Thiosulfate-doped low-stress room-temperature flexible perovskite thin film deposition method

Abstract

The invention discloses a thiosulfate-doped low-stress room-temperature flexible perovskite thin film deposition method, and relates to the field of perovskite solar cells, and the method comprises the steps: preparing a perovskite precursor solution; adding iodine as an additive into the perovskite precursor solution to obtain a mixed solution; preparing the mixed solution into a thin film through a spin-coating process, dropwise adding an anti-solvent to the surface of the thin film in the spin-coating process, and standing at normal temperature to form a perovskite thin film; wherein the anti-solvent is a chlorobenzene solution doped with thiosulfate. Controllable heat release is achieved through the oxidation-reduction reaction of thiosulfate and iodine, a traditional thermal annealing process is replaced, precursor solvent volatilization can be promoted, perovskite material crystallization is induced, and the high-quality perovskite thin film can be obtained at the room temperature.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of perovskite solar cells, and particularly relates to a method for depositing a low-stress room-temperature flexible perovskite film doped with thiosulfate. BACKGROUND

[0002] In recent years, organic-inorganic perovskite materials have attracted much attention due to their excellent optical properties (such as high light absorption coefficient, low exciton binding energy, and micron-scale carrier diffusion length), and are considered as one of the strong contenders for the next generation of photovoltaic materials. At the same time, the rapid emergence of emerging application scenarios such as polar exploration, intelligent wearable devices, building photovoltaic integration (BIPV), and vehicle photovoltaic systems (VIPV) has greatly expanded the market size of flexible solar cells, driving the development of solar cell technology towards flexibility and lightness. In particular, as a "soft crystal" material, perovskite material has a low crystallization temperature (≤ 150℃) and a volume modulus to shear modulus ratio of more than 2.0, and can withstand a large degree of compression, deformation, and bending, showing good potential for flexible solar cell preparation. The photoelectric conversion efficiency of the flexible perovskite solar cell (F-PSCs) prepared therefrom has also exceeded 25%. However, this efficiency still lags behind that of rigid perovskite solar cells, and there is still a large room for improvement.

[0003] One of the key factors restricting the performance of flexible perovskite cells is that the traditional perovskite film deposition technology highly depends on a thermal annealing process (usually > 100℃, lasting more than 10 minutes). This process not only may cause the volatilization of organic cations in the perovskite lattice, leading to lattice distortion and residual stress, and thus affecting the crystallization quality and photoelectric performance of the film, but also increases the production cost and process complexity. In addition, the glass transition temperature of flexible substrates (such as PET, PEN, PI, and other polymer materials) is relatively low (about 70℃), and the thermal expansion coefficient is relatively high, which may cause deformation during high-temperature annealing, leading to peeling of the perovskite film from the substrate interface and accumulation of internal stress, further reducing the reliability of the device. Therefore, it is of great significance to develop a room-temperature perovskite film preparation process, which is crucial for avoiding the deformation of flexible substrates, lattice defects, and interface problems caused by high-temperature annealing, reducing the production cost of flexible perovskite solar cells, simplifying the process flow, and accelerating the commercialization process of flexible perovskite solar cells.

[0004] Up to now, the stress regulation technology of room-temperature flexible perovskite thin films is still in the early stage of development, and the mainstream methods mainly include vacuum room-temperature deposition, low-boiling-point solvent annealing method, and component regulation and additive-assisted crystallization. These methods generally focus on relieving the thermal stress caused by the mismatch of the coefficient of thermal expansion (CTE), and have achieved preliminary results in reducing the internal stress of the thin film, improving the crystalline quality and enhancing the stability of the device. However, there are still several key challenges in this field: although the vacuum room-temperature deposition process can achieve low-stress deposition, the complexity and cost of the equipment limit its large-scale application; although the low-boiling-point solvent annealing (such as ether solvent annealing) can effectively release the stress, the crystallization control is difficult, and the quality of the thin film is generally poor, resulting in low device efficiency; although the component regulation and additive-assisted crystallization can synergistically optimize the crystallization and stress state, and significantly improve the stability and performance of the device, its efficiency is still generally lower than that of the traditional thermal annealing device. SUMMARY

[0005] In order to solve the above problems existing in the prior art, the present application provides a low-stress room-temperature flexible perovskite thin film deposition method doped with thiosulfate salt. The technical problem to be solved by the present application is solved by the following technical scheme: The present application provides a low-stress room-temperature flexible perovskite thin film deposition method doped with thiosulfate salt, comprising: Step 1: preparing a perovskite precursor solution; Step 2: adding iodine as an additive to the perovskite precursor solution to obtain a mixed solution; Step 3: preparing the mixed solution into a thin film by a spin coating process, adding an anti-solvent to the surface of the thin film during the spin coating process, and forming a perovskite thin film after standing at room temperature; Wherein, the anti-solvent is a chlorobenzene solution doped with thiosulfate salt.

[0006] The present application provides a perovskite thin film prepared by any one of the embodiments of the low-stress room-temperature flexible perovskite thin film deposition method doped with thiosulfate salt.

[0007] The present application provides a flexible perovskite solar cell, which comprises a PET flexible substrate, a hole transport layer, a perovskite layer, an electron transport layer and a metal electrode layer stacked from bottom to top; wherein the perovskite layer is prepared by any one of the embodiments of the low-stress room-temperature flexible perovskite thin film deposition method doped with thiosulfate salt.

[0008] Compared with the prior art, the present application has the following advantages: 1. The thiosulfate-doped low-stress room-temperature flexible perovskite thin film deposition method of the present application innovatively introduces iodine as an additive in the preparation of a perovskite precursor solution stage, and drops a thiosulfate-doped chlorobenzene solution to the thin film for thin film extraction in the stage of spin coating to form a thin film, realizes controllable exothermic through the redox reaction of thiosulfate and iodine, replaces the traditional thermal annealing process, can promote the volatilization of the precursor solvent, induces perovskite material crystallization, and can obtain high-quality perovskite thin film at room temperature; 2. In the present application, since iodine and thiosulfate are uniformly distributed in the precursor solution and the thin film, the exothermic reaction can be uniformly carried out in the thin film, ensuring that the crystallization process is uniformly heated, and this feature has a significant advantage in uniform film formation in a large area; 3. In the present application, the oxidation-reduction by-product of thiosulfate and iodine, tetrathionate, can form a soluble complex (such as [Pb(S2O3)2] 2+ ) with Pb 2- , effectively reduces the perovskite crystallization activation energy, and further reduces the difficulty of room-temperature perovskite thin film deposition; the active iodine and free cations generated by the reaction can fill the halogen vacancy defects in the perovskite thin film, optimize the carrier transport kinetics, and thus significantly improve the photoelectric performance of the room-temperature flexible perovskite thin film; 4. In the present application, the perovskite thin film crystallization activation energy and crystallization kinetics can be further regulated by thiosulfate cation modulation (such as NH4 + ion), which can improve the photoelectric performance of the room-temperature perovskite thin film; with the help of thiosulfate cation modulation, the perovskite thin film crystallization kinetics regulation and cation vacancy defect passivation can be realized, further optimizing the quality of the room-temperature perovskite thin film.

[0009] The above description is only a summary of the technical solutions of the present application, in order to more clearly understand the technical means of the present application, the content of the specification can be implemented, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following preferred embodiments are described in detail below, and the accompanying drawings are as follows. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a flow chart of a thiosulfate-doped low-stress room-temperature flexible perovskite thin film deposition method provided by an embodiment of the present application; Figure 2 is a process comparison chart of a traditional thin film deposition method and a perovskite thin film deposition method of the present application, wherein (a) is a traditional thin film deposition method, and (b) is a perovskite thin film deposition method of the present application; Figure 3 is a scanning electron microscope image of the perovskite thin film of Example 1 and Comparative Example 1; Figure 4is the X-ray diffraction pattern of the perovskite thin film of Example 1 and Comparative Example 1; Figure 5 is a schematic diagram of a flexible perovskite solar cell provided by an embodiment of the present application; Figure 6 is a J-V curve diagram of the flexible perovskite solar cell prepared based on the perovskite thin film of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0011] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined object, the following will be described in detail in combination with the accompanying drawings and specific embodiments, and a low-stress room-temperature flexible perovskite thin film deposition method doped with thiosulfate salt according to the present application will be described in detail.

[0012] The foregoing and other technical contents, features and effects of the present application will be clearly presented in the following detailed description of specific embodiments in combination with the accompanying drawings. Through the description of the specific embodiments, the technical means and effects adopted by the present application to achieve the predetermined object can be understood more deeply and specifically. However, the accompanying drawings are provided for reference and illustration only, and are not used to limit the technical solutions of the present application.

[0013] In a first aspect, an embodiment of the present application provides a low-stress room-temperature flexible perovskite thin film deposition method doped with thiosulfate salt, please refer to Figure 1 , Figure 1 is a flowchart of a low-stress room-temperature flexible perovskite thin film deposition method doped with thiosulfate salt provided by an embodiment of the present application, as Figure 1 shown, the low-stress room-temperature flexible perovskite thin film deposition method doped with thiosulfate salt of the present embodiment includes the following steps: Step 1: preparing a perovskite precursor solution.

[0014] In an optional embodiment, step 1 includes dissolving metal halide and organic amine salt in a mixed solvent to obtain a perovskite precursor solution.

[0015] Optionally, the mixed solvent is a mixed solvent of 2-methoxyethanol (2-Me) and tetrahydrofuran (THF), and the volume ratio of 2-Me and THF is 7:3-1:1, for example, but not limited to, 7:3, 6:4 or 1:1.

[0016] In the present embodiment, the THF solvent evaporation temperature is 66℃, which is one of the key factors to ensure low-temperature perovskite thin film deposition.

[0017] Optionally, the metal halide includes at least one of lead iodide, lead bromide, lead chloride, cesium iodide, cesium bromide and cesium chloride.

[0018] Optionally, the organic amine salt includes at least one of methylamine iodide, methylamine bromide, methylamine chloride, formamidinium iodide, formamidinium bromide and formamidinium chloride.

[0019] It can be understood that the perovskite precursor solution is formed by dissolving a perovskite material in a solvent, and the perovskite material can be: MA x FA 1-x PbI 3-a Br a , MA x FA 1-x PbI 3-b Cl b , MA x FA 1-x PbBr 3-c Cl c , FA 1-y Cs y PbI3, Cs x FA 1- x PbI 3-a Br a or Cs 1-y (FA x MA 1-x ) y PbI3wherein x and y are each 0-1, and a, b and c are each 0-3. It can be understood that the perovskite material of the present application is not limited to the above compounds, and can also be other perovskite materials considered suitable by those skilled in the art.

[0020] Step 2: iodine is added as an additive to the perovskite precursor solution to obtain a mixed solution.

[0021] Optionally, the concentration of the additive, i.e. iodine, in the mixed solution is 0.05-0.2 mmol / mL, for example, but not limited to, 0.05 mmol / mL, 0.1 mmol / mL, 0.15 mmol / mL or 0.2 mmol / mL.

[0022] In an optional embodiment, step 2 includes: adding iodine to the perovskite precursor solution, stirring to mix evenly in a constant temperature container, and filtering using a PTFE hydrophobic filter membrane to obtain a mixed solution.

[0023] Optionally, the temperature of the constant temperature container is 75°C, the temperature ramp is 1°C, and the stirring time is 12 h.

[0024] Optionally, the pore size of the PTFE hydrophobic filter membrane is 0.45 μm.

[0025] Step 3: the mixed solution is prepared into a thin film by a spin coating process, and a anti-solvent is added dropwise to the surface of the thin film during the spin coating process, and a perovskite thin film is formed after standing at room temperature.

[0026] wherein the anti-solvent is a solution of thiosulfate-doped chlorobenzene.

[0027] Optionally, the thiosulfate includes at least one of sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate, calcium thiosulfate, magnesium thiosulfate, silver thiosulfate, zinc thiosulfate, and barium thiosulfate.

[0028] In an optional embodiment, the concentration of the thiosulfate in the anti-solvent is 0.5-2 mmol / mL, such as but not limited to 0.5 mmol / mL, 1.0 mmol / mL, 1.5 mmol / mL, or 2 mmol / mL.

[0029] In an optional embodiment, step 3 includes: The mixed solution is dropped onto the substrate, which is rotated at a speed of 500-1000 rpm / s for 5-10 seconds, and then rotated at a speed of 3500-5500 rpm / min for 30-55 seconds. At 12-20 seconds before the end of the spin coating, 150-250 μL of the anti-solvent is dropped onto the surface of the thin film. After standing at room temperature, the perovskite thin film is obtained.

[0030] Optionally, the standing time is at least 4 hours.

[0031] The thiosulfate-doped low-stress room-temperature flexible perovskite thin film deposition method of the present application innovatively introduces iodine as an additive in the preparation of the perovskite precursor solution stage, and drops a solution of thiosulfate-doped chlorobenzene onto the thin film to extract the thin film in the stage of spin coating to form a thin film. Through the redox reaction of thiosulfate and iodine, controllable heat release is achieved, which replaces the traditional heat annealing process, promotes the volatilization of the precursor solvent, induces the crystallization of the perovskite material, and obtains a high-quality perovskite thin film at room temperature. In the present application, iodine and thiosulfate are uniformly distributed in the precursor solution and the thin film, and the exothermic reaction can be uniformly carried out in the thin film, ensuring uniform heating during the crystallization process. This feature has a significant advantage in uniform film formation on a large area.

[0032] In the present application, the oxidation-reduction byproduct of thiosulfate and iodine, tetrathionate, can form a soluble complex (such as [Pb(S2O3)2] 2+ ) with Pb 2- , effectively reducing the perovskite crystallization activation energy and further reducing the difficulty of room-temperature perovskite thin film deposition; the active iodine and free cations generated by the reaction can fill the halogen vacancy defects in the perovskite thin film, optimize the carrier transport kinetics, and thus significantly improve the photoelectric performance of the room-temperature flexible perovskite thin film. Through thiosulfate cation modulation (such as NH4 +The sulfite salt can further regulate the crystallization activation energy and crystallization kinetics of the perovskite film, and improve the photoelectric performance of the perovskite film at room temperature; by means of the regulation of sulfite salt cations, the crystallization kinetics regulation and cation vacancy defect passivation of the perovskite film can be realized, and the quality of the perovskite film at room temperature is further optimized.

[0033] In the present application, the sulfur oxides (such as SO4 2- and [Pb(S2O3)2] 2- ) generated by the decomposition of the sulfite salt can be combined with the uncoordinated Pb 2+ on the surface of the perovskite, thereby reducing the surface energy of the film, enhancing the hydrophobicity and long-term stability of the film.

[0034] Further, in combination with the process schematic diagram shown in Figure 2 , the effects of the sulfite salt doped low-stress room temperature flexible perovskite film deposition method of the present application are illustrated by specific examples and comparative examples. Figure 2 is a process comparison diagram of the traditional film deposition method and the perovskite film deposition method of the present application, wherein (a) is the traditional film deposition method, and (b) is the perovskite film deposition method of the present application.

[0035] Example 1 S1: PbI2, FAI and CsI are dissolved in 1 mL of 2-Me / THF mixed solvent with a volume ratio of 7:3 to obtain a perovskite precursor solution; S2: iodine is added as an additive to the perovskite precursor solution, and the mixture is stirred in a constant temperature container at a temperature of 75℃ for 12 hours to obtain a mixed solution; wherein the concentration of the additive in the mixed solution is 0.05 mmol / mL; S3: 75 μL of the mixed solution is drop-coated on the substrate, and then spin coating treatment is performed: first, rotate at a speed of 800 rpm / s for 5 seconds, and then rotate at a speed of 5500 rpm / min for 35 seconds; 200 μL of chlorobenzene anti-solvent doped with sodium sulfite is added to the surface of the film 15 seconds before the end of the spin coating, and the concentration of sodium sulfite in the anti-solvent is 0.5 mmol / mL; then, the film is left to stand at room temperature for 4 hours to obtain a perovskite film.

[0036] It can be understood that sodium sulfite can also be replaced by potassium sulfite, ammonium sulfite, calcium sulfite, magnesium sulfite, silver sulfite, zinc sulfite or barium sulfite.

[0037] Example 2 S1: PbI2, FAI and CsI are dissolved in 1 mL of 2-Me / THF mixed solvent with a volume ratio of 6:4 to obtain a perovskite precursor solution; S2: iodine was added as an additive into the perovskite precursor solution, stirred for 12 h in a constant temperature vessel with a temperature of 75 °C to mix uniformly, filtered using a PTFE hydrophobic filter membrane with a pore size of 0.45 pm to obtain a mixed solution; wherein the concentration of the additive in the mixed solution was 0.1 mmol / mL; S3: 75 pL of the mixed solution was drop-cast on a substrate, followed by spin-coating treatment: first rotated at a speed of 800 rpm / s for 5 s, then rotated at a speed of 5500 rpm / min for 35 s, 200 pL of chlorobenzene anti-solvent doped with sodium thiosulfate was added dropwise to the surface of the thin film 15 s before the end of the spin-coating, the concentration of sodium thiosulfate in the anti-solvent was 1 mmol / mL, then the thin film was left to stand at room temperature for 4 hours to obtain a perovskite thin film.

[0038] It can be understood that sodium thiosulfate can also be replaced by potassium thiosulfate, ammonium thiosulfate, calcium thiosulfate, magnesium thiosulfate, silver thiosulfate, zinc thiosulfate or barium thiosulfate.

[0039] Example 3 S1: PbI2, FAI and CsI were dissolved in 1 mL of 2-Me / THF mixed solvent with a volume ratio of 1:1 to obtain a perovskite precursor solution; S2: iodine was added as an additive into the perovskite precursor solution, stirred for 12 h in a constant temperature vessel with a temperature of 75 °C to mix uniformly, filtered using a PTFE hydrophobic filter membrane with a pore size of 0.45 pm to obtain a mixed solution; wherein the concentration of the additive in the mixed solution was 0.2 mmol / mL; S3: 75 pL of the mixed solution was drop-cast on a substrate, followed by spin-coating treatment: first rotated at a speed of 800 rpm / s for 5 s, then rotated at a speed of 5500 rpm / min for 35 s, 200 pL of chlorobenzene anti-solvent doped with sodium thiosulfate was added dropwise to the surface of the thin film 15 s before the end of the spin-coating, the concentration of sodium thiosulfate in the anti-solvent was 2 mmol / mL, then the thin film was left to stand at room temperature for 4 hours to obtain a perovskite thin film.

[0040] It can be understood that sodium thiosulfate can also be replaced by potassium thiosulfate, ammonium thiosulfate, calcium thiosulfate, magnesium thiosulfate, silver thiosulfate, zinc thiosulfate or barium thiosulfate.

[0041] Comparative Example 1 S1: PbI2, FAI and CsI were dissolved in 1 mL of 2-Me / THF mixed solvent with a volume ratio of 7:3 to obtain a perovskite precursor solution; S2: 75 μL of perovskite precursor solution was dropped on the substrate, followed by spin coating treatment: first spin at 1000 rpm / s for 10 seconds, then spin at 5000 rpm / min for 30 seconds, 200 μL of chlorobenzene was added as anti-solvent to the surface of the film gradually and continuously 8 seconds before the end of the spin coating. Then, the film was quickly transferred to a hot plate at 100℃ for 30 min annealing treatment, and perovskite film was obtained.

[0042] See Figure 3 , Figure 3 is the scanning electron microscope image of the perovskite film of Example 1 and Comparative Example 1. Apparently, the perovskite film prepared by Example 1 has a larger and more uniform grain size, showing better morphology characteristics, compared with Comparative Example 1.

[0043] See Figure 4 , Figure 4 is the X-ray diffraction pattern of the perovskite film of Example 1 and Comparative Example 1. The (100) crystal plane diffraction peak of the perovskite film prepared by Example 1 is stronger, indicating higher film crystallinity, compared with Comparative Example 1.

[0044] In the second aspect, the present application provides a perovskite film prepared by the low-stress room temperature flexible perovskite film deposition method with thiosulfate doping provided in the first aspect.

[0045] For specific contents and corresponding beneficial effects of the perovskite film, please refer to the related contents of the low-stress room temperature flexible perovskite film deposition method with thiosulfate doping provided in the first aspect, which will not be repeated here.

[0046] In the third aspect, the present application provides a flexible perovskite solar cell, please see Figure 5 , Figure 5 is a schematic diagram of a flexible perovskite solar cell provided by an embodiment of the present application, as shown in Figure 5 , the flexible perovskite solar cell comprises a PET flexible substrate, a hole transport layer, a perovskite layer, an electron transport layer and a metal electrode layer arranged from bottom to top; wherein the perovskite layer is prepared by the low-stress room temperature flexible perovskite film deposition method with thiosulfate doping provided in the first aspect.

[0047] For example, with sodium thiosulfate, the process of preparing a perovskite cell device with the structure of PET / NiO X / Me-4PACz / / Cs 0.06 FA 0.94 PbI3 / PC 61 BM / Ag is as follows: (1) The treatment method of PET flexible substrate: First, the etched PET flexible substrate (10 ohm / square, 100 nm) was cleaned by isopropyl alcohol with a lint-free cloth to remove surface dust particles, and then cleaned by nitrogen gun. Subsequently, the flexible substrate was cleaned by deionized water, acetone and isopropyl alcohol in an ultrasonic cleaning tank in sequence and stored in an alcohol solution.

[0048] (2) Preparation method of hole transport layer: After the substrate was taken out and dried by nitrogen, it was dried at 120°C for 20 minutes and treated by ultraviolet ozone for 30 minutes to remove organic contaminants and increase its surface hydrophilicity. Subsequently, 100 μL of Me-4PACz: anhydrous ethanol (0.335 mg / mL) mixed solution was spin-coated at a speed of 3000 rpm / min for 30 seconds, and then dried at 100°C for 10 minutes and treated by ultraviolet ozone for 30 minutes again. It was placed for standby use.

[0049] (3) Preparation method of perovskite precursor solution: The preparation method of the perovskite precursor solution comprises: dissolving 691.50 mg of PbI2, 227.00 mg of FAI and 21.04 mg of CsI in 1 mL of 2-Me / THF mixed solvent with a volume ratio of 7:3, adding iodine with a concentration of 0.05 mmol / mL as an additive, stirring in a constant temperature container at a temperature of 75°C for 12 hours to mix uniformly, and filtering to obtain a perovskite precursor solution added with iodine using a PTFE hydrophobic filter membrane with a pore size of 0.45 μm.

[0050] (4) Preparation method of perovskite thin film: 75 μL of the perovskite precursor solution added with iodine was delivered to the surface of the flexible substrate covered with the hole transport layer, and then spin-coating treatment was performed: first, spin at a speed of 800 rpm / s for 5 seconds, and then spin at a speed of 5500 rpm / min for 35 seconds. At 15 seconds before the end of spin-coating, 200 μL of chlorobenzene / sodium thiosulfate was added to the surface of the thin film as an anti-solvent. Subsequently, the thin film was placed at room temperature for 4 hours.

[0051] (5) Preparation method of electron transport layer and silver electrode: After the room temperature perovskite thin film deposition was completed, the treated thin film was arranged in a customized mask, and 20 nm of PCBM electron transport layer was evaporated at a rate of 0.5 Å / s under vacuum conditions, followed by evaporation of a silver electrode with a thickness of 100 nm. 61

[0052] See Figure 6 , Figure 6 ​is a J-V curve diagram of the flexible perovskite solar cell prepared based on the perovskite thin film of Example 1 and Comparative Example 1. Apparently, the perovskite solar cell prepared by Example 1 has higher photoelectric conversion efficiency, especially the short-circuit current and fill factor are obviously improved, relative to Comparative Example 1.

[0053] In the present application, thiosulfate is used as a key raw material, which greatly reduces the material cost of room-temperature flexible perovskite thin film deposition. The exothermic reaction is realized in situ by redox reaction, completely eliminating the traditional high-temperature annealing process, and reducing energy consumption by more than 80%. At the same time, the reaction byproduct can automatically passivate the film defects, simplifying the post-processing procedure. Under the condition of compatible continuous production process, the production efficiency of the corresponding flexible perovskite solar cell is expected to be increased by more than 3 times, and the comprehensive production cost can be reduced by more than 60%, which has a broad application market.

[0054] It should be noted that, in this document, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. The terms "connected" and "coupled" as well as "linking" or "communicating" are not restricted to direct connections or coupling but also include indirect connections or coupling.

[0055] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific feature or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific feature or characteristic described can be combined in an appropriate manner in any one or more embodiments or examples. In addition, a person skilled in the art can combine and integrate different embodiments or examples described in the present specification.

[0056] The above is further detailed description of the present application in combination with specific preferred embodiments, and cannot be deemed as limitation of the specific implementation of the present application to these descriptions. For those skilled in the art to which the present application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, and all of them shall be deemed as falling within the protection scope of the present application.

Claims

1. A method for depositing low-stress, room-temperature flexible perovskite thin films doped with thiosulfate, characterized in that, include: Step 1: Prepare perovskite precursor solution; Step 2: Iodine is added as an additive to the perovskite precursor solution to obtain a mixed solution; Step 3: The mixed solution is prepared into a thin film by spin coating. During the spin coating process, an anti-solvent is dropped onto the surface of the thin film, and after standing at room temperature, a perovskite thin film is formed. The antisolvent is a chlorobenzene solution doped with thiosulfate.

2. The method for deposition of low-stress room-temperature flexible perovskite thin films doped with thiosulfate according to claim 1, characterized in that, Step 1 includes: The perovskite precursor solution is obtained by dissolving a metal halide and an organic amine salt in a mixed solvent; wherein the mixed solvent is a mixture of 2-methoxyethanol and tetrahydrofuran in a volume ratio of 7:3 to 1:

1.

3. The method for deposition of low-stress room-temperature flexible perovskite thin films doped with thiosulfate according to claim 2, characterized in that, The metal halide includes at least one of lead iodide, lead bromide, cesium iodide, cesium bromide, and cesium chloride.

4. The method for deposition of low-stress room-temperature flexible perovskite thin films doped with thiosulfate according to claim 2, characterized in that, The organic amine salt includes at least one of iodomethylamine, bromomethylamine, chloromethylamine, iodomethylammonium, bromomethylammonium, and chloromethylammonium.

5. The method for deposition of low-stress room-temperature flexible perovskite thin films doped with thiosulfate according to claim 1, characterized in that, The concentration of the additive in the mixed solution is 0.05-0.2 mmol / mL.

6. The method for deposition of low-stress room-temperature flexible perovskite thin films doped with thiosulfate according to claim 1, characterized in that, The thiosulfate includes at least one of sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate, calcium thiosulfate, magnesium thiosulfate, silver thiosulfate, zinc thiosulfate, and barium thiosulfate.

7. The method for deposition of low-stress room-temperature flexible perovskite thin films doped with thiosulfate according to claim 1, characterized in that, The concentration of thiosulfate in the antisolvent is 0.5-2 mmol / mL.

8. The method for deposition of low-stress room-temperature flexible perovskite thin films doped with thiosulfate according to claim 1, characterized in that, Step 3 includes: The mixed solution is dropped onto the substrate and rotated at a speed of 500-1000 rpm / s for 5-10 seconds, then rotated at a speed of 3500-5500 rpm / min for 30-55 seconds. 12-20 seconds before the end of spin coating, 150-250 μL of antisolvent is dropped onto the film surface. After standing at room temperature, the perovskite film is obtained.

9. A perovskite thin film, characterized in that, It was prepared by the low-stress room-temperature flexible perovskite thin film deposition method with thiosulfate doping as described in any one of claims 1-8.

10. A flexible perovskite solar cell, characterized in that, The flexible perovskite solar cell comprises, from bottom to top, a PET flexible substrate, a hole transport layer, a perovskite layer, an electron transport layer, and a metal electrode layer; wherein, the perovskite layer is prepared by the low-stress room-temperature flexible perovskite thin film deposition method doped with thiosulfate as described in any one of claims 1-8.

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