Double-cutter-head coating device and method for preparing uniform perovskite thin film

Abstract

The invention discloses a double-cutter-head coating device and method for preparing a uniform perovskite thin film, and the coating device comprises a substrate platform which is used for placing a substrate; the double-tool-bit assembly has the freedom degree of horizontal movement relative to the substrate platform and is used for forming a perovskite thin film on the substrate; the driving mechanism is connected with the double-tool-bit assembly and used for driving the double-tool-bit assembly to move relative to the base plate platform in the horizontal direction; the double-tool-bit assembly comprises a first tool bit which is connected to the driving mechanism and is used for coating the surface of a substrate with a perovskite precursor solution to form a liquid film, and a second tool bit which is connected to the driving mechanism and is used for coating the surface of the substrate with the perovskite precursor solution. The second tool bit is connected to the driving mechanism and located on the downstream of the first tool bit, and the second tool bit and the first tool bit move synchronously and are used for applying a mechanical shearing effect to the liquid film; gaps between the first tool bit and the surface of the substrate and between the second tool bit and the surface of the substrate are H1 and H2 respectively, and H1 is larger than H2; the distance between the first tool bit and the second tool bit is L, the concentration of the perovskite precursor solution is rho, and L * rho is larger than or equal to 10 and smaller than or equal to 30.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of preparation of perovskite solar cells, and particularly relates to a double-tool-head coating device and method for preparing uniform perovskite thin films. BACKGROUND

[0002] Perovskite solar cells (PSCs) as a new generation of photovoltaic technology show great commercial prospects due to their high efficiency and low manufacturing cost. The key to moving from the experimental stage to industrialization is how to achieve high-performance, high-stability large-area module preparation. Among the many film preparation technologies, blade coating and slot coating are considered one of the most promising large-area film preparation technologies due to their simple process, compatibility with roll-to-roll production, and high material utilization rate.

[0003] However, during the coating process, rapid solvent evaporation can cause changes in local solution concentration and temperature, resulting in surface tension gradients and triggering Marangoni flow, which carries solutes (such as lead salts and organic ammonium salts in perovskite precursor solution) from the center of the film to the edge and deposits there, forming the so-called "Coffee-Ring Effect", which leads to uneven perovskite film thickness, component separation (such as PbI2 precipitation), large grain size differences, and other defects, which seriously restrict the improvement of large-area perovskite device performance and are the core bottleneck of industrialization.

[0004] Currently, existing technologies generally use pneumatic shearing (air knife) to suppress Marangoni flow, but its airflow field stability is easily disturbed by the environment and there is a risk of disturbing the liquid surface, so pneumatic shearing is not conducive to improving defects such as uneven film thickness, component separation, and large grain size differences in the process of preparing perovskite films. SUMMARY

[0005] The purpose of the present application is to design a double-tool-head coating device for preparing uniform perovskite thin films, which aims to solve the above problems caused by Marangoni flow, in view of the problems of uneven film thickness, component separation, and large grain size differences in the process of preparing perovskite thin films caused by Marangoni flow.

[0006] To achieve the above purpose, the present application is realized by the following technical solutions: The present application designs a double-tool-head coating device for preparing uniform perovskite thin films, which includes the following structural arrangements: A substrate platform for placing the substrate to be coated; ​A dual-blade assembly having a degree of freedom to move horizontally relative to the substrate platform (i.e., having a degree of freedom to move horizontally relative to the substrate to be coated), the dual-blade assembly being used to form a uniform perovskite thin film on the substrate. And a drive mechanism connected to the dual-blade assembly for driving the dual-blade assembly to move horizontally relative to the substrate platform (substrate); The dual-blade assembly includes the following structural configuration: A first cutting head, connected to the drive mechanism, is used to coat a perovskite precursor solution onto the surface of the substrate to form a liquid film. And a second cutting head, which is connected to the drive mechanism and disposed downstream of the first cutting head, the second cutting head moves synchronously with the first cutting head, and the second cutting head is used to apply mechanical shearing action to the liquid film formed by the coating of the first cutting head; The gap between the first cutting head and the surface of the substrate is H1, and the gap between the second cutting head and the surface of the substrate is H2, and H1 > H2 is always satisfied. The distance between the first and second cutting heads is L (in mm), and the concentration of the perovskite precursor solution is ρ (in mol / L), which satisfies 10 ≤ L × ρ ≤ 30.

[0007] Specifically, the dual-blade coating device for preparing uniform perovskite thin films designed in this invention is a shear flow field generation and control device based on pure mechanical action. Through the preset micron-level gap between the second blade and the substrate, it directly induces a high-intensity and high-stability vertical velocity gradient (i.e., shear flow field) inside the moving liquid film. This flow field can effectively promote the convective mixing of the liquid film in the thickness direction and quickly homogenize the local concentration differences caused by solvent evaporation, thereby suppressing the Marangoni effect from a physical source. Compared with the existing pneumatic surface shearing, this method of mechanical intervention of the second blade into the liquid film body is more direct, has higher energy transfer efficiency, and completely avoids the negative effects that airflow may bring.

[0008] Furthermore, a dual-blade coating apparatus for preparing uniform perovskite thin films includes a fixing structure on the substrate platform for fixing the substrate to ensure the stability of the substrate position when coating the perovskite precursor solution.

[0009] Furthermore, a dual-blade coating apparatus for preparing uniform perovskite thin films: the fixing structure consists of a plurality of vacuum adsorption holes disposed on the substrate platform for adsorbing and fixing the substrate to the surface of the substrate platform.

[0010] Specifically, the vacuum adsorption hole can be arranged on one surface of the substrate platform and communicate with the inside of the substrate platform. The inside of the substrate platform can be vacuumized by a vacuum pump, so that the vacuum adsorption hole can adsorb and fix the substrate on the surface of the substrate platform, and the substrate can be fixed.

[0011] Further, a double-knife-head coating device for preparing a uniform perovskite thin film is provided. The first knife head is arranged as a slit extrusion coating head, and the gap H1 between the first knife head and the substrate surface can be adjusted.

[0012] Further, a double-knife-head coating device for preparing a uniform perovskite thin film is provided. The second knife head is arranged as a flexible blade, and the gap H2 between the second knife head and the substrate surface can be adjusted, and satisfies 10 μm≤H2≤100 μm.

[0013] Further, a double-knife-head coating device for preparing a uniform perovskite thin film is provided. The gap H2 between the second knife head and the substrate surface satisfies 20 μm≤H2≤50 μm.

[0014] Further, a double-knife-head coating device for preparing a uniform perovskite thin film is provided. The driving mechanism drives the horizontal moving speed of the double-knife-head assembly to be 1-100 mm / s.

[0015] Further, a double-knife-head coating device for preparing a uniform perovskite thin film is provided. The distance L between the first knife head and the second knife head satisfies 1.0 mm≤L≤20.0 mm.

[0016] Further, a double-knife-head coating device for preparing a uniform perovskite thin film is provided. The first knife head and the second knife head are connected to the same rigid connecting frame, the rigid connecting frame is connected to the driving mechanism and is driven to move horizontally by the driving mechanism, so that the second knife head and the first knife head move synchronously.

[0017] The application also provides a method for preparing a uniform perovskite thin film, which adopts the double-knife-head coating device. S1, providing a substrate to be coated with a perovskite precursor solution; S2, placing the substrate on the substrate platform and fixing the substrate by the substrate platform; S3, driving the double-knife-head assembly to move horizontally relative to the substrate by the driving mechanism, and coating the perovskite precursor solution on the surface of the substrate by the first knife head to form a liquid film; the synchronously moving second knife head applies mechanical shearing to the just-formed liquid film after moving a distance L, so as to inhibit the Marangoni flow of the solution and obtain a uniform wet film. S4, heat treating the uniform wet film to crystallize and form a uniform perovskite thin film.

[0018] The above method is also applicable to other fields of doctor-blade film preparation.

[0019] The beneficial effects of the present application are: The double-blade coating device for preparing a uniform perovskite thin film designed by the present application is a double-blade frame with separate front and rear parts and coordinated functions, which realizes the decoupling and integration of the two functions of "precise quantitative coating" and "fluid regulation" in space. The first blade is a coating blade: responsible for the initial supply and thickness of the perovskite precursor solution, forming an initial liquid film with a target thickness; and the second blade is a shear regulation blade, which is located downstream of the first blade, and its core function is to regulate the fluid behavior by applying a restrictive shear force field to the liquid film flowing below, rather than participating in the main coating. The structural design of the double-blade coating device allows the two processes to be optimized simultaneously and accurately (such as the gap and moving speed of the first blade, the gap and inclination angle of the second blade), which widens the process window and provides unprecedented regulation dimensions and flexibility.

[0020] The double-blade coating device for preparing a uniform perovskite thin film designed by the present application replaces the compressed gas, purification, pressure stabilization and gas supply system necessary in the traditional pneumatic shear scheme with a full solid mechanical structure design, bringing multiple advantages, such as: ① system simplification: eliminating the gas system, reducing equipment complexity and manufacturing cost; ② control precision: the gap and inclination angle of the blade can be controlled, which is more accurate and stable than pressure regulation, reducing a key process fluctuation source; ③ enhanced robustness: the process is no longer sensitive to environmental air pressure and gas flow stability, improving consistency and repeatability in large-scale production; ④ environmentally friendly: no gas consumption and no potential solvent environmental pollution problems caused by exhaust.

[0021] The double-blade coating device designed by the present application can also be used for the preparation of a passivation layer in a perovskite solar cell, that is, using the same device to coat a passivation layer solution on the prepared perovskite thin film. Since the amount of passivation layer solution is small, the gap H1 and H2 of the first and second blades can be adjusted, and the shearing action of the second blade ensures the uniform distribution of the passivation layer molecules, avoiding local over-thickness or absence, thereby improving the open-circuit voltage and stability of the perovskite device. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0023] Figure 1 Front view of the double-knife coater designed for the preparation of uniform perovskite thin films for Example 1 of the present application; Figure 2 Schematic view of the solution coating by the first knife and the liquid film shearing treatment by the second knife in the double-knife coater of Example 1; Figure 3 Macrograph of the perovskite thin film prepared for Comparative Example 1; Figure 4 Macrograph of the perovskite thin film prepared for Example 2.

[0024] The reference signs in the figures are as follows: 1 - substrate platform, 2 - double-knife assembly, 3 - substrate, 4 - rigid connection bracket, 21 - first knife, 22 - second knife. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0026] In the description of the present application, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom", etc. indicate the orientation or positional relationship, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" can be explicitly or implicitly included one or more of the features. Moreover, the terms "first", "second", etc. are used to distinguish similar objects, and do not necessarily be used to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0027] Example 1

[0028] As Figure 1As shown, the present embodiment 1 designs a double-knife head coating device for preparing uniform perovskite thin films, which comprises the following structural arrangement: a substrate platform 1 for placing the substrate 3 to be coated, one surface of the substrate platform 1 is further provided with a plurality of vacuum suction holes for suction fixing the substrate 3 to the surface of the substrate platform 1 to ensure the position of the substrate 3 stable when coating the perovskite precursor solution; a double-knife head assembly 2 having the freedom of horizontal movement relative to the substrate platform 1, which is used to form a uniform perovskite thin film on the substrate 3; and a driving mechanism connected with a rigid connecting frame 4, the double-knife head assembly 2 is connected to the rigid connecting frame 4 for driving the double-knife head assembly 2 to move horizontally relative to the substrate 3; wherein the double-knife head assembly 2 comprises the following structural arrangement: a first knife head 21 arranged as a slit extrusion type coating head connected to the rigid connecting frame 4, which is used to coat the perovskite precursor solution on the surface of the substrate 3 to form a liquid film, the gap between the first knife head 21 and the surface of the substrate 3 is H1 (the preferred gap H1 can be adjusted), gap H1 = 100 μm; and a second knife head 22 arranged as a precise flexible doctor blade connected to the rigid connecting frame 4 and arranged downstream of the first knife head 21, the rigid connecting frame 4 is driven to move horizontally by the driving mechanism, thereby driving the second knife head 22 to move synchronously with the first knife head 21, the second knife head 22 is used to apply mechanical shearing action to the liquid film formed by the first knife head 21, the gap between the second knife head 22 and the surface of the substrate 3 is H2 (the preferred gap H1 can be adjusted), gap H2 = 35 μm, the gaps H1 and H2 always satisfy H1 > H2; the driving mechanism drives the horizontal movement speed of the double-knife head assembly 2 to be 30.0 mm / s; the distance between the first knife head 21 and the second knife head 22 is L (L = 10 mm), the concentration of the perovskite precursor solution is ρ (ρ = 1.5 mol / L); In the above embodiment 1, the first knife head 21 is used to coat the perovskite precursor solution on the substrate 3 to form a liquid film; the second knife head 22 is arranged downstream of the first knife head 21 along the coating direction; the first knife head 21 and the second knife head 22 are configured to be driven to move synchronously by the driving mechanism; the gap H2 between the second knife head 22 and the surface of the substrate 3 is arranged to be smaller than the working gap H1 between the first knife head 21 and the surface of the substrate 3, so that during synchronous movement, the second knife head 22 can apply mechanical shearing action to the liquid film just formed by the first knife head 21.

[0029] Example 2

[0030] This embodiment 2 provides a method for preparing a uniform perovskite thin film, which uses the dual-blade coating apparatus of embodiment 1. The method includes the following steps: S1. A substrate 3 is provided for coating the perovskite precursor solution. Specifically, the substrate 3 is an ITO glass substrate 3 pre-deposited with NiOx (wherein ITO forms a transparent conductive layer on the glass substrate, and NiOx is deposited on the transparent conductive layer to form a hole transport layer). S2. Place the substrate 3 on the substrate platform 1 and activate vacuum adsorption to adsorb and fix the substrate 3 to the surface of the substrate platform 1 through the vacuum adsorption holes provided on the substrate platform 1. S3. The driving mechanism drives the dual-blade assembly 2 to move horizontally relative to the substrate 3. The first blade 21 in the dual-blade assembly 2 is used to coat the surface of the substrate 3 with a perovskite precursor solution to form a liquid film. The coating speed is 30 mm / s for the first and second blades 21 and 22 and the temperature of the substrate 3 is 25°C. The perovskite precursor solution was prepared by adding CsI, MABr, and PbB2. FAI, Pb Prepare a 1.5M solution by dissolving the precursor in a mixed solvent according to stoichiometric ratio. The precursor has the chemical formula C. (M F Pb( B The mixed solvent is DMF:DMSO = 9:1; The second cutting head 22, which moves synchronously, applies mechanical shearing to the newly formed liquid film after moving a distance L (10 mm), inhibiting the Marangoni flow of the solution to obtain a uniform wet film. S4. The uniform wet film is heat-treated at 135°C for 15 minutes to crystallize and form a uniform perovskite film.

[0031] The double-knife-head coating device in the above embodiment 2 is started, the first and second knife heads 21, 22 move at a set speed (30 mm / s); the synchronously moving double-knife-head assembly 2 starts to work: the first knife head 21 first coats the perovskite precursor solution to form a liquid film; after about 0.33 seconds (10 mm / 30 mm / s≈0.33 s), the second knife head 22 shears the liquid film which has not yet started to have serious Marangoni flow with a gap of 35 μm; after the coating is completed, the substrate 3 is immediately transferred to a vacuum chamber, and is treated at a vacuum degree of 5.0 Pa for 16 seconds to quickly remove most of the solvent; the wet film is transferred to a heat treatment procedure (135℃, 15 minutes) to complete perovskite film crystallization; the whole treatment process is continuous and synchronous, and the liquid film is seamlessly connected from formation to shearing and homogenization, greatly improving the timeliness and effect of film uniformity control.

[0032] Comparative Example 1

[0033] The perovskite precursor solution is coated on the substrate 3 by using a conventional single-knife head, and after the coating is completed, the substrate 3 is immediately transferred to a vacuum chamber, and is treated at a vacuum degree of 5.0 Pa for 16 seconds to quickly remove most of the solvent; then the wet film is transferred to a heat treatment procedure (135℃, 15 minutes) to complete perovskite film crystallization; the difference between Comparative Example 1 and Embodiment 2 is that the second knife head 22 does not shear the liquid film which has not yet started to have serious Marangoni flow in Comparative Example 1, and the rest of the conditions are the same as in Embodiment 2.

[0034] Test: The perovskite films prepared in the above Embodiment 2 and Comparative Example 1 are compared and analyzed in multiple indexes, and the specific results are as follows: ① Macro appearance: the perovskite film prepared in Comparative Example 1 has visible rainbow stripes and the phenomenon of thick edges and thin center, and the macrograph of the film is as shown in Figure 3 It can be seen that a "coffee ring" caused by Marangoni flow is formed at the edge of the film, causing the problem of uneven film thickness; while the perovskite film prepared in Embodiment 2 is uniform and consistent in film layer, and the surface is smooth without visible defects, and the macrograph of the film is as shown in Figure 4 It is shown that the macroscopic non-uniformity phenomenon of the film caused by Marangoni effect is eliminated when the perovskite film is prepared by using the double-knife-head coating device of the application.

[0035] ② SEM microscopic morphology: the perovskite film prepared in Comparative Example 1 has uneven grain size, a large number of small grains, pores and white Pb clusters, while the perovskite film prepared in Embodiment 2 has large and uniform grain size, and is dense in arrangement without pores and Pb The residual indicates that the double-head coating device of the application can inhibit component separation, promote uniform nucleation and crystallization, and obtain high-quality perovskite films.

[0036] ③Film thickness uniformity: The average thickness of the perovskite film prepared in Comparative Example 1 was 520 nm, and the standard deviation was ± 45 nm; the average thickness of the perovskite film prepared in Example 2 was 515 nm, and the standard deviation was ± 15 nm; it can be seen that the film thickness uniformity of the application is improved by 200%, which indicates that the application greatly improves the film thickness distribution, which is beneficial to the preparation of uniform perovskite films.

[0037] ④PL Mapping: The fluorescence intensity of the perovskite film prepared in Comparative Example 1 is weak and unevenly distributed, and there are a large number of dark spots (defect quenching centers); the fluorescence intensity of the perovskite film prepared in Example 2 is strong and highly uniform, and the number of dark spots is very small, which indicates that the application significantly reduces the defect density of the film, which is beneficial to the carrier transport and collection.

[0038] ⑤Device efficiency (PCE): The lowest efficiency of the perovskite device prepared in Comparative Example 1 is about 16.0%, the best efficiency is about 20.1%, and the average efficiency is 18.05%; the efficiency distribution range is relatively wide (16.0-21.0%); the lowest efficiency of the perovskite device prepared in Example 2 is about 21.2%, the best efficiency is about 22.4%, and the average efficiency is 21.8%; the efficiency distribution range is relatively narrow (21.2-22.4%); it can be seen that the average efficiency of the perovskite device prepared by the application is improved by about 20.8% compared with Comparative Example 1, and the efficiency distribution is highly concentrated, which indicates that the process repeatability and yield of the application are very high.

[0039] ⑥Fill factor (FF): The average fill factor of the perovskite device prepared in Comparative Example 1 is 72%, and the average fill factor of the perovskite device prepared in Example 2 is 80%, which is 11% higher than that of Comparative Example 1, which directly proves that the uniformity of the perovskite film of the application is improved, which reduces the series resistance.

[0040] In summary, the above comparative data fully prove that under the premise of all external conditions being consistent, by using the double-head synchronous coating device and method of the application, through the immediate mechanical shearing action introduced by the second knife head 22, the Marangoni effect can be effectively inhibited, and the uniformity problem of large-area coating is fundamentally solved. The application finally brings significant and consistent improvement in perovskite film quality (morphology, crystallization, component), macroscopic performance (thickness, defects), and final device indicators (efficiency, FF, yield), and has great industrial application potential.

[0041] The above are only used for explaining the present application, and are not intended to limit the present application. Any obvious changes or modifications derived from the technical solutions of the present application are still within the protection scope of the present application.

Claims

1. A double-knife coater for preparing a uniform perovskite thin film, characterized by, The coating device comprises the following structural arrangement: a substrate platform (1) for placing a substrate (3) to be coated; a double-knife head assembly (2) having a freedom of horizontal movement relative to the substrate platform (1), the double-knife head assembly (2) being used to form a uniform perovskite film on the substrate (3); and a driving mechanism connected with the double-knife head assembly (2) for driving the double-knife head assembly (2) to move horizontally relative to the substrate platform (1); wherein the double-knife head assembly (2) comprises the following structural arrangement: a first knife head (21) connected to the driving mechanism for coating a perovskite precursor solution on the surface of the substrate (3) to form a liquid film; and a second knife head (22) connected to the driving mechanism and arranged downstream of the first knife head (21), the second knife head (22) moving synchronously with the first knife head (21), the second knife head (22) being used to apply mechanical shearing action to the liquid film formed by the first knife head (21); the gap between the first knife head (21) and the surface of the substrate (3) is H1, the gap between the second knife head (22) and the surface of the substrate (3) is H2, and H1>H2 is satisfied; the distance between the first knife head (21) and the second knife head (22) is L, and the concentration of the perovskite precursor solution is ρ, and 10≤L×ρ≤30 is satisfied.

2. The dual-knife coater for preparing a uniform perovskite thin film according to claim 1, wherein, The substrate platform (1) is further provided with a fixing structure for fixing the substrate (3) to ensure the stability of the position of the substrate (3) during coating of the perovskite precursor solution.

3. The dual-knife coater for preparing a uniform perovskite thin film according to claim 2, wherein The fixing structure is a plurality of vacuum suction holes arranged on the substrate platform (1) for suction fixing the substrate (3) to the surface of the substrate platform (1).

4. The dual-knife coater for preparing a uniform perovskite thin film according to claim 1, wherein, The first knife head (21) is arranged as a slit extrusion type coating head, which can also adjust the gap H1 with the surface of the substrate (3).

5. The dual-knife coater for preparing a uniform perovskite thin film according to claim 1, wherein, The second knife head (22) is arranged as a flexible blade, which can also adjust the gap H2 with the surface of the substrate (3), and 10μm≤H2≤100μm is satisfied.

6. The dual-knife coater for preparing a uniform perovskite thin film according to claim 5, wherein The gap H2 between the second knife head (22) and the surface of the substrate (3) satisfies 20μm≤H2≤50μm.

7. The dual-knife coater for preparing a uniform perovskite thin film according to claim 1, wherein The horizontal movement speed of the double-knife head assembly (2) driven by the driving mechanism is 1-100mm / s.

8. The dual-knife coater for preparing a uniform perovskite thin film according to claim 1, wherein, The distance L between the first knife head (21) and the second knife head (22) satisfies 1.0mm≤L≤20.0mm.

9. The dual-knife coater for preparing a uniform perovskite thin film according to claim 1, wherein, The first knife head (21) and the second knife head (22) are connected to the same rigid connecting frame (4), the rigid connecting frame (4) is connected to the driving mechanism and driven by the driving mechanism to move horizontally, so as to realize synchronous movement of the second knife head (22) and the first knife head (21).

10. A method for preparing a uniform perovskite thin film, characterized by, The double-knife head coating device according to any one of claims 1-9, the method comprising the following steps: S1, providing a substrate (3) to be coated with a perovskite precursor solution; S2, placing the substrate (3) on the substrate platform (1) and fixing it; S3, driving the double-tool head assembly (2) to move horizontally relative to the substrate (3) by using the driving mechanism, and using the first tool head (21) to coat a perovskite precursor solution on the surface of the substrate (3) to form a liquid film; The second tool head (22) moving synchronously applies mechanical shearing to the just-formed liquid film after moving a distance L, inhibits the solution Marangoni flow, and obtains a uniform wet film; S4, performing heat treatment on the uniform wet film to crystallize and form a uniform perovskite thin film.

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