A preparation method for homogenizing perovskite thin film based on standing wave acoustic field processing

Abstract

The application provides a preparation method for homogenizing perovskite thin film based on standing wave acoustic field processing, and relates to the technical field of organic electric solid-state devices. The preparation method for homogenizing perovskite thin film provided by the application comprises the following steps: forming a perovskite wet film on a substrate; and obtaining a perovskite thin film after standing wave acoustic field processing, vacuum flash evaporation and annealing crystallization of the perovskite wet film. The preparation method applies standing wave acoustic field to online homogenization processing of the perovskite wet film, applies the standing wave acoustic field before a large amount of solvent is evaporated and solute starts to gather, the sound wave propagation direction of the standing wave acoustic field is perpendicular to the film surface of the perovskite wet film, solute particles are subjected to transverse acoustic radiation force in the film surface and are rearranged, thereby eliminating thickness fluctuation, coating stripes and other macroscopic non-uniform defects caused by uneven distribution of solute particles, and improving the uniformity of the perovskite thin film and the photoelectric conversion efficiency of a perovskite solar module.

Description

Technical Field

[0001] This application relates to the field of organic solid-state device technology, and in particular to a method for preparing perovskite thin films based on standing wave acoustic field treatment for homogenization. Background Technology

[0002] Perovskite solar cells have attracted much attention due to their high photoelectric conversion efficiency and low manufacturing cost. Slit coating, as a scalable coating technology, has advantages such as uniform film formation, high material utilization, and suitability for roll-to-roll production, and has become an important direction for the industrialization of perovskite solar cells.

[0003] However, the rapid solvent evaporation during slot coating easily leads to problems such as uneven film formation, small grain size, and numerous defects. Those skilled in the art generally believe that the unevenness of the coated film should be addressed through external airflow or vacuum flash evaporation, but they have consistently failed to recognize that the essence of this unevenness lies in the uneven distribution of solute particles. Simultaneously, mechanical vibrations during coating and transfer interfere with the surface tension's smoothing effect on the liquid film and cause oscillations in the solution flow, resulting in unevenness in the film even in the wet film stage immediately after coating. Therefore, existing technologies still lack a method to homogenize the film in the wet film stage, creating the necessary conditions for subsequent vacuum crystallization and annealing to prepare high-quality, uniform films. Summary of the Invention

[0004] In view of this, this application provides a method for homogenizing perovskite thin films based on standing wave acoustic field treatment. The preparation method provided by this application can homogenize perovskite wet films, thereby improving the uniformity of perovskite thin films and the photoelectric conversion efficiency of perovskite solar modules.

[0005] This application provides a method for preparing perovskite thin films based on standing wave acoustic field treatment for homogenization, including the following steps: a) Formation of a perovskite wet film on the substrate; b) After subjecting the perovskite wet film to standing wave acoustic field treatment, vacuum flash evaporation and annealing crystallization, a perovskite thin film is obtained.

[0006] In some specific implementations, in step b), the entire perovskite wet film enters the standing wave acoustic field processing area within 0.1s to 10s after its formation.

[0007] In some specific implementations, the frequency of the standing wave sound field processing is 20kHz~100kHz; The power density of the standing wave acoustic field processing is 0.1 W / cm². 2 ~5W / cm 2 .

[0008] In some specific implementations, the standing wave acoustic field processing time is 1s to 15s.

[0009] In some specific implementations, the apparatus for processing the standing wave acoustic field includes: Ultrasonic transducer array 1; The ultrasonic transducer array 1 includes a mounting plate 2 and a piezoelectric ceramic transducer 3 fixed on the mounting plate 2; The reflector plate 4 is arranged parallel to the ultrasonic transducer array 1; The side of the mounting plate 2 on which the piezoelectric ceramic transducer 3 is fixed faces the reflector plate 4.

[0010] In some specific implementations, the distance between the radiating surface of the piezoelectric ceramic transducer and the reflector is (1 / 2)·kλ, where k is a positive integer and λ is the wavelength corresponding to the frequency of the standing wave acoustic field processing.

[0011] In some specific implementations, the distance between the radiating surface of the piezoelectric ceramic transducer and the reflector is 10mm to 30mm.

[0012] In some specific implementations, the piezoelectric ceramic transducers are arranged in a planar array; The thickness of the piezoelectric ceramic transducer is 25mm~125mm.

[0013] In some specific implementations, the perovskite wet film comprises a perovskite salt and a solvent; The perovskite salt has the atomic ratio of formula (Ⅰ): AMX3 (Ⅰ); A is selected from one or more of formamidine ions, methylamine ions, and cesium ions; M is selected from one or two of lead ions and tin ions; X is a halide ion; The solvent is a mixed solvent, which is selected from at least two of N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.

[0014] In some specific implementations, the thickness of the perovskite wet film is 1 μm to 5 μm; The thickness of the perovskite thin film is 400 nm to 600 nm.

[0015] This application provides a method for homogenizing perovskite thin films based on standing wave acoustic field treatment, comprising the following steps: forming a perovskite wet film on a substrate; subjecting the perovskite wet film to standing wave acoustic field treatment, vacuum flash evaporation, and annealing crystallization to obtain a perovskite thin film. The preparation method provided in this application applies a standing wave acoustic field to the online homogenization treatment of the perovskite wet film, applying the standing wave acoustic field before the solvent evaporates in large quantities and the solute begins to aggregate, ensuring that particle rearrangement is completed before the sol-gel transition. Simultaneously, the perovskite wet film is positioned at the effective potential well location of the standing wave acoustic field (i.e., the location of the maximum acoustic radiation force gradient) to ensure that solute particles receive sufficient migration driving force, thereby eliminating thickness fluctuations, coating streaks, and other macroscopic non-uniform defects caused by uneven solute particle distribution, improving the uniformity of the perovskite thin film and the photoelectric conversion efficiency of the perovskite solar module. Experimental results show that the perovskite thin film treated with a standing wave acoustic field has a larger grain size and no voids, indicating fewer surface defects and higher film quality. Furthermore, the open-circuit voltage (V0) of the perovskite solar module prepared after standing wave acoustic field treatment was significantly improved. OC It can reach 51.36V, with a fill factor (FF) of 0.806 and a photoelectric conversion efficiency (PCE) of 19%. Attached Figure Description

[0016] Figure 1 The standing wave acoustic field device provided in Embodiment 1 of this application includes an ultrasonic transducer array, a mounting plate, a piezoelectric ceramic transducer, and a reflector. Figure 2 This is a schematic diagram of the transfer of the substrate into the standing wave acoustic field processing area in Embodiment 2 of this application, where 1 is an ultrasonic transducer array, 2 is a mounting plate, 3 is a piezoelectric ceramic transducer, 4 is a reflector, 5 is a perovskite wet film, 6 is a substrate, and 7 is a conveyor belt. Figure 3 These are macroscopic morphology images of the perovskite thin films prepared in Example 2 and Comparative Example 1 of this application. Figure 3 Figure a shows the macroscopic morphology of the perovskite film prepared in Comparative Example 1. Figure 3 Image b is a macroscopic morphology diagram of the perovskite thin film prepared in Example 2; Figure 4 These are scanning electron microscope (SEM) images of the perovskite thin films prepared in Example 2 and Comparative Example 1 of this application. Figure 4 Image a is a scanning electron microscope (SEM) image of the perovskite thin film prepared in Comparative Example 1. Figure 4 b is a scanning electron microscope image of the perovskite thin film prepared in Example 2; Figure 5 The current-voltage (IV) curves are for the perovskite solar modules prepared in Example 3 and Comparative Example 2 of this application. Detailed Implementation

[0017] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0018] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0019] It should be understood that the order of steps or the sequence of actions is not important as long as this application remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0020] The use of any and all instances or exemplary language such as “e.g.” or “including” herein is merely intended to better illustrate the application and does not constitute a limitation on the scope of the application unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of this application.

[0021] Furthermore, the numerical ranges and parameters used to define this application are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any numerical value inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise explicitly stated, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately." Here, "approximately" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range.

[0022] This application provides a standing wave acoustic field device, comprising: Ultrasonic transducer array 1; The ultrasonic transducer array 1 includes a mounting plate 2 and a piezoelectric ceramic transducer 3 fixed to one side of the mounting plate 2; The reflector plate 4 is arranged parallel to the ultrasonic transducer array 1; The side of the mounting plate 2 on which the piezoelectric ceramic transducer 3 is fixed faces the reflector plate 4.

[0023] The standing wave acoustic field device provided in this application includes an ultrasonic transducer array 1, which comprises a mounting plate 2 and a piezoelectric ceramic transducer 3 fixed to one side of the mounting plate 2. Its main function is to emit low-frequency ultrasonic waves to form a standing wave acoustic field in the air gap. Through the uniform effect of the acoustic field on the surface of the perovskite wet film, it regulates the solvent evaporation rate and the crystallization process.

[0024] This application does not impose special restrictions on the size of the mounting plate 2 and the number and spacing of the piezoelectric ceramic transducers 3. The size of the mounting plate 2 and the number and spacing of the piezoelectric ceramic transducers 3 can be reasonably adjusted according to actual needs, meaning that the size of the mounting plate 2 matches the number of piezoelectric ceramic transducers 3 and the spacing between adjacent transducers. In some specific implementations, the piezoelectric ceramic transducers 3 are arranged in a planar array. For example, for a processing area of ​​300mm × 300mm (the size of the substrate in this application), the size of the mounting plate 2 is 350mm × 350mm × 10mm (length × width × height), the diameter of the piezoelectric ceramic transducers is 40mm, and a 7×7 planar array is used, with 49 piezoelectric ceramic transducers. The center distance between adjacent transducers is 40mm to 60mm, preferably 50mm, to ensure complete coverage of the substrate area by the sound field. In some specific implementations, the mounting plate 2 is selected from stainless steel or aluminum alloy, preferably stainless steel, with a surface flatness better than ±0.05mm.

[0025] The piezoelectric ceramic transducer 3 described in this application is a sandwich-type composite transducer. Its resonant frequency is adjusted by modifying the material and thickness of the front cover plate, controlling the target frequency range of the standing wave sound field to be 20kHz~100kHz. This application does not impose any special limitations on the thickness of the piezoelectric ceramic transducer 3, as long as it meets the target frequency. In some specific implementations, the thickness of the piezoelectric ceramic transducer 3 is 25mm~125mm.

[0026] In this application, the target wavelength λ and target frequency f in the standing wave sound field have a relationship as expressed in equation (II): λ = c1 / f(Ⅱ); Wherein, λ is the wavelength in air corresponding to the frequency of the standing wave sound field processing, f is the target frequency, and c1 is the speed of sound in air, which is 340m / s.

[0027] In some specific implementations, the frequency of the standing wave sound field is 20kHz to 100kHz, preferably 30kHz to 60kHz, and more preferably 30kHz to 50kHz. For example, when the frequency is 40kHz, the wavelength λ of the sound wave in air is approximately 8.5mm.

[0028] In this application, the power density is controlled by adjusting the input electrical power of the ultrasonic transducer array 1 and the effective radiation area of ​​the ultrasonic transducer array 1, as detailed in equation (Ⅲ): Power density = P × η / A (Ⅲ); Wherein, P is the input electrical power of the ultrasonic transducer array 1, η is the electroacoustic conversion efficiency of the ultrasonic transducer array 1, and A is the effective radiation area of ​​the ultrasonic transducer array 1.

[0029] In practice, the output power of the ultrasonic power supply is adjusted to achieve the target power density of the acoustic field acting on the wet film surface. In some specific implementations, the power density is 0.1 W / cm². 2 ~5W / cm 2 The preferred value is 0.5 W / cm. 2 ~2W / cm 2 More preferably 0.8 W / cm 2 ~1.2W / cm 2 .

[0030] The standing wave acoustic field device provided in this application includes a reflector 4, which is arranged parallel to the ultrasonic transducer array 1.

[0031] This application establishes a relationship between the distance L between the radiating surface of the piezoelectric ceramic transducer 3 fixed to the mounting plate 2 and the reflective plate 4 and the wavelength λ, as given by equation (Ⅳ): L=(1 / 2)·kλ(Ⅳ; Where k is a positive integer, and λ is the wavelength corresponding to the frequency of the standing wave sound field processing.

[0032] In some specific implementations, the distance between the radiating surface of the piezoelectric ceramic transducer 3 fixed to the mounting plate 2 and the reflector 4 is 10mm~30mm, preferably 15mm~25mm, and more preferably 21.25mm. For example, when the frequency is 20kHz, the half-wavelength is approximately 8.6mm, k is 2~3, and the corresponding distance is 10mm~30mm; when the frequency is 100kHz, the half-wavelength is approximately 1.7mm, k is 6~18, and the corresponding distance is 10mm~30mm. In some specific implementations, the size of the reflector 4 is consistent with the size of the mounting plate 2; this application does not have any special limitations. In some specific implementations, the reflector 4 is selected from stainless steel or aluminum alloy, preferably stainless steel, with a surface flatness better than ±0.05mm. In some specific implementations, the size of the reflector 4 is 350mm×350mm×10mm. In some specific implementations, the parallelism between the ultrasonic transducer array 1 and the reflector 4 is better than ±0.1°.

[0033] In some specific implementations, a typical standing wave acoustic field device includes: Ultrasonic transducer array 1; The ultrasonic transducer array 1 includes a mounting plate 2 and a piezoelectric ceramic transducer 3 fixed to one side of the mounting plate 2; The mounting plate 2 measures 350mm × 350mm × 10mm (length × width × height), with a surface flatness better than ±0.05mm. The piezoelectric ceramic transducers 3 are arranged in a 7×7 array and fixed to the mounting plate 2. The diameter of the radiating surface of each piezoelectric ceramic transducer 3 is 40mm, and its thickness is 50mm. There are 49 piezoelectric ceramic transducers 3, with a spacing of 50mm between them. The corresponding acoustic parameters are a frequency of 40kHz, a wavelength of 8.5mm, and a power density of 1W / cm². 2 ; A reflector plate 4 is arranged parallel to the ultrasonic transducer array 1, wherein the side of the piezoelectric ceramic transducer 3 fixed on the mounting plate 2 faces the reflector plate 4; The reflector 4 has dimensions of 350mm × 350mm × 10mm and a surface flatness better than ±0.05mm; The mounting plate 2 and the reflector 4 are selected from stainless steel plates; The distance between the radiating surface of the piezoelectric ceramic transducer 3 and the reflector plate 4 in the ultrasonic transducer array 1 is 21.25 mm.

[0034] This application provides a method for preparing perovskite thin films based on standing wave acoustic field treatment for homogenization, including the following steps: a) Formation of a perovskite wet film on the substrate; b) After subjecting the perovskite wet film to standing wave acoustic field treatment, vacuum flash evaporation and annealing crystallization, a perovskite thin film is obtained.

[0035] This application first forms a perovskite wet film on a substrate. Specifically, a perovskite salt is dissolved in a solvent, stirred to obtain a perovskite precursor solution, and then coated onto the substrate through a slit to form a perovskite wet film.

[0036] The perovskite salt described in this application has the atomic ratio of formula (Ⅰ): AMX3 (Ⅰ); wherein, A includes, but is not limited to, formamidinium ion (FA). + ), Methylamine ion (MA + ) and cesium ions (Cs + The ions A can be one or more of these ions. When A is a variety of ions, this application does not impose any special restrictions on the specific proportions of each ion. In some specific implementations, A is preferably a formamidinium ion (FA). + ) and methylamine ions (MA + M includes, but is not limited to, lead ions (Pb). 2+ ) and tin ions (Sn 2+ The ions M can be one or more of these, and when M is a variety of ions, this application does not impose any special restrictions on the specific proportions of each ion. In some specific implementations, M is preferably lead ion (Pb). 2+ X is a halide ion, which can be an iodide ion (I).- ), bromide ions (Br) - ) and chloride ions (Cl - X can be one or more of these ions, and when X is a variety of ions, this application does not impose any special restrictions on the specific proportions of each ion. In some specific implementations, X is preferably an iodide ion (I... - ) and chloride ions (Cl - ).

[0037] This application controls the proportion of each ion in the perovskite thin film by controlling the molar ratio of A, M, and X. In some specific implementations, the solvent is a mixed solvent selected from at least two of N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, preferably N,N-dimethylformamide and N-methylpyrrolidone. This application does not have any particular limitation on the proportion of the above mixed solvent. In some specific implementations, the volume ratio of N,N-dimethylformamide to N-methylpyrrolidone is 5~9:1, preferably 6~8:1, and more preferably 7:1. In some specific implementations, the perovskite precursor solution is preferably prepared in a nitrogen glove box at a temperature of 22℃±3℃. In some specific implementations, the stirring speed is 600rpm~1000rpm, preferably 700rpm~900rpm, and the stirring time is 2h~6h, preferably 3h~5h. In some specific implementations, it is preferred to filter the solution after stirring and then use it for later use.

[0038] After obtaining the perovskite precursor solution, a perovskite wet film is formed on the substrate through slit coating. This application does not impose any particular limitation on the injection volume of the slit coating; it can be reasonably adjusted according to the size of the substrate and the desired wet film thickness. In some specific implementations, the substrate is an ITO glass substrate or an FTO glass substrate, preferably an FTO glass substrate. In some specific implementations, the thickness of the substrate is 1.6 mm to 3.2 mm, preferably 2 mm to 2.5 mm, and more preferably 2.2 mm. In some specific implementations, when the substrate size is 300 mm × 300 mm and the wet film thickness is 3 μm, the injection volume of the slit coating is 12.8 μl / s. In some specific implementations, the coating speed of the slit coating is 40 mm / s to 60 mm / s, preferably 45 mm / s to 55 mm / s. In some specific implementations, the height of the slit coating tip from the substrate is 70μm to 100μm, preferably 80μm to 90μm. In some specific implementations, the thickness of the wet film is 1μm to 5μm, preferably 2μm to 4μm.

[0039] After obtaining the perovskite wet film, the perovskite wet film is subjected to standing wave acoustic field treatment, vacuum flash evaporation and annealing crystallization to obtain a perovskite thin film.

[0040] The standing wave acoustic field processing described in this application is achieved by applying a standing wave acoustic field to the perovskite wet film using the standing wave acoustic field device described above. The standing wave processing device and related parameter settings are as described above and will not be repeated here. Specifically, the standing wave acoustic field processing procedure is described in [link to relevant documentation]. Figure 2 After the formation of the perovskite wet film and before solvent evaporation and solute aggregation, the substrate 6 forming the perovskite wet film 5 is carried by a conveyor belt 7 and passes through the standing wave acoustic field region at a constant speed between the ultrasonic transducer array 1 and the reflector plate 4. During the passage, the perovskite wet film is continuously subjected to the standing wave acoustic field, ensuring that the perovskite wet film is uniformly subjected to the standing wave acoustic field and avoiding the formation of new non-uniformities due to the acoustic wave coverage blind zone caused by the gaps in the transducer array. At the same time, the perovskite wet film is located at the effective potential well position of the standing wave acoustic field (i.e., the position with the maximum acoustic radiation force gradient) to ensure that the solute particles are subjected to sufficient migration driving force. Furthermore, by controlling the frequency, power density, and action time of the standing wave acoustic field, the solute particles in the wet film migrate and rearrange under the action of acoustic radiation force, thereby eliminating thickness fluctuations, coating streaks, and other macroscopic non-uniform defects caused by uneven distribution of solute particles.

[0041] The parameter settings for frequency, wavelength, and power density of the standing wave acoustic field described in this application are as described above and will not be repeated here. In some specific implementations, the number of piezoelectric ceramic transducers 3, the size of the mounting plate 2, and the size of the reflector 4 are determined according to the coating width, and this application has no special limitations. In some specific implementations, the entire perovskite wet film region enters the standing wave acoustic field processing region within 0.1s to 10s after the perovskite wet film is formed, preferably within 4s to 8s. In some specific implementations, the surface of the perovskite wet film is located at the effective potential well position in the standing wave acoustic field. In some specific implementations, the velocity of the substrate is 10mm / s to 100mm / s, preferably 40mm / s to 60mm / s, and more preferably 50mm / s. In some specific implementations, the standing wave sound field processing time is 1s~15s, preferably 8s~15s, and more preferably 11s~13s; the standing wave sound field processing time is the total time from the front end of the substrate entering the standing wave sound field to the rear end of the substrate leaving the standing wave sound field.

[0042] After treatment with a standing wave acoustic field, a perovskite thin film is obtained through vacuum flash evaporation and annealing crystallization. In some specific implementations, the vacuum flash evaporation process is preferably carried out at a vacuum level of 0.1 Pa for 40 s, and maintained at a vacuum level of 0.1 Pa for 20 s. In some specific implementations, the annealing temperature is 100℃~150℃, preferably 120℃~140℃, and the time is 10 min~50 min, preferably 20 min~40 min. In some specific implementations, the thickness of the perovskite thin film is 400 nm~600 nm, preferably 500 nm~600 nm, and more preferably 550 nm.

[0043] This application also provides a perovskite thin film, which is prepared by the perovskite thin film preparation method described in the above technical solution.

[0044] This application also provides a method for preparing a perovskite solar module, comprising the following steps: A hole transport layer is formed on the substrate surface; A perovskite wet film is formed on the surface of the hole transport layer, and the perovskite wet film is subjected to standing field acoustic wave treatment, vacuum flash evaporation and annealing crystallization to obtain a perovskite thin film. An electron transport layer is formed on the surface of the perovskite thin film; A back electrode layer is formed on the surface of the electron transport layer.

[0045] Specifically, it includes the following steps: Pretreatment of the substrate; A hole transport layer is formed on the substrate surface.

[0046] This application first pre-treats the substrate, which includes cleaning and plasma treatment. Cleaning removes oil and impurities from the substrate surface, while plasma treatment improves the substrate's surface energy and wettability. In some specific implementations, the substrate is an indium tin oxide (ITO) glass substrate or a fluorine-doped tin oxide (FTO) glass substrate, preferably an FTO glass substrate. In some specific implementations, the cleaning process preferably involves sequential ultrasonic cleaning with deionized water and ethanol. In some specific implementations, the ultrasonic cleaning time with deionized water and anhydrous ethanol is independently 5 min to 20 min, preferably 5 min to 15 min.

[0047] After pretreatment of the substrate, a hole transport layer is formed on the substrate surface. This application does not impose any particular limitation on the preparation method of the hole transport layer. In some specific implementations, the hole transport layer can be prepared by magnetron sputtering, spin coating, or slot coating, etc. The material of the hole transport layer includes one or more of nickel oxide, [2-(9,9-dimethyl-9H-fluoren-2-yl)ethyl]phosphonic acid, (4-(3,6-dimethoxy-9H-carbazole-9-yl)butylphosphonic acid), (4-(9H-carbazole-9-yl)butylphosphonic acid), and (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid.

[0048] This application preferably employs magnetron sputtering to form a hole transport layer on the substrate surface. Specifically, FTO is placed in the magnetron sputtering chamber of a magnetron sputtering apparatus to perform magnetron sputtering on the target material, thereby forming the hole transport layer. In some specific implementations, the working gas pressure of the magnetron sputtering chamber is 0.5 Pa to 1.5 Pa, preferably 0.7 Pa to 1 Pa. In some specific implementations, the target material is preferably a nickel target. In some specific implementations, the substrate holder is preferably controlled to advance at a fixed speed to ensure in-plane uniformity of the film thickness. In some specific implementations, the thickness of the hole transport layer is 5 nm to 30 nm, preferably 10 nm to 20 nm.

[0049] After forming a hole transport layer on the substrate surface, a perovskite wet film is formed on the surface of the hole transport layer. The perovskite wet film is then subjected to standing field acoustic wave treatment, vacuum flash evaporation, and annealing crystallization to obtain a perovskite thin film.

[0050] The preparation of the perovskite thin film is as described above, and will not be repeated here.

[0051] After obtaining the perovskite thin film, an electron transport layer is formed on the surface of the perovskite thin film. This application does not impose any particular limitation on the preparation method of the electron transport layer. In some specific implementations, the electron transport layer can be prepared by vacuum evaporation, atomic layer deposition, or spin coating, etc., and the material of the electron transport layer includes fullerene C. 60 SnO2, TiO2, [6,6]-phenyl-C 61 - Isomethyl butyrate and [6,6]-phenyl-C 71 One or more of isomethyl butyrate.

[0052] This application preferably employs vacuum evaporation and atomic layer deposition to form the electron transport layer. Specifically, this application uses vacuum evaporation to form the main electron transport layer on the substrate surface, and then uses atomic layer deposition to form a dense barrier layer on the surface of the main electron transport layer, thus obtaining a complete electron transport layer. In some specific implementations, the vacuum degree of the vacuum evaporation is preferably ≤5×10⁻⁶. -4Pa. In some specific implementations, the evaporation rate is 0.1 Å / s to 0.5 Å / s, preferably 0.1 Å / s to 0.3 Å / s. In some specific implementations, the material of the main electron transport layer is preferably C. 60 The thickness is 5nm~50nm, preferably 10nm~30nm. In some specific implementations, the substrate temperature is preferably kept below 50℃ during the vapor deposition process to avoid thermal damage to the perovskite film. A main electron transport layer is obtained, and then an atomic layer deposition process is used to form a dense barrier layer on the surface of the main electron transport layer, resulting in a complete electron transport layer. The atomic layer deposition process ensures the density and conformal coverage of the film, effectively blocking water vapor and ion migration. In some specific implementations, the deposition temperature of the dense barrier layer is 80℃~110℃, preferably 90℃~110℃; the number of cycles is 100~200 times, preferably 130~140 times. In some specific implementations, the material of the dense barrier layer is preferably SnO2, and the thickness is 5nm~25nm, preferably 10nm~20nm.

[0053] After obtaining the electron transport layer, a back electrode layer is formed on the surface of the electron transport layer. This application does not impose any particular limitation on the preparation method of the back electrode layer. In some specific implementations, the back electrode layer can be prepared by vacuum evaporation or electron beam evaporation deposition, and the back electrode layer is selected from a metal back electrode, a carbon-based back electrode, or a transparent bottom electrode.

[0054] This application preferably employs a vacuum evaporation method to form the back electrode layer on the surface of the electron transport layer. In some specific implementations, the vacuum level of the vacuum chamber is preferably ≤5×10⁻⁶. -4 Pa. In some specific implementations, the evaporation rate of Cu is 1 Å / s to 10 Å / s, preferably 4 Å / s to 6 Å / s. In some specific implementations, the material of the back electrode layer is preferably Cu, and the thickness is 100 nm to 150 nm, preferably 110 nm to 130 nm.

[0055] Furthermore, during the fabrication of perovskite solar modules, laser scribing (P1, P2, P3) is also required to achieve series interconnection of sub-cells. This application does not impose any special restrictions on the laser scribing process.

[0056] In some specific implementations, the P1 laser scribing specifically includes the following steps: P1 Laser Scribing: After the substrate pretreatment is completed, a nanosecond laser is preferably used to etch the conductive layer of the substrate. The laser wavelength is 532nm, the etching linewidth is controlled at 30μm, and the etching depth must completely remove the conductive layer of the substrate to form mutually insulated sub-cell units. After etching, the substrate is dried with nitrogen gas.

[0057] In some specific implementations, the P2 laser scribing includes the following steps: P2 laser scribing: After P1 laser scribing, hole transport layer, perovskite thin film, and electron transport layer are completed, P2 laser scribing is performed. A laser is used to etch the perovskite thin film and electron transport layer at a wavelength of 532 nm and an etching linewidth of 30 μm. The etching depth must completely remove the perovskite layer to the interface of the substrate conductive layer / hole transport layer to achieve series connection between sub-cells.

[0058] In some specific implementations, the P3 laser scribing includes the following steps: P3 laser scribing: After P1 scribing, hole transport layer, perovskite thin film, electron transport layer, P2 laser scribing, and back electrode layer are completed sequentially, P3 laser scribing is performed. A laser is used to etch the back electrode layer, electron transport layer, perovskite thin film, and hole transport layer. The laser wavelength is 532nm, and the etching linewidth is 50μm, achieving series isolation between adjacent sub-cells and completing the series-parallel structure of the module.

[0059] This application also provides a perovskite solar module, which is prepared by the perovskite solar module preparation method described in the above technical solution.

[0060] A typical structure of the perovskite solar module described in this application includes: Base; A hole transport layer formed on the surface of the substrate; A perovskite thin film formed on the surface of the hole transport layer; An electron transport layer is formed on the surface of the perovskite thin film; A back electrode layer is formed on the surface of the electron transport layer.

[0061] The perovskite solar module includes a substrate. The substrate is used to collect and transport photogenerated carriers, while also providing mechanical support for the device. The fabrication of the substrate has been described above and will not be repeated here.

[0062] The perovskite solar module includes a hole transport layer. This layer efficiently transports holes to the electrodes while simultaneously blocking electrons from moving to the outer electrodes, thus achieving carrier separation. The fabrication of the hole transport layer has been described above and will not be repeated here.

[0063] The perovskite solar module includes a perovskite thin film. The perovskite thin film is the core component of the perovskite solar module, used to absorb sunlight and excite electrons and holes. The preparation of the perovskite thin film has been described above and will not be repeated here.

[0064] The perovskite solar module includes an electron transport layer. This layer efficiently transports electrons to the electrodes and blocks holes from moving to the outer electrodes, thus separating charge carriers and preventing direct contact between the perovskite layer and the electrodes, which could lead to internal short circuits. The fabrication of the electron transport layer has been described above and will not be repeated here.

[0065] The perovskite solar module includes a back electrode layer. The back electrode layer is used to collect photogenerated carriers and guide them to an external circuit. The fabrication of the back electrode layer has been described above and will not be repeated here.

[0066] This application also provides a perovskite optoelectronic device, comprising a perovskite thin film prepared by the perovskite thin film preparation method described in the above technical solution or the perovskite thin film described in the above technical solution.

[0067] This application provides a method for homogenizing perovskite thin films based on standing wave acoustic field treatment, comprising the following steps: forming a perovskite wet film on a substrate; subjecting the perovskite wet film to standing wave acoustic field treatment, vacuum flash evaporation, and annealing crystallization to obtain a perovskite thin film. The preparation method provided in this application applies a standing wave acoustic field to the online homogenization treatment of the perovskite wet film, applying the standing wave acoustic field before the solvent evaporates in large quantities and the solute begins to aggregate, ensuring that particle rearrangement is completed before the sol-gel transition. Simultaneously, the perovskite wet film is positioned at the effective potential well location of the standing wave acoustic field (i.e., the location of the maximum acoustic radiation force gradient) to ensure that solute particles receive sufficient migration driving force, thereby eliminating thickness fluctuations, coating streaks, and other macroscopic non-uniform defects caused by uneven solute particle distribution, improving the uniformity of the perovskite thin film and the photoelectric conversion efficiency of the perovskite solar module. Experimental results show that the perovskite thin film treated with a standing wave acoustic field has a larger grain size and no voids, indicating fewer surface defects and higher film quality. Furthermore, the open-circuit voltage (V0) of the perovskite solar module prepared after standing wave acoustic field treatment was significantly improved. OC It can reach 51.36V, with a fill factor (FF) of 0.806 and a photoelectric conversion efficiency (PCE) of 19%.

[0068] The present invention is further illustrated below with reference to the embodiments. The scope of protection of the present invention is not limited to the following embodiments.

[0069] Example 1

[0070] The standing wave acoustic field device provided in this application is referred to [reference needed]. Figure 1 , Figure 1 The standing wave acoustic field device provided in Embodiment 1 of this application includes: 1 is an ultrasonic transducer array, 2 is a mounting plate, 3 is a piezoelectric ceramic transducer, and 4 is a reflector. Specifically, it includes: Ultrasonic transducer array 1; The ultrasonic transducer array 1 includes a mounting plate 2 and a piezoelectric ceramic transducer 3 fixed to one side of the mounting plate 2; The mounting plate 2 has dimensions of 350mm × 350mm × 10mm (length × width × height) and a surface flatness better than ±0.05mm; the piezoelectric ceramic transducers 3 are arranged in a 7×7 array and fixed to the mounting plate 2, the diameter of the radiating surface of the piezoelectric ceramic transducer 3 is 40mm and the thickness is 50mm; the number of piezoelectric ceramic transducers 3 is 49, and the spacing between the piezoelectric ceramic transducers 3 is 50mm; A reflector plate 4 is arranged parallel to the ultrasonic transducer array 1, wherein the side of the piezoelectric ceramic transducer 3 fixed on the mounting plate 2 faces the reflector plate 4; The reflector 4 has dimensions of 350mm × 350mm × 10mm and a surface flatness better than ±0.05mm; The mounting plate 2 and the reflector 4 are selected from stainless steel plates; The distance between the radiating surface of the piezoelectric ceramic transducer 3 and the reflector plate 4 in the ultrasonic transducer array 1 is 21.25 mm.

[0071] Example 2

[0072] (1) Preparation of perovskite precursor solution: In a nitrogen glove box, 1.47 mol / L lead iodide (PbI2), 1.4 mol / L formamidinium iodide (FAI), and 0.14 mol / L methylamine hydrochloride (MACl) were dissolved in a mixed solvent of N,N-dimethylformamide and N-methylpyrrolidone in a stoichiometric ratio of 7:1 to prepare a perovskite precursor solution with FAPbI3 as the perovskite component. The glove box temperature was 22±3℃. The prepared solution was placed on a stirring table and stirred at 800 rpm for 4 hours. After stirring, the solution was filtered and then coated onto a substrate.

[0073] (2) Substrate: The substrate is FTO glass with a thickness of 2.2mm and a size of 300mm×300mm.

[0074] (3) Coating process: The coating is slit coating, the liquid injection volume is 12.8 μl / s, the coating speed is 50 mm / s, the distance between the blade and the substrate is 85 μm, and the wet film thickness is about 3 μm, thus obtaining a wet film.

[0075] (4) Standing wave acoustic field treatment: After coating is completed, such as Figure 2As shown, the wet film is conveyed through the standing wave acoustic field region described in Example 1 at a uniform speed of 50 mm / s via a conveyor belt. First, it is ensured that the entire wet film region enters the standing wave acoustic field processing region within 0.1s to 10s after the wet film is formed. Second, the standing wave acoustic field processing time of the wet film (the total time from the front end of the substrate entering the acoustic field to the rear end of the substrate leaving the acoustic field) is approximately 12s.

[0076] The parameters for the above standing wave sound field processing are: frequency 40kHz, power density 1W / cm². 2 The wavelength of the sound wave is 8.5 mm.

[0077] (5) Vacuum flash evaporation: The film after standing wave acoustic field treatment is placed in the vacuum flash evaporation chamber, the target vacuum degree is set to 0.1 Pa, the pumping time is 40 s, and it is maintained at 0.1 Pa vacuum degree for 20 s.

[0078] (6) Annealing and crystallization treatment: The wet film after vacuum flash evaporation (VCD) is placed on a heating stage at 130°C and heated for 30 minutes to obtain a perovskite film with a thickness of 550 nm.

[0079] Example 3

[0080] The fabrication process of perovskite solar modules is as follows: (1) Cleaning the substrate: 300mm×300mm FTO glass with a thickness of 2.2mm was ultrasonically cleaned for 10min each with deionized water and ethanol, and then the FTO glass was subjected to plasma cleaning treatment.

[0081] (2) P1 laser etching: A nanosecond laser is used to etch the FTO conductive layer. The laser wavelength is 532nm, the etching linewidth is controlled at 30μm, and the etching depth is required to completely remove the FTO layer to form mutually insulated sub-cell units. Nitrogen gas is used to dry the cells after etching.

[0082] (3) Place the FTO in the magnetron sputtering chamber, using a nickel oxide ceramic target. Adjust the chamber to the set working pressure of 0.8 Pa, turn on the backplate heating, and control the substrate holder to advance at a fixed speed to ensure the in-plane uniformity of the film thickness. Finally, obtain NiO with a thickness of about 15 nm. x film.

[0083] (4) Perovskite deposition: The perovskite precursor solution was coated onto NiO using a slot coating method. xOn an FTO substrate, the injection rate was 12.8 μL / s, the coating speed was 50 mm / s, the nozzle height was 85 μm, and the wet film thickness was approximately 3 μm. After coating, a standing wave acoustic field treatment was performed (the parameters and conditions of the treatment process were the same as in Example 2), followed by vacuum flash evaporation (target vacuum degree 0.1 Pa, evacuation for 40 s, holding for 20 s), and finally annealing on a 130°C heating stage for 30 min to obtain a perovskite light-absorbing layer with a thickness of 550 nm.

[0084] (5) Electron transport layer C 60 Deposition: The annealed perovskite film is transferred to a thermal evaporation apparatus, and deposition is carried out under a vacuum of less than 5 × 10⁻⁶. -4 C was deposited at an evaporation rate of 0.2 Å / s under Pa conditions. 60 Thin film, with a thickness controlled at 20 nm. The substrate temperature is kept below 50°C during the evaporation process to avoid thermal damage to the perovskite layer.

[0085] (6) Barrier layer ALD deposition: Atomic layer deposition (ALD) technology was used on C 60 A dense barrier layer of SnO2 is deposited on the surface of the film. The precursors are tetra(dimethylamino)tin (TDMASn) and deionized water. The deposition temperature is 100℃, the cycle count is 150 times, and the film thickness is approximately 15nm. The ALD process ensures the density and conformal coverage of the film, effectively blocking water vapor and ion migration.

[0086] (7) P2 laser scribing: The perovskite layer, electron transport layer and barrier layer are etched using a laser with a wavelength of 532 nm and an etching linewidth of 30 μm. The etching depth is required to completely remove the perovskite layer down to FTO / NiO. x The interface enables series connection between sub-batteries.

[0087] (8) Cu electrode deposition: Cu back electrode is deposited using vacuum evaporation method, with a vacuum degree of less than 5×10 -4 Pa, evaporation rate 5 Å / s, film thickness 120 nm.

[0088] (9) P3 laser scribing: A laser is used to scribing the Cu electrode, barrier layer, electron transport layer, perovskite layer and NiO. x The layers are etched using a laser wavelength of 532nm and an etching linewidth of 50μm to achieve series isolation between adjacent sub-cells and complete the series-parallel structure of the module.

[0089] Comparative Example 1

[0090] The only difference from Example 2 is that standing wave acoustic field processing is not performed.

[0091] Comparative Example 2

[0092] The only difference from Example 3 is that standing wave acoustic field processing is not performed.

[0093] Experimental Example 1

[0094] The perovskite films prepared in Example 2 and Comparative Example 1 were compared. Figure 3 These are macroscopic morphology images of the perovskite thin films prepared in Example 2 and Comparative Example 1 of this application, wherein... Figure 3 Figure a shows the macroscopic morphology of the perovskite film prepared in Comparative Example 1. Figure 3 Image b shows the macroscopic morphology of the perovskite film prepared in Example 2. Figure 3 It can be seen that the surface is more uniform after being subjected to the standing wave sound field, with no obvious black and white stripes or grooves.

[0095] Figure 4 These are scanning electron microscope (SEM) images of the perovskite thin films prepared in Example 2 and Comparative Example 1 of this application, wherein... Figure 4 Image a is a scanning electron microscope (SEM) image of the perovskite thin film prepared in Comparative Example 1. Figure 4 Image b is a scanning electron microscope (SEM) image of the perovskite thin film prepared in Example 2. Figure 4 It can be seen that after being subjected to the standing wave acoustic field, the grain size is larger and there are no voids, indicating fewer surface defects and higher film quality.

[0096] Experimental Example 2

[0097] The perovskite solar modules prepared in Example 3 and Comparative Example 2 were subjected to IV testing. The tests were conducted under standard test conditions (AM 1.5G, 100mW / cm²). 2 At 25°C, the current-voltage (IV) characteristics of the component were tested using a solar simulator and a source meter. Before testing, light intensity calibration was performed. During testing, the probe contacted the Cu electrode and the edge of the FTO. The scanning voltage range was 0V to 60V, the scanning rate was 1V / s, and the open-circuit voltage (V) was recorded. OC ), short-circuit current (I) SC ), fill factor (FF) and photoelectric conversion efficiency (PCE) parameters.

[0098] See results Figure 5 , Figure 5 The current-voltage (IV) curves are for the perovskite solar modules prepared in Example 3 and Comparative Example 2 of this application. Figure 5 The V of the battery device is obtained OC I SC PCE and FF, the results are shown in Table 1. As can be seen from Table 1, the perovskite solar modules prepared after standing wave acoustic field treatment have a higher open-circuit voltage (V). OC ), fill factor (FF) and photoelectric conversion efficiency (PCE).

[0099] Table 1. V values ​​of perovskite solar modules in Example 3 and Comparative Example 2 OC I SC , PCE and FF

[0100] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and inventive concept of this application, should be included within the scope of protection of this application.

Claims

1. A method for preparing perovskite thin films based on standing wave acoustic field treatment for homogenization, characterized in that, Includes the following steps: a) Formation of a perovskite wet film on the substrate; b) After subjecting the perovskite wet film to standing wave acoustic field treatment, vacuum flash evaporation and annealing crystallization, a perovskite thin film is obtained; A standing wave acoustic field is applied before the solvent evaporates in large quantities and the solute begins to aggregate, and particle rearrangement is ensured before the sol-gel transition; at the same time, the perovskite wet film is positioned at the effective potential well location of the standing wave acoustic field, which is the location where the acoustic radiation force gradient is maximum. In step b), the entire perovskite wet film enters the standing wave acoustic field treatment area within 0.1s to 10s after its formation. The standing wave acoustic field processing time is 1s to 15s, which is the total time from when the front end of the substrate enters the standing wave acoustic field to when the rear end of the substrate leaves the standing wave acoustic field.

2. The preparation method according to claim 1, characterized in that, The frequency of the standing wave acoustic field processing is 20kHz~100kHz; The power density of the standing wave acoustic field processing is 0.1 W / cm². 2 ~5W / cm 2 .

3. The preparation method according to claim 1, characterized in that, The device for processing standing wave acoustic fields includes: Ultrasonic transducer array; The ultrasonic transducer array includes a mounting plate and piezoelectric ceramic transducers fixed on the mounting plate; A reflector plate arranged parallel to the ultrasonic transducer array; The side of the mounting plate on which the piezoelectric ceramic transducer is fixed faces the reflector.

4. The preparation method according to claim 3, characterized in that, The distance between the radiating surface of the piezoelectric ceramic transducer and the reflector is (1 / 2)·kλ, where k is a positive integer and λ is the wavelength corresponding to the frequency of the standing wave acoustic field processing.

5. The preparation method according to claim 4, characterized in that, The distance between the radiating surface of the piezoelectric ceramic transducer and the reflector is 10mm~30mm.

6. The preparation method according to claim 3, characterized in that, The piezoelectric ceramic transducers are arranged in a planar array; The thickness of the piezoelectric ceramic transducer is 25mm~125mm.

7. The preparation method according to claim 1, characterized in that, The perovskite wet film comprises perovskite salt and solvent; The perovskite salt has the atomic ratio of formula (Ⅰ): AMX3 (Ⅰ); A is selected from one or more of formamidine ions, methylamine ions, and cesium ions; M is selected from one or two of lead ions and tin ions; X is a halide ion; The solvent is a mixed solvent, which is selected from at least two of N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.

8. The preparation method according to claim 1, characterized in that, The thickness of the perovskite wet film is 1 μm to 5 μm; The thickness of the perovskite thin film is 400 nm to 600 nm.

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