Flexible perovskite battery and preparation method thereof

Abstract

The invention provides a flexible perovskite cell and a preparation method thereof, and belongs to the technical field of solar cells, and the preparation method comprises the following steps: mixing thermoplastic polyurethane with 3-isocyanate propyl triethoxy silane, adding anhydrous N, N-dimethylformamide, and heating to prepare a modified polyurethane solution; mixing formamidine hydriodate, iodized salt, methyl ammonium salt, the modified polyurethane solution and 4-hydrazinobenzene sulfonic acid, adding a DMSO / DMF solvent, and stirring to prepare a perovskite precursor solution; the PET / ITO substrate is used as a bottom electrode layer; spin-coating an isolation layer on the bottom electrode layer; spin-coating a SnO2 precursor solution on the isolation layer to prepare an electron transport layer; spin-coating a perovskite precursor solution on the electron transport layer to prepare a perovskite layer; spin-coating a hole transport layer mixed solution on the perovskite layer to prepare a hole transport layer; and evaporating a top electrode layer on the hole transport layer to prepare the flexible perovskite cell. The perovskite cell prepared by the invention has good flexibility and tensile property, and meanwhile, the water and oxygen resistance is improved.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, specifically to a flexible perovskite solar cell and its preparation method. Background Technology

[0002] Perovskite solar cells have become a research hotspot in next-generation photovoltaic technology due to their advantages such as wide availability of raw materials, low manufacturing costs, and flexible processing conditions. Flexible perovskite solar cells, in particular, with their thin, light, and bendable properties, show broad application prospects in wearable electronics, building-integrated photovoltaics, and portable energy devices.

[0003] However, flexible perovskite solar cells still face several technical challenges in transitioning from laboratory research to industrial application. First, perovskite materials themselves exhibit intrinsic instability; their crystal lattices are riddled with ion vacancy defects, which are easily induced by external electric fields, light, and thermal stress, leading to phase separation and performance degradation. Simultaneously, metal ions (such as Pb) in perovskites... 2+ It is easily oxidized, which accelerates the decomposition of materials and further reduces the operational stability of the device.

[0004] Secondly, flexible applications place higher demands on the mechanical durability of devices. As a polycrystalline semiconductor material, perovskite thin films often have weak points in their grain boundaries, which are prone to forming and propagating microcracks during repeated bending or stretching, leading to a rapid decline in device performance. Therefore, how to endow perovskite layers with better flexibility and mechanical stability has become a key research focus. Furthermore, flexible batteries typically use polymer-based substrates such as PET / ITO, but these substrates have limited barrier properties against water and oxygen. Water and oxygen in the environment can easily penetrate the perovskite layer, inducing material decomposition and severely affecting the electrical performance and lifespan of the device.

[0005] In summary, there is a need to provide a flexible perovskite solar cell and its preparation method to solve the problems existing in the prior art. Summary of the Invention

[0006] In view of this, the present invention provides a flexible perovskite solar cell and a method for preparing the same, so as to improve the flexibility and tensile properties of the perovskite thin film and at the same time solve the performance degradation problem caused by water and oxygen permeation.

[0007] To achieve the above objectives, the present invention provides a flexible perovskite solar cell and a method for preparing the same, comprising the following steps: S1. A modified polyurethane solution is prepared by mixing thermoplastic polyurethane with 3-isocyanate-propyltriethoxysilane, adding anhydrous N,N-dimethylformamide, heating and stirring. A modified polyurethane solution is prepared by mixing formamidinium hydroiodate, iodide, methylammonium salt, modified polyurethane solution and 4-hydrazinobenzenesulfonic acid, adding DMSO / DMF solvent and stirring. S2. Clean and activate the PET / ITO substrate to obtain the bottom electrode layer; add SnO2 precursor solution dropwise for spin coating, heat, cool, and activate to obtain the electron transport layer. S3. Drop the perovskite precursor solution onto the electron transport layer, spin-coat, heat, and cool to obtain the perovskite layer. S4. Drop the hole transport layer mixture onto the perovskite layer, spin-coat, and dry to obtain the hole transport layer; deposit the top electrode layer on the hole transport layer to prepare a flexible perovskite solar cell.

[0008] This invention introduces isocyanate-propyltriethoxysilane (IPTS) into thermoplastic polyurethane (TPU), enabling the TPU molecular chain to possess both a flexible backbone and reactive polar groups. The isocyanate groups (-NCO) at the ends of the IPTS molecules exhibit high reactivity, reacting with the amino groups (-NH2) in the TPU segments to form a stable urea bond structure (-NH-CO-NH-). This urea bond not only enhances the association ability between polymer segments but also reacts with free iodide ions (I-) in the crystal lattice. - This process forms stable ion-dipole interactions, anchoring iodide ions during perovskite layer formation and preventing abnormal iodide ion accumulation, thereby improving the structural stability of flexible perovskite solar cells. Simultaneously, under external stretching or repeated bending, urea bonds play a crucial role in stress dispersion and buffering between the flexible backbone chains. The amide groups in its molecular structure gradually release and absorb mechanical energy during loading-unloading cycles, effectively alleviating stress at grain boundaries, delaying crack propagation, and thus improving the flexibility and tensile properties of perovskite solar cells.

[0009] In addition, the flexible intrinsic structure of the TPU main chain can endow the perovskite layer with good bendability, so that it can still maintain its structural integrity under bending external force, avoiding breakage or delamination, thereby improving the overall flexibility of the battery.

[0010] Building upon this, the present invention further introduces 4-hydrazinobenzenesulfonic acid molecules into the perovskite precursor solution, whose sulfonic acid group (-SO3H) can react with uncoordinated lead ions (Pb) in the perovskite lattice. 2+The formation of SO-Pb bonds effectively passivates grain boundaries and surface defects. The reducing properties of the hydrazine group suppress the oxidation process of lead ions, enhancing the intrinsic stability of the perovskite layer. Simultaneously, 4-hydrazinobenzenesulfonic acid promotes the formation of larger and more uniform grain structures in the perovskite layer, improving its electron transport efficiency. Furthermore, it synergistically modifies polyurethane to construct a rigid grain-flexible interface structure. When the flexible perovskite solar cell is subjected to external forces, this structure can counteract the forces through minute reversible deformation, further enhancing the flexibility of the flexible perovskite solar cell.

[0011] The bottom electrode layer in this invention uses a flexible PET / ITO substrate, which provides the bendability of the perovskite solar cell base while enabling the collection and transport of photogenerated electrons; the electron transport layer can extract electrons and block hole migration, improving charge separation efficiency; the hole transport layer is used to transport holes and block electron backflow, so that charge carriers can be effectively separated and output; the top electrode layer, as the back electrode, is responsible for collecting holes and conducting current, while also providing encapsulation and protection for the device.

[0012] Optionally, an isolation layer is spin-coated between the bottom electrode layer and the electron transport layer. The isolation solution of the isolation layer is prepared by activating polyvinylcarbazole, adding octadecyltrichlorosilane and anhydrous toluene, stirring at 500-600 rpm for 2-4 hours, reacting at a constant temperature of 50-60°C for 20-30 minutes, and then cooling.

[0013] Optionally, the insulating layer is prepared by dripping an insulating liquid into the center of the bottom electrode layer, rotating it at 1000-1500 rpm for 10-15 seconds, then spin-coating it at 3000-3500 rpm for 30-40 seconds, heating it at 95-105°C for 10-15 minutes, and then cooling it.

[0014] This invention introduces hydroxyl-active sites into polyvinylcarbazole (PVK) through UV-ozone treatment, causing it to undergo a condensation reaction with the silane end groups (-SiCl3) of octadecyltrichlorosilane (OTS) to form an isolation layer containing Si-OC bonds. In this isolation layer, the dense coverage of PVK effectively fills the microporous defects at the PET / ITO interface, providing a stable matrix for the ordered arrangement of OTS. OTS, on the other hand, is firmly anchored to the PVK film through covalent bonds, with its long-chain alkyl groups oriented outwards, further reducing the free volume of the film and imparting strong hydrophobicity. The chemical bonds formed between PVK and OTS at the interface and their synergistic effect not only avoid the problem of insufficient hydrophobicity of PVK but also suppress the film discontinuity caused by OTS hydrolysis, improving the device's barrier ability against external water and oxygen, thereby enhancing the long-term environmental stability of the flexible perovskite solar cell. Simultaneously, as a semiconductor polymer, PVK allows for efficient electron transport, ensuring the photoelectric conversion efficiency of the flexible perovskite solar cell.

[0015] Optionally, in step S1, after adding anhydrous N,N-dimethylformamide, the mixture is heated at 60-80°C for 1-2 hours and stirred at 800-900 rpm for 6-8 hours to obtain a modified polyurethane solution; the iodide salt includes lead iodide and cesium iodide, and the methylammonium salt includes methylammonium bromide and methylammonium chloride; after adding DMSO / DMF solvent, the mixture is stirred for 1-2 hours to obtain a perovskite precursor solution.

[0016] Optionally, in step S2, the bottom electrode layer is prepared by ultrasonically cleaning the PET / ITO substrate with anhydrous ethanol and deionized water for 30-50 minutes, drying it at 80-90°C, fixing it on a glass plate, and irradiating it in an ultraviolet-ozone cleaner for 20-30 minutes; the electron transport layer is prepared by adding a SnO2 precursor solution to the center of the bottom electrode layer, spin-coating it at 4000-4500 rpm for 20-40 seconds, heating it at 80-95°C for 30-40 minutes, cooling it to room temperature, and irradiating it in an ultraviolet-ozone cleaner for 40-50 minutes.

[0017] In this invention, ultrasonic cleaning and ultraviolet-ozone treatment of the PET / ITO substrate effectively remove surface impurities, improving the cleanliness and uniformity of the bottom electrode layer and providing a good adhesion interface for subsequent thin film deposition. The electron transport layer, achieved through a combination of thermal treatment and ultraviolet-ozone treatment, forms a dense and uniform transport layer structure, enhancing carrier transport efficiency.

[0018] Optionally, in step S3, the perovskite layer is prepared by dropping a perovskite precursor solution onto the center of the electron transport layer, first spin-coating at 900-1100 rpm for 10-15 s, then spin-coating at 4200-4600 rpm for 20-30 s, dropping chlorobenzene onto the center of the electron transport layer, spin-coating for 10-20 s, heating at 110-120℃ for 10-20 min, and cooling to room temperature.

[0019] In this invention, the crystal quality and light absorption capacity of the film are improved by combining two-stage spin coating with chlorobenzene-induced crystallization, and the defect density is reduced, which is beneficial to improving the photoelectric conversion efficiency.

[0020] Optionally, in step S4, the hole transport layer is prepared by adding a hole transport layer mixture to the center of the perovskite layer, spin-coating at 3500~3800 rpm for 25~30s, and drying at 30~40℃ for 24~30h; the top electrode layer is prepared by placing a glass plate in a vacuum evaporation coating equipment, first depositing a 10~15nm thick gold foil at a speed of 0.2~0.4nm / s, and then depositing a 70~80nm thick gold foil at a speed of 2~5nm / s.

[0021] Optionally, the flexible perovskite solar cell includes a bottom electrode layer, an electron transport layer, a perovskite layer, a hole transport layer and a top electrode layer stacked sequentially, wherein the bottom electrode layer is made of a PET / ITO substrate and the top electrode layer is made of metal vapor deposition. The perovskite layer comprises the following raw materials in parts by weight: 85.5-87 parts of formamidinium hydroiodate, 250-280 parts of lead iodide, 10-11.5 parts of cesium iodide, 1.5-2 parts of methylammonium bromide, 6-8 parts of methylammonium chloride, 35-38 parts of modified polyurethane solution, and 0.8-1.2 parts of 4-hydrazinobenzenesulfonic acid; the modified polyurethane solution comprises the following raw materials in parts by weight: 18-24 parts of thermoplastic polyurethane, 2-4 parts of 3-isocyanate-propyltriethoxysilane, and 1400-1500 parts of anhydrous N,N-dimethylformamide.

[0022] Optionally, an isolation layer is spin-coated between the bottom electrode layer and the electron transport layer. The isolation layer comprises the following raw materials in parts by weight: 10-12 parts of polyvinylcarbazole, 4-6 parts of octadecyltrichlorosilane, and 860-880 parts of anhydrous toluene.

[0023] Optionally, the electron transport layer comprises the following raw materials in parts by weight: 10-20 parts of 15wt% SnO2 colloidal dispersion and 30-60 parts of ultrapure water; The hole transport layer comprises the following raw materials in parts by weight: 70-75 parts Spiro-OMeTAD powder, 1100-1200 parts chlorobenzene, 26-30 parts tributyl phosphate, 8-10 parts 520 g / L TFSI-Li solution, and 3-5 parts 400 g / L FK209-Co(Ⅲ)-TFSI solution.

[0024] It should be understood that the flexible perovskite solar cell prepared in this invention is a thin-film solar cell.

[0025] The above-described technical solution of the present invention has at least the following beneficial effects: This invention introduces isocyanate-based propyltriethoxysilane (IPTS) into thermoplastic polyurethane (TPU) to construct urea bond structures within the TPU chain. This anchors free iodide ions in the perovskite, preventing iodide ion migration and abnormal enrichment, thus improving the structural stability of the battery. The urea bond structure can disperse stress, mitigate crack propagation, and improve the flexibility and tensile properties of flexible perovskite solar cells. The flexible nature of the TPU main chain endows the light-absorbing layer with good bendability, preventing breakage or delamination and enhancing overall flexibility and stability.

[0026] This invention also introduces 4-hydrazinobenzenesulfonic acid molecules into the perovskite precursor solution, utilizing its sulfonic acid groups to form "SO-Pb" bonds with lead ions to achieve passivation of grain boundaries and surface defects; simultaneously, the hydrazino group inhibits lead oxidation, improving material stability. 4-hydrazinobenzenesulfonic acid can promote grain growth and uniform distribution, and synergistically with modified polyurethane to construct a "rigid grain-flexible interface" structure, further enhancing the flexibility of flexible perovskite solar cells. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the flexible perovskite solar cell in an embodiment of the present invention; Figure 2 This is a SEM image of the perovskite layer in Example 1 of the present invention; Figure 3 This is a SEM image of the perovskite layer in Comparative Example 3 of the present invention.

[0028] In the picture: 1. Bottom electrode layer; 2. Isolation layer; 3. Electron transport layer; 4. Perovskite layer; 5. Hole transport layer; 6. Top electrode layer. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0030] Preparation: Select a 750mm×750mm PET / ITO film as the substrate. Clean the PET / ITO substrate with anhydrous ethanol and deionized water for 30 minutes each to remove impurities from the surface of the PET / ITO substrate. Dry it at 80℃ and use polyimide (PI) tape to stick and fix it to a glass plate. Place it in an ultraviolet-ozone cleaner for 30 minutes to obtain the bottom electrode layer.

[0031] Example 1 10g of polyvinylcarbazole was irradiated in a UV-ozone cleaner for 30 minutes. Then, 4g of octadecyltrichlorosilane and 860g of anhydrous toluene were added. The mixture was sealed and stirred at 600rpm for 2 hours under N2 protection. The mixture was then heated to 50°C and reacted for 20 minutes. After cooling to room temperature, the isolation solution was obtained.

[0032] 10g of 15wt% SnO2 colloidal dispersion and 30g of ultrapure water were mixed and stirred with a magnetic stirrer for 1.5h to obtain SnO2 precursor solution.

[0033] 18g of thermoplastic polyurethane (TPU) was mixed with 2g of 3-isocyanate-propyltriethoxysilane, and 1400g of anhydrous N,N-dimethylformamide (DMF) was added. The mixture was heated at 60°C for 1.5h and stirred at 800rpm for 7h to obtain a modified polyurethane solution.

[0034] 85.5 g formamidinium hydroiodate (FAI), 250 g lead iodide (PbI2), 10 g cesium iodide (CsI), 1.5 g methyl ammonium bromide (MABr), 6 g methyl ammonium chloride (MACl), 35 g modified polyurethane solution, and 0.8 g 4-hydrazinobenzenesulfonic acid were mixed and stirred. Then, 500 mL of DMSO / DMF solvent with a volume ratio of 1:4 was added, and the mixture was stirred for 1 h until the solution became clear, thus obtaining the perovskite precursor solution.

[0035] 70g Spiro-OMeTAD powder, 1100g chlorobenzene, 26g tributyl phosphate (T-BP), 8g TFSI-Li solution with a concentration of 520g / L, and 3g FK209-Co(Ⅲ)-TFSI solution with a concentration of 400g / L were mixed and stirred evenly to obtain a hole transport layer mixture.

[0036] Fix the glass plate onto the spin coater suction cup, drop 100 μL of isolation liquid onto the bottom electrode layer, spin coat at 1000 rpm for 12 s, then spin coat at 3000 rpm for 35 s, place the sample on a 95°C heating stage for 15 min, and cool to room temperature to form the isolation layer.

[0037] The glass plate was fixed onto the suction cup of the spin coater, and 150 mL of SnO2 precursor solution was dropped into the center of the isolation layer. The spin coater was started and the plate was spin-coated at 4000 rpm for 25 seconds. The plate was then heated on an 80°C heating stage for 40 minutes, then cooled to room temperature and irradiated in an ultraviolet-ozone cleaner for 40 minutes to obtain the electron transport layer.

[0038] Fix the glass plate onto the suction cup of the spin coater, drop 60 mL of perovskite precursor solution onto the center of the electron transport layer, spin coat at 1000 rpm for 12 s, then spin coat at 4200 rpm for 30 s, drop 140 mL of chlorobenzene onto the center of the electron transport layer and spin coat for another 10 s. After spin coating is complete, place the glass plate on a heating stage at 110 ℃ for 15 min, then remove the sample from the heating stage and cool it to room temperature to obtain the perovskite layer.

[0039] The glass plate was fixed onto the suction cup of the spin coater, and 60 mL of hole transport layer mixture was dropped onto the center of the perovskite layer. The mixture was spin-coated at 3600 rpm for 25 seconds and then dried in a drying oven at 40°C for 24 hours to obtain the hole transport layer.

[0040] The glass plate is placed in the evaporation chamber of the vacuum evaporation coating equipment. First, a 15 nm thick gold foil is deposited at a speed of 0.2 nm / s. Then, the evaporation rate is slowly increased to 3 nm / s and maintained at a uniform speed to deposit a 90 nm thick gold foil to obtain the top electrode layer and prepare a flexible perovskite solar cell.

[0041] Example 2 11g of polyvinylcarbazole was irradiated in a UV-ozone cleaner for 30 minutes. Then, 5g of octadecyltrichlorosilane and 870g of anhydrous toluene were added. The mixture was sealed and stirred at 550 rpm for 3 hours under N2 protection. The mixture was then heated to 55°C and reacted for 30 minutes. After cooling to room temperature, the isolation solution was obtained.

[0042] 15g of 15wt% SnO2 colloidal dispersion and 45g of ultrapure water were mixed and stirred with a magnetic stirrer for 2 hours to obtain a SnO2 precursor solution.

[0043] 20g of thermoplastic polyurethane (TPU) was mixed with 3g of 3-isocyanate-propyltriethoxysilane, and 1450g of anhydrous N,N-dimethylformamide (DMF) was added. The mixture was heated at 80°C for 1.5h and stirred at 800rpm for 6h to obtain a modified polyurethane solution.

[0044] 86.5 g formamidinium hydroiodate (FAI), 260 g lead iodide (PbI2), 11 g cesium iodide (CsI), 1.8 g methyl ammonium bromide (MABr), 7 g methyl ammonium chloride (MACl), 36 g modified polyurethane solution, and 1 g 4-hydrazinobenzenesulfonic acid were mixed and stirred. Then, 500 mL of DMSO / DMF solvent with a volume ratio of 1:4 was added, and the mixture was stirred for 2 h until the solution became clear, thus obtaining the perovskite precursor solution.

[0045] 73g Spiro-OMeTAD powder, 1150g chlorobenzene, 28g tributyl phosphate (T-BP), 9g TFSI-Li solution with a concentration of 520g / L, and 4g FK209-Co(Ⅲ)-TFSI solution with a concentration of 400g / L were mixed and stirred evenly to obtain a hole transport layer mixture.

[0046] Fix the glass plate onto the spin coater suction cup, drop 100 μL of isolation liquid onto the bottom electrode layer, spin coat at 1100 rpm for 12 s, then spin coat at 3500 rpm for 30 s, place the sample on a heating stage at 105 ℃ for 10 min, and cool to room temperature to form the isolation layer.

[0047] The glass plate was fixed onto the suction cup of the spin coater, and 150 mL of SnO2 precursor solution was dropped into the center of the isolation layer. The spin coater was started and the plate was spin-coated at 4000 rpm for 30 seconds. The plate was then heated on an 80°C heating stage for 40 minutes, then cooled to room temperature and irradiated in an ultraviolet-ozone cleaner for 50 minutes to obtain the electron transport layer.

[0048] Fix the glass plate onto the suction cup of the spin coater, drop 60 mL of perovskite precursor solution onto the center of the electron transport layer, spin coat at 1100 rpm for 10 s, then spin coat at 4400 rpm for 25 s, drop 140 mL of chlorobenzene onto the center of the electron transport layer and spin coat for another 15 s. After spin coating is complete, place the glass plate on a heating stage at 120°C and heat for 15 min. Remove the sample from the heating stage and cool it to room temperature to obtain the perovskite layer.

[0049] The glass plate was fixed onto the suction cup of the spin coater, and 60 mL of hole transport layer mixture was dropped onto the center of the perovskite layer. The mixture was spin-coated at 3800 rpm for 25 seconds and then dried in a drying oven at 40°C for 26 hours to obtain the hole transport layer.

[0050] The glass plate is placed in the evaporation chamber of the vacuum evaporation coating equipment. First, a 12nm thick gold foil is deposited at a speed of 0.4nm / s. Then, the evaporation rate is slowly increased to 4nm / s and maintained at a uniform speed to deposit an 80nm thick gold foil to obtain the top electrode layer and prepare a flexible perovskite solar cell.

[0051] Example 3 12g of polyvinylcarbazole was irradiated in a UV-ozone cleaner for 25 minutes. Then, 6g of octadecyltrichlorosilane and 880g of anhydrous toluene were added. The mixture was sealed and stirred at 600rpm for 4 hours under N2 protection. The mixture was then heated to 60°C and reacted for 25 minutes. After cooling to room temperature, the isolation solution was obtained.

[0052] 20g of 15wt% SnO2 colloidal dispersion and 60g of ultrapure water were mixed and stirred with a magnetic stirrer for 2h to obtain SnO2 precursor solution.

[0053] 24g of thermoplastic polyurethane (TPU) was mixed with 4g of 3-isocyanate-propyltriethoxysilane, and 1500g of anhydrous N,N-dimethylformamide (DMF) was added. The mixture was heated at 70°C for 2 hours and stirred at 800 rpm for 8 hours to obtain a modified polyurethane solution.

[0054] 87g formamidinium hydroiodate (FAI), 280g lead iodide (PbI2), 11.5g cesium iodide (CsI), 2g methylammonium bromide (MABr), 8g methylammonium chloride (MACl), 38g modified polyurethane solution, and 1.2g 4-hydrazinobenzenesulfonic acid were mixed and stirred. Then, 500mL of DMSO / DMF solvent with a volume ratio of 1:4 was added, and the mixture was stirred for 1.5h until the solution became clear, thus obtaining the perovskite precursor solution.

[0055] 75g Spiro-OMeTAD powder, 1200g chlorobenzene, 29g tributyl phosphate (T-BP), 10g TFSI-Li solution with a concentration of 520g / L, and 5g FK209-Co(Ⅲ)-TFSI solution with a concentration of 400g / L were mixed and stirred evenly to obtain a hole transport layer mixture.

[0056] Fix the glass plate onto the spin coater suction cup, drop 100 μL of isolation liquid onto the bottom electrode layer, spin coat at 1500 rpm for 14 s, then spin coat at 3500 rpm for 30 s, place the sample on a 95°C heating stage and heat for 15 min, then cool to room temperature to form the isolation layer.

[0057] The glass plate was fixed onto the suction cup of the spin coater, and 150 mL of SnO2 precursor solution was dropped into the center of the isolation layer. The spin coater was started and the plate was spin-coated at 4000 rpm for 35 seconds. The plate was then heated on a 95°C heating stage for 35 minutes, then cooled to room temperature and irradiated in an ultraviolet-ozone cleaner for 45 minutes to obtain the electron transport layer.

[0058] Fix the glass plate onto the suction cup of the spin coater, drop 60 mL of perovskite precursor solution onto the center of the electron transport layer, spin coat at 1000 rpm for 12 s, then spin coat at 4400 rpm for 25 s, drop 140 mL of chlorobenzene onto the center of the electron transport layer and spin coat for another 20 s. After spin coating is complete, place the glass plate on a heating stage at 110 ℃ and heat for 10 min. Remove the sample from the heating stage and cool it to room temperature to obtain the perovskite layer.

[0059] The glass plate was fixed onto the suction cup of the spin coater, and 60 mL of hole transport layer mixture was dropped onto the center of the perovskite layer. The mixture was spin-coated at 3600 rpm for 25 seconds and then dried in a drying oven at 30°C for 30 hours to obtain the hole transport layer.

[0060] The glass plate is placed in the evaporation chamber of the vacuum evaporation coating equipment. First, a 12nm thick gold foil is deposited at a speed of 0.4nm / s. Then, the evaporation rate is slowly increased to 4nm / s and maintained at a uniform speed to deposit an 80nm thick gold foil to obtain the top electrode layer and prepare a flexible perovskite solar cell.

[0061] Example 4 10g of 15wt% SnO2 colloidal dispersion and 30g of ultrapure water were mixed and stirred with a magnetic stirrer for 1.5h to obtain SnO2 precursor solution.

[0062] 18g of thermoplastic polyurethane (TPU) was mixed with 2g of 3-isocyanate-propyltriethoxysilane, and 1400g of anhydrous N,N-dimethylformamide (DMF) was added. The mixture was heated at 60°C for 1.5h and stirred at 800rpm for 7h to obtain a modified polyurethane solution.

[0063] 85.5 g formamidinium hydroiodate (FAI), 250 g lead iodide (PbI2), 10 g cesium iodide (CsI), 1.5 g methyl ammonium bromide (MABr), 6 g methyl ammonium chloride (MACl), 35 g modified polyurethane solution, and 0.8 g 4-hydrazinobenzenesulfonic acid were mixed and stirred. Then, 500 mL of DMSO / DMF solvent with a volume ratio of 1:4 was added, and the mixture was stirred for 1 h until the solution became clear, thus obtaining the perovskite precursor solution.

[0064] 70g Spiro-OMeTAD powder, 1100g chlorobenzene, 26g tributyl phosphate (T-BP), 8g TFSI-Li solution with a concentration of 520g / L, and 3g FK209-Co(Ⅲ)-TFSI solution with a concentration of 400g / L were mixed and stirred evenly to obtain a hole transport layer mixture.

[0065] The glass plate was fixed onto the suction cup of the spin coater. 150 mL of SnO2 precursor solution was dropped into the center of the bottom electrode layer. The spin coater was started and the plate was spin-coated at 4000 rpm for 25 s. The plate was then heated on an 80°C heating stage for 40 min. After cooling to room temperature, the plate was irradiated in an ultraviolet-ozone cleaner for 40 min to obtain the electron transport layer.

[0066] Fix the glass plate onto the suction cup of the spin coater, drop 60 mL of perovskite precursor solution onto the center of the electron transport layer, spin coat at 1000 rpm for 12 s, then spin coat at 4200 rpm for 30 s, drop 140 mL of chlorobenzene onto the center of the electron transport layer and spin coat for another 10 s. After spin coating is complete, place the glass plate on a heating stage at 110 ℃ and heat for 15 min. Remove the sample from the heating stage and cool it to room temperature to obtain the perovskite layer.

[0067] The glass plate was fixed onto the suction cup of the spin coater, and 60 mL of hole transport layer mixture was dropped onto the center of the perovskite layer. The mixture was spin-coated at 3600 rpm for 25 seconds and then dried in a drying oven at 40°C for 24 hours to obtain the hole transport layer.

[0068] The glass plate is placed in the evaporation chamber of the vacuum evaporation coating equipment. First, a 15 nm thick gold foil is deposited at a speed of 0.2 nm / s. Then, the evaporation rate is slowly increased to 3 nm / s and maintained at a uniform speed to deposit a 90 nm thick gold foil to obtain the top electrode layer and prepare a flexible perovskite solar cell.

[0069] Example 5 15g of 15wt% SnO2 colloidal dispersion and 45g of ultrapure water were mixed and stirred with a magnetic stirrer for 2 hours to obtain a SnO2 precursor solution.

[0070] 20g of thermoplastic polyurethane (TPU) was mixed with 3g of 3-isocyanate-propyltriethoxysilane, and 1450g of anhydrous N,N-dimethylformamide (DMF) was added. The mixture was heated at 80°C for 1.5h and stirred at 800rpm for 6h to obtain a modified polyurethane solution.

[0071] 86.5 g formamidinium hydroiodate (FAI), 260 g lead iodide (PbI2), 11 g cesium iodide (CsI), 1.8 g methyl ammonium bromide (MABr), 7 g methyl ammonium chloride (MACl), 36 g modified polyurethane solution, and 1 g 4-hydrazinobenzenesulfonic acid were mixed and stirred. Then, 500 mL of DMSO / DMF solvent with a volume ratio of 1:4 was added, and the mixture was stirred for 2 h until the solution became clear, thus obtaining the perovskite precursor solution.

[0072] 73g Spiro-OMeTAD powder, 1150g chlorobenzene, 28g tributyl phosphate (T-BP), 9g TFSI-Li solution with a concentration of 520g / L, and 4g FK209-Co(Ⅲ)-TFSI solution with a concentration of 400g / L were mixed and stirred evenly to obtain a hole transport layer mixture.

[0073] The glass plate was fixed onto the suction cup of the spin coater. 150 mL of SnO2 precursor solution was dropped into the center of the bottom electrode layer. The spin coater was started and the plate was spin-coated at 4000 rpm for 30 seconds. The plate was then heated on an 80°C heating stage for 40 minutes. After cooling to room temperature, the plate was irradiated in an ultraviolet-ozone cleaner for 50 minutes to obtain the electron transport layer.

[0074] Fix the glass plate onto the suction cup of the spin coater, drop 60 mL of perovskite precursor solution onto the center of the electron transport layer, spin coat at 1100 rpm for 10 s, then spin coat at 4400 rpm for 25 s, drop 140 mL of chlorobenzene onto the center of the electron transport layer and spin coat for another 15 s. After spin coating is complete, place the glass plate on a heating stage at 120°C and heat for 15 min. Remove the sample from the heating stage and cool it to room temperature to obtain the perovskite layer.

[0075] The glass plate was fixed onto the suction cup of the spin coater, and 60 mL of hole transport layer mixture was dropped onto the center of the perovskite layer. The mixture was spin-coated at 3800 rpm for 25 seconds and then dried in a drying oven at 40°C for 26 hours to obtain the hole transport layer.

[0076] The glass plate is placed in the evaporation chamber of the vacuum evaporation coating equipment. First, a 12nm thick gold foil is deposited at a speed of 0.4nm / s. Then, the evaporation rate is slowly increased to 4nm / s and maintained at a uniform speed to deposit an 80nm thick gold foil to obtain the top electrode layer and prepare a flexible perovskite solar cell.

[0077] Example 6 20g of 15wt% SnO2 colloidal dispersion and 60g of ultrapure water were mixed and stirred with a magnetic stirrer for 2h to obtain SnO2 precursor solution.

[0078] 24g of thermoplastic polyurethane (TPU) was mixed with 4g of 3-isocyanate-propyltriethoxysilane, and 1500g of anhydrous N,N-dimethylformamide (DMF) was added. The mixture was heated at 70°C for 2 hours and stirred at 800 rpm for 8 hours to obtain a modified polyurethane solution.

[0079] 87g formamidinium hydroiodate (FAI), 280g lead iodide (PbI2), 11.5g cesium iodide (CsI), 2g methylammonium bromide (MABr), 8g methylammonium chloride (MACl), 38g modified polyurethane solution, and 1.2g 4-hydrazinobenzenesulfonic acid were mixed and stirred. Then, 500mL of DMSO / DMF solvent with a volume ratio of 1:4 was added, and the mixture was stirred for 1.5h until the solution became clear, thus obtaining the perovskite precursor solution.

[0080] 75g Spiro-OMeTAD powder, 1200g chlorobenzene, 29g tributyl phosphate (T-BP), 10g TFSI-Li solution with a concentration of 520g / L, and 5g FK209-Co(Ⅲ)-TFSI solution with a concentration of 400g / L were mixed and stirred evenly to obtain a hole transport layer mixture.

[0081] The glass plate was fixed onto the suction cup of the spin coater. 150 mL of SnO2 precursor solution was dropped into the center of the bottom electrode layer. The spin coater was started and the plate was spin-coated at 4000 rpm for 35 s. The plate was then heated on a 95°C heating stage for 35 min. After cooling to room temperature, the plate was irradiated in an ultraviolet-ozone cleaner for 45 min to obtain the electron transport layer.

[0082] Fix the glass plate onto the suction cup of the spin coater, drop 60 mL of perovskite precursor solution onto the center of the electron transport layer, spin coat at 1000 rpm for 12 s, then spin coat at 4400 rpm for 25 s, drop 140 mL of chlorobenzene onto the center of the electron transport layer and spin coat for another 20 s. After spin coating is complete, place the glass plate on a heating stage at 110 ℃ and heat for 10 min. Remove the sample from the heating stage and cool it to room temperature to obtain the perovskite layer.

[0083] The glass plate was fixed onto the suction cup of the spin coater, and 60 mL of hole transport layer mixture was dropped onto the center of the perovskite layer. The mixture was spin-coated at 3600 rpm for 25 seconds and then dried in a drying oven at 30°C for 30 hours to obtain the hole transport layer.

[0084] The glass plate is placed in the evaporation chamber of the vacuum evaporation coating equipment. First, a 12nm thick gold foil is deposited at a speed of 0.4nm / s. Then, the evaporation rate is slowly increased to 4nm / s and maintained at a uniform speed to deposit an 80nm thick gold foil to obtain the top electrode layer and prepare a flexible perovskite solar cell.

[0085] The present invention also includes comparative examples and related experiments.

[0086] Comparative Example 1 The only difference from Example 4 is that no modified polyurethane solution was added to the perovskite precursor solution. All other components and preparation steps are exactly the same, and a flexible perovskite battery is obtained.

[0087] Comparative Example 2 The only difference from Example 5 is that 3-isocyanate-propyltriethoxysilane was not added to the modified polyurethane solution. All other components and preparation steps were exactly the same, and a flexible perovskite battery was obtained.

[0088] Comparative Example 3 The only difference from Example 1 is that 4-hydrazinobenzenesulfonic acid was not added to the perovskite precursor solution. All other components and preparation steps were exactly the same, and a flexible perovskite battery was obtained.

[0089] The performance of the flexible perovskite solar cells prepared in Examples 1-6 and Comparative Examples 1-3 was tested. The basic photoelectric conversion efficiency (PCE0) of the flexible perovskite solar cells was tested according to the standard DB35T 2143-2023 "Test Procedure for Conversion Efficiency of Perovskite Solar Cells". The flexibility test method for flexible perovskite solar cells: The flexible perovskite solar cell is bent into an arc with a radius of 100 mm and repeatedly cyclically bent 5000 times. Then, the photoelectric conversion efficiency (PCE1) of the flexible perovskite solar cell is tested.

[0090] Test method for mechanical tensile properties of flexible perovskite solar cells: Stretch the flexible perovskite solar cell by 15%, remove the tension to allow the flexible perovskite solar cell to automatically recover, and then test the photoelectric conversion efficiency PCE2 of the flexible perovskite solar cell.

[0091] Test method for water and oxygen resistance of flexible perovskite solar cells: After placing the flexible perovskite solar cells in an environment with a temperature of 25℃ and a relative humidity of 50% for 800 hours, the photoelectric conversion efficiency (PCE3) of the flexible perovskite solar cells is tested.

[0092] The relevant performance test results are shown in Table 1.

[0093] Table 1

[0094] In Table 1, the formula for calculating the retention rate of flexible perovskite solar cells is: η i =PCE i / PCE0×100, where i=1, 2, 3.

[0095] like Figure 1 As shown, the flexible perovskite solar cells prepared in Examples 1-3 include a bottom electrode layer 1, an isolation layer 2, an electron transport layer 3, a perovskite layer 4, a hole transport layer 5, and a top electrode layer 6 stacked sequentially.

[0096] As shown in Table 1, compared with Examples 4-6 without the introduction of the isolation layer, Examples 1-3 have higher resistance to water and oxygen after the introduction of the isolation layer. This indicates that the isolation layer helps to block the corrosion of flexible perovskite solar cells by water and oxygen, thereby improving the service life of flexible perovskite solar cells.

[0097] As can be seen from Table 1, compared with Example 4, Comparative Example 1 lacks a flexible buffer structure in the perovskite layer due to the absence of a modified polyurethane solution, which leads to increased grain boundary stress and lower overall flexibility and tensile properties than Example 4.

[0098] As shown in Table 1, compared with Example 5, the polyurethane solution used in Comparative Example 2 was not modified, resulting in a decrease in both its flexibility and tensile strength. The decrease in tensile strength retention was more significant, indicating that unmodified polyurethane is difficult to form an effective buffer structure in the film, and the structural stability is weakened.

[0099] Figure 2 This is a SEM image of the perovskite layer in Example 1 of the present invention, in which the grain size is relatively large and the grain distribution is uniform. Figure 3The image shown is a SEM image of the perovskite layer in Comparative Example 3 of this invention, in which the grain size is small and the grain distribution is uneven. As can be seen from Table 1, compared to Example 1, Comparative Example 3 did not introduce 4-hydrazinobenzenesulfonic acid into the perovskite precursor solution, resulting in a smaller grain size and uneven grain distribution in the perovskite layer, which easily leads to stress concentration and reduces the flexibility and tensile strength of the perovskite layer.

[0100] The above are preferred embodiments of the present invention. Those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a flexible perovskite solar cell, characterized in that, Includes the following steps: S1. A modified polyurethane solution is prepared by mixing thermoplastic polyurethane with 3-isocyanate-propyltriethoxysilane, adding anhydrous N,N-dimethylformamide, heating and stirring. A modified polyurethane solution is prepared by mixing formamidinium hydroiodate, iodide, methylammonium salt, modified polyurethane solution and 4-hydrazinobenzenesulfonic acid, adding DMSO / DMF solvent and stirring. S2. Clean and activate the PET / ITO substrate to obtain the bottom electrode layer; add SnO2 precursor solution dropwise for spin coating, heat, cool, and activate to obtain the electron transport layer. S3. Drop the perovskite precursor solution onto the electron transport layer, spin-coat, heat, and cool to obtain the perovskite layer. S4. Drop the hole transport layer mixture onto the perovskite layer, spin-coat, and dry to obtain the hole transport layer. Flexible perovskite solar cells were fabricated by depositing a top electrode layer on the hole transport layer.

2. The method for preparing a flexible perovskite solar cell according to claim 1, characterized in that, An isolation layer is also spin-coated between the bottom electrode layer and the electron transport layer. The isolation solution of the isolation layer is prepared by activating polyvinylcarbazole, adding octadecyltrichlorosilane and anhydrous toluene, stirring at 500-600 rpm for 2-4 hours, reacting at 50-60°C for 20-30 minutes, and then cooling.

3. The method for preparing a flexible perovskite solar cell according to claim 2, characterized in that, The insulating layer is prepared by dripping an insulating liquid into the center of the bottom electrode layer, rotating it at 1000-1500 rpm for 10-15 seconds, then spin-coating it at 3000-3500 rpm for 30-40 seconds, heating it at 95-105°C for 10-15 minutes, and then cooling it.

4. The method for preparing a flexible perovskite solar cell according to claim 1, characterized in that, In step S1, after adding anhydrous N,N-dimethylformamide, the mixture is heated at 60-80°C for 1-2 hours and stirred at 800-900 rpm for 6-8 hours to obtain a modified polyurethane solution. The iodide salts include lead iodide and cesium iodide, and the methylammonium salts include methylammonium bromide and methylammonium chloride; After adding DMSO / DMF solvent, stir for 1-2 hours to obtain a perovskite precursor solution.

5. The method for preparing a flexible perovskite solar cell according to claim 1, characterized in that, In step S2, the bottom electrode layer is prepared by ultrasonically cleaning the PET / ITO substrate with anhydrous ethanol and deionized water for 30-50 minutes, drying it at 80-90°C, fixing it on a glass plate, and irradiating it in an ultraviolet-ozone cleaner for 20-30 minutes. The electron transport layer is prepared by adding a SnO2 precursor solution to the center of the bottom electrode layer, spin-coating at 4000-4500 rpm for 20-40 seconds, heating at 80-95°C for 30-40 minutes, cooling to room temperature, and irradiating with an ultraviolet-ozone cleaner for 40-50 minutes.

6. The method for preparing a flexible perovskite solar cell according to claim 1, characterized in that, In step S3, the perovskite layer is prepared by dropping a perovskite precursor solution onto the center of the electron transport layer, first spin-coating at 900-1100 rpm for 10-15 s, then spin-coating at 4200-4600 rpm for 20-30 s, dropping chlorobenzene onto the center of the electron transport layer, spin-coating for 10-20 s, heating at 110-120℃ for 10-20 min, and cooling to room temperature.

7. The method for preparing a flexible perovskite solar cell according to claim 1, characterized in that, In step S4, the hole transport layer is obtained by adding a hole transport layer mixture to the center of the perovskite layer, spin-coating at 3500~3800 rpm for 25~30s, and drying at 30~40℃ for 24~30h. The top electrode layer is prepared by placing a glass plate in a vacuum evaporation coating equipment, first depositing a 10-15 nm thick gold foil at a speed of 0.2-0.4 nm / s, and then depositing a 70-90 nm thick gold foil at a speed of 2-5 nm / s.

8. A flexible perovskite solar cell, prepared by the method for preparing a flexible perovskite solar cell according to claim 1, characterized in that, It includes a bottom electrode layer, an electron transport layer, a perovskite layer, a hole transport layer and a top electrode layer stacked sequentially, wherein the bottom electrode layer is made of a PET / ITO substrate and the top electrode layer is made of metal vapor deposition; The perovskite layer comprises the following raw materials in parts by weight: 85.5-87 parts of formamidinium hydroiodate, 250-280 parts of lead iodide, 10-11.5 parts of cesium iodide, 1.5-2 parts of methylammonium bromide, 6-8 parts of methylammonium chloride, 35-38 parts of modified polyurethane solution, and 0.8-1.2 parts of 4-hydrazinobenzenesulfonic acid; the modified polyurethane solution comprises the following raw materials in parts by weight: 18-24 parts of thermoplastic polyurethane, 2-4 parts of 3-isocyanate-propyltriethoxysilane, and 1400-1500 parts of anhydrous N,N-dimethylformamide.

9. A flexible perovskite solar cell according to claim 8, characterized in that, An isolation layer is also spin-coated between the bottom electrode layer and the electron transport layer. The isolation layer comprises the following raw materials in parts by weight: 10-12 parts of polyvinylcarbazole, 4-6 parts of octadecyltrichlorosilane, and 860-880 parts of anhydrous toluene.

10. A flexible perovskite solar cell according to claim 8, characterized in that, The electron transport layer comprises the following raw materials in parts by weight: 10-20 parts of 15wt% SnO2 colloidal dispersion and 30-60 parts of ultrapure water; The hole transport layer comprises the following raw materials in parts by weight: 70-75 parts Spiro-OMeTAD powder, 1100-1200 parts chlorobenzene, 26-30 parts tributyl phosphate, 8-10 parts 520 g / L TFSI-Li solution, and 3-5 parts 400 g / L FK209-Co(Ⅲ)-TFSI solution.

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