A method for preparing a perovskite thin film with reduced residual stress of low-dimensional fatty amine halide perovskite

Abstract

This invention discloses a method for preparing perovskite thin films to reduce residual stress in low-dimensional halide perovskites. This method involves introducing an aromatic amine molecule, F-PEA, into the low-dimensional aliphatic amine halide perovskite, which significantly reduces the residual stress during the crystallization process of the perovskite, effectively improving the mechanical stability of the film. When the perovskite thin film prepared by this method is used as the active layer in solar cells, the performance and stability of the resulting solar cell devices are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of perovskite material technology, and more specifically to a method for preparing perovskite thin films that reduces residual stress in low-dimensional fatty amine halide perovskites. Background Technology

[0002] With ongoing research, perovskite, a special material, has gradually gained attention in fields such as optoelectronics, especially in solar cells using perovskite as the active layer, where it has seen rapid development in recent years. However, current applications of perovskite in various fields are limited by issues such as air, heat, and light stability. In recent years, the proposal of a quasi-two-dimensional perovskite has largely solved the air stability problem of perovskite. However, the two-dimensional quantum well structure formed by the introduction of some organic amine molecules hinders the transport of charge carriers within the perovskite, resulting in a decrease in photoelectric conversion efficiency. Therefore, we need to further optimize the phase composition, phase arrangement, and growth orientation of the perovskite to improve the charge carrier transport efficiency within the perovskite.

[0003] On the other hand, stress release during the perovskite crystallization process is a crucial factor in preparing perovskite films with higher mechanical stability. Residual stress has been reported to occur during the perovskite annealing process, primarily due to the mismatch in thermal expansion coefficients between the perovskite and the underlying substrate. Drastic temperature changes cause bottom-up lattice distortion in the perovskite, leading to decreased structural stability and impacting the lifespan of related devices. Therefore, methods are needed to regulate residual stress in the films to further improve the performance and stability of perovskite films and related devices. Summary of the Invention

[0004] The objective of this invention is to prepare a perovskite film in an air environment (>40% RH) by incorporating a small amount of aromatic amine F-PEA into a low-dimensional aliphatic amine halide perovskite. This preparation method reduces the residual stress caused by the difference in thermal expansion coefficients between the perovskite and the substrate during the crystallization process, further improving the stability of the perovskite. This optimized perovskite film can achieve higher device performance and stability in solar cell devices.

[0005] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0006] A method for preparing perovskite thin films to reduce residual stress in low-dimensional aliphatic amine halide perovskites includes the following steps:

[0007] (1) Preparation of precursor fluid

[0008] PbI2, MAI and fatty amine hydroiodide were weighed and dissolved in a mixed solvent of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), and heated and stirred overnight with a magnetic stirrer.

[0009] (2) Substrate pretreatment

[0010] The ITO conductive glass was ultrasonically treated in deionized water, ethanol, acetone and ethanol in sequence, then dried with a nitrogen gas gun, and finally treated with ultraviolet-ozone.

[0011] (3) Preparation of perovskite layer

[0012] Spin-coat the perovskite precursor liquid in (1) onto the pretreated substrate in (2), and then anneal for 5 min.

[0013] As an optional technical solution, the fatty amine hydroiodide in step (1) can be one of propylamine hydroiodide (PAI), isobutylamine hydroiodide (iso-BAI), or butylamine hydroiodide (BAI).

[0014] As an optional technical solution, the molar ratio of PbI2, MAI, F-PEAI and a fatty amine hydroiodide in step (1) is 4:3:0.2:1.8.

[0015] As an optional technical solution, the solvent volume ratio of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in step (1) is 9:1.

[0016] As an optional technical solution, the cleaning solvent in step (2) is deionized water, ethanol, acetone and ethanol in sequence, and the ultraviolet ozone treatment time in step (2) is 20-30 min.

[0017] As an optional technical solution, in step (3), the substrate needs to be preheated on an 80°C hot stage for 1-2 minutes before spin coating the perovskite.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. In this invention, a small amount of aromatic amine F-PEA is introduced into the low-dimensional aliphatic amine halide perovskite to further improve the structural stability of the perovskite and to enable the perovskite to be prepared in an air environment.

[0020] 2. In this invention, the introduction of a small amount of aromatic amine F-PEA into low-dimensional aliphatic amine halide perovskite enables directional vertical growth of perovskite and improves carrier transport efficiency.

[0021] 3. In this invention, a small amount of aromatic amine F-PEA is introduced into low-dimensional aliphatic amine halide perovskite and used in inverted solar cell devices, thereby achieving high photoelectric conversion efficiency and device stability. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the amine molecule structure involved in the patent;

[0023] Figure 2 GIXRD test results for different perovskite materials;

[0024] Figure 3 The graph shows the results of fitting the GIXRD test points using the Williamson-Hall formula.

[0025] Figure 4 This is a schematic diagram of a solar cell device structure;

[0026] Figure 5 This serves as a stability comparison for solar cell devices. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0029] The materials described below are as follows:

[0030] PbI2: Lead iodide;

[0031] MAI: Methylammonium iodide;

[0032] F-PEAI: 2-(4-fluorophenyl)ethylamine hydroiodate;

[0033] iso-BAI: Isobutylamine hydroiodide;

[0034] BAI: Butamine hydroiodide;

[0035] PAI: Propylamine hydroiodate;

[0036] DMF: Dimethylformamide;

[0037] DMSO: Dimethyl sulfoxide;

[0038] IPA: Isopropanol;

[0039] ITO: Indium Tin Oxide;

[0040] PTAA: Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine];

[0041] PC61BM: Fullerene derivative;

[0042] PEI: Polyetherimide.

[0043] Example 1

[0044] This embodiment provides a method for preparing perovskite thin films to reduce residual stress in low-dimensional aliphatic amine halide perovskites, comprising the following steps:

[0045] (1) Preparation of precursor solution

[0046] PbI2, MAI, F-PEAI, and iso-BAI were weighed and mixed in a molar ratio of 4:3:0.2:1.8. The solutes were then dissolved in a mixed solvent of DMF and DMSO in a volume ratio of 9:1. The solution was then placed on a hot plate at 60°C and stirred overnight.

[0047] (2) Substrate pretreatment

[0048] The ITO conductive glass substrate was ultrasonically treated in deionized water, ethanol, acetone and ethanol for 15 minutes each, then dried with a nitrogen gun and then subjected to ultraviolet-ozone treatment.

[0049] (3) Preparation of perovskite thin films

[0050] The pretreated substrate in (2) was preheated on a hot plate at 80°C for 1 min, and then the precursor liquid obtained in (1) was spin-coated onto the substrate at a spin speed of 5000 rpm and a spin time of 60 s. After spin coating, the substrate was placed on a hot plate at 100°C for annealing for 5 min.

[0051] Example 2

[0052] This embodiment provides a method for preparing perovskite thin films to reduce residual stress in low-dimensional aliphatic amine halide perovskites, comprising the following steps:

[0053] (1) Preparation of precursor solution

[0054] PbI2, MAI, F-PEAI, and BAI were weighed and mixed in a molar ratio of 4:3:0.2:1.8. The solutes were then dissolved in a mixed solvent of DMF and DMSO in a volume ratio of 9:1. The solution was then placed on a hot plate at 60°C and stirred overnight.

[0055] (2) Substrate pretreatment

[0056] The ITO conductive glass substrate was ultrasonically treated in deionized water, ethanol, acetone and ethanol for 15 minutes each, then dried with a nitrogen gun and then subjected to ultraviolet-ozone treatment.

[0057] (3) Preparation of perovskite thin films

[0058] The pretreated substrate in (2) was preheated on a hot plate at 80°C for 1 min, and then the precursor liquid obtained in (1) was spin-coated onto the substrate at a spin speed of 5000 rpm and a spin time of 60 s. After spin coating, the substrate was placed on a hot plate at 100°C for annealing for 5 min.

[0059] Example 3

[0060] This embodiment provides a method for preparing perovskite thin films to reduce residual stress in low-dimensional aliphatic amine halide perovskites, comprising the following steps:

[0061] (1) Preparation of precursor solution

[0062] PbI2, MAI, F-PEAI, and PAI were weighed and mixed according to a molar ratio of 4:3:0.2:1.8. The solute was then dissolved in a mixed solvent of DMF and DMSO in a volume ratio of 9:1. The solution was then placed on a hot plate at 60°C and stirred overnight.

[0063] (2) Substrate pretreatment

[0064] The ITO conductive glass substrate was ultrasonically treated in deionized water, ethanol, acetone and ethanol for 15 minutes each, then dried with a nitrogen gun and then subjected to ultraviolet-ozone treatment.

[0065] (3) Preparation of perovskite thin films

[0066] The pretreated substrate in (2) was preheated on a hot plate at 80°C for 1 min, and then the precursor liquid obtained in (1) was spin-coated onto the substrate at a spin speed of 5000 rpm and a spin time of 60 s. After spin coating, the substrate was placed on a hot plate at 100°C for annealing for 5 min.

[0067] Comparative Example 1

[0068] This comparative example provides a method for preparing low-dimensional fatty amine halide perovskite thin films, which differs from Example 1 in that:

[0069] (1) Preparation of precursor solution

[0070] PbI2, MAI and BAI were weighed and mixed in a molar ratio of 4:3:2. The solute was then dissolved in a mixed solvent of DMF and DMSO in a volume ratio of 9:1. The solution was then placed on a hot plate at 60°C and stirred overnight.

[0071] The remaining steps are the same as in Example 1.

[0072] Comparative Example 2

[0073] This comparative example provides a method for preparing low-dimensional fatty amine halide perovskite thin films, which differs from Example 1 in that:

[0074] (1) Preparation of precursor solution

[0075] PbI2, MAI, and iso-BAI were weighed and mixed in a molar ratio of 4:3:2. The solute was then dissolved in a mixed solvent of DMF and DMSO in a volume ratio of 9:1. The solution was then placed on a hot plate at 60°C and stirred overnight.

[0076] The remaining steps are the same as in Example 1.

[0077] Comparative Example 3

[0078] This comparative example provides a method for preparing a low-dimensional fatty amine halide perovskite thin film, which differs from Example 1 in that:

[0079] (1) Preparation of precursor solution

[0080] PbI2, MAI, and PAI were weighed and mixed in a molar ratio of 4:3:2. The solute was then dissolved in a mixed solvent of DMF and DMSO in a volume ratio of 9:1. The solution was then placed on a hot plate at 60°C and stirred overnight.

[0081] The remaining steps are the same as in Example 1.

[0082] The GIXRD patterns of the perovskite films prepared in Example 1 and Comparative Example 1 are shown below. Figure 3As shown. GIXRD (grazing incidence X-ray diffraction) was used to analyze the variation of interplanar spacing at different positions in the vertical direction of different perovskite films. We found that the shift of the diffraction peaks in Example 1 was significantly reduced as the grazing incidence angle changed compared to Comparative Example 1. Furthermore, the stress was fitted using the Williamson-Hall formula. The slope obtained from the fitting in the figure represents the magnitude of the film stress. It can be seen that the slope of the fitted line in Example 1 is significantly reduced compared to Comparative Example 1. This indicates that introducing a small amount of F-PEA into the low-dimensional isobutylamine halide perovskite can effectively reduce the residual stress in the film.

[0083] (Williamson-Hall formula: , where E is the perovskite modulus (10 GPa). v This is the Poisson's ratio of perovskite. It is the diffraction angle 2 corresponding to a given diffraction peak in stress-free perovskite. Half of (This represents residual stress.)

[0084] The thin films prepared in Examples 1-3 and Comparative Examples 1-3 were used as active layers to fabricate solar cells and their performance was tested. Specific device structures are shown in [reference needed]. Figure 4 As shown in Table 1, the device performance test results are shown in Table 1.

[0085] Table 1 Performance parameters of quasi-two-dimensional perovskite solar cells

[0086]

[0087] As shown in Table 1, compared with Comparative Examples 1-3, the photoelectric conversion efficiency of the solar cell devices prepared in Examples 1-3 is better than that of the initial perovskite solar cell devices. This indicates that the introduction of aromatic amine F-PEA into low-dimensional aliphatic amine halide perovskite can effectively improve the photoelectric conversion efficiency of the device.

[0088] The thin films prepared in Examples 1-3 and Comparative Examples 1-3 were used as active layers to fabricate solar cells, and the air stability of the devices was tested. The results are as follows: Figure 4 As shown.

[0089] pass Figure 4 It can be seen that, compared with Comparative Examples 1-3, the solar cell devices prepared in Examples 1-3 are all more stable in air than the initial perovskite solar cell devices. This indicates that the introduction of aromatic amine F-PEA into low-dimensional aliphatic amine halide perovskite can effectively improve the air stability of the device.

[0090] In summary, by introducing an aromatic amine F-PEA into low-dimensional aliphatic amine halide perovskites, we can effectively reduce the residual stress of the thin film during the preparation process. By using the improved perovskite thin film to prepare solar cell devices, we can further improve the photoelectric conversion efficiency of the devices and greatly enhance the stability of perovskite solar cell devices.

[0091] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing perovskite thin films to reduce residual stress in low-dimensional fatty amine halide perovskites, characterized in that, Includes the following steps: (1) Preparation of precursor fluid; Lead iodide (PbI2), methyl ammonium iodide (MAI), fatty amine hydroiodide and 2-(4-fluorophenyl)ethylamine hydroiodide (F-PEAI) were weighed and dissolved in a mixed solvent of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). The mixture was heated and stirred overnight with a magnetic stirrer. The molar ratio of lead iodide (PbI2), methyl ammonium iodide (MAI), 2-(4-fluorophenyl)ethylamine hydroiodate (F-PEAI), and aliphatic amine hydroiodate is 4:3:0.2:1.8; the volume ratio of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) is 9:

1. (2) Substrate pretreatment; The indium tin oxide (ITO) conductive glass was ultrasonically treated in deionized water, ethanol, acetone and ethanol in sequence, then dried with a nitrogen gas gun, and finally subjected to ultraviolet-ozone treatment. (3) Preparation of perovskite layer; The perovskite precursor liquid in (1) was spin-coated onto the pretreated substrate in (2), and then annealed for 5 min.

2. The method for preparing perovskite to reduce residual stress in low-dimensional fatty amine halide perovskite as described in claim 1, characterized in that, The fatty amine hydroiodide in step (1) is propylamine hydroiodide PAI, isobutylamine hydroiodide iso-BAI, or butylamine hydroiodide BAI.

3. A method for preparing perovskite to reduce residual stress in low-dimensional fatty amine halide perovskites as described in claim 1, characterized in that, Before spin-coating the perovskite in step (3), the substrate needs to be preheated on an 80°C hot plate for 1-2 minutes.

Images