Perovskite solar cell and method of manufacturing the same

Abstract

This invention relates to the field of photovoltaic solar cells and discloses a perovskite solar cell and its fabrication method. The perovskite solar cell includes a perovskite active layer; micro-nano cavity structures (4-1) are formed on the perovskite active layer, and the micro-nano cavity structures (4-1) have serrated sidewalls. By forming micro-nano cavity structures, the perovskite solar cell of this invention enables photolocalization of incident light within the active layer, thereby improving the utilization efficiency of sunlight.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic solar cells, specifically to a perovskite solar cell that enhances light absorption through a micro-nano cavity structure and its fabrication method. Background Technology

[0002] With the rapid increase in global energy consumption and the growing severity of environmental pollution, more and more research is focusing on the development and utilization of new energy sources. Solar energy, as a clean and inexhaustible source, has always attracted significant attention. Currently, the solar photovoltaic industry has achieved commercialization for various material types, such as monocrystalline silicon, polycrystalline silicon, cadmium telluride, and gallium arsenide solar cells. These types of solar cells have good photoelectric conversion efficiency, long lifespan, and high stability. However, the fabrication of these cells generally requires complex processes, resulting in severe environmental pollution and high costs.

[0003] Since 2009, perovskite has been successfully used in the fabrication of solar cells (Kojima A, Teshima K, Shirai Y and Miyasaka T. Journal of American Chemical Society. 2009, 131). Perovskite solar cells have always been a research hotspot. Perovskite materials are direct bandgap semiconductors, possessing high carrier mobility, large light absorption coefficient, long carrier diffusion length, and tunable bandgap. The simple fabrication process makes perovskite fabrication relatively inexpensive. He Zhubing's research group used alkali metal salts to suppress hole transport layer interface recombination, obtaining perovskite films with good orientation and low defect density. The efficiency of the perovskite solar cells fabricated was 21% (Wei Chen, Yecheng Zhou, Zhubing He et al. Adv. Energy Mater. 2018, 03872). Huang Wei's research group used a green antisolvent to prepare a high-quality perovskite thin film with a smooth surface and no voids, and obtained a perovskite solar cell with a high efficiency of 23.7% (Yikai Yun, Fangfang Wang, Wei Huang, et al. Adv. Mater. 2019, 07123).

[0004] In the currently reported literature, most of the perovskite solar cells studied are planar, unstructured polycrystalline thin films. These perovskite films have limited light absorption efficiency, resulting in some loss of light energy. Planar perovskites also have more defects than structured perovskites, which further limits the improvement of perovskite solar cell efficiency. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned problems existing in the prior art and provide a perovskite solar cell and its preparation method. The perovskite solar cell has a micro-nano cavity structure, which enables incident light to undergo photolocalization in the active layer, thereby improving the utilization efficiency of sunlight.

[0006] To achieve the above objectives, the present invention provides a perovskite solar cell comprising a perovskite active layer; wherein a micro-nano cavity structure is formed on the perovskite active layer, and at least a portion of the sidewalls of the micro-nano cavity structure is a serrated sidewall.

[0007] Preferably, the angle of the serrated sidewall is 20°-160°, and more preferably 50°-70°.

[0008] Preferably, the zigzag sidewalls have evenly distributed bends.

[0009] Preferably, the size of the micro-nano cavity structure is 10nm-100μm and the depth is 20-300nm.

[0010] Preferably, the area of ​​the micro-nano cavity structure accounts for 40-60% of the area of ​​the perovskite active layer surface;

[0011] Preferably, the micro-nano cavity structure is formed as a micro-nano cavity array structure.

[0012] Preferably, the perovskite solar cell comprises a substrate layer, a transparent conductive layer, a hole transport layer, a perovskite active layer, an electron transport layer, and a hole blocking layer, and electrodes, which are stacked sequentially.

[0013] Preferably, the perovskite active layer has a micro-nano cavity structure formed on its surface away from the substrate layer.

[0014] Preferably, the substrate layer is a rigid substrate or a flexible substrate; more preferably, the substrate layer is one or more of ITO conductive glass, FTO conductive glass, PEN film, PET film, aluminum foil, and copper foil.

[0015] Preferably, the material of the hole transport layer is PEDOT:PSS, Spiro-OMeTAD, PTAA, or NiO. x One or more of the following, preferably NiO x .

[0016] Preferably, the material of the perovskite active layer is one or more of CH3NH3PbI3, CH3NH3PbBr3, CH3NH3PbCl3, CsPbI3, FAPbI3, FAPbI3, CsSnI3, CsPbBr3, CsPbCl3, CH3NH3PbBr2I, and CH3NH3PbBrI2.

[0017] Preferably, the material of the electron transport layer is one or more of TiO2, SnO2, PC61BM, PC71BM, and C60.

[0018] A second aspect of the present invention provides a method for fabricating a perovskite solar cell, the method comprising: forming a micro-nano cavity structure on the surface of the perovskite active layer during the process of forming a perovskite active layer using a perovskite precursor, wherein at least a portion of the sidewalls of the micro-nano cavity structure are serrated sidewalls.

[0019] Preferably, the angle of the serrated sidewall is 20°-160°, and more preferably 50°-70°.

[0020] Preferably, the size of the micro-nano cavity structure is 10nm-100μm and the depth is 20-300nm.

[0021] Preferably, the area of ​​the micro-nano cavity structure accounts for 50-70% of the area of ​​the perovskite active layer surface.

[0022] Preferably, the method includes:

[0023] (1) Hole transport layer is prepared on a substrate and a transparent conductive layer using hole transport materials;

[0024] (2) A perovskite active layer is formed on the hole transport layer using a perovskite precursor, and a micro-nano cavity structure is formed on the surface of the perovskite active layer.

[0025] (3) An electron transport layer is formed on the perovskite active layer using an electron transport material.

[0026] Preferably, one or more of the following methods are used to form micro-nano cavity structures on the surface of the perovskite active layer: nanoimprinting, laser etching, plasma treatment, ion beam etching, and magnetron sputtering.

[0027] Preferably, the substrate layer is a rigid substrate or a flexible substrate; more preferably, the substrate layer is one or more of ITO conductive glass, FTO conductive glass, PEN film, PET film, aluminum foil, and copper foil.

[0028] Preferably, the material of the hole transport layer is PEDOT:PSS, Spiro-OMeTAD, PTAA, or NiO.x One or more of the following, preferably NiO x .

[0029] Preferably, the material of the perovskite active layer is one or more of CH3NH3PbI3, CH3NH3PbBr3, CH3NH3PbCl3, CsPbI3, FAPbI3, FAPbI3, CsSnI3, CsPbBr3, CsPbCl3, CH3NH3PbBr2I, and CH3NH3PbBrI2.

[0030] Preferably, the material of the electron transport layer is one or more of TiO2, SnO2, PC61BM, PC71BM, and C60.

[0031] By constructing a zig-zag structure and related deformations in the perovskite active layer, incident light undergoes optical localization within the active layer. This alters the straight-line path of the light rays through the absorbing layer, increasing the light propagation path and improving the utilization efficiency of sunlight. The beneficial effects of this invention are:

[0032] (1) This invention improves the crystal quality of the perovskite layer, reduces the defect density, increases the propagation path of light in the perovskite layer, and prepares a perovskite solar cell with high efficiency, good stability and almost zero hysteresis.

[0033] (2) The present invention uses a micro-nano cavity structure, which significantly improves the optical localization effect of the device, thereby improving the battery efficiency.

[0034] (3) The high-performance perovskite solar cell of the present invention has a micro-nano cavity structure that is universally applicable to a variety of substrates and different perovskite active layers.

[0035] (4) The high-performance perovskite solar cell of the present invention has the advantages of simple preparation process and low cost, and has great application prospects in the fields of perovskite solar cells, wearable devices, portable mobile power supplies, etc. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the perovskite solar cell structure of the present invention.

[0037] Figure 2 This is an optical photograph of the silicon template used in Embodiment 1 of the present invention.

[0038] Figure 3 This is an optical photograph of the perovskite active layer with micro-nano cavity structure embossed in Embodiment 1 of the present invention.

[0039] Figure 4This is a SEM image of the perovskite active layer (perovskite polycrystalline thin film) with micro-nano cavity structure imprinted in Embodiment 1 of the present invention.

[0040] Figure 5 The image shows the XRD pattern of the perovskite active layer with micro-nano cavity structure embossed in Example 1 of the present invention.

[0041] Figure 6 The absorption spectra are those of perovskite solar cells with serrated micro-nano cavity structures imprinted with different angles in Examples 1 and 2 of the present invention.

[0042] Figure 7 The images show the reflection spectra of perovskite solar cells with serrated micro-nano cavity structures imprinted with different angles in Examples 1 and 2 of the present invention.

[0043] Figure 8 The light capture efficiency spectra of the perovskite solar cells of Example 1 and the control of the present invention are shown.

[0044] Figure 9 The images show the localized light simulation diagrams obtained by FDTD software for the perovskite solar cells of Example 1 (right) and the control (left) of the present invention.

[0045] Figure 10 This is an IV curve of the perovskite solar cell of Example 1 of the present invention.

[0046] Figure 11 This is an IV curve of the perovskite solar cell of Comparative Example 1 of the present invention.

[0047] Figure 12 This is the IV curve of the perovskite solar cell of Comparative Example 2 of the present invention.

[0048] Explanation of reference numerals in the attached figures

[0049] 1. Substrate layer 2. Transparent conductive layer 3. Hole transport layer

[0050] 4. Perovskite active layer; 5. Electron transport layer; 6. Hole blocking layer

[0051] 4-1. Micro-nano cavity structure Detailed Implementation

[0052] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0053] In this invention, unless otherwise stated, directional terms such as "upper" and "lower" are used to describe the directions shown in the accompanying drawings, but these directional terms should not constitute a limitation on the scope of protection of this invention.

[0054] The present invention provides a perovskite solar cell, which includes a perovskite active layer 4; wherein, a micro-nano cavity structure 4-1 is formed on the surface of the perovskite active layer 4, and at least a portion of the sidewalls of the micro-nano cavity structure 4-1 is a serrated sidewall.

[0055] In this invention, "serrated sidewalls" refers to the sidewalls of the micro / nano cavity structure being composed of serrated lines in a top view. By forming such serrated sidewalls, incident light undergoes reflection and scattering when passing through the micro / nano cavity structure, thereby altering the path of light rays as they travel in a straight line through the perovskite active layer and light-absorbing layer. This increases the light propagation path and achieves light localization, allowing the light-absorbing layer to absorb more light energy, improving the utilization efficiency of sunlight and compensating for the disadvantage of a thin light-absorbing layer. Perovskite solar cells prepared in this way exhibit high efficiency, good stability, near-zero hysteresis, and good repeatability.

[0056] The micro-nano cavity structure 4-1 can be formed on any surface or two surfaces of the perovskite active layer 4. Preferably, the micro-nano cavity structure is formed on the light incident surface of the perovskite active layer 4, that is, on the surface of the perovskite active layer 4 away from the substrate layer.

[0057] In a top view, the micro-nano cavity structure 4-1 can generally be rectangular, circular, triangular, polygonal, etc., and at least a portion of its sides are composed of zigzag lines. Preferably, the micro-nano cavity structure 4-1 can generally be rectangular, and at least two long sides are composed of zigzag lines. Figure 3 This illustrates a case where the micro-nano cavity structure 4-1 is a rectangle with two long sides composed of zigzag lines. Furthermore, to facilitate the fabrication of the micro-nano cavity structure 4-1, it is preferable that each individual micro-nano cavity structure 4-1 is formed in a generally cylindrical shape.

[0058] In this invention, the bend angle θ of the serrated sidewall refers to the included angle between adjacent serrated line segments constituting the serrated sidewall. To improve the localized optical performance of the micro / nano cavity structure, preferably, the bend angle θ of the serrated sidewall is 20°-160°, more preferably 50°-70°, and even more preferably 55°-65°. The lengths of the line segments between bend angles θ can be equal or unequal, preferably equal, or obtained through a certain variation pattern, such as alternating lengths.

[0059] According to the present invention, the size of the micro-nano cavity structure 4-1 (expressed as the distance between the two farthest points on the edge of a single micro-nano cavity structure in a top view) can be 10 nm-100 μm, preferably 20 μm; the depth can be 20-300 nm, preferably 50-150 nm. Furthermore, the serration length of the serrated sidewall is preferably 400 nm-10 μm, more preferably 1 μm-5 μm, for example 5 μm.

[0060] According to the present invention, the area of ​​the micro-nano cavity structure 4-1 accounts for 40-60%, preferably 40-50%, relative to the area of ​​the surface of the perovskite active layer 4. For ease of description, the "area ratio of the micro-nano cavity structure 4-1 relative to the area of ​​the surface of the perovskite active layer 4" is simply referred to as "area ratio".

[0061] More preferably, the micro-nano cavity structure 4-1 is formed as a micro-nano cavity array structure, such as... Figure 2-4 As shown. In the micro-nano cavity array structure, the distance between each micro-nano cavity structure 4-1 can be 5-100μm, preferably 10-25μm.

[0062] By constructing the micro-nano cavity structure 4-1 in the manner described above, the localized light performance of the perovskite active layer 4 can be further improved, thereby enhancing the efficiency and stability of the fabricated perovskite solar cell.

[0063] According to a preferred embodiment of the present invention, such as Figure 1 As shown, the perovskite solar cell includes a substrate layer 1, a transparent conductive layer 2, a hole transport layer 3, a perovskite active layer 4, an electron transport layer 5, and a hole blocking layer 6, stacked sequentially, as well as electrodes (including a cathode and an anode). Preferably, micro-nano recessed structures are formed on the surface of the perovskite active layer 4 away from the substrate layer.

[0064] In this invention, the materials and methods for forming the substrate layer 1, transparent conductive layer 2, hole transport layer 3, perovskite active layer 4, electron transport layer 5, hole blocking layer 6, and electrodes are not particularly limited, and can be formed using any materials and methods suitable for the corresponding layers of perovskite solar cells.

[0065] The substrate layer 1 can be a rigid substrate or a flexible substrate. Preferably, the substrate layer 1 is one or more of ITO conductive glass, FTO conductive glass, PEN film, PET film, aluminum foil, and copper foil, with ITO conductive glass being the most preferred. The thickness of the substrate layer 1 can be 0.1-1 μm, preferably 0.4-0.6 μm, for example, 0.5 μm.

[0066] The hole transport material used to form the hole transport layer 3 can be PEDOT:PSS, Spiro-OMeTAD, PTAA, or NiO. x One or more of the following, preferably NiO x .

[0067] The material forming the perovskite active layer 4 can be one or more of CH3NH3PbI3, CH3NH3PbBr3, CH3NH3PbCl3, CsPbI3, FAPbI3, FAPbI3, CsSnI3, CsPbBr3, CsPbCl3, CH3NH3PbBr2I, and CH3NH3PbBrI2. The above materials can be coated in the form of a perovskite precursor solution, forming a micro / nano cavity structure before curing. The thickness of the perovskite active layer 4 can be 0.25-1 μm, preferably 0.3-0.4 μm, for example, 0.35 μm.

[0068] The electron transport material forming the electron transport layer 5 can be one or more of TiO2, SnO2, PC61BM, PC71BM, and C60, preferably PC61BM. The thickness of the electron transport layer 5 can be 20-180 nm, preferably 30-70 nm, for example, 50 nm.

[0069] According to the present invention, the electrode includes an anode and a cathode. Preferably, the anode is formed on a transparent conductive layer 2, and the cathode is formed on an electron transport layer 5. The material forming the electrode is one or more of gold, silver, and copper, preferably gold.

[0070] The second aspect of the present invention provides a method for preparing a perovskite solar cell, the method comprising: forming a micro-nano cavity structure 4-1 on the surface of the perovskite active layer 4 during the process of forming a perovskite active layer 4 using a perovskite precursor, wherein at least a portion of the sidewalls of the micro-nano cavity structure 4-1 are serrated sidewalls.

[0071] According to a specific embodiment of the present invention, the method for fabricating the perovskite solar cell may include:

[0072] (1) Hole transport layer 3 is prepared on substrate 1 and transparent conductive layer 2 using hole transport material;

[0073] (2) A perovskite active layer 4 is formed on the hole transport layer 3 using a perovskite precursor, and a micro-nano cavity structure 4-1 is formed on the surface of the perovskite active layer 4.

[0074] (3) An electron transport layer 5 is formed on the perovskite active layer 4 using an electron transport material.

[0075] According to the present invention, the micro-nano cavity structure 4-1 can be formed by imprinting, laser etching, plasma treatment, ion beam etching, or magnetron sputtering. Preferably, the micro-nano cavity structure 4-1 is formed on the surface of the perovskite active layer 4 using nanoimprinting. Specifically, a template can be prepared according to the shape and arrangement of the micro-nano cavity structure 4-1 to be formed, for use in nanoimprinting. The template material used to form the micro-nano cavity structure 4-1 can be one of the following: metallic materials, inorganic materials, polymeric materials, or composite materials, preferably PDMS (polydimethylsiloxane), PC (polycarbonate), silicon, etc.

[0076] The shape and size of the micro-nano recessed structure 4-1, as well as the forming materials and sizes of the substrate layer 1, transparent conductive layer 2, hole transport layer 3, perovskite active layer 4, electron transport layer 5, hole blocking layer 6, and electrodes, are the same as those of the perovskite solar cell of the first aspect of the present invention, and will not be repeated here.

[0077] According to the present invention, the hole transport layer 3, the perovskite active layer 4, the electron transport layer 5, and the hole blocking layer 6 can all be prepared by coating.

[0078] According to the present invention, the preparation method of the perovskite active layer 3 includes, but is not limited to, one-step method, two-step method, dynamic two-step method, etc., preferably one-step method. Specifically, a perovskite precursor solution can be coated onto the hole transport layer 3, and after 3-6 seconds, solvents such as toluene, chlorobenzene, and xylene are added to rapidly crystallize the perovskite, forming the perovskite active layer 3. The volume ratio of the precursor solution to the solvent can be 100:1-5. Furthermore, in order to form the desired micro / nano cavity structure 4-1, the micro / nano cavity structure 4-1 needs to be rapidly formed after the addition of solvent to promote rapid crystallization of the perovskite.

[0079] The preparation steps of the above-mentioned perovskite precursor solution may include: dissolving CH3NH3A:PbA2 in a molar ratio of 1:1 in a mixed solution of DMF (N,N-dimethylformamide) and DMSO (dimethyl sulfoxide) (e.g., a mixed solution of DMF:DMSO = 4:1), and then heating and stirring at 50-80°C for more than 6 hours to form a perovskite precursor solution with a concentration of 300-600 mg / ml, wherein A represents I, Cl, or Br. By using the above ratio and by means of heating and stirring, the materials can be fully miscible, so as to ensure that the perovskite active layer 3 can react fully during the preparation process and reduce the residual PbI2, PbCl2, or PbBr2. By forming the perovskite active layer 3 by means of the present invention, a perovskite active layer with high crystallinity can be obtained.

[0080] According to the present invention, the method further includes the step of forming electrodes. Preferably, the method includes the steps of forming an anode on the transparent conductive layer 2 and forming a cathode on the electron transport layer 5. The electrodes can be formed, for example, by vapor deposition.

[0081] The present invention will be described in detail below through examples. In the following examples, the micro / nano cavity structure templates, chemical reagents, etc., used are all commercially available. Specifically, the chemical reagents CH3NH3I and PbI2 constituting the perovskite active layer were purchased from Xi'an Baolai Optoelectronic Technology Co., Ltd.

[0082] Example 1

[0083] This embodiment illustrates the fabrication method of the perovskite solar cell of the present invention.

[0084] (1) ITO conductive glass was selected as the substrate layer 1 and the transparent conductive layer 2. It was ultrasonically cleaned for 15 min in sequence with ultrapure water, acetone, anhydrous ethanol and isopropanol. After cleaning, it was dried with nitrogen and then hydrophilically treated with plasma. 30 mg of nickel oxide was added to 1 mL of ultrapure water to prepare a solution. The solution was then filtered through a 0.22 μm aqueous filter and spin-coated onto the treated ITO glass substrate at 1000 rpm for 5 s and then at 4000 rpm for 30 s. The solution was then heated and annealed at 120 °C for 20 min to form hole transport layer 3 (thickness of 30 nm).

[0085] (2) Weigh equimolar amounts of PbI2 and MAI, dissolve them in a mixed solution of DMF (N,N-dimethylformamide):DMSO (dimethyl sulfoxide) = 4:1, and stir magnetically overnight to prepare a perovskite precursor solution CH3NH3PbI3. Take 40 mL of this precursor solution and spin-coat it onto nickel oxide using a one-step method (5000 r, 30 s). In the last 20 s, add 120 mL of chlorobenzene antisolvent to rapidly crystallize the perovskite. Using a rectangular micro-nano cavity structure 4-1 with a long side of 20 μm, θ = 60°, an area ratio of 50%, and a fold length of 5 μm (e.g., Figure 2 As shown, a micro-nano cavity structure was imprinted on the perovskite surface with an imprinting depth of 80 nm. Then, the perovskite was annealed at 100 °C for 30 min to obtain a high-quality perovskite film, thereby obtaining a perovskite active layer 4 with a micro-nano cavity structure 4-1 (the thickness of the perovskite active layer 4 is 350 nm).

[0086] (3) The prepared PC61BM solution (20 mg / mL, solvent: chlorobenzene) was coated onto the perovskite active layer 4 and operated at 1000 rpm for 40 s to form the electron transport layer 5 (thickness: 50 nm). The prepared BCP solution (0.5 mg / mL, solvent: anhydrous isopropanol) was spin-coated onto the electron transport layer 5 and operated at 5000 rpm for 60 s to form the hole blocking layer 6 (thickness: 5 nm). A transparent electrode was wiped off, and Ag was selectively evaporated onto the prepared hole blocking layer 6 using a thermal evaporation process to a thickness of less than 10 nm. Evaporation rate, and after the thickness exceeds 10nm, use The perovskite solar cell was fabricated by evaporation at a rate of 100 nm, stopping after 100 nm. A metal electrode layer 7 was prepared as the cathode, and metal 8, deposited on the transparent electrode, was used as the anode.

[0087] Example 2

[0088] This embodiment illustrates the impact of micro / nano recessed structures at different angles on the performance of perovskite solar cells.

[0089] Perovskite solar cells were prepared using the same method as in Example 1, except that the micro-nano recess structure formed in step (2) was different. Specifically, the micro-nano recess structure was formed by nanoimprinting a silicon template with θ values ​​of 50°, 60°, 90°, 110°, and 120° (with other parameters the same as in Example 1) onto the perovskite surface, thereby obtaining a perovskite active layer 4 with a micro-nano recess structure 4-1. The remaining steps were the same as in Example 1, thus obtaining a perovskite solar cell.

[0090] Example 3

[0091] This embodiment illustrates the impact of micro / nano cavity structures of different sizes on the performance of perovskite solar cells.

[0092] Perovskite solar cells were prepared using the same method as in Example 1, except that the micro-nano recess structure formed in step (2) was different. Specifically, the micro-nano recess structure 4-1 was formed by nanoimprinting a silicon template (with the long side of the rectangular micro-nano recess structure 4-1 being 50 μm, and the other parameters being the same as in Example 1) onto the perovskite surface, thereby obtaining a perovskite active layer 4 with the micro-nano recess structure 4-1. The remaining steps were the same as in Example 1, thus obtaining a perovskite solar cell.

[0093] Example 4

[0094] This example illustrates the impact of different perovskite active layers on the performance of perovskite solar cells.

[0095] Perovskite solar cells were prepared using the same method as in Example 1, except that the perovskite precursor solution used in step (2) was different. Specifically, the CH3NH3PbCI3 perovskite precursor solution was prepared by mixing CH3NH3CI and PbCI2 in an equimolar ratio. 40 μL of this precursor solution was spin-coated onto nickel oxide using a one-step method (5000 r, 30 s). In the last 25 seconds, 120 μL of toluene was added dropwise to rapidly crystallize the perovskite. A micro-nano cavity structure was then nanoimprinted onto the perovskite surface using a silicon template, with an imprinting depth of 80 nm. The perovskite was then annealed at 100 °C for 30 min to obtain a high-quality perovskite film, thus obtaining the perovskite active layer 4 with the micro-nano cavity structure 4-1. The remaining steps were the same as in Example 1, thereby obtaining the perovskite solar cell.

[0096] Example 5

[0097] This embodiment illustrates the impact of micro / nano cavity structures at different angles and depths on the performance of perovskite solar cells.

[0098] Perovskite solar cells were prepared using the same method as in Example 1, except that in step (2), the nanoimprinting angle was 60° and the imprinting depth was 40 nm, thereby obtaining a perovskite active layer 4 with a micro-nano cavity structure 4-1. The remaining steps were the same as in Example 1, thereby obtaining a perovskite solar cell.

[0099] Example 6

[0100] This embodiment illustrates the impact of deep micro / nano cavity structures on the performance of perovskite solar cells.

[0101] Perovskite solar cells were prepared using the same method as in Example 1, except that in step (2), the nanoimprint angle was 60° and the imprint depth was 60 nm. The perovskite was then annealed at 100°C for 30 min to obtain a high-quality perovskite film, thus producing a perovskite active layer 4 with a micro / nano cavity structure 4-1. The remaining steps were the same as in Example 1, thereby obtaining the perovskite solar cell.

[0102] Example 7

[0103] This embodiment illustrates the impact of micro / nano cavity structures with different materials and imprinting depths on the performance of perovskite solar cells.

[0104] Perovskite solar cells were prepared using the same method as in Example 1, except that the perovskite precursor solution and the micro / nano-cavity structure used in step (2) were different. Specifically, the CH3NH3PbCI3 perovskite precursor solution was prepared by mixing CH3NH3CI and PbCI2 in an equimolar ratio. 40 μL of this precursor solution was spin-coated onto nickel oxide using a one-step method (5000 r, 30 s). In the last 25 seconds, 120 μL of toluene was added dropwise to rapidly crystallize the perovskite. A micro / nano-cavity structure was then nanoimprinted onto the perovskite surface using a silicon template with θ = 60° (other parameters are the same as in Example 1), with an imprinting depth of 160 nm. The perovskite was then annealed at 100°C for 30 min to obtain a high-quality perovskite film, thus obtaining the perovskite active layer 4 with the micro / nano-cavity structure 4-1. The remaining steps were the same as in Example 1, thereby obtaining the perovskite solar cell.

[0105] Comparative Example 1

[0106] Perovskite solar cells were prepared using the same method as in Example 1, except that the micro-nano recesses formed on the silicon template were all rectangular (the final micro-nano recesses did not have serrated sidewalls).

[0107] Comparative Example 2

[0108] Perovskite solar cells were prepared using the same method as in Example 1, except that the micro-nano recesses formed on the silicon template were all equilateral triangles (the final micro-nano recesses did not have serrated sidewalls).

[0109] Test case

[0110] Optical photographs of the perovskite active layer in Example 1 were taken using an optical microscope, and the results are as follows: Figure 3 As shown.

[0111] SEM images of the perovskite active layer in Example 1 were taken using a scanning electron microscope (JEOL, JSM-7500F, Japan). The results are as follows. Figure 4 As shown. By Figure 4 It is evident that the imprinted area contains no voids, while the non-imprinted area contains numerous pores; this difference is due to pressure confinement. Therefore, this invention, through nanoimprinting, can reduce the defect density of the perovskite active layer, and combined with the micro / nano cavity structure, increases the light propagation path within the perovskite active layer, thereby significantly improving the performance of solar cells.

[0112] The XRD pattern of the perovskite active layer in Example 1 was determined using an X-ray diffractometer (D / max 2500, Rigaku, Japan). The results are as follows: Figure 5 As shown.

[0113] The absorption and reflectance spectra of perovskite solar cells were measured, and the results are as follows: Figure 6 and Figure 7 As shown. By Figure 6 and Figure 7 It can be seen that the micro-nano cavity structure with a zigzag angle θ = 60° can achieve higher absorption with the lowest reflection.

[0114] A control perovskite solar cell without forming a micro / nano cavity structure 4-1 was prepared according to the method of Example 1 (i.e., without the nanoimprinting step), and the light-harvesting efficiency spectra of the control perovskite solar cell and the perovskite solar cell of Example 1 were measured. The results are as follows: Figure 8 As shown. By Figure 8 It is known that the light enrichment efficiency of perovskite solar cells can be improved by forming the micro-nano cavity structure of the present invention.

[0115] The perovskite solar cells described above and the perovskite solar cells in Example 1 with 60° sawtooth-shaped micro-nano cavity structures were simulated using FDTD software to obtain their localized optical simulation diagrams. Figure 9 The left image shows a control perovskite solar cell, and the right image shows a perovskite solar cell of Example 1. Figure 9 The results demonstrate that the micro-nano cavity structure with θ = 60° can effectively realize the incident light localization in the perovskite active layer.

[0116] Figure 10-12 The images show the IV curves of perovskite solar cells from Example 1, Comparative Example 1, and Comparative Example 2, respectively.

[0117] The specific parameters of the perovskite solar cell in Example 1 are as follows: short-circuit current density 23.31 mA / cm². 2 The open-circuit voltage is 1.085V, the fill factor is 75.15%, and the photoelectric conversion efficiency is 19.01%.

[0118] The specific parameters of the perovskite solar cell in Comparative Example 1 are as follows: short-circuit current density 22.31 mA / cm². 2 The open-circuit voltage is 1.083V, the fill factor is 74.78%, and the photoelectric conversion efficiency is 18.07%.

[0119] The specific parameters of the perovskite solar cell in Comparative Example 2 are as follows: short-circuit current density 21.99 mA / cm². 2 The open-circuit voltage is 1.074V, the fill factor is 73.89%, and the photoelectric conversion efficiency is 17.45%.

[0120] As can be seen from the comparison of Example 1 and Comparative Examples 1-2 above, the perovskite solar cell of the present invention can further improve its various performances by forming a micro-nano cavity structure with serrated sidewalls.

[0121] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A perovskite solar cell, characterized by, The perovskite solar cell includes a perovskite active layer (4). Among them, a micro-nano cavity structure (4-1) is formed on the perovskite active layer (4), and at least a portion of the sidewall of the micro-nano cavity structure (4-1) is a serrated sidewall. The zigzag sidewall has a bend angle of 50°-70°; the zigzag sidewall has a uniformly distributed bend angle; the micro-nano cavity structure (4-1) has a size of 10nm-100μm and a depth of 50-150nm; the zigzag length of the zigzag sidewall is 1μm-5μm.

2. The perovskite solar cell according to claim 1, wherein, The area of ​​the micro-nano cavity structure (4-1) accounts for 40-60% of the area of ​​the surface of the perovskite active layer (4).

3. The perovskite solar cell according to claim 1, wherein, The micro-nano cavity structure (4-1) is formed into a micro-nano cavity array structure.

4. The perovskite solar cell according to any one of claims 1-3, wherein, The perovskite solar cell comprises a substrate layer (1), a transparent conductive layer (2), a hole transport layer (3), a perovskite active layer (4), an electron transport layer (5), and a hole blocking layer (6) stacked sequentially, as well as electrodes.

5. The perovskite solar cell according to claim 4, wherein, The perovskite active layer (4) has a micro-nano cavity structure (4-1) formed on its surface away from the base layer (1).

6. The perovskite solar cell according to claim 4, wherein, The base layer (1) is a rigid base or a flexible base.

7. The perovskite solar cell according to claim 6, wherein, The substrate layer (1) is one or more of ITO conductive glass, FTO conductive glass, PEN film, PET film, aluminum foil, and copper foil.

8. The perovskite solar cell according to claim 4, wherein, The material of the hole transport layer (3) is one or more of PEDOT:PSS, Spiro-OMeTAD, PTAA, NiO x .

9. The perovskite solar cell according to claim 8, wherein, The material of the hole transport layer (3) is NiO x .

10. The perovskite solar cell according to claim 4, wherein, The material of the perovskite active layer (4) is one or more of CH3NH3PbI3, CH3NH3PbBr3, CH3NH3PbCl3, CsPbI3, FAPbI3, CsSnI3, CsPbBr3, CsPbCl3, CH3NH3PbBr2I, and CH3NH3PbBrI2.

11. The perovskite solar cell according to claim 4, wherein, The electron transport layer is made of one or more of TiO2, SnO2, PC61BM, PC71BM, and C60.

12. A method for preparing a perovskite solar cell according to any one of claims 1-11, characterized in that, The method includes forming a micro-nano cavity structure (4-1) on the surface of the perovskite active layer (4) during the process of forming a perovskite active layer (4) using a perovskite precursor. Among them, at least a portion of the sidewall of the micro-nano cavity structure (4-1) is a serrated sidewall.

13. The preparation method according to claim 12, wherein, The method includes: (1) A hole transport layer (3) is prepared on a substrate (1) and a transparent conductive layer (2) using a hole transport material; (2) A perovskite active layer (4) is formed on the hole transport layer (3) using a perovskite precursor, and a micro-nano cavity structure (4-1) is formed on the surface of the perovskite active layer (4). (3) An electron transport layer is formed on the perovskite active layer (4) using an electron transport material.

14. The preparation method according to claim 12, wherein, Micro-nano cavity structures (4-1) are formed on the surface of the perovskite active layer (4) by one or more of the following methods: nanoimprinting, laser etching, plasma treatment, ion beam etching, and magnetron sputtering.

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