A perovskite solar cell based on tin-based perovskite thin film and its fabrication method

Abstract

This invention discloses a perovskite solar cell based on a tin-based perovskite thin film and its fabrication method, belonging to the field of optoelectronic materials and devices. The invention involves spin-coating a hole transport layer onto conductive glass. A tin-based perovskite thin film is prepared by adding a two-dimensional perovskite single crystal to a tin-based perovskite precursor solution and using an anti-solvent method. After annealing, the addition of the two-dimensional perovskite single crystal helps to regulate the film phase distribution, reduce the crystallization rate, decrease non-radiative recombination, and promote interfacial carrier extraction and transport. An interface modification layer is then spin-coated; an electron transport layer material is vacuum-deposited onto the interface modification layer; and a hole blocking layer and a metal electrode are sequentially thermally deposited onto the electron transport layer material to obtain the perovskite solar cell. The tin-based perovskite solar cell prepared by this invention exhibits excellent photoelectric conversion efficiency and outstanding device stability, which is beneficial for promoting the development and application of tin-based perovskite solar cells.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic materials and devices technology, and specifically relates to a perovskite solar cell based on tin-based perovskite thin film and its preparation method. Background Technology

[0002] With the rapid development of science and technology, energy shortages and environmental pollution have received increasing attention. Photovoltaic technology, which generates electricity using solar energy without harming the environment, has garnered widespread interest as a green energy technology. Currently, silicon-based photovoltaic technology has achieved a power conversion efficiency of 27.09%, approaching the theoretical limit of single-junction solar cells. As a low-cost alternative to silicon-based photovoltaic technology, thin-film photovoltaic technology and emerging photovoltaic technologies are being extensively explored. These technologies are based on various light-absorbing materials, such as chalcogenide semiconductors, organic semiconductors, quantum dots, dyes, and halide perovskites. Although all these mainstream photovoltaic technologies still lag behind the market-dominant silicon-based photovoltaics in terms of efficiency and stability, they can produce lower carbon emissions and faster energy payback periods, bringing a bright future to various photovoltaic technologies.

[0003] Over the past decade, the superior photovoltaic performance of metal halide perovskite solar cells has highlighted their potential, with power conversion efficiencies rising from an initial 3.8% to over 26% today. However, the long-term operational stability and toxicity of lead-based halide perovskites have hindered their further widespread application. Tin-based perovskite materials, on the other hand, theoretically possess good or even superior photoelectric performance compared to lead-based perovskites due to their lower toxicity, near-theoretical band gap, smaller exciton binding energy, and higher carrier mobility. However, the easy oxidation of divalent tin to tetravalent tin in tin-based perovskites and the difficulty in controlling their crystallization process lead to high defect density and severe p-type doping, ultimately impairing device efficiency and stability.

[0004] Therefore, by introducing various large organic cations, such as phenylethylamine and ethylenediamine, into the tin-based perovskite system, p-type self-doping can be reduced, thus improving the stability of tin-based perovskite solar cells. However, the introduction of large organic cations can lead to the formation of a low n-value phase, which inhibits carrier transport, intensifies nonradiative recombination, and degrades the performance of tin-based perovskite solar cells. Summary of the Invention

[0005] To address the technical problems of poor carrier transport and increased nonradiative recombination in perovskite films caused by the formation of undesirable low-n-value phases after the addition of large organic cations to tin-based perovskites, this invention aims to propose a method for introducing two-dimensional perovskite single crystals to adjust the distribution of two-dimensional and three-dimensional phases in tin-based perovskites, optimize the crystallization process, and prepare high-quality tin-based perovskite films and efficient and stable tin-based perovskite solar cells. The prepared tin-based perovskite solar cells have the characteristics of good phase distribution, slow crystallization rate, low nonradiative recombination, and fast interfacial carrier extraction and transport.

[0006] The present invention is achieved through the following technical solution.

[0007] One aspect of the present invention provides a method for fabricating a perovskite solar cell based on a tin-based perovskite thin film, comprising the following steps:

[0008] (1) The etched ITO conductive glass is cleaned and baked to obtain a clean ITO substrate;

[0009] (2) Dissolve the interface modification layer material in a mixed solvent of isopropanol and toluene to prepare an interface modification layer precursor solution;

[0010] (3) A tin-based perovskite precursor solution was prepared by dissolving two-dimensional perovskite single crystals, formamidinium iodide, stannous iodide, germanium iodide, stannous fluoride, and phenylethylammonium bromide in mixed solvent A at a molar ratio of (0.01-0.05):(0.90-1.00):(0.90-1.00):(0.05-0.10).

[0011] (4) A hole transport layer material is spin-coated onto a cleaned and treated ITO transparent conductive glass to deposit a hole transport layer.

[0012] (5) The tin-based perovskite precursor liquid was spin-coated onto ITO transparent conductive glass with hole transport layer material deposited by the anti-solvent method, and then annealed to obtain a tin-based perovskite thin film.

[0013] (6) Spin-coating an interface modification layer material onto a tin-based perovskite thin film to deposit an interface modification layer;

[0014] (7) Vacuum thermal evaporation of electron transport material on interface modification layer;

[0015] (8) A hole blocking layer and a metal electrode are thermally deposited on the electron transport material to complete the fabrication of a perovskite solar cell.

[0016] Preferably, the interface modification layer material is one or more of ethylenediamine hydroiodate, phenylethyl ammonium chloride, or ethylenediamine hydrochloride, with a concentration of 0.5–2 mg / mL.

[0017] Preferably, the two-dimensional perovskite single crystal is prepared according to the following steps:

[0018] Two-dimensional single crystal precursor molecules were mixed with hydroiodic acid at a molar ratio of 1:(1-3). 0.1-0.3 mL of diethyl ether was added to every 40 μL of the mixture to trigger crystallization. After washing, filtering, and drying, single crystal precursor powder was obtained. This powder was then mixed with stannous chloride (SnCl2) at a molar ratio of 1:(1-2) and added to mixed solvent B. The mixture was heated to 90-100 °C with continuous stirring until the solution turned bright yellow. After cooling to room temperature, two-dimensional perovskite single crystals were obtained.

[0019] Preferably, the two-dimensional single-crystal precursor molecule is one or more of 3-aminomethylpyridine or 3-aminomethylpiperidine;

[0020] Mixed solvent A is a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1;

[0021] The mixed solvent B is an aqueous solution of hydroiodic acid and an aqueous solution of hypophosphoric acid in a weight ratio of (55%–60%):(45%–55%).

[0022] Preferably, the hole transport layer material is poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid PEDOT:PSS;

[0023] Spin coat at 4000–6000 rpm for 40–60 seconds, then anneal at 120–140°C for 20–30 minutes.

[0024] Preferably, in step (5), the tin-based perovskite film is deposited using an anti-solvent method, including:

[0025] A perovskite precursor solution with a concentration of 0.8–1.5 mol / L was dropped onto an ITO transparent conductive glass substrate with a hole transport layer material deposited on it. The substrate was then spin-coated at 4000–8000 rpm for 40–80 s in a nitrogen atmosphere. An antisolvent was added dropwise during the last 18–25 s, and the substrate was annealed at 100–120 °C for 10–20 min to obtain a tin-based perovskite film. The antisolvent was anhydrous chlorobenzene, toluene, ethyl acetate, or diethyl ether.

[0026] Preferably, in step (6), the interface modification layer material is spin-coated onto the tin-based perovskite film at a rotation speed of 4000-6000 rpm in a nitrogen atmosphere for 20-40 seconds, and then annealed at 100-120℃ for 5-10 minutes.

[0027] Preferably, the electron transport layer is C. 60 The thickness is 20–40 nm;

[0028] The hole-blocking layer is made of copper bath and has a thickness of 5-10 nm.

[0029] The metal electrode Ag is vapor-deposited with a thickness of 80–150 nm.

[0030] In another aspect, the present invention provides a perovskite solar cell based on a tin-based perovskite thin film prepared by the method.

[0031] The present invention, by adopting the above technical solution, has the following beneficial effects:

[0032] (1) Optimized crystallization process: In this invention, an appropriate proportion of two-dimensional perovskite single crystals are added to the tin-based perovskite precursor solution. Through the strong electrostatic and hydrogen bonding interactions between the single crystals and the tin-based perovskite framework, the distribution of the two-dimensional and three-dimensional phases in the tin-based perovskite film is effectively regulated, while the Sn content in the tin-based perovskite film is suppressed. 2+ The oxidation and self-p-type doping reduce the defect density and non-radiative losses in the film, slow down the crystallization rate, and optimize the crystallization process.

[0033] (2) Improved film quality: By utilizing optimized spin-coating methods and heat treatment processes, high-quality two-dimensional / three-dimensional mixed-phase tin-based perovskite films with high flatness, few surface defects, and fast carrier extraction and transport were obtained.

[0034] (3) Enhanced water and oxygen barrier capability: The introduction of two-dimensional perovskite single crystals enables the prepared tin-based perovskite thin film to have excellent water and oxygen barrier capability, which can effectively prevent the intrusion of moisture and oxygen in the environment, thereby significantly improving the long-term stability of perovskite solar cells and extending the device life.

[0035] (4) Improved device performance: The efficiency and stability of the tin-based perovskite solar cells prepared by this invention are significantly improved. Compared with tin-based perovskite solar cells prepared without using two-dimensional perovskite single crystals, the highest conversion efficiency increases from 10.91% to 13.28%, an increase of approximately 21.72%. After being placed in a nitrogen atmosphere for 3000 hours without encapsulation, the photoelectric conversion efficiency of the cell still remains at approximately 96% of the initial value. Attached Figure Description

[0036] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, do not constitute an undue limitation of the invention. In the drawings:

[0037] Figure 1(a) is a SEM image of the tin-based perovskite film prepared in Comparative Example 1; Figure 1(b) is a SEM image of the tin-based perovskite film prepared in Example 1.

[0038] Figure 2XRD patterns of the tin-based perovskite films prepared in Comparative Example 1(a) and Example 1(b);

[0039] Figure 3 Fluorescence lifetime diagrams of the tin-based perovskite films prepared in Comparative Example 1(a) and Example 1(b);

[0040] Figure 4(a) shows the transient absorption curve of the tin-based perovskite film prepared in Comparative Example 1; Figure 4(b) shows the transient absorption curve of the tin-based perovskite film prepared in Example 1.

[0041] Figure 5 This is a structural diagram of the tin-based perovskite solar cell device prepared according to the present invention;

[0042] Figure 6 JV curves of the low-dimensional tin-based perovskite solar cells prepared in Comparative Example 1(a) and Example 1(b);

[0043] Figure 7 The graph shows the change in photoelectric conversion efficiency over time for the tin-based perovskite solar cells prepared in Comparative Example 1(a) and Example 1(b). Detailed Implementation

[0044] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0045] The method for fabricating a perovskite solar cell based on a tin-based perovskite thin film provided in this invention includes the following specific steps:

[0046] Step 1: The etched ITO conductive glass is ultrasonically treated in ethanol, ultrapure water with cleaning agent, ultrapure water, and ethanol for 20-30 minutes each, and then baked in an oven to obtain a clean ITO substrate.

[0047] Step 2: Dissolve the interface modification layer material, ethylenediamine hydroiodide, phenylethyl ammonium chloride, or ethylenediamine hydrochloride, in a mixed solvent of isopropanol and toluene to prepare an interface modification layer precursor solution of 0.5–2 mg / mL.

[0048] Step 3: Dissolve two-dimensional perovskite single crystals, formamidinium iodide, stannous iodide, germanium iodide, stannous fluoride, and phenylethylamine bromide in a mixed solvent A of N,N-dimethylformamide and dimethylformamide at a volume ratio of (0.01-0.05):(0.90-1.00):(0.90-1.00):(0.05-0.10):(0.10-0.50):(0.05-0.10). Stir at room temperature for 3-5 hours to prepare a solution with a concentration of 0.8-1.5 mol / L. -1The perovskite precursor solution.

[0049] Two-dimensional perovskite single crystals are prepared according to the following steps:

[0050] Two-dimensional single-crystal precursor molecules 3-aminomethylpyridine or 3-aminomethylpiperidine were reacted with hydroiodic acid in a flask at a molar ratio of 1:(1-3). 0.1–0.3 mL of diethyl ether was added per 40 μL of the mixture, and the mixture was then placed in a refrigerator to trigger crystallization. After washing with diethyl ether 3–5 times, filtering, and drying under vacuum at 60–70 °C for 12–15 h, a single-crystal precursor powder was obtained. This powder was then mixed with stannous chloride (SnCl2) at a molar ratio of 1:(1-2) and added to a mixed solvent B (a hydroiodic acid aqueous solution and a hypophosphite aqueous solution with a weight ratio of (55%–60%):(45%–55%). The mixture was heated to 90–100 °C with continuous stirring until the solution turned bright yellow. The solution was then cooled to room temperature at a rate of 8–12 °C / h to obtain two-dimensional perovskite single crystals.

[0051] Step 4: Treat the cleaned ITO substrate with ultraviolet ozone for 20 minutes. Spin-coat the cleaned and treated ITO transparent conductive glass with hole transport material poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid PEDOT:PSS to deposit the hole transport layer.

[0052] Hole transport material PEDOT:PSS was dropped onto the treated ITO conductive glass using a pipette and spin-coated at 4000-6000 rpm for 40-60 seconds. The ITO coated with PEDOT:PSS was then annealed at 120-140°C for 20-30 minutes.

[0053] Step 5: Drop a perovskite precursor solution with a concentration of 0.8–1.5 mol / L onto an ITO substrate with a hole transport layer material deposited on it. Spin coat the substrate at 4000–8000 rpm for 40–80 s in a nitrogen atmosphere. Add an antisolvent dropwise in the last 18–25 s. Then anneal at 100–120 °C for 10–20 min to obtain a black tin-based perovskite film.

[0054] The antisolvent is anhydrous chlorobenzene, toluene, ethyl acetate, or diethyl ether.

[0055] Step 6: Spin-coat an interface modification layer material (ethylenediamine hydroiodide, phenylethyl ammonium chloride, or ethylenediamine hydrochloride) with a concentration of 0.5–2 mg / mL at a speed of 4000–6000 rpm for 20–40 s in a nitrogen atmosphere, and anneal at 100–120 °C for 5–10 min.

[0056] Step 7: Vacuum thermal evaporation deposition technology is used to deposit 20-40 nm C on the tin-based perovskite thin film of Step 6. 60Thus, the electron transport layer is obtained.

[0057] Step 8: Using vacuum thermal evaporation technology, a hole blocking layer of copper bath with a thickness of 5-10 nm and a metal electrode Ag with a thickness of 80-150 nm are deposited on the electron transport layer in step 7 to obtain a tin-based perovskite solar cell.

[0058] The present invention will be further illustrated below through different embodiments.

[0059] Example 1

[0060] Step 1) The etched ITO conductive glass is ultrasonically treated in ethanol, ultrapure water with cleaning agent, ultrapure water and ethanol for 20-30 minutes each, and then baked in an oven to obtain a clean ITO substrate.

[0061] Step 2) Dissolve the interface modification layer material ethylenediamine hydroiodate in a mixed solvent of isopropanol and toluene to prepare an interface modification layer precursor solution of 1 mg / mL.

[0062] Step 3) Dissolve two-dimensional perovskite single crystals, formamidinium iodide, stannous iodide, germanium iodide, stannous fluoride, and phenylethylamine bromide in a mixed solvent A of N,N-dimethylformamide and dimethylformamide in a volume ratio of 4:1 according to a molar ratio of 0.01:1.00:1.00:0.10:0.10:0.06. Stir at room temperature for 4 hours to prepare a solution with a concentration of 0.9 mol / L. -1 The perovskite precursor solution.

[0063] Two-dimensional perovskite single crystals are prepared according to the following steps:

[0064] The two-dimensional single-crystal precursor molecule 3-aminomethylpyridine was reacted with hydroiodic acid in a flask at a molar ratio of 1:2. 0.2 mL of diethyl ether was added for every 40 μL of the mixture, and the mixture was then placed in a refrigerator to trigger crystallization. After washing three times with diethyl ether, filtering, and drying under vacuum at 60 °C for 15 h, a single-crystal precursor powder was obtained. This powder was then mixed with stannous chloride (SnCl2) at a molar ratio of 1:1 and added to a mixed solvent B (a 55%:45% hydroiodic acid aqueous solution and a hypophosphite aqueous solution by weight). The mixture was heated to 95 °C with continuous stirring until the solution turned bright yellow. The solution was then cooled to room temperature at a rate of 10 °C / h to obtain a two-dimensional perovskite single crystal. Step 4) The ITO substrate cleaned in Step 1 was treated with ultraviolet ozone for 20 minutes. A hole transport material, poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid PEDOT:PSS, was spin-coated onto the cleaned and treated ITO transparent conductive glass to deposit a hole transport layer.

[0065] Hole transport material PEDOT:PSS was dropped onto the prepared ITO conductive glass using a pipette, and spin-coated at 4000 rpm for 50 seconds. The ITO coated with PEDOT:PSS was then annealed at 140°C for 20 minutes.

[0066] Step 5) Drop a 0.9 mol / L perovskite precursor solution onto an ITO substrate with a hole transport layer material deposited on it. Spin coat the substrate at 8000 rpm for 60 s in a nitrogen atmosphere. Add the antisolvent chlorobenzene in the last 18-25 s. Then anneal at 100 °C for 10 min to obtain a black tin-based perovskite film.

[0067] Step 6) Spin-coat an interface modification layer material of 1 mg / mL ethylenediamine hydroiodide at 5000 rpm for 30 s in a nitrogen atmosphere, and anneal at 100℃ for 5 min.

[0068] Step 7) A 20 nm C film is deposited on the tin-based perovskite film from Step 6 using vacuum thermal evaporation technology. 60 Thus, the electron transport layer is obtained.

[0069] Step 8) Using vacuum thermal evaporation technology, a hole blocking layer of copper bath with a thickness of 10 nm and a metal electrode Ag with a thickness of 120 nm are deposited on the electron transport layer in step 7 to obtain a tin-based perovskite solar cell.

[0070] Under standard test conditions (AM1.5G illumination), the solar cell device prepared in this embodiment exhibits a photoelectric conversion efficiency of 13.28%, an open-circuit voltage of 0.78V, and a short-circuit current of 23.31mA / cm². 2 The fill factor is 73.08%.

[0071] Example 2

[0072] Step 1) The etched ITO conductive glass is ultrasonically treated in ethanol, ultrapure water with cleaning agent, ultrapure water and ethanol for 30 minutes each, and then baked in an oven to obtain a clean ITO substrate.

[0073] Step 2) Dissolve the interface modification layer material ethylenediamine hydroiodate in a mixed solvent of isopropanol and toluene to prepare an interface modification layer precursor solution of 0.5 mg / mL.

[0074] Step 3) Dissolve two-dimensional perovskite single crystals, formamidinium iodide, stannous iodide, germanium iodide, stannous fluoride, and phenylethylamine bromide in a mixed solvent A of N,N-dimethylformamide and dimethylformamide in a volume ratio of 4:1 according to a molar ratio of 0.02:0.90:0.90:0.08:0.30:0.05. Stir at room temperature for 5 hours to prepare a solution with a concentration of 1.2 mol / L. -1 The perovskite precursor solution.

[0075] Two-dimensional perovskite single crystals were prepared according to the following steps: 3-aminomethylpyridine, a precursor molecule for two-dimensional single crystals, was reacted with hydroiodic acid in a flask at a molar ratio of 1:3. 0.2 mL of diethyl ether was added per 40 μL of the mixture, and the mixture was then placed in a refrigerator to trigger crystallization. After washing four times with diethyl ether, filtering, and drying under vacuum at 70 °C for 12 h, a single crystal precursor powder was obtained. This powder was then mixed with stannous chloride (SnCl2) at a molar ratio of 1:1.5 and added to a mixed solvent B (a 60%:40% aqueous solution of hydroiodic acid and a 60%:40% aqueous solution of hypophosphite by weight). The mixture was heated to 90 °C with continuous stirring until the solution turned bright yellow. The solution was then cooled to room temperature at a rate of 8 °C / h to obtain the two-dimensional perovskite single crystal.

[0076] Step 4) Treat the cleaned ITO substrate with ultraviolet ozone for 20 minutes, and spin-coat the hole transport material poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid PEDOT:PSS onto the cleaned and treated ITO transparent conductive glass to deposit the hole transport layer.

[0077] Hole transport material PEDOT:PSS was dropped onto the prepared ITO conductive glass using a pipette, and spin-coated at 5000 rpm for 50 seconds. The ITO coated with PEDOT:PSS was then annealed at 130°C for 25 minutes.

[0078] Step 5) Drop a 1.5 mol / L perovskite precursor solution onto an ITO substrate with a hole transport layer material deposited on it. Spin coat the substrate at 6000 rpm for 40 seconds in a nitrogen atmosphere. Add the antisolvent toluene in the last 18 to 25 seconds, and then anneal at 120°C for 10 minutes to obtain a black tin-based perovskite film.

[0079] Step 6) Spin-coat the interface modification layer material ethylenediamine hydrochloride with a concentration of mg / mL at 4000 rpm for 40 s in a nitrogen atmosphere, and anneal at 100℃ for 10 min.

[0080] Step 7) A 30 nm C film is deposited on the tin-based perovskite film from Step 6 using vacuum thermal evaporation technology. 60 Thus, the electron transport layer is obtained.

[0081] Step 8) Using vacuum thermal evaporation technology, a hole blocking layer of copper bath with a thickness of 5 nm and a metal electrode Ag with a thickness of 150 nm are deposited on the electron transport layer in step 7 to obtain a tin-based perovskite solar cell.

[0082] Under standard test conditions (AM1.5G illumination), the solar cell device prepared in this embodiment exhibits a photoelectric conversion efficiency of 12.94%, an open-circuit voltage of 0.78V, and a short-circuit current of 22.93mA / cm². 2 The fill factor is 72.35%.

[0083] Example 3

[0084] Step 1) The etched ITO conductive glass is ultrasonically treated in ethanol, ultrapure water with cleaning agent, ultrapure water and ethanol for 25 minutes each, and then baked in an oven to obtain a clean ITO substrate.

[0085] Step 2) Dissolve the interface modification layer material ethylenediamine hydroiodate in a mixed solvent of isopropanol and toluene to prepare an interface modification layer precursor solution of 1.5 mg / mL.

[0086] Step 3) Dissolve two-dimensional perovskite single crystals, formamidinium iodide, stannous iodide, germanium iodide, stannous fluoride, and phenylethylamine bromide in a mixed solvent A of N,N-dimethylformamide and dimethylformamide in a volume ratio of 4:1 according to a molar ratio of 0.04:1.00:1.00:0.05:0.10:0.07. Stir at room temperature for 3 hours to prepare a solution with a concentration of 1.5 mol / L. -1 The perovskite precursor solution.

[0087] Two-dimensional perovskite single crystals are prepared according to the following steps:

[0088] The two-dimensional single-crystal precursor molecule 3-aminomethylpiperidine was reacted with hydroiodic acid in a flask at a molar ratio of 1:1. 0.3 mL of diethyl ether was added for every 40 μL of the mixture, and the mixture was then placed in a refrigerator to trigger crystallization. After washing five times with diethyl ether, filtering, and drying under vacuum at 65 °C for 14 h, the single-crystal precursor powder was obtained. This powder was then mixed with stannous chloride SnCl2 at a molar ratio of 1:2 and added to mixed solvent B (57%:43% hydroiodic acid aqueous solution and hypophosphite aqueous solution by weight). The mixture was heated to 100 °C with continuous stirring until the solution turned bright yellow. The solution was then cooled to room temperature at a rate of 9 °C / h to obtain two-dimensional perovskite single crystals.

[0089] Step 4) Treat the cleaned ITO substrate with ultraviolet ozone for 20 minutes, and spin-coat the hole transport material poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid PEDOT:PSS onto the cleaned and treated ITO transparent conductive glass to deposit the hole transport layer.

[0090] Hole transport material PEDOT:PSS was dropped onto the prepared ITO conductive glass using a pipette and spin-coated at 4000 rpm for 60 seconds. The ITO coated with PEDOT:PSS was then annealed at 140°C for 20 minutes.

[0091] Step 5) Drop the 0.8 mol / L perovskite precursor solution onto the ITO substrate on which the hole transport layer material has been deposited. Spin-coat at 4000 rpm for 80 s in a nitrogen atmosphere. Add the antisolvent ethyl acetate dropwise in the last 18-25 s. Then anneal at 110 °C for 15 min to obtain a black tin-based perovskite film.

[0092] Step 6) Spin-coat the interface modification layer material phenylethyl ammonium chloride with a concentration of 1.5 mg / mL at 4500 rpm for 30 s in a nitrogen atmosphere, and anneal at 120℃ for 5 min.

[0093] Step 7) A 40 nm C film is deposited on the tin-based perovskite film from Step 6 using vacuum thermal evaporation technology. 60 Thus, the electron transport layer is obtained.

[0094] Step 8) Using vacuum thermal evaporation technology, a hole blocking layer of copper bath with a thickness of 8 nm and a metal electrode Ag with a thickness of 100 nm are deposited on the electron transport layer in step 7 to obtain a tin-based perovskite solar cell.

[0095] Under standard test conditions (AM1.5G illumination), the solar cell device prepared in this embodiment exhibits a photoelectric conversion efficiency of 12.72%, an open-circuit voltage of 0.76V, and a short-circuit current of 23.06mA / cm². 2 The fill factor is 72.59%.

[0096] Example 4

[0097] Step 1) The etched ITO conductive glass is ultrasonically treated in ethanol, ultrapure water with cleaning agent, ultrapure water and ethanol for 30 minutes each, and then baked in an oven to obtain a clean ITO substrate.

[0098] Step 2) Dissolve the interface modification layer material ethylenediamine hydroiodate in a mixed solvent of isopropanol and toluene to prepare a 2 mg / mL interface modification layer precursor solution.

[0099] Step 3) Dissolve two-dimensional perovskite single crystals, formamidinium iodide, stannous iodide, germanium iodide, stannous fluoride, and phenylethylamine bromide in a mixed solvent A of N,N-dimethylformamide and dimethylformamide in a volume ratio of 4:1 according to a molar ratio of 0.05:0.90:0.90:0.09:0.50:0.10. Stir at room temperature for 4 hours to prepare a solution with a concentration of 0.8 mol / L. -1 The perovskite precursor solution.

[0100] Two-dimensional perovskite single crystals are prepared according to the following steps:

[0101] The two-dimensional single-crystal precursor molecule 3-aminomethylpiperidine was reacted with hydroiodic acid in a flask at a molar ratio of 1:1.5. 0.2 mL of diethyl ether was added for every 40 μL of the mixture, and the mixture was then placed in a refrigerator to trigger crystallization. After washing with diethyl ether four times, filtering, and drying under vacuum at 70 °C for 13 h, the single-crystal precursor powder was obtained. The powder was then mixed with stannous chloride SnCl2 at a molar ratio of 1:1 and added to mixed solvent B (58%:42% hydroiodic acid aqueous solution and hypophosphite aqueous solution by weight). The mixture was heated to 90 °C with continuous stirring until the solution turned bright yellow. The solution was then cooled to room temperature at a rate of 12 °C / h to obtain two-dimensional perovskite single crystals.

[0102] Step 4) Treat the cleaned ITO substrate with ultraviolet ozone for 20 minutes, and spin-coat the hole transport material poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid PEDOT:PSS onto the cleaned and treated ITO transparent conductive glass to deposit the hole transport layer.

[0103] Hole transport material PEDOT:PSS was dropped onto the prepared ITO conductive glass using a pipette and spin-coated at 4500 rpm for 55 seconds. The ITO coated with PEDOT:PSS was then annealed at 140°C for 25 minutes.

[0104] Step 5) Drop a 1.2 mol / L perovskite precursor solution onto an ITO substrate with a hole transport layer material deposited on it. Spin coat the substrate at 5500 rpm for 45 s in a nitrogen atmosphere. Add the antisolvent diethyl ether in the last 18-25 s. Then anneal at 120 °C for 15 min to obtain a black tin-based perovskite film.

[0105] Step 6) Spin-coat the interface modification layer material ethylenediamine hydroiodide with a concentration of 0.5 mg / mL at 6000 rpm for 20 s in a nitrogen atmosphere, and anneal at 100 °C for 8 min.

[0106] Step 7) A 25nm C film is deposited on the tin-based perovskite film from Step 6 using vacuum thermal evaporation technology. 60 Thus, the electron transport layer is obtained.

[0107] Step 8) Using vacuum thermal evaporation technology, a hole blocking layer of copper bath with a thickness of 9 nm and a metal electrode Ag with a thickness of 80 nm are deposited on the electron transport layer in step 7 to obtain a tin-based perovskite solar cell.

[0108] Under standard test conditions (AM1.5G illumination), the solar cell device prepared in this embodiment exhibits a photoelectric conversion efficiency of 12.09%, an open-circuit voltage of 0.76V, and a short-circuit current of 22.21mA / cm². 2 The fill factor is 71.68%.

[0109] The following comparison of the inverted planar tin-based perovskite solar cells prepared in Comparative Example 1 and Example 1 is provided to give a full understanding of the present invention.

[0110] Comparative Example 1

[0111] Step 1) The etched ITO conductive glass is ultrasonically treated in ethanol, ultrapure water with cleaning agent, ultrapure water and ethanol for 20 minutes each, and then baked in an oven to obtain a clean ITO substrate.

[0112] Step 2) Dissolve the interface modification layer material ethylenediamine hydroiodate in a mixed solvent of isopropanol and toluene to prepare an interface modification layer precursor solution of 1 mg / mL.

[0113] Step 3) Dissolve formamidinium iodide, stannous iodide, germanium iodide, stannous fluoride, and phenylethyl ammonium bromide in a mixed solvent A of N,N-dimethylformamide and dimethylformamide in a volume ratio of 4:1 according to a molar ratio of 1.00:1.00:0.10:0.10:0.06. Stir at room temperature for 4 hours to prepare a solution with a concentration of 0.9 mol / L. -1 The perovskite precursor solution.

[0114] Step 4) Treat the cleaned ITO substrate with ultraviolet ozone for 20 minutes, and spin-coat the hole transport material poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid PEDOT:PSS onto the cleaned and treated ITO transparent conductive glass to deposit the hole transport layer.

[0115] Hole transport material PEDOT:PSS was dropped onto the prepared ITO conductive glass using a pipette, and spin-coated at 4000 rpm for 50 seconds. The ITO coated with PEDOT:PSS was then annealed at 140°C for 20 minutes.

[0116] Step 5) Drop a 0.9 mol / L perovskite precursor solution onto an ITO substrate with a hole transport layer material deposited on it. Spin coat the substrate at 8000 rpm for 60 s in a nitrogen atmosphere. Add the antisolvent chlorobenzene in the last 18-25 s. Then anneal at 100 °C for 10 min to obtain a black tin-based perovskite film.

[0117] Step 6) Spin-coat an interface modification layer material of 1 mg / mL ethylenediamine hydroiodide at 5000 rpm for 30 s in a nitrogen atmosphere, and anneal at 100℃ for 5 min.

[0118] Step 7) A 20 nm C film is deposited on the tin-based perovskite film from Step 6 using vacuum thermal evaporation technology. 60 Thus, the electron transport layer is obtained.

[0119] Step 8) Using vacuum thermal evaporation technology, a hole blocking layer of copper bath with a thickness of 10 nm and a metal electrode Ag with a thickness of 120 nm are deposited on the electron transport layer in step 7 to obtain a tin-based perovskite solar cell.

[0120] Figure 1(a) and (b) are SEM images of the tin-based perovskite films prepared in Comparative Example 1 and Example 1. After adding two-dimensional perovskite single crystals to the precursor, the average grain size of the film increased from ~0.40 μm to ~0.45 μm, indicating that the crystallization rate slowed down and the quality of the obtained film increased.

[0121] Figure 2 In Figures (a) and (b), the XRD patterns of the tin-based perovskite films prepared in Comparative Example 1 and Example 1, respectively, further show that the diffraction peak intensity increases after adding two-dimensional perovskite single crystals to the precursor, indicating that the crystallinity of the film increases and the quality of the obtained film is improved.

[0122] Figure 3 In Figures (a) and (b), the fluorescence lifetimes of the tin-based perovskite films prepared in Comparative Example 1 and Example 1, respectively, show that the absorbing layer of the tin-based perovskite film prepared in Example 1 increases the carrier lifetime from 3.94 ns to 15.81 ns, indicating that the defect state density in the film is reduced.

[0123] Figures 4(a) and (b) are transient absorption diagrams of the tin-based perovskite films prepared in Comparative Example 1 and Example 1. It can be seen that compared with Comparative Example 1, the content of the two-dimensional phase in the tin-based perovskite film prepared in Example 1 is reduced and the content of the three-dimensional phase is increased. This indicates that the addition of the two-dimensional perovskite single crystal 3AMPYSnI4 successfully regulates the phase distribution in the tin-based perovskite film, which is beneficial to the improvement of the photovoltaic performance of the device.

[0124] Figure 5 This is a structural diagram of the tin-based perovskite solar cell device prepared in Example 1. From bottom to top, it consists of an ITO conductive substrate, a hole transport layer, a tin-based perovskite thin film light-absorbing layer, an electron transport layer, a hole blocking layer, and a metal electrode layer.

[0125] Figure 6 In Figures (a) and (b), the JV curves of the low-dimensional tin-based perovskite solar cells prepared in Comparative Example 1 and Example 1, respectively, are shown. The photovoltaic performance of the perovskite solar cell prepared in Example 1 is significantly better than that of Comparative Example 1.

[0126] Figure 7The graph shows the change in photoelectric conversion efficiency over time for the tin-based perovskite solar cells prepared in Comparative Example 1 and Example 1. It can be seen that the stability of the device with the addition of two-dimensional perovskite single crystal is significantly improved, and it still maintains about 96% of the initial efficiency after being stored in a nitrogen atmosphere for more than 3000 hours.

[0127] As can be seen from the above embodiments, the solar cell device prepared by the present invention has a photoelectric conversion efficiency of up to 13.28%, an open-circuit voltage as high as 0.78V, and a short-circuit current of up to 23.31mA / cm². 2 The maximum fill factor is 73.08%. It has a good crystallization process, excellent carrier extraction and transport capabilities, and a smooth and dense surface with good water and oxygen barrier capabilities, which greatly improves the photoelectric conversion efficiency and device stability of perovskite solar cells.

[0128] This method can significantly optimize the distribution of two-dimensional and three-dimensional phases in tin-based perovskite thin films, slow down the film crystallization rate, improve carrier extraction and transport rates, reduce defect state density, and enhance the long-term stability of the device. This invention prepares tin-based perovskite thin films by adding two-dimensional perovskite single crystals to a tin-based perovskite precursor solution and using an anti-solvent method. The addition of these two-dimensional perovskite single crystal molecules helps to regulate the film phase distribution, reduce the crystallization rate, decrease non-radiative recombination, and promote interfacial carrier extraction and transport. The tin-based perovskite solar cells prepared based on this invention exhibit excellent photoelectric conversion efficiency and outstanding water and oxygen barrier capabilities, significantly improving the environmental stability of the device.

[0129] This invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and modifications to some of the technical features without creative effort, and all such substitutions and modifications are within the protection scope of this invention.

Claims

1. A method for fabricating a perovskite solar cell based on a tin-based perovskite thin film, characterized in that, Includes the following steps: (1) Clean and bake the etched ITO conductive glass to obtain a clean ITO substrate; (2) Dissolve the interface modification layer material in a mixed solvent of isopropanol and toluene to prepare an interface modification layer precursor solution; (3) A tin-based perovskite precursor solution is prepared by dissolving two-dimensional perovskite single crystals, formamidinium iodide, stannous iodide, germanium iodide, stannous fluoride, and phenylethylammonium bromide in mixed solvent A at a molar ratio of (0.01-0.05):(0.90-1.00):(0.90-1.00):(0.05-0.10). The two-dimensional perovskite single crystal is prepared according to the following steps: Two-dimensional single-crystal precursor molecules were mixed with hydroiodic acid at a molar ratio of 1:(1-3), and 0.1~0.3 mL of diethyl ether was added for every 40 μL of the mixture to trigger crystallization. After washing, filtering and drying, a single crystal precursor powder is obtained. Then, it is mixed with stannous chloride SnCl2 at a molar ratio of 1:(1-2) and added to mixed solvent B. The mixture is heated to 90~100℃ with continuous stirring until the solution turns bright yellow. After cooling to room temperature, a two-dimensional perovskite single crystal is obtained. The two-dimensional single-crystal precursor molecule is one or more of 3-aminomethylpyridine or 3-aminomethylpiperidine; Mixed solvent A is a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1; The mixed solvent B is an aqueous solution of hydroiodic acid and an aqueous solution of hypophosphoric acid in a weight ratio of (55%~60%):(45%~55%). (4) A hole transport layer material is spin-coated onto the cleaned and treated ITO transparent conductive glass to deposit a hole transport layer; (5) The tin-based perovskite precursor liquid was spin-coated onto ITO transparent conductive glass with hole transport layer material deposited by the anti-solvent method, and the tin-based perovskite thin film was obtained by annealing. (6) Spin-coating an interface modification layer material onto a tin-based perovskite thin film to deposit an interface modification layer; (7) Vacuum thermal evaporation of electron transport material on the interface modification layer; (8) A hole blocking layer and a metal electrode are thermally deposited on the electron transport material to complete the fabrication of a perovskite solar cell.

2. The method for fabricating a perovskite solar cell based on a tin-based perovskite thin film according to claim 1, characterized in that, The interface modification layer material is one or more of ethylenediamine hydroiodate, phenylethyl ammonium chloride, or ethylenediamine hydrochloride, with a concentration of 0.5~2 mg / mL.

3. The method for fabricating a perovskite solar cell based on a tin-based perovskite thin film according to claim 1, characterized in that, The hole transport layer material is poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid PEDOT:PSS; Spin coat at 4000~6000 rpm for 40~60 s, then anneal at 120~140 ℃ for 20~30 min.

4. The method for fabricating a perovskite solar cell based on a tin-based perovskite thin film according to claim 1, characterized in that, In step (5), a tin-based perovskite thin film is deposited using an anti-solvent method, including: A perovskite precursor solution with a concentration of 0.8–1.5 mol / L was dropped onto an ITO transparent conductive glass substrate with a hole transport layer material deposited on it. The substrate was then spin-coated at 4000–8000 rpm for 40–80 s in a nitrogen atmosphere. An antisolvent was added in the last 18–25 s, and the substrate was annealed at 100–120 °C for 10–20 min to obtain a tin-based perovskite thin film.

5. The method for fabricating a perovskite solar cell based on a tin-based perovskite thin film according to claim 4, characterized in that, The antisolvent is anhydrous chlorobenzene, toluene, ethyl acetate, or diethyl ether.

6. The method for fabricating a perovskite solar cell based on a tin-based perovskite thin film according to claim 1, characterized in that, In step (6), the interface modification layer material is spin-coated on the tin-based perovskite film at a speed of 4000~6000 rpm for 20~40 s in a nitrogen atmosphere, and then annealed at 100~120 ℃ for 5~10 min.

7. The method for fabricating a perovskite solar cell based on a tin-based perovskite thin film according to claim 1, characterized in that, The electron transport layer is C. 60 The thickness is 20~40 nm; The hole-blocking layer is made of copper bath and has a thickness of 5~10 nm. A metal electrode Ag was deposited by vapor deposition, with a thickness of 80~150 nm.

8. A perovskite solar cell based on a tin-based perovskite thin film prepared by the method according to any one of claims 1-7.

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