Perovskite precursor solution, perovskite solar cell and preparation method thereof, and photovoltaic module

Abstract

The embodiment of the invention provides a perovskite precursor solution. The perovskite precursor solution comprises a perovskite material, an organic additive and an organic solvent, wherein the organic additive comprises one or two of trifluoromethyl aromatic carboxylic acid and trifluoromethyl sulfo aromatic carboxylic acid. According to the technical scheme, the perovskite precursor solution can significantly improve the stability of a perovskite light absorption layer in a humid environment and prolong the service life of a device; and the nucleation rate and the growth process of the crystal can be adjusted, the increase of perovskite crystal grains is promoted, the grain boundary defects are reduced, the carrier recombination is reduced, and the photoelectric conversion efficiency is improved.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a perovskite precursor solution, a perovskite solar cell and a preparation method, and a photovoltaic module. Background Art

[0002] Perovskite materials have a unique crystal structure, and their energy band gap can be adjusted by adjusting the type and proportion of elements, thereby achieving efficient absorption of the solar spectrum; in addition, perovskite materials also have advantages such as long carrier lifetime and high defect tolerance; therefore, in recent years, the device performance of organic-inorganic hybrid perovskite solar cells has made great progress. However, perovskite materials have poor stability and are easily degraded in light, high temperature or humid environments, which seriously limits their commercial application.

[0003] In order to improve the stability and efficiency of perovskite materials, various additives can be added to perovskite materials, such as halogen additives and organic amine additives. Halogen additives mainly react with metal ions (such as Pb 2+ ) form weak interactions to achieve surface passivation; however, the passivation effect of this type of additive is not long-lasting. As the device is used for a longer time, the additive is easy to desorb, resulting in a gradual increase in defect states in the perovskite light-absorbing layer, which in turn affects the stability and efficiency of the device. Although organic amine additives can improve the crystal growth process of the perovskite light-absorbing layer in the short term, these organic substances themselves have poor hydrophobicity and cannot effectively block moisture or oxygen from entering the film, causing the perovskite material to decompose rapidly in a humid environment, and the long-term stability of the device cannot be guaranteed.

[0004] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the invention

[0005] The embodiments of the present application provide a perovskite precursor solution, a perovskite solar cell and a preparation method, and a photovoltaic module to solve or alleviate the technical problems mentioned above. The perovskite precursor solution of the technical solution of the present application can significantly improve the stability of the perovskite light-absorbing layer in a humid environment and extend the life of the device; it can also adjust the nucleation rate and growth process of the crystal, promote the enlargement of the perovskite grains, reduce grain boundary defects, reduce carrier recombination, and improve the photoelectric conversion efficiency.

[0006] In a first aspect, an embodiment of the present application provides a perovskite precursor solution, comprising a perovskite material, an organic additive and an organic solvent; Wherein, the organic additive includes one or both of trifluoromethyl aromatic carboxylic acid and trifluoromethylthioaromatic carboxylic acid.

[0007] Optionally, the organic additive includes one or more of trifluoromethylbenzoic acid, trifluoromethylphenylacetic acid, trifluoromethylphenylpropionic acid, trifluoromethylthiobenzoic acid, trifluoromethylthiophenylacetic acid, and trifluoromethylthiophenylpropionic acid.

[0008] Optionally, the organic additive includes one or both of trifluoromethylbenzoic acid and trifluoromethylthiobenzoic acid.

[0009] Optionally, the organic additive includes one or more of 2-(trifluoromethyl)benzoic acid, 3-(trifluoromethyl)benzoic acid, 4-(trifluoromethyl)benzoic acid, 2-(trifluoromethylthio)benzoic acid, 3-(trifluoromethylthio)benzoic acid, and 4-(trifluoromethylthio)benzoic acid.

[0010] Optionally, the organic solvent includes one or more of dimethyl sulfoxide, N,N-dimethylformamide, acetonitrile, N-methylpyrrolidone, 2-methoxyethanol and γ-butyrolactone.

[0011] Optionally, the mass ratio of the organic additive to the perovskite material is 0.5% to 5%.

[0012] Optionally, in the perovskite precursor solution, the molar concentration of the organic additive is 17.25~172.5mmol / L.

[0013] In a second aspect, an embodiment of the present application provides a perovskite solar cell, comprising: a conductive substrate, a first charge transport layer, a perovskite light absorption layer, a second charge transport layer, a blocking layer, and an electrode stacked in sequence; Wherein, the perovskite light-absorbing layer is formed by a perovskite precursor solution; The perovskite precursor solution comprises: a perovskite material, an organic additive and an organic solvent; The organic additive includes one or both of trifluoromethyl aromatic carboxylic acid and trifluoromethylthioaromatic carboxylic acid.

[0014] In a third aspect, an embodiment of the present application provides a method for preparing a perovskite solar cell, comprising: Preparing a perovskite precursor solution; wherein the perovskite precursor solution comprises a perovskite material, an organic additive and an organic solvent; the organic additive comprises one or two of trifluoromethyl aromatic carboxylic acid and trifluoromethyl thioaromatic carboxylic acid; providing a conductive substrate; forming a first charge transport layer on the conductive substrate; coating the perovskite precursor solution on the first charge transport layer to form a perovskite light absorbing layer; A second charge transport layer, a blocking layer and an electrode are sequentially formed on the perovskite light absorbing layer.

[0015] Optionally, the preparation of the perovskite precursor solution comprises: Adding the perovskite material to the organic solvent and mixing them evenly to obtain a first mixed solution; The organic additive is added to the first mixed solution and mixed evenly to obtain a perovskite precursor solution.

[0016] In a fourth aspect, an embodiment of the present application provides a photovoltaic assembly, including: At least one battery string, the battery string comprising any of the above-mentioned perovskite solar cells.

[0017] The above technical solution adopted in the embodiment of the present application may have the following advantages: The organic additives (trifluoromethyl aromatic carboxylic acid and / or trifluoromethylthioaromatic carboxylic acid) in the perovskite precursor solution have both trifluoromethyl (-CF3) and carboxylic acid groups (-COOH). The trifluoromethyl group is a strongly hydrophobic group and can form a barrier layer with strong hydrophobic properties in a humid environment, effectively blocking moisture and oxygen from entering the perovskite light-absorbing layer, which can significantly improve the stability of the perovskite light-absorbing layer in a humid environment and extend the life of the device. In addition, the carboxylic acid group can form a strong coordination bond with the metal ions (such as Pb²⁺) on the surface of the perovskite, thereby having a long-term and stable passivation effect, so that the organic additives will not be easily desorbed during long-term use, and can continuously reduce the defect state density on the surface and grain boundaries, reduce non-radiative recombination, and improve the stability and efficiency of the device. The perovskite precursor solution in the embodiment of the present application adjusts the nucleation rate and growth process of the crystal through organic additives (trifluoromethyl aromatic carboxylic acid and / or trifluoromethyl thioaromatic carboxylic acid), promotes the increase of perovskite grains, and reduces grain boundary defects, thereby reducing carrier recombination and improving photoelectric conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0019] Figure 1 It is a schematic diagram of the structure of a perovskite solar cell provided in an embodiment of the present application.

[0020] Description of reference numerals: 10. Conductive substrate; 20. First charge transport layer; 30. Perovskite light absorption layer; 40. Second charge transport layer; 50. Blocking layer; 60. Electrode. DETAILED DESCRIPTION

[0021] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. In the accompanying drawings, for clarity, the sizes of layers, regions, elements and their relative sizes may be exaggerated. Wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limitations on the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0022] It should be understood that when an element or layer is referred to as "on", "under", "adjacent to", "connected to" or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as "directly on", "under", "directly adjacent to", "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present disclosure, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part. When a second element, component, region, layer or section is discussed, it does not necessarily mean that the first element, component, region, layer or section must be present in the present disclosure.

[0023] In this application, unless otherwise clearly specified and limited, the terms "set", "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0024] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0025] Hereinafter, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. It should be noted that these exemplary embodiments can be implemented in many different forms and should not be construed as being limited to the embodiments described herein.

[0026] The embodiment of the present application provides a perovskite precursor solution, including a perovskite material, an organic additive and an organic solvent; The organic additive includes one or both of trifluoromethyl aromatic carboxylic acid and trifluoromethylthioaromatic carboxylic acid.

[0027] In the embodiments of the present application, the organic additive (trifluoromethyl aromatic carboxylic acid and / or trifluoromethylthioaromatic carboxylic acid) has both a trifluoromethyl group (-CF3) and a carboxylic acid group (-COOH). The trifluoromethyl group is a strongly hydrophobic group and can form a barrier layer with strong hydrophobic properties in a humid environment, effectively blocking moisture and oxygen from entering the perovskite light-absorbing layer, and can significantly improve the stability of the perovskite light-absorbing layer in a humid environment and extend the life of the device; in addition, the carboxylic acid group can form a strong coordination bond with the metal ions (such as Pb²⁺) on the surface of the perovskite, thereby having a long-term and stable passivation effect, so that the organic additive will not be easily desorbed during long-term use, and can continuously reduce the defect state density on the surface and grain boundaries, reduce non-radiative recombination, and improve the stability and efficiency of the device. The perovskite precursor solution in the embodiment of the present application adjusts the nucleation rate and growth process of the crystal through organic additives (trifluoromethyl aromatic carboxylic acid and / or trifluoromethyl thioaromatic carboxylic acid), promotes the increase of perovskite grains, and reduces grain boundary defects, thereby reducing carrier recombination and improving photoelectric conversion efficiency.

[0028] In the embodiments of the present application, trifluoromethyl aromatic carboxylic acid refers to an aromatic compound containing both a trifluoromethyl group and a carboxylic acid group but no other heteroatoms; trifluoromethylthioaromatic carboxylic acid refers to an aromatic compound containing both a trifluoromethyl group, a thio group (-S-CF3) and a carboxylic acid group but no other heteroatoms.

[0029] In some embodiments, the organic additive includes one or more of trifluoromethylbenzoic acid, trifluoromethylphenylacetic acid, trifluoromethylphenylpropionic acid, trifluoromethylthiobenzoic acid, trifluoromethylthiophenylacetic acid, and trifluoromethylthiophenylpropionic acid.

[0030] The above-mentioned organic additives have relatively small molecular weights and relatively simple molecular structures, and have good compatibility with perovskite materials and transport layers (such as electron transport layers and hole transport layers), which helps to form a smooth perovskite light-absorbing layer, reduce light scattering and loss, and thus improve the overall device performance; in addition, the above-mentioned organic additives can make the surface of the perovskite light-absorbing layer have a uniform covering layer, effectively improve the interface contact between the perovskite light-absorbing layer and the transport layer, and improve the charge transfer efficiency.

[0031] It should be noted that among the substances such as trifluoromethylbenzoic acid, trifluoromethylphenylacetic acid, trifluoromethylphenylpropionic acid, trifluoromethylthiobenzoic acid, trifluoromethylthiophenylacetic acid, and trifluoromethylthiophenylpropionic acid, each substance is not a compound but a class of compounds. For example, trifluoromethylbenzoic acid includes one or more of 2-(trifluoromethyl)benzoic acid, 3-(trifluoromethyl)benzoic acid, 4-(trifluoromethyl)benzoic acid, 2,3-bis(trifluoromethyl)benzoic acid, 2,4-bis(trifluoromethyl)benzoic acid, 3,4-bis(trifluoromethyl)benzoic acid, 2,3,4-tris(trifluoromethyl)benzoic acid, and 2,4,6-tris(trifluoromethyl)benzoic acid. The trifluoromethylthiobenzoic acid includes one or more of 2-(trifluoromethylthio)benzoic acid, 3-(trifluoromethylthio)benzoic acid, 4-(trifluoromethylthio)benzoic acid, 2,3-bis(trifluoromethylthio)benzoic acid, 2,4-bis(trifluoromethylthio)benzoic acid, 3,4-bis(trifluoromethylthio)benzoic acid, 2,3,4-tris(trifluoromethylthio)benzoic acid, and 2,4,6-tris(trifluoromethylthio)benzoic acid.

[0032] In some embodiments, the organic additive includes one or both of trifluoromethylbenzoic acid and trifluoromethylthiobenzoic acid.

[0033] The benzoic acid group in trifluoromethylbenzoic acid and trifluoromethylthiobenzoic acid is a rigid structure, which makes the chemical structure more stable, can enhance the ability of the molecule to resist high-temperature decomposition, can maintain its functional characteristics at higher temperatures, and reduce the performance degradation caused by thermal decomposition, so that the perovskite light-absorbing layer still has good crystal stability and structural integrity under high temperature environment, thereby improving the thermal stability of perovskite solar cells and greatly enhancing the durability of the device. In addition, in addition to trifluoromethyl and carboxylic acid groups, trifluoromethylthiobenzoic acid also contains a sulfur group (-S-). The sulfur group contains a lone pair of electrons and can react with Pb +The coordination can further improve the surface passivation effect, and the sulfur group is located between the trifluoromethyl group and the benzoic acid group, which can balance the strong electron-withdrawing effect of the trifluoromethyl group and the electronic effect of the benzene ring, thereby further improving the overall stability of the molecule and allowing the molecule to maintain its functional properties at high temperatures.

[0034] In some embodiments, the organic additive includes one or more of 2-(trifluoromethyl)benzoic acid, 3-(trifluoromethyl)benzoic acid, 4-(trifluoromethyl)benzoic acid, 2-(trifluoromethylthio)benzoic acid, 3-(trifluoromethylthio)benzoic acid, and 4-(trifluoromethylthio)benzoic acid.

[0035] In some embodiments, the organic solvent includes one or more of dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), acetonitrile (ACN), N-methylpyrrolidone (NMP), 2-methoxyethanol (2-Me), and gamma-butyrolactone (GBL).

[0036] This type of organic solvent can not only dissolve perovskite materials well, but also has good compatibility with trifluoromethyl aromatic carboxylic acid and trifluoromethylthioaromatic carboxylic acid, which helps to form a barrier layer with strong hydrophobic properties and continuously reduce the defect state density on the surface and grain boundaries, forming a uniform and dense perovskite light-absorbing layer, thereby improving the photoelectric conversion efficiency and stability of the device.

[0037] In some embodiments, the mass ratio of the organic additive to the perovskite material is 0.5% to 5%.

[0038] When the mass ratio of the organic additive to the perovskite material is 0.5% to 5%, the growth of the perovskite light-absorbing layer can be effectively regulated, which helps to reduce defects in the perovskite light-absorbing layer and improve the photoelectric conversion efficiency of solar cells. Specifically, the mass ratio of the organic additive to the perovskite material is 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%.

[0039] In some embodiments, in the perovskite precursor solution, the molar concentration of the organic additive is 17.25-172.5 mmol / L.

[0040] When the molar concentration of the organic additive in the perovskite precursor solution is 17.25~172.5mmol / L, it can not only effectively block moisture and oxygen from entering the perovskite light-absorbing layer and extend the life of the device, but also control the crystallization rate of the perovskite, which helps to form a uniform and dense perovskite light-absorbing layer, further reduce the defect state density on the surface and grain boundaries, reduce non-radiative recombination, and improve the stability and efficiency of the device. Specifically, in the perovskite precursor solution, the molar concentration of the organic additive is 17.25mmol / L, 51.75mmol / L, 60.8mmol / L, 69mmol / L, 76.5mmol / L, 77.6mmol / L, 86.25mmol / L, 103.5mmol / L, 138mmol / L or 172.5mmol / L.

[0041] like Figure 1 As shown, the embodiment of the present application provides a perovskite solar cell, comprising a conductive substrate 10, a first charge transport layer 20, a perovskite light absorption layer 30, a second charge transport layer 40, a blocking layer 50, and an electrode 60 which are stacked in sequence; Wherein, the perovskite light absorbing layer 30 is formed from a perovskite precursor solution; The perovskite precursor solution includes: a perovskite material, an organic additive and an organic solvent; The organic additive includes one or both of trifluoromethyl aromatic carboxylic acid and trifluoromethylthioaromatic carboxylic acid.

[0042] In the embodiment of the present application, the perovskite solar cell may be a single-junction perovskite solar cell or a tandem perovskite solar cell. The single-junction perovskite solar cell may be a formal single-junction perovskite solar cell or an inverted single-junction perovskite solar cell; the tandem perovskite solar cell may be a perovskite / perovskite tandem solar cell, a perovskite / crystalline silicon tandem solar cell, or a perovskite / CIGS tandem solar cell.

[0043] According to the different charge transfer directions, perovskite solar cells can be divided into formal perovskite solar cells and inverted perovskite solar cells. When the first charge transfer layer is a hole transfer layer and the second charge transfer layer is an electron transfer layer, the device structure is an inverted perovskite solar cell; when the first charge transfer layer is an electron transfer layer and the second charge transfer layer is a hole transfer layer, the device structure is a formal perovskite solar cell.

[0044] In an optional embodiment, the conductive substrate includes a flexible substrate or a rigid substrate, and the rigid substrate includes ITO (indium tin oxide) transparent conductive glass, FTO (fluorine-doped tin oxide) transparent conductive glass, IWO (tungsten-doped indium oxide) transparent conductive glass or AZO (aluminum-doped zinc oxide) transparent conductive glass.

[0045] In an optional embodiment, the perovskite material is an organic-inorganic hybrid ABX3 type perovskite material, wherein A is a monovalent cation, including but not limited to a cesium ion (Cs + ), rubidium ions (Rb + ), methylamine cation (CH3NH3 + ), carboxamidino cation (CH2(NH2)2 + ) is a mixture of one or more of: B is a divalent cation, including but not limited to lead ions (Pb 2+ ), copper ions (Cu 2+ )、Zn ion(Zn 2+ ), gallium ions (Ga 2+ ), tin ions (Sn 2+ ), calcium ions (Ca 2+ ) or a mixture of one or more thereof; X is a monovalent anion, including but not limited to iodide ion (I - ), bromide ion (Br - ), chloride ion (Cl - ), fluoride ion (F - ), thiocyanate ion (SCN - ) is a mixture of one or more of the following.

[0046] In an optional embodiment, the thickness of the perovskite light absorbing layer is 10 nm-100 μm, and the band gap of the perovskite light absorbing layer is 1.66-3.0 eV. The perovskite light absorbing layer can be prepared by a slit coating method. The thickness of the perovskite light absorbing layer can also be 1200-1400 nm.

[0047] In an optional embodiment, the material of the hole transport layer includes but is not limited to [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid (Me-4PACz), benzoic acid, 4-[bis(2,4-dimethoxybiphenyl-4-yl)amino]-biphenyl-4-carboxylic acid [MC-43], 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Sprio-OMeTAD), polyethylene terephthalate (PTAA), 3-hexylthiophene polymer (P3HT), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), One or more of 2,2',7,7'-tetrakis(di-p-tolylamino)spiro-9,9'-difluorene (Spiro-TTB), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanodimethyl-p-benzoquinone (F4-TCNQ), 2,2'-(perfluoronaphthalene-2,6-diylidene)dimalononitrile (F6TCNNQ), 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline] (TAPC). The hole transport layer can be prepared by slit coating, solution spin coating, vacuum evaporation, magnetron sputtering, atomic layer deposition, etc. The thickness of the hole transport layer can be 20-40nm.

[0048] In an optional embodiment, the material of the electron transport layer includes but is not limited to TiO2, SnO2, ZnO, ZrO2, gallium zinc oxide (GZO), indium zinc oxide (IZO), fluorine-doped tin oxide (FTO), indium tin oxide (ITO), BaSnO3, TiSnO x SnZnO x , fullerene, and one or more of fullerene derivatives. Exemplarily, fullerene can be selected from C 60 , C 70 One or two of the above, the fullerene derivative can be selected from PCBM (such as [6,6]-phenyl-C61-butyric acid isomethyl ester, [6,6]-phenyl-C71-butyric acid isomethyl ester). The electron transport layer can be prepared by thermal evaporation, slit coating, vacuum evaporation, magnetron sputtering, atomic layer deposition and other methods. The thickness of the electron transport layer can be 20-40nm.

[0049] In an optional embodiment, the blocking layer is an electron blocking layer, and the material of the electron blocking layer includes but is not limited to one or more of SnO2, TiO2, BCP, ZnO, and ZrO2. The blocking layer can be prepared by atomic layer deposition.

[0050] In an optional embodiment, the electrode may be a metal electrode or a transparent conductive electrode, wherein the material of the metal electrode includes but is not limited to one of Au, Ag, Al, and Cu, and the transparent conductive electrode includes one of indium tin oxide, indium zinc oxide, tungsten-doped indium oxide, and aluminum-doped zinc oxide. The electrode may be prepared by thermal evaporation, vacuum evaporation, sputtering, atomic layer deposition, 3D printing, screen printing, inkjet printing, and the like. The thickness of the electrode may be 1 nm-10 μm.

[0051] The present application provides a method for preparing a perovskite solar cell, comprising: S100: preparing a perovskite precursor solution; wherein the perovskite precursor solution comprises a perovskite material, an organic additive and an organic solvent; the organic additive comprises one or two of trifluoromethyl aromatic carboxylic acid and trifluoromethyl thioaromatic carboxylic acid; S200: providing a conductive substrate; S300: forming a first charge transport layer on a conductive substrate; S400: coating a perovskite precursor solution on the first charge transport layer to form a perovskite light absorbing layer; S500: forming a second charge transport layer, a blocking layer and an electrode in sequence on the perovskite light absorption layer.

[0052] In some embodiments, step S100, preparing a perovskite precursor solution, comprises: S110: adding the perovskite material to the organic solvent and mixing them evenly to obtain a first mixed solution; S120: adding an organic additive to the first mixed solution and mixing them evenly to obtain a perovskite precursor solution.

[0053] The preparation method of the perovskite precursor solution of the embodiment of the present application is simple and convenient. The organic additive is directly added to the first mixed solution containing the perovskite material and the organic solvent, and the mixture is uniformly mixed without the need for additional post-treatment or complicated process steps (for example, multi-step surface modification or post-passivation process). The preparation method has a simple process flow, low production cost, and wide practical application value.

[0054] In some embodiments, in step S200, the provided conductive substrate may be cleaned and treated with ultraviolet ozone. The step of cleaning the conductive substrate may include: placing the conductive substrate in an ultrasonic cleaning instrument, and ultrasonically cleaning it with a detergent: deionized water (volume ratio of 1:20), deionized water, and anhydrous ethanol, respectively, with the cleaning time of each link being 20-30 minutes, and finally drying with nitrogen. The step of ultraviolet ozone treating the conductive substrate may include: treating the conductive substrate with UV-O3, wherein the treatment time is 10-20 minutes.

[0055] In some embodiments, in step S300, the first charge transport layer is a hole transport layer; forming the hole transport layer on the conductive substrate includes: dissolving the material of the hole transport layer in anhydrous ethanol to obtain a hole transport layer precursor solution, coating the hole transport layer precursor solution on the conductive substrate by a slit coating method, and then annealing to form the hole transport layer. The annealing temperature can be 100°C and the annealing time can be 10 minutes. When the first charge transport layer is a hole transport layer, the second charge transport layer formed in step S500 is an electron transport layer.

[0056] In some embodiments, step S400, forming the perovskite light absorbing layer includes: coating the perovskite precursor solution on the first charge transport layer by a slit coating method to obtain a perovskite film, and then annealing the perovskite film to form the perovskite light absorbing layer. The annealing temperature may be 130° C., and the annealing time may be 20 min.

[0057] In some embodiments, in step S500, the material of the electron transport layer is deposited on the perovskite light absorbing layer by thermal evaporation to form a second charge transport layer (electron transport layer); the material of the blocking layer is deposited on the second charge transport layer by atomic layer deposition to form a blocking layer; and the electrode material is deposited on the blocking layer by thermal evaporation to form an electrode.

[0058] The embodiment of the present application provides a photovoltaic module (not shown), including at least one battery string, the battery string including the perovskite solar cell in any of the above embodiments. The photovoltaic module also has the advantages of the above perovskite solar cell, which will not be repeated here.

[0059] The following specific examples further illustrate the present application, but should not be construed as limiting the present application. Without departing from the spirit and substance of the present application, modifications or replacements made to the methods, steps or conditions of the present application are within the scope of the present application.

[0060] Example 1 like Figure 1 As shown, the specific structure of the perovskite solar cell of Example 1 is: A conductive substrate 10, a first charge transport layer 20, a perovskite light absorption layer 30, a second charge transport layer 40, a blocking layer 50, and an electrode 60 are sequentially stacked.

[0061] The specific preparation process of the perovskite solar cell of Example 1 is as follows: The present application provides a method for preparing a perovskite solar cell, comprising: S110a: Perovskite materials (FA 0.9 Cs 0.1PbI3) is added into the organic solvent (DMF and DMSO), mixed evenly, and a first mixed solution is obtained; S120a: adding an organic additive to the first mixed solution, mixing evenly, to obtain a perovskite precursor solution; the organic additive is 4-(trifluoromethylthio)benzoic acid; the mass ratio C1 of the organic additive to the perovskite material is 1%; in the perovskite precursor solution, the molar concentration C2 of the organic additive is 34.5 mmol / L.

[0062] S200a: providing a conductive substrate, wherein the conductive substrate is FTO transparent conductive glass; S300a: dissolving the hole transport layer material (Me-4PACz) in anhydrous ethanol to obtain a hole transport layer precursor solution, coating the hole transport layer precursor solution on a conductive substrate using a slit coating method, and then performing annealing to form a first charge transport layer (hole transport layer); S400a: coating a perovskite precursor solution on the first charge transport layer by a slit coating method to obtain a perovskite film, and then annealing the perovskite film to form a perovskite light absorbing layer; S500a: Using thermal evaporation method, C 60 Deposited on the perovskite light-absorbing layer to form a second charge transport layer (electron transport layer); SnO2 is deposited on the second charge transport layer by atomic layer deposition to form a blocking layer; Cu is deposited on the blocking layer by thermal evaporation to form an electrode.

[0063] Example 2-Example 14 The perovskite solar cells of Examples 2 to 14 were prepared by referring to the preparation method of Example 1, except that the formulas of the perovskite precursor solutions of Examples 2 to 14 were different. The formulas of the perovskite precursor solutions of Examples 2 to 14 are shown in Table 1.

[0064] In order to more clearly illustrate the technical effects of the embodiments of the present application, the present application also points out the structure and preparation method of the perovskite solar cell of Comparative Example 1.

[0065] Comparative Example 1 The perovskite solar cell of Comparative Example 1 was prepared by referring to the preparation method of Example 1, except that the formula of the perovskite precursor solution of Comparative Example 1 was different. The formula of the perovskite precursor solution of Comparative Example 1 is shown in Table 1.

[0066] Table 1 Formulas of perovskite precursor solutions of Examples 2-14 and Comparative Example 1

[0067] Table 1 (Continued) Formulations of perovskite precursor solutions of Examples 2-14 and Comparative Example 1

[0068] The perovskite solar cells of Examples 1-14 of the present application and Comparative Example 1 are respectively prepared into photovoltaic modules, and the performance of the photovoltaic modules is tested to obtain the open circuit voltage Voc, short circuit current density Jsc, fill factor FF, and photoelectric conversion efficiency PCE of the corresponding photovoltaic modules. The test results are shown in Table 2.

[0069] Table 2 Performance test results of perovskite solar cells of Examples 1-14 and Comparative Example 1

[0070] It can be seen from Table 2 that compared with Comparative Example 1, the perovskite solar cells of Examples 1-14 of the present application have higher photoelectric conversion efficiency, and all performance parameters are improved, among which the open circuit voltage and short circuit current are improved most significantly, and the open circuit voltage is increased by up to 150mV. This shows that organic additives (trifluoromethyl aromatic carboxylic acid, trifluoromethyl thioaromatic carboxylic acid) can significantly improve the crystallization quality of the perovskite light absorption layer, effectively reduce the defect state density, and improve the performance of perovskite solar cell devices.

[0071] In summary, in the embodiments of the present application, the organic additive (trifluoromethyl aromatic carboxylic acid and / or trifluoromethylthioaromatic carboxylic acid) has both a trifluoromethyl group (-CF3) and a carboxylic acid group (-COOH). The trifluoromethyl group is a strongly hydrophobic group and can form a barrier layer with strong hydrophobic properties in a humid environment, effectively blocking moisture and oxygen from entering the perovskite light-absorbing layer, and can significantly improve the stability of the perovskite light-absorbing layer in a humid environment and extend the life of the device; in addition, the carboxylic acid group can form a strong coordination bond with the metal ions (such as Pb²⁺) on the surface of the perovskite, thereby having a long-term and stable passivation effect, so that the organic additive will not be easily desorbed during long-term use, and can continuously reduce the defect state density on the surface and grain boundaries, reduce non-radiative recombination, and improve the stability and efficiency of the device. The perovskite precursor solution in the embodiment of the present application adjusts the nucleation rate and growth process of the crystal through organic additives (trifluoromethyl aromatic carboxylic acid and / or trifluoromethyl thioaromatic carboxylic acid), promotes the increase of perovskite grains, and reduces grain boundary defects, thereby reducing carrier recombination and improving photoelectric conversion efficiency.

[0072] The embodiment of the present application can provide a photovoltaic system, including the photovoltaic module in any of the above embodiments. The advantages of the above photovoltaic modules are also possessed by the photovoltaic system, which will not be repeated here. The above photovoltaic system has a wide range of applications, not only limited to photovoltaic power stations, such as ground power stations, rooftop power stations and water power stations, but also includes various equipment and devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars and solar buildings. 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 used in all fields where solar energy is required for power generation. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple photovoltaic modules. For example, multiple photovoltaic modules may form multiple photovoltaic arrays. The photovoltaic array is connected to a junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid, and then connected to the mains network to realize solar power supply.

[0073] It should be noted that the terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The orientation words "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Therefore, the exemplary term "above..." can include both "above..." and "below..." orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here are interpreted accordingly.

[0074] It should also be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0075] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0076] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A perovskite precursor solution, characterized in that: including perovskite materials, organic additives and organic solvents; Wherein, the organic additive includes one or both of trifluoromethyl aromatic carboxylic acid and trifluoromethylthioaromatic carboxylic acid.

2. The perovskite precursor solution according to claim 1, characterized in that The organic additive includes one or more of trifluoromethylbenzoic acid, trifluoromethylphenylacetic acid, trifluoromethylphenylpropionic acid, trifluoromethylthiobenzoic acid, trifluoromethylthiophenylacetic acid, and trifluoromethylthiophenylpropionic acid.

3. The perovskite precursor solution according to claim 1, characterized in that The organic additive includes one or both of trifluoromethylbenzoic acid and trifluoromethylthiobenzoic acid.

4. The perovskite precursor solution according to claim 1, characterized in that The organic additive includes one or more of 2-(trifluoromethyl)benzoic acid, 3-(trifluoromethyl)benzoic acid, 4-(trifluoromethyl)benzoic acid, 2-(trifluoromethylthio)benzoic acid, 3-(trifluoromethylthio)benzoic acid, and 4-(trifluoromethylthio)benzoic acid.

5. The perovskite precursor solution according to claim 1, characterized in that The organic solvent includes one or more of dimethyl sulfoxide, N,N-dimethylformamide, acetonitrile, N-methylpyrrolidone, 2-methoxyethanol and γ-butyrolactone.

6. The perovskite precursor solution according to claim 1, characterized in that: The mass ratio of the organic additive to the perovskite material is 0.5% to 5%.

7. The perovskite precursor solution according to claim 1, characterized in that: In the perovskite precursor solution, the molar concentration of the organic additive is 17.25-172.5 mmol / L.

8. A perovskite solar cell, characterized in that: include: A conductive substrate, a first charge transport layer, a perovskite light absorption layer, a second charge transport layer, a blocking layer, and an electrode are sequentially stacked; Wherein, the perovskite light-absorbing layer is formed by a perovskite precursor solution; The perovskite precursor solution comprises: a perovskite material, an organic additive and an organic solvent; The organic additive includes one or both of trifluoromethyl aromatic carboxylic acid and trifluoromethylthioaromatic carboxylic acid.

9. A method for preparing a perovskite solar cell, characterized in that: include: Preparing a perovskite precursor solution; wherein the perovskite precursor solution comprises a perovskite material, an organic additive and an organic solvent; the organic additive comprises one or two of trifluoromethyl aromatic carboxylic acid and trifluoromethyl thioaromatic carboxylic acid; providing a conductive substrate; forming a first charge transport layer on the conductive substrate; coating the perovskite precursor solution on the first charge transport layer to form a perovskite light absorbing layer; A second charge transport layer, a blocking layer and an electrode are sequentially formed on the perovskite light absorbing layer.

10. The method for preparing a perovskite solar cell according to claim 9, characterized in that: The method of preparing the perovskite precursor solution comprises: Adding the perovskite material to the organic solvent and mixing them evenly to obtain a first mixed solution; The organic additive is added to the first mixed solution and mixed evenly to obtain a perovskite precursor solution.

11. A photovoltaic module, characterized in that: include: At least one cell string, the cell string comprising the perovskite solar cell according to claim 8.

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