A CsSnI3 for perovskite solar cells and its preparation thereof, perovskite solar cells and their preparation thereof

Abstract

This invention provides a CsSnI3 for perovskite solar cells and its preparation, as well as a perovskite solar cell and its preparation method. The preparation method includes: firstly, mixing SnI2 with tri-n-octylphosphine (TOP) to obtain a SnI2-TOP precursor; then, under a protective atmosphere, secondly mixing the obtained SnI2-TOP precursor, Sn powder, and a Cs-containing active solution to obtain CsSnI3 for perovskite solar cells. In the preparation method of CsSnI3 for perovskite solar cells provided by this invention, by mixing SnI2 with tri-n-octylphosphine (TOP) to obtain the SnI2-TOP precursor, and adding Sn powder during the preparation of CsSnI3 from the SnI2-TOP precursor and the Cs-containing active solution, the content of tetravalent Sn can be minimized, thereby ensuring that the final prepared CsSnI3 for perovskite solar cells has higher carrier lifetime and photoluminescence quantum yield.

Description

Technical Field

[0001] This invention belongs to the field of perovskite battery technology, and relates to a method for preparing CsSnI3 for perovskite batteries, particularly to a CsSnI3 for perovskite batteries and its preparation, and perovskite batteries and their preparation. Background Technology

[0002] The power conversion efficiency (PCE) of perovskite solar cells (PSCs) has improved rapidly over the past decade and is quickly approaching that of traditional crystalline silicon solar cells. Therefore, perovskite solar cells are considered one of the most promising alternatives to crystalline silicon solar cells.

[0003] Pb-based perovskites are unstable under conditions of light, high temperature, humidity, and high oxygen, and are prone to decomposition, leading to the release of toxic Pb. 2+ When lead ions enter the environment, they are harmful to humans, animals, and plants. Studies have shown that lead ion pollution of soil and water sources is permanent and can have very serious negative impacts on the survival of humans, animals, and plants.

[0004] Sn and Pb are elements with the same host group, therefore they have the same valence state and similar ionic radii. Consequently, tin-based perovskites exhibit excellent photoelectric properties similar to lead-based perovskites. Furthermore, compared to similar Pb-based materials, Sn-based perovskites also possess a narrower optical band gap (1.2–1.4 eV) and higher carrier mobility. Although tin-based perovskites decompose and release soluble toxic byproducts when exposed to water, fortunately, upon contact with water and air, they spontaneously degrade into non-toxic tin oxide compounds, making them environmentally friendly. It can be seen that tin-based perovskite solar cells are currently the most promising environmentally friendly perovskite solar cells.

[0005] All-inorganic tin-based perovskite (CsSnI3) solar cells exhibit better phase stability, moisture resistance, and optical stability than other types of tin-based perovskite solar cells. However, divalent Sn is easily oxidized to tetravalent Sn, which has a significant impact on crystallization, defects, doping, and even lattice stability.

[0006] CN112397653A discloses a high-efficiency and stable inorganic lead-free perovskite solar cell and its fabrication method. The solar cell comprises, from bottom to top, a conductive substrate, a PEDOT:PSS layer, an inorganic lead-free CsSnI3 perovskite layer, a C60 layer, a BCP layer, and a metal counter electrode layer. The inorganic lead-free CsSnI3 perovskite layer is a CsSnI3 perovskite layer passivated with thiourea-based small-molecule organic compounds. However, in this high-efficiency and stable inorganic lead-free perovskite solar cell, the divalent Sn in the inorganic lead-free CsSnI3 perovskite layer is easily oxidized to tetravalent Sn, resulting in low lattice stability of the CsSnI3 perovskite layer, which is detrimental to the stability of the perovskite solar cell.

[0007] CN115132864A discloses a Y-doped inorganic perovskite CsSnI3 thin film. The film is prepared by spin-coating a CsSnI3 precursor solution containing elemental yttrium (Y) powder, with a SnI2 to Y ratio of 1 mmol: 2–6 mg. This literature describes a CsSnI3 thin film prepared by adding Y powder, which exhibits more than 10 times improved crystallinity compared to undoped CsSnI3 films; significantly increased photoluminescence intensity; improved light absorption in the visible light region, with the band gap increasing from 1.303 eV to 1.337 eV, beneficial for device performance; and reduced roughness from 11 nm to 6.8 nm, beneficial for improving the photoelectric conversion efficiency of solar cells. However, the preparation process of this Y-doped inorganic perovskite CsSnI3 thin film involves the addition of yttrium (Y) powder to the SnI2 / YSnI3 film. 2+ To Sn 4+ The oxidation suppression effect is insufficient, resulting in insufficient stability of the Y-doped inorganic perovskite CsSnI3 film.

[0008] Existing methods for preparing CsSnI3 for perovskite solar cells all have certain drawbacks. One problem is the easy oxidation of divalent Sn to tetravalent Sn, which adversely affects the crystallinity, defects, and lattice stability of the CsSnI3 used in perovskite solar cells, thus degrading the electrochemical performance of the cells. Therefore, developing a novel CsSnI3 for perovskite solar cells, its preparation method, and the perovskite solar cell and its fabrication process is crucial. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a CsSnI3 for perovskite solar cells and its preparation, as well as a perovskite solar cell and its preparation method. In the preparation method of CsSnI3 for perovskite solar cells provided by the present invention, SnI2 is mixed with tri-n-octylphosphine (TOP) to obtain a SnI2-TOP precursor. Sn powder is added during the preparation of CsSnI3 using the SnI2-TOP precursor and a Cs-containing active solution. This minimizes the content of tetravalent Sn and maximizes the content of divalent Sn, thereby ensuring that the final CsSnI3 for perovskite solar cells has higher carrier lifetime and photoluminescence quantum yield, thus improving the electrochemical performance of the perovskite solar cell.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a method for preparing CsSnI3 for perovskite solar cells, the method comprising:

[0012] The SnI2-TOP precursor is obtained by first mixing SnI2 with tri-n-octylphosphine; then, under a protective atmosphere, the SnI2-TOP precursor, Sn powder, and Cs-containing active solution are mixed to obtain CsSnI3 for perovskite batteries.

[0013] In the preparation method of CsSnI3 for perovskite solar cells provided by this invention, SnI2 is mixed with tri-n-octylphosphine (TOP) to obtain a SnI2-TOP precursor. Sn powder is added during the preparation of CsSnI3 from the SnI2-TOP precursor and a Cs-containing active solution. This method can minimize the content of tetravalent Sn and maximize the content of divalent Sn, thereby ensuring that the final CsSnI3 for perovskite solar cells has a higher carrier lifetime and photoluminescence quantum yield, thus improving the electrochemical performance of perovskite solar cells.

[0014] Oxygen and the commonly used solvent ODE (1-octadecene) both drive the rapid oxidation of divalent Sn. Therefore, in this invention, SnI2 is mixed with tri-n-octylphosphine (TOP) to prepare the SnI2-TOP precursor. Sn powder is added during the preparation of CsSnI3 from the SnI2-TOP precursor and a Cs-containing active solution. TOP and Sn powder are used to reverse the oxygen-driven and solvent-driven oxidation. The mechanism is as follows:

[0015] Preferably, the temperature of the first mixing is 80-100°C, and the time is 3-5 hours.

[0016] The temperature of the first mixing in this invention is 80 to 100°C, for example, it can be 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C, 98°C or 100°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0017] The mixing time of the first mixing in this invention is 3 to 5 hours, for example, it can be 3 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, 4 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours or 5 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] Preferably, the first mixing process is accompanied by stirring at a speed of 3000 to 5000 rpm, for example, 3000 rpm, 3200 rpm, 3400 rpm, 3600 rpm, 3800 rpm, 4000 rpm, 4200 rpm, 4400 rpm, 4600 rpm, 4800 rpm or 5000 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0019] Preferably, the solid-liquid ratio of SnI2 to tri-n-octylphosphine in the first mixture is (0.5-1.5):2, for example, it can be 0.5:2, 0.6:2, 0.7:2, 0.8:2, 0.9:2, 1:2, 1.1:2, 1.2:2, 1.3:2, 1.4:2 or 1.5:2, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The unit of solid-liquid ratio is g / mL.

[0020] Preferably, the protective atmosphere includes nitrogen and / or an inert gas.

[0021] Preferably, the temperature of the second mixing is 150–180°C, and the time is 7–10 seconds.

[0022] The temperature of the second mixing in this invention is 150 to 180°C, for example, it can be 150°C, 155°C, 160°C, 165°C, 170°C, 175°C or 180°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] The mixing time of the second mixing in this invention is 7 to 10 seconds, for example, it can be 7 seconds, 7.5 seconds, 8 seconds, 8.5 seconds, 9 seconds, 9.5 seconds or 10 seconds, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] Preferably, the mass ratio of SnI2-TOP precursor, Sn powder and Cs-containing active solution in the second mixture is (7-7.5):(7-7.5):1.

[0025] The mass ratio of the SnI2-TOP precursor to the Cs-containing active solution described in this invention is (7-7.5):1, for example, it can be 7:1, 7.1:1, 7.2:1, 7.3:1, 7.4:1 or 7.5:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] The mass ratio of Sn powder to Cs-containing active solution described in this invention is (7-7.5):1, for example, it can be 7:1, 7.1:1, 7.2:1, 7.3:1, 7.4:1 or 7.5:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] Preferably, the D50 particle size of the Sn powder in the second mixture is 1 to 800 μm, for example, it can be 1 μm, 5 μm, 10 μm, 20 μm, 50 μm, 80 μm, 100 μm, 200 μm, 300 μm, 500 μm or 800 μm, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0028] Preferably, the second mixture is cooled, and the cooling method includes placing the second mixed solution in an ice-water bath.

[0029] Preferably, the method for preparing the Cs-containing active solution includes:

[0030] The third mixture of Cs2CO3, oleic acid, oleylamine, and octadecene is stirred until Cs2CO3 is completely dissolved, resulting in a transparent Cs-containing active solution.

[0031] Preferably, in the third mixture, the solid-liquid ratio of Cs2CO3 to oleic acid is (0.5-1.5):2, the solid-liquid ratio of Cs2CO3 to oleylamine is (0.5-1.5):2, and the solid-liquid ratio of Cs2CO3 to octadecene is (0.5-1.5):60, with the unit of solid-liquid ratio being g / mL.

[0032] In this invention, the solid-liquid ratio of Cs2CO3 to oleic acid in the third mixture is (0.5-1.5):2, for example, it can be 0.5:2, 0.7:2, 0.9:2, 1.1:2, 1.3:2 or 1.5:2, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] In this invention, the solid-liquid ratio of Cs2CO3 to oleylamine in the third mixture is (0.5-1.5):2, for example, it can be 0.5:2, 0.7:2, 0.9:2, 1.1:2, 1.3:2 or 1.5:2, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] In this invention, the solid-liquid ratio of Cs2CO3 to octadecene in the third mixture is (0.5-1.5):60, for example, it can be 0.5:60, 0.7:60, 0.9:60, 1.1:60, 1.3:60 or 1.5:60, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] Preferably, the third mixing is carried out in a vacuum environment, and the temperature of the third mixing is 100-120°C, for example, 100°C, 102°C, 104°C, 106°C, 108°C, 110°C, 112°C, 114°C, 116°C, 118°C or 120°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0036] Preferably, the third mixing process is accompanied by stirring at a speed of 3000 to 5000 rpm, for example, 3000 rpm, 3200 rpm, 3400 rpm, 3600 rpm, 3800 rpm, 4000 rpm, 4200 rpm, 4400 rpm, 4600 rpm, 4800 rpm or 5000 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0037] Preferably, the preparation method further includes the extraction of CsSnI3 after cooling, wherein the extraction of CsSnI3 includes performing a first extraction and a second extraction in sequence.

[0038] Preferably, the first extraction includes: mixing a fourth mixture of methyl acetate with the cooled solution containing CsSnI3, followed by a first centrifugation to obtain a precipitate.

[0039] Preferably, the volume ratio of methyl acetate to the solution containing CsSnI3 in the fourth mixture is (0.5 to 1.5):1, for example, it can be 0.5:1, 0.7:1, 0.9:1, 1:1, 1.2:1, 1.4:1 or 1.5:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0040] Preferably, the first centrifugation speed is 3000-5000 rpm and the time is 1-3 min.

[0041] The rotational speed of the first centrifuge in this invention is 3000 to 5000 rpm, for example, it can be 3000 rpm, 3200 rpm, 3400 rpm, 3600 rpm, 3800 rpm, 4000 rpm, 4200 rpm, 4400 rpm, 4600 rpm, 4800 rpm or 5000 rpm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] The first centrifugation time of the present invention is 1 to 3 minutes, for example, it can be 1 minute, 1.2 minutes, 1.4 minutes, 1.6 minutes, 1.8 minutes, 2 minutes, 2.2 minutes, 2.4 minutes, 2.6 minutes, 2.8 minutes or 3 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] Preferably, the second extraction includes: mixing the precipitate obtained in the fifth mixture with pure toluene, and then performing a second centrifugation to obtain CsSnI3 for perovskite solar cells.

[0044] Preferably, the solid-liquid ratio of the precipitate to pure toluene in the fifth mixture is (0.5 to 1.5):100, for example, it can be 0.5:100, 0.7:100, 0.9:100, 1:100, 1.2:100, 1.4:100 or 1.5:100, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The unit of solid-liquid ratio is g / mL.

[0045] Preferably, the second centrifugation speed is 3000-5000 rpm and the time is 1-3 min.

[0046] The rotational speed of the second centrifuge in this invention is 3000 to 5000 rpm, for example, it can be 3000 rpm, 3200 rpm, 3400 rpm, 3600 rpm, 3800 rpm, 4000 rpm, 4200 rpm, 4400 rpm, 4600 rpm, 4800 rpm or 5000 rpm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] The second centrifugation time in this invention is 1 to 3 minutes, for example, it can be 1 minute, 1.2 minutes, 1.4 minutes, 1.6 minutes, 1.8 minutes, 2 minutes, 2.2 minutes, 2.4 minutes, 2.6 minutes, 2.8 minutes or 3 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0048] As a preferred embodiment of the preparation method of the present invention, the preparation method includes:

[0049] (1) SnI2 and tri-n-octylphosphine were mixed at 80-100℃ for 3-5 hours. The solid-liquid ratio of SnI2 to tri-n-octylphosphine was (0.5-1.5):2. The unit of the solid-liquid ratio was g / mL. The mixing process was accompanied by stirring at 3000-5000 rpm to obtain SnI2-TOP precursor.

[0050] (2) In a vacuum environment, Cs2CO3, oleic acid, oleylamine and octadecene are mixed at 100-120℃. The solid-liquid ratio of Cs2CO3 to oleic acid is (0.5-1.5):2, the solid-liquid ratio of Cs2CO3 to oleylamine is (0.5-1.5):2, and the solid-liquid ratio of Cs2CO3 to octadecene is (0.5-1.5):60. The unit of solid-liquid ratio is g / mL. During the mixing process, the mixture is stirred at a speed of 3000-5000 rpm until Cs2CO3 is completely dissolved, and a transparent Cs-containing active solution is obtained.

[0051] (3) In nitrogen and / or inert gas, mix the SnI2-TOP precursor obtained in step (1) and Sn powder with D50 particle size of 1 to 800 μm with the Cs active solution obtained in step (2) at 150 to 180 °C for 7 to 10 seconds, and then place it in an ice-water bath for cooling to obtain a solution containing CsSnI3.

[0052] (4) Mix methyl acetate with the solution containing CsSnI3 obtained in step (3) at a volume ratio of (0.5-1.5):1, and centrifuge at 3000-5000 rpm for 1-3 min to obtain a precipitate; then mix the precipitate with pure toluene at a solid-liquid ratio of (0.5-1.5):100, where the unit of solid-liquid ratio is g / mL, and centrifuge at 3000-5000 rpm for 1-3 min to obtain CsSnI3 for perovskite solar cells.

[0053] In a second aspect, the present invention provides a CsSnI3 for perovskite solar cells, wherein the CsSnI3 for perovskite solar cells is obtained by the preparation method described in the first aspect.

[0054] Thirdly, the present invention provides a fabrication process for perovskite solar cells, the fabrication process comprising:

[0055] After depositing an electron transport layer on the substrate surface, a CsSnI3 perovskite layer is deposited on the surface of the electron transport layer using CsSnI3 as described in the second aspect. Then, a hole transport layer and a metal electrode are sequentially deposited on the surface of the obtained CsSnI3 perovskite layer to obtain a perovskite solar cell.

[0056] Preferably, the method for depositing the CsSnI3 perovskite layer includes:

[0057] The CsSnI3 was dissolved in a solvent to obtain a CsSnI3 solution, which was then coated onto the surface of the electron transport layer and subjected to heat treatment to obtain a CsSnI3 perovskite layer.

[0058] Preferably, the solvent comprises a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of (8-10):1. The volume ratio of N,N-dimethylformamide to dimethyl sulfoxide can be, for example, 8:1, 8.2:1, 8.4:1, 8.6:1, 9:1, 9.2:1, 9.4:1, 9.6:1 or 10:1, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0059] Preferably, the concentration of CsSnI3 in the CsSnI3 solution is 0.3 to 0.7 mol / L, for example, it can be 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, 0.5 mol / L, 0.55 mol / L, 0.6 mol / L, 0.65 mol / L or 0.7 mol / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0060] Preferably, the dissolution method includes stirring at 15–30°C for 4–8 hours.

[0061] The dissolution process described in this invention involves stirring at 15–30°C, for example, 15°C, 17°C, 20°C, 22°C, 25°C, 27°C, or 30°C, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0062] The stirring time during dissolution described in this invention is 4 to 8 hours, for example, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, or 8 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0063] Preferably, filtration is further included between the dissolution and the coating.

[0064] Preferably, the coating method includes spin coating, and the spin coating speed is 4000 to 6000 rpm, for example, 4000 rpm, 4200 rpm, 4400 rpm, 4600 rpm, 4800 rpm, 5000 rpm, 5200 rpm, 5400 rpm, 5600 rpm, 5800 rpm or 6000 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0065] Preferably, the heat treatment temperature is 120–180°C and the time is 5–15 min.

[0066] The heat treatment temperature described in this invention is 120 to 180°C, for example, it can be 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C or 180°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0067] The heat treatment time described in this invention is 5 to 15 minutes, for example, it can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes or 15 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0068] Preferably, the method for depositing the CsSnI3 perovskite layer further includes vapor deposition.

[0069] Fourthly, the present invention provides a perovskite battery, wherein the perovskite battery is obtained by the preparation process described in the third aspect;

[0070] The perovskite solar cell comprises a substrate, an electron transport layer, a CsSnI3 perovskite layer, a hole transport layer, and a metal electrode, which are stacked sequentially.

[0071] Preferably, the thickness of the electron transport layer is 10 to 20 nm, for example, it can be 10 nm, 12 nm, 14 nm, 16 nm, 18 nm or 20 nm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0072] Preferably, the thickness of the CsSnI3 perovskite layer is 400–600 nm, for example, it can be 400 nm, 420 nm, 440 nm, 460 nm, 480 nm, 500 nm, 520 nm, 540 nm, 560 nm, 580 nm or 600 nm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0073] Preferably, the thickness of the hole transport layer is 15 to 25 nm, for example, it can be 15 nm, 17 nm, 19 nm, 20 nm, 21 nm, 23 nm or 25 nm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0074] Preferably, the thickness of the metal electrode is 110 to 130 nm, for example, it can be 110 nm, 112 nm, 114 nm, 116 nm, 118 nm, 120 nm, 122 nm, 124 nm, 126 nm, 128 nm or 130 nm, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0075] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0076] Compared with the prior art, the present invention has the following beneficial effects:

[0077] In the preparation method of CsSnI3 for perovskite solar cells provided by this invention, SnI2 is mixed with tri-n-octylphosphine (TOP) to obtain a SnI2-TOP precursor. Sn powder is added during the preparation of CsSnI3 from the SnI2-TOP precursor and a Cs-containing active solution. This method can minimize the content of tetravalent Sn and maximize the content of divalent Sn, thereby ensuring that the final CsSnI3 for perovskite solar cells has a higher carrier lifetime and photoluminescence quantum yield, thus improving the electrochemical performance of perovskite solar cells. Attached Figure Description

[0078] Figure 1 These are schematic diagrams of perovskite solar cells prepared in the application examples and comparative application examples.

[0079] Figure 2 The curves show the change in photoluminescence intensity of the perovskite solar cells prepared in Application Example 2 and Comparative Example 3 as a function of wavelength.

[0080] Figure 3 These are transient fluorescence spectra of the perovskite solar cells prepared in Application Example 2 and Comparative Example 3.

[0081] Wherein, 1-conductive substrate; 2-titanium dioxide electron transport layer; 3-CsSnI3 perovskite layer; 4-hole transport layer; 5-silver electrode. Detailed Implementation

[0082] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0083] Example 1

[0084] This embodiment provides a method for preparing CsSnI3 for perovskite solar cells, the method comprising:

[0085] (1) SnI2 and tri-n-octylphosphine were mixed at 90℃ for 4h. The solid-liquid ratio of SnI2 to tri-n-octylphosphine was 1:2. The unit of the solid-liquid ratio was g / mL. The mixing process was accompanied by stirring at 4000rpm to obtain SnI2-TOP precursor.

[0086] (2) In a vacuum environment, Cs2CO3, oleic acid, oleylamine and octadecene were mixed at 110℃. The solid-liquid ratio of Cs2CO3 to oleic acid was 1:2, the solid-liquid ratio of Cs2CO3 to oleylamine was 1:2, and the solid-liquid ratio of Cs2CO3 to octadecene was 1:60. The unit of solid-liquid ratio is g / mL. During the mixing process, the mixture was stirred at 4000 rpm until Cs2CO3 was completely dissolved, and a transparent Cs-containing active solution was obtained.

[0087] (3) In a nitrogen atmosphere, mix the SnI2-TOP precursor obtained in step (1) and Sn powder with a D50 particle size of 20 μm with the Cs active solution obtained in step (2) at 160 °C with a mass ratio of 7.2:7.2:1, and then place it in an ice-water bath for cooling to obtain a solution containing CsSnI3.

[0088] (4) Mix methyl acetate in a volume ratio of 1:1 with the solution containing CsSnI3 obtained in step (3), and centrifuge at 4000 rpm for 2 min to obtain a precipitate; then mix the precipitate with pure toluene, the solid-liquid ratio of the precipitate to pure toluene is 1:100, the unit of solid-liquid ratio is g / mL, and centrifuge at 4000 rpm for 2 min to obtain CsSnI3 for perovskite solar cells.

[0089] Example 2

[0090] This embodiment provides a method for preparing CsSnI3 for perovskite solar cells, the method comprising:

[0091] (1) SnI2 and tri-n-octylphosphine were mixed at 80℃ for 5h. The solid-liquid ratio of SnI2 to tri-n-octylphosphine was 0.5:2. The unit of the solid-liquid ratio was g / mL. The mixing process was accompanied by stirring at 5000rpm to obtain SnI2-TOP precursor.

[0092] (2) In a vacuum environment, Cs2CO3, oleic acid, oleylamine and octadecene were mixed at 120°C. The solid-liquid ratio of Cs2CO3 to oleic acid was 1.5:2, the solid-liquid ratio of Cs2CO3 to oleylamine was 1.5:2, and the solid-liquid ratio of Cs2CO3 to octadecene was 1.5:60. The unit of solid-liquid ratio is g / mL. During the mixing process, the mixture was stirred at 3000 rpm until Cs2CO3 was completely dissolved, and a transparent Cs-containing active solution was obtained.

[0093] (3) In nitrogen and / or inert gas, mix the SnI2-TOP precursor obtained in step (1) with Sn powder with a D50 particle size of 100 μm and the Cs-containing active solution obtained in step (2) in a mass ratio of 7:7:1 at 150°C for 7s, and then place it in an ice-water bath for cooling to obtain a solution containing CsSnI3.

[0094] (4) After mixing methyl acetate at a volume ratio of 0.5:1 with the solution containing CsSnI3 obtained in step (3), centrifuge at 3000 rpm for 3 min to obtain a precipitate; then mix the precipitate with pure toluene, the solid-liquid ratio of the precipitate to pure toluene is 1.5:100, the unit of solid-liquid ratio is g / mL, and centrifuge at 3000 rpm for 3 min to obtain CsSnI3 for perovskite solar cells.

[0095] Example 3

[0096] This embodiment provides a method for preparing CsSnI3 for perovskite solar cells, the method comprising:

[0097] (1) SnI2 and tri-n-octylphosphine were mixed at 100℃ for 3h. The solid-liquid ratio of SnI2 to tri-n-octylphosphine was 1.5:2. The unit of the solid-liquid ratio was g / mL. The mixing process was accompanied by stirring at 3000rpm to obtain SnI2-TOP precursor.

[0098] (2) In a vacuum environment, Cs2CO3, oleic acid, oleylamine and octadecene were mixed at 100°C. The solid-liquid ratio of Cs2CO3 to oleic acid was 0.5:2, the solid-liquid ratio of Cs2CO3 to oleylamine was 0.5:2, and the solid-liquid ratio of Cs2CO3 to octadecene was 0.5:60. The unit of solid-liquid ratio is g / mL. During the mixing process, the mixture was stirred at 5000 rpm until Cs2CO3 was completely dissolved, and a transparent Cs-containing active solution was obtained.

[0099] (3) In nitrogen and / or inert gas, mix the SnI2-TOP precursor obtained in step (1) and Sn powder with a D50 particle size of 300 μm with the Cs active solution obtained in step (2) at 180 °C with a mass ratio of 7.5:7.5:1 for 10 s, and then place it in an ice-water bath for cooling to obtain a solution containing CsSnI3.

[0100] (4) After mixing methyl acetate in a volume ratio of 1.5:1 with the solution containing CsSnI3 obtained in step (3), centrifuge at 5000 rpm for 1 min to obtain a precipitate; then mix the precipitate with pure toluene, the solid-liquid ratio of the precipitate to pure toluene is 0.5:100, the unit of solid-liquid ratio is g / mL, and centrifuge at 5000 rpm for 1 min to obtain CsSnI3 for perovskite solar cells.

[0101] Example 4

[0102] This embodiment provides a method for preparing CsSnI3 for perovskite solar cells. Except for step (1), where the solid-liquid ratio of SnI2 to tri-n-octylphosphine is 0.2:2 and the unit of the solid-liquid ratio is g / mL, all other steps are the same as in Example 1.

[0103] Example 5

[0104] This embodiment provides a method for preparing CsSnI3 for perovskite solar cells. Except for step (1), where the solid-liquid ratio of SnI2 to tri-n-octylphosphine is 1.8:2 and the unit of solid-liquid ratio is g / mL, all other steps are the same as in Example 1.

[0105] Example 6

[0106] This embodiment provides a method for preparing CsSnI3 for perovskite solar cells. Except for the mixing temperature of SnI2 and tri-n-octylphosphine in step (1) being 60°C, the rest is the same as in Example 1.

[0107] Example 7

[0108] This embodiment provides a method for preparing CsSnI3 for perovskite solar cells. Except for the mixing temperature of SnI2 and tri-n-octylphosphine in step (1) being 120°C, the rest is the same as in Example 1.

[0109] Example 8

[0110] This embodiment provides a method for preparing CsSnI3 for perovskite solar cells. Except for the mass ratio of SnI2-TOP precursor and Sn powder obtained in step (1) to Cs-containing active solution obtained in step (2) being 6.5:7.2:1, the rest is the same as in Example 1.

[0111] Example 9

[0112] This embodiment provides a method for preparing CsSnI3 for perovskite solar cells. Except for the mass ratio of SnI2-TOP precursor and Sn powder obtained in step (1) to Cs-containing active solution obtained in step (2) being 8:7.2:1, the rest is the same as in Example 1.

[0113] Comparative Example 1

[0114] This comparative example provides a method for preparing CsSnI3 for perovskite solar cells. Except for omitting step (1) and directly mixing SnI2 and Sn powder with a Cs-containing active solution in step (3), the rest is the same as in Example 1.

[0115] Comparative Example 2

[0116] This comparative example provides a method for preparing CsSnI3 for perovskite solar cells. Except for omitting the Sn powder mixed in step (3), the method is the same as in Example 1.

[0117] Application Example 1

[0118] This application example provides a fabrication process for perovskite solar cells using CsSnI3 provided in Example 1. The fabrication process includes:

[0119] (1) ITO glass was used as the conductive substrate 1, and the ITO glass was ultrasonically cleaned for 15 minutes in sequence with glass cleaner, deionized water, ethanol, acetone, isopropanol and ethanol. Then the ITO glass was dried with dry air and then treated with ultraviolet-ozone for 20 minutes.

[0120] (2) 0.15 mol / L of titanium diisopropoxide (acetylacetone) was placed in 1-butanol solution (75% w / w isopropanol, Aldrich) to obtain a mixture. The mixture was then spin-coated onto ITO glass at 2500 rpm and heated at 125°C for 5 min to obtain a titanium dioxide electron transport layer 2 with a thickness of 15 nm.

[0121] (3) The CsSnI3 described in Example 1 was dissolved in a solvent (a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 9:1) by stirring at 20°C for 6 hours and then filtered to obtain a CsSnI3 solution with a concentration of 0.5 mol / L. The obtained CsSnI3 solution was then spin-coated onto the surface of the titanium dioxide electron transport layer 2 at a speed of 5000 rpm and then heat-treated at 150°C for 10 minutes to obtain a CsSnI3 perovskite layer 3 with a thickness of 500 nm.

[0122] (4) Li-TFSI was dissolved in acetonitrile to prepare a 520 mg / mL Li-TFSI acetonitrile solution. Then, 72.3 mg of Spiro-OMeTAD powder, 28.8 μL of TBP solution (tributyl phosphate solution) and 17.5 μL of Li-TFSI solution were dissolved in 1 mL of chlorobenzene and stirred to prepare 1 mL of Spiro-OMeTAD solution. The prepared Spiro-OMeTAD solution was spin-coated onto the perovskite surface using a spin-coating method at 3000 rpm to obtain a hole transport layer 4 with a thickness of 20 nm.

[0123] (5) A 120 nm thick silver electrode 5 was vacuum deposited using a thermal evaporation method to obtain the following: Figure 1 The perovskite solar cell shown.

[0124] Application Example 2

[0125] This application example provides a preparation process for preparing perovskite solar cells using CsSnI3 provided in Example 1. Except for the CsSnI3 solution with a concentration of 0.6 mol / L obtained after filtration in step (3), the rest is the same as in Application Example 1.

[0126] Application Example 3

[0127] This application example provides a preparation process for preparing perovskite solar cells using CsSnI3 provided in Example 1. Except for the CsSnI3 solution with a concentration of 0.7 mol / L obtained after filtration in step (3), the rest is the same as in Application Example 1.

[0128] Application Example 4

[0129] This application example provides a fabrication process for perovskite solar cells using the CsSnI3 provided in Example 1, except that step (3) is replaced by: depositing the CsSnI3 provided in Example 1 onto the surface of the titanium dioxide electron transport layer 2 by vapor deposition, with a vapor deposition rate of [missing information]. Except for obtaining a perovskite layer with a thickness of 180 nm, everything else was the same as in Example 1.

[0130] Application Example 5

[0131] This application example provides a fabrication process for perovskite solar cells using the CsSnI3 provided in Example 1, except that step (3) is replaced by: depositing the CsSnI3 provided in Example 1 onto the surface of the titanium dioxide electron transport layer 2 by vapor deposition, with a vapor deposition rate of [missing information]. Except for obtaining a perovskite layer with a thickness of 200 nm, everything else was the same as in Example 1.

[0132] Application Example 6

[0133] This application example provides a fabrication process for perovskite solar cells using the CsSnI3 provided in Example 1, except that step (3) is replaced by: depositing the CsSnI3 provided in Example 1 onto the surface of the titanium dioxide electron transport layer 2 by vapor deposition, with a vapor deposition rate of [missing information]. Except for obtaining a perovskite layer with a thickness of 220 nm, everything else was the same as in Example 1.

[0134] Application Example 7

[0135] This application example provides a fabrication process for perovskite solar cells using CsSnI3 as provided in Example 2. The fabrication process includes:

[0136] (1) ITO glass was used as the conductive substrate 1, and the ITO glass was ultrasonically cleaned for 15 minutes in sequence with glass cleaner, deionized water, ethanol, acetone, isopropanol and ethanol. Then the ITO glass was dried with dry air and then treated with ultraviolet-ozone for 20 minutes.

[0137] (2) 0.15 mol / L of titanium diisopropoxide (acetylacetone) was placed in 1-butanol solution (75% w / w isopropanol, Aldrich) to obtain a mixture. The mixture was then spin-coated onto ITO glass at 2500 rpm and heated at 125°C for 5 min to obtain a titanium dioxide electron transport layer 2 with a thickness of 10 nm.

[0138] (3) The CsSnI3 described in Example 2 was dissolved in a solvent (a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 8:1) by stirring at 15°C for 8 hours and then filtered to obtain a CsSnI3 solution with a concentration of 0.7 mol / L. The obtained CsSnI3 solution was then spin-coated onto the surface of the titanium dioxide electron transport layer 2 at a speed of 6000 rpm and then heat-treated at 120°C for 15 min to obtain a CsSnI3 perovskite layer 3 with a thickness of 600 nm.

[0139] (4) Li-TFSI was dissolved in acetonitrile to prepare a 520 mg / mL Li-TFSI acetonitrile solution. Then, 72.3 mg of Spiro-OMeTAD powder, 28.8 μL of TBP solution (tributyl phosphate solution) and 17.5 μL of Li-TFSI solution were dissolved in 1 mL of chlorobenzene and stirred to prepare 1 mL of Spiro-OMeTAD solution. The prepared Spiro-OMeTAD solution was spin-coated onto the perovskite surface at 3000 rpm to obtain a hole transport layer 4 with a thickness of 15 nm.

[0140] (5) A 120 nm thick silver electrode 5 was vacuum deposited using a thermal evaporation method to obtain a perovskite solar cell.

[0141] Application Example 8

[0142] This application example provides a fabrication process for perovskite solar cells using CsSnI3 provided in Example 3. The fabrication process includes:

[0143] (1) ITO glass was used as the conductive substrate 1, and the ITO glass was ultrasonically cleaned for 15 minutes in sequence with glass cleaner, deionized water, ethanol, acetone, isopropanol and ethanol. Then the ITO glass was dried with dry air and then treated with ultraviolet-ozone for 20 minutes.

[0144] (2) 0.15 mol / L of titanium diisopropoxide (acetylacetone) was placed in 1-butanol solution (75% w / w isopropanol, Aldrich) to obtain a mixture. The mixture was then spin-coated onto ITO glass at 2500 rpm and heated at 125°C for 5 min to obtain a titanium dioxide electron transport layer 2 with a thickness of 20 nm.

[0145] (3) The CsSnI3 described in Example 3 was dissolved in a solvent (a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 10:1) by stirring at 30°C for 4 hours and then filtered to obtain a CsSnI3 solution with a concentration of 0.3 mol / L. The obtained CsSnI3 solution was then spin-coated onto the surface of the titanium dioxide electron transport layer 2 at a speed of 4000 rpm and then heat-treated at 180°C for 5 minutes to obtain a CsSnI3 perovskite layer 3 with a thickness of 400 nm.

[0146] (4) Li-TFSI was dissolved in acetonitrile to prepare a 520 mg / mL Li-TFSI acetonitrile solution. Then, 72.3 mg of Spiro-OMeTAD powder, 28.8 μL of TBP solution (tributyl phosphate solution) and 17.5 μL of Li-TFSI solution were dissolved in 1 mL of chlorobenzene and stirred to prepare 1 mL of Spiro-OMeTAD solution. The prepared Spiro-OMeTAD solution was spin-coated onto the perovskite surface at 3000 rpm to obtain a hole transport layer 4 with a thickness of 15 nm.

[0147] (5) A 120 nm thick silver electrode 5 was vacuum deposited using a thermal evaporation method to obtain a perovskite solar cell.

[0148] Application Example 9

[0149] This application example provides a fabrication process for perovskite solar cells using CsSnI3 provided in Example 4. Except for replacing CsSnI3 in Example 1 with CsSnI3 in Example 4 in step (3), the rest is the same as in Application Example 1.

[0150] Application Example 10

[0151] This application example provides a fabrication process for perovskite solar cells using CsSnI3 provided in Example 5. Except for replacing CsSnI3 in Example 1 with CsSnI3 in Example 5 in step (3), the rest is the same as in Application Example 1.

[0152] Application Example 11

[0153] This application example provides a fabrication process for perovskite solar cells using CsSnI3 provided in Example 6. Except for replacing CsSnI3 in Example 1 with CsSnI3 in Example 6 in step (3), the rest is the same as in Application Example 1.

[0154] Application Example 12

[0155] This application example provides a fabrication process for perovskite solar cells using CsSnI3 provided in Example 7. Except for replacing CsSnI3 in Example 1 with CsSnI3 in Example 7 in step (3), the rest is the same as in Application Example 1.

[0156] Application Example 13

[0157] This application example provides a fabrication process for perovskite solar cells using CsSnI3 provided in Example 8. Except for replacing CsSnI3 in Example 1 with CsSnI3 in Example 8 in step (3), the rest is the same as in Application Example 1.

[0158] Application Example 14

[0159] This application example provides a fabrication process for perovskite solar cells using CsSnI3 provided in Example 9. Except for replacing CsSnI3 in Example 1 with CsSnI3 in Example 9 in step (3), the rest is the same as in Application Example 1.

[0160] Comparative Application Example 1

[0161] This comparative application example provides a fabrication process for perovskite solar cells using CsSnI3 provided in Comparative Example 1. Except for replacing CsSnI3 in Example 1 in step (3) with CsSnI3 in Comparative Example 1, the rest is the same as in Application Example 1.

[0162] Comparative Application Example 2

[0163] This comparative application example provides a fabrication process for perovskite solar cells using CsSnI3 provided in Comparative Example 2. Except for replacing CsSnI3 in Example 1 in step (3) with CsSnI3 in Comparative Example 2, the process is the same as in Application Example 1.

[0164] Comparative Application Example 3

[0165] This comparative application example provides a perovskite solar cell fabrication process, except that step (3) is replaced by: dissolving cesium iodide and SnI2 in 1 mL of DMSO solution to prepare a CsSnI3 precursor solution (the concentration of cesium iodide is 0.8 mol / L and the concentration of SnI2 is 0.8 mol / L), stirring the CsSnI3 precursor solution at room temperature for 6 hours and filtering it, then spin-coating it onto the surface of the titanium dioxide electron transport layer 2 at a speed of 5000 rpm, and then annealing the perovskite substrate at 150 °C for 10 min. After annealing, the sample is transferred to a glove box to obtain a CsSnI3 perovskite layer 3 with a thickness of 500 nm. The rest is the same as in Example 1.

[0166] The test environment was controlled at 25°C using a cooling controller. The perovskite solar cells provided in the above embodiments and comparative examples were tested for open circuit voltage (Voc), short circuit current (Jsc), fill factor (FF), and photoelectric conversion efficiency (PCE) using a solar simulator and an IV tester. The current and voltage were collected by a source meter, and the solar simulator illumination intensity needed to be calibrated using a "standard cell" (standard performance solar cell). The final test results of the perovskite solar cells are shown in Table 1.

[0167] The perovskite solar cell fabrication process provided in Application Example 2 and Comparative Application Example 3 yields perovskite solar cells with photoluminescence intensity varying with wavelength, as shown in the curves below. Figure 2 As shown, the transient fluorescence spectrum test diagram is as follows: Figure 3 As shown.

[0168] Table 1

[0169]

[0170]

[0171] From Table 1, we can obtain:

[0172] (1) The perovskite solar cells prepared in Examples 1 to 8 of this invention have higher open-circuit voltage, short-circuit current, fill factor and photoelectric conversion efficiency, and therefore have better electrochemical performance;

[0173] (2) By comparing Application Example 1 with Application Examples 9 and 10, it can be seen that the solid-liquid ratio of SnI2 to tri-n-octylphosphine during the preparation of CsSnI3 affects the performance of the perovskite battery. When the solid-liquid ratio of SnI2 to tri-n-octylphosphine is (0.5~1.5):2, and the unit of solid-liquid ratio is g / mL, the perovskite battery has better performance. This is because when the solid-liquid ratio of SnI2 to tri-n-octylphosphine is (0.5~1.5):2, the synthesized CsSnI3 is purer and has fewer impurities.

[0174] (3) By comparing Application Example 1 with Application Examples 11 and 12, it can be seen that the mixing temperature of SnI2 and tri-n-octylphosphine during the preparation of CsSnI3 affects the performance of the perovskite battery. When the mixing temperature of SnI2 and tri-n-octylphosphine is 80-100℃, the perovskite battery has better performance. This is because when the mixing temperature of SnI2 and tri-n-octylphosphine is 80-100℃, the synthesized CsSnI3 is purer and has fewer impurities.

[0175] (4) By comparing Application Example 1 with Application Examples 13 and 14, it can be seen that the mass ratio of SnI2-TOP precursor, Sn powder and Cs-containing active solution during the preparation of CsSnI3 affects the performance of perovskite battery. When the mass ratio of SnI2-TOP precursor, Sn powder and Cs-containing active solution is 7.2:7.2:1, the perovskite battery has better performance. This is because when the mass ratio of SnI2-TOP precursor, Sn powder and Cs-containing active solution is 7.2:7.2:1, the synthesized CsSnI3 is purer and has fewer impurities.

[0176] (5) By comparing Application Example 1 with Comparative Application Examples 1 to 3, it can be seen that in the preparation method of CsSnI3 for perovskite batteries provided by the present invention, SnI2 is mixed with tri-n-octylphosphine (TOP) to obtain SnI2-TOP precursor, and Sn powder is added in the process of preparing CsSnI3 with SnI2-TOP precursor and Cs-containing active solution. This can minimize the content of tetravalent Sn and maximize the content of divalent Sn, thereby ensuring that the CsSnI3 for perovskite batteries prepared in the end has higher carrier lifetime and photoluminescence quantum yield, thereby improving the electrochemical performance of perovskite batteries.

[0177] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing CsSnI3 for perovskite solar cells, characterized in that, The preparation method includes: The SnI2-TOP precursor is obtained by first mixing SnI2 with tri-n-octylphosphine; then, under a protective atmosphere, the SnI2-TOP precursor, Sn powder, and Cs-containing active solution are mixed to obtain CsSnI3 for perovskite batteries.

2. The preparation method according to claim 1, characterized in that, The temperature of the first mixing is 80–100°C, and the time is 3–5 hours; Preferably, the solid-liquid ratio of SnI2 to tri-n-octylphosphine in the first mixture is (0.5-1.5):2, and the unit of solid-liquid ratio is g / mL.

3. The preparation method according to claim 1 or 2, characterized in that, The second mixing temperature is 150–180°C, and the time is 7–10 seconds; Preferably, the mass ratio of SnI2-TOP precursor, Sn powder and Cs-containing active solution in the second mixture is (7-7.5):(7-7.5):1; Preferably, the D50 particle size of the Sn powder in the second mixture is 1–800 μm; Preferably, the second mixture is cooled, and the cooling method includes placing the second mixed solution in an ice-water bath.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The method for preparing the Cs-containing active solution includes: The third mixture of Cs2CO3, oleic acid, oleylamine and octadecene is stirred until Cs2CO3 is completely dissolved, resulting in a transparent Cs-containing active solution. Preferably, in the third mixture, the solid-liquid ratio of Cs2CO3 to oleic acid is (0.5-1.5):2, the solid-liquid ratio of Cs2CO3 to oleylamine is (0.5-1.5):2, and the solid-liquid ratio of Cs2CO3 to octadecene is (0.5-1.5):60, with the unit of solid-liquid ratio being g / mL; Preferably, the third mixing is carried out in a vacuum environment, and the temperature of the third mixing is 100-120°C.

5. The preparation method according to claim 3, characterized in that, The preparation method further includes the extraction of CsSnI3 after cooling, wherein the extraction of CsSnI3 includes performing a first extraction and a second extraction in sequence; Preferably, the first extraction includes: mixing the fourth mixed methyl acetate with the cooled solution containing CsSnI3, followed by a first centrifugation to obtain a precipitate; Preferably, the second extraction includes: mixing the precipitate obtained in the fifth mixture with pure toluene, and then performing a second centrifugation to obtain CsSnI3 for perovskite solar cells.

6. The preparation method according to any one of claims 1 to 5, characterized in that, The preparation method includes: (1) SnI2 and tri-n-octylphosphine were mixed at 80-100℃ for 3-5 hours. The solid-liquid ratio of SnI2 to tri-n-octylphosphine was (0.5-1.5):

2. The unit of the solid-liquid ratio was g / mL. The mixing process was accompanied by stirring at 3000-5000 rpm to obtain SnI2-TOP precursor. (2) In a vacuum environment, Cs2CO3, oleic acid, oleylamine and octadecene are mixed at 100-120℃. The solid-liquid ratio of Cs2CO3 to oleic acid is (0.5-1.5):2, the solid-liquid ratio of Cs2CO3 to oleylamine is (0.5-1.5):2, and the solid-liquid ratio of Cs2CO3 to octadecene is (0.5-1.5):

60. The unit of solid-liquid ratio is g / mL. During the mixing process, the mixture is stirred at a speed of 3000-5000 rpm until Cs2CO3 is completely dissolved, and a transparent Cs-containing active solution is obtained. (3) In nitrogen and / or inert gas, mix the SnI2-TOP precursor and Sn powder obtained in step (1) with the Cs-containing active solution obtained in step (2) at a mass ratio of (7-7.5):(7-7.5):1 for 7-10 seconds in a nitrogen and / or inert gas at 150-180℃, and then cool them in an ice-water bath to obtain a solution containing CsSnI3. (4) Mix methyl acetate with the solution containing CsSnI3 obtained in step (3) at a volume ratio of (0.5-1.5):1, and centrifuge at 3000-5000 rpm for 1-3 min to obtain a precipitate; then mix the precipitate with pure toluene at a solid-liquid ratio of (0.5-1.5):100, where the unit of solid-liquid ratio is g / mL, and centrifuge at 3000-5000 rpm for 1-3 min to obtain CsSnI3 for perovskite solar cells.

7. A CsSnI3 for perovskite solar cells, characterized in that, The CsSnI3 in the perovskite solar cell is obtained by the preparation method described in any one of claims 1 to 6.

8. A fabrication process for a perovskite solar cell, characterized in that, The preparation process includes: After depositing an electron transport layer on the substrate surface, a CsSnI3 perovskite layer is deposited on the surface of the electron transport layer using CsSnI3 as the raw material described in claim 7. Then, a hole transport layer and a metal electrode are sequentially deposited on the surface of the obtained CsSnI3 perovskite layer to obtain a perovskite solar cell.

9. The preparation process according to claim 8, characterized in that, The method for depositing the CsSnI3 perovskite layer includes: The CsSnI3 was dissolved in a solvent to obtain a CsSnI3 solution. The obtained CsSnI3 solution was then coated on the surface of the electron transport layer and subjected to heat treatment to obtain a CsSnI3 perovskite layer. Preferably, the concentration of CsSnI3 in the CsSnI3 solution is 0.3–0.7 mol / L; Preferably, the heat treatment temperature is 120–180°C and the time is 5–15 min; Preferably, the method for depositing the CsSnI3 perovskite layer further includes vapor deposition.

10. A perovskite solar cell, characterized in that, The perovskite solar cell is obtained by the preparation process described in claim 8 or 9; The perovskite solar cell comprises a substrate, an electron transport layer, a CsSnI3 perovskite layer, a hole transport layer, and a metal electrode, which are stacked sequentially.

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