A method for fabricating tin-based perovskite solar cells

Abstract

This invention provides a method for preparing a tin-based perovskite solar cell, comprising: forming an electron transport layer or a hole transport layer on a substrate surface; forming a perovskite thin film on the surface of the electron transport layer or hole transport layer; performing a reduction treatment by dropping a hydrazine-methylamine solution onto the surface of the perovskite thin film to obtain a reduction product; forming a hole transport layer or an electron transport layer on the surface of the reduction product; and forming a current collector on the surface of the hole transport layer or electron transport layer to obtain a tin-based perovskite solar cell; wherein the hydrazine-methylamine solution comprises hydrazine hydrate, CaCl2, and methylamine. This invention uses a low-concentration hydrazine solution as a reducing agent to reduce the surface layer of the tin-based perovskite, which can eliminate the Sn present in the perovskite. 4+ Meanwhile, a uniform 0-valent Sn protective layer is formed on the surface of the perovskite, which also has a conductive effect, thus improving the stability of the battery while ensuring its photoelectric conversion efficiency.

Description

Technical Field

[0001] This invention belongs to the field of energy material preparation technology, and particularly relates to a method for preparing tin-based perovskite solar cells, specifically a method for improving the stability of tin-based perovskite solar cells based on hydrazine reduction treatment. Background Technology

[0002] Solar cell technology is one of the core technologies in the solar energy field. Due to limitations in cost, energy consumption, and efficiency, the development of traditional crystalline silicon solar cells faces difficulties, necessitating the development of new solar cells with high efficiency, high stability, and low cost. ABX3 type halide perovskite materials possess high light absorption coefficients, long carrier lifetimes, and suitable band gaps (~1.6 eV), making them a promising photovoltaic material.

[0003] Halide perovskite solar cells commonly use materials such as lead methylamine iodide (MAPbI3) and lead formamidinium bromide (FAPbBr3). Lead halides have high light absorption, and their band gap (~1.55 eV) is close to the optimal band gap (1.34 eV) corresponding to the Shockley-Queisser limit. However, due to the toxicity and pollution caused by lead, lead-containing perovskites pose significant environmental problems, making the development of lead-free perovskites imperative. It is generally believed that tin-based halide perovskites have the best overall performance among lead-free perovskites, but Sn... 2+ It is easily oxidized to Sn during production and use. 4+ This leads to severe alteration, deactivation, and device failure in tin-based perovskites; therefore, how to stabilize Sn 2+ This is a problem that urgently needs to be solved. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for preparing tin-based perovskite solar cells. The method provided by this invention has low cost, simple process, and good stabilization effect.

[0005] This invention provides a method for preparing a tin-based perovskite solar cell, comprising:

[0006] An electron transport layer or hole transport layer is formed on the substrate surface;

[0007] A perovskite thin film is formed on the surface of the electron transport layer or hole transport layer;

[0008] A hydrazine-methylamine solution was added dropwise to the surface of the perovskite film for reduction treatment to obtain the reduction product.

[0009] A hole transport layer or an electron transport layer is formed on the surface of the reduction product;

[0010] A current collector is formed on the surface of the hole transport layer or electron transport layer to obtain a tin-based perovskite solar cell.

[0011] The hydrazine-methylamine solution comprises: hydrazine hydrate, CaCl2, and methylamine.

[0012] Preferably, the method for preparing the hydrazine-methylamine solution includes:

[0013] Hydrazine hydrate, CaCl2 and methylamine are mixed, and the CaCl2 in the resulting mixture is removed to obtain a hydrazine-methylamine solution.

[0014] The amount of CaCl2 used is not less than 10 times the mass of hydrazine hydrate;

[0015] The amount of methylamine used is not less than 100 times the mass of hydrazine hydrate.

[0016] Preferably, the mixing method is selected from any one or more combinations of ultrasound, oscillation, stirring, and heating;

[0017] The method for removing CaCl2 from the resulting mixture is selected from any one or a combination of natural precipitation, centrifugation, or filtration.

[0018] Preferably, the method for the reduction process includes:

[0019] A hydrazine-methylamine solution was dropped onto the surface of the perovskite film, and the film was allowed to stand, dry, and anneal.

[0020] Preferably, the settling time is >1 min;

[0021] The drying method is selected from any one or more combinations of natural air drying, heat drying, forced air drying, and vacuum drying.

[0022] Preferably, the annealing temperature is 100–180°C; and the annealing holding time is >1 min.

[0023] Preferably, the perovskite film is formed from a perovskite precursor solution and an antisolvent.

[0024] Preferably, the solute in the perovskite precursor solution is ASnX3, wherein A is selected from any one or a mixture of methylamine, formamidin, Rb, and Cs, and X is selected from one or a mixture of I, Br, and Cl.

[0025] The solvent in the perovskite precursor solution is selected from any one of DMSO, DMF, or a mixture of both.

[0026] The antisolvent is selected from any one or a mixture of alkanes, halogenated hydrocarbons, dimethyl ether, ethylene glycol dimethyl ether, and dimethyl carbonate.

[0027] Preferably, the method for preparing the perovskite thin film includes:

[0028] A perovskite precursor solution and an antisolvent are sequentially coated on the surface of the electron transport layer or hole transport layer, followed by drying and annealing to obtain a perovskite thin film.

[0029] Preferably, the coating method is selected from any one or more combinations of spin coating, spray coating, blade coating, printing, and dipping.

[0030] The drying method is selected from any one or more combinations of natural air drying, heat drying, forced air drying, and vacuum drying.

[0031] The annealing temperature is 100–180°C; the annealing holding time is >1 min.

[0032] Research has found that for Sn in tin-based perovskite devices 2+ Stabilization includes: incorporating Sr into the material 2+ 、Ge 2+ Rare earth element ions, etc., to inhibit Sn 2+ Oxidation; introducing ionic liquid to cover the surface of the perovskite layer to form a dense coating layer; adding Sn nanoparticles to the perovskite to suppress Sn oxidation. 2+ To Sn 4+ Oxidation; passivating materials such as organic gels and biomass materials are coated onto the perovskite surface to isolate Sn. 2+ Contact with external water and oxygen. However, for Sr 2+ 、Ge 2+ Rare earth element doping methods, these doped ions and Sn 2+ The significant size differences between ions in tin-based perovskites lead to lattice mismatches. This results in limited doping amounts (generally no more than 1%) and easily causes lattice distortion, dangling bonds, vacancies, and other defects, introducing new defect growth centers and carrier recombination centers, negatively impacting device performance. Ionic liquid passivation requires expensive ionic liquids, which are prone to leakage, hindering cost reduction, stability improvement, and environmental friendliness. Nanoparticle passivation makes it difficult to ensure effective contact between Sn nanoparticles and perovskite materials. Using organic gels, biomass, or other materials to create passivation layers significantly impedes charge flow within the material, increasing device resistance, voltage drop, and losses. Furthermore, the aforementioned methods can only suppress the formation of new Sn in tin-based perovskites. 4+ It is impossible to eliminate the Sn that already exists in tin-based perovskites during the preparation process. 4+ Therefore, a new method is needed to uniformly coat the surface of tin-based perovskites with zero-valent Sn, while simultaneously eliminating the Sn that is generated during the preparation of the tin-based perovskites. 4+ Defects, thereby achieving more complete stabilization.

[0033] In this invention, hydrazine is a low-cost, environmentally friendly strong oxidant commonly used in the preparation of metal nanomaterials. This invention employs a low-concentration hydrazine solution as a reducing agent to reduce the surface layer of tin-based perovskite, thereby eliminating the Sn present in the perovskite. 4+ Simultaneously, a uniform 0-valent Sn protective layer is formed on the perovskite surface. This protective layer also has conductive properties, improving the stability of the battery while ensuring its photoelectric conversion efficiency. Figure 2 As shown. The method provided by this invention is low-cost, highly compatible with various processes, and suitable for the stabilization of large-area, lead-free perovskite photovoltaic cells.

[0034] The tin-based perovskite solar cells prepared by this invention exhibit low lattice mismatch: because no dopant ions are introduced, defects such as internal stress and dangling bonds caused by ion size mismatch during doping can be effectively prevented, reducing the probability of carrier recombination. This effectively eliminates the existing Sn in perovskite materials. 4+ Because the hydrazine solution is liquid, it can fully wet the perovskite surface, thereby effectively reducing the Sn already formed on the surface of the raw material. 4+ A dense, zero-valent Sn passivation layer can be formed: due to the strong reducing power of hydrazine, Sn can be... 4+ and Sn 2+ The hydrazine solution is reduced to zero valence, and due to the ample contact between the solution and the perovskite surface, a dense and uniform zero-valent Sn film can be formed. This effectively prevents Sn from being reduced to zero valence. 2+ Oxidation: Due to the presence of a dense, uniform Sn protective layer, the internal Sn... 2+ It is difficult for Sn to come into contact with external water and oxygen, thus protecting it. 2+ It is not oxidized, even if Sn is formed. 4+ It will also be reduced to Sn by 0-valent Sn. 2+ This prevents device oxidation and deactivation. It improves the device's photoelectric conversion performance: the excellent conductivity of the dense 0-valent Sn film reduces ohmic voltage drop, thus improving the device's maximum output power and photoelectric conversion efficiency. It offers strong controllability: the thickness of the 0-valent Sn protective layer can be adjusted simply by controlling the hydrazine concentration, the amount added per unit area, and the settling time. The process is simple: it only requires common spin coating, coating, drying, and annealing processes, and has strong compatibility with existing technologies. It is low-cost: using hydrated hydrazine, methylamine, and CaCl2 as raw materials are all common chemical raw materials, without introducing expensive raw materials such as precious metals and ionic liquids, resulting in low production costs. It is beneficial for the production of large-size devices: the method used in this invention is not limited by device size and can be easily extended to the production process of large-size devices, with great industrialization potential. Attached Figure Description

[0035] Figure 1 This is a process flow diagram for preparing tin-based perovskite solar cells according to an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram illustrating the principle of modifying tin-based perovskite solar cells according to the present invention.

[0037] Figure 3 The performance test results of tin-based perovskite solar cells prepared according to embodiments of the present invention before and after modification are shown. Detailed Implementation

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] This invention provides a method for preparing a tin-based perovskite solar cell, comprising:

[0040] An electron transport layer or hole transport layer is formed on the substrate surface;

[0041] A perovskite thin film is formed on the surface of the electron transport layer or hole transport layer;

[0042] A hydrazine-methylamine solution was added dropwise to the surface of the perovskite film for reduction treatment to obtain the reduction product.

[0043] A hole transport layer or an electron transport layer is formed on the surface of the reduction product;

[0044] A current collector is formed on the surface of the hole transport layer or electron transport layer to obtain a tin-based perovskite solar cell.

[0045] The hydrazine-methylamine solution comprises: hydrazine hydrate, CaCl2, and methylamine (MA).

[0046] In this invention, the substrate is preferably a transparent conductive substrate, more preferably selected from ITO (indium tin oxide) or FTO (fluorine-doped SnO2 conductive glass).

[0047] In this invention, the thickness of the substrate is preferably 100-1000 nm, more preferably 200-800 nm, even more preferably 300-600 nm, and most preferably 400-500 nm.

[0048] In this invention, the electron transport layer is preferably formed of an electron transport paste; preferably, the electron transport paste is prepared in a protective atmosphere. In this invention, the method for preparing the electron transport paste preferably includes:

[0049] Electron transport materials are dispersed in a solvent to obtain an electron transport slurry.

[0050] In this invention, the electron transport material is preferably selected from one or more of TiO2, SnO2, and ZnO (or a mixture thereof); the TiO2, SnO2, and ZnO may be pure, doped, or defective; the solvent is preferably selected from any one of DMSO (dimethyl sulfoxide) and DMF (N,N-dimethylformamide) or a mixture thereof; the dispersion method is preferably selected from any one or a combination of ultrasound, oscillation, stirring, and heating.

[0051] In this invention, the method for preparing the electron transport layer preferably includes:

[0052] After coating the substrate surface with an electron transport paste and drying it, an electron transport layer is obtained.

[0053] In this invention, coating is preferably carried out in a protective atmosphere, and the coating method is preferably selected from any one or more combinations of spin coating, spray coating, scraping coating, printing, and immersion methods; the drying method is preferably selected from any one or more combinations of natural air drying, heat drying, forced air drying, and vacuum drying.

[0054] In this invention, the thickness of the electron transport layer is preferably 100nm to 1000nm, more preferably 200 to 800nm, even more preferably 300 to 600nm, and most preferably 400 to 500nm.

[0055] In this invention, the hole transport layer is preferably formed of a hole transport slurry; preferably, the hole transport slurry is prepared in a protective atmosphere. In this invention, the method for preparing the hole transport slurry preferably includes:

[0056] Hole transport material is dispersed in a solvent to obtain a hole transport slurry.

[0057] In this invention, the hole transport material is preferably selected from 2,2',7,7'-tetratetra(N,N-p-methoxyaniline)-9,9'-spirodifluorene (Spiro-OMeTAD), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly(3,4-ethylenedioxythiophene / polystyrene sulfonate (PEDOT:PSS), and nickel oxide (NiO). x The solvent is selected from one or more of copper thiocyanate (CuSCN); the solvent is preferably selected from any one or a mixture of dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF); the dispersion method is preferably selected from any one or a combination of ultrasonication, oscillation, stirring and heating.

[0058] In this invention, the method for preparing the hole transport layer preferably includes:

[0059] After coating the substrate surface with a hole transport slurry and drying it, a hole transport layer is obtained.

[0060] In this invention, coating is preferably carried out in a protective atmosphere, and the coating method is preferably selected from any one or more combinations of spin coating, spray coating, scraping coating, printing, and immersion methods; the drying method is preferably selected from any one or more combinations of natural air drying, heat drying, forced air drying, and vacuum drying.

[0061] In this invention, the thickness of the hole transport layer is preferably 100nm to 1000nm, more preferably 200 to 800nm, even more preferably 300 to 600nm, and most preferably 400 to 500nm.

[0062] In this invention, when the tin-based perovskite solar cell is a cis-cell, an electron transport layer is formed on the substrate surface; when the tin-based perovskite solar cell is an inverted cell, a hole transport layer is formed on the substrate surface.

[0063] In this invention, the perovskite film is preferably formed from a perovskite precursor solution and an antisolvent, more preferably from a tin-based halide perovskite precursor solution. In this invention, the solute in the perovskite precursor solution is preferably ASNX3, wherein A is selected from any one or a mixture of methylamine, formamidinium, Rb, and Cs, and X is selected from one or a mixture of I, Br, and Cl. In this invention, the solvent in the perovskite precursor solution is preferably selected from any one or a mixture of DMSO and DMF. In this invention, the method for preparing the perovskite precursor solution preferably includes:

[0064] The solute is dissolved in a solvent to obtain a perovskite precursor solution.

[0065] In this invention, the dissolution method is preferably selected from any one or more combinations of ultrasound, oscillation, stirring, and heating.

[0066] In this invention, the antisolvent is preferably selected from any one or a mixture of alkanes, haloalkanes, dimethyl ethers, ethylene glycol dimethyl ethers, and dimethyl carbonates.

[0067] In this invention, the method for preparing the perovskite thin film preferably includes:

[0068] A perovskite precursor solution and an antisolvent are sequentially coated onto the surface of the electron transport layer or hole transport layer, followed by drying and annealing to obtain a perovskite thin film.

[0069] In this invention, the coating and drying methods are consistent with those described in the above-mentioned technical solutions, and will not be repeated here. In this invention, the annealing temperature is preferably 100-180°C, more preferably 120-160°C, and most preferably 140°C; the annealing holding time is preferably 1 minute or more, more preferably 15-30 minutes, and most preferably 20-25 minutes.

[0070] In this invention, the thickness of the perovskite thin film is preferably 100-1000 nm, more preferably 200-800 nm, even more preferably 300-600 nm, and most preferably 400-500 nm.

[0071] In this invention, the method for preparing the hydrazine-methylamine solution preferably includes:

[0072] Hydrazine hydrate, CaCl2 and methylamine (MA) are mixed, and the CaCl2 after water absorption is removed to obtain a hydrazine / methylamine solution.

[0073] In this invention, the amount of CaCl2 used is preferably not less than 10 times the mass of hydrazine hydrate, more preferably 15 to 20 times; the amount of methylamine used is preferably not less than 100 times the mass of hydrazine hydrate, more preferably 150 to 200 times.

[0074] In this invention, the mixing method is preferably selected from any one or more combinations of ultrasound, oscillation, stirring, and heating; the method for removing CaCl2 after water absorption is preferably selected from any one or more combinations of natural sedimentation, centrifugation, or filtration.

[0075] In this invention, the reduction process preferably includes:

[0076] A hydrazine-methylamine solution was dropped onto the surface of the perovskite film and allowed to stand to induce hydrazine-Sn reaction. 2+ Sn 4+ The reduction reaction is followed by drying and annealing to remove excess hydrazine and methylamine.

[0077] In this invention, the amount of hydrazine-methylamine solution added is preferably 0.5 to 2 μl per square centimeter of film, more preferably 1 μl per square centimeter of film.

[0078] In this invention, the dripping is preferably performed in a protective atmosphere; the settling time is preferably 1 minute or more, more preferably 15 to 30 minutes, and most preferably 20 to 25 minutes; the annealing temperature is preferably 100 to 180°C, more preferably 120 to 160°C, and most preferably 140°C; the annealing holding time is preferably 1 minute or more, more preferably 15 to 30 minutes, and most preferably 20 to 25 minutes.

[0079] In this invention, the preparation methods of the hole transport layer and the electron transport layer are consistent with those described in the above technical solution, and will not be repeated here. In this invention, when the tin-based perovskite solar cell is a cis-cell, a hole transport layer is formed on the surface of the reduction treatment product; when the tin-based perovskite solar cell is an inverse-cell, a hole transport layer is formed on the surface of the reduction treatment product.

[0080] In this invention, the formation of the current collector is preferably carried out in a protective atmosphere; the current collector is preferably grown on the surface of the hole transport layer or the electron transport layer; the method for growing the current collector is preferably selected from vapor deposition of a conductive layer, bonding of a conductive layer, or coating of a conductive layer; the material of the conductive layer is preferably selected from carbon materials, any metal materials, or any conductive polymer materials.

[0081] In this invention, the thickness of the current collector is preferably 100 nm to 10 μm, more preferably 200 nm to 8 μm, even more preferably 500 nm to 6 μm, even more preferably 1 to 4 μm, and most preferably 2 to 3 μm.

[0082] In an embodiment of the present invention, the flowchart of the fabrication method of the tin-based perovskite solar cell is as follows: Figure 1 As shown, it includes:

[0083] (1) Mix hydrazine hydrate, CaCl2 and methylamine (MA), filter out the water-absorbed CaCl2 to form a hydrazine / methylamine solution;

[0084] (2) Electron transport material slurry, hole transport material slurry, and tin-based halide perovskite precursor solution were prepared in a protective atmosphere;

[0085] (3) Coating an electron transport material or hole transport material slurry onto the surface of a transparent conductive substrate in a protective atmosphere and drying it to form an electron transport layer or hole transport layer; for cis-cells, this step involves coating an electron transport material slurry; for trans-cells, this step involves coating a hole transport material slurry.

[0086] (4) In a protective atmosphere, the perovskite precursor solution and antisolvent are sequentially coated onto the electron transport layer or hole transport layer, and then dried and annealed to form an ASNX3 perovskite film.

[0087] (5) Add hydrazine / methylamine solution dropwise to the surface of the perovskite film under a protective atmosphere and let it stand to induce the reaction of hydrazine with Sn. 2+ Sn 4+ The reduction reaction is followed by drying and annealing to remove excess hydrazine and methylamine.

[0088] (6) Coating a hole transport material or electron transport material slurry onto the surface of the reduced perovskite layer in a protective atmosphere and drying it to form a hole transport or electron transport layer; for cis cells, this step involves coating a hole transport material slurry; for trans cells, this step involves coating an electron transport material slurry.

[0089] (7) Grow a current collector on the hole transport layer or electron transport layer prepared in the previous step in a protective atmosphere.

[0090] This invention utilizes elemental tin, formed in situ on the surface of perovskite materials during hydrazine reduction treatment, as a passivation layer. This avoids the introduction of doping elements, thereby preventing new defects caused by lattice mismatch. Using elemental tin as the passivation layer material provides excellent conductivity, avoiding the problems of poor conductivity and high voltage drop associated with using organic polymers or ionic liquids as passivation layers. Furthermore, using hydrazine solution as a reducing agent allows it to react with the oxidized Sn on the material surface. 4+ Sufficient contact results in a dense and uniform passivation film.

[0091] Example 1

[0092] Perform the following operations sequentially in a protective atmosphere:

[0093] An electron transport layer slurry was prepared by mixing 100 mg of TiO2 (model NR30), 0.4 ml of DMF, and 0.1 ml of DMSO at 55°C for 15 min and then sonicating for 15 min.

[0094] Using NiO x A hole transport layer slurry was prepared by mixing 50 mg of DMF, 0.4 ml of DMF, and 0.1 ml of DMF at 55°C for 15 min and then sonicating for 15 min.

[0095] A perovskite precursor solution was prepared by mixing and stirring 1 mmol (0.1590 g) of methylamine iodide (MAI), 1 mmol (0.3725 g) of stannous iodide (SnI2), 0.8 ml of DMF, and 0.2 ml of DMSO at 55 °C for 45 min and then sonicating for 15 min.

[0096] A hydrazine / CaCl2 / MA solution was obtained by mixing hydrazine hydrate / CaCl2 / MA at a mass ratio of 1:10:100 and sonicating for 30 min, followed by centrifugation to remove CaCl2.

[0097] A bottom electrode precursor solution was prepared by mixing 10 mg of graphene, 0.8 ml of DMF, and 0.2 ml of DMSO at 55 °C for 30 min and then sonicating for 2 hours.

[0098] Electron transport layer slurry, perovskite precursor solution, hydrazine / methylamine solution, hole transport layer slurry, and bottom electrode solution were sequentially added to FTO glass (sheet resistance 10 Ω / sq, transmittance 85%) via spin coating (dropping volume 1 μl / cm for each). 2 Each solution was spin-coated and then annealed at 150°C for 5 minutes.

[0099] A 100nm thick aluminum electrode is deposited on the obtained device to obtain the final battery product.

[0100] Example 2

[0101] Perform the following operations sequentially in a protective atmosphere:

[0102] An electron transport layer slurry was prepared by mixing 50 mg of SnO2 (average particle size 20 nm), 0.4 ml of DMF, and 0.1 ml of DMSO at 55 °C for 15 min and then sonicating for 15 min.

[0103] A hole transport layer slurry was prepared by mixing 50 mg CuSCN, 0.4 ml DMF, and 0.1 ml DMSO at 55°C for 15 min and then sonicating for 15 min.

[0104] A perovskite precursor solution was prepared by mixing and stirring 0.8 mmol (0.1272 g) of methylamine iodide (MAI), 0.2 mmol (0.0344 g) of formamidinium iodide (FAI), 0.95 mmol (0.3539 g) of stannous iodide (SnI2), 0.05 mmol (0.0095 g) of stannous chloride (SnCl2), 0.8 ml of DMF, and 0.2 ml of DMSO at 55 °C for 45 min and then sonicating for 15 min.

[0105] A hydrazine / caCl2 / MA solution was obtained by mixing hydrazine hydrate / CaCl2 / MA at a mass ratio of 1:15:150 and sonicating for 30 min, followed by centrifugation to remove CaCl2.

[0106] A bottom electrode precursor solution was prepared by mixing 10 mg of graphene, 0.8 ml of DMF, and 0.2 ml of DMSO at 55 °C for 30 min and then sonicating for 2 hours.

[0107] Electron transport layer slurry, perovskite precursor solution, hydrazine / methylamine solution, hole transport layer slurry, and bottom electrode solution were sequentially added to FTO glass (sheet resistance 10 Ω / sq, transmittance 85%) via spin coating (dropping volume 1 μl / cm for each). 2 Each solution was spin-coated and then annealed at 150°C for 5 minutes.

[0108] A 100nm thick aluminum electrode is deposited on the obtained device to obtain the final battery product.

[0109] Performance testing

[0110] Referring to the international standard IEC 61215, the IV test method was used to test the performance of the batteries prepared in the examples. The preparation method of the control group was the same as that in Example 1, except that the hydrazine / methylamine solution was not used. The test results are as follows: Figure 3 As shown in the figure, the open-circuit voltage, short-circuit current, and photoelectric conversion efficiency of the battery device were significantly improved after modification with hydrazine / methylamine solution. Specifically, the open-circuit voltage, short-circuit current, and photoelectric conversion efficiency of the control group were 0.926V, 17.4mA / cm², and 0.926V, 17.4mA / cm², respectively. 2 The three indicators of Example 1 were 0.953V and 19.1mA / cm, respectively, representing 11.71% of the total. 2 In Example 1, the percentages were 13.87%, and in Example 2, they were further increased to 0.962V, 19.5%, and 14.97%.

[0111] This invention provides a method for improving the stability of tin-based perovskite solar cells based on hydrazine reduction treatment, using a methylamine solution of hydrazine as a reducing agent to suppress Sn in tin-based perovskite solar cells. 2+ Oxidation and other effects. The reduction treatment method used in this invention has the advantages of low cost, simple process, and good stabilization effect, and is a promising technology for modifying tin-based perovskite solar cells.

[0112] While the invention has been described and illustrated with reference to specific embodiments thereof, such description and illustration are not intended to limit the invention. It will be readily understood by those skilled in the art that various changes may be made to suit particular circumstances, materials, compositions, substances, methods, or processes to the objectives, spirit, and scope of this application without departing from the true spirit and scope of the invention as defined by the appended claims. All such modifications are intended to be within the scope of the appended claims. Although the methods disclosed herein have been described with reference to specific operations performed in a particular order, it should be understood that these operations may be combined, subdivided, or reordered to form equivalent methods without departing from the teachings of the invention. Therefore, unless specifically indicated herein, the order and grouping of operations are not a limitation of this application.

Claims

1. A method for fabricating a tin-based perovskite solar cell, comprising: An electron transport layer or hole transport layer is formed on the substrate surface; A perovskite thin film is formed on the surface of the electron transport layer or hole transport layer; A hydrazine-methylamine solution was added dropwise to the surface of the perovskite film for reduction treatment to obtain the reduction product. The reduction treatment method includes: adding hydrazine-methylamine solution to the surface of the perovskite film, allowing it to stand, drying, and annealing; the standing time is >1 min; the annealing temperature is 100-180℃; and the annealing holding time is >1 min. A hole transport layer or an electron transport layer is formed on the surface of the reduction product; A current collector is formed on the surface of the hole transport layer or electron transport layer to obtain a tin-based perovskite solar cell. The method for preparing the hydrazine-methylamine solution includes: mixing hydrazine hydrate, CaCl2 and methylamine, removing CaCl2 from the resulting mixture to obtain the hydrazine-methylamine solution; wherein the amount of CaCl2 used is not less than 10 times the mass of hydrazine hydrate; and the amount of methylamine used is not less than 100 times the mass of hydrazine hydrate.

2. The method according to claim 1, characterized in that, The mixing method is selected from any one or more combinations of ultrasound, oscillation, stirring, and heating. The method for removing CaCl2 from the resulting mixture is selected from any one or a combination of natural precipitation, centrifugation, or filtration.

3. The method according to claim 1, characterized in that, The drying method is selected from any one or more combinations of natural air drying, heat drying, forced air drying, and vacuum drying.

4. The method according to claim 1, characterized in that, The perovskite film is formed from a perovskite precursor solution and an antisolvent.

5. The method according to claim 4, characterized in that, The solute in the perovskite precursor solution is ASnX3, wherein A is selected from any one or a mixture of methylamine, formamidinium, Rb, and Cs, and X is selected from one or a mixture of I, Br, and Cl. The solvent in the perovskite precursor solution is selected from any one of DMSO, DMF, or a mixture of both. The antisolvent is selected from any one or a mixture of alkanes, halogenated hydrocarbons, dimethyl ether, ethylene glycol dimethyl ether, and dimethyl carbonate.

6. The method according to claim 4, characterized in that, The method for preparing the perovskite thin film includes: A perovskite precursor solution and an antisolvent are sequentially coated on the surface of the electron transport layer or hole transport layer, followed by drying and annealing to obtain a perovskite thin film.

7. The method according to claim 6, characterized in that, The coating method is selected from any one or a combination of spin coating, spray coating, scraping coating, printing, and dipping methods; The drying method is selected from any one or more combinations of natural air drying, heat drying, forced air drying, and vacuum drying. The annealing temperature is 100–180°C; the annealing holding time is >1 min.

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