Solvent composition, perovskite thin film and method for preparing the same, solar cell

Abstract

The application relates to the technical field of photovoltaic cells, in particular to a solvent composition, a perovskite thin film and a preparation method thereof and a solar cell. The solvent composition comprises: a main solvent with a boiling point greater than 150 DEG C, the main solvent being selected from at least one of a perfluoroalkane compound and a perfluoro tertiary amine compound; an extraction solvent with a boiling point greater than 150 DEG C, the extraction solvent being selected from at least one of an aromatic ether compound, a halogenated aromatic hydrocarbon compound and an ester compound; and an adjusting solvent with a polarity between the polarities of the main solvent and the extraction solvent. The solvent composition provided by the application realizes mild and controllable extraction through the synergistic effect of the main solvent, the extraction solvent and the adjusting solvent, improves the crystallization quality of the thin film, the temperature of solvent bath annealing treatment can reach above the conversion temperature of the photoactive phase of the perovskite thin film, the phase transition is sufficient, and the photoelectric performance of the device is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic cells, in particular to a solvent composition, a perovskite thin film and a preparation method thereof, and a solar cell. BACKGROUND

[0002] Perovskite solar cells have attracted extensive attention due to their long carrier diffusion length, high light absorption coefficient, adjustable band gap, compatibility with various preparation methods, and simple preparation method.

[0003] In the preparation of the perovskite thin film of the perovskite solar cell, thermal annealing is a key process. The traditional thermal annealing process has poor temperature uniformity, and there is thermal delay and temperature gap, which affects the film layer quality of the perovskite thin film. Immersing the perovskite wet film in a perovskite anti-solvent for solvent bath annealing can improve heat transfer and promote crystallization of the perovskite.

[0004] In the conventional technology, solvent bath annealing often uses a single perovskite anti-solvent for extraction.

[0005] For single-component solvent bath annealing, using a solvent with high polarity is beneficial to improve the extraction effect, fully extract the residual solvent (such as DMF, DMSO, NMP, etc.) in the precursor, and improve the lifetime of the perovskite thin film under light and heat conditions. However, using a solvent with high polarity may have the risk of dissolving the surface components of the perovskite or re-proportioning the surface components of the perovskite, resulting in undesirable morphology and surface defects (such as incomplete crystal growth, fine crystal grains, etc.), which is not conducive to the transport of carriers. In addition, most anti-solvents have low boiling points (such as chlorobenzene, toluene, etc.), making it difficult for the perovskite thin film to reach the conversion temperature of the photoactive phase (usually 120℃-150℃), which affects the photoelectric conversion performance of the device. SUMMARY

[0006] Therefore, it is necessary to provide a solvent composition, a perovskite thin film and a preparation method thereof, and a solar cell, to realize mild and controllable extraction, improve the crystallization quality of the perovskite thin film, and enable the temperature of the solvent bath annealing treatment to reach above the conversion temperature of the photoactive phase of the perovskite thin film, so that the phase transition is sufficient, and the photoelectric performance of the device can be improved.

[0007] In a first aspect, the present application provides a solvent composition, which comprises a main solvent, an extraction solvent and an adjusting solvent. The boiling point of the main solvent is greater than 150℃, and the main solvent is selected from at least one of perfluoroalkane compounds and perfluoro tertiary amine compounds. The boiling point of the extraction solvent is greater than 150℃, and the extraction solvent is selected from at least one of aromatic ether compounds, halogenated aromatic compounds and ester compounds. The polarity of the adjusting solvent is between the polarity of the main solvent and the polarity of the extraction solvent.

[0008] In some embodiments, the volume ratio of the bulk solvent, the extraction solvent and the adjusting solvent is (5-8):(0.5-2):(1-3).

[0009] Further, the volume ratio of the bulk solvent, the extraction solvent and the adjusting solvent is (7-8):(1-2):(1-2).

[0010] In some embodiments, the bulk solvent is selected from at least one of perfluorododecane, perfluorotridecane, perfluorotetradecane, perfluoropentadecane, perfluorohexadecane, perfluorotributylamine, perfluorotripentylamine and perfluorotrihexylamine.

[0011] In some embodiments, the extraction solvent is selected from at least one of anisole, o-methylanisole, m-methylanisole, p-methylanisole, phenetole, methyl phenetole, 4-methyl phenetole, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, butyl butyrate, ethyl hexanoate, ethyl heptanoate, ethyl octanoate, hexyl acetate, heptyl acetate, pentyl propionate, hexyl butyrate, isobutyl isovalerate, butyl isovalerate, butyl valerate, isopentyl isobutyrate, isopentyl butyrate, pentyl butyrate, isopentyl isovalerate and methyl benzoate.

[0012] In some embodiments, the adjusting solvent is selected from at least one of octane, perfluoro-octane, decane, perfluoro-toluene and perfluoro-biphenyl.

[0013] In some embodiments, the bulk solvent has a boiling point less than or equal to 250°C.

[0014] In some embodiments, the extraction solvent has a boiling point less than or equal to 250°C.

[0015] In a second aspect of the present application, a preparation method of a perovskite thin film is provided, which comprises the following steps: immersing a perovskite wet film into the solvent composition provided in the first aspect, and performing a solvent bath annealing treatment to form a perovskite thin film.

[0016] In some embodiments, the temperature of the solvent bath annealing treatment is greater than or equal to the conversion temperature of the photoactive phase of the perovskite thin film.

[0017] In some embodiments, the temperature of the solvent bath annealing treatment is 120-150°C.

[0018] In some embodiments, after the solvent bath annealing treatment, the preparation method further comprises the following step: performing a heat treatment on the perovskite thin film formed by the solvent bath annealing treatment, and the temperature of the heat treatment is lower than the temperature of the solvent bath annealing treatment.

[0019] In a third aspect of the present application, a perovskite thin film is provided, which is prepared by the preparation method of the perovskite thin film provided in the second aspect.

[0020] In a fourth aspect, the present application provides a solar cell comprising the perovskite film according to the third aspect.

[0021] Compared with the prior art, the present application has at least the following beneficial effects: the solvent composition provided by some embodiments of the present application has a main solvent as a main component, which has relatively low polarity and hardly extracts the perovskite precursor solvent, and provides a relatively high boiling point and thermal field for the solvent bath composition, and the abundant fluorine substituents on the molecule endow it with high hydrophobicity, which can isolate the perovskite from water vapor in the air during the solvent bath process, reduce the generation of high-density defect states of the perovskite caused by excessive humidity during the annealing process, and thus improve the humidity tolerance of the preparation environment and reduce the operating cost of maintaining a low-humidity environment; the polarity of the extraction solvent is relatively higher than that of the main solvent, which is used to extract the perovskite precursor solvent; the polarity of the adjusting solvent is between that of the main solvent and the extraction solvent, which can adjust the extraction of the perovskite precursor solvent in the perovskite wet film by the solvent composition.

[0022] Further, the main solvent, the extraction solvent and the adjusting solvent have a synergistic effect. The boiling points of the main solvent and the extraction solvent are both greater than 150℃, which jointly adjust the azeotropic point of the solvent composition, so that the temperature of the solvent bath annealing process can be higher than the conversion temperature of the photoactive phase of the perovskite film, and the solvent composition is not rapidly volatilized and consumed; the adjusting solvent not only has an extraction adjusting effect, but also can buffer the polarity difference between the main solvent and the extraction solvent, which is conducive to better mutual solubility of the three and avoids stratification. Thus, the main solvent, the extraction solvent and the adjusting solvent adjust the polarity of the solvent composition and control the interaction between the solvent composition and the perovskite precursor solvent, so that the extraction effect, the boiling point and the damage to the perovskite components are balanced. Compared with a single anti-solvent, the physical parameters of the solvent composition provided by the present application can be adjusted, and the process window is wider.

[0023] In summary, the solvent composition provided by some embodiments of the present application realizes a mild and controllable extraction through the synergistic effect of the main solvent, the extraction solvent and the adjusting solvent, improves the crystallization quality of the perovskite film, makes the temperature of the solvent bath annealing process higher than the conversion temperature of the photoactive phase of the perovskite film, fully converts the phase, and thus improves the photoelectric performance of the device, while reducing the process cost, widening the process window and facilitating large-scale industrial application. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to better describe and illustrate the embodiments or examples provided by the present application, one or more drawings can be referred to. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any one of the disclosed applications, the presently described embodiments or examples, and the best mode presently understood of these applications. Moreover, in all the drawings, the same reference numerals represent the same components.

[0025] Figure 1 A schematic diagram of a method for preparing a perovskite film in an embodiment of the present application.

[0026] Figure 2 A SEM test diagram of a perovskite film in Example 1 of the present application.

[0027] Figure 3 A SEM test diagram of a perovskite film in Example 2 of the present application.

[0028] Figure 4 A SEM test diagram of a perovskite film in Comparative Example 1 of the present application.

[0029] Figure 5 A SEM test diagram of a perovskite film in Comparative Example 2 of the present application.

[0030] Figure 6 A J-V test curve of a solar cell in Example 1 and Comparative Examples 1-4 of the present application.

[0031] Figure 7 An XRD test diagram of a perovskite film in Example 1 and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0032] Reference will now be made in detail to embodiments of the present application, one or more examples of which are described herein. Each example is provided as an explanation and not as a limitation of the present application. Indeed, it will be apparent to one of ordinary skill in the art that numerous modifications and variations of the present application are possible in light of the above teachings. For example, features described or illustrated as part of one embodiment can be used with another embodiment to yield a still further embodiment.

[0033] Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents. Other objects, features, and aspects of the present application are disclosed in or are apparent from the following detailed description of the application. It is to be understood by the foregoing description that the form of the application herein disclosed is to be considered only as an example and not a limitation of the application. The application is intended to cover all alternatives, modifications, and equivalents falling within the scope of the claims.

[0034] In the present application, the technical features described in an open form include both the closed technical solution consisting of the listed features and the open technical solution containing the listed features.

[0035] In the present application, if no special description, the numerical interval is considered to be continuous, and includes the minimum value and maximum value of the range, and every value between the minimum value and maximum value. Further, when the range refers to an integer, every integer between the minimum value and maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0036] If no special description, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0037] If no special description, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0038] If no special description, all steps of the present application can be performed in sequence, or randomly, preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, it is mentioned that the method can further comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0039] If no special description, the "including" and "containing" mentioned in the present application means open, and can also be closed. For example, the "including" and "containing" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0040] In the first aspect of the present application, a solvent composition is provided, which comprises a main solvent, an extraction solvent and an adjusting solvent. The boiling point of the main solvent is greater than 150℃, and the main solvent is selected from at least one of perfluoroalkane compounds and perfluoro tertiary amine compounds. The boiling point of the extraction solvent is greater than 150℃, and the extraction solvent is selected from at least one of aromatic ether compounds, halogenated aromatic compounds and ester compounds. The polarity of the adjusting solvent is between the polarity of the main solvent and the polarity of the extraction solvent.

[0041] The solvent composition provided by some embodiments of the present application has a main solvent as a main component, which has relatively low polarity and hardly extracts the perovskite precursor solvent, provides a high boiling point and a high-temperature field for the solvent bath composition, and has a high hydrophobicity due to the rich fluorine substituents on the molecules, which can isolate the perovskite from water vapor in the air during the solvent bath process, reduce the generation of high-density defect states of the perovskite caused by excessive humidity during the annealing process, thereby improving the humidity tolerance of the preparation environment and reducing the operating cost of maintaining a low-humidity environment; the polarity of the extraction solvent is relatively higher than that of the main solvent, which is used to extract the perovskite precursor solvent; the polarity of the adjusting solvent is between that of the main solvent and the extraction solvent, which can adjust the extraction of the perovskite precursor solvent in the wet perovskite film by the solvent composition.

[0042] Further, the main solvent, the extraction solvent and the adjusting solvent have a synergistic effect. The boiling points of the main solvent and the extraction solvent are both greater than 150°C, which jointly adjust the azeotropic point of the solvent composition, so that the temperature of the solvent bath annealing process can be higher than the conversion temperature of the photoactive phase of the perovskite film, and the solvent composition is not rapidly volatilized and consumed; the adjusting solvent not only has an extraction adjusting effect, but also can buffer the polarity difference between the main solvent and the extraction solvent, which is conducive to better mutual solubility of the three and avoids stratification. Therefore, the main solvent, the extraction solvent and the adjusting solvent adjust the polarity of the solvent composition and control the interaction between the solvent composition and the perovskite precursor solvent, so that the extraction effect, the boiling point and the damage to the perovskite composition are balanced. Compared with a single anti-solvent, the physical parameters of the solvent composition provided by the present application can be adjusted, and the process window is wider.

[0043] In summary, the solvent composition provided by some embodiments of the present application realizes a mild and controllable extraction through the synergistic effect of the main solvent, the extraction solvent and the adjusting solvent, improves the crystallization quality of the perovskite film, makes the temperature of the solvent bath annealing process higher than the conversion temperature of the photoactive phase of the perovskite film, fully converts the phase, and further improves the photoelectric performance of the device. At the same time, the process cost is reduced, the process window is widened, and the large-scale industrial application is facilitated.

[0044] In some embodiments, the volume ratio of the bulk solvent, the extraction solvent, and the adjusting solvent is (5-8):(0.5-2):(1-3). For example, the volume ratio of the bulk solvent, the extraction solvent, and the adjusting solvent can be, but is not limited to, 5:2:3, 6:2:2, 6:1:3, 7:0.5:2.5, 7:1:2, 7:2:1, 8:0.5:1.5, 8:1:1. In the above range of volume ratio, the bulk solvent and the extraction solvent with high boiling point are in a majority, so that the azeotropic point of the adjusting solvent composition can be effectively increased, so that the temperature of the solvent bath annealing process can reach the conversion temperature of the photoactive phase of the perovskite thin film, and the system itself is not easy to volatilize. In addition, the bulk solvent as the main component has high hydrophobicity, which can fully isolate the perovskite from the water vapor in the air during the solvent bath annealing process, reduce the generation of high-density defect states of the perovskite, and improve the quality of the perovskite thin film.

[0045] Further, the volume ratio of the bulk solvent, the extraction solvent, and the adjusting solvent is (7-8):(1-2):(1-2).

[0046] In some embodiments, the bulk solvent is selected from at least one of perfluorododecane, perfluorotridecane, perfluorotetradecane, perfluoropentadecane, perfluorohexadecane, perfluorotributylamine, perfluorotripentylamine, and perfluorotrihexylamine.

[0047] In some embodiments, the extraction solvent is selected from at least one of anisole, o-methylanisole, m-methylanisole, p-methylanisole, phenetol, methyl phenetol, 4-methyl phenetol, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, butyl butyrate, ethyl hexanoate, ethyl heptanoate, ethyl octanoate, hexyl acetate, heptyl acetate, pentyl propionate, hexyl butyrate, isobutyl isovalerate, butyl isovalerate, butyl valerate, isopentyl isobutyrate, isopentyl butyrate, pentyl butyrate, isopentyl isovalerate, and methyl benzoate.

[0048] In some embodiments, the adjusting solvent is selected from at least one of octane, perfluorooctane, decane, perfluorotoluene, and perfluorobiphenyl.

[0049] In some embodiments, the bulk solvent has a boiling point less than or equal to 250°C.

[0050] In some embodiments, the extraction solvent has a boiling point less than or equal to 250°C.

[0051] Therefore, the bulk solvent and the extraction solvent have an upper limit of the boiling point, which prevents the viscosity of the solvent composition from being too high, ensures that the above components can be removed by simple heat treatment after the solvent bath annealing process, and reduces the influence of the residual solvent composition on the performance of the perovskite thin film.

[0052] In a second aspect, the present application provides a method for preparing a perovskite thin film, comprising the following steps: immersing a perovskite wet film into the solvent composition provided in the first aspect, and performing a solvent bath annealing treatment to form a perovskite thin film.

[0053] In some embodiments, the temperature of the solvent bath annealing treatment is greater than or equal to the conversion temperature of the photoactive phase of the perovskite thin film. Thus, in the solvent bath annealing treatment, the non-photoactive phase of the perovskite thin film is converted into an active phase with excellent optoelectronic properties, and the solar cell device prepared from the perovskite thin film has excellent photoelectric conversion performance.

[0054] In this context, the "conversion temperature of the photoactive phase of the perovskite thin film" refers to the lowest process temperature required to convert the non-photoactive phase (e.g., yellow δ-FAPbI3 phase) in the perovskite thin film into a photoactive phase (e.g., black α-FAPbI3 phase) under the process conditions of the solvent bath annealing treatment. Specifically, this temperature can be determined by performing X-ray diffraction (XRD) analysis on the perovskite thin film obtained after the solvent bath annealing treatment at different temperatures, and by comparing the changes in the characteristic peak intensities of the photoactive phase and the non-photoactive phase of the perovskite thin film, the lowest annealing temperature required to achieve the conversion of the photoactive phase is determined as the conversion temperature of the photoactive phase of the perovskite thin film.

[0055] It can be understood that the conversion temperature of the photoactive phase of the perovskite thin film is generally affected by various factors such as its perovskite components, band gap, specific preparation process, and additives. Therefore, for those skilled in the art, the conversion temperature of the photoactive phase defined herein is a characteristic temperature related to specific systems and process conditions, which can be determined by objective experimental methods.

[0056] In some embodiments, the temperature of the solvent bath annealing treatment is 120°C to 150°C. Exemplarily, the temperature of the solvent bath annealing treatment can be, but is not limited to, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, or 150°C.

[0057] In some embodiments, the time of the solvent bath annealing treatment is 10 min to 30 min. Exemplarily, the time of the solvent bath annealing treatment can be, but is not limited to, 10 min, 15 min, 20 min, 25 min, or 30 min.

[0058] In some embodiments, the method further comprises a step of heat treating the perovskite film formed by the solvent bath annealing at a temperature lower than the temperature of the solvent bath annealing. In this way, the perovskite film formed after the solvent bath annealing is heat treated at a lower temperature to remove the residual solvent and to allow proper annealing growth of the perovskite film, which is beneficial for secondary growth of the grains and further reduces the bulk and grain boundary defects.

[0059] In some embodiments, as shown in FIG. 1, the perovskite wet film is first immersed in a solvent composition to form a perovskite film by solvent bath annealing. After the solvent bath annealing, the perovskite film is placed on a hot plate for heat treatment to dry the residual solvent composition in the perovskite film. Figure 1

[0060] In some embodiments, the heat treatment is performed at a temperature of 100-120 °C. For example, the heat treatment can be performed at a temperature of 100 °C, 105 °C, 110 °C, 115 °C, 120 °C, or any temperature within the range of 100-120 °C.

[0061] In some embodiments, the perovskite wet film is obtained by coating a perovskite precursor solution on a conductive substrate.

[0062] In this application, the conductive substrate is a conductive substrate or a combination of a conductive substrate and a hole transport layer.

[0063] In particular, the perovskite precursor solution can be coated on the conductive substrate to obtain the perovskite wet film by a coating method such as spin coating, doctor blade coating, or slot-die coating. The process parameters for coating are not particularly limited and can be adjusted according to the target thickness of the perovskite wet film. Spin coating is generally applied to small-area devices and is convenient and fast. Doctor blade coating or slot-die coating is generally applied to large-area devices and is helpful to obtain a uniform and dense wet film with good process repeatability.

[0064] In some embodiments, the perovskite precursor solution is obtained by mixing a perovskite material component and a solvent.

[0065] In some embodiments, the solvent of the perovskite precursor solution is selected from one or more of N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), and acetonitrile.

[0066] In some embodiments, the perovskite material has a chemical formula of ABX3structure, A includes one or more of formamidinium cation, methylammonium cation, rubidium ion, and cesium ion, B includes lead ion and / or tin ion, and X is a halide anion of chlorine, bromine, iodine, or a combination of pseudo-halides of thiocyanate and cyanate.​

[0067] In a third aspect of the present application, a perovskite thin film is provided, which is prepared by the method for preparing a perovskite thin film according to the second aspect.

[0068] In a fourth aspect of the present application, a solar cell is provided, which comprises the perovskite thin film according to the third aspect.

[0069] The present application does not limit the specific structure of the solar cell; in a specific embodiment, the solar cell comprises one of a perovskite single-junction cell, a perovskite / perovskite tandem cell, a perovskite / crystalline silicon tandem cell, a perovskite / organic tandem cell, and a perovskite / copper indium gallium selenide tandem cell.

[0070] In some embodiments, a method for preparing a perovskite solar cell is provided, which comprises the steps of sequentially preparing a hole transport layer, a perovskite light-absorbing layer, a passivation layer, an electron transport layer, a buffer layer, and an electrode on a conductive substrate, wherein the perovskite light-absorbing layer can be prepared by the steps for preparing a perovskite thin film described herein.

[0071] In some embodiments, the conductive substrate is selected from one of a crystalline silicon cell, a conductive glass, and a flexible conductive film.

[0072] In some embodiments, the crystalline silicon cell comprises one of a passivated emitter and rear contact cell (PERC cell), a tunnel oxide passivated contact cell (TOPCon cell), a heterojunction with intrinsic thin layer solar cell (HJT cell), and a back contact cell (IBC cell).

[0073] In some embodiments, the conductive glass has a certain degree of transparency. The conductive glass is generally composed of a glass substrate and an oxide thin film (TCO) conductive layer. The commonly used TCOs include, but are not limited to, the following materials: fluorine-doped tin oxide (FTO), indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), boron-doped zinc oxide (BZO), indium zinc oxide (IZO). The conductive glass can be any conductive glass used in the art. The conductive glass is commercially available. The conductive glass needs to be cleaned before use, for example, ultrasonic cleaning with cleaning agents, deionized water, and ethanol.

[0074] In some embodiments, the flexible conductive film comprises one of an indium tin oxide (ITO) film, a fluorine-doped tin oxide (FTO) film, an aluminum-doped zinc oxide (AZO) film, a boron-doped zinc oxide (BZO) film, and an indium zinc oxide (IZO) film.

[0075] The materials suitable for the hole transport layer include, but are not limited to, organic hole transport materials, inorganic hole transport materials, self-assembled monolayer materials, and the like.

[0076] In some embodiments, the hole transport material comprises one or more of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz for short), (2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl)phosphonic acid (MeO-2PACZ for short), (4-(3,6-dimethyl-9H-carbazol-9-yl)ethyl)phosphonic acid (Me-4PACZ for short), PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate), NiO x and CuSCN.

[0077] Suitable materials for the passivation layer include 2-thiopheneethylamine hydrochloride (TEACl), 1,4-benzenediamine hydroiodide (PDADI), phenethylamine iodide (PEAI), 1,3-diaminopropane dihydroiodide (PDAI2), and the like. The preparation of the passivation layer is not particularly limited, and methods for preparing a passivation layer conventionally used in the art can be used, such as, for example, a doctor blade coating method or a slot coating method. Process parameters can be adjusted according to the target thickness of the passivation layer.

[0078] Suitable materials for the electron transport layer include, but are not limited to, PCBM ([6,6]-phenyl-C61-butyric acid methyl ester), TiO2, SnO2, ZnO, C60, and ICBA (indene-C60 bisadduct). The preparation of the electron transport layer is not particularly limited, and methods for preparing an electron transport layer conventionally used in the art can be used, including, but not limited to, one or more of spin coating, spray coating, spray pyrolysis, slot coating, and atomic layer deposition. Process parameters can be adjusted according to the target thickness of the electron transport layer.

[0079] Suitable materials for the buffer layer include, but are not limited to, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) or MoO x (molybdenum oxide), and the like. The preparation of the buffer layer is not particularly limited, and methods for preparing a buffer layer conventionally used in the art can be used, including, but not limited to, one or more of spin coating, spray coating, spray pyrolysis, slot coating, and atomic layer deposition. Process parameters can be adjusted according to the target thickness of the buffer layer.

[0080] Suitable materials for the electrode can be selected from one or more of silver, copper, Au (gold), ITO, IZO, AZO, and IWO.

[0081] The solar cell provided by the present application can be used in, but is not limited to, an electric device such as a vehicle, a ship, or an aircraft.

[0082] Based on the same inventive concept, the present application provides a photovoltaic module comprising the solar cell in any of the above embodiments.

[0083] The solar cells can be arranged in multiple numbers, and the solar cells can be electrically connected in a whole piece or multiple pieces to form multiple cell strings, and the multiple cell strings are electrically connected in series and / or in parallel. The photovoltaic module can further include an encapsulation layer and a cover plate, the encapsulation layer is used to cover the surface of the cell string, and the cover plate is used to cover the surface of the encapsulation layer away from the cell string. Specifically, in some embodiments, the multiple cell strings can be electrically connected through a conductive ribbon. The encapsulation layer covers the surface of the solar cell. Exemplarily, the encapsulation layer can be an organic encapsulation film such as an ethylene-vinyl acetate copolymer film, a polyethylene octene elastomer film or a polyethylene terephthalate film. The cover plate can be a glass cover plate, a plastic cover plate or the like having a light-transmitting function.

[0084] Based on the same inventive concept, the embodiment of the present application provides a photovoltaic system including the photovoltaic module in any of the above embodiments.

[0085] It can be understood that the photovoltaic system can be applied in a photovoltaic power station, for example, a ground power station, a roof power station, a water surface power station and the like, and can also be applied in a device or apparatus using solar energy to generate electricity, for example, a user solar power source, a solar street lamp, a solar car, a solar building and the like. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system can be applied in all fields requiring solar energy to generate electricity. Taking a photovoltaic power generation system network as an example, the photovoltaic system can include a photovoltaic array, a combiner box and an inverter, the photovoltaic array can be an array combination of multiple photovoltaic modules, for example, multiple photovoltaic modules can form multiple photovoltaic arrays, the photovoltaic array is connected to the combiner box, the combiner box can combine the current generated by the photovoltaic array, the combined current flows through the inverter to convert into alternating current required by a power grid, and then is connected to a power network to realize solar power supply.

[0086] The present application will be further described below in combination with specific examples and comparative examples.

[0087] Unless otherwise specified, the techniques or conditions in the examples are carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. Unless otherwise specified, the reagents or instruments used are all conventional products that can be obtained commercially.

[0088] Example 1: The present example provides a solvent composition, a perovskite solar cell and a preparation method thereof.

[0089] The solvent composition comprises a main solvent, an extraction solvent and a regulating solvent. The preparation method is as follows: the main solvent perfluorotributylamine (PFTB), the extraction solvent phenetol (PT) and the regulating solvent perfluorotoluene (PFT) are mixed in a volume ratio of 7:1:2, and after uniform stirring, the solvent composition is obtained. Among them, the boiling point of the main solvent perfluorotributylamine is 177℃; the boiling point of the extraction solvent phenetol is 170℃; the polarity of the regulating solvent perfluorotoluene is between the two.

[0090] The perovskite solar cell is prepared by the following steps (1)-(7).

[0091] (1) The patterned ITO conductive glass is sequentially placed in a detergent, deionized water, acetone and isopropanol for ultrasonic treatment for 30 min, then dried with a nitrogen gun, and then placed in a ultraviolet ozone instrument for treatment for 30 min for standby.

[0092] (2) Me-4PACz and MeO-2PACz are respectively dissolved in ethanol to prepare a solution with a concentration of 0.4 mg / mL, then the two solutions are mixed in a volume ratio of 1:1 to prepare a hole transport layer solution, and ultrasonic treatment is performed for 5 minutes for standby; 194 mg of CsI, 456 mg of FAI, 47 mg of PbCl2, 252 mg of PbBr2, 1187 mg of PbI2 and 29 mg of MACl are dissolved in 2 mL of a mixed solvent of DMF and DMSO in a volume ratio of 8:1 at room temperature to prepare a perovskite precursor solution, and filtration is performed for standby; 1,3-diaminopropane dihydroiodide (PDAI2) is dissolved in a mixed solvent of isopropanol (IPA) and chlorobenzene (CB) in a volume ratio of 1:1 to prepare a passivation solution with a concentration of 1 mg / mL for standby.

[0093] (3) In the glove box, the hole transport layer solution is spin-coated on the ITO conductive substrate by using a spin coater, and the spin-coating parameters are as follows: rotation speed 3000 rpm, time 15 s, acceleration 3000 rpm / s; after spin-coating, the substrate is placed on a hot table at 100℃ for annealing for 5 min, and then taken out and cooled to room temperature for standby.

[0094] (4) The perovskite precursor solution is spin-coated on the above-mentioned hole transport layer to form a perovskite wet film with a thickness of 500 nm, and the spin-coating parameters are as follows: rotation speed 4000 rpm, time 7 s, acceleration 4000 rpm / s; after spin-coating, the substrate with the wet film is immediately transferred to a vacuum flash evaporator (VCD) for treatment for 15 s (the vacuum flash evaporator can reduce the chamber pressure from 101 kPa to below 10 Pa within 10 s); after breaking the vacuum, the perovskite wet film is quickly immersed in the above-mentioned solvent composition for solvent bath annealing treatment, and the temperature of the solvent bath annealing treatment is 120℃ and the time is 20 min.

[0095] (5) After the solvent bath annealing process is completed, the perovskite film is placed on a hot stage at 120°C for heat treatment for 5 min to dry the residual solvent composition, to obtain the perovskite film.

[0096] Figure 2 SEM test diagram of the perovskite film prepared in this example.

[0097] (6) Dynamic spin coating of a surface passivation layer is performed on the perovskite film surface, with spin coating parameters divided into two steps: the spin coating parameters of the first step are: rotation speed 300 rpm, time 5 s, acceleration 500 rpm / s, and the spin coating parameters of the second step are: rotation speed 3000 rpm, time 5 s, acceleration 5000 rpm / s; between the 3rd second and the 5th second of the first spin coating process, the passivation solution is added dropwise on the surface of the perovskite film, and after the two-step spin coating is completed, the substrate is placed on a hot stage at 100°C for annealing for 5 min.

[0098] (7) The substrate after surface passivation is transferred to a vacuum evaporation instrument, and an electron transport layer C60 (thickness 20 nm, rate 0.2 Å / s), a hole blocking layer BCP (thickness 5 nm, rate 0.1 Å / s) and a metal electrode Cu (thickness 110 nm, evaporation rate 0.2 Å / s for the first 10 nm, and evaporation rate 0.5 Å / s for the subsequent 100 nm) are sequentially evaporated to obtain a perovskite solar cell.

[0099] Example 2: The preparation method of the solvent composition and the perovskite solar cell in this example is basically the same as that in Example 1, except that the volume ratio of the main solvent perfluorotributylamine (PFTB), the extraction solvent phenetol (PT) and the adjusting solvent perfluorotoluene (PFT) is 6:1:3.

[0100] Figure 3 SEM test diagram of the perovskite film prepared in this example.

[0101] Example 3: The preparation method of the solvent composition and the perovskite solar cell in this example is basically the same as that in Example 1, except that the volume ratio of the main solvent perfluorotributylamine (PFTB), the extraction solvent phenetol (PT) and the adjusting solvent perfluorotoluene (PFT) is 5:2:3.

[0102] Example 4: The preparation method of the solvent composition and the perovskite solar cell in this example is basically the same as that in Example 1, except that the volume ratio of the main solvent perfluorotributylamine (PFTB), the extraction solvent phenetol (PT) and the adjusting solvent perfluorotoluene (PFT) is 8:0.5:1.5.

[0103] Example 5: The preparation method of the solvent composition and the perovskite solar cell in this example is basically the same as that in Example 1, except that the main solvent is replaced by perfluorododecane, the extraction solvent is replaced by 1,2-dichlorobenzene, and the adjusting solvent is replaced by octane.

[0104] Example 6: The preparation method of the solvent composition and the perovskite solar cell in this example is basically the same as that in Example 1, except that the main solvent is replaced by perfluorotrihexylamine, the extraction solvent is replaced by butyl butyrate, and the adjusting solvent is replaced by perfluorobiphenyl.

[0105] Comparative Example 1: This comparative example provides a perovskite solar cell and a preparation method thereof.

[0106] The perovskite solar cell is prepared by the following steps (1)-(6).

[0107] (1) The patterned ITO conductive glass was sequentially placed in detergent, deionized water, acetone and isopropanol for ultrasonic treatment for 30 min, then dried with a nitrogen gun, and then placed in a ultraviolet ozone instrument for treatment for 30 min for standby.

[0108] (2) Me-4PACz and MeO-2PACz were dissolved in ethanol respectively to prepare a solution with a concentration of 0.4 mg / mL, then the two solutions were mixed according to a volume ratio of 1:1 to prepare a hole transport layer solution, which was ultrasonically treated for 5 min for standby; 194 mg of CsI, 456 mg of FAI, 47 mg of PbCl2, 252 mg of PbBr2, 1187 mg of PbI2 and 29 mg of MACl were dissolved in 2 mL of mixed solvent of DMF and DMSO with a volume ratio of 8:1 at room temperature to prepare a perovskite precursor solution, which was filtered for standby; 1,3-diaminopropane dihydroiodide (PDAI2) was dissolved in a mixed solvent of isopropanol (IPA) and chlorobenzene (CB) with a volume ratio of 1:1 to prepare a passivation solution with a concentration of 1 mg / mL for standby.

[0109] (3) In the glove box, the hole transport layer solution was spin-coated on the ITO conductive substrate by using a spin coater, and the spin-coating parameters were as follows: rotation speed 3000 rpm, time 15 s, acceleration 3000 rpm / s, after spin-coating, the substrate was placed on a hot stage at 100°C for annealing for 5 min, then taken out and cooled to room temperature for standby.

[0110] (4) The perovskite precursor solution is spin-coated on the above-mentioned hole transport layer to form a perovskite wet film with a thickness of 500 nm, and the spin-coating parameters are as follows: rotation speed 4000 rpm, time 7 s, and acceleration 4000 rpm / s; after spin-coating, the substrate with the wet film is immediately transferred to a vacuum flash evaporator (VCD) for treatment for 15 s (the vacuum flash evaporator evacuates the chamber from 100 kPa to below 10 Pa within 10 s); after breaking the vacuum, the substrate is quickly placed on a hot stage at 120 ℃ for annealing for 30 min to form a perovskite thin film.

[0111] Figure 4 The SEM test diagram of the perovskite thin film prepared for the present comparative example.

[0112] (5) Dynamic spin-coating of a surface passivation layer is performed on the surface of the perovskite thin film, and the spin-coating parameters are divided into two steps: the spin-coating parameters of the first step are as follows: rotation speed 300 rpm, time 5 s, and acceleration 500 rpm / s, and the spin-coating parameters of the second step are as follows: rotation speed 3000 rpm, time 5 s, and acceleration 5000 rpm / s; during the third to fifth seconds of the first spin-coating process, the passivation solution is added dropwise on the surface of the perovskite thin film; after the two-step spin-coating, the substrate is placed on a hot stage at 100 ℃ for annealing for 5 min.

[0113] (6) The substrate with the surface passivation completed is transferred to a vacuum evaporation instrument, and an electron transport layer C60 (thickness 20 nm, rate 0.2 Å / s), a hole blocking layer BCP (thickness 5 nm, rate 0.1 Å / s), and a metal electrode Cu (thickness 110 nm, evaporation rate 0.2 Å / s for the first 10 nm, and evaporation rate 0.5 Å / s for the subsequent 100 nm) are sequentially evaporated to obtain a perovskite solar cell.

[0114] Comparative Example 2: The present comparative example provides a perovskite solar cell and a preparation method thereof.

[0115] The perovskite solar cell is prepared by the following steps (1)-(7).

[0116] (1) The patterned ITO conductive glass is sequentially subjected to ultrasonic cleaning in a detergent, deionized water, acetone, and isopropanol for 30 min, dried with a nitrogen gun, and then placed in a UV ozone instrument for treatment for 30 min for standby.

[0117] (2) Me-4PACz and MeO-2PACz were dissolved in ethanol to prepare a solution with a concentration of 0.4 mg / mL, and then the two solutions were mixed according to a volume ratio of 1:1 to prepare a hole transport layer solution, which was ultrasonically treated for 5 min for standby; 194 mg of CsI, 456 mg of FAI, 47 mg of PbCl2, 252 mg of PbBr2, 1187 mg of PbI2 and 29 mg of MACl were dissolved in 2 mL of a mixed solvent of DMF and DMSO with a volume ratio of 8:1 at room temperature to prepare a perovskite precursor solution, which was filtered for standby; 1,3-diaminopropane dihydroiodide (PDAI2) was dissolved in a mixed solvent of isopropyl alcohol (IPA) and chlorobenzene (CB) with a volume ratio of 1:1 to prepare a passivation solution with a concentration of 1 mg / mL for standby.

[0118] (3) In the glove box, the hole transport layer solution was spin-coated on the ITO conductive substrate by using a spin coater, and the spin-coating parameters were as follows: rotation speed 3000 rpm, time 15 s, acceleration 3000 rpm / s; after spin-coating, the substrate was placed on a hot stage at 100°C for annealing for 5 min, and then taken out and cooled to room temperature for standby.

[0119] (4) The perovskite precursor solution was spin-coated on the above hole transport layer to form a perovskite wet film with a thickness of 500 nm, and the spin-coating parameters were as follows: rotation speed 4000 rpm, time 7 s, acceleration 4000 rpm / s; after spin-coating, the substrate with the wet film was immediately transferred to a vacuum flash evaporator (VCD) for treatment for 15 s (the vacuum flash evaporator can reduce the chamber pressure from 100 kPa to below 10 Pa within 10 s); after breaking the vacuum, the perovskite wet film was quickly immersed in a single-component perfluorotributylamine solvent for solvent bath annealing treatment, and the temperature of the solvent bath annealing treatment was 120°C and the time was 20 min.

[0120] (5) After completing the solvent bath annealing treatment, the perovskite film was placed on a hot stage at 120°C for heat treatment for 5 min to dry the residual solvent, and a perovskite film was obtained.

[0121] Figure 5 SEM test diagram of the perovskite film prepared for the present comparative example.

[0122] (6) Dynamic spin-coating surface passivation layer on the surface of perovskite thin film, spin-coating parameters are divided into two steps: the spin-coating parameters of the first step are: rotation speed 300 rpm, time 5 s, acceleration 500 rpm / s, the spin-coating parameters of the second step are: rotation speed 3000 rpm, time 5 s, acceleration 5000 rpm / s; between the 3rd second and the 5th second of the first spin-coating process, drop the passivation solution on the surface of perovskite thin film, after the two-step spin-coating, place the substrate on a hot stage at 100℃ and anneal for 5 min.

[0123] (7) Transfer the substrate with surface passivation completed to a vacuum evaporation instrument, evaporate the electron transport layer C60 (thickness 20 nm, rate 0.2 Å / s), the hole blocking layer BCP (thickness 5 nm, rate 0.1 Å / s) and the metal electrode Cu (thickness 110 nm, evaporation rate 0.2 Å / s for the first 10 nm, evaporation rate 0.5 Å / s for the subsequent 100 nm) in sequence, to obtain the perovskite solar cell.

[0124] Comparative Example 3: The comparative example provides a perovskite solar cell and a preparation method thereof.

[0125] The perovskite solar cell is prepared by the following steps (1)-(7).

[0126] (1) Place the patterned ITO conductive glass in detergent, deionized water, acetone and isopropanol in sequence and ultrasonic for 30 min, then blow dry with a nitrogen gun, and then place in a UV-ozone instrument for treatment for 30 min for standby.

[0127] (2) Dissolve Me-4PACz and MeO-2PACz in ethanol respectively to prepare a solution with a concentration of 0.4 mg / mL, then mix the two solutions according to a volume ratio of 1:1 to prepare a hole transport layer solution, and ultrasonic for 5 min for standby; dissolve 194 mg of CsI, 456 mg of FAI, 47 mg of PbCl2, 252 mg of PbBr2, 1187 mg of PbI2 and 29 mg of MACl in 2 mL of mixed solvent of DMF and DMSO with a volume ratio of 8:1 at room temperature to prepare a perovskite precursor solution, and filter for standby; dissolve 1,3-diaminopropane dihydroiodide (PDAI2) in a mixed solvent of isopropanol (IPA) and chlorobenzene (CB) with a volume ratio of 1:1 to prepare a passivation solution with a concentration of 1 mg / mL for standby.

[0128] (3) In the glove box, the hole transport layer solution was spin-coated on the ITO conductive substrate by using a spin coater, and the spin-coating parameters were as follows: rotation speed 3000 rpm, time 15 s, acceleration 3000 rpm / s; after the spin-coating was completed, the substrate was placed on a hot table at 100 °C for annealing for 5 min, and then taken out and cooled to room temperature for standby.

[0129] (4) The perovskite precursor solution was spin-coated on the above hole transport layer to form a perovskite wet film with a thickness of 500 nm, and the spin-coating parameters were as follows: rotation speed 4000 rpm, time 7 s, acceleration 4000 rpm / s; after the spin-coating was completed, the substrate with the wet film was immediately transferred to a vacuum flash evaporator (VCD) for treatment for 15 s (the vacuum flash evaporator was used to evacuate the chamber from 100 kPa to below 10 Pa within 10 s); after the vacuum was broken, the perovskite wet film was quickly immersed in a single-component phenetol solvent for solvent bath annealing treatment, and the temperature of the solvent bath annealing treatment was 120 °C and the time was 20 min.

[0130] (5) After the solvent bath annealing treatment was completed, the perovskite thin film was placed on a hot table at 120 °C for heat treatment for 5 min to dry the residual solvent, and a perovskite thin film was obtained.

[0131] (6) Dynamic spin-coating of a surface passivation layer was performed on the surface of the perovskite thin film, and the spin-coating parameters were divided into two steps: the spin-coating parameters of the first step were as follows: rotation speed 300 rpm, time 5 s, acceleration 500 rpm / s, and the spin-coating parameters of the second step were as follows: rotation speed 3000 rpm, time 5 s, acceleration 5000 rpm / s; during the third second to the fifth second of the first step of spin-coating, the passivation solution was added dropwise on the surface of the perovskite thin film; after the two steps of spin-coating were completed, the substrate was placed on a hot table at 100 °C for annealing for 5 min.

[0132] (7) The substrate with the surface passivation completed was transferred to a vacuum evaporation instrument, and an electron transport layer C60 (thickness 20 nm, rate 0.2 Å / s), a hole blocking layer BCP (thickness 5 nm, rate 0.1 Å / s), and a metal electrode Cu (thickness 110 nm, evaporation rate 0.2 Å / s for the first 10 nm, and evaporation rate 0.5 Å / s for the subsequent 100 nm) were sequentially evaporated to obtain a perovskite solar cell.

[0133] Comparative Example 4: The comparative example provides a perovskite solar cell and a preparation method thereof.

[0134] The perovskite solar cell was prepared by using the following steps (1)-(7).

[0135] (1) The patterned ITO conductive glass was sequentially placed in detergent, deionized water, acetone and isopropanol for ultrasonic treatment for 30 min, then dried with a nitrogen gun, and then placed in a UV ozone instrument for treatment for 30 min for standby.

[0136] (2) Me-4PACz and MeO-2PACz were respectively dissolved in ethanol to prepare a solution with a concentration of 0.4 mg / mL, then the two solutions were mixed according to a volume ratio of 1:1 to prepare a hole transport layer solution, and ultrasonic treatment was performed for 5 min for standby; 194 mg of CsI, 456 mg of FAI, 47 mg of PbCl2, 252 mg of PbBr2, 1187 mg of PbI2 and 29 mg of MACl were dissolved in 2 mL of a mixed solvent of DMF and DMSO with a volume ratio of 8:1 at room temperature to prepare a perovskite precursor solution, and filtration was performed for standby; 1,3-diaminopropane dihydroiodide (PDAI2) was dissolved in a mixed solvent of isopropanol (IPA) and chlorobenzene (CB) with a volume ratio of 1:1 to prepare a passivation solution with a concentration of 1 mg / mL for standby.

[0137] (3) In the glove box, the hole transport layer solution was spin-coated on the ITO conductive substrate by using a spin coater, and the spin-coating parameters were as follows: rotation speed 3000 rpm, time 15 s, acceleration 3000 rpm / s; after spin-coating, the substrate was placed on a hot stage at 100°C for annealing for 5 min, and then taken out and cooled to room temperature for standby.

[0138] (4) The perovskite precursor solution was spin-coated on the above hole transport layer to form a perovskite wet film with a thickness of 200 nm, and the spin-coating parameters were as follows: rotation speed 4000 rpm, time 7 s, acceleration 4000 rpm / s; after spin-coating, the substrate with the wet film was immediately transferred to a vacuum flash evaporator (VCD) for treatment for 15 s (the vacuum flash evaporator can reduce the chamber pressure from 100 kPa to below 10 Pa within 10 s); after breaking the vacuum, the perovskite wet film was quickly immersed in a single-component perfluorotoluene solvent for solvent bath annealing treatment, and the temperature of the solvent bath annealing treatment was 120°C and the time was 20 min.

[0139] (5) After completing the solvent bath annealing treatment, the perovskite film was placed on a hot stage at 120°C for heat treatment for 5 min to dry the residual solvent, and a perovskite film was obtained.

[0140] (6) Dynamic spin-coating surface passivation layer on the perovskite thin film surface, spin-coating parameters are divided into two steps: the first step of spin-coating parameters are: rotation speed 300 rpm, time 5 s, acceleration 500 rpm / s, the second step of spin-coating parameters are: rotation speed 3000 rpm, time 5 s, acceleration 5000 rpm / s; between the 3rd second and the 5th second of the first step of spin-coating process, drop the passivation solution on the perovskite thin film surface, after two steps of spin-coating, place the substrate on the hot stage at 100℃ for annealing 5 min.

[0141] (7) Transfer the substrate with surface passivation to the vacuum evaporation instrument, evaporate the electron transport layer C60 (thickness 20 nm, rate 0.2 Å / s), the hole blocking layer BCP (thickness 5 nm, rate 0.1 Å / s) and the metal electrode Cu (thickness 110 nm, the evaporation rate of the first 10 nm is 0.2 Å / s, and the evaporation rate of the subsequent 100 nm is 0.5 Å / s) in sequence to obtain the perovskite solar cell.

[0142] Comparative Example 5: In this comparative example, the solvent composition and the preparation method of the perovskite solar cell are basically the same as those in Example 1, except that the solvent composition only contains the bulk solvent perfluorotributylamine (PFTB) and the extraction solvent phenetole (PT) in a volume ratio of 8:2.

[0143] Comparative Example 6: In this comparative example, the solvent composition and the preparation method of the perovskite solar cell are basically the same as those in Example 1, except that the bulk solvent is replaced by perfluoro-decalin; wherein the boiling point of the bulk solvent perfluoro-decalin is 142℃.

[0144] Comparative Example 7: In this comparative example, the solvent composition and the preparation method of the perovskite solar cell are basically the same as those in Example 1, except that the extraction solvent is replaced by chlorobenzene; wherein the boiling point of the extraction solvent chlorobenzene is 132℃.

[0145] The parameters of the solvent composition in the above examples and comparative examples are shown in Table 1 below.

[0146] Table 1: Parameters of the solvent composition in the examples and comparative examples.

[0147] Host solvent Extraction solvent Adjustment solvent Volume ratio of host solvent, extraction solvent and adjustment solvent Example 1 Perfluorotributylamine Anisole Perfluorotoluene 7:1:2 Example 2 Perfluorotributylamine Anisole Perfluorotoluene 6:1:3 Example 3 Perfluorotributylamine Anisole Perfluorotoluene 5:2:3 Example 4 Perfluorotributylamine Anisole Perfluorotoluene 8:0.5:1.5 Example 5 Perfluorododecane 1,2-Dichlorobenzene Octane 7:1:2 Example 6 Perfluorotrihexylamine Butyl butyrate Perfluorobiphenyl 7:1:2 Comparative Example 1 / / / / Comparative Example 2 Perfluorotributylamine / / / Comparative Example 3 / Anisole / / Comparative Example 4 / / Perfluorotoluene / Comparative Example 5 Perfluorotributylamine Anisole / 8:2:0 Comparative Example 6 Perfluorodecalin Anisole Perfluorotoluene 7:1:2 Comparative Example 7 Perfluorotributylamine Chlorobenzene Perfluorotoluene 7:1:2

[0148] Performance test: place the solar cells prepared in the above examples and comparative examples in a solar simulator (manufacturer: Wavelabs), under the irradiation of one solar intensity, apply bias voltage (Vp, bias voltage range: -0.1~1.3V) to the device using the test source table, and test the output current of the device to obtain the bias voltage-current density curve.

[0149] Open-circuit voltage (Voc): the terminal voltage of the battery piece without load, that is, the bias voltage value when the current density is 0 mA·cm -2

[0150] Short-circuit current density (Jsc): the output current per unit area of the battery piece when short-circuiting, that is, the current density when the bias voltage is 0 V in the bias-voltage-current density curve.

[0151] Fill factor (FF): FF = max (Vp x Jsc), wherein Vp is the bias voltage and Jsc is the short-circuit current density.

[0152] Photovoltaic cell efficiency (PCE): PCE = Voc x Jsc x FF.

[0153] The test results are shown in Table 2.

[0154] Table 2: Test results of the photoelectric performance of solar cells in the examples and comparative examples.

[0155] Voc (V) -2 Jsc (mA-cm ​ FF (%) PCE (%) Example 1 1.287 21.52 86.12 23.86 Example 2 1.291 20.77 85.28 22.86 Example 3 1.282 20.31 85.46 22.24 Example 4 1.290 20.77 84.42 22.61 Example 5 1.273 20.47 84.75 22.09 Example 6 1.273 20.13 84.88 21.75 Comparative Example 1 1.269 20.40 82.86 21.45 Comparative Example 2 1.252 20.05 83.26 20.91 Comparative Example 3 1.246 19.89 82.99 20.57 Comparative Example 4 1.259 20.13 83.15 21.08 Comparative Example 5 1.256 20.33 82.65 21.11 Comparative Example 6 1.261 20.19 83.28 21.20 Comparative Example 7 1.255 20.44 83.47 21.40

[0156] As shown in Table 2, Figures 2 to 6 As shown in Table 2,

[0157] As shown in Table 2,

[0158] As shown in Table 2,

[0159] As shown in Table 2,

[0160] ​As can be seen from Comparative Examples 1 to 6 and Comparative Examples 6 to 7, when the boiling point of the main solvent or the extraction solvent does not meet the requirement, the azeotropic point of the solvent composition cannot reach the transition temperature of the photoactive phase of the perovskite thin film, so that the phase transition of the perovskite thin film is insufficient, thereby affecting the photoelectric performance of the solar cell.

[0161] As can be seen from FIG. 1, the perovskite thin film of Example 1 has fewer surface defects and a smoother surface than the perovskite thin films of Comparative Example 1 and Comparative Example 2, and has a higher perovskite thin film quality. Figures 2 to 5

[0162] As can be seen from FIG. 2, the perovskite thin film of Example 2 has fewer surface defects and a smoother surface than the perovskite thin films of Comparative Example 1 and Comparative Example 2, and has a higher perovskite thin film quality. Figure 7 As can be seen from FIG. 3, the characteristic peak intensity of the XRD test of the perovskite thin film of Example 1 is higher than that of Comparative Example 1, which represents that the crystallinity of the perovskite thin film of Example 1 is better, and has a higher perovskite thin film quality.

[0163] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present disclosure.

[0164] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be pointed out that for ordinary skilled persons in the art, without departing from the technical concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.​

Claims

1. A solvent composition, characterized by, A solvent composition for a solvent bath annealing process to form a perovskite thin film, the solvent composition comprising: a bulk solvent having a boiling point greater than 150℃, the bulk solvent being selected from at least one of perfluoroalkane compounds and perfluoro tertiary amine compounds; an extraction solvent having a boiling point greater than 150℃, the extraction solvent being selected from at least one of aromatic ether compounds, halogenated aromatic compounds and ester compounds; and an adjustment solvent having a polarity between that of the bulk solvent and that of the extraction solvent; a temperature of the solvent bath annealing process being greater than or equal to a conversion temperature of a photoactive phase of the perovskite thin film.

2. The solvent composition of claim 1, wherein, a volume ratio of the bulk solvent, the extraction solvent and the adjustment solvent being (5-8):(0.5-2):(1-3).

3. The solvent composition of claim 2, wherein, a volume ratio of the bulk solvent, the extraction solvent and the adjustment solvent being (7-8):(1-2):(1-2).

4. The solvent composition according to any one of claims 1 to 3, characterized in that, At least one of the following conditions is satisfied: (1) the bulk solvent is selected from at least one of perfluorododecane, perfluorotridecane, perfluorotetradecane, perfluoropentadecane, perfluorohexadecane, perfluorotributylamine, perfluorotripentylamine and perfluorotrihexylamine; (2) the extraction solvent is selected from at least one of anisole, o-methylanisole, m-methylanisole, p-methylanisole, phenetol, methyl phenetol, 4-methyl phenetol, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, butyl butyrate, ethyl hexanoate, ethyl heptanoate, ethyl octanoate, hexyl acetate, heptyl acetate, pentyl propionate, hexyl butyrate, isobutyl isovalerate, butyl isovalerate, butyl valerate, isopentyl isobutyrate, isopentyl butyrate, pentyl butyrate, isopentyl isovalerate and methyl benzoate; (3) the adjustment solvent is selected from at least one of octane, perfluoro-octane, decane, perfluoro-toluene and perfluoro-biphenyl; (4) the boiling point of the bulk solvent is less than or equal to 250℃; (5) the boiling point of the extraction solvent is less than or equal to 250℃.

5. A method for preparing a perovskite thin film, characterized by, comprising the following steps: immersing a perovskite wet film into the solvent composition as claimed in any one of claims 1-4 to perform a solvent bath annealing process to form a perovskite thin film.

6. The method for preparing perovskite thin films according to claim 5, characterized in that, a temperature of the solvent bath annealing process being 120-150℃.

7. The method for preparing perovskite thin films according to claim 5 or 6, characterized in that, after the solvent bath annealing process, further comprising the following steps: performing a heat treatment on the perovskite thin film formed by the solvent bath annealing process, the heat treatment being at a temperature lower than that of the solvent bath annealing process.

8. A perovskite thin film, characterized by, obtained by using the method for preparing a perovskite thin film as claimed in any one of claims 5-7.

9. A solar cell, characterized by comprising the perovskite thin film as claimed in claim 8.

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