A method and device for ultrasonic-assisted preparation of perovskite thin film, and perovskite solar cell

Abstract

The application provides a method and device for ultrasonic-assisted preparation of a perovskite film and a perovskite solar cell. The perovskite film is obtained by placing a wet film in a container, vacuumizing the container, applying ultrasonic to the wet film, then keeping pressure, and finally supplementing gas into the container to normal pressure. The film forming regulation method is realized by ultrasonic induction of the internal micro flow field of the wet film, enhancement of solvent-solute exchange and improvement of solute distribution uniformity, and is combined with a vacuum flash drying process, so that the nucleation behavior of the perovskite film and the intermediate phase evolution process are significantly improved, and the crystallization quality is finally improved. Further, the nanomaterial is added into the precursor solution, the crystallization kinetics of the perovskite is effectively regulated through the synergistic effect of the ultrasonic micro flow field and the nanomaterial, the grain growth is more uniform and more oriented, the holes and defects in the film are significantly reduced, and the overall microstructure is optimized, so that a high-quality structure foundation is provided for a high-performance optoelectronic device.

Description

Technical Field

[0001] This invention relates to the field of perovskite thin film preparation technology, and in particular to a method and apparatus for ultrasound-assisted preparation of perovskite thin films and perovskite solar cells. Background Technology

[0002] Perovskite thin films, as the core functional layer of optoelectronic devices such as photovoltaic devices and photodetectors, directly determine the photoelectric conversion efficiency, stability, and repeatability of the devices through their film formation quality. Vacuum flash evaporation (VCD) is widely used in the laboratory preparation of perovskite thin films because it can rapidly accelerate solvent removal, induce the formation of perovskite mesophase, and promote crystallization. However, this process has the following problems in small-area and large-area film formation: In the initial stage of vacuuming, the solvent on the surface of the wet film is rapidly evaporated due to the sudden drop in vapor pressure, leading to solute concentration accumulation near the upper interface and the potential preferential precipitation of non-uniform crystal nuclei, making the film prone to surface roughness; The precursor solution has inherent velocity and thickness gradients along the flow direction on the substrate surface, resulting in inconsistent solvent evaporation rates and differences in liquid film thickness distribution. This leads to significant spatial differences in the subsequent crystallization process, resulting in non-uniformity in film thickness and grain distribution.

[0003] Given the current shortcomings of vacuum flash evaporation (VCD) in the preparation of perovskite thin films, it is necessary to improve upon this method. Summary of the Invention

[0004] To address the aforementioned technical deficiencies, this invention provides a method and apparatus for ultrasound-assisted preparation of perovskite thin films, and a perovskite solar cell. This invention utilizes an ultrasound-induced microfluidic field within the liquid film, enhancing solvent-solute exchange and improving solute distribution uniformity to control film formation. Combined with a vacuum flash drying process, this significantly improves the nucleation behavior and mesophase evolution of perovskite thin films, ultimately enhancing crystallization quality.

[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 ultrasound-assisted preparation of perovskite thin films, comprising the following steps:

[0007] Prepare perovskite precursor solution;

[0008] The perovskite precursor solution is coated onto the substrate surface to form a wet film;

[0009] The wet film is placed in a container, and the container is evacuated to bring the pressure inside the container to the first pressure. While evacuating, the wet film is ultrasonically treated. Then, pressure holding treatment is performed under the first pressure. Finally, gas is added to the container to bring it to atmospheric pressure and maintained for a period of time to obtain a perovskite thin film.

[0010] Preferably, the container is evacuated to bring the pressure inside the container to a first pressure within 3 to 4 seconds, where the first pressure is 6 to 10 Pa.

[0011] Preferably, the container is evacuated to bring the pressure inside the container to the first pressure, and the wet film is subjected to ultrasonic treatment. The process parameters controlled by the ultrasonic treatment are: ultrasonic frequency of 40~50KHz, ultrasonic power of 5~10W, and ultrasonic time of 10~15s.

[0012] Preferably, a pressure holding process is performed under the first pressure for 20-25 seconds.

[0013] In the step of replenishing the container with gas, the gas includes at least one of dry nitrogen, dry air, and dry carbon dioxide;

[0014] Finally, gas is added to the container to atmospheric pressure and maintained for 15-30 seconds to obtain a perovskite thin film.

[0015] Preferably, after adding gas to the container to atmospheric pressure and maintaining it for a period of time, the wet film is removed and subjected to heat treatment to obtain a perovskite thin film.

[0016] The heat treatment temperature is 80~150℃ and the time is 10~20min.

[0017] Preferably, the perovskite precursor solution includes a solvent, a precursor, and nanomaterials;

[0018] The precursors include ammonium thiocyanate, stannous fluoride, cesium iodide, methylamine iodide, formamidinium iodide, stannous iodide, and lead iodide.

[0019] Preferably, the solvent includes N,N-dimethylformamide and dimethyl sulfoxide;

[0020] The nanomaterials include at least one of the following: metal oxide nanoparticles, sulfide quantum dots, selenide quantum dots, two-dimensional materials, carbon nanomaterials, metal nanoparticles, polymer nanoparticles, and metal-organic framework materials.

[0021] The metal oxide nanoparticles include at least one of NiO2, ZnO, TiO2, SnO2, Al2O3, ZrO2, and HfO2;

[0022] The sulfide quantum dots include at least one of PbS and CdS;

[0023] The selenide quantum dots include at least one of PbSe and CdSe;

[0024] The two-dimensional material includes at least one of graphene, graphene oxide, MXene, and h-BN;

[0025] The carbon nanomaterials include at least one of CNTs and carbon quantum dots;

[0026] The metal nanoparticles include at least one of Ag nanoparticles, Au nanoparticles, Ni nanoparticles, and Cu nanoparticles;

[0027] The polymer nanoparticles include PMMA nanoparticles and PS nanospheres;

[0028] The mass ratio of ammonium thiocyanate, stannous fluoride, cesium iodide, methylamine iodide, formamidinium iodide, stannous iodide, and lead iodide is (1~2):(12~15):(40~50):(80~90):(180~190):(330~340):(410~420);

[0029] The volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is (2.5~3.5):1;

[0030] The mass-to-volume ratio of ammonium thiocyanate to N,N-dimethylformamide is (1~2)g:(700~800)mL;

[0031] The mass fraction of nanomaterials in the perovskite precursor solution is 0.05~0.15%.

[0032] Secondly, the present invention also provides an application of the perovskite thin film prepared by the method in the preparation of perovskite solar cells.

[0033] Thirdly, the present invention also provides a perovskite solar cell, comprising the perovskite thin film prepared by the method.

[0034] Fourthly, the present invention also provides an apparatus for the method of ultrasound-assisted preparation of perovskite thin films, comprising:

[0035] A container, the interior of which is hollow to accommodate a wet film, and the container is provided with a vacuum port for connecting an external vacuum device to evacuate the container.

[0036] An ultrasonic generator, located outside the container, is used to ultrasonically treat the wet film.

[0037] The ultrasonic-assisted method for preparing perovskite thin films of the present invention, along with its preparation method and applications, has the following advantages compared to existing technologies:

[0038] The present invention discloses a method for ultrasonic-assisted preparation of perovskite thin films. A wet film is placed in a container, and the container is evacuated to a pressure of a first pressure. While evacuating the container, ultrasonic treatment is applied to the wet film on the substrate surface. Then, a pressure holding treatment is performed under the first pressure. Finally, gas is added to the container to atmospheric pressure and maintained for a period of time to obtain the perovskite thin film. By using an ultrasonic-induced microfluidic field within the wet film to enhance solvent-solute exchange and improve solute distribution uniformity, combined with a vacuum flash drying process, the nucleation behavior and intermediate phase evolution of the perovskite thin film are significantly improved, ultimately enhancing crystallization quality. Furthermore, nanomaterials are added to the precursor solution. Through the synergistic effect of the ultrasonic microfluidic field and the nanomaterials, the crystallization kinetics of the perovskite are effectively controlled, resulting in more uniform and oriented grain growth. This significantly reduces pores and defects within the film, optimizes the overall microstructure, and provides a high-quality structural foundation for high-performance optoelectronic devices. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the process for ultrasound-assisted preparation of perovskite thin films according to the present invention;

[0041] Figure 2 This is a schematic diagram of the device for ultrasonic-assisted preparation of perovskite thin films according to the present invention.

[0042] Figure 3 This is a scanning electron microscope image of the perovskite thin film prepared in Example 1;

[0043] Figure 4 The image shows a scanning electron microscope (SEM) image of the perovskite thin film prepared in Comparative Example 1.

[0044] Figure 5 The image shows a scanning electron microscope (SEM) image of the perovskite thin film prepared in Comparative Example 2.

[0045] Figure 6 JV curve of the perovskite solar cell prepared from the perovskite thin film in Comparative Example 2;

[0046] Figure 7 The JV curve is shown for the perovskite solar cell prepared from the perovskite thin film in Example 1. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0048] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0049] This application provides a method for ultrasound-assisted preparation of perovskite thin films, comprising the following steps:

[0050] S1. Prepare perovskite precursor solution;

[0051] S2. Coat the perovskite precursor solution onto the substrate surface to form a wet film;

[0052] S3. Place the wet film in a container, evacuate the container to make the pressure inside the container the first pressure, and sonicate the wet film while evacuating the vacuum. Then, perform pressure holding treatment under the first pressure. Finally, add gas to the container to the normal pressure and maintain it for a period of time to obtain a perovskite thin film.

[0053] This invention aims to solve the technical problems existing in the traditional vacuum flash evaporation (VCD) process for perovskite thin film preparation, such as uneven solvent evaporation, solute enrichment on the liquid film surface, concentration gradient along the coating direction, uneven drying of the liquid film caused by non-uniform pressure in the cavity, and asynchronous crystal nucleation. Specifically, this invention places the wet film in a container, evacuates the container to a first pressure, and simultaneously applies ultrasonic treatment to the wet film on the substrate surface while evacuating the container. Then, pressure holding treatment is performed under the first pressure. Finally, gas is added to the container to atmospheric pressure (101.325 kPa) and maintained for a period of time to obtain a perovskite thin film. By using an ultrasonic-induced microfluidic field inside the wet film, enhancing solvent-solute exchange and improving the uniformity of solute distribution, and combining it with the vacuum flash drying process, the nucleation behavior and mesophase evolution process of the perovskite thin film are significantly improved, ultimately improving the crystallization quality.

[0054] This invention involves placing a wet film in a container and first evacuating it to a certain pressure. While evacuating the container, ultrasonic treatment is applied to the wet film on the substrate surface. The ultrasound transmits high-frequency vibrations into the interior of the wet film, generating a microfluidic field that redistributes the solute, solvent, and nanoparticles, suppressing local concentration gradients caused by rapid solvent evaporation at the interface. Microscale turbulent flow is formed inside the wet film, promoting solvent transport to the interface and making the evaporation rate more uniform in different areas of the liquid film. During the VCD process, the ultrasound is used to homogenize the wet film, suppressing large-area non-uniform drying problems caused by pressure gradients in the coating direction or inside the cavity. In the final annealing stage (i.e., heat treatment), more synchronized nucleation and grain growth are achieved, thereby obtaining a dense, uniform, and low-defect perovskite thin film.

[0055] In some embodiments, a vacuum is drawn inside the container to bring the pressure inside the container to a first pressure within 3 to 4 seconds, and the first pressure is 6 to 10 Pa.

[0056] In some embodiments, a vacuum is drawn inside the container to bring the internal pressure to a first pressure, while the wet film is simultaneously subjected to ultrasonic treatment. The process parameters for ultrasonic treatment are: ultrasonic frequency of 40~50KHz, ultrasonic power of 5~10W, and ultrasonic time of 10~15s. Specifically, a vacuum is drawn inside the container to bring the internal pressure to the first pressure, and the ultrasonic time is t1 (3~4s). Then, a pressure holding treatment is performed under the first pressure, and ultrasonic treatment continues during this time, with the ultrasonic time being t2. t1 + t2 is 10~15s.

[0057] In some embodiments, a pressure holding process is performed under the first pressure for 20-25 seconds.

[0058] In the step of replenishing the container with gas, the gas includes at least one of dry nitrogen, dry air, and dry carbon dioxide; by replenishing the container with dry gas to adjust the solvent evaporation rate of the liquid film, the quality of the perovskite thin film is further optimized.

[0059] In some embodiments, gas is finally added to the container to atmospheric pressure and maintained for 15-30 seconds to obtain a perovskite thin film.

[0060] In some embodiments, after adding gas to the container to atmospheric pressure and maintaining it for a period of time, the wet film is removed and subjected to heat treatment to obtain a perovskite thin film.

[0061] The heat treatment temperature is 80~150℃ and the time is 10~20min.

[0062] Heat treatment enables more synchronized nucleation and grain growth, resulting in dense, uniform perovskite films with low defects.

[0063] In some embodiments, the perovskite precursor solution includes a solvent, a precursor, and nanomaterials;

[0064] Precursors include ammonium thiocyanate (NH4SCN), stannous fluoride (SnF2), cesium iodide (CsI), methylamine iodide (MAI, CH3NH3I), formamidinium iodide (FAI, CH5IN2), stannous iodide (SnI2), and lead iodide (PbI2).

[0065] In some embodiments, the solvent includes N,N-dimethylformamide and dimethyl sulfoxide;

[0066] Nanomaterials include at least one of the following: metal oxide nanoparticles, sulfide quantum dots, selenide quantum dots, two-dimensional materials, carbon nanomaterials, metal nanoparticles, polymer nanoparticles, and metal-organic framework materials.

[0067] Metal oxide nanoparticles include at least one of NiO2, ZnO, TiO2, SnO2, Al2O3, ZrO2, and HfO2;

[0068] Sulfide quantum dots include at least one of PbS and CdS;

[0069] Selenide quantum dots include at least one of PbSe and CdSe;

[0070] Two-dimensional materials include at least one of graphene, graphene oxide, MXene, and h-BN;

[0071] Carbon nanomaterials include at least one of CNTs and carbon quantum dots;

[0072] Metal nanoparticles include at least one of Ag nanoparticles, Au nanoparticles, Ni nanoparticles, and Cu nanoparticles;

[0073] Polymer nanoparticles include PMMA nanoparticles and PS nanospheres;

[0074] The mass ratio of ammonium thiocyanate, stannous fluoride, cesium iodide, methylamine iodide, formamidinium iodide, stannous iodide, and lead iodide is (1~2):(12~15):(40~50):(80~90):(180~190):(330~340):(410~420);

[0075] The volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is (2.5~3.5):1;

[0076] The mass-to-volume ratio of ammonium thiocyanate to N,N-dimethylformamide is (1~2) g:(700~800) mL;

[0077] The mass fraction of nanomaterials in the perovskite precursor solution is 0.05~0.15%.

[0078] In some embodiments, the perovskite precursor solution is coated onto the substrate surface by spin coating. Specifically, the spin coating parameters are: rotation speed of 500~6000 r / min and spin coating time of 20~60s.

[0079] In some embodiments, the perovskite precursor liquid is coated onto the substrate surface using a slot coating method. Specifically, the coating process parameters are: coating speed 5~20mm / s, slot-to-substrate distance 50~150μm, and coating ambient temperature 20~30℃.

[0080] In some embodiments, the perovskite precursor solution is coated onto the substrate surface by a scraping method. Specifically, the scraping process parameters are: scraper moving speed 10~30mm / s, and scraper angle with substrate 30°~60°.

[0081] In some embodiments, the substrate is a rigid substrate or a flexible substrate; the rigid substrate is one of glass / ITO, glass / FTO, and silicon wafer substrate; the flexible substrate is one of PEN, PET, and PI flexible polymer substrate.

[0082] Further, refer to Figure 1The diagram illustrates the process of ultrasound-assisted perovskite thin film preparation according to the present invention. A perovskite precursor solution is spin-coated onto a substrate to form a uniform wet precursor film. The spin-coated wet film is then placed into a container, and a vacuum is applied to bring the container pressure to a first pressure. Simultaneously with the vacuum, the wet film on the substrate surface is subjected to ultrasonic treatment. A pressure holding process is then performed at the first pressure. Finally, gas is added to the container to atmospheric pressure and maintained for a period of time to obtain the perovskite thin film. Vacuuming allows the solvent to evaporate rapidly, inducing rapid crystallization of the perovskite precursor. Ultrasound is generated by an ultrasonic generator at the bottom of the container and transmitted to the wet film via solid-state coupling, forming a microfluidic field within the liquid film. This eliminates concentration gradients, promotes uniform dispersion of nanoparticles (such as SiO2), and achieves uniform drying throughout the entire surface. The vacuum-flash-evaporated film is then heat-treated to complete the perovskite crystallization process, forming a highly crystalline and dense perovskite thin film, providing a high-quality light-absorbing layer for subsequent device fabrication.

[0083] Based on the same inventive concept, the present invention also provides an application of the perovskite thin film prepared by the method in the preparation of perovskite solar cells.

[0084] Based on the same inventive concept, the present invention also provides a perovskite solar cell, comprising a perovskite thin film prepared by the above method.

[0085] Specifically, the perovskite solar cell of the present invention comprises: a substrate layer, a hole transport layer, a perovskite light-absorbing layer, an interface modification layer, a double-layer electron transport layer (specifically including a first electron transport layer and a second electron transport layer), a hole-blocking layer, and a metal electrode; wherein, the perovskite light-absorbing layer is the perovskite thin film prepared in this invention (specifically, a perovskite thin film is prepared on the surface of the hole transport layer according to the method of this invention), with a thickness of 300~900nm; wherein, the substrate layer is ITO (indium tin oxide), with a thickness of 180~220nm; the hole transport layer is PEDOT:PSS (i.e., poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid)), with a thickness of 20~40nm; the interface modification layer is EDADI (ethylenediamine diiodide), with a thickness of 5~10nm; the first electron transport layer is PCBM (i.e., [6,6]-phenyl- The first electron transport layer is C61-methyl butyrate, with a thickness of 40-60 nm; the second electron transport layer is C60 (fullerene), with a thickness of 30-50 nm; the hole blocking layer is BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), with a thickness of 5-8 nm; and the metal electrode is Ag (silver), with a thickness of 80-120 nm.

[0086] Based on the same inventive concept, the present invention also provides an apparatus for the above-described method of ultrasound-assisted preparation of perovskite thin films, comprising:

[0087] Container 1 is hollow inside to accommodate the wet film. Container 1 is provided with a vacuum port 10 for connecting an external vacuum device to evacuate the container.

[0088] An ultrasonic generator 2, located outside the container 1, is used to ultrasonically treat the wet film.

[0089] For details, please refer to Figure 2 As shown, a perovskite precursor solution is coated onto the surface of a substrate 3 to form a wet film 30. The substrate 3 with the wet film 30 is placed in a container 1. An ultrasonic generator 2 is located outside the container 1 and at its bottom. The ultrasonic generator 2 is attached to the bottom wall of the container 1. The container 1 is equipped with a vacuum port 10 for connecting to a vacuum device (such as a vacuum pump). During use, the container is first evacuated to a first pressure. While evacuating the container, the ultrasonic generator 2 is activated to generate ultrasonic waves. The ultrasonic waves penetrate the bottom wall of the container and the substrate to enter the interior of the wet film. The ultrasonic waves generate a microfluidic field in the wet film, causing the solute, solvent, and nanoparticles to redistribute, suppressing the local concentration gradient caused by the rapid evaporation of the interfacial solvent, thereby improving the nucleation behavior and intermediate phase evolution process of the perovskite film, and ultimately improving the crystallization quality. Then, a pressure holding treatment is performed under the first pressure. Finally, gas is added to the container to bring it to atmospheric pressure and maintained for a period of time. After heat treatment, the perovskite film is obtained.

[0090] The following further illustrates the method for ultrasonic-assisted preparation of perovskite thin films and perovskite solar cells according to specific embodiments. This section further describes the content of the present invention in conjunction with specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0091] Example 1

[0092] This embodiment provides a method for ultrasound-assisted preparation of perovskite thin films, including:

[0093] S1. Preparation of perovskite precursor solution, specifically including:

[0094] 1.5 g NH4SCN, 14.1 g SnF2, 46.77 g CsI, 85.84 g MAI, 185.73 g FAI, 335.26 g SnI2, and 414.91 g PbI2 were added to 750 mL of N,N-dimethylformamide (DMF) and 250 mL of dimethyl sulfoxide (DMSO). The mixture was stirred at 300 rpm for 20 min. Then, nano-SiO2 (average particle size of 50 nm) was added, and the mixture was stirred for another 10 min to obtain the perovskite precursor solution. The mass fraction of nano-SiO2 in the perovskite precursor solution was 0.1%.

[0095] S2. The perovskite precursor solution was coated onto the surface of the substrate (the substrate is an ITO substrate) by spin coating. The spin coating parameters were: rotation speed: 2000 r / min, spin coating time: 60s.

[0096] S3. Place the wet film in a container and evacuate the container to a pressure of 6 Pa within 4 seconds. While evacuating, sonicate the wet film. Then, maintain the pressure at 6 Pa for 20 seconds. Finally, add dry nitrogen to the container to bring it to atmospheric pressure and maintain it for 20 seconds. Remove the wet film and perform heat treatment to obtain a perovskite thin film. The process parameters controlled by the ultrasonic treatment are: ultrasonic frequency of 40 kHz, ultrasonic power of 5 W, and ultrasonic time of 10 seconds (i.e., ultrasonic time of 4 seconds during vacuuming and 6 seconds of ultrasonication during the pressure maintenance at 6 Pa).

[0097] The heat treatment temperature was 150℃ and the time was 15 minutes.

[0098] Example 2

[0099] This embodiment provides a method for ultrasound-assisted preparation of perovskite thin films, including:

[0100] S1. Prepare the perovskite precursor solution, as in Example 1;

[0101] S2. The perovskite precursor liquid is coated onto the surface of the substrate (the substrate is an ITO substrate) using a slit coating method. Specifically, the coating process parameters are: coating speed 10 mm / s, slit spacing 100 μm between the slit and the substrate, and coating ambient temperature 25℃.

[0102] S3. Place the wet film in a container and evacuate the container to a pressure of 6 Pa within 4 seconds. While evacuating, sonicate the wet film. Then, maintain the pressure at 6 Pa for 20 seconds. Finally, add dry nitrogen to the container to bring it to atmospheric pressure and maintain it for 20 seconds. Remove the wet film and perform heat treatment to obtain a perovskite thin film. The process parameters controlled by the ultrasonic treatment are: ultrasonic frequency of 40 kHz, ultrasonic power of 5 W, and ultrasonic time of 10 seconds (i.e., ultrasonic time of 4 seconds during vacuuming and 6 seconds of ultrasonication during the pressure maintenance at 6 Pa).

[0103] The heat treatment temperature was 100℃ and the time was 20 minutes.

[0104] Example 3

[0105] This embodiment provides a method for ultrasound-assisted preparation of perovskite thin films, including:

[0106] S1. Prepare the perovskite precursor solution, as in Example 1;

[0107] S2. The perovskite precursor solution is coated onto the surface of the substrate (the substrate is an ITO substrate) using a scraping method. The scraping process parameters are: scraper moving speed 20mm / s, and the angle between the scraper and the substrate 30°.

[0108] S3. Place the wet film in a container and evacuate the container to a pressure of 6 Pa within 4 seconds. While evacuating, sonicate the wet film. Then, maintain the pressure at 6 Pa for 20 seconds. Finally, add dry nitrogen to the container to bring it to atmospheric pressure and maintain it for 20 seconds. Remove the wet film and perform heat treatment to obtain a perovskite thin film. The process parameters controlled by the ultrasonic treatment are: ultrasonic frequency of 40 kHz, ultrasonic power of 5 W, and ultrasonic time of 10 seconds (i.e., ultrasonic time of 4 seconds during vacuuming and 6 seconds of ultrasonication during the pressure maintenance at 6 Pa).

[0109] The heat treatment temperature was 120℃ and the time was 15 minutes.

[0110] Comparative Example 1

[0111] This comparative example provides a method for preparing a perovskite thin film, comprising:

[0112] S1. Preparation of perovskite precursor solution, specifically including:

[0113] 1.5 g NH4SCN, 14.1 g SnF2, 46.77 g CsI, 85.84 g MAI, 185.73 g FAI, 335.26 g SnI2, and 414.91 g PbI2 were added to 750 mL of N,N-dimethylformamide (DMF) and 250 mL of dimethyl sulfoxide (DMSO) and stirred at 300 r / min for 20 min to obtain a perovskite precursor solution.

[0114] S2. The perovskite precursor solution was coated onto the surface of the substrate (the substrate is an ITO substrate) by spin coating. The spin coating parameters were: rotation speed: 2000 r / min, spin coating time: 60s.

[0115] S3. Place the wet film in a container, evacuate the container to make the pressure in the container 6Pa within 4s, then maintain the pressure at 6Pa for 20s, finally add dry nitrogen to the container to normal pressure and maintain it for 20s, take out the wet film, and perform heat treatment to obtain a perovskite thin film.

[0116] The heat treatment temperature was 150℃ and the time was 15 minutes.

[0117] Comparative Example 2

[0118] This comparative example provides a method for preparing a perovskite thin film, comprising:

[0119] S1. Preparation of perovskite precursor solution, specifically including:

[0120] 1.5 g NH4SCN, 14.1 g SnF2, 46.77 g CsI, 85.84 g MAI, 185.73 g FAI, 335.26 g SnI2, and 414.91 g PbI2 were added to 750 mL of N,N-dimethylformamide (DMF) and 250 mL of dimethyl sulfoxide (DMSO). The mixture was stirred at 300 rpm for 20 min. Then, nano-SiO2 (average particle size of 50 nm) was added, and the mixture was stirred for another 10 min to obtain the perovskite precursor solution. The mass fraction of nano-SiO2 in the perovskite precursor solution was 0.1%.

[0121] S2. The perovskite precursor solution was coated onto the surface of the substrate (the substrate is an ITO substrate) by spin coating. The spin coating parameters were: rotation speed: 2000 r / min, spin coating time: 60s.

[0122] S3. Place the wet film in a container, evacuate the container to make the pressure in the container 6Pa within 4s, then maintain the pressure at 6Pa for 20s, finally add dry nitrogen to the container to normal pressure and maintain it for 20s, take out the wet film, and perform heat treatment to obtain a perovskite thin film.

[0123] The heat treatment temperature was 150℃ and the time was 15 minutes.

[0124] Performance Characterization

[0125] Figure 3 The image shows a scanning electron microscope (SEM) image of the perovskite thin film (Ultrasonic+VCD(PVK+SiO2), ultrasonic-assisted vacuum flash evaporation + perovskite + SiO2) prepared in Example 1 (the top image is the surface SEM image of the perovskite thin film, and the bottom image is the corresponding cross-sectional SEM image).

[0126] Figure 4The image shows a scanning electron microscope (SEM) image of the perovskite film (VCD(PVK), vacuum flash evaporation + perovskite) prepared in Comparative Example 1 (the top image is the SEM image of the perovskite film surface, and the bottom image is the corresponding cross-sectional SEM image).

[0127] Figure 5 The image shows a scanning electron microscope (SEM) image of the perovskite film (VCD(PVK+SiO2), vacuum flash evaporation + perovskite + SiO2) prepared in Comparative Example 2 (the top image is the SEM image of the perovskite film surface, and the bottom image is the corresponding cross-sectional SEM image).

[0128] Depend on Figure 4 The SEM images of the mid-surface show that the perovskite film prepared in Comparative Example 1 has an uneven grain size distribution, with obvious mixing of fine and large grains. Micropores and cracks are visible at the grain boundaries, resulting in a high surface roughness. Figure 4 The mid-section morphology shows that the perovskite film prepared in Comparative Example 1 has a disordered grain arrangement, with equiaxed or tilted growth, a large number of gaps and pores, an uneven interface with the substrate, and obvious contact defects.

[0129] Depend on Figure 5 The mid-surface SEM images show that the perovskite film prepared in Comparative Example 2 has an overall increased grain size and relatively uniform distribution, but local agglomeration and grain boundary cracking still exist. While the introduction of SiO2 nanoparticles improved some of the nucleation behavior, it did not completely eliminate the defects. Figure 5 The mid-section morphology shows that the grain arrangement of the perovskite film prepared in Comparative Example 2 has been improved, but there are still local looseness and uneven interfaces, and the growth of columnar crystals is discontinuous.

[0130] Depend on Figure 3 The SEM images of the mid-surface show that the perovskite film prepared in Example 1 has highly uniform grain size, clear grain boundaries without obvious cracks, and a smooth and dense surface without obvious agglomeration or pores, exhibiting optimal surface quality; Figure 3 The mid-section morphology shows that the perovskite film prepared in Example 1 forms continuous columnar crystals perpendicular to the substrate, with clear grain boundaries, no obvious pores inside, and smooth contact with the substrate and upper interface, resulting in significantly improved structural density.

[0131] In summary, simply introducing SiO2 nanoparticles (Comparative Example 2) can control the grain size to some extent, but it cannot solve the problems of uneven crystallization and numerous defects in traditional VCD processes. Based on this, ultrasonic-assisted treatment (Example 1) was introduced. Through the synergistic effect of the ultrasonic microfluidic field and nanoparticles, the crystallization kinetics of perovskite were effectively controlled, resulting in more uniform and oriented grain growth. This significantly reduced the pores and defects inside the film, optimized the overall microstructure, and provided a high-quality structural foundation for high-performance optoelectronic devices.

[0132] Furthermore, the perovskite thin film prepared according to the methods in Example 1 and Comparative Example 2 was used to prepare a perovskite solar cell; specifically, the perovskite solar cell includes: a substrate layer, a hole transport layer, a perovskite light absorption layer, an interface modification layer, a double electron transport layer (specifically including a first electron transport layer and a second electron transport layer), a hole blocking layer, and a metal electrode.

[0133] The perovskite light-absorbing layer is the perovskite thin film prepared in this invention (specifically, the perovskite thin film is prepared on the surface of the hole transport layer according to the method in Example 1 or Comparative Example 2 of this invention), with a thickness of 800 nm; the substrate layer is ITO (indium tin oxide), with a thickness of 200 nm; the hole transport layer is PEDOT:PSS (i.e., poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid)), with a thickness of 30 nm; the interface modification layer is EDADI (ethylenediamine diiodide), with a thickness of 5 nm; the first electron transport layer is PCBM (i.e., methyl [6,6]-phenyl-C61-butyrate), with a thickness of 50 nm; the second electron transport layer is C60 (i.e., fullerene), with a thickness of 30 nm; the hole blocking layer is BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), with a thickness of 5 nm; and the metal electrode is Ag (silver), with a thickness of 100 nm.

[0134] The perovskite thin film prepared according to the method in Comparative Example 2 was used to prepare a perovskite solar cell. The JV curve of the perovskite solar cell was tested, and the results are as follows. Figure 6 As shown.

[0135] The perovskite thin film prepared according to the method in Example 1 was used to prepare a perovskite solar cell, and the JV curve of the perovskite solar cell was tested. The results are as follows. Figure 7 As shown.

[0136] The perovskite thin film prepared according to the methods in Example 1 and Comparative Example 2 was used to prepare a perovskite solar cell, and its open-circuit voltage (V) was tested. OC ), short-circuit current density (J SC The results of fill factor (FF%) and photoelectric conversion efficiency (PCE%) are shown in Table 1 below:

[0137] Table 1 - Performance of different perovskite solar cells

[0138]

[0139] As shown in Table 1 above, the perovskite solar cell prepared by the perovskite thin film in Example 1 has a V1 OCCompared to Comparative Example 2, the voltage increased from 0.852 V to 0.886 V, representing a 3.99% improvement. This indicates that the ultrasonic-assisted process effectively reduced the defect density of the perovskite film, decreased the number of non-radiative recombination centers, thereby increasing the quasi-Fermi level difference of the device and significantly improving the open-circuit voltage. The J of the perovskite solar cell prepared from the perovskite film in Example 1... SC Compared to Comparative Example 2, from 32.04 mA / cm 2 Increased to 32.72 mA / cm 2 The efficiency improved by 2.12%. This is attributed to the improved crystal quality and uniformity of the thin film, which reduced recombination and loss of photogenerated carriers during transport, allowing for the effective collection of more photogenerated carriers. In Example 1, the FF of the perovskite solar cell prepared from the perovskite thin film increased from 77.60% to 81.50%, an improvement of 5.03%. This is one of the most significant performance improvements, indicating a significant reduction in series resistance and a significant increase in parallel resistance. The carrier transport efficiency and interface contact quality were greatly optimized, and the JV curve is closer to the ideal rectangle. In Example 1, the PCE of the perovskite solar cell prepared from the perovskite thin film increased from 21.19% to 23.62%, an improvement of 11.47%. This fully demonstrates the synergistic effect of ultrasound and SiO2 nanoparticles, which can fundamentally optimize the photoelectric performance of the perovskite thin film and achieve a significant breakthrough in device efficiency.

[0140] Compared to the simple VCD process, this invention optimizes the device from three dimensions—thin film crystal quality, interfacial electrical properties, and carrier transport efficiency—through the ultrasonic-assisted vacuum flash evaporation process in synergy with SiO2 nanoparticles. Ultimately, it achieves a significant improvement in photoelectric conversion efficiency, providing a reliable technical path for the fabrication of high-performance perovskite solar cells.

[0141] It is understood that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0142] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. A method for ultrasound-assisted preparation of perovskite thin films, characterized in that, Includes the following steps: Prepare perovskite precursor solution; The perovskite precursor solution is coated onto the substrate surface to form a wet film; The wet film is placed in a container, and the container is evacuated to bring the pressure inside the container to the first pressure. While evacuating, the wet film is ultrasonically treated. Then, pressure holding treatment is performed under the first pressure. Finally, gas is added to the container to bring the pressure to normal and maintained for a period of time to obtain a perovskite thin film.

2. The method for ultrasonic-assisted preparation of perovskite thin films as described in claim 1, characterized in that, The container is evacuated until the pressure inside reaches the first pressure within 3-4 seconds, which is 6-10 Pa.

3. The method for ultrasonic-assisted preparation of perovskite thin films as described in claim 1, characterized in that, The container is evacuated to bring the internal pressure to the first pressure, and the wet film is subjected to ultrasonic treatment. The process parameters controlled by the ultrasonic treatment are: ultrasonic frequency of 40~50KHz, ultrasonic power of 5~10W, and ultrasonic time of 10~15s.

4. The method for ultrasonic-assisted preparation of perovskite thin films as described in claim 2, characterized in that, Under the first pressure, a pressure holding process is performed for 20-25 seconds. In the step of replenishing the container with gas, the gas includes at least one of dry nitrogen, dry air, and dry carbon dioxide; Finally, gas is added to the container to atmospheric pressure and maintained for 15-30 seconds to obtain a perovskite thin film.

5. The method for ultrasonic-assisted preparation of perovskite thin films as described in claim 1, characterized in that, After adding gas to the container to atmospheric pressure and maintaining it for a period of time, the wet film is removed and subjected to heat treatment to obtain a perovskite thin film. The heat treatment temperature is 80~150℃ and the time is 10~20min.

6. The method for ultrasonic-assisted preparation of perovskite thin films as described in claim 1, characterized in that, The perovskite precursor solution includes a solvent, a precursor, and nanomaterials; The precursors include ammonium thiocyanate, stannous fluoride, cesium iodide, methylamine iodide, formamidinium iodide, stannous iodide, and lead iodide.

7. The method for ultrasonic-assisted preparation of perovskite thin films as described in claim 6, characterized in that, The solvent includes N,N-dimethylformamide and dimethyl sulfoxide; The nanomaterials include at least one of the following: metal oxide nanoparticles, sulfide quantum dots, selenide quantum dots, two-dimensional materials, carbon nanomaterials, metal nanoparticles, polymer nanoparticles, and metal-organic framework materials. The metal oxide nanoparticles include at least one of NiO2, ZnO, TiO2, SnO2, Al2O3, ZrO2, and HfO2; The sulfide quantum dots include at least one of PbS and CdS; The selenide quantum dots include at least one of PbSe and CdSe; The two-dimensional material includes at least one of graphene, graphene oxide, MXene, and h-BN; The carbon nanomaterials include at least one of CNTs and carbon quantum dots; The metal nanoparticles include at least one of Ag nanoparticles, Au nanoparticles, Ni nanoparticles, and Cu nanoparticles; The polymer nanoparticles include PMMA nanoparticles and PS nanospheres; The mass ratio of ammonium thiocyanate, stannous fluoride, cesium iodide, methylamine iodide, formamidinium iodide, stannous iodide, and lead iodide is (1~2):(12~15):(40~50):(80~90):(180~190):(330~340):(410~420); The volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is (2.5~3.5):1; The mass-to-volume ratio of ammonium thiocyanate to N,N-dimethylformamide is (1~2)g:(700~800)mL; The mass fraction of nanomaterials in the perovskite precursor solution is 0.05~0.15%.

8. The application of a perovskite thin film prepared by the method according to any one of claims 1 to 7 in the preparation of perovskite solar cells.

9. A perovskite solar cell, characterized in that, The perovskite thin film prepared by the method as described in any one of claims 1 to 7.

10. An apparatus for implementing the method for ultrasonic-assisted preparation of perovskite thin films according to any one of claims 1 to 7, characterized in that, include: A container, the interior of which is hollow to accommodate a wet film, and the container is provided with a vacuum port for connecting an external vacuum device to evacuate the container. An ultrasonic generator, located outside the container, is used to ultrasonically treat the wet film.

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