Fe2O3 nanorod array perovskite solar cell and preparation method thereof

Abstract

The invention relates to the field of photovoltaic power generation, and mainly relates to a Fe2O3 nanorod array perovskite solar cell and a preparation method thereof. The preparation method of the Fe2O3 nanorod array perovskite solar cell is provided for solving the problems that in the prior art, a physical coating technology is complex in process, high in cost and low in production efficiency. A Nb-TiO2 compact layer is prepared through a hydrolysis-pyrolysis method, a Fe2O3 nano array is prepared through a hydrothermal method, a CH3NH3PbI3-xBrx thin film is prepared through a continuous two-step deposition method, a hole transport layer is prepared through a deposition method, and the Fe2O3 nano rod array perovskite solar cell is prepared. The method is simple and environment-friendly in process, low in cost and high in production efficiency.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation, and mainly to a Fe2O3 nanorod array perovskite solar cell and its preparation method. Background Technology

[0002] Perovskite solar cells have attracted widespread attention and extensive research since their initial report in 2009 due to their numerous advantages, including simple structure, easily tunable bandgap, high absorption coefficient, and low fabrication cost. Their photoelectric conversion efficiency has increased from an initial 3.8% to the current 25%, approaching that of silicon-based solar cells, demonstrating promising application prospects. The electron transport layer of perovskite solar cells typically employs planar, mesoporous, or one-dimensional array structures. Among these, the one-dimensional array structure boasts a higher specific surface area and more direct radial electron transport. Compared to planar structures, the higher specific surface area of ​​the one-dimensional array structure effectively increases the contact area with the perovskite material, facilitating carrier transport and separation. Compared to mesoporous structures, the one-dimensional array structure provides a more direct and ordered radial transport channel for electrons, enhancing electron injection from the perovskite material to the electron transport material, thereby improving the photovoltaic performance of the corresponding perovskite solar cell.

[0003] Chinese patent application CN201510100147.2 discloses a method for preparing a quasi-one-dimensional TiO2 nanostructure array framework layer for perovskite solar cells. First, a dense TiO2 layer and a Ti metal thin film are sequentially prepared on a conductive glass substrate using physical deposition techniques such as magnetron sputtering, vacuum thermal evaporation, and pulsed laser deposition. Then, the Ti metal thin film is oxidized into a quasi-one-dimensional TiO2 nanostructure array as the framework layer for the perovskite solar cell using a solution oxidation method. A perovskite-type organometal halide light-absorbing layer, a hole transport layer, and a counter electrode are then prepared on the framework layer to obtain the perovskite solar cell. The quasi-one-dimensional TiO2 nanostructure array framework layer prepared by this method can improve carrier transport velocity, reduce carrier recombination probability, and thus improve the carrier collection efficiency and photoelectric conversion efficiency of the perovskite solar cell. However, these physical deposition techniques are complex, costly, and have low production efficiency. Summary of the Invention

[0004] In order to overcome the problems of complex process, high cost and low production efficiency of physical coating technology in the prior art, the present invention provides an environmentally friendly fire-resistant power cable. Through optimization of materials and structure, it has excellent flame retardant properties and reduces costs.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a Fe2O3 nanorod array perovskite solar cell, comprising the following steps: (1) Etching and cleaning of conductive substrate; (2) Preparation of Nb-TiO2 dense layer: A solution of niobium pentachloride and isopropyl titanate in acidic isopropanol was coated on the conductive substrate prepared in step (1), placed in a closed hydrothermal reactor and deionized water was added. The mixture was heated to 160-200℃ and held for 4-12 hours to obtain a preliminary compound. Then, under a nitrogen atmosphere, a reflux reaction was carried out and the mixture was held at 300-600℃ for 2-6 hours to form a dense layered structure of Nb-TiO2. (3) Preparation of Fe2O3 nanoarray: A solution of ferric nitrate and isopropyl titanate in acidic isopropanol was coated on the Nb-TiO2 dense layer prepared in step (2), placed in a sealed hydrothermal reactor and deionized water was added. The mixture was heated to 120-200℃ and kept for 4-12 hours. (4) Preparation of CH3NH3PbI3-xBrx thin film: CH3NH3PbI3-xBrx perovskite thin film with a molar ratio of CH3NH3I:CH3NH3Br=85:15 was prepared on Fe2O3 nanoarray by a two-step continuous deposition method; (5) Preparation of hole transport layer: A spiro-OMeTAD solution is coated on the Nb-TiO2 dense layer and CH3NH3PbI3-xBrx thin film prepared in steps (1) to (4) to form a hole transport layer.

[0006] Preferably, step (1) specifically includes: etching the conductive substrate according to the pattern required for the perovskite solar cell structure using zinc powder and 1-6 mol / L hydrochloric acid, followed by ultrasonic cleaning and nitrogen drying for later use.

[0007] Preferably, in step (1), the conductive substrate is any one of ITO, FTO, and AZO.

[0008] More preferably, in step (1), the conductive substrate is FTO.

[0009] In step (2), the preparation of the Nb-TiO2 dense layer employs a combination of hydrothermal reaction and reflux reaction. During the hydrothermal synthesis process, the precursor used can be fully dissolved under hydrothermal conditions and reacted uniformly under high temperature and pressure, ultimately forming a high-purity and uniform Nb-TiO2 layer. Furthermore, the reflux reaction is carried out in an inert atmosphere, which can effectively improve the thermal stability of the Nb-TiO2 layer, prevent oxidation or phase transformation of the material, and enhance its reliability under high-temperature conditions. The uniform and stable laminated structure of the Nb-TiO2 dense layer is not only beneficial to electrical conductivity but also exhibits excellent performance in optoelectronic applications.

[0010] Preferably, in step (2), the molar ratio of niobium pentachloride to isopropyl titanate is (3-7):1.

[0011] Preferably, in step (3), the molar ratio of ferric nitrate to isopropyl titanate is (3-7):1.

[0012] In step (3), under hydrothermal conditions, the iron ions in ferric nitrate react with the oxygen source and hydroxide ions to form an Fe2O3 nanoarray. This invention uses a hydrothermal method to prepare Fe2O3 nanoarrays, which significantly reduces preparation time compared to traditional iron oxide preparation methods.

[0013] Although Fe2O3 is grown in nanorod arrays with different lengths, diameters, and field densities via hydrothermal deposition, it remains suitable as a framework layer for perovskite solar cells due to its high specific surface area and excellent electrical conductivity and electron mobility, for the following reasons: ①Fe2O3 has excellent optical properties and can effectively absorb visible and near-infrared light. As the framework layer in perovskite solar cells, its optical transmittance and scattering properties can work together with the perovskite layer to improve photoelectric conversion efficiency. ②Fe2O3 has a suitable band structure, which can provide good conductivity for electron migration; the nanorod array structure helps to improve the electron conduction efficiency, making the collection and transport of photogenerated carriers in perovskite solar cells more efficient; ③ The Fe2O3 nanorod array has a high specific surface area, which can increase the contact area with the perovskite layer. This helps to improve the carrier capture efficiency and the rate of interfacial reaction, thereby effectively converting more light energy.

[0014] In step (4), the preparation of the CH3NH3PbI3-xBrx thin film employs a two-step continuous deposition method, specifically involving solution deposition on a Fe2O3 nanoarray at a molar ratio of CH3NH3I:CH3NH3Br = 85:15. This two-step deposition method allows for the formation of a relatively thin CH3NH3PbI3 layer in the first step, followed by doping with CH3NH3Br in the second step. This reduces defects in the film and improves its crystallinity and uniformity. By adjusting the molar ratio of CH3NH3I and CH3NH3Br, this method allows for flexible control of the film's composition and properties, resulting in films with optical and electrical properties suitable for specific applications. Br doping reduces the band gap, leading to better performance in light absorption and photoelectric conversion efficiency. Furthermore, appropriate doping can improve carrier mobility and enhance the overall performance of the device. Using a two-step deposition method promotes more uniform nucleation and growth, enhances the structural stability of the film, and reduces the degradation rate under illumination conditions, thereby improving its stability in practical applications.

[0015] Preferably, step (4) specifically includes the following steps: methyl iodide (CH3NH3I) and lead iodide (H) are mixed and dissolved in a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to form a CH3NH3PbI3 perovskite precursor solution. Then, the CH3NH3PbI3 perovskite precursor solution is coated onto the Fe2O3 nanoarray prepared in step (3). The CH3NH3PbI3 perovskite film is placed on a hot stage and annealed sequentially in an air atmosphere for 25-40 min, in a mixed hot steam containing air (DMSO, HBr, and H2O) for 3-8 min, in a hot steam containing air (DMSO) for 10 min, and in a mixed hot steam containing air (CH3NH2 and H2O) for 5-8 min. The hot stage temperature is always maintained at 100°C. The CH3NH3PbI3-xBrx film is prepared by cleaning and combining a multi-step atmosphere annealing process.

[0016] In step (5), the hole transport layer was prepared by spin-coating a spiro-OMeTAD solution onto a substrate treated with an Nb-TiO2 dense layer and a CH3NH3PbI3-xBrx thin film. The interface between spiro-OMeTAD and the CH3NH3PbI3-xBrx thin film was good, which helped improve the carrier transport efficiency. Simultaneously, the presence of the Nb-TiO2 dense layer effectively reduced interface defects, improving the stability and efficiency of the photovoltaic cell. As a highly efficient organic material, spiro-OMeTAD possesses excellent hole transport performance and high conductivity, contributing to improved overall photovoltaic cell performance. The molecular structure of spiro-OMeTAD promotes hole movement through π-π interactions and ionic bonds, enabling photogenerated carriers to be efficiently separated and transported to the corresponding electrodes. Holes are transported in spiro-OMeTAD through transitions, forming effective hole conduction channels. When light irradiates the photoelectric material (such as CH3NH3PbI3-xBrx), electron-hole pairs are generated. At this point, spiro-OMeTAD, acting as a hole transport layer, can effectively guide photogenerated holes to the anode, reducing the possibility of recombination and improving the photoelectric conversion efficiency of the photovoltaic cell.

[0017] Preferably, the CH3NH3PbI3-xBrx film is coated with a spiro-OMeTAD solution and then subjected to heat treatment.

[0018] Heat treatment can increase the degree of crosslinking of spiro-OMeTAD, thereby enhancing the mechanical strength and electrical conductivity of the film. The crosslinking process can also improve the stability of the film, contributing to the reliability of the photovoltaic cell during long-term operation.

[0019] Secondly, the present invention provides a Fe2O3 nanorod array perovskite solar cell prepared by the above preparation method.

[0020] The beneficial effects of this invention are: (1) This invention prepares a dense Nb-TiO2 layer by hydrolysis-pyrolysis, a Fe2O3 nanoarray by hydrothermal method, a CH3NH3PbI3-xBrx thin film by continuous two-step deposition method, and a hole transport layer by deposition method to obtain a Fe2O3 nanorod array perovskite solar cell. The process of this invention is simple, environmentally friendly, low in cost, and high in production efficiency. (2) The Fe2O3 nanorod array perovskite solar cell prepared by this invention also exhibits good performance in optoelectronic applications. Attached Figure Description

[0021] Figure 1 This is a flowchart of the fabrication method for Fe2O3 nanorod array perovskite solar cells. Detailed Implementation

[0022] The technical solution of the present invention will be further described below through specific embodiments.

[0023] In this invention, unless otherwise specified, the raw materials and equipment used can be purchased from the market or are commonly used in the field. The methods in the embodiments, unless otherwise specified, are conventional methods in the field.

[0024] General Implementation Examples A method for preparing a Fe2O3 nanorod array perovskite solar cell, including as follows: Figure 1 The following steps are shown: (1) Etching and cleaning of conductive substrate; (2) Preparation of Nb-TiO2 dense layer: A solution of niobium pentachloride and isopropyl titanate in acidic isopropanol was coated on the conductive substrate prepared in step (1), placed in a closed hydrothermal reactor and deionized water was added. The mixture was heated to 160-200℃ and held for 4-12 hours to obtain a preliminary compound. Then, under a nitrogen atmosphere, a reflux reaction was carried out and the mixture was held at 300-600℃ for 2-6 hours to form a dense layered structure of Nb-TiO2. (3) Preparation of Fe2O3 nanoarray: A solution of ferric nitrate and isopropyl titanate in acidic isopropanol was coated on the Nb-TiO2 dense layer prepared in step (2), placed in a sealed hydrothermal reactor and deionized water was added. The mixture was heated to 120-200℃ and kept for 4-12 hours. (4) Preparation of CH3NH3PbI3-xBrx thin film: CH3NH3PbI3-xBrx perovskite thin film with a molar ratio of CH3NH3I:CH3NH3Br=85:15 was prepared on Fe2O3 nanoarray by a two-step continuous deposition method; (5) Preparation of hole transport layer: A spiro-OMeTAD solution is coated on the Nb-TiO2 dense layer and CH3NH3PbI3-xBrx thin film prepared in steps (1) to (4) to form a hole transport layer.

[0025] Preferably, step (1) specifically includes: etching the conductive substrate according to the pattern required for the perovskite solar cell structure using zinc powder and 1-6 mol / L hydrochloric acid, followed by ultrasonic cleaning and nitrogen drying for later use.

[0026] Preferably, in step (1), the conductive substrate is any one of ITO, FTO, and AZO.

[0027] More preferably, in step (1), the conductive substrate is FTO.

[0028] Preferably, in step (2), the molar ratio of niobium pentachloride to isopropyl titanate is (3-7):1.

[0029] Preferably, in step (3), the molar ratio of ferric nitrate to isopropyl titanate is (3-7):1.

[0030] Preferably, step (4) specifically includes the following steps: methyl iodide (CH3NH3I) and lead iodide (PbI2) are mixed and dissolved in a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to form a CH3NH3PbI3 perovskite precursor solution. Then, the CH3NH3PbI3 perovskite precursor solution is coated onto the Fe2O3 nanoarray prepared in step (3). The CH3NH3PbI3 perovskite film is placed on a hot stage and annealed sequentially in an air atmosphere for 25-40 min, in a mixed hot steam containing air (DMSO, HBr, and H2O) for 3-8 min, in a hot steam containing air (DMSO) for 10 min, and in a mixed hot steam containing air (CH3NH2 and H2O) for 5-8 min. The hot stage temperature is always maintained at 100°C. The CH3NH3PbI3-xBrx film is prepared by cleaning and combining a multi-step atmosphere annealing process.

[0031] Preferably, the CH3NH3PbI3-xBrx film is coated with a spiro-OMeTAD solution and then subjected to heat treatment.

[0032] A perovskite solar cell with Fe2O3 nanorod arrays prepared by the above method.

[0033] Example 1 A perovskite solar cell with Fe2O3 nanorod arrays, the preparation method includes the following steps: (1) Etching and cleaning of conductive substrate: The AZO conductive glass substrate was cut into a rectangle of 20mm×15mm, zinc powder was spread on it, and 2mol / L hydrochloric acid was added for etching. After 10 minutes, the hydrochloric acid was rinsed off with deionized water, and then ultrasonically cleaned and dried with nitrogen gas for later use. (2) Preparation of Nb-TiO2 dense layer: A solution of 3 mol / L niobium pentachloride and 1 mol / L isopropyl titanate in acidic isopropanol was coated on the conductive substrate prepared in step (1), placed in a sealed hydrothermal reactor and deionized water was added. The mixture was heated to 160°C and held for 7 hours to obtain a preliminary compound. Then, under a nitrogen atmosphere, a reflux reaction was carried out and the mixture was held at 300°C for 2 hours to form a dense layered structure of Nb-TiO2. (3) Preparation of Fe2O3 nanoarray: A solution of 5 mol / L ferric nitrate and 1 mol / L isopropyl titanate in acidic isopropanol was coated on the Nb-TiO2 dense layer prepared in step (2), placed in a sealed hydrothermal reactor and deionized water was added. The mixture was heated to 120°C and kept for 12 hours. (4) Preparation of CH3NH3PbI3-xBrx thin film: CH3NH3PbI3-xBrx perovskite thin film with a molar ratio of CH3NH3I:CH3NH3Br=85:15 was prepared on Fe2O3 nanoarray by a two-step continuous deposition method; (5) Preparation of hole transport layer: A spiro-OMeTAD solution is coated on the Nb-TiO2 dense layer and CH3NH3PbI3-xBrx thin film prepared in steps (1) to (4) to form a hole transport layer.

[0034] Example 2 A perovskite solar cell with Fe2O3 nanorod arrays, the preparation method includes the following steps: (1) Etching and cleaning of conductive substrate: The FTO conductive glass substrate was cut into a rectangle of 20mm×15mm, zinc powder was spread on it, and 1mol / L hydrochloric acid was added for etching. After 10 minutes, the hydrochloric acid was rinsed off with deionized water, and then ultrasonically cleaned and dried with nitrogen gas for later use. (2) Preparation of Nb-TiO2 dense layer: A solution of 3 mol / L niobium pentachloride and 1 mol / L isopropyl titanate in acidic isopropanol was coated on the conductive substrate prepared in step (1), placed in a sealed hydrothermal reactor and deionized water was added. The mixture was heated to 200°C and held for 12 hours to obtain a preliminary compound. Then, under a nitrogen atmosphere, a reflux reaction was carried out and the mixture was held at 600°C for 6 hours to form a dense layered structure of Nb-TiO2. (3) Preparation of Fe2O3 nanoarray: A solution of 5 mol / L ferric nitrate and 0.71 mol / L isopropanol titanate in acidic isopropanol was coated on the Nb-TiO2 dense layer prepared in step (2), placed in a sealed hydrothermal reactor and deionized water was added. The mixture was heated to 120°C and kept for 4 hours. (4) Preparation of CH3NH3PbI3-xBrx thin film: A mixture of methyl iodide (CH3NH3I) and lead iodide (PbI2) was dissolved in a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to form a CH3NH3PbI3 perovskite precursor solution. This CH3NH3PbI3 perovskite precursor solution was then coated onto the Fe2O3 nanoarray prepared in step (3). The CH3NH3PbI3 perovskite thin film was then placed on a hot stage and sequentially heated in air. Annealing for 25 min, annealing for 3 min in a mixed hot steam containing air DMSO, HBr and H2O, annealing for 10 min in a mixed hot steam containing air CH3NH2 and H2O, with the hot stage temperature always maintained at 100℃, and a cleaning process combined with a multi-step atmosphere annealing process, to produce a CH3NH3PbI3-xBrx perovskite film with a molar ratio of CH3NH3I to CH3NH3Br of 85:15; (5) Preparation of hole transport layer: The spiro-OMeTAD solution is coated on the Nb-TiO2 dense layer and CH3NH3PbI3-xBrx thin film prepared in steps (1) to (4) and heat-treated to form a hole transport layer.

[0035] Example 3 A perovskite solar cell with Fe2O3 nanorod arrays, the preparation method includes the following steps: (1) Etching and cleaning of conductive substrate: The FTO conductive glass substrate was cut into a rectangle of 20mm×15mm, zinc powder was spread on it, and 6mol / L hydrochloric acid was added for etching. After 10 minutes, the hydrochloric acid was rinsed off with deionized water, and then ultrasonically cleaned and dried with nitrogen gas for later use. (2) Preparation of Nb-TiO2 dense layer: A solution of 7 mol / L niobium pentachloride and 1 mol / L isopropyl titanate in acidic isopropanol was coated on the conductive substrate prepared in step (1), placed in a closed hydrothermal reactor and deionized water was added. The mixture was heated to 160°C and held for 4 hours to obtain a preliminary compound. Then, under a nitrogen atmosphere, a reflux reaction was carried out and the mixture was held at 300°C for 2 hours to form a dense layered structure of Nb-TiO2. (3) Preparation of Fe2O3 nanoarray: A solution of 5 mol / L ferric nitrate and 1.67 mol / L isopropanol titanate in acidic isopropanol was coated on the Nb-TiO2 dense layer prepared in step (2), placed in a sealed hydrothermal reactor and deionized water was added. The mixture was heated to 200°C and kept for 4 hours. (4) Preparation of CH3NH3PbI3-xBrx thin film: A mixture of methyl iodide (CH3NH3I) and lead iodide (PbI2) was dissolved in a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to form a CH3NH3PbI3 perovskite precursor solution. This CH3NH3PbI3 perovskite precursor solution was then coated onto the Fe2O3 nanoarray prepared in step (3). The CH3NH3PbI3 perovskite thin film was then placed on a hot stage and sequentially heated in air. Annealing for 40 min, annealing for 8 min in a mixed hot steam containing air DMSO, HBr and H2O, annealing for 10 min in a mixed hot steam containing air CH3NH2 and H2O, with the hot stage temperature always maintained at 100℃, and a cleaning process combined with a multi-step atmosphere annealing process, to produce a CH3NH3PbI3-xBrx perovskite film with a molar ratio of CH3NH3I to CH3NH3Br of 85:15; (5) Preparation of hole transport layer: The spiro-OMeTAD solution is coated on the Nb-TiO2 dense layer and CH3NH3PbI3-xBrx thin film prepared in steps (1) to (4) and heat-treated to form a hole transport layer.

[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a Fe2O3 nanorod array perovskite solar cell, characterized in that, Includes the following steps: (1) Etching and cleaning of conductive substrate; (2) Preparation of Nb-TiO2 dense layer: A solution of niobium pentachloride and isopropyl titanate in acidic isopropanol was coated on the conductive substrate prepared in step (1), placed in a closed hydrothermal reactor and deionized water was added. The mixture was heated to 160-200℃ and held for 4-12 hours to obtain a preliminary compound. Then, under a nitrogen atmosphere, a reflux reaction was carried out and the mixture was held at 300-600℃ for 2-6 hours to form a dense layered structure of Nb-TiO2. (3) Preparation of Fe2O3 nanoarray: A solution of ferric nitrate and isopropyl titanate in acidic isopropanol was coated on the Nb-TiO2 dense layer prepared in step (2), placed in a sealed hydrothermal reactor and deionized water was added. The mixture was heated to 120-200℃ and kept for 4-12 hours. (4) Preparation of CH3NH3PbI3-xBrx thin film: CH3NH3PbI3-xBrx perovskite thin film with a molar ratio of CH3NH3I:CH3NH3Br=85:15 was prepared on Fe2O3 nanoarray by a two-step continuous deposition method; (5) Preparation of hole transport layer: A spiro-OMeTAD solution is coated on the Nb-TiO2 dense layer and CH3NH3PbI3-xBrx thin film prepared in steps (1) to (4) to form a hole transport layer.

2. The preparation method according to claim 1, characterized in that, Step (1) specifically includes: etching the conductive substrate according to the pattern required for the perovskite solar cell structure using zinc powder and 1-6 mol / L hydrochloric acid, followed by ultrasonic cleaning and nitrogen drying for later use.

3. The preparation method according to claim 1, characterized in that, In step (1), the conductive substrate is any one of ITO, FTO, and AZO.

4. The preparation method according to claim 3, characterized in that, In step (1), the conductive substrate is FTO.

5. The preparation method according to claim 1, characterized in that, In step (2), the molar ratio of niobium pentachloride and isopropyl titanate is (3-7):

1.

6. The preparation method according to claim 1, characterized in that, In step (3), the molar ratio of ferric nitrate to isopropyl titanate is (3-7):

1.

7. The preparation method according to claim 1, characterized in that, Step (4) specifically includes the following steps: methyl iodide (CH3NH3I) and lead iodide (PbI2) are mixed and dissolved in a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to form a CH3NH3PbI3 perovskite precursor solution. Then, the CH3NH3PbI3 perovskite precursor solution is coated onto the Fe2O3 nanoarray prepared in step (3). The CH3NH3PbI3 perovskite film is placed on a hot stage and annealed sequentially in an air atmosphere for 25-40 min, in a mixed hot steam containing air (DMSO, HBr, and H2O) for 3-8 min, in a hot steam containing air (DMSO) for 10 min, and in a mixed hot steam containing air (CH3NH2 and H2O) for 5-8 min. The hot stage temperature is always maintained at 100℃. The CH3NH3PbI3-xBrx film is prepared by cleaning and combining a multi-step atmosphere annealing process.

8. The preparation method according to claim 1, characterized in that, The CH3NH3PbI3-xBrx film was coated with spiro-OMeTAD solution and then subjected to heat treatment.

9. A perovskite solar cell with Fe2O3 nanorod arrays prepared by any one of the preparation methods according to claims 1 to 8.

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