Method for preparing perovskite thin film in perovskite solar cell and application thereof

Abstract

The application relates to a preparation method and application of a perovskite thin film in a perovskite solar cell. The perovskite solar cell is an n-i-p type perovskite solar cell; the perovskite thin film is prepared through a two-step spin coating method; a crystallization regulator is added in the second spin coating process; raw materials of the crystallization regulator include 1,4-butanediamine, 4-aminobenzoic acid and an anti-solvent. The technical problem to be solved is how to provide a perovskite thin film preparation method based on top-down crystallization, so that the prepared perovskite thin film has consistent grain orientation, low defect density and a smooth surface, and the photoelectric conversion efficiency of the perovskite battery can be improved.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, and in particular relates to a method for preparing perovskite thin films in perovskite solar cells and their applications. Background Technology

[0002] Perovskite solar cells, with their excellent photoelectric conversion efficiency, low-cost fabrication process, and tunable light absorption characteristics, have become a core research direction in next-generation photovoltaic technology. Among these factors, the crystallinity quality of the perovskite thin film directly determines the device's photoelectric performance, defect density, and long-term stability. Therefore, the thin film fabrication process and the control of crystallization behavior have become key technological bottlenecks for improving device performance.

[0003] Currently, traditional solution spin-coating is the mainstream method for preparing perovskite thin films, typically involving steps such as precursor solution spin-coating, solvent-resistant treatment, and thermal annealing. In this process, crystal growth usually follows a top-down pattern: crystal nuclei preferentially form at the conductive substrate interface and extend vertically towards the film surface. However, factors such as local roughness differences on the substrate surface, uneven surface energy distribution, and fluctuations in solvent evaporation rates often lead to insufficient density of the underlying crystals, small grain size, and random orientation. These structural defects not only significantly increase grain boundary density and bottom porosity but also increase the probability of nonradiative recombination of charge carriers, directly reducing photoelectric conversion efficiency. Summary of the Invention

[0004] The main objective of this invention is to provide a method for preparing perovskite thin films in perovskite solar cells. The technical problem to be solved is how to provide a method for preparing perovskite thin films based on top-down crystallization, which can make the prepared perovskite thin films have consistent grain orientation, low defect density and smooth surface, thereby improving the photoelectric conversion efficiency of perovskite solar cells.

[0005] The objective of this invention and the technical problem it solves are achieved by the following technical solution. According to this invention, a method for preparing a perovskite thin film in a perovskite solar cell is proposed. The perovskite solar cell is a nip-type perovskite solar cell. The perovskite thin film is prepared by a two-step spin-coating method. A crystallization regulator is added during the second spin-coating process. The raw materials of the crystallization regulator include 1,4-butanediamine, 4-aminobenzoic acid, and an antisolvent.

[0006] Preferably, in the aforementioned method for preparing perovskite thin films, the molar ratio of the 1,4-butanediamine to the 4-aminobenzoic acid and the antisolvent is 1:1:100.

[0007] Preferably, in the aforementioned method for preparing perovskite thin films, the antisolvent is selected from any one or more of toluene, ethyl acetate, chlorobenzene, and anisole.

[0008] Preferably, in the aforementioned method for preparing the perovskite thin film, the perovskite thin film is prepared using a two-step spin-coating method, the preparation method comprising:

[0009] S1. Prepare a perovskite precursor solution, and then drop-coat the perovskite precursor solution onto the surface of a conductive substrate;

[0010] S2. Prepare the crystallization regulator for later use;

[0011] S3. The conductive substrate coated with the perovskite precursor solution is rotated once at a speed of 900-1100 rpm for 8-12 s. After the rotation is completed, it is rotated a second time at a speed of 4500-5500 rpm for 8-10 s. Then the crystallization regulator is added and the rotation is continued for 10-12 s to obtain a wet film.

[0012] S4. The obtained wet film is immediately annealed to obtain the perovskite thin film.

[0013] Preferably, in the aforementioned method for preparing perovskite thin films, the method for preparing the crystallization regulator includes: adding 1,4-butanediamine and 4-aminobenzoic acid to an antisolvent, heating and continuously stirring until the solution is clear and transparent, so that the 1,4-butanediamine and 4-aminobenzoic acid are fully dissolved and uniformly dispersed to obtain the crystallization regulator.

[0014] Preferably, in the aforementioned method for preparing perovskite thin films, the molar ratio of 1,4-butanediamine to 4-aminobenzoic acid and the antisolvent is 1:1:100; the heating temperature is 40–60°C; and the stirring speed is 200–400 rpm.

[0015] Preferably, in the aforementioned method for preparing perovskite thin films, the annealing temperature is 100–150°C, and the annealing time is 20–30 min.

[0016] Preferably, in the aforementioned method for preparing perovskite thin films, the perovskite precursor solution comprises: formamidinium iodide, methylamine iodide, cesium iodide, lead iodide, N,N-dimethylformamide, and dimethyl sulfoxide.

[0017] Preferably, in the aforementioned method for preparing perovskite thin films, the conductive substrate needs to be pretreated. The pretreatment method includes: ultrasonically cleaning the conductive substrate sequentially in deionized water, anhydrous ethanol, and isopropanol solutions; after cleaning, drying it for later use.

[0018] The objectives of this invention and the solutions to its technical problems are also achieved by the following technical solutions. According to this invention, a perovskite solar cell is a nip-type perovskite solar cell; the perovskite solar cell includes a perovskite thin film; the perovskite thin film is prepared by the above-mentioned method for preparing perovskite thin films in perovskite solar cells.

[0019] By employing the above technical solution, the method for preparing perovskite thin films in perovskite solar cells proposed in this invention and its application have at least the following advantages:

[0020] This invention discloses a method for preparing perovskite thin films for perovskite solar cells. Unlike traditional top-down crystallization methods, this invention employs a top-down crystallization approach, specifically: a two-step spin-coating method is used to prepare the perovskite thin film. The key step is the addition of a crystallization regulator containing 1,4-butanediamine, 4-aminobenzoic acid, and an antisolvent during the second spin-coating process. By introducing a crystallization regulator containing amine groups onto the surface of the perovskite thin film layer, combined with antisolvent-induced and thermal annealing processes, an ordered top-down crystallization pattern of the perovskite thin film can be achieved. Furthermore, the crystallization regulator disclosed in this invention can perform the following functions:

[0021] 1. Ordered crystallization from top to bottom: Compared with the traditional top-down crystallization method, the addition of the crystallization regulator disclosed in this invention can achieve ordered crystallization from top to bottom. Through the amino groups contained in 1,4-butanediamine and 4-aminobenzoic acid, and in combination with the antisolvent, energy-dominant sites can be preferentially constructed on the surface of the film, and then the crystal nuclei are induced to grow downward from the surface and gradually extend to the substrate surface, forming a vertical gradient crystallization path of "upper layer crystal nuclei - middle layer grain extension - dense filling of the substrate".

[0022] 2. Grain morphology and orientation: The introduction of 1,4-butanediamine and 4-aminobenzoic acid can form energy-dominant sites on the film surface, inducing preferential crystal growth, thereby significantly increasing the grain size of the perovskite film, making the orientation highly consistent, and significantly reducing the number of grain boundaries, thus improving the carrier transport path and increasing the electron mobility.

[0023] 3. Deep passivation of interface defects: The top-down crystallization mode promotes the gradual filling of the crystal to the substrate surface. Combined with the interface passivation effect of the bisamine molecules, the bottom crystal becomes more compact, and the interface defect density is significantly reduced. This deep passivation effect effectively reduces the impact of carrier recombination and interface trapped states on device performance, thereby improving the carrier transport characteristics and overall optoelectronic performance of the device.

[0024] 4. Thin film uniformity: The uniform distribution of crystal nuclei and the vertical extension mechanism of "upper layer crystal nuclei - middle layer grain extension - dense substrate filling" ensure the uniformity of thin film thickness, improve the flatness of the thin film surface, and thus facilitate the interface contact of the subsequent hole / electron transport layer, thereby improving the overall performance of the device.

[0025] 5. Comprehensive Improvement in Device Performance: The perovskite thin film disclosed in this invention can be applied to nip-type perovskite solar cells, effectively improving the photoelectric conversion efficiency of perovskite solar cells. More importantly, through grain orientation optimization, defect density reduction, and film compaction enhancement, the long-term stability of the device is significantly improved, thereby promoting the widespread application of perovskite solar cells and laying a solid foundation for their industrial application.

[0026] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the 1,4-butanediamine structure of the present invention;

[0028] Figure 2 This is a schematic diagram of the 4-aminobenzoic acid structure of the present invention;

[0029] Figure 3 This is a schematic diagram illustrating the top-down control of perovskite crystallization according to the present invention;

[0030] Figure 4 These are scanning electron microscope (SEM) images of the perovskite thin film surfaces of Example 1 and Comparative Example 1 of the present invention.

[0031] Figure 5 The results of space charge confinement current tests on perovskite solar cells of Embodiment 1 and Comparative Example 1 of this invention are shown.

[0032] Figure 6 The JV curves are for the perovskite solar cells of Example 1 and Comparative Example 1 of this invention. Detailed Implementation

[0033] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the preparation method and application of a perovskite thin film in a perovskite solar cell according to the present invention, including its specific implementation, structure, features, and effects. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0034] This invention proposes a method for preparing a perovskite thin film in a perovskite solar cell, wherein the perovskite solar cell is a nip-type perovskite solar cell; the perovskite thin film is prepared by a two-step spin coating method; wherein a crystallization regulator is added during the second spin coating process; the raw materials of the crystallization regulator include: 1,4-butanediamine, 4-aminobenzoic acid and an antisolvent.

[0035] This invention discloses the addition of a crystallization regulator during the second spin coating process. The crystallization regulator, as a core raw material, comprises 1,4-butanediamine, 4-aminobenzoic acid, and an antisolvent. Specifically, the structural formula of 1,4-butanediamine (BDA) is shown below. Figure 1 As shown, the structural formula of 4-aminobenzoic acid (ABA) is as follows: Figure 2 As shown. Both compounds contain active amine groups in their molecular structures. Figure 3 As shown, these amino groups can form coordination interactions with Pb²⁺ ions in the perovskite precursor, simultaneously creating energy-dominant sites on the film surface, thereby inducing preferential crystal nucleation on the upper layer of the film. The crystallization method disclosed in this invention differs from the traditional top-down crystal growth model. The method employed in this invention can directly form initial crystal nuclei on the film surface, and with the rapid induction of crystal nucleation by the antisolvent, the crystal can gradually extend from top to bottom to the substrate interface.

[0036] Furthermore, the introduction of BDA and ABA significantly optimizes the solvent environment on the film surface, enhancing the interaction between the solvent and precursor molecules. This effectively slows down the excessively rapid growth rate of crystal nuclei, reduces the number of grain boundaries, and ultimately results in a more uniform and dense film structure. This method can also be combined with annealing processes. The modulating effects of BDA and ABA not only further improve the orientation consistency of the grains and the flatness of the film but also significantly reduce the defect density at the bottom interface. This series of improvements significantly optimizes carrier transport performance, thereby enhancing the photoelectric conversion efficiency and long-term operational stability of the device.

[0037] In summary, this invention achieves top-down ordered crystallization of perovskite thin films through the surface modulation effects of BDA and ABA, combined with antisolvent-induced technology and thermal annealing. This method provides a new technical approach for fabricating high-performance, high-stability perovskite solar cells and related optoelectronic devices.

[0038] Preferably, in the aforementioned method for preparing perovskite thin films, the molar ratio of the 1,4-butanediamine to the 4-aminobenzoic acid and the antisolvent is 1:1:100.

[0039] This invention discloses the composition of raw materials in a crystallization regulator. By controlling the molar ratio of the raw materials, it is possible to ensure that BDA and ABA form an ideal synergistic effect in the antisolvent. After the ratio is optimized, it can effectively suppress excessive crystallization or random nucleation, produce a uniform grain size distribution, reduce pinholes and defects, thereby improving the electronic properties of the thin film and thus improving the photoelectric conversion efficiency of perovskite solar cells.

[0040] It is worth noting that the amount of BDA and ABA added in this invention is kept as low as possible, so as to avoid damaging the perovskite lattice structure and maintain the photoelectric conversion efficiency of the perovskite solar cell; however, the amount added cannot be too low, otherwise the crystallization regulator will not be able to play its role.

[0041] Preferably, in the aforementioned method for preparing perovskite thin films, the antisolvent is selected from any one or more of toluene, ethyl acetate, chlorobenzene, and anisole.

[0042] This invention discloses the types of raw materials for the antisolvent, which can rapidly extract the solvent from the precursor solution, thereby enabling the perovskite film to crystallize quickly and uniformly. Furthermore, it is necessary to ensure the compatibility of the antisolvent with the perovskite precursor solution components to effectively avoid phase separation and side reactions, thus obtaining a high-quality perovskite film with a dense structure and smooth surface.

[0043] Preferably, in the aforementioned method for preparing the perovskite thin film, the perovskite thin film is prepared using a two-step spin-coating method, the preparation method comprising:

[0044] S1. Prepare a perovskite precursor solution, and then drop-coat the perovskite precursor solution onto the surface of a conductive substrate;

[0045] S2. Prepare the crystallization regulator for later use;

[0046] S3. The conductive substrate coated with the perovskite precursor solution is rotated once at a speed of 900-1100 rpm for 8-12 s. After the rotation is completed, it is rotated a second time at a speed of 4500-5500 rpm for 8-10 s. Then the crystallization regulator is added and the rotation is continued for 10-12 s to obtain a wet film.

[0047] S4. The obtained wet film is immediately annealed to obtain the perovskite thin film.

[0048] This invention discloses a specific method for top-down crystallization control of perovskite thin films. The specific operation involves: drop-coating a crystallization regulator onto the surface of a pretreated conductive substrate, followed by a two-step spin-coating process to form a perovskite thin film; the two-step spin-coating method consists of a first spin-coating (low-speed spin-coating) followed by a second spin-coating (high-speed spin-coating). The most crucial step in the two-step spin-coating process is adding the crystallization regulator during the second high-speed spin-coating, approximately 8-10 seconds into the process. This operation ensures the preferential distribution of diamine molecules on the film surface and works synergistically with the antisolvent to induce preferential growth of crystal nuclei on the upper layer of the film, thus achieving an orderly top-down crystallization process. The formed wet perovskite thin film is then rapidly transferred to a hot plate for annealing, promoting the steady extension of perovskite crystals from top to bottom until they completely cover the substrate interface. Through this series of crystallization control manipulations, the grain size of the prepared perovskite thin film can be significantly increased, the orientation is highly consistent, and the surface flatness is excellent. At the same time, the bottom defect density is also greatly reduced, thereby enabling the perovskite solar cell to have excellent photoelectric conversion efficiency.

[0049] It is worth noting that the crystallization regulator is added during high-speed rotation to ensure maximum regulation effect. The amount of crystallization regulator added is related to the size of the conductive substrate; generally, the area of ​​the conductive substrate is 1–2 cm². 2 Add 80–90 μL of crystallization regulator.

[0050] Preferably, in the aforementioned method for preparing perovskite thin films, the method for preparing the crystallization regulator includes: adding 1,4-butanediamine and 4-aminobenzoic acid to an antisolvent, heating and continuously stirring until the solution is clear and transparent, so that the 1,4-butanediamine and 4-aminobenzoic acid are fully dissolved and uniformly dispersed to obtain the crystallization regulator.

[0051] Preferably, in the aforementioned method for preparing perovskite thin films, the molar ratio of 1,4-butanediamine to 4-aminobenzoic acid and the antisolvent is 1:1:100; the heating temperature is 40–60°C; and the stirring speed is 200–400 rpm.

[0052] This invention discloses a method for preparing a crystallization regulator, which is a key step in this invention. Specifically, 1,4-Butanediamine (BDA) and 4-aminobenzoic acid (ABA) are first added to an antisolvent at a 1:1 molar ratio, and initial dissolution is achieved by magnetic stirring. Then, the remaining antisolvent is added to form a composite solution system with BDA:ABA:antisolvent = 1:1:100. This effectively avoids the precipitation of amine compounds or side reactions caused by excessively high local concentrations, ensuring solution homogeneity.

[0053] This invention discloses that the temperature is controlled at 40-60°C when preparing the crystallization regulator. Too high a temperature will cause oxidation of the amine compound or evaporation of the solvent, resulting in changes in composition. Too low a temperature will result in a slow dissolution rate and prolong the preparation time. Therefore, the optimal temperature is controlled at 40-60°C.

[0054] In the preparation process of the crystallization regulator of this invention, controlling the stirring speed to 200–400 rpm ensures that there is no solid residue or phase separation. This invention does not impose excessive restrictions on the stirring time; the stirring time is judged by the solution reaching a completely transparent state, which typically requires 30–45 minutes.

[0055] Preferably, the preparation method disclosed in this invention needs to be completed in a nitrogen glove box or a constant temperature and humidity desiccator to prevent the intrusion of water vapor and oxygen from causing amine group failure or changes in solvent properties.

[0056] Preferably, the present invention provides a criterion for determining the dissolution endpoint, specifically: the solution should be completely transparent and homogeneous, and the presence of undissolved microcrystals should be detected by visual observation and / or by using an ultraviolet lamp. If necessary, a 0.22μm PTFE filter head should be used for sterile filtration to remove trace amounts of insoluble matter.

[0057] It is worth noting that the prepared crystallization regulator should be sealed and stored away from light, and can be stored in an amber glass bottle. Furthermore, the prepared crystallization regulator should be used within 8 hours to avoid affecting the passivation effect due to decreased activity of the amine compounds or solvent evaporation.

[0058] Preferably, in the aforementioned method for preparing perovskite thin films, the annealing temperature is 100–150°C, and the annealing time is 20–30 min.

[0059] This invention optimizes the annealing process. The conductive substrate needs to be annealed immediately after two spin-coating processes. The transfer speed must be strictly controlled throughout the transfer process; preferably, it is 5–10 mm / s, to avoid solvent residue leading to uneven perovskite film. This invention discloses the annealing temperature and time. Setting the temperature to 100–150°C and the annealing time to 20–30 minutes ensures a uniform perovskite film. Excessive annealing time can lead to abnormal grain growth or passivation molecule failure; insufficient annealing time results in incomplete crystallization and passivation, thus reducing the photoelectric conversion efficiency of the perovskite solar cell. Preferably, the annealing operation disclosed in this invention should be performed in an inert atmosphere and / or a dry environment to avoid water and oxygen interference and material thermal decomposition, which could degrade the electrical properties of the perovskite film and consequently reduce the photoelectric conversion efficiency of the perovskite solar cell. After annealing, a programmed temperature-controlled cooling system is used to naturally cool the film to room temperature at a rate of 0.5–2 °C / min, avoiding thermal shock that could cause stress cracking or defects. Environmental cleanliness is continuously monitored during the cooling process to prevent film contamination or performance degradation.

[0060] Preferably, in the aforementioned method for preparing perovskite thin films, the perovskite precursor solution comprises: formamidinium iodide, methylamine iodide, cesium iodide, lead iodide, N,N-dimethylformamide, and dimethyl sulfoxide. The molar ratio of formamidinium iodide, methylamine iodide, cesium iodide, and lead iodide is 1:1:0.1:1.1.

[0061] The crystallization regulator disclosed in this invention is applicable to different perovskite components (such as pure FA system), various conductive substrates (FTO and ITO, etc.) and diverse device structures. It can maintain consistent performance in repeated preparation processes and has significant technical promotion value and industrial application prospects.

[0062] Preferably, in the aforementioned method for preparing perovskite thin films, the conductive substrate needs to be pretreated. The pretreatment method includes: ultrasonically cleaning the conductive substrate sequentially in deionized water, anhydrous ethanol, and isopropanol solutions; after cleaning, drying it for later use.

[0063] The conductive substrate disclosed in this invention is a conductive glass with high light transmittance and low surface roughness, preferably fluorine-doped tin oxide (FTO) or indium tin oxide (ITO) conductive glass. The thickness of the conductive substrate is 200–500 nm.

[0064] Furthermore, the method disclosed in this invention is simple in process and has good repeatability and reliability. It is not only suitable for the fine research needs of small-sized substrates (<1cm²) in the laboratory, but can also be extended to the continuous production line scenario of large-area substrates (≥1cm×1cm). The diamine regulator can be applied simultaneously with the antisolvent using large-scale processes such as slot coating, blade coating, or spraying. It precisely induces nucleation at the gas-liquid interface and forms energy-dominant sites. At the same time, it suppresses defect generation through a grain boundary selective passivation mechanism. This mode remains highly efficient in large-area preparation, ensuring good uniformity of film grains. Meanwhile, this method has relaxed requirements for annealing conditions, with a wide temperature window of 100-180℃ (the specific value is optimized according to the production line equipment parameters). It allows process fluctuations of ±10℃ while maintaining device performance stability, greatly reducing the difficulty of process control in large-scale production and demonstrating strong adaptability.

[0065] The present invention also proposes a perovskite thin film, which is prepared by the above-described preparation method.

[0066] The present invention also proposes a perovskite solar cell, wherein the perovskite solar cell is a nip-type perovskite solar cell; the perovskite solar cell includes a perovskite thin film; the perovskite thin film is prepared by the above-mentioned method for preparing perovskite thin films in perovskite solar cells.

[0067] The perovskite thin film disclosed in this invention can be applied in perovskite solar cells. Its preparation method is as follows: the perovskite thin film obtained after annealing is placed in a vapor deposition glove box, and C is deposited sequentially. 60 The device was fabricated by constructing a hole transport layer (20–25 nm thick, velocity 0.1–0.3 Å / s), a BCP electron blocking layer (5–7 nm thick, velocity 0.05–0.15 Å / s), and an Ag metal electrode (90 nm thick, velocity 1–2 Å / s).

[0068] The present invention will be further described below with reference to specific embodiments, but this should not be construed as a limitation on the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention still fall within the scope of protection of the present invention.

[0069] Unless otherwise specified, all materials and reagents mentioned below are commercially available products well known to those skilled in the art; unless otherwise specified, all methods described are methods known in the art. Unless otherwise defined, the technical or scientific terms used should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0070] Example 1

[0071] A perovskite solar cell, the preparation method of which includes:

[0072] 1) Preparation of perovskite thin films:

[0073] 1.1) Preprocessing:

[0074] The FTO conductive substrate was ultrasonicated with deionized water, ethanol and isopropanol for 15 minutes in sequence, and then dried with dry air for later use.

[0075] 1.2) Preparation of perovskite precursor solution:

[0076] 219.3 mg formamidinium iodide (FAI), 23.8 mg methylamine iodide (MAI), 19.3 mg cesium iodide (CsI), and 691.6 mg lead iodide (PbI2) were dissolved in 1 mL of a mixed solvent (composed of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of 4:1), and then stirred continuously at 25℃±5℃ for more than 12 h (overnight) to obtain a clear and homogeneous perovskite precursor solution with a concentration of 1.5 M.

[0077] 1.3) Prepare 20 mL of a crystallization regulator consisting of BDA:ABA:ethyl acetate (molar ratio 1:1:100):

[0078] 172.0 mg BDA and 26.9 mg ABA were mixed. After ABA was pre-dissolved in a small amount of ethyl acetate, it was mixed with BDA and the remaining solvent and the volume was adjusted to 20 mL. The mixture was heated at 40 °C and stirred at 200 rpm until the solution was clear and transparent to obtain the crystallization regulator.

[0079] 1.4) Preparation of perovskite thin films:

[0080] The prepared perovskite precursor solution was drop-coated onto the surface of a pretreated conductive substrate, and then rotated once at a speed of 900 rpm for 8 s. After the rotation, it was rotated a second time at a speed of 4500 rpm for 8 s. Then, a crystallization regulator was added, and the rotation was continued for 10 s to obtain a wet film. The wet film was then immediately placed on a hot plate for annealing at a temperature of 100℃ for 20 min to obtain a perovskite thin film.

[0081] 2) Fabrication of perovskite solar cells:

[0082] The perovskite film obtained after annealing was placed in a vapor deposition glove box, and C was deposited sequentially. 60 A perovskite solar cell was obtained by constructing a hole transport layer (20 nm thick, 0.1 Å / s), a BCP electron blocking layer (5 nm thick, 0.05 Å / s), and an Ag metal electrode (90 nm thick, 1 Å / s).

[0083] Example 2

[0084] A perovskite solar cell, the preparation method of which includes:

[0085] 1) Preparation of perovskite thin films:

[0086] 1.1) Preprocessing:

[0087] The FTO conductive substrate was ultrasonicated with deionized water, ethanol and isopropanol for 15 minutes in sequence, and then dried with dry air for later use.

[0088] 1.2) Preparation of perovskite precursor solution:

[0089] 219.3 mg formamidinium iodide (FAI), 23.8 mg methylamine iodide (MAI), 19.3 mg cesium iodide (CsI), and 691.6 mg lead iodide (PbI2) were dissolved in 1 mL of a mixed solvent (composed of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of 4:1), and then stirred continuously at 25℃±5℃ for more than 12 h (overnight) to obtain a clear and homogeneous perovskite precursor solution with a concentration of 1.5 M.

[0090] 1.3) Prepare 20 mL of a crystallization regulator consisting of BDA:ABA:ethyl acetate (molar ratio 1:1:100):

[0091] 172.0 mg BDA and 26.9 mg ABA were mixed. After the ABA was pre-dissolved in a small amount of ethyl acetate, the mixture was combined with BDA and the remaining solvent and brought to a final volume of 20 mL. The mixture was heated at 40–60 °C and stirred at 200–400 rpm until the solution became clear and transparent, thus obtaining the crystallization regulator.

[0092] 1.4) Preparation of perovskite thin films:

[0093] The prepared perovskite precursor solution was drop-coated onto the surface of a pretreated conductive substrate, and then rotated once at a speed of 950 rpm for 10 s. After the rotation, a second rotation was performed at a speed of 5000 rpm for 9 s. Then, a crystallization regulator was added, and the rotation was continued for 10-12 s to obtain a wet film. The wet film was then immediately placed on a hot plate for annealing at a temperature of 120℃ for 25 min to obtain a perovskite thin film.

[0094] 2) Fabrication of perovskite solar cells:

[0095] The perovskite film obtained after annealing was placed in a vapor deposition glove box, and C was deposited sequentially. 60A perovskite solar cell was obtained by constructing a hole transport layer (22 nm thick, 0.2 Å / s), a BCP electron blocking layer (6 nm thick, 0.1 Å / s), and an Ag metal electrode (90 nm thick, 1.5 Å / s).

[0096] Example 3

[0097] A perovskite solar cell, the preparation method of which includes:

[0098] 1) Preparation of perovskite thin films:

[0099] 1.1) Preprocessing:

[0100] The FTO conductive substrate was ultrasonicated with deionized water, ethanol and isopropanol for 15 minutes in sequence, and then dried with dry air for later use.

[0101] 1.2) Preparation of perovskite precursor solution:

[0102] 219.3 mg formamidinium iodide (FAI), 23.8 mg methylamine iodide (MAI), 19.3 mg cesium iodide (CsI), and 691.6 mg lead iodide (PbI2) were dissolved in 1 mL of a mixed solvent (composed of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of 4:1), and then stirred continuously at 25℃±5℃ for more than 12 h (overnight) to obtain a clear and homogeneous perovskite precursor solution with a concentration of 1.5 M.

[0103] 1.3) Prepare 20 mL of a crystallization regulator consisting of BDA:ABA:ethyl acetate (molar ratio 1:1:100):

[0104] 172.0 mg BDA and 26.9 mg ABA were mixed. After the ABA was pre-dissolved in a small amount of ethyl acetate, it was mixed with BDA and the remaining solvent and the volume was adjusted to 20 mL. The mixture was heated at 60 °C and stirred at 400 rpm until the solution was clear and transparent to obtain the crystallization regulator.

[0105] 1.4) Preparation of perovskite thin films:

[0106] The prepared perovskite precursor solution was drop-coated onto the surface of a pretreated conductive substrate, and then rotated once at a speed of 1100 rpm for 12 s. After the rotation, a second rotation was performed at a speed of 5500 rpm for 10 s. Then, a crystallization regulator was added, and the rotation was continued for 12 s to obtain a wet film. The wet film was then immediately placed on a hot plate for annealing at a temperature of 150 °C for 30 min to obtain a perovskite thin film.

[0107] 2) Fabrication of perovskite solar cells:

[0108] The perovskite film obtained after annealing was placed in a vapor deposition glove box, and C was deposited sequentially. 60 A perovskite solar cell was obtained by constructing a hole transport layer (25 nm thick, 0.3 Å / s), a BCP electron blocking layer (7 nm thick, 0.15 Å / s), and an Ag metal electrode (90 nm thick, 2 Å / s).

[0109] Example 4

[0110] Compared to Example 1, the molar ratio of BDA, ABA and ethyl acetate in the crystallization regulator of Example 4 is 1:1:50.

[0111] Example 5

[0112] Compared to Example 1, the antisolvent in the crystallization regulator of Example 5 is chlorobenzene.

[0113] Comparative Example 1

[0114] Compared with Example 1, Comparative Example 1 did not include a crystallization regulator.

[0115] The morphology of the perovskite films of Example 1 (using BDA and ABA diamine molecules synergistically controlled with antisolvent) and Comparative Example 1 (conventional process) was characterized by scanning electron microscopy (SEM), and the results are as follows: Figure 4 As shown in the figure. Comparative analysis shows that the surface morphology of the perovskite film in Example 1 under the combined regulation of BDA, ABA, and antisolvent undergoes significant changes—the content of unreacted lead iodide (PbI2) phase is significantly reduced compared to Comparative Example 1, indicating a more complete crystallization process; simultaneously, the perovskite grain size is significantly increased, the number of grain boundaries is reduced, and passivation material is selectively distributed in the grain boundary regions, forming an effective passivation layer structure. This morphological characteristic demonstrates the synergistic effect mechanism of diamine molecules (BDA and ABA) in regulating crystallization kinetics (promoting preferential nucleation on the surface and inhibiting defect generation) and passivating grain boundary defects, thereby improving the photoelectric conversion efficiency and long-term operational stability of perovskite optoelectronic devices.

[0116] The perovskite solar cells prepared in Example 1 and Comparative Example 1 were subjected to space charge confinement current (SCLC) testing (their structure was: FTO / PEDOT:PSS / perovskite / Spiro-OMeTAD / Au). The results are as follows: Figure 5 As shown. (Through) Figure 5 It can be seen that the defect density of the perovskite solar cell in Example 1 is reduced from 1.26 × 10⁻⁶ in Comparative Example 1. 15 cm -3 Reduced to 7.38×10 14 cm -3The reduction was by an order of magnitude. This result directly demonstrates the efficient synergistic effect of the diamine molecules (BDA and ABA) in the passivation of grain boundaries and bulk defects. By binding with uncoordinated Pb²⁺ and filling halogen vacancies, they significantly suppress the generation of charge trap states, thereby improving the carrier transport characteristics and overall optoelectronic performance of the device.

[0117] The efficiency of the perovskite solar cells prepared in Example 1 and Comparative Example 1 was tested, and the results are as follows: Figure 6 As shown in Table 1.

[0118] Table 1: Efficiency of perovskite solar cells in Example 1 and Comparative Example 1

[0119]

[0120] pass Figure 6 As shown in Table 1, the perovskite solar cell prepared in Example 1 through the synergistic regulation of diamine molecules (BDA and ABA) and antisolvent exhibits a significantly improved photoelectric conversion efficiency. Compared to Comparative Example 1, the perovskite solar cell of Example 1 shows a significantly improved open-circuit voltage (V0). OC ), short-circuit current density (J SC Significant improvements were achieved in both the conversion efficiency and fill factor (FF), ultimately resulting in higher conversion efficiency. These results demonstrate the synergistic passivation and crystallization regulation effects of the diamine molecule in optimizing film quality, reducing non-radiative recombination loss, and promoting charge extraction.

[0121] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0122] 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 perovskite thin film in a perovskite solar cell, characterized in that, The perovskite solar cell is a nip-type perovskite solar cell; the perovskite thin film is prepared by a two-step spin coating method; wherein, a crystallization regulator is added during the second spin coating process; the raw materials of the crystallization regulator include: 1,4-butanediamine, 4-aminobenzoic acid and antisolvent; The molar ratio of the 1,4-butanediamine to the 4-aminobenzoic acid and the antisolvent is 1:1:100; The antisolvent is selected from any one or more of toluene, ethyl acetate, chlorobenzene, and anisole; The perovskite thin film is prepared by a two-step spin-coating method, the preparation method of which includes: S1. Prepare a perovskite precursor solution, and then drop-coat the perovskite precursor solution onto the surface of a conductive substrate; S2. Prepare the crystallization regulator for later use; S3. The conductive substrate coated with the perovskite precursor solution is rotated once at a speed of 900-1100 rpm for 8-12 s. After the rotation is completed, it is rotated a second time at a speed of 4500-5500 rpm for 8-10 s. Then the crystallization regulator is added and the rotation is continued for 10-12 s to obtain a wet film. S4. The obtained wet film is immediately annealed to obtain the perovskite thin film.

2. The method for preparing perovskite thin films according to claim 1, characterized in that, The preparation method of the crystallization regulator includes: adding 1,4-butanediamine and 4-aminobenzoic acid to an antisolvent, heating and continuously stirring until the solution is clear and transparent, so that the 1,4-butanediamine and 4-aminobenzoic acid are fully dissolved and uniformly dispersed to obtain the crystallization regulator.

3. The method for preparing perovskite thin films according to claim 2, characterized in that, The heating temperature is 40–60°C; the stirring speed is 200–400 rpm.

4. The method for preparing perovskite thin films according to claim 2, characterized in that, The annealing temperature is 100–150°C; the annealing time is 20–30 min.

5. The method for preparing perovskite thin films according to claim 1, characterized in that, The perovskite precursor solution comprises: formamidinium iodide, methylamine iodide, cesium iodide, lead iodide, N,N-dimethylformamide, and dimethyl sulfoxide.

6. The method for preparing a perovskite thin film according to any one of claims 1 to 5, characterized in that, The conductive substrate needs to be pretreated. The pretreatment method includes: ultrasonically cleaning the conductive substrate in deionized water, anhydrous ethanol and isopropanol solutions in sequence; after cleaning, drying it and setting it aside for later use.

7. A perovskite solar cell, characterized in that, The perovskite solar cell is a nip-type perovskite solar cell; the perovskite solar cell includes a perovskite thin film; the perovskite thin film is prepared by the method for preparing the perovskite thin film in the perovskite solar cell according to any one of claims 1 to 6.

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