Preparation method of low-dimensional perovskite thin film and solar cell thereof

Abstract

This invention relates to the field of perovskite solar cell technology, and discloses a method for preparing a low-dimensional perovskite thin film and its solar cell. The method for preparing the low-dimensional perovskite thin film is as follows: Step 1, weighing p-fluorophenylethylamine iodine, methyl iodide, lead iodide, formamidine iodide, methyl ammonium chloride, and lead chloride, and dispersing them in a mixed solution composed of dimethylformamide and dimethyl sulfoxide to obtain a low-dimensional perovskite precursor solution; Step 2, dropping the low-dimensional perovskite precursor solution onto a substrate, rapidly spin-coating for 10-20 seconds, and then subjecting it to reverse-order cooling annealing to obtain a low-dimensional perovskite thin film. This invention rapidly forms a low-dimensional perovskite wet film through high-speed spin-coating, followed by reverse-order cooling annealing, which not only enables the preparation of low-dimensional perovskite thin films with vertically grown multiphase structures, but also has good repeatability and reduces the manufacturing cost of battery devices. The reverse-order cooling annealing process described in this invention is simple and suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, and particularly to a method for preparing a low-dimensional perovskite thin film and its solar cell. Background Technology

[0002] Organic-inorganic hybrid perovskite materials have played a crucial role in the development of solar cells due to their advantages such as high light absorption, low binding energy, high defect tolerance, high carrier mobility, and long carrier diffusion length. Currently, three-dimensional perovskite solar cells have achieved a certified photoelectric conversion efficiency of 25.7%, but their low stability requires further optimization and improvement. Therefore, the stability of three-dimensional solar devices hinders their commercialization. Interestingly, low-dimensional perovskite solar cells exhibit excellent stability due to the hydrophobicity of their organic spacer cations, thus showing promising commercial application prospects.

[0003] Low-dimensional perovskite thin films, due to their multiphase structure, are semiconductor materials with multiple quantum well structures. Because of the quantum confinement effect of these structures, low-dimensional perovskite materials suffer from drawbacks such as low absorption coefficients, low carrier mobility, and high exciton binding energies, resulting in poor photovoltaic performance in low-dimensional perovskite solar cells. Research shows that controlling the multiphase structure in low-dimensional perovskite thin films is a simple and effective method to improve the photovoltaic performance of solar cell devices. When the multiphase structure in the low-dimensional perovskite thin film grows perpendicular to the substrate, it facilitates carrier separation, transport, and extraction, effectively improving the photovoltaic performance of the solar cell device. Common strategies for controlling the growth mode of the multiphase structure include additive engineering, solvent engineering, and thermal engineering. Thermal engineering strategies typically include continuous annealing, sequential heating annealing, and hot spin coating. Continuous annealing is a commonly used annealing process, resulting in a disordered arrangement of the multiphase structure in the low-dimensional perovskite thin film, primarily reducing the short-circuit current density in the solar cell device. While sequential temperature-increasing annealing can promote grain growth in low-dimensional perovskites, it cannot promote the vertical growth of multiphase structures within them. Verification has shown that thermal spin coating can effectively control the vertical growth of multiphase structures in low-dimensional perovskites, which is beneficial for improving the short-circuit current density of battery devices. However, thermal spin coating suffers from difficulties in controlling repeatability.

[0004] Chinese invention patent CN 108183166 B discloses a fluctuating annealing process and a perovskite solar cell fabricated using this process. The fluctuating thermal annealing process induces a rapid-slow-rapid-slow growth cycle in the perovskite grains, allowing the perovskite active layer grains to grow. During the slow growth phase, self-assembly occurs between the perovskite grains, resulting in denser and more uniform contact between the grains. However, while this fluctuating thermal annealing process is effective for three-dimensional perovskite films, it is not suitable for low-dimensional perovskite films. In the formation of low-dimensional perovskite films, multiphase structures with different n values ​​easily and quickly form. Prolonged high-temperature exposure can severely damage the low-dimensional perovskite film. Therefore, finding an efficient and effective method for the growth of low-dimensional perovskite films is our research topic. Summary of the Invention

[0005] Objective of the Invention: Addressing the problems existing in the prior art, this invention provides a method for preparing low-dimensional perovskite thin films and their solar cells. The method involves rapidly forming a low-dimensional perovskite wet film through high-speed spin coating, followed by a reverse-order cooling annealing process. This not only facilitates the preparation of vertically grown low-dimensional perovskite thin films with multiphase structures but also offers excellent repeatability, reducing the manufacturing cost of the solar cell device. The reverse-order cooling annealing process described in this invention is simple and highly suitable for industrial production.

[0006] Technical solution: This invention provides a method for preparing low-dimensional perovskite thin films, comprising the following steps:

[0007] Step 1: Weigh and mix p-fluorophenylethylamine iodine, iodomethylamine, lead iodide, iodomethylammonium iodide, methylammonium chloride and lead chloride to obtain a mixed powder. Add dimethylformamide and dimethyl sulfoxide to the mixed powder and stir to obtain a low-dimensional perovskite precursor solution.

[0008] Step 2: Drop the low-dimensional perovskite precursor solution onto the substrate, spin-coat it at 5000-6000 rpm for 10-20 seconds, and then perform a reverse cooling annealing treatment to obtain a low-dimensional perovskite film; wherein, the reverse cooling annealing treatment is to first heat at 110-140℃ for 4-10 seconds, and then heat at 70-90℃ for 5-10 minutes.

[0009] Furthermore, in step one, the stoichiometric molar ratio of lead iodide, methylammonium chloride, and lead chloride is 10:1:1;

[0010] And / or, the stoichiometric molar ratio of the p-fluorophenylethylamine iodine, the iodomethylamine, the iodomethylammonium iodide and the lead iodide is 2:0.9(n-1):0.1(n-1):n, where n is the number of octahedral layers in the inorganic layer, and n is a natural number greater than 0 and less than or equal to 10.

[0011] Furthermore, in step one, the concentration of the low-dimensional perovskite precursor solution is 1-1.2 mol / L.

[0012] Furthermore, in step one, the volume ratio of the dimethylformamide and the dimethyl sulfoxide is 95:5.

[0013] Preferably, in step one, the stirring process is performed at room temperature for 3-12 hours.

[0014] The present invention also provides a perovskite solar cell: from bottom to top, it comprises an ITO conductive glass, a hole transport layer, a low-dimensional perovskite thin film, an electron transport layer, a hole blocking layer, and a metal electrode layer, wherein the low-dimensional perovskite thin film is prepared by any of the above methods.

[0015] Furthermore, the hole transport layer is made of NiO. x ;

[0016] And / or, the electron transport layer is made of PCBM;

[0017] And / or, the hole blocking layer is made of BCP;

[0018] And / or, the metal electrode layer is made of either silver or gold, and its thickness is 60-100 nm.

[0019] Preferably, the hole transport layer is further provided with a PTAA modification layer.

[0020] The present invention also provides a method for preparing a perovskite solar cell as described in any of the preceding claims, comprising the following steps:

[0021] Step 1: Perform ultrasonic cleaning on the ITO conductive glass sequentially using cleaning agent, deionized water, and alcohol. Then, treat the cleaned ITO conductive glass with ozone for 15-20 minutes, followed by NiO... x The solution is dropped onto the ozone-treated ITO conductive glass and spin-coated at 4000-5000 rpm for 25-35 seconds. The spin-coated film is then annealed at 230-280℃ for 40-60 minutes to obtain the hole transport layer.

[0022] Step 2: Prepare a low-dimensional perovskite thin film on the hole transport layer;

[0023] Step 3: Drop the PCBM solution onto the low-dimensional perovskite film, spin coat at 2000-3000 rpm for 55-65 seconds, and anneal the spin-coated film at 80-90℃ for 8-12 minutes to obtain the electron transport layer.

[0024] Step 4: Add BCP solution dropwise onto the electron transport layer, spin coat at 3000-4000 rpm for 25-35 seconds, and anneal the spin-coated film at 80-90℃ for 8-12 minutes to obtain the hole blocking layer.

[0025] Step 5: Vacuum thermal evaporation of a metal electrode layer is performed on the hole blocking layer to obtain a perovskite solar cell.

[0026] Furthermore, in step two, a PTAA-modified layer is first prepared on the hole transport layer, and then a low-dimensional perovskite thin film is prepared on the PTAA-modified layer.

[0027] Specifically, a PTAA-modified layer is prepared on the hole transport layer through the following steps:

[0028] The PTAA solution was dropped onto the hole transport layer and spin-coated at 4500-5500 rpm for 55-65 seconds. The spin-coated film was then annealed at 90-110℃ for 8-12 minutes to obtain the PTAA modified layer.

[0029] Beneficial Effects: High temperatures can promote the vertical growth of multiphase structures in low-dimensional perovskites, but sustained high temperatures can damage their crystal structure. This invention employs a reverse-order cooling annealing process, which not only facilitates the preparation of low-dimensional perovskite films with vertically grown multiphase structures but also offers excellent reproducibility, reducing the cost of battery device fabrication. The reverse-order cooling annealing process described in this invention is simple to implement and highly suitable for industrial production. Its specific beneficial effects are as follows:

[0030] (1) The reverse cooling annealing process described in this invention firstly involves rapid spin coating to form a dense wet film; secondly, high-temperature short-time treatment is used to provide a high temperature to form a nucleation point, thereby giving energy for the vertical growth of multiphase structures in the low-dimensional perovskite film; finally, low-temperature long-time treatment is used to promote the growth of low-dimensional perovskite grains and form a dense film.

[0031] (2) This invention optimizes the spin-coating time, controlling it within a certain range, and performs spin-coating at room temperature, eliminating the need for hot spin-coating (which has very poor repeatability). Furthermore, the preparation process of this invention is simple and requires minimal equipment. If the spin-coating time is too short, the low-dimensional perovskite wet film is unstable, and after heating, it will form a very rough surface morphology. This is because the low-dimensional perovskite film has many pores, which is not conducive to the fabrication of photovoltaic devices. If the spin-coating time is too long, the low-dimensional perovskite wet film is stable and has already formed a large number of nucleation sites. After heating, the multiphase structure exhibits a disordered arrangement, resulting in different morphologies in the optical photographs of the low-dimensional perovskite film. Since the disordered multiphase structure is not conducive to carrier transport, the current density of the battery device is too low.

[0032] (3) The reverse cooling annealing process described in this invention can realize low-dimensional perovskite solar cells with a photoelectric conversion efficiency of over 15% and has good repeatability. Attached Figure Description

[0033] Figure 1 This is a SEM image of the low-dimensional perovskite thin film prepared according to Embodiment 1 of the present invention;

[0034] Figure 2 This is a SEM image of the low-dimensional perovskite thin film prepared in Comparative Example 1.

[0035] Figure 3 This is a SEM image of the low-dimensional perovskite thin film prepared in Comparative Example 2.

[0036] Figure 4 The current density-voltage curves are of a solar cell (A) containing the low-dimensional perovskite thin film prepared according to Embodiment 1 of the present invention, a solar cell (B) containing the low-dimensional perovskite thin film prepared according to Comparative Example 1, and a solar cell (C) containing the low-dimensional perovskite thin film prepared according to Comparative Example 2.

[0037] Figure 5 Photoluminescence images of the low-dimensional perovskite film (A) prepared according to Embodiment 1 of the present invention, the low-dimensional perovskite film (B) prepared according to Comparative Example 1, and the low-dimensional perovskite film (C) prepared according to Comparative Example 2.

[0038] Figure 6 The images show time-resolved photoluminescence patterns of the low-dimensional perovskite film (A) prepared according to Embodiment 1 of the present invention, the low-dimensional perovskite film (B) prepared according to Comparative Example 1, and the low-dimensional perovskite film (C) prepared according to Comparative Example 2.

[0039] Figure 7 The X-ray diffraction patterns are of the low-dimensional perovskite film (A) prepared according to Embodiment 1 of the present invention, the low-dimensional perovskite film (B) prepared according to Comparative Example 1, and the low-dimensional perovskite film (C) prepared according to Comparative Example 2.

[0040] Figure 8 It is an optical photograph of the low-dimensional perovskite thin film prepared according to Embodiment 1 of the present invention;

[0041] Figure 9 It is an optical photograph of the low-dimensional perovskite thin film prepared in Comparative Example 3;

[0042] Figure 10 It is an optical photograph of the low-dimensional perovskite thin film prepared in Comparative Example 4. Detailed Implementation

[0043] The present invention will now be described in detail with reference to the accompanying drawings.

[0044] Implementation method 1:

[0045] This embodiment provides a method for preparing low-dimensional perovskite thin films, the specific steps of which are as follows:

[0046] 1) Weigh 0.1471 g (0.55 mol / L) of p-fluorophenylethylamine iodine, 0.1180 g (0.7425 mol / L) of methyl iodine, 0.5071 g (1.1 mol / L) of lead iodide, 0.0142 g (0.0825 mol / L) of formamidinium iodide, 0.0075 g (0.11 mol / L) of methyl ammonium chloride and 0.0306 g (0.11 mol / L) of lead chloride and mix them to obtain a mixed powder. Add 950 μL of dimethylformamide and 50 μL of dimethyl sulfoxide mixed solution to the mixed powder and stir. Stir at room temperature for 6 hours to obtain a low-dimensional perovskite precursor solution.

[0047] 2) The low-dimensional perovskite precursor solution was dropped onto the substrate and spin-coated at 5000 rpm for 16 seconds. Then, it was heated at 120°C for 8 seconds and then at 80°C for 5 minutes.

[0048] This embodiment also provides a perovskite solar cell comprising the low-dimensional perovskite thin film prepared in this embodiment. The perovskite solar cell, from bottom to top, comprises a conductive substrate, a hole transport layer, a low-dimensional perovskite thin film layer, an electron transport layer, a hole blocking layer, and a metal electrode layer. The specific preparation method is as follows:

[0049] 1) The conductive substrate ITO conductive glass was ultrasonically cleaned sequentially with cleaning agent, deionized water, and alcohol. Then, the cleaned ITO conductive glass was ozone treated for 15 minutes. Next, a nickel oxide precursor solution was dropped onto the ozone-treated ITO conductive glass and spin-coated at 4000 rpm for 30 seconds. The spin-coated film was then annealed at 250°C for 40 minutes to obtain NiO. x Hole transport layer;

[0050] 2) Add PTAA solution dropwise to NiO x On the hole transport layer, spin-coat at 5000 rpm for 60 seconds, and anneal the spin-coated film at 100℃ for 10 min to obtain the PTAA modified layer.

[0051] 3) Prepare a low-dimensional perovskite thin film layer on the PTAA-modified layer;

[0052] 4) The PCBM solution was dropped onto the low-dimensional perovskite thin film layer and spin-coated at 2500 rpm for 60 seconds. The spin-coated film was then annealed at 80°C for 10 minutes to obtain the electron transport layer.

[0053] 5) Add BCP solution dropwise onto the electron transport layer, spin coat at 3500 rpm for 30 seconds, and anneal the spin-coated film at 80°C for 10 minutes to obtain the hole blocking layer.

[0054] 6) Vacuum thermal evaporation of 70 nm Ag as a metal electrode layer on the hole blocking layer yields a perovskite solar cell.

[0055] The SEM image of the low-dimensional perovskite thin film prepared in this embodiment is shown below. Figure 1 As shown, optical photographs are as follows Figure 8 As shown.

[0056] Implementation Method 2:

[0057] This embodiment provides a method for preparing low-dimensional perovskite thin films, the specific steps of which are as follows:

[0058] 1) Weigh 0.1471 g (0.55 mol / L) of p-fluorophenylethylamine iodine, 0.1180 g (0.7425 mol / L) of methyl iodine, 0.5071 g (1.1 mol / L) of lead iodide, 0.0142 g (0.0825 mol / L) of formamidinium iodide, 0.0075 g (0.11 mol / L) of methyl ammonium chloride and 0.0306 g (0.11 mol / L) of lead chloride and mix them to obtain a mixed powder. Add 950 μL of dimethylformamide and 50 μL of dimethyl sulfoxide mixed solution to the mixed powder and stir. Stir at room temperature for 6 hours to obtain a low-dimensional perovskite precursor solution.

[0059] 2) The low-dimensional perovskite precursor solution was dropped onto the substrate and spin-coated at 5000 rpm for 16 seconds. Then, it was heated at 140°C for 10 seconds and then at 90°C for 10 minutes.

[0060] The method for preparing a perovskite solar cell containing the low-dimensional perovskite thin film prepared in this embodiment is exactly the same as that in Embodiment 1, and will not be repeated here.

[0061] Implementation Method 3:

[0062] This embodiment provides a method for preparing low-dimensional perovskite thin films, the specific steps of which are as follows:

[0063] 1) Weigh 0.1471 g (0.55 mol / L) of p-fluorophenylethylamine iodine, 0.1180 g (0.7425 mol / L) of methyl iodine, 0.5071 g (1.1 mol / L) of lead iodide, 0.0142 g (0.0825 mol / L) of formamidinium iodide, 0.0075 g (0.11 mol / L) of methyl ammonium chloride and 0.0306 g (0.11 mol / L) of lead chloride and mix them to obtain a mixed powder. Add 950 μL of dimethylformamide and 50 μL of dimethyl sulfoxide mixed solution to the mixed powder and stir. Stir at room temperature for 6 hours to obtain a low-dimensional perovskite precursor solution.

[0064] 2) The low-dimensional perovskite precursor solution was dropped onto the substrate and spin-coated at 5000 rpm for 16 seconds. Then, it was heated at 110°C for 4 seconds and then at 70°C for 6 minutes.

[0065] The method for preparing a perovskite solar cell containing the low-dimensional perovskite thin film prepared in this embodiment is exactly the same as that in Embodiment 1, and will not be repeated here.

[0066] Comparative Example 1:

[0067] This comparative example provides a method for preparing low-dimensional perovskite thin films, the specific steps of which are as follows:

[0068] 1) Weigh 0.1471 g (0.55 mol / L) of p-fluorophenylethylamine iodine, 0.1180 g (0.7425 mol / L) of methyl iodine, 0.5071 g (1.1 mol / L) of lead iodide, 0.0142 g (0.0825 mol / L) of formamidinium iodide, 0.0075 g (0.11 mol / L) of methyl ammonium chloride and 0.0306 g (0.11 mol / L) of lead chloride and mix them to obtain a mixed powder. Add 950 μL of dimethylformamide and 50 μL of dimethyl sulfoxide mixed solution to the mixed powder and stir. Stir at room temperature for 6 hours to obtain a low-dimensional perovskite precursor solution.

[0069] 2) The low-dimensional perovskite precursor solution was dropped onto the substrate, spin-coated at 5000 rpm for 16 seconds, and then heated at 80°C for 5 minutes.

[0070] The method for preparing the perovskite solar cell containing the low-dimensional perovskite thin film prepared in this comparative example is exactly the same as that in Embodiment 1, and will not be repeated here.

[0071] SEM images of the low-dimensional perovskite films prepared in this comparative example are shown below. Figure 2 As shown.

[0072] Comparative Example 2:

[0073] This comparative example provides a method for preparing low-dimensional perovskite thin films, the specific steps of which are as follows:

[0074] 1) Weigh 0.1471 g (0.55 mol / L) of p-fluorophenylethylamine iodine, 0.1180 g (0.7425 mol / L) of methyl iodine, 0.5071 g (1.1 mol / L) of lead iodide, 0.0142 g (0.0825 mol / L) of formamidinium iodide, 0.0075 g (0.11 mol / L) of methyl ammonium chloride and 0.0306 g (0.11 mol / L) of lead chloride and mix them to obtain a mixed powder. Add 950 μL of dimethylformamide and 50 μL of dimethyl sulfoxide mixed solution to the mixed powder and stir. Stir at room temperature for 6 hours to obtain a low-dimensional perovskite precursor solution.

[0075] 2) The low-dimensional perovskite precursor solution was dropped onto the substrate, spin-coated at 5000 rpm for 16 seconds, and then heated at 120°C for 5 minutes.

[0076] The method for preparing the perovskite solar cell containing the low-dimensional perovskite thin film prepared in this comparative example is exactly the same as that in Embodiment 1, and will not be repeated here.

[0077] SEM images of the low-dimensional perovskite films prepared in this comparative example are shown below. Figure 3 As shown.

[0078] Comparative Example 3:

[0079] This comparative example provides a method for preparing low-dimensional perovskite thin films, the specific steps of which are as follows:

[0080] 1) Weigh 0.1471 g (0.55 mol / L) of p-fluorophenylethylamine iodine, 0.1180 g (0.7425 mol / L) of methyl iodine, 0.5071 g (1.1 mol / L) of lead iodide, 0.0142 g (0.0825 mol / L) of formamidinium iodide, 0.0075 g (0.11 mol / L) of methyl ammonium chloride and 0.0306 g (0.11 mol / L) of lead chloride and mix them to obtain a mixed powder. Add 950 μL of dimethylformamide and 50 μL of dimethyl sulfoxide mixed solution to the mixed powder and stir. Stir at room temperature for 6 hours to obtain a low-dimensional perovskite precursor solution.

[0081] 2) The low-dimensional perovskite precursor solution was dropped onto the substrate and spin-coated at 5000 rpm for 5 seconds. Then, it was heated at 120°C for 8 seconds and then at 80°C for 5 minutes.

[0082] The method for preparing the perovskite solar cell containing the low-dimensional perovskite thin film prepared in this comparative example is exactly the same as that in Embodiment 1, and will not be repeated here.

[0083] Optical photographs of the low-dimensional perovskite thin films prepared in this comparative example are shown below. Figure 9 As shown.

[0084] Comparative Example 4:

[0085] This comparative example provides a method for preparing low-dimensional perovskite thin films, the specific steps of which are as follows:

[0086] 1) Weigh 0.1471 g (0.55 mol / L) of p-fluorophenylethylamine iodine, 0.1180 g (0.7425 mol / L) of methyl iodine, 0.5071 g (1.1 mol / L) of lead iodide, 0.0142 g (0.0825 mol / L) of formamidinium iodide, 0.0075 g (0.11 mol / L) of methyl ammonium chloride and 0.0306 g (0.11 mol / L) of lead chloride and mix them to obtain a mixed powder. Add 950 μL of dimethylformamide and 50 μL of dimethyl sulfoxide mixed solution to the mixed powder and stir. Stir at room temperature for 6 hours to obtain a low-dimensional perovskite precursor solution.

[0087] 2) The low-dimensional perovskite precursor solution was dropped onto the substrate and spin-coated at 5000 rpm for 40 seconds. Then, it was heated at 120°C for 8 seconds and then at 80°C for 5 minutes.

[0088] The method for preparing the perovskite solar cell containing the low-dimensional perovskite thin film prepared in this comparative example is exactly the same as that in Embodiment 1, and will not be repeated here.

[0089] Optical photographs of the low-dimensional perovskite thin films prepared in this comparative example are shown below. Figure 10 As shown.

[0090] The performance of solar cells containing the low-dimensional perovskite thin films prepared in Embodiment 1 and Comparative Examples 1-4 was analyzed, and the results are as follows: Figure 1-10 As shown: Implementation method 1 is curve A in the figure, comparative example 1 is curve B in the figure, and comparative example 2 is curve C in the figure. Figure 1 The image shows a SEM image of the low-dimensional perovskite thin film prepared in Embodiment 1, which has a uniform and dense surface. Figure 2 The image shows a SEM image of the low-dimensional perovskite film prepared in Comparative Example 1, which exhibits numerous pinhole morphologies on its surface. Figure 3 The image shows a SEM image of the low-dimensional perovskite film prepared in Comparative Example 2. The surface is not dense and lead iodide precipitation is observed. Figure 4 The current density-voltage curve of a low-dimensional perovskite solar cell can intuitively reflect the photoelectric conversion efficiency of the device. From... Figure 4 As can be seen, the battery device prepared in Implementation Method 1 has the highest photoelectric conversion efficiency, reaching 15.04%. In addition, the battery device prepared in Comparative Example 1 has the second highest photoelectric conversion efficiency, while the battery device prepared in Comparative Example 2 has the lowest photoelectric conversion efficiency. Figure 5 The image shows the photoluminescence (PL) of the low-dimensional perovskite thin film. The low-dimensional perovskite thin film prepared in Example 1 exhibits the strongest PL intensity, followed by the low-dimensional perovskite thin film prepared in Comparative Example 1, and the low-dimensional perovskite thin film prepared in Comparative Example 2 exhibits the lowest PL intensity. This indicates that the low-dimensional perovskite thin film prepared in Example 1 has a low defect density, and non-radiative recombination is effectively suppressed. Figure 6 The image shows the time-resolved photoluminescence (TRPL) pattern of the low-dimensional perovskite thin film. The average fluorescence lifetime of the low-dimensional perovskite thin film prepared in Example 1 is 268.36 ns, the average fluorescence lifetime of the low-dimensional perovskite thin film prepared in Comparative Example 1 is 185.53 ns, and the average fluorescence lifetime of the low-dimensional perovskite thin film prepared in Comparative Example 2 is 143.66 ns. This further demonstrates that the low-dimensional perovskite thin film prepared in Example 1 has a lower defect density, which is beneficial for carrier transport and also for fabricating photovoltaic devices with excellent photovoltaic performance. This is consistent with... Figure 4 The analysis results are consistent. Figure 7 The X-ray diffraction (XRD) pattern of the low-dimensional perovskite thin film can visually reflect its crystal structure. It is evident that the XRD pattern of the low-dimensional perovskite thin film prepared in Example 1 shows no impurity peaks, indicating better crystallinity, which is consistent with... Figure 1 The analysis results are consistent. Figure 8 An optical photograph of the low-dimensional perovskite thin film prepared in Embodiment 1, showing a smooth and dense surface. Figure 9 An optical photograph of the low-dimensional perovskite thin film prepared for Comparative Example 3 shows a very rough surface due to the presence of numerous pores. Figure 10 The images shown are optical photographs of the low-dimensional perovskite thin films prepared in Comparative Example 4. The surface morphology varies because the wet low-dimensional perovskite films are stable and have already formed a large number of nucleation sites. After heating, the multiphase structure exhibits a disordered arrangement. This demonstrates that the prepared low-dimensional perovskite thin films achieve the optimal surface smoothness within the spin-coating time specified in this invention.

[0091] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a low-dimensional perovskite thin film, characterized in that, Includes the following steps: Step 1: Weigh and mix p-fluorophenylethylamine iodine, iodomethylamine, lead iodide, iodomethylammonium iodide, methylammonium chloride and lead chloride to obtain a mixed powder. Add dimethylformamide and dimethyl sulfoxide to the mixed powder and stir to obtain a low-dimensional perovskite precursor solution. Step 2: Drop the low-dimensional perovskite precursor solution onto the substrate, spin-coat it at 5000-6000 rpm for 10-20 seconds, and then perform a reverse cooling annealing treatment to obtain a low-dimensional perovskite film; wherein, the reverse cooling annealing treatment is to first heat at 110-140℃ for 4-10 seconds, and then heat at 70-90℃ for 5-10 minutes.

2. The method for preparing low-dimensional perovskite thin films according to claim 1, characterized in that, In step one, the stoichiometric molar ratio of lead iodide, methylammonium chloride, and lead chloride is 10:1:1; And / or, in step one, the stoichiometric molar ratio of p-fluorophenylethylamine iodine, methyl iodine, methyl iodine and lead iodide is 2:0.9(n-1):0.1(n-1):n, where n is the number of octahedral layers in the inorganic layer, and n is a natural number greater than 0 and less than or equal to 10.

3. The method for preparing low-dimensional perovskite thin films according to claim 1, characterized in that, In step one, the concentration of the low-dimensional perovskite precursor solution is 1-1.2 mol / L.

4. The method for preparing low-dimensional perovskite thin films according to claim 1, characterized in that, In step one, the volume ratio of the dimethylformamide to the dimethyl sulfoxide is 95:

5.

5. The method for preparing low-dimensional perovskite thin films according to claim 1, characterized in that, In step one, the stirring process involves stirring at room temperature for 3-12 hours.

6. A perovskite solar cell, characterized in that: From bottom to top, the structure comprises ITO conductive glass, a hole transport layer, a low-dimensional perovskite thin film, an electron transport layer, a hole blocking layer, and a metal electrode layer, wherein the low-dimensional perovskite thin film is prepared by any one of the methods in claims 1-5.

7. The perovskite solar cell according to claim 6, characterized in that, The hole transport layer is made of nickel oxide thin film, abbreviated as NiO. x film; And / or, the electron transport layer is made of PCBM; And / or, the hole blocking layer is made of BCP; And / or, the metal electrode layer is made of either silver or gold, and its thickness is 60-100 nm.

8. The perovskite solar cell according to claim 6, characterized in that, The hole transport layer is also provided with a PTAA modification layer.

9. A method for preparing a perovskite solar cell as described in any one of claims 6-8, characterized in that, Includes the following steps: Step 1: Perform ultrasonic cleaning on the ITO conductive glass sequentially using cleaning agent, deionized water, and alcohol. Then, treat the cleaned ITO conductive glass with ozone for 15-20 minutes, followed by NiO... x The solution is dropped onto the ozone-treated ITO conductive glass and spin-coated at 4000-5000 rpm for 25-35 seconds. The spin-coated film is then annealed at 230-280℃ for 40-60 minutes to obtain the hole transport layer. Step 2: Prepare a low-dimensional perovskite thin film on the hole transport layer; Step 3: Drop the PCBM solution onto the low-dimensional perovskite film, spin coat at 2000-3000 rpm for 55-65 seconds, and anneal the spin-coated film at 80-90℃ for 8-12 minutes to obtain the electron transport layer. Step 4: Add BCP solution dropwise onto the electron transport layer, spin coat at 3000-4000 rpm for 25-35 seconds, and anneal the spin-coated film at 80-90℃ for 8-12 minutes to obtain the hole blocking layer. Step 5: Vacuum thermal evaporation of a metal electrode layer is performed on the hole blocking layer to obtain a perovskite solar cell.

10. The method for preparing a perovskite solar cell according to claim 9, characterized in that: In step two, a PTAA-modified layer is first prepared on the hole transport layer, and then a low-dimensional perovskite thin film is prepared on the PTAA-modified layer. Specifically, a PTAA-modified layer is prepared on the hole transport layer through the following steps: The PTAA solution was dropped onto the hole transport layer and spin-coated at 4500-5500 rpm for 55-65 seconds. The spin-coated film was then annealed at 90-110℃ for 8-12 minutes to obtain the PTAA modified layer.

Images