Method for preparing perovskite solar cell based on nanoimprint lithography

Abstract

The invention discloses a method for preparing a perovskite solar cell based on a nanoimprint technology, which belongs to the technical field of solar cell devices, and comprises the following steps: preparing a PDMS (Polydimethylsiloxane) soft film with a nano conical column structure on the surface, and then carrying out thermal nanoimprint on a perovskite thin film. The nano cone-column structure can induce regular and uniform growth of perovskite grains, so that the perovskite grains are regular in size and orderly arranged, and the grain boundary density and holes are reduced; and meanwhile, the nano conical column structure on the surface of the perovskite thin film can scatter incident light to increase the effective optical path length in the device, so that the light absorption of the device is enhanced, and the efficiency and the stability of the finally obtained perovskite solar cell are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of solar cell device technology, and in particular to a method for preparing perovskite solar cells based on nanoimprint technology. Background Technology

[0002] Perovskite solar cells possess significant advantages such as high absorption coefficient, tunable bandgap, low fabrication cost, and high carrier transport efficiency. Their power conversion efficiency (PCE) is gradually approaching that of traditional crystalline silicon solar cells, demonstrating great potential for commercial applications in next-generation photovoltaic technology. Accelerating the industrialization of perovskite solar cells and further improving their power conversion efficiency and long-term environmental stability have become core technological needs that urgently require solutions in this field. Introducing optical micro / nano structures into the solar cell structure to enhance light absorption efficiency is one of the industry's recognized effective technical strategies.

[0003] In existing technologies, nanoimprinting technology has been applied to the fabrication of micro and nanostructures for perovskite solar cells due to its simple process, low cost, and high reproducibility. For example, biomimetic moth-eye nanostructures of titanium dioxide (TiO2) and [6,6]-phenyl-C have been prepared using nanoimprinting technology. 61 methyl butyrate (PC) 61 BM can effectively enhance the light absorption capability of devices. At the same time, it was observed that the pressure-induced crystallization phenomenon in the nanoimprinting process can improve the crystal quality of perovskite films. For example, using cylindrical array templates to prepare whispering gable structures, or forming staggered moiré gratings between TiO2 and perovskite films through nanoimprinting, can not only significantly improve light absorption efficiency, but also increase the perovskite grain size and improve the film surface coverage.

[0004] However, existing perovskite solar cell fabrication methods based on nanoimprinting technology still suffer from key technical drawbacks: the perovskite grains formed after nanoimprinting have irregular morphologies and a wide grain size distribution, making it difficult to achieve uniform control over the shape and size of the perovskite grains. This drawback limits the improvement of the cell's energy conversion efficiency and also makes it difficult to meet the requirements for commercial applications in terms of long-term stability under complex environments. Therefore, how to optimize the nanoimprinting strategy to achieve uniform control of perovskite grains and simultaneously improve the energy conversion efficiency and environmental stability of the cell is a problem that needs to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a method for fabricating perovskite solar cells based on nanoimprint technology, in order to solve the above-mentioned problems.

[0006] This invention provides a method for fabricating perovskite solar cells based on nanoimprint technology, comprising the following steps:

[0007] S1. Preparation of nanoimprint templates:

[0008] Use a spin coater to spin coat positive photoresist onto a clean glass slide surface;

[0009] A beam splitter is used to split the laser emitted by a 325nm helium-cadmium laser into two beams. The angle between the two laser beams is adjusted so that they converge on the surface of the positive photoresist sample. After the first exposure, the glass slide is rotated for a second exposure.

[0010] The positive photoresist sample that has been exposed twice was soaked in positive photoresist developer and rinsed with deionized water to obtain a photoresist film with a nano-conical structure on the surface.

[0011] The polydimethylsiloxane (PDMS) solution and curing agent are mixed in proportion, stirred evenly, and then degassed. The mixture is then poured onto the surface of the photoresist film. The poured sample is cured in a high-temperature oven. After curing, it is peeled off to obtain a polydimethylsiloxane soft film with a nano-conical structure on the surface.

[0012] S2. Fabrication of perovskite solar cells:

[0013] The conductive glass substrate was ultrasonically cleaned in acetone and isopropanol for one hour in sequence, rinsed with deionized water and dried; the conductive glass substrate was then subjected to ultraviolet ozone treatment to enhance the surface hydrophilicity.

[0014] In a nitrogen-filled glove box, a hole transport layer solution is spin-coated onto a conductive glass substrate using a spin coater and then annealed to form a hole transport layer.

[0015] Lead iodide solution was spin-coated onto the surface of the hole transport layer and annealed. A cationic salt solution was spin-coated onto the lead iodide surface to form a perovskite precursor solution. After low-temperature pre-annealing, a perovskite precursor film was formed.

[0016] The polydimethylsiloxane soft film with a nanoconical structure on the surface obtained in step S1 is attached to the surface of the perovskite precursor film, and thermal nanoimprinting is performed using a nanoimprinter. After the process is completed, the film is peeled off to obtain a perovskite film with a nanoconical structure on the surface.

[0017] A passivating agent solution was spin-coated onto the surface of a perovskite thin film, and an electron transport layer, a hole blocking layer, and a metal electrode were sequentially deposited in a vacuum coating apparatus to complete the fabrication of a perovskite solar cell.

[0018] Preferably, in the above method for preparing perovskite solar cells based on nanoimprint technology, the positive photoresist in step S1 is S1805 positive photoresist, the spin coating rate is 3000 rpm, and the spin coating time is 30 s; the included angle between the two laser beams is 9.32°, the exposure time for each exposure is 40 ms, and the rotation angle of the sample after the first exposure is 90°.

[0019] Preferably, in the above method for preparing perovskite solar cells based on nanoimprint technology, the positive resist developer in step S1 is a tetramethylammonium hydroxide solution, and the development time is 3s.

[0020] Preferably, in the above method for preparing perovskite solar cells based on nanoimprint technology, the mass ratio of the polydimethylsiloxane solution to the curing agent in step S1 is 10:1, the stirring time is 5 min, the centrifugation at 8000 rpm for 3 min is used for degassing, the curing temperature is 95℃, and the curing time is 4 h.

[0021] Preferably, in the above method for preparing perovskite solar cells based on nanoimprint technology, the conductive glass substrate in step S2 is indium tin oxide (ITO) conductive glass, and the ultraviolet ozone treatment time is 15 min.

[0022] Preferably, in the above method for preparing perovskite solar cells based on nanoimprint technology, the hole transport layer in step S2 is prepared by dissolving poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) in toluene at a concentration of 2 mg / mL, and spin-coating it on a conductive glass substrate at a spin rate of 5000 rpm for 30 s, an annealing temperature of 100 °C, and an annealing time of 10 min.

[0023] Preferably, in the above method for preparing perovskite solar cells based on nanoimprint technology, the preparation method of the lead iodide solution in step S2 is as follows: 698 mg of lead iodide is dissolved in a mixed solvent of 935 μL of N,N-dimethylformamide (DMF) and 65 μL of dimethyl sulfoxide (DMSO), and the spin coating rate on the hole transport layer surface is 1600 rpm, the spin coating time is 30 s, the annealing temperature is 70 °C, and the annealing time is 45 s;

[0024] Preferably, in the above method for preparing perovskite solar cells based on nanoimprint technology, the preparation method of the cation salt solution in step S2 is as follows: 89 mg formamidinium hydroiodate (FAI), 8 mg methyl ammonium iodide (MAI), and 9 mg methyl ammonium chloride (MACl) are dissolved in 1 mL of isopropanol, and the spin coating rate on the lead iodide surface is 2300 rpm, the spin coating time is 30 s, the annealing temperature is 70 °C, and the annealing time is 1 min.

[0025] Preferably, in the above method for preparing perovskite solar cells based on nanoimprinting technology, the thermal nanoimprinting in step S2 uses a pressure of 3 bar, a temperature of 147°C, and a time of 15 min.

[0026] Preferably, in the above method for preparing perovskite solar cells based on nanoimprint technology, the passivating agent solution in step S2 is a hexafluoroisopropanol solution with a phenylethyl ammonium iodide (PEAI) concentration of 1.5 mg / mL; the spin coating rate is 4000 rpm; the spin coating time is 30 s; the annealing temperature is 100 °C; and the annealing time is 10 min; the vacuum degree of the vacuum coating instrument is 5 × 10⁻⁶. -4 Below Pa; the electron transport layer material is fullerene (C 60 ), the evaporation rate is The thickness is 23 nm; the hole blocking layer material is copper bath (BCP), and the evaporation rate is... The thickness is 7 nm; the metal electrode material is copper (Cu), and the evaporation rate is... The thickness is 100nm.

[0027] Therefore, this invention provides a method for fabricating perovskite solar cells based on nanoimprint technology. The nanoconical structure can effectively induce the directional growth of perovskite grains, resulting in a perovskite film with regular and uniform grain shapes and height, significantly reducing the grain boundary density. This reduction in grain boundary density directly suppresses the nonradiative recombination process of charge carriers, laying the microstructural foundation for improving the energy conversion efficiency of the battery and solving the core technical problem of irregular perovskite grain morphology and wide size distribution in existing nanoimprint technology. Furthermore, the nanoconical structure can efficiently scatter incident light, significantly extending the optical path length of the incident light within the battery device. This effect enables the device to achieve broad-spectrum light absorption enhancement in the visible light wavelength range, further supplementing the source of charge carriers and providing optical performance support for improving the battery's short-circuit current density and energy conversion efficiency.

[0028] Based on the synergistic effect of grain regulation and light absorption enhancement, the perovskite solar cell prepared by this invention achieves a significant improvement in energy conversion efficiency: the PCE of the optimal device reaches 23.78%, representing a 12.9% improvement compared to the control device without nanoimprinting, significantly outperforming the efficiency level of perovskite solar cells prepared using existing nanoimprinting technology. Furthermore, the long-term stability of the perovskite solar cell under complex environments is significantly optimized. After aging at 85°C for 1000 hours, the unencapsulated device retains over 80% of its initial efficiency, while the control device retains only 58% under the same conditions. After aging at 40% relative humidity for 600 hours, the unencapsulated device retains over 85% of its initial efficiency, while the control device retains only 33% under the same conditions. This improved stability stems from the homogenized perovskite grain structure reducing thin film porosity defects and effectively suppressing the erosion of the perovskite layer by moisture and heat, meeting the core requirement of environmental adaptability for the commercial application of perovskite solar cells.

[0029] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0030] Figure 1 This is a scanning electron microscope (SEM) image of the perovskite thin film with a nanoconical structure of the present invention.

[0031] Figure 2 This is a structural diagram of the perovskite solar cell device based on a perovskite thin film with a nanoconical structure according to the present invention.

[0032] Figure 3 The performance spectra of Example 1 (curve 1) and Comparative Example 1 (curve 2) are shown, where (a) is the absorption rate curve and (b) is the current density-voltage curve.

[0033] Figure 4 The stability tests for Example 1 (curve 1) and Comparative Example 1 (curve 2) are shown, where (a) is the thermal stability test curve and (b) is the humidity stability test curve. Detailed Implementation

[0034] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0036] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0037] This invention provides a method for fabricating perovskite solar cells based on nanoimprint technology, comprising the following steps:

[0038] S1. Preparation of nanoimprint templates:

[0039] Use a spin coater to spin coat positive photoresist onto a clean glass slide surface;

[0040] A beam splitter is used to split the laser emitted by a 325nm helium-cadmium laser into two beams. The angle between the two laser beams is adjusted so that they converge on the surface of the positive photoresist sample. After the first exposure, the glass slide is rotated for a second exposure.

[0041] The positive photoresist sample that has been exposed twice was soaked in positive photoresist developer and rinsed with deionized water to obtain a photoresist film with a nano-conical structure on the surface.

[0042] The polydimethylsiloxane solution and curing agent are mixed in proportion, stirred evenly, and then degassed. The mixture is then poured onto the surface of the photoresist film. The poured sample is cured in a high-temperature oven. After curing, the sample is peeled off to obtain a polydimethylsiloxane soft film with a nano-conical structure on the surface.

[0043] S2. Fabrication of perovskite solar cells:

[0044] The conductive glass substrate was ultrasonically cleaned in acetone and isopropanol for one hour in sequence, rinsed with deionized water and dried; the conductive glass substrate was then subjected to ultraviolet ozone treatment to enhance the surface hydrophilicity.

[0045] In a nitrogen-filled glove box, a hole transport layer solution is spin-coated onto a conductive glass substrate using a spin coater and then annealed to form a hole transport layer.

[0046] Lead iodide solution was spin-coated onto the surface of the hole transport layer and annealed. A cationic salt solution was spin-coated onto the lead iodide surface to form a perovskite precursor solution. After low-temperature pre-annealing, a perovskite precursor film was formed.

[0047] The polydimethylsiloxane soft film with a nanoconical structure on the surface obtained in step S1 is attached to the surface of the perovskite precursor film, and thermal nanoimprinting is performed using a nanoimprinter. After the process is completed, the film is peeled off to obtain a perovskite film with a nanoconical structure on the surface.

[0048] A passivating agent solution was spin-coated onto the surface of a perovskite thin film, and an electron transport layer, a hole blocking layer, and a metal electrode were sequentially deposited in a vacuum coating apparatus to complete the fabrication of a perovskite solar cell.

[0049] To further optimize the above technical solution, the spin coating rate of the positive photoresist in step S1 is 3000 rpm and the spin coating time is 30 s; the included angle of the two laser beams is 9.32°, the exposure time for each exposure is 40 ms, and the rotation angle of the sample after the first exposure is 90°.

[0050] To further optimize the above technical solution, the positive gel developer in step S1 is a tetramethylammonium hydroxide solution, and the development time is 3 seconds.

[0051] To further optimize the above technical solution, the mass ratio of polydimethylsiloxane solution to curing agent in step S1 is 10:1, the stirring time is 5 min, the centrifugation at 8000 rpm for 3 min is used for degassing, the curing temperature is 95℃, and the curing time is 4 h.

[0052] To further optimize the above technical solution, the conductive glass substrate in step S2 is indium tin oxide conductive glass, and the ultraviolet ozone treatment time is 15 minutes.

[0053] To further optimize the above technical solution, the hole transport layer in step S2 is prepared by dissolving poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] in toluene at a concentration of 2 mg / mL, and spin-coating it on a conductive glass substrate at a spin rate of 5000 rpm for 30 s, an annealing temperature of 100℃, and an annealing time of 10 min.

[0054] To further optimize the above technical solution, the preparation method of the lead iodide solution in step S2 is as follows: 698 mg of lead iodide is dissolved in a mixed solvent of 935 μL N,N-dimethylformamide and 65 μL dimethyl sulfoxide, and the spin coating rate on the hole transport layer surface is 1600 rpm, the spin coating time is 30 s, the annealing temperature is 70 ℃, and the annealing time is 45 s.

[0055] To further optimize the above technical solution, the preparation method of the cation salt solution in step S2 is as follows: 89 mg formamidin hydroiodate, 8 mg methyl ammonium iodide, and 9 mg methyl ammonium chloride are dissolved in 1 mL of isopropanol. The spin coating rate on the lead iodide surface is 2300 rpm, the spin coating time is 30 s, the annealing temperature is 70 °C, and the annealing time is 1 min.

[0056] To further optimize the above technical solution, the thermal nanoimprinting in step S2 uses a pressure of 3 bar, a temperature of 147°C, and a time of 15 min.

[0057] To further optimize the above technical solution, the passivating agent solution in step S2 is a hexafluoroisopropanol solution with a phenylethyl ammonium iodide concentration of 1.5 mg / mL, the spin coating speed is 4000 rpm, the spin coating time is 30 s, the annealing temperature is 100℃, and the annealing time is 10 min; the vacuum degree of the vacuum coating instrument is 5 × 10⁻⁶. -4 Pa or less; the electron transport layer material is fullerene, and the evaporation rate is [missing value]. The thickness is 23 nm; the hole blocking layer material is copper bath resin, and the evaporation rate is... The thickness is 7 nm; the metal electrode material is copper, and the evaporation rate is... The thickness is 100nm.

[0058] To provide a clearer and more detailed description of the method for fabricating perovskite solar cells based on nanoimprint technology provided in the embodiments of the present invention, specific embodiments will be described below.

[0059] Example 1

[0060] By nanoimprinting perovskite thin films with PDMS soft films possessing nanoconical structures, the crystallinity quality of the perovskite films is optimized, thereby improving the light absorption of perovskite solar cells and fabricating perovskite solar cells with high performance and stability. The specific steps are as follows:

[0061] Preparation of nanoimprint templates:

[0062] Positive photoresist S1805 was spin-coated onto a clean glass slide using a spin coater. A 325nm helium-cadmium laser was split into two beams using a beam splitter, and the angle between the two beams was adjusted to 9.32° to converge them onto the positive photoresist sample surface. After exposure for 40ms, the sample was rotated 90° and exposed again for 40ms. Development was performed using tetramethylammonium hydroxide solution, followed by rinsing with deionized water. PDMS solution and curing agent were mixed at a 10:1 mass ratio for 5 minutes and centrifuged at 8000rpm for 3 minutes to degas. This mixture was then poured onto the photoresist film surface and cured in a 95°C oven for 4 hours. The cured PDMS film was then peeled off.

[0063] Fabrication of perovskite solar cells:

[0064] The ITO conductive glass substrate was ultrasonically cleaned sequentially in acetone and isopropanol for one hour, rinsed with deionized water, and dried. The ITO conductive glass substrate was then subjected to UV ozone treatment for 15 minutes. In a nitrogen-filled glove box, a 2 mg / mL PTAA toluene solution was spin-coated onto the substrate using a spin coater and annealed on a 100°C hot plate for 10 minutes. Subsequently, a 698 mg / mL lead iodide DMF / DMSO solution was spin-coated at 1600 rpm for 30 seconds and annealed on a 70°C hot plate for 45 seconds. A cationic salt solution of 89 mg FAI, 8 mg MAI, and 9 mg MACl dissolved in 1 mL isopropanol was spin-coated onto the lead iodide film surface at 2300 rpm for 30 seconds and pre-annealed on a 70°C hot plate for 1 minute. A PDMS soft film was then attached to the perovskite film surface and thermally nanoimprinted at 147°C and 3 bar for 15 minutes. After the nanoimprinting was completed, the PDMS soft film was peeled off. A 1.5 mg / mL PEAI solution in hexafluoroisopropanol was spin-coated onto the perovskite film surface at a rate of 4000 rpm for 30 s, followed by annealing on a hot plate at 100 °C for 10 min. The annealing was then carried out under a vacuum of less than 5 × 10⁻⁶. -4 23nm C is deposited in a vacuum coating apparatus with a pressure below Pa. 60 7nm BCP, 100nm copper, evaporation rates are respectively

[0065] Comparative Example 1

[0066] The fabrication method of perovskite solar cells is as follows:

[0067] The ITO conductive glass substrate was ultrasonically cleaned sequentially in acetone and isopropanol for one hour, rinsed with deionized water, and dried. The ITO conductive glass substrate was then subjected to UV ozone treatment for 15 minutes. In a nitrogen-filled glove box, a 2 mg / mL toluene solution of PTAA was spin-coated onto the surface using a spin coater and annealed on a 100°C hot plate for 10 minutes. Subsequently, a 698 mg / mL DMF / DMSO solution of lead iodide was spin-coated at 1600 rpm for 30 seconds and annealed on a 70°C hot plate for 45 seconds. A cationic salt solution of 89 mg FAI, 8 mg MAI, and 9 mg MACl dissolved in 1 mL isopropanol was spin-coated onto the lead iodide film surface at 2300 rpm for 30 seconds, pre-annealed on a 70°C hot plate for 1 minute, and then annealed in air at 147°C for 15 minutes. A 1.5 mg / mL PEAI solution in hexafluoroisopropanol was spin-coated onto the perovskite film surface at a rate of 4000 rpm for 30 s, followed by annealing on a hot plate at 100 °C for 10 min. The annealing was then carried out under a vacuum of less than 5 × 10⁻⁶. -4 23nm C is deposited in a vacuum coating apparatus with a pressure below Pa. 60 7nm BCP, 100nm copper, evaporation rates are respectively

[0068] The perovskite solar cells obtained in Example 1 and Comparative Example 1 were subjected to performance and stability tests, and the results were compared as follows:

[0069] like Figure 3 As shown in (a), the absorbance curves of the perovskite solar cells prepared in Example 1 and Comparative Example 1 were measured using a spectrophotometer with an integrating sphere. In Example 1, the nanopillars on the surface of the nanoimprinted perovskite film have a period of approximately 2 micrometers, which can significantly scatter visible light. This light scattering increases the optical path length and promotes light absorption in the device. The device in Example 1 achieved broad-spectrum absorption enhancement in the visible light wavelength range. Figure 3 (b) shows the current density-voltage curves of the perovskite solar cells prepared in Example 1 and Comparative Example 1. The device prepared in Example 1 showed significantly improved open-circuit voltage and short-circuit current density, achieving a power conversion efficiency of 23.78%, while the device prepared in Comparative Example 1 had a power conversion efficiency of 21.06%, representing an improvement of 12.9%. This indicates that the nanoimprinted perovskite film strategy of Example 1 is feasible for improving the performance of perovskite solar cells.

[0070] like Figure 4 As shown in (a), the perovskite solar cells prepared in Example 1 and Comparative Example 1, placed unencapsulated in a dark nitrogen environment at 85°C (ISOS-D-2 protocol), show the change in power conversion efficiency over aging time. After aging for 1000 hours, the efficiencies of the perovskite solar cells prepared in Example 1 and Comparative Example 1 were 80% and 58% of their initial efficiencies, respectively. Figure 4 (b) shows the perovskite solar cells prepared in Example 1 and Comparative Example 1, placed unencapsulated in a dark nitrogen environment with 40% relative humidity (ISOS-D-1 protocol), and the change in power conversion efficiency with aging time. After aging for 600 hours, the efficiencies of the perovskite solar cells prepared in Example 1 and Comparative Example 1 were 85% and 33% of their initial efficiencies, respectively. In Example 1, the idealized grain shape in the nanoimprinted perovskite film is uniformly arranged, which can reduce the grain boundary density and pore defects of the perovskite film, thereby inhibiting moisture from entering the perovskite layer and significantly improving the thermal and humidity stability of the device.

[0071] Therefore, this invention provides a method for fabricating perovskite solar cells based on nanoimprint technology. The nanoconical structure can effectively induce the directional growth of perovskite grains, resulting in a perovskite film with regular and uniform grain shapes and height, significantly reducing the grain boundary density. This reduction in grain boundary density directly suppresses the nonradiative recombination process of charge carriers, laying the microstructural foundation for improving the energy conversion efficiency of the battery and solving the core technical problem of irregular perovskite grain morphology and wide size distribution in existing nanoimprint technology. Furthermore, the nanoconical structure can efficiently scatter incident light, significantly extending the optical path length of the incident light within the battery device. This effect enables the device to achieve broad-spectrum light absorption enhancement in the visible light wavelength range, further supplementing the source of charge carriers and providing optical performance support for improving the battery's short-circuit current density and energy conversion efficiency. Based on the synergistic effect of grain regulation and light absorption enhancement, the perovskite solar cell prepared by this invention achieves a significant improvement in energy conversion efficiency: the PCE of the optimal device reaches 23.78%, representing a 12.9% improvement compared to the control device without nanoimprinting, significantly outperforming the efficiency level of perovskite solar cells prepared using existing nanoimprinting technology. Furthermore, the long-term stability of the perovskite solar cell under complex environments is significantly optimized. After aging at 85°C for 1000 hours, the unencapsulated device retains over 80% of its initial efficiency, while the control device retains only 58% under the same conditions. After aging at 40% relative humidity for 600 hours, the unencapsulated device retains over 85% of its initial efficiency, while the control device retains only 33% under the same conditions. This improved stability stems from the homogenized perovskite grain structure reducing thin film porosity defects and effectively suppressing the erosion of the perovskite layer by moisture and heat, meeting the core requirement of environmental adaptability for the commercial application of perovskite solar cells.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a perovskite solar cell based on nanoimprint technology, characterized in that, The method comprises the following steps: S1, preparation of a nano-imprint template: A positive photoresist is spin-coated on the surface of a clean glass sheet using a spin coater; A helium-cadmium laser emitting laser light with a wavelength of 325 nm is split into two beams using a beam splitter, and the included angle of the two laser beams is adjusted so that they converge on the surface of the positive photoresist sample; after the first exposure, the glass sheet is rotated for the second exposure; The positive photoresist sample subjected to the two exposures is immersed in a positive photoresist developer and rinsed with deionized water to obtain a photoresist film with a nano-cone column structure on the surface; A polydimethylsiloxane solution is mixed with a curing agent in a certain proportion, stirred uniformly, and then degassed; the degassed solution is then cast on the surface of the photoresist film, and the cast sample is cured in a high-temperature oven; after curing, the sample is peeled off to obtain a polydimethylsiloxane soft film with a nano-cone column structure on the surface; S2, preparation of a perovskite solar cell: The conductive glass substrate is ultrasonically cleaned in acetone and isopropyl alcohol for one hour, rinsed with deionized water, and dried; the conductive glass substrate is subjected to ultraviolet ozone treatment to enhance the surface hydrophilicity; In a nitrogen-filled glove box, a hole transport layer solution is spin-coated on the conductive glass substrate using a spin coater and annealed to form a hole transport layer; A lead iodide solution is spin-coated on the surface of the hole transport layer and annealed, a cationic salt solution is spin-coated on the surface of the lead iodide to form a perovskite precursor solution, and a perovskite precursor film is formed after low-temperature pre-annealing; The polydimethylsiloxane soft film with a nano-cone column structure obtained in step S1 is attached to the surface of the perovskite precursor film, and hot nano-imprinting is performed using a nano-imprinting machine; after completion, the sample is peeled off to obtain a perovskite film with a nano-cone column structure on the surface; A passivation agent solution is spin-coated on the surface of the perovskite film, and an electron transport layer, a hole blocking layer, and a metal electrode are sequentially evaporated in a vacuum coating instrument to complete the preparation of the perovskite solar cell. 2.The method of claim 1, wherein the method is characterized by, In step S1, the spin-coating rate of the positive photoresist is 3000 rpm, and the spin-coating time is 30 s; the included angle of the two laser beams is 9.32°, and the exposure time for each exposure is 40 ms; the sample is rotated by 90° after the first exposure. 3.The method of claim 1, wherein the method is characterized by, In step S1, the positive photoresist developer is a tetramethylammonium hydroxide solution, and the developing time is 3 s. 4.The method of claim 1, wherein the method is characterized by, In step S1, the mass ratio of the polydimethylsiloxane solution to the curing agent is 10:1, the stirring time is 5 min, the degassing is performed in a centrifuge at a speed of 8000 rpm for 3 min, the curing temperature is 95℃, and the curing time is 4 h. 5.The method of claim 1, wherein the method is characterized by, In step S2, the conductive glass substrate is an indium tin oxide conductive glass, and the ultraviolet ozone treatment time is 15 min. 6.The method of claim 1, wherein the method is characterized by, In step S2, the hole transport layer is prepared by dissolving poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] in toluene at a concentration of 2 mg / mL, spin-coating the solution on the conductive glass substrate at a speed of 5000 rpm for 30 s, and annealing at a temperature of 100℃ for 10 min. 7.The method of claim 1, wherein the method further comprises: depositing a perovskite layer on the substrate; and depositing a back electrode layer on the perovskite layer. The preparation method of the lead iodide solution in step S2 is: 698 mg of lead iodide is dissolved in a mixed solvent of 935 μL of N,N-dimethylformamide and 65 μL of dimethyl sulfoxide, the spin coating rate on the surface of the hole transport layer is 1600 rpm, the spin coating time is 30 s, the annealing temperature is 70 °C, and the annealing time is 45 s. 8.The method of claim 1, wherein the method is characterized by, The preparation method of the cationic salt solution in step S2 is: 89 mg of formamidinium hydroiodide, 8 mg of methylammonium iodide, and 9 mg of methylammonium chloride are dissolved in 1 mL of isopropanol, the spin coating rate on the surface of the lead iodide is 2300 rpm, the spin coating time is 30 s, the annealing temperature is 70 °C, and the annealing time is 1 min. 9.The method of claim 1, wherein the method further comprises, after the forming of the perovskite layer, a step of forming a back electrode layer on the perovskite layer. The thermal nanoimprinting in step S2 uses a pressure of 3 bar, a temperature of 147 °C, and a time of 15 min. 10.The method of claim 1, wherein the method is characterized by, The passivation agent solution in step S2 is a hexafluoroisopropanol solution with a concentration of 1.5 mg / mL of phenethylammonium iodide, the spin coating rate is 4000 rpm, the spin coating time is 30 s, the annealing temperature is 100 ℃, and the annealing time is 10 min; the vacuum degree of the vacuum coating machine is 5 × 10 -4 Pa below; the electron transport layer material is fullerene, the evaporation rate is 23 nm; the hole blocking layer material is bathocuproin, the evaporation rate is 7 nm; the metal electrode material is copper, the evaporation rate is 100 nm.

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