Preparation method of perovskite film with mortise and tenon structure and application thereof in solar cell

Abstract

This invention provides a method for preparing a perovskite thin film with a mortise and tenon structure and its application in solar cells. The method is simple to operate and has good repeatability. Solar cells prepared based on the mortise and tenon structure of the perovskite thin film have a mortise and tenon structure at the interface between the perovskite layer and the charge transport layer, which increases the contact area between the charge transport layer and the perovskite, improving the charge carrier extraction efficiency. This effectively increases the charge extraction density in the perovskite solar cell, achieving a perovskite solar cell with high carrier transport rate, ultimately achieving a photoelectric conversion efficiency of up to 24.5%. Furthermore, based on this mortise and tenon structure, hydrophobic materials can be vertically inserted at the perovskite grain boundaries, protecting the perovskite solar cell from damage caused by external moisture intrusion, thus effectively improving the long-term stability of the perovskite solar cell. Its T95 stability (maintaining more than 95% of the initial efficiency) can reach up to 5000 hours. The perovskite thin film with a mortise and tenon structure obtained by the preparation method provided by this invention is expected to be widely used in the field of high-efficiency perovskite solar cells.

Description

[0001] This invention relates to a method for preparing perovskite thin films based on mortise and tenon structures and their application in solar cells. Background Technology

[0002] The development of clean energy is the foundation for a low-carbon economy and sustainable development in the future, and developing low-cost, high-performance photoelectric conversion technology is one of the keys to achieving this goal. Metal halide perovskites combine the advantages of both organic and inorganic materials in photoelectric properties, solvent processing, and low-temperature handling, demonstrating enormous application potential in the optoelectronic field. In 2013, *Science* magazine selected perovskite solar cells as one of the top ten scientific breakthroughs of the year. After just a few years of development, the device efficiency of perovskite solar cells has exceeded 25.5%, becoming a new type of photovoltaic system that promises to further reduce the price of photovoltaic power generation. Traditional perovskite solar cell device structures are divided into mesoporous and planar types; however, regardless of the device structure, there is an imbalance in charge extraction capabilities between the electron transport layer and the hole transport layer. Currently, the best-performing perovskite solar cells are still based on traditional planar structures, using spiro-OMeTAD (2,2′,7,7′-tetratetra(N,Np-dimethoxyphenylamino)-9,9′-spirodifluorene) (μh = 5 × 10⁻⁵ cm²V⁻¹s⁻¹) as the hole transport layer and tin dioxide (SnO₂, μe = 240 cm²V⁻¹s⁻¹) as the electron transport layer. Their extraction capabilities differ greatly, which is one of the main problems limiting perovskite solar cells from reaching the Shockley-Quiet limit (SQ limit, the theoretical energy conversion limit achievable by a single pn-junction solar cell).

[0003] Nature, 2021, Vol. 598, pp. 444-450: A strategy to reduce electron extraction and match hole extraction by inserting a suppression layer between SnO2 and the perovskite layer is reported. However, the absolute loss in total carrier density extraction limits its potential to achieve the SQ limit. Therefore, achieving balanced carrier transport in perovskite solar cells is crucial for realizing high-efficiency perovskite solar cells. Summary of the Invention

[0004] To address the above technical problems, this invention provides a method for preparing a perovskite thin film with a mortise and tenon structure. The preparation process is simple, the film formation is good, and the repeatability is high. It can effectively improve the carrier extraction density in perovskite solar cells while enhancing resistance to moisture. Therefore, this method exhibits high photoelectric conversion efficiency in the preparation of perovskite solar cell devices with a mortise and tenon structure.

[0005] The technical problem to be solved by this invention is to provide a method for preparing perovskite thin films based on a mortise and tenon structure, which has good film-forming properties, high repeatability, and can effectively balance carrier transport in perovskite solar cells to obtain solar cells with high photoelectric conversion efficiency. The method is characterized by:

[0006] 1. A method for preparing a perovskite thin film based on a mortise and tenon structure, characterized in that the preparation method is as follows:

[0007] (1) On a transparent substrate with a conductive layer, an electron transport layer material or a hole transport layer material is coated to obtain an electron transport layer or a hole transport layer.

[0008] (2) Coat the surface of the electron transport layer or hole transport layer obtained in step (1) with ABX3 perovskite solution doped with self-crosslinking organic material, and perform annealing treatment to obtain a perovskite film. After annealing, the organic material is self-crosslinked and exists at the grain boundaries of the perovskite film.

[0009] (3) Coat the surface of the perovskite film obtained in step (2) with an organic electron transport layer or an organic hole transport layer material solution. The solvent in the solution can dissolve the self-crosslinking organic material at the grain boundary of the perovskite film. The organic electron transport layer or organic hole transport layer material penetrates into the grain boundary of the perovskite film to form a perovskite film with a tenon and mortise structure.

[0010] 2. The transparent substrate of the conductive layer includes any one or more of the following: glass substrate, FTO glass substrate, ITO glass substrate, PEN substrate or PET substrate;

[0011] 3. The electron transport layer material includes any one or more of the following: doped or undoped inorganic electron transport layer materials (such as TiO2, SnO2, ZnO, Zn2SnO4, Cs2CO3, BaTiO3, SrTiO3, MgTiO3, BaSnO3, or CdS) and doped or undoped organic electron transport layer materials (such as fullerenes and their derivatives, non-fullerene electron transport materials); the hole transport layer material includes any one or more of the following: doped or undoped organic hole transport materials (such as aniline, carbazole, phthalocyanine, phenothiazine, phenoxazine, or thiophene materials, etc.) and doped or undoped inorganic hole transport materials (such as NiO, Cu2O, PbS, V2O5, MoO3, CuSCN, Cu1, etc.).

[0012] 4. The perovskite layer material is of type ABX3, where A includes any one or more of potassium ions (K+), cesium ions (Cs+), methylamine ions (CH3NH3+), and formamidinium ions (NH2CH=NH2+); B includes any one or more of lead ions (Pb2+), tin ions (Sn2+), and germanium ions (Ge2+); and X includes any one or more of iodide ions (I-), bromide ions (Br-), chloride ions (Cl-), and fluoride ions (F-).

[0013] 5. Among them, self-crosslinking organic molecular materials include, but are not limited to, molecules containing one or more functional groups from N-vinyl-2-pyrrolidone, N,N-dimethylformamide, and diallyl sulfoxide, which simultaneously contain alkenyl functional groups and pyrrolidone, amide, or sulfoxide derivatives;

[0014] 6. The solvent used in the organic electron transport layer or organic hole transport layer material solution is a benzene-based or ester-based solvent that does not dissolve the underlying perovskite film, including any one or more of chlorobenzene, toluene, xylene, benzene, dichlorobenzene, ethyl acetate, butyl acetate, isopropanol, and n-butanol;

[0015] 7. The perovskite thin film with mortise and tenon structure is used to prepare perovskite solar cells.

[0016] The present invention has the following beneficial effects:

[0017] 1) This invention provides a method for preparing a perovskite thin film with a mortise and tenon structure. The perovskite thin film prepared by the method has a mortise and tenon structure. The preparation method is simple and highly reproducible. It only requires adding a self-crosslinkable organic material to the perovskite precursor solution and preparing it through a multi-step spin coating process. It can be achieved in a general laboratory.

[0018] 2) This invention provides a method for preparing a perovskite thin film with a mortise and tenon structure. The perovskite thin film prepared by the method can be applied to solar cells to effectively balance carrier extraction in the device, thereby obtaining a high-efficiency perovskite photovoltaic device. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with examples of the invention to explain the invention and do not constitute a limitation thereof.

[0020] Figure 1 A schematic diagram of the preparation method of perovskite thin films with mortise and tenon structure;

[0021] Figure 2Cross-sectional STEM images of ultrathin perovskite slices (<100 nm thickness) fabricated by FIB show the perovskite structure with mortise and tenon joints.

[0022] Figure 3 Current-voltage curves of perovskite solar cell devices based on mortise and tenon structures;

[0023] Figure 4 Stability of perovskite solar cell devices based on mortise and tenon structure. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the terms "comprising" or "including" as used throughout this specification and claims are open-ended and should be interpreted as "comprising but not limited to". The specific embodiments described herein are merely illustrative of the invention and are not intended to limit it. The scope of protection of this invention is determined by the appended claims.

[0025] Example 1: Method for preparing perovskite thin films with mortise and tenon joints

[0026] The preparation method is as follows:

[0027] The specific preparation steps of the perovskite thin film with the mortise and tenon structure described in this invention are as follows:

[0028] 1) Cleaning: First, use detergent to clean the dust and other contaminants adhering to the surface of the FTO glass substrate. Then, use 15mL of 1% surfactant solution, water and ethanol to sonicate to remove organic contaminants. Dry the cleaned ITO glass substrate with nitrogen gas to obtain a clean transparent conductive substrate required for the experiment. Then, treat it with ultraviolet light and ozone for 30 minutes to ensure that its surface is clean.

[0029] 2) Preparation of the electron transport layer: Tin dioxide was deposited using a chemical bath method. 160 μL of mercaptoacetic acid, 2.5 mL of HCl (37 wt%), 2.5 g of urea, and 0.55 g of SnCl₂·2H₂O were dissolved in 200 mL of ice-cold pure water and shaken well. This solution was diluted 5 times, and the cleaned FTO was immersed in the solution. After heating in a 90°C oven for 3.5 h, the substrate was removed, sonicated with pure water for 5 minutes, then sonicated with IPA for 5 minutes, dried, and annealed in air at 170°C for 1 hour to prepare the SnO₂ layer.

[0030] 3) Preparation of hole transport layer: Weigh 73 mg of Spiro-OMeTAD powder, add 1 ml of chlorobenzene, then add 18 μl of Li-TFSI (520 mg / ml dissolved in acetonitrile), 29 μl of FK209 (300 mg / ml dissolved in acetonitrile) and 30 μl of 4-tert-butylpyridine, and stir for 1 h to dissolve completely.

[0031] 4) Preparation of the mortise-and-tenon perovskite layer: A 1.5 mol / L perovskite precursor solution of methylamine lead bromide (FAPbl3) 0.95 (MAPbBr3) 0.05 was prepared by mixing FAI, Pb12, MACl, MABr, and PbBr2 in DMF / DMSO (8:1 v / v). This solution was then spin-coated onto the electron transport layer at a speed of 1000 rpm for 10 s, followed by 5000 rpm for 60 s. Ethyl acetate was added dropwise as an antisolvent during the final 10 s of spin-coating. The substrate was then annealed at 100°C for 1 hour to obtain the perovskite film. After cooling to room temperature, the hole transport layer solution was dropwise added onto the perovskite film and spin-coated at 3000 rpm for 30 seconds to obtain the mortise-and-tenon perovskite film with a hole transport layer covering its surface.

[0032] Example 2: Perovskite Solar Cell Based on Mortise and Tenon Structure Perovskite Thin Film

[0033] The perovskite thin film with the mortise and tenon structure described in Example 1 was used to fabricate a formal perovskite photovoltaic cell device of type electron transport layer (n) - photoactive layer (i) - hole transport layer (p). The device structure is: FTO / tin dioxide (SnO2) / perovskite layer (FAPbl3)0.95 (MAPbBr3)0.05 / hole transport layer (Spiro-OMeTAD) / Au. The FTO glass substrate consists of a glass substrate and fluorine-doped tin oxide. Tin dioxide serves as the electron transport layer, the mortise and tenon structured perovskite layer serves as the light-absorbing layer, Spiro-OMeTAD serves as the hole transport layer, and gold serves as the metal electrode.

[0034] The fabrication steps of the perovskite solar cell device are as follows:

[0035] 1) The preparation methods for the cleaning, electron transport layer, perovskite layer with mortise and tenon structure and hole transport layer are as shown in Example 1.

[0036] 2) Place it in a vacuum evaporation chamber and deposit the metal electrode onto the surface of the hole transport layer by vacuum evaporation to obtain a perovskite solar cell device with a mortise and tenon structure.

[0037] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements without departing from the principles of the present invention, and these improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a perovskite thin film based on a dovetail structure, characterized by, The preparation method is as follows: (1) On a transparent substrate with a conductive layer, an electron transport layer material or a hole transport layer material is coated to obtain an electron transport layer or a hole transport layer. (2) Coat the surface of the electron transport layer or hole transport layer obtained in step (1) with ABX3 perovskite solution doped with self-crosslinking organic molecular material, and perform annealing treatment to obtain a perovskite film. After annealing, the organic material is self-crosslinked and exists at the grain boundaries of the perovskite film. (3) Coat the surface of the perovskite film obtained in step (2) with an organic electron transport layer or organic hole transport layer material solution. The solvent in the solution can dissolve the self-crosslinked organic molecular material at the grain boundary of the perovskite film. The organic electron transport layer or organic hole transport layer material penetrates into the grain boundary of the perovskite film to form a perovskite film with a tenon and mortise structure. The self-crosslinking organic molecular materials include N-vinyl-2-pyrrolidone, N,N-dimethylformamide, and diallyl sulfoxide; The solvent used in the organic electron transport layer or organic hole transport layer material solution is a benzene-based or ester-based solvent that does not dissolve the underlying perovskite film, including one or more of chlorobenzene, toluene, xylene, benzene, dichlorobenzene, ethyl acetate, butyl acetate, isopropanol, and n-butanol.

2. The production method according to claim 1, characterized by, The transparent substrate with a conductive layer includes any one or more of the following: FTO glass substrate, ITO glass substrate, PEN substrate, or PET substrate.

3. The preparation method according to claim 1, characterized in that, The electron transport layer material includes any one or more of doped or undoped inorganic electron transport layer materials and doped or undoped organic electron transport layer materials; the hole transport layer material includes doped or undoped organic hole transport materials and doped or undoped inorganic hole transport materials. The inorganic electron transport layer material includes one or more of TiO2, SnO2, ZnO, Zn2SnO4, Cs2CO3, BaTiO3, SrTiO3, MgTiO3, BaSnO3, or CdS; The organic electron transport layer material includes fullerenes and their derivatives and / or non-fullerene electron transport materials. The organic hole transport material includes one or more of the following: aniline, carbazole, phthalocyanine, phenothiazine, phenotoxazine, or thiophene materials; The inorganic hole transport material includes one or more of NiO, Cu2O, PbS, V2O5, MoO3, CuSCN, and Cu1.

4. The preparation method according to claim 1, characterized in that, In ABX3 perovskite, A includes formamidinium ions (NH2CH=NH2). + ), methylamine ions (CH3NH3) + ), cesium ions (Cs) + ), rubidium ions (Rb + ), potassium ions (K) + ), ammonium ions (NH4) + One or more of the following; B includes lead ions (Pb). 2+ ), tin ions (Sn) 2+ germanium ions (Ge) 2+ One or more of the following: X includes iodide ions (I0). - ), bromide ions (Br) - ), chloride ions (Cl) - ) and fluoride ions (F - One or more of them.

5. A perovskite solar cell is prepared by preparing a perovskite thin film with a mortise and tenon structure using the method described in claim 1.

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