A method for preparing a vertical alignment Pb-Sn perovskite thin film at room temperature without anti-solvent and solar cell application thereof

Abstract

This invention discloses a method for preparing vertically oriented Pb-Sn perovskite thin films at room temperature without anti-solvents and its application in solar cells, relating to the field of perovskite solar cell technology. The method involves dissolving a lead-tin perovskite precursor, stannous fluoride, and formamidine acetate in N,N-dimethylformamide solvent in a specific ratio, and stirring until homogeneous to obtain a lead-tin perovskite precursor solution. The lead-tin mixed perovskite precursor solution is then spin-coated onto a hole transport layer substrate using a room-temperature, anti-solvent-free method. Annealing treatment yields a lead-tin perovskite thin film with vertically oriented growth grains. This invention achieves in-situ formation of vertically oriented growth grains at room temperature without anti-solvents, and the ionic liquid atmosphere method employed allows for significant control. The preparation process is simple, easy to operate, highly reproducible, and environmentally friendly. Lead-tin perovskite solar cell devices prepared using this method exhibit excellent photoelectric performance and superior device stability.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, specifically to a method for preparing vertically oriented Pb-Sn perovskite thin films at room temperature without anti-solvents and its application in solar cells. Background Technology

[0002] Faced with severe challenges such as the energy crisis and environmental pollution, the development of new green energy technologies is urgently needed. Perovskite photovoltaics, due to its superior photoelectric properties, low cost, low energy consumption, and wide range of applications, has attracted much attention in recent years. To date, high-efficiency perovskite photovoltaic technology is mainly based on lead (Pb)-based perovskite materials, with the latest photoelectric conversion efficiency (PCE) exceeding 27.3% in 2025. However, Pb-based perovskites, due to their wide band gap (~1.6 eV), struggle to effectively utilize low-energy photons in the solar spectrum, fundamentally limiting further improvements in their photoelectric conversion efficiency. Lead-tin (Pb-Sn) hybrid perovskites, formed by introducing tin (Sn) into perovskite, possess a narrower band gap and can serve as bottom sub-cells, absorbing low-energy photons. They can be used to construct all-perovskite tandem devices, fully utilizing sunlight. Therefore, the development of lead-tin perovskite photoelectric materials is becoming a highly anticipated cutting-edge research direction in this field.

[0003] In recent years, Pb-Sn perovskite photovoltaic technology has developed rapidly; however, the fabrication of efficient and stable narrow-bandgap Pb-Sn perovskite photovoltaic devices still faces significant challenges. On the one hand, Sn... 2+ The introduction of Sn caused the perovskite to crystallize too quickly, resulting in poor film quality and low coverage; and Sn 2+ It is easily oxidized to Sn 4+ First, the high p-type doping of materials leads to increased defect density and shortened carrier lifetime, severely limiting device performance. Second, current laboratory preparation of Pb-Sn perovskite thin films heavily relies on toxic organic solvents and antisolvents, such as DMF, DMSO, chlorobenzene, and toluene, causing environmental pollution. On the one hand, the rapid nucleation promoted by antisolvents results in small film grain size and numerous crystal defects, restricting carrier migration, accelerating internal ion migration and perovskite decomposition, ultimately reducing device efficiency and stability. On the other hand, the film formation process using antisolvents has poor reproducibility and high cost, which is also unfavorable for large-scale production applications.

[0004] Therefore, developing a simple, reproducible, and environmentally friendly method for preparing vertically oriented Pb-Sn perovskite thin films at room temperature without anti-solvents is of great significance for promoting the commercial development and application of lead-tin perovskite photovoltaic devices. Summary of the Invention

[0005] To address the shortcomings of the aforementioned background technologies, this invention primarily focuses on the problems of existing lead-tin perovskite film preparation methods, which require the use of antisolvents, resulting in small grain size, high defect density, and poor stability. It provides a method for preparing vertically oriented Pb-Sn perovskite thin films at room temperature without antisolvents and its application in solar cells. This method achieves in-situ formation of vertically oriented grains at room temperature without antisolvents, and the ionic liquid atmosphere method employed allows for significant control. The preparation process of this invention is simple, easy to operate, highly reproducible, and environmentally friendly. Lead-tin perovskite solar cell devices prepared based on this method exhibit excellent photoelectric performance and superior device stability.

[0006] The first objective of this invention is to provide a method for preparing vertically oriented Pb-Sn perovskite thin films at room temperature without anti-solvent, comprising the following steps: Methylamine iodide, formamidine iodide, cesium iodide, lead iodide, tin iodide, stannous fluoride, and formamidine acetate were dissolved in DMF and mixed evenly to obtain a lead-tin perovskite precursor solution. In an inert environment and in a methylamine acetic acid atmosphere, lead-tin perovskite precursor solution was spin-coated onto a substrate at room temperature. After annealing, a vertically oriented Pb-Sn perovskite thin film was obtained on the substrate.

[0007] Preferably, the molar ratio of methylamine iodide, formamidine amine iodide, cesium iodide, lead iodide, tin iodide, stannous fluoride, and formamidine acetate is approximately 0.3:0.65:0.05:0.5:0.5:(0.025~0.05):(0.4~0.7). The lead-tin perovskite precursor solution was obtained by stirring at 20-35°C until fully dissolved, and its molar concentration was 0.8-2.3 M. In the preparation of lead-tin perovskite precursor solution, after mixing evenly, Sn powder is added, dispersed evenly, allowed to stand, and then filtered using a 0.22 μm polytetrafluoroethylene filter membrane for later use.

[0008] Preferably, the annealing temperature is 100~180℃ for 6~12 min.

[0009] Preferably, the lead-tin perovskite precursor solution is spin-coated onto the substrate at room temperature in an inert environment and in a methylamine acetic acid atmosphere, comprising: when spin-coating the lead-tin perovskite precursor solution onto the substrate in an inert environment, a cavity containing a methylamine acetic acid atmosphere is placed above the spin-coating. The substrate is a hole transport layer.

[0010] Preferably, the cavity containing the methylamine acetic acid atmosphere is formed by placing the methylamine acetic acid inside the cavity and preheating it to 70~90°C, so that the methylamine acetic acid vaporizes and evaporates throughout the cavity.

[0011] The second objective of this invention is to provide a vertically oriented Pb-Sn perovskite thin film.

[0012] The third objective of this invention is to provide an application of vertically oriented Pb-Sn perovskite thin films in solar cells.

[0013] The fourth objective of this invention is to provide a solar cell comprising, in sequence, an ITO conductive glass, a hole transport layer, a light absorption layer, an electron transport layer, an interface modification layer, and a metal back electrode. The light-absorbing layer is a vertically oriented Pb-Sn perovskite thin film. The hole transport layer is formed by sequentially spin-coating PEDOT:PSS solution and / or NiO onto ITO conductive glass. x Prepared from solution; The electron transport layer is a PCBM; The interface modification layer is BCP; The metal back electrode is Ag; The PEDOT:PSS solution is a solution modified with potassium citrate.

[0014] The fifth objective of this invention is to provide a method for preparing a solar cell, comprising the following steps: Preparation of lead-tin perovskite precursor solution; The ITO conductive glass is cleaned, dried, and subjected to UV-ozone surface treatment, then a hole transport layer is spin-coated and annealed. In an inert environment and in a methylamine acetic acid atmosphere, lead-tin perovskite precursor solution was spin-coated onto the hole transport layer at room temperature, and annealed after film formation to obtain a vertically oriented Pb-Sn perovskite thin film. Electron transport layer fabricated on vertically oriented Pb-Sn perovskite thin film; An interface modification layer and a metal back electrode are vacuum-deposited on the electron transport layer.

[0015] Preferably, when preparing a vertically oriented Pb-Sn perovskite thin film on the hole transport layer, a buried interface solution is first spin-coated onto the hole transport layer. When preparing an electron transport layer on a vertically oriented Pb-Sn perovskite film, an interface solution is first spin-coated onto the vertically oriented Pb-Sn perovskite film. The buried interface solution is prepared by uniformly dispersing F-PEAI, PbI2, Pb(SCN)2, NH4SCN and glycine ethyl hydrochloride in a mixed solution of DMSO and DMF, and preparing a solution with a concentration of 0.01~0.03 mol / L. The upper interface solution is prepared by dissolving EDAI2 and EDACl2 in a mixed solution of IPA and TL to obtain a solution with a concentration of 0.2~0.7 mg / ml.

[0016] Compared with existing technologies, this invention provides a method for preparing vertically oriented Pb-Sn perovskite thin films at room temperature without anti-solvents and its application in solar cells, which has the following significant advantages: (1) This invention is for lead-tin perovskite with small grain size, high defect density and low carrier mobility, and can prepare vertically oriented lead-tin perovskite at room temperature without anti-solvent.

[0017] (2) The MAAc atmosphere method used in this invention can effectively play a regulatory role in promoting the in-situ formation of grains with vertical orientation growth.

[0018] (3) Under optimal process conditions, the lead-tin perovskite solar cell thin film of this invention exhibits good stability, with the corresponding battery device achieving a photoelectric conversion efficiency >21%. After continuous output at maximum power for more than 10 minutes, the output power shows virtually no attenuation. For example... Figure 9 After being placed in a nitrogen environment for 1600 hours, the device efficiency can still maintain more than 95% of the initial efficiency.

[0019] (4) The lead-tin perovskite solar cell thin film and device used in this invention are simple, easy to operate, highly repeatable and environmentally friendly. They can be used to prepare all-perovskite tandem solar cells, which is of great significance for breaking through the SQ limit. Attached Figure Description

[0020] Figure 1 This is a flowchart of the preparation of lead-tin perovskite thin films at room temperature in a nitrogen environment, as shown in Examples 2-4. Figure 2 These are graphs showing the crystal growth of the precursor solution over time under an optical microscope under the conditions of Examples 1 and 2. Figure 3 Comparative diagrams of lead-tin perovskite thin film structures in Comparative Example 1 and Examples 3 and 4; Figure 4 These are morphological images of the upper and lower surface cross-sections of the lead-tin perovskite thin films prepared in Comparative Example 1 and Examples 3 and 4. Figure 5 The XRD patterns are of the lead-tin perovskite thin films prepared in Comparative Example 1 and Examples 1-4. Figure 6 The images show the AFM and KPFM patterns of the lead-tin perovskite thin films prepared in Comparative Example 1 and Examples 3 and 4. Figure 7 Here are the cross-sectional SEM images and structural schematic diagrams of the lead-tin perovskite device prepared in Example 4; Figure 8 The JV curves are for the lead-tin perovskite solar cells prepared in Comparative Example 1 and Example 4. Figure 9The curves show the photoelectric conversion efficiency of the lead-tin perovskite solar cells prepared in Comparative Example 1 and Example 4 under nitrogen atmosphere as a function of time. Detailed Implementation

[0021] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0022] The purpose of this invention is to overcome the problems of existing methods that require antisolvents for lead-tin perovskite film formation, resulting in small grain size, high defect density, and poor stability. This invention provides a room-temperature, solvent-free method for preparing vertically oriented Pb-Sn perovskite thin films and devices. In this invention, a lead-tin perovskite precursor, stannous fluoride, and formamidinium acetate are dissolved in N,N-dimethylformamide solvent in a specific ratio and stirred until homogeneous to obtain a lead-tin perovskite precursor solution. The lead-tin mixed perovskite precursor solution is then spin-coated onto a hole transport layer substrate using a room-temperature, solvent-free method. Annealing treatment yields a lead-tin perovskite thin film with vertically oriented grains. This invention achieves in-situ formation of vertically oriented grains at room temperature without antisolvents, and the ionic liquid atmosphere method allows for significant control. The preparation process is simple, easy to operate, highly reproducible, and environmentally friendly. Lead-tin perovskite solar cell devices prepared using this method exhibit excellent photoelectric performance and superior device stability.

[0023] To achieve the above objectives, a first aspect of the present invention provides a method for preparing vertically oriented Pb-Sn perovskite thin films at room temperature without anti-solvent, comprising the following steps: Methylamine iodide (MAI), formamidine iodide (FAI), cesium iodide (CsI), lead iodide (PbI2), tin iodide (SnI2), stannous fluoride (SnF2), and formamidine acetate (FAAc) were dissolved in DMF and mixed evenly to obtain a lead-tin perovskite precursor solution. In an inert environment and in a methylamine acetic acid (MAAc) atmosphere, lead-tin perovskite precursor solution was spin-coated onto a substrate at room temperature. After annealing, a vertically oriented Pb-Sn perovskite thin film was obtained on the substrate.

[0024] The molar ratio of methylamine iodide, formamidine amine iodide, cesium iodide, lead iodide, tin iodide, stannous fluoride, and formamidine acetate is approximately 0.3:0.65:0.05:0.5:0.5:(0.025~0.05):(0.4~0.7). The lead-tin perovskite precursor solution was obtained by stirring at 20-35°C until fully dissolved, and its molar concentration was 0.8-2.3 M. In the preparation of the lead-tin perovskite precursor solution, after thorough mixing, Sn powder was added, dispersed evenly, allowed to stand, and then filtered through a 0.22 μm polytetrafluoroethylene (PTFE) membrane for later use. Sn powder was added before filtration to prevent the oxidation of divalent Sn.

[0025] The annealing temperature is 100~180℃ for 6~12 min.

[0026] In an inert environment and in a methylamine acetic acid atmosphere, a lead-tin perovskite precursor solution is spin-coated onto a substrate at room temperature, including: when spin-coating the lead-tin perovskite precursor solution onto the substrate in an inert environment, a cavity containing a methylamine acetic acid atmosphere is placed above the spin-coating. The substrate is a hole transport layer.

[0027] The cavity containing the methylamine acetic acid atmosphere is formed by placing the methylamine acetic acid inside the cavity and preheating it to 70~90°C, so that the methylamine acetic acid vaporizes and evaporates throughout the cavity.

[0028] This invention controls spontaneous crystallization by introducing a methylamine acetic acid atmosphere at the top interface and a two-dimensional perovskite at the bottom interface. The methylamine acetic acid atmosphere hinders the nucleation of Pb-Sn crystals and induces their vertical growth, while the two-dimensional perovskite seeds provide uniform nucleation sites, promoting the vertical orientation growth of the Pb-Sn film.

[0029] A second aspect of the present invention provides a vertically oriented Pb-Sn perovskite thin film.

[0030] A third aspect of the present invention provides an application of a vertically oriented Pb-Sn perovskite thin film in a solar cell.

[0031] A fourth aspect of the present invention provides a solar cell comprising, in sequence, an ITO conductive glass, a hole transport layer, a light absorption layer, an electron transport layer, an interface modification layer, and a metal back electrode. The light-absorbing layer is the aforementioned vertically oriented Pb-Sn perovskite thin film. The hole transport layer (HTL) is formed by spin-coating PEDOT:PSS solution and / or NiO onto ITO conductive glass. x Prepared from solution; The electron transport layer is a PCBM; The interface modification layer is BCP; The metal back electrode is Ag; The PEDOT:PSS solution is a solution modified with potassium citrate.

[0032] The fifth aspect of this invention provides a method for preparing a solar cell, comprising the following steps: Preparation of lead-tin perovskite precursor solution; The ITO conductive glass is cleaned, dried, and subjected to UV-ozone surface treatment, then a hole transport layer is spin-coated and annealed. In an inert environment and in a methylamine acetic acid atmosphere, lead-tin perovskite precursor solution was spin-coated onto the hole transport layer at room temperature, and annealed after film formation to obtain a vertically oriented Pb-Sn perovskite thin film. Electron transport layer fabricated on vertically oriented Pb-Sn perovskite thin film; An interface modification layer and a metal back electrode are vacuum-deposited on the electron transport layer.

[0033] When preparing vertically oriented Pb-Sn perovskite films on hole transport layers, a buried interface solution is first spin-coated onto the hole transport layers. When preparing an electron transport layer on a vertically oriented Pb-Sn perovskite film, an interface solution is first spin-coated onto the vertically oriented Pb-Sn perovskite film. The buried interface solution is prepared by uniformly dispersing F-PEAI, PbI2, Pb(SCN)2, NH4SCN and glycine ethyl hydrochloride in a mixed solution of DMSO and DMF, and preparing a solution with a concentration of 0.01~0.03 mol / L. The upper interface solution is prepared by dissolving EDAI2 and EDACl2 in a mixed solution of IPA and TL to obtain a solution with a concentration of 0.2~0.7 mg / ml.

[0034] An exemplary method for fabricating a solar cell includes: (1) Preparation of precursor solution: MAI, FAI, C S I, PbI2 and SnI2 and SnF2 powder were added together to DMF solvent and stirred at room temperature for 1 h until fully dissolved. Then FAAc powder was added to the solution and stirred for another 1 h until fully dissolved to obtain a stable and homogeneous lead-tin perovskite precursor solution with a molar concentration of 0.8~2.3 M. MAI, FAI, C in the precursor solution S The molar ratio of I, PbI2, SnI2 and additives SnF2 and FAAc is approximately 0.3:0.65:0.05:0.5:0.5:0.025~0.05:0.4~0.7.

[0035] (2) Preparation of the buried interface solution: F-PEAI, PbI2, Pb(SCN)2, NH4SCN and GEE powder are added together to a mixed solvent of DMSO and DMF with a volume ratio of 1:3. The mixture is stirred at room temperature until all components are completely dissolved. The molar concentration of the buried interface solution is 0.01~0.05 M. The molar ratio of F-PEAI, PbI2, Pb(SCN)2, NH4SCN and GEE in the subsurface interface solution is approximately 4~8:1:1:0.6~0.9.

[0036] (3) Preparation of the upper interface solution: Dissolve EDAI2 and EDACl2 in a mixed solvent of IPA and TL in a volume ratio of 1:1, and stir at room temperature until all components are completely dissolved. The molar concentration of the upper interface solution is 0.4~0.7 M; the mass ratio of EDAI2 and EDACl2 in the upper interface solution is 4:1.

[0037] The solutions described in steps (1), (2), and (3) are stirred at 20-35°C and 600 rpm to ensure complete dissolution.

[0038] (4) Preparation of modified PEDOT: PSS solution: Potassium citrate powder was added to the original PEDOT: PSS solution, the concentration of potassium citrate in the solution was 3~7 mg / ml, and after stirring for 2 h, it was diluted and stirred for another 2 h to obtain the modified PEDOT: PSS solution; wherein, the dilution ratio of the modified PEDOT: PSS solution to deionized water was 1:8~9.5; The PEDOT:PSS stock solution used in the examples was purchased, model Al4083, and manufactured by Heraeus, Germany.

[0039] (5) NiO x Solution preparation: NiO x The powder was dissolved in deionized water, sonicated for 8 minutes to achieve uniform dispersion, and then filtered using a filter head to obtain NiO. x The solution is ready for use, the NiO x The concentration of the solution is 3~10 mg / ml; (6) A hole transport material is spin-coated onto the cleaned and surface-treated ITO conductive glass. The hole transport layer is the solution obtained in steps (4) and (5). After spin-coating, the solution is annealed at 120°C for 15 min. The hole transport layer was prepared using modified PEDOT:PSS solution and NiO. x In an air environment, 45 μL of modified PEDOT:PSS solution was dropped onto an ITO conductive glass treated with UV ozone. The solution was then spin-coated at 4000 rpm for 30 s, annealed at 120°C for 15 min, and after cooling, NiO was added dropwise. x 60 μL of solution was spin-coated at 2000 rpm for 30 s and then annealed at 120℃ for 15 min.

[0040] (7) Under N2 environment, the buried interface solution is spin-coated at room temperature on the hole transport layer obtained in step (6) and annealed at 100°C for 10 min to provide uniform nucleation sites for crystal growth. For the embedded interface solution, under nitrogen atmosphere, spin-coating at room temperature, cooling the prepared HTL layer of ITO to room temperature, adding 33 μL of the embedded interface solution to the double HTL, spin-coating at 5000 rpm for 45 s, and annealing at 100℃ for 10 min.

[0041] (8) Preheating the ionic liquid (MAAc) generates a MAAc atmosphere; To prepare the MAAc atmosphere, apply MAAc to the bottom and sides of a petri dish, cover it, and preheat the petri dish to 80°C to allow the MAAc to vaporize and evaporate into the dish. During spin coating, place the petri dish with the prepared atmosphere on top of the spin coater to achieve the solvent atmosphere conditions.

[0042] (9) After filtering the lead-tin perovskite precursor solution obtained in step (1) with a 0.22 μm polytetrafluoroethylene filter membrane, the precursor solution was added to the substrate obtained in step (7) under the atmosphere formed in step (8) for room temperature spin coating and annealing at 100°C for 10 min to prepare a dense and vertically oriented perovskite functional layer. The lead-tin perovskite layer was prepared using a room-temperature precursor solution. Under nitrogen atmosphere, the prepared buried interface ITO was cooled to room temperature, and 60 μL of perovskite precursor solution was added dropwise. The mixture was then spin-coated at 1000 rpm for 5 s and 6000 rpm for 40 s. A MAAc atmosphere was applied from the 10th to the 20th s after spin-coating, and the mixture was annealed at 150℃ for 7 min.

[0043] (10) Spin-coating the upper interface solution obtained in step (3) onto the lead-tin perovskite layer; After the prepared perovskite ITO substrate has been fully cooled to room temperature, 33 µL of the upper interface solution is added dropwise, and the substrate is spin-coated at 3000 rpm for 30 s, followed by annealing at 100℃ for 4 min to reduce the roughness of the upper interface.

[0044] (11) Spin-coat an electron transport layer on the upper interface obtained in step (10), wherein the electron transport layer is a PCBM; The electron transport layer was prepared on the upper interface obtained in step (10) by dissolving PCBM in chlorobenzene (CB) at a concentration of 15~20 mg / mL and spin-coating at 1000 rpm for 60s and 2000 rpm for 3s.

[0045] (12) Based on this electron transport layer, vacuum thermal evaporation interface modification layer BCP and metal back electrode Ag are deposited.

[0046] The interface modification layer is selected as 2,9-dimethyl-4,7-diphenyl-1,10-o-phenanthroline (BCP), and the metal back electrode is Ag. Specific steps include: BCP was vacuum thermally deposited onto the composite electron transport layer, with a thickness of approximately 6 nm.

[0047] The thickness of the Ag metal back electrode is approximately 100 nm.

[0048] The core difference between this invention's perovskite solar cells and traditional solar cells lies in the fact that this invention uses room-temperature, solvent-free anti-reverse solvents to prepare vertically oriented lead-tin perovskite thin films. Furthermore, the MAAc atmosphere method used in the preparation process effectively regulates the in-situ formation of grains that promote vertical orientation growth. Most importantly, the preparation process is simple, easy to operate, highly reproducible, and environmentally friendly, enabling the fabrication of all-perovskite tandem solar cells, which is of great significance for overcoming the SQ (short-terminal) limit.

[0049] It should be noted that, unless otherwise specified, the experimental methods used in this invention are all conventional methods; and the reagents and materials used, unless otherwise specified, are all commercially available.

[0050] Example 1 Preparation of FA 0.65 MA 0.3 Cs 0.05 Pb 0.5 Sn 0.5 Methods for using I3 perovskite thin films and their solar cells: Step 1) Weigh out 95.4 mg MAI, 206.6 mg FAI, and 26.0 mg C. S 1. 461.0 mg PbI2 and 372.6 mg SnI2, along with 15.6 mg SnF2, were added to 1 mL of DMF solvent and stirred at room temperature for 1 h until fully dissolved. Then, 125.0 mg FAAc was added to the solution, and stirring was continued for 1 h until fully dissolved to obtain homogeneous and stable FA. 0.65 MA 0.3 Cs 0.05 Pb 0.5 Sn 0.5 The I3 precursor solution, with a molar concentration of 2.0 mmol / mL, was prepared by adding 30.0 mg of Sn powder before filtration to prevent the oxidation of divalent Sn. The solution was stirred for 10 min, allowed to stand, and then filtered through a 0.22 μm polytetrafluoroethylene filter membrane for later use.

[0051] Step 2) The ITO conductive glass is ultrasonically cleaned for 15 minutes each with ethanol, deionized water solution with cleaning agent, deionized water, acetone and ethanol, then dried with nitrogen and placed in an oven at 100℃ for more than 30 minutes for later use.

[0052] Step 3) The dried ITO conductive glass from step 2) is surface treated with an ultraviolet ozone cleaner for 15 minutes.

[0053] Step 4) In an air environment, take 45 μL of PEDOT:PSS solution and drop it onto the ITO conductive glass treated in the above steps. Spin coat it at 5000 rpm for 50 s, and then transfer it to a 150℃ hot plate for annealing for 15 min. In this embodiment, the PEDOT:PSS solution used is a solution that has not been modified by potassium citrate. The PEDOT:PSS solution is prepared by diluting the original PEDOT:PSS solution with deionized water at a ratio of 1:8.

[0054] Step 5) Take 60 μL of the perovskite precursor solution prepared in Step 1) and add it dropwise to the HTL obtained in Step 4). Spin coat at 1000 rpm for 5 s and 6000 rpm for 40 s. After spin coating, quickly transfer it to a hot plate at 150℃ for annealing for 7 min.

[0055] Step 6) Take 40 μL of pre-prepared 18 mg / ml PCBM chlorobenzene solution and drop it onto the perovskite film in step 5). Spin coat at 1000 rpm for 60 s, then spin coat at 2000 rpm for 3 s to complete the preparation of the electron transport layer.

[0056] Step 7) Transfer the substrate obtained in Step 6) to a vacuum evaporation glove box, and use a high vacuum evaporation apparatus to deposit approximately 6 nm BCP and approximately 100 nm Ag electrodes on the electron transport layer to complete the fabrication of the perovskite solar cell device.

[0057] Example 2 See Figure 1 As shown, FA is prepared 0.65 MA 0.3 Cs 0.05 Pb 0.5 Sn 0.5 Methods for using I3 perovskite thin films and their solar cells: Step 1) Weigh out 95.4 mg MAI, 206.6 mg FAI, and 26.0 mg C. S 1. 461.0 mg PbI2 and 372.6 mg SnI2, along with 15.6 mg SnF2, were added to 1 mL of DMF solvent and stirred at room temperature for 1 h until fully dissolved. Then, 125.0 mg FAAc was added to the solution, and stirring was continued for 1 h until fully dissolved to obtain homogeneous and stable FA. 0.65 MA 0.3 Cs 0.05 Pb 0.5 Sn0.5 The I3 precursor solution, with a molar concentration of 2.0 mmol / mL, was prepared by adding 30.0 mg of Sn powder before filtration to prevent the oxidation of divalent Sn. The solution was stirred for 10 min, allowed to stand, and then filtered through a 0.22 μm polytetrafluoroethylene filter membrane for later use.

[0058] Step 2) Weigh 0.8 mg EDAI2 and 0.2 mg EDACl2 and dissolve them in a mixed solution of IPA and TL in a volume ratio of 1:1 to prepare an upper interface solution with a concentration of 0.5 mg / ml. Stir thoroughly at room temperature until all components are dissolved and set aside for later use.

[0059] Step 5) After ultrasonically cleaning the ITO conductive glass with ethanol, deionized water solution with cleaning agent, deionized water, acetone and ethanol for 15 min each, blow the surface with nitrogen and put it in an oven at 100℃ for more than 30 min for later use.

[0060] Step 6) Perform surface treatment on the dried ITO conductive glass from step 5) using an ultraviolet ozone cleaner for 15 minutes.

[0061] Step 7) In an air environment, take 45 μL of PEDOT:PSS solution and drop it onto the ITO conductive glass treated in the above steps. Spin coat at 5000 rpm for 50 s, then transfer it to a 150℃ hot plate and anneal for 15 min. In this embodiment, the PEDOT:PSS solution used is a solution that has not been modified by potassium citrate. The PEDOT:PSS solution is prepared according to the dilution ratio of the original PEDOT:PSS solution to deionized water of 1:9.5.

[0062] Step 8) Coat the bottom and sides of the culture dish with MAAc, cover it, and preheat the culture dish to 80°C to allow the MAAc to vaporize and evaporate into the culture dish. During spin coating, place the culture dish lid with an atmosphere above the spin coater to achieve solvent atmosphere conditions. Take 60 μL of the perovskite precursor solution prepared in Step 1) and add it dropwise to the HTL obtained in Step 7). Under solvent atmosphere conditions, spin coat at 1000 rpm for 5 s and 6000 rpm for 40 s. After spin coating, quickly transfer the mixture to a 150°C hot plate for annealing for 7 min.

[0063] Step 9) After the prepared perovskite ITO substrate has been fully cooled to room temperature, 33 µL of the upper interface solution is added dropwise, and the substrate is spin-coated at 3000 rpm for 30 s. Then, it is placed on a hot plate at 100°C for annealing for 4 min. Step 10) Take 40 μL of pre-prepared 18 mg / ml PCBM chlorobenzene solution and drop it onto the perovskite film in step 9). Spin coat at 1000 rpm for 60 s, then spin coat at 2000 rpm for 3 s to complete the preparation of the electron transport layer.

[0064] Step 11) Transfer the substrate obtained in step 10) to a vacuum evaporation glove box, and use a high vacuum evaporation apparatus to deposit approximately 6 nm BCP and approximately 100 nm Ag electrodes on the electron transport layer to complete the fabrication of the perovskite solar cell device.

[0065] Example 3 See Figure 1 As shown, FA is prepared 0.65 MA 0.3 Cs 0.05 Pb 0.5 Sn 0.5 Methods for using I3 perovskite thin films and their solar cells: Step 1) Weigh out 95.4 mg MAI, 206.6 mg FAI, and 26.0 mg C. S 1. 461.0 mg PbI2 and 372.6 mg SnI2, along with 15.6 mg SnF2, were added to 1 mL of DMF solvent and stirred at room temperature for 1 h until fully dissolved. Then, 125.0 mg FAAc was added to the solution, and stirring was continued for 1 h until fully dissolved to obtain homogeneous and stable FA. 0.65 MA 0.3 Cs 0.05 Pb 0.5 Sn 0.5 The I3 precursor solution, with a molar concentration of 2.0 mmol / mL, was mixed with 30.0 mg Sn powder before filtration, stirred for 10 min, allowed to stand, and then filtered through a 0.22 μm polytetrafluoroethylene filter membrane for later use.

[0066] Step 2) Weigh 0.8 mg EDAI2 and 0.2 mg EDACl2 and dissolve them in a mixed solution of IPA and TL in a volume ratio of 1:1 to prepare an upper interface solution with a concentration of 0.5 mg / ml. Stir thoroughly at room temperature until all components are dissolved and set aside for later use.

[0067] Step 3) Weigh 5.0 mg of potassium citrate and dissolve it in 1 mL of PEDOT: PSS stock solution. Stir thoroughly for 2 h, then dilute at a ratio of 1:9. Continue stirring for 2 h, filter, and refrigerate for later use to obtain modified PEDOT: PSS solution.

[0068] Step 4) Weigh 5.0 mg NiO xDissolve in 1 mL of deionized water, sonicate for 8 min to disperse evenly, filter with a filter head and use for later use.

[0069] Step 5) After ultrasonically cleaning the ITO conductive glass with ethanol, deionized water solution with cleaning agent, deionized water, acetone and ethanol for 15 min each, blow the surface with nitrogen and put it in an oven at 100℃ for more than 30 min for later use.

[0070] Step 6) Perform surface treatment on the dried ITO conductive glass from step 5) using an ultraviolet ozone cleaner for 15 minutes.

[0071] Step 7) In an air environment, drop 45 μL of the modified PEDOT:PSS solution onto the ITO conductive glass treated in the above steps, spin-coat at 4000 rpm for 30 s, then transfer to a 120℃ hot plate and anneal for 15 min. After cooling, take the freshly prepared NiO... x 60 μL of the solution was dropped onto the annealed ITO conductive glass and spin-coated at 2000 rpm for 30 s. Then it was transferred to a hot plate at 120℃ and annealed for 15 min.

[0072] Step 8) Coat the bottom and sides of the culture dish with MAAc, cover it, and preheat the culture dish to 80°C to allow the MAAc to vaporize and evaporate into the culture dish. During spin coating, place the culture dish lid with an atmosphere above the spin coating to achieve solvent atmosphere conditions. Take 60 μL of the perovskite precursor solution prepared in Step 1) and add it dropwise to the HTL obtained in Step 7). Under solvent atmosphere conditions, spin coat at 1000 rpm for 5 s and 6000 rpm for 40 s. After spin coating, quickly transfer it to a 150°C hot plate for annealing for 7 min to obtain a lead-tin perovskite film.

[0073] Step 9) After the prepared perovskite ITO substrate is fully cooled to room temperature, 33 µL of the upper interface solution is added dropwise, and the substrate is spin-coated at 3000 rpm for 30 s. Then, it is placed on a hot plate at 100°C for annealing for 4 min.

[0074] Step 10) Take 40 μL of pre-prepared 18 mg / ml PCBM chlorobenzene solution and drop it onto the perovskite film in step 9). Spin coat at 1000 rpm for 60 s, then spin coat at 2000 rpm for 3 s to complete the preparation of the electron transport layer.

[0075] Step 11) Transfer the substrate obtained in step 10) to a vacuum evaporation glove box, and use a high vacuum evaporation apparatus to deposit approximately 6 nm BCP and approximately 100 nm Ag electrodes on the electron transport layer to complete the fabrication of the perovskite solar cell device.

[0076] Example 4 See Figure 1 As shown, FA is prepared 0.65 MA 0.3 Cs 0.05 Pb 0.5 Sn 0.5 Methods for using I3 perovskite thin films and their solar cells: Step 1) Weigh out 95.4 mg MAI, 206.6 mg FAI, and 26.0 mg C. S 1. 461.0 mg PbI2 and 372.6 mg SnI2, along with 15.6 mg SnF2, were added to 1 mL of DMF solvent and stirred at room temperature for 1 h until fully dissolved. Then, 125.0 mg FAAc was added to the solution, and stirring was continued for 1 h until fully dissolved to obtain homogeneous and stable FA. 0.65 MA 0.3 Cs 0.05 Pb 0.5 Sn 0.5 The I3 precursor solution, with a molar concentration of 2.0 mmol / mL, was mixed with 30.0 mg Sn powder before filtration, stirred for 10 min, allowed to stand, and then filtered through a 0.22 μm polytetrafluoroethylene filter membrane for later use.

[0077] Step 2) Weigh 28.1 mg F-PEAI, 9.2 mg PbI2, 6.6 mg Pb(SCN)2, 1.6 mg NH4SCN and 2.0 mg glycine ethyl hydrochloride (GEE) into a mixed solution of DMSO and DMF in a volume ratio of 1:3, prepare a 0.02 mol / L subsurface interface solution, stir thoroughly at room temperature until all components are dissolved, and set aside for later use.

[0078] Step 3) Weigh 0.8 mg EDAI2 and 0.2 mg EDACl2 and dissolve them in a mixed solution of IPA and TL in a volume ratio of 1:1 to prepare an upper interface solution with a concentration of 0.5 mg / ml. Stir thoroughly at room temperature until all components are dissolved and set aside for later use.

[0079] Step 4) Weigh 5.0 mg of potassium citrate and dissolve it in 1 mL of PEDOT: PSS stock solution. Stir thoroughly for 2 h, then dilute at a ratio of 1:9. Continue stirring for 2 h, filter, and refrigerate for later use to obtain modified PEDOT: PSS solution.

[0080] Step 5) Weigh 5.0 mg NiO x Dissolve in 1 mL of deionized water, sonicate for 8 min to disperse evenly, filter with a filter head and use for later use.

[0081] Step 6) After ultrasonically cleaning the ITO conductive glass with ethanol, deionized water solution with cleaning agent, deionized water, acetone and ethanol for 15 min each, blow the surface with nitrogen and put it in an oven at 100℃ for more than 30 min for later use.

[0082] Step 7) Perform surface treatment on the dried ITO conductive glass from step 6) using an ultraviolet ozone cleaner for 15 minutes.

[0083] Step 8) In an air environment, drop 45 μL of the modified PEDOT:PSS solution onto the ITO conductive glass treated in the above steps, spin-coat at 4000 rpm for 30 s, then transfer to a 120℃ hot plate and anneal for 15 min. After cooling, pick up the freshly prepared NiO... x 60 μL of the solution was dropped onto the annealed ITO conductive glass and spin-coated at 2000 rpm for 30 s. Then it was transferred to a hot plate at 120℃ and annealed for 15 min.

[0084] Step 9) Transfer the annealed substrate from Step 8) to a glove box and cool it to room temperature. Add 33 μL of the prepared embedded interface solution to the dual HTL and spin coat at 5000 rpm for 45 s. After spin coating, quickly transfer it to a 100℃ hot plate for annealing for 10 min.

[0085] Step 10) Coat the bottom and sides of the culture dish with MAAc, cover it, and preheat the culture dish to 80°C to allow the MAAc to vaporize and evaporate into the culture dish. During spin coating, place the culture dish lid with an atmosphere above the spin coating to achieve solvent atmosphere conditions. Take 60 μL of the perovskite precursor solution prepared in Step 1) and add it dropwise to the embedded interface obtained in Step 9). Under solvent atmosphere conditions, spin coat at 1000 rpm for 5 s and 6000 rpm for 40 s. After spin coating, quickly transfer it to a 150°C hot plate for annealing for 7 min to obtain a lead-tin perovskite film, as shown below. Figure 4 As shown, in Comparative Example 1, the perovskite grains are small and arbitrarily oriented, resulting in a thin film with numerous defects both on the surface and inside, and very obvious grain boundaries, which severely hinders carrier extraction and transport. In Example 3, the perovskite grains are smaller and exhibit a dense arrangement, especially at the lower interface, where the density and smoothness are significantly improved, indicating that NiO... xModifying the PEDOT:PSS layer improved the bottom interface contact of the film. Defects in the film were suppressed to some extent, but the grain orientation remained irregular, which was detrimental to carrier transport. In contrast, the perovskite in Example 4 exhibited uniform crystallization, larger and denser grains, and fewer film defects. More importantly, the crystals showed highly consistent out-of-plane orientation growth, with a highly ordered arrangement and a through-crystal mode. This structure effectively reduced grain boundary scattering and transport barriers, thereby significantly improving the migration and collection efficiency of carriers in the vertical direction. Figure 5 In the XRD pattern, the application of the atmosphere effect and the modification of the buried interface both significantly increased the intensity of the characteristic diffraction peaks, indicating a further improvement in the crystallinity of the film. To further verify the smoothness of the lead-tin perovskite film surface, AFM was used for characterization. The results showed that, overall, the application of the atmosphere effect and the modification of the buried interface resulted in a relatively smoother film surface.

[0086] Step 11) After the prepared perovskite ITO substrate is fully cooled to room temperature, 33 µL of the upper interface solution is added dropwise, and the substrate is spin-coated at 3000 rpm for 30 s. Then, it is placed on a hot plate at 100°C for annealing for 4 min.

[0087] Step 12) Take 40 μL of pre-prepared 18 mg / ml PCBM chlorobenzene solution and drop it onto the perovskite film in step 11). Spin coat at 1000 rpm for 60 s, then spin coat at 2000 rpm for 3 s to complete the preparation of the electron transport layer.

[0088] Step 13) Transfer the substrate obtained in Step 12) to a vacuum evaporation glove box, and use a high vacuum evaporation apparatus to deposit approximately 6 nm BCP and approximately 100 nm Ag electrodes on the electron transport layer to complete the fabrication of the perovskite solar cell device.

[0089] Comparative Example 1 Preparation of FA 0.65 MA 0.3 Cs 0.05 Pb 0.5 Sn 0.5 Methods for using I3 perovskite thin films and their solar cells: Step 1) Weigh out 95.4 mg MAI, 206.6 mg FAI, and 26.0 mg C. S 1. 461.0 mg PbI2 and 372.6 mg SnI2, along with 15.6 mg SnF2, were added to 1 mL of DMF solvent and stirred at room temperature for 1 h until fully dissolved. Then, 125.0 mg FAAc was added to the solution, and stirring was continued for 1 h until fully dissolved to obtain homogeneous and stable FA. 0.65 MA 0.3 Cs0.05 Pb 0.5 Sn 0.5 The I3 precursor solution, with a molar concentration of 2.0 mmol / mL, was mixed with 30.0 mg Sn powder before filtration, stirred for 10 min, allowed to stand, and then filtered through a 0.22 μm polytetrafluoroethylene filter membrane for later use.

[0090] Step 2) Weigh 5.0 mg of potassium citrate and dissolve it in 1 mL of PEDOT:PSS stock solution. Stir thoroughly for 2 h, then dilute at a ratio of 1:9. Continue stirring for 2 h, then filter and refrigerate for later use.

[0091] Step 3) The ITO conductive glass is ultrasonically cleaned for 15 minutes each with ethanol, deionized water solution with cleaning agent, deionized water, acetone and ethanol, then dried with nitrogen and placed in an oven at 100℃ for more than 30 minutes for later use.

[0092] Step 4) The dried ITO conductive glass from step 3) is surface treated with an ultraviolet ozone cleaner for 15 minutes.

[0093] Step 5) In an air environment, take 45 μL of modified PEDOT:PSS solution and drop it onto the ITO conductive glass treated in the above steps. Spin coat it at 4000 rpm for 30 s, and then transfer it to a hot plate at 120℃ for annealing for 15 min.

[0094] Step 6) Take 60 μL of the perovskite precursor solution prepared in Step 1) and add it dropwise to the HTL obtained in Step 5). Spin coat at 1000 rpm for 5 s and 6000 rpm for 40 s. After spin coating, quickly transfer it to a hot plate at 150℃ for annealing for 7 min.

[0095] Step 7) Take 40 μL of pre-prepared 18 mg / ml PCBM chlorobenzene solution and drop it onto the perovskite film in Step 6). Spin coat at 1000 rpm for 60 s, then spin coat at 2000 rpm for 3 s to complete the preparation of the electron transport layer.

[0096] Step 8) Transfer the substrate obtained in Step 7) to a vacuum evaporation glove box, and use a high vacuum evaporation apparatus to deposit approximately 6 nm BCP and approximately 100 nm Ag electrodes on the electron transport layer to complete the fabrication of the perovskite solar cell device.

[0097] To illustrate the method for preparing vertically oriented Pb-Sn perovskite thin films at room temperature without anti-solvents provided by the present invention and its application in solar cells, the following description is provided in conjunction with the accompanying drawings.

[0098] Figure 2These are graphs showing the crystal growth of the precursor solution over time under an optical microscope under the conditions of Examples 1 and 2. from Figure 2 It is observed that in the absence of an atmosphere, the precursor solution rapidly forms small square grains with a high nucleation density. Subsequently, the nuclei grow rapidly in any direction along the framework extending in four directions, while new nuclei are formed simultaneously. Because the earliest appearing grains grow larger rapidly through diffusion absorption of solute, the growth of later-formed crystals is inhibited, ultimately resulting in uneven perovskite crystallization, low film coverage, and numerous defects. However, when a MAAc atmosphere is applied, the appearance of nuclei in the field of view under an optical microscope is delayed, and the nucleation density is significantly reduced. The precursor solution forms star-shaped nuclei more slowly, and over a longer period, the crystals only extend and grow along the four directions through diffusion absorption of solute at a suitable growth rate, ultimately leading to uniform perovskite crystallization and a film with high coverage, large grain size, and low defect rate.

[0099] Figure 3 Comparative diagrams of lead-tin perovskite thin film structures in Comparative Example 1 and Examples 3 and 4; from Figure 3 It can be seen that the HTL layer is first prepared by spin-coating PEDOT:PSS, and then NiO is spin-coated. x The PEDOT:PSS layer was modified to reduce defects at the PEDOT:PSS / perovskite interface, thus completing the HTL modification. Further spin-coating of a two-dimensional perovskite layer (F-PEA2PbI3SCN) modified the buried interface between NiOx and the perovskite layer, enabling the preparation of high-quality Pb-Sn perovskite films. The resulting lead-tin perovskite film structure is shown below. Figure 3 As shown.

[0100] Figure 4 These are morphological images of the upper and lower surface cross-sections of the lead-tin perovskite thin films prepared in Comparative Example 1 and Examples 3 and 4. from Figure 4 As can be seen, in Comparative Example 1, the perovskite grains are small and arbitrarily oriented, resulting in a film with numerous defects both on the surface and inside, and very obvious grain boundaries, which severely hinders carrier extraction and transport. In Example 3, the perovskite grains are smaller and exhibit a dense arrangement, especially at the lower interface, where the density and smoothness are significantly improved, indicating that NiO... xModifying the PEDOT:PSS layer improved the bottom interface contact of the film. Defects in the film were suppressed to some extent, but the grain orientation remained irregular, which was not conducive to carrier transport. In contrast, the perovskite in Example 4 exhibited uniform crystallization, larger and denser grains, and fewer film defects. More importantly, the crystals showed highly consistent out-of-plane orientation growth, with a highly ordered arrangement and a through-crystal mode. This structure effectively reduced grain boundary scattering and transport barriers, thereby significantly improving the migration and collection efficiency of carriers in the vertical direction.

[0101] Figure 5 The XRD patterns are of the lead-tin perovskite thin films prepared in Comparative Example 1 and Examples 1-4. from Figure 5 It can be seen that the application of the atmosphere effect and the modification of the buried interface both greatly improve the intensity of the characteristic diffraction peaks, indicating that the crystallinity of the film is further enhanced. To further verify the smoothness of the lead-tin perovskite film surface, AFM was used for characterization. The results show that, overall, the application of the atmosphere effect and the modification of the buried interface can make the film surface relatively smoother.

[0102] Figure 6 The images show the AFM and KPFM patterns of the lead-tin perovskite thin films prepared in Comparative Example 1 and Examples 3 and 4. from Figure 6 It can be seen that through NiO x After modification and application of the MAAc atmosphere, the surface smoothness of the film in Example 3 was significantly improved, and the surface roughness was reduced to 35.7 nm, consistent with its SEM morphology. However, after modification of the buried interface by the two-dimensional perovskite, the surface roughness of the film actually increased to 43.8 nm, with larger and denser grains. It is speculated that the modification of the buried interface by the two-dimensional perovskite can promote the improvement of the uniformity and crystallinity of the perovskite grown on its surface, inducing the perovskite to crystallize from bottom to top. The perovskite grown on the roughened surface after modification by the two-dimensional perovskite will also be rougher. The corresponding CPD change range is also reduced accordingly.

[0103] Figure 7 Here are the cross-sectional SEM images and structural schematic diagrams of the lead-tin perovskite device prepared in Example 4; from Figure 7 It can be seen that constructing a structure with ITO / PEDOT: PSS / NiO x A planar inverted perovskite solar cell device with a 2D PVK / perovskite / PCBM / BCP / Ag structure, as shown in the schematic diagram below. Figure 7 As shown in the image, the cross-sectional SEM image of the device reveals its clearly distinguishable planar multilayer stacked structure. The perovskite absorber layer consists of highly vertically oriented through-grains, a structure that helps reduce grain boundary defects and promotes efficient vertical carrier transport, thereby improving the performance of the optoelectronic device.

[0104] Figure 8 This refers to the lead-tin perovskite solar cells prepared in Comparative Examples 1 and 4. J - V Line graph; from Figure 8 It can be seen that thin-film fabricated devices prepared under different conditions... J - V Curves, such as Figure 8 As shown, compared to Comparative Example 1, NiO x Modification and the effect of two-dimensional perovskite on the buried interface can improve the device (Example 4). V OC and J SC Significant improvements were achieved, with the device's PCE increasing from 13.24% to 22.06%. Furthermore, the device's hysteresis (HI) decreased from 20.6% to 1.3%, indicating that the optimization strategy effectively improved the perovskite thin film crystal quality and interface contact, significantly suppressing carrier accumulation at the interface and reducing ion migration, non-radiative charge recombination, and energy loss within the thin film. This resulted in a significant reduction in the hysteresis of the optimized device.

[0105] Figure 9 The curves show the photoelectric conversion efficiency of the lead-tin perovskite solar cells prepared in Comparative Example 1 and Example 4 under nitrogen atmosphere as a function of time.

[0106] from Figure 9 It can be seen that the storage stability of the device in the N2 atmosphere is as follows: Figure 9 As shown, the device in Comparative Example 1 decayed to less than 50% of its initial PCE in just 400 h. In contrast, the unpackaged device in Example 4 exhibited excellent stability, maintaining over 95% of its initial PCE after 1600 h. This is attributed to the contribution of the optimization strategy to improving the device's FF, and also demonstrates its great potential for large-area fabrication of efficient and stable perovskite photovoltaic devices.

[0107] In summary, this invention obtains a lead-tin perovskite precursor solution by dissolving a lead-tin perovskite precursor, stannous fluoride, and formamidinium acetate in N,N-dimethylformamide solvent in a specific ratio and stirring until homogeneous. The lead-tin perovskite precursor solution is then spin-coated onto a hole transport layer substrate using a room-temperature, solvent-free method. Annealing then yields a lead-tin perovskite thin film with vertically oriented grains. This invention achieves in-situ formation of vertically oriented grains at room temperature without the need for anti-solvents, and the ionic liquid atmosphere method employed allows for significant control. The preparation process is simple, easy to operate, highly reproducible, and environmentally friendly. Lead-tin perovskite solar cell devices prepared using this method exhibit excellent photoelectric performance and superior device stability.

[0108] Although embodiments of the present invention have been shown and described above, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing vertically oriented Pb-Sn perovskite thin films at room temperature without anti-solvent, characterized in that, Includes the following steps: Methylamine iodide, formamidine iodide, cesium iodide, lead iodide, tin iodide, stannous fluoride, and formamidine acetate were dissolved in DMF and mixed evenly to obtain a lead-tin perovskite precursor solution. In an inert environment and in a methylamine acetic acid atmosphere, lead-tin perovskite precursor solution was spin-coated onto a substrate at room temperature. After annealing, a vertically oriented Pb-Sn perovskite thin film was obtained on the substrate.

2. The method for preparing vertically oriented Pb-Sn perovskite thin films at room temperature without anti-solvent according to claim 1, characterized in that, The molar ratio of methylamine iodide, formamidine amine iodide, cesium iodide, lead iodide, tin iodide, stannous fluoride, and formamidine acetate is approximately 0.3:0.65:0.05:0.5:0.5:(0.025~0.05):(0.4~0.7). The lead-tin perovskite precursor solution was obtained by stirring at 20-35°C until fully dissolved, and its molar concentration was 0.8-2.3 M. In the preparation of lead-tin perovskite precursor solution, after mixing evenly, Sn powder is added, dispersed evenly, allowed to stand, and then filtered using a 0.22 μm polytetrafluoroethylene filter membrane for later use.

3. The method for preparing vertically oriented Pb-Sn perovskite thin films at room temperature without anti-solvent according to claim 1, characterized in that, The annealing temperature is 100~180℃ for 6~12 min.

4. The method for preparing vertically oriented Pb-Sn perovskite thin films at room temperature without anti-solvent according to claim 1, characterized in that, In an inert environment and in a methylamine acetic acid atmosphere, a lead-tin perovskite precursor solution is spin-coated onto a substrate at room temperature, including: when spin-coating the lead-tin perovskite precursor solution onto the substrate in an inert environment, a cavity containing a methylamine acetic acid atmosphere is placed above the spin-coating. The substrate is a hole transport layer.

5. The method for preparing vertically oriented Pb-Sn perovskite thin films at room temperature without anti-solvent according to claim 4, characterized in that, The cavity containing the methylamine acetic acid atmosphere is formed by placing the methylamine acetic acid inside the cavity and preheating it to 70~90°C, so that the methylamine acetic acid vaporizes and evaporates throughout the cavity.

6. A vertically oriented Pb-Sn perovskite thin film prepared by the method according to any one of claims 1 to 5.

7. The application of the vertically oriented Pb-Sn perovskite thin film according to claim 6 in solar cells.

8. A solar cell, characterized in that, It includes an ITO conductive glass, a hole transport layer, a light absorption layer, an electron transport layer, an interface modification layer, and a metal back electrode, which are stacked in sequence. The light-absorbing layer is the vertically oriented Pb-Sn perovskite thin film as described in claim 7; The hole transport layer is prepared by spin coating PEDOT: PSS solution and / or NiO solution on ITO conductive glass in turn x solution; The electron transport layer is a PCBM; The interface modification layer is BCP; The metal back electrode is Ag; The PEDOT:PSS solution is a solution modified with potassium citrate.

9. A method for preparing a solar cell according to claim 8, characterized in that, Includes the following steps: Preparation of lead-tin perovskite precursor solution; The ITO conductive glass is cleaned, dried, and subjected to UV-ozone surface treatment, then a hole transport layer is spin-coated and annealed. In an inert environment and in a methylamine acetic acid atmosphere, lead-tin perovskite precursor solution was spin-coated onto the hole transport layer at room temperature, and annealed after film formation to obtain a vertically oriented Pb-Sn perovskite thin film. Electron transport layer fabricated on vertically oriented Pb-Sn perovskite thin film; An interface modification layer and a metal back electrode are vacuum-deposited on the electron transport layer.

10. The method for preparing a solar cell according to claim 9, characterized in that, When preparing vertically oriented Pb-Sn perovskite thin films on hole transport layers, a buried interface solution is first spin-coated onto the hole transport layers. When preparing an electron transport layer on a vertically oriented Pb-Sn perovskite film, an interface solution is first spin-coated onto the vertically oriented Pb-Sn perovskite film. The buried interface solution is prepared by uniformly dispersing F-PEAI, PbI2, Pb(SCN)2, NH4SCN and glycine ethyl hydrochloride in a mixed solution of DMSO and DMF, and preparing a solution with a concentration of 0.01~0.03 mol / L. The upper interface solution is prepared by dissolving EDAI2 and EDACl2 in a mixed solution of IPA and TL to obtain a concentration of 0.2~0.7 mg / ml.

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