a perovskite thin film
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN FUGUANG PHOTOVOLTAIC CO LTD
- Filing Date
- 2026-02-06
- Publication Date
- 2026-06-02
Smart Images
Figure CN122138603A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of photovoltaic material preparation technology, specifically to a method for preparing perovskite thin films. Background Technology
[0002] Organic-inorganic hybrid perovskite materials have shown great potential in fields such as solar cells due to their excellent photoelectric properties. However, their industrialization is limited by efficient, uniform, and low-cost large-area fabrication processes.
[0003] Traditional solution-based methods, such as spin coating, suffer from significant material waste (utilization rate typically below 5%), difficulty in scaling up areas, and pronounced edge effects. While blade coating can be used for large-area preparation, it is extremely sensitive to process parameters (such as blade gap, speed, and solution viscosity), making it difficult to control film uniformity, and mechanical contact can introduce defects. Currently, there is a lack of a method for preparing perovskite thin films that can simultaneously achieve high material utilization, excellent film uniformity, good crystallinity, and is particularly suitable for meter-scale wide-width continuous production. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing perovskite thin films, so as to solve the problems of poor uniformity, low material utilization, and difficulty in scaling up the process when preparing large-area perovskite thin films in the prior art.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] In a first aspect, the present invention provides a method for preparing a perovskite thin film, comprising the following steps:
[0007] At least one metal halide layer is formed on the surface of the substrate by vapor deposition.
[0008] An ultrasonic spraying method is used to atomize and spray a precursor solution containing an organic ammonium salt onto the halide metal layer to form a wet film; and
[0009] The wet film is annealed to form a perovskite thin film.
[0010] Furthermore, the step of forming at least one metal halide layer includes:
[0011] First, a halide layer containing cesium and bromine is deposited by vapor deposition; and
[0012] On the cesium and bromine-containing halide layer, another lead and iodine-containing halide layer is deposited by vapor deposition.
[0013] Furthermore, the cation contained in the organic ammonium salt is selected from at least one of formamidinium cation and methylammonium cation.
[0014] Furthermore, the organic ammonium salt comprises a mixture of formamidinium iodide and methylammonium iodide.
[0015] Furthermore, the deposition rate of the vapor deposition method is 0.1-50 Å / s; the total thickness of the halide metal layer is 10-1000 nm.
[0016] Furthermore, the parameters of the ultrasonic spraying include: a nozzle-to-substrate distance of 20-50 mm, a spraying linear velocity of 1-50 mm / s, a solution injection rate of 0.1-1.0 mL / min, and an atomization power of 0.5-3.0 W.
[0017] Furthermore, in the ultrasonic spraying step, the temperature of the substrate is maintained in the range of 80°C to 120°C.
[0018] Furthermore, the ultrasonic spraying technology is achieved through a linear array comprising multiple nozzles.
[0019] Furthermore, the method for preparing the perovskite thin film includes the following steps:
[0020] (1) Preparation of precursor solution
[0021] The perovskite precursor material was dissolved in a polar solvent to prepare a uniform and stable precursor solution.
[0022] (2) Substrate pre-coating treatment
[0023] The substrate is cleaned, plasma treated, and then halide metal elements are deposited on it using a vapor deposition process.
[0024] (3) Ultrasonic spraying
[0025] The precursor solution in step (1) is loaded into the storage tank of the ultrasonic spraying equipment. The precursor solution is atomized into micron-sized precursor droplets by the ultrasonic atomizer and uniformly sprayed onto the substrate surface under the drive of the nozzle carrier gas.
[0026] (4) In-situ reaction and crystallization control
[0027] During or after spraying, by controlling the temperature of the carrier plate and the humidity of the atmosphere, the precursor droplets are encouraged to spread, fuse and react on the surface of the substrate to form a uniform wet film.
[0028] (5) Annealing treatment
[0029] The sprayed wet film is placed on a hot plate or in an oven for annealing to form perovskite crystals.
[0030] Beneficial effects
[0031] Compared with the prior art, the present invention has the following significant advantages:
[0032] 1. Process Synergy and Innovation: This technology creatively combines two processes with different physical mechanisms: high-vacuum evaporation and solution ultrasonic spraying. Evaporation first precisely and densely constructs an inorganic halide framework (B-site and X-site sources), providing an ideal template for subsequent reactions; non-contact ultrasonic spraying then gently and uniformly introduces organic components (A-site sources), forming perovskite through in-situ liquid-phase reactions. This combination is not a simple additive process, but rather produces a synergistic effect of "1+1>2," overcoming the limitations of single-process technologies.
[0033] 2. Excellent film uniformity over large areas: The non-contact nature of ultrasonic spraying avoids scratches or stress caused by mechanical contact such as scraping. Its atomized droplets are uniform and fine, and combined with the flat substrate of the vapor-deposited layer, it is easy to achieve highly uniform deposition of large-area (especially meter-wide) films. Comparative experiments show that the film thickness uniformity of the method of this invention is significantly better than that of spin coating on a 100mm×100mm area.
[0034] 3. High material utilization and low cost potential: Ultrasonic spraying can directionally deposit the solution onto the substrate, achieving a material utilization rate of over 70%, far exceeding that of spin coating (<5%). The material utilization rate in the vapor deposition process is also high. Overall, the process has low raw material loss, meeting the cost reduction requirements for industrialization.
[0035] 4. Wide applicability: This method has good substrate compatibility and can be used to form films on rigid (such as glass) and flexible (such as PET and PI) substrates, as well as substrates with micro- and nano-structures. The process parameter window is wide, making it easy to control film thickness and properties, and suitable for fabricating perovskite optoelectronic devices with different requirements. Attached Figure Description
[0036] Figure 1 The image shows the SEM surface morphology of the CsPbI2Br perovskite film prepared in Example 1.
[0037] Figure 2 The XRD patterns of the films prepared in Example 1 and Comparative Example 1 are compared, where 1 is Example 1 and 2 is Comparative Example 1. Detailed Implementation
[0038] To make the technical problems solved, technical solutions, and beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the embodiments described herein are only some, not all, embodiments of the present invention, and are merely illustrative and not intended to limit the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.
[0039] This invention provides a method for preparing a perovskite thin film, comprising the following steps: forming at least one metal halide layer on the surface of a substrate by vapor deposition; atomizing and spraying a precursor solution containing an organic ammonium salt onto the metal halide layer by ultrasonic spraying to form a wet film; and subjecting the wet film to heat treatment to crystallize and form a perovskite thin film.
[0040] The core of this preparation method lies in combining high-vacuum evaporation and solution ultrasonic spraying. First, a dense one or more halide metal inorganic frameworks are precisely constructed on the substrate surface using evaporation. Then, a non-contact ultrasonic spraying technique is employed to uniformly atomize and deposit a precursor solution containing an organic ammonium salt (A-site cation source) onto the inorganic framework. A wet film is formed through in-situ liquid-phase reaction, and finally, a uniform and dense perovskite thin film is obtained through heat treatment and crystallization. This method not only fully leverages the advantages of evaporation in controlling the thickness and purity of the inorganic layer, and the potential of ultrasonic spraying in high material utilization and large-area uniform film formation, but also overcomes the limitations of single processes through synergy. This provides an efficient, controllable, and low-cost thin film preparation solution for the industrialization of perovskite optoelectronic devices (such as solar cells).
[0041] It is understood that the substrate here refers to conductive glass (such as FTO / ITO) or a flexible substrate. Specifically, the halide metal layer contains a B-site metal cation and an X-site halide anion; the halide metal layer can be a stacked or mixed layer of one or more of lead iodide, lead bromide, lead chloride, cesium iodide, and cesium bromide. The precursor solution contains an A-site organic cation, and the halide metal layer reacts with the A-site organic cation precursor through heat treatment to crystallize and form an ABX3 type perovskite thin film.
[0042] In some specific embodiments, the step of forming at least one metal halide layer includes: first depositing a halide layer containing cesium and bromine; and then depositing a halide layer containing lead and iodine on the cesium and bromine halide layer. This stepwise deposition method of the metal halide layer (e.g., CsBr first, then PbI2) helps to form perovskite films with more controllable stoichiometry and higher crystallinity, and is particularly suitable for high-stability perovskite systems containing mixed halogens.
[0043] In some specific embodiments, the cation contained in the organic ammonium salt may be selected from at least one of formamidinium cation and methylammonium cation. More specifically, the organic ammonium salt contains a mixture of formamidinium iodide and methylammonium iodide. By using formamidinium cation, methylammonium cation, or a mixture thereof, the lattice size and photoelectric properties of perovskites can be flexibly adjusted, thereby improving the light absorption efficiency and long-term stability of the device.
[0044] This invention can regulate the thickness, uniformity, and crystallinity of the perovskite film by synergistically controlling the deposition rate of the vapor deposition method and the spraying parameters of the ultrasonic spraying method. In some specific embodiments, the deposition rate of the vapor deposition method is 0.1-50 Å / s; the total thickness of the halide metal layer is 10-1000 nm. By controlling the deposition rate and thickness, the deposition process of the inorganic framework is highly controllable, which is beneficial for achieving large-area uniform coatings with nanoscale precision, providing a smooth substrate with consistent chemical activity for subsequent spraying.
[0045] In some specific embodiments, the parameters of the ultrasonic spraying include: a nozzle-to-substrate distance of 20-50 mm, a spraying linear velocity of 1-50 mm / s, a solution infusion rate of 0.1-1.0 mL / min, and an atomization power of 0.5-3.0 W. Optimization of ultrasonic spraying parameters, including the coordination of nozzle distance, linear velocity, infusion rate, and atomization power, significantly improves the uniformity and deposition efficiency of precursor droplets, reduces sputtering and agglomeration, thereby obtaining a defect-free, high-quality wet film.
[0046] Preferably, in the ultrasonic spraying step, the temperature of the substrate is maintained within the range of 80°C to 120°C. Maintaining the substrate temperature at a suitable level promotes rapid solvent evaporation and initial reaction during spraying, avoids uneven droplet flow or excessive aggregation, and facilitates rapid and continuous film formation.
[0047] In some specific embodiments, the heat treatment is an annealing treatment. Preferably, the annealing treatment temperature is 100-200°C and the time is 10-120 minutes. More preferably, the annealing treatment temperature is in the range of 150°C to 190°C.
[0048] In some specific embodiments, the ultrasonic spraying technology is implemented through a linear array of multiple nozzles. Using a multi-nozzle linear array for ultrasonic spraying significantly improves the uniformity of the spray coverage and the process speed, making it particularly suitable for wide-area, continuous production scenarios and facilitating large-scale production.
[0049] In some specific embodiments, the method is executed sequentially in a continuous manner on roll-to-roll equipment. This continuous roll-to-roll execution method enables integrated continuous production of the entire process, from vapor deposition to spraying and annealing, significantly improving production efficiency, reducing manual intervention and batch variations, and making it suitable for the manufacturing of flexible electronics and large-area photovoltaic modules.
[0050] Specifically, the method for preparing a perovskite thin film provided by the present invention is described in detail below with more specific examples:
[0051] (1) Preparation of precursor solution
[0052] The perovskite precursor material, ammonium methyl ether salt, was dissolved in the polar solvent DMF to prepare a homogeneous and stable precursor solution.
[0053] (2) Substrate pre-coating treatment
[0054] The flexible substrate is cleaned and plasma treated to improve surface tension and adhesion. Then, a vapor deposition process is used to deposit halide metal elements such as lead iodide and cesium bromide.
[0055] (3) Ultrasonic spraying of methyl ether ammonium salt
[0056] The precursor solution from the first step is loaded into the storage tank of the ultrasonic spraying equipment. The solution is then atomized into micron-sized droplets by the ultrasonic atomizer and uniformly sprayed onto the substrate surface under the action of the carrier gas in the nozzle.
[0057] (4) In-situ reaction and crystallization control
[0058] During or after spraying, by controlling the temperature of the carrier plate and the humidity of the atmosphere, the precursor droplets are encouraged to spread, fuse and react on the surface of the substrate to form a uniform wet film.
[0059] (5) Annealing treatment
[0060] The sprayed wet film is placed on a hot plate or in an oven for annealing at 170°C for 1 hour to promote the complete crystallization of perovskite crystals to form the ABX3 crystal structure and densify the film layer.
[0061] (6) Morphological characteristics
[0062] The crystal structure after annealing can be further characterized at a microscopic level (e.g., polycrystalline X-ray diffraction, EDS, etc.), and other annealing schemes or interface modification processes can be used to optimize the crystal morphology and photoelectric properties.
[0063] The method is applicable to roll-to-roll continuous production processes, wherein the width of the substrate is ≥0.5 meters.
[0064] The present invention will be further described below through examples and comparative examples.
[0065] Example 1:
[0066] Preparation of CsPbI2Br perovskite thin films based on FTO substrate
[0067] (1) Preparation of precursor solution: Mix formamidinium iodide (FAI) and methylammonium iodide (MAI) at a mass ratio of 0.9:1, dissolve them in a mixed solvent of n-butanol and N-methylpyrrolidone (NMP) at a volume ratio of 99:1, stir until completely dissolved, and form a clear organic ammonium salt precursor solution.
[0068] (2) Substrate pre-coating treatment: FTO conductive glass was selected as the substrate, and after cleaning and plasma treatment, it was placed in a vacuum evaporation chamber. First, in a 1.6×10 -5 Under a high vacuum of kPa, a cesium bromide (CsBr, 99.99% purity) layer with a thickness of approximately 30 nm (controlled with an accuracy of ±10%) was deposited at a rate of 0.3–0.5 Å / s. Subsequently, without disrupting the vacuum, a lead iodide (PbI2, 99.99% purity) layer with a thickness of approximately 300 nm (controlled with an accuracy of ±10%) was deposited on top of the CsBr layer at a rate of 3.5 Å / s, thus forming a "CsBr / PbI2" bilayer halide metal structure. The substrate was rotated at 50 rpm throughout the process to ensure uniformity.
[0069] (3) Ultrasonic spraying: Inject the precursor solution prepared in step (1) into the ultrasonic spraying equipment. Set the nozzle-to-substrate distance to 38-40 mm, the solution injection rate to 0.28 mL / min, the ultrasonic atomization power to 1.0 W, the line spacing to 5 mm, and maintain the substrate temperature at 100℃. Control the nozzle to move along a specific path to uniformly spray the micron-sized droplets formed by atomization onto the 100×160 mm substrate coated with a double layer of metal halide. 2 Substrate surface.
[0070] (4) In-situ reaction and crystallization control: During the spraying process, the heating of the substrate (100℃) causes the precursor droplets to spread rapidly and the solvent to evaporate when they come into contact with the CsBr / PbI2 layer, and immediately triggers the solid-liquid interface reaction between FAI / MAI and the underlying metal halide to form a uniform perovskite wet film.
[0071] (5) Annealing treatment: The coated substrate is quickly transferred to a hot plate at 170°C (temperature control accuracy ±2°C) for annealing for 1 hour. This process promotes the complete transformation of the intermediate phase into the highly crystalline perovskite phase (Cs / FA / MA)Pb(I / Br)3. Figure 1 SEM images show that the film surface is dense and fully covered, with uniform grain size, averaging 4-5 micrometers. Within a 100 mm × 100 mm range, the film thickness uniformity (standard deviation) is better than ±5%, significantly better than spin coating processes of the same area.
[0072] Example 2:
[0073] Roll-to-roll continuous fabrication on flexible substrates
[0074] (1) Substrate and vapor deposition: Flexible polyethylene terephthalate (PET) substrate (500 mm wide) was selected and loaded into a roll-to-roll (R2R) vacuum vapor deposition equipment. Under high vacuum, a 50 nm thick layer of cesium bromide (CsBr) was first vapor deposited on the entire roll of substrate at a rate of 1.0 Å / s, followed by a 400 nm thick layer of lead iodide (PbI2).
[0075] (2) Integrated spraying and annealing: The vapor-deposited flexible substrate is continuously conveyed to an atmosphere-controlled R2R ultrasonic spraying chamber. The spraying unit uses linear array nozzles to uniformly spray a formamidinium iodide (FAI) isopropanol solution onto the moving substrate surface while maintaining the substrate temperature at 90°C. The sprayed wet film then enters the online hot air drying and annealing zone, where it is treated at 150°C for 30 minutes to complete crystallization.
[0076] (3) Results: This process enables continuous and high-speed preparation of meter-wide perovskite thin films. Thanks to the uniformity of non-contact spraying and vapor deposition of the pre-layer, the film quality is stable and the material utilization rate exceeds 70%, fully demonstrating the great potential of this method for industrialization.
[0077] Comparative Example 1:
[0078] This comparative example uses a traditional full evaporation deposition process as a reference. In a vacuum chamber, PbI2, CsBr, FAI, and MAI sources are co-deposited sequentially in an attempt to directly deposit a perovskite thin film. Although this method can form dense films, controlling the thermal evaporation temperature of the organic sources is difficult, easily leading to thermal decomposition, and precisely controlling the stoichiometric ratio of the multi-element co-evaporation is extremely challenging. Figure 2 It can be seen that, compared with Example 1, the final crystallization quality of the thin film obtained in Comparative Example 1 is poor.
[0079] Comparative Example 2:
[0080] This comparative example uses only ultrasonic spraying. All precursors containing PbI2, FAI, MAI, and CsI are dissolved in the same solvent to prepare a high-concentration solution, which is then directly sprayed onto a heated substrate. Since all components must crystallize from the solution in a single step, the requirements for solvent selection, drying kinetics, and crystallization process control are extremely stringent. It is impossible to form a connected, dense perovskite film. Experiments show that the resulting film has poor uniformity and is prone to pinholes and coarse grains. The film is island-like, porous, with low coverage, and inconsistent crystal orientation over a large area, resulting in low performance repeatability. This highlights the advantage of the present invention, which pre-deposits an inorganic framework via vapor deposition. This provides an ideal and uniform template for the subsequent introduction and reaction of the organic phase, greatly simplifying the difficulty of crystallization control.
[0081] In summary, this invention achieves complementary advantages through a step-by-step strategy of "evaporating an inorganic framework + spraying organic components." The embodiments demonstrate the effectiveness and superiority of this method in rigid / flexible substrates, different perovskite composition systems, and continuous production scenarios, while the comparative examples, from the opposite perspective, illustrate the inherent limitations of single traditional processes in this application scenario. This highlights the technical value and industrial application prospects of the innovative combination of this invention.
[0082] The above description is only 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 protection scope of the present invention.
Claims
1. A method for preparing a perovskite thin film, characterized in that, Includes the following steps: At least one metal halide layer is formed on the surface of the substrate by vapor deposition. An ultrasonic spraying method is used to atomize and spray a precursor solution containing organic ammonium salt onto the halide metal layer to form a wet film. as well as The wet film is subjected to heat treatment to crystallize and form a perovskite thin film.
2. The method for preparing a perovskite thin film according to claim 1, characterized in that, The step of forming at least one metal halide layer includes: First, a halide layer containing cesium and bromine is deposited by vapor deposition; and On the cesium and bromine-containing halide layer, another lead and iodine-containing halide layer is deposited by vapor deposition.
3. The method for preparing a perovskite thin film according to claim 1, characterized in that, The organic ammonium salt contains cations selected from at least one of formamidinium cations and methylammonium cations.
4. The method for preparing a perovskite thin film according to claim 1, characterized in that, The organic ammonium salt comprises a mixture of formamidinium iodide and methylammonium iodide.
5. The method for preparing a perovskite thin film according to claim 1, characterized in that, The deposition rate of the vapor deposition method is 0.1-50 Å / s; the total thickness of the halide metal layer is 10-1000 nm.
6. The method for preparing a perovskite thin film according to claim 1, characterized in that, The parameters of the ultrasonic spraying include: a nozzle-to-substrate distance of 20-50 mm, a spraying linear velocity of 1-50 mm / s, a solution injection rate of 0.1-1.0 mL / min, and an atomization power of 0.5-3.0 W.
7. The method for preparing a perovskite thin film according to claim 1, characterized in that, During the ultrasonic spraying step, the temperature of the substrate is maintained in the range of 80°C to 120°C.
8. The method for preparing a perovskite thin film according to claim 1, characterized in that, The ultrasonic spraying technology is achieved through a linear array containing multiple nozzles.
9. The method for preparing a perovskite thin film according to claim 1, characterized in that, Includes the following steps: (1) Preparation of precursor solution The perovskite precursor material was dissolved in a polar solvent to prepare a uniform and stable precursor solution. (2) Substrate pre-coating treatment The substrate is cleaned, plasma treated, and then halide metal elements are deposited on it using a vapor deposition process. (3) Ultrasonic spraying The precursor solution in step (1) is loaded into the storage tank of the ultrasonic spraying equipment. The precursor solution is atomized into micron-sized precursor droplets by the ultrasonic atomizer and uniformly sprayed onto the substrate surface under the drive of the nozzle carrier gas. (4) In-situ reaction and crystallization control During or after spraying, by controlling the temperature of the carrier plate and the humidity of the atmosphere, the precursor droplets are encouraged to spread, fuse and react on the surface of the substrate to form a uniform wet film. (5) Annealing treatment The sprayed wet film is placed on a hot plate or in an oven for annealing to form perovskite crystals.