Solution, perovskite thin film preparation method, perovskite thin film and solar cell

Abstract

The invention relates to the technical field of perovskite thin films, in particular to a solution, a preparation method of a perovskite thin film, the perovskite thin film and a solar cell. The solution is used for a perovskite-based film, the perovskite-based film comprises a compound with a general formula of ABX3, A represents an organic amine cation or an inorganic cation, B represents a metal cation, X represents a halide ion or a pseudo-halogen anion, and the solution comprises an etching agent used for etching the surface of the perovskite-based film to make the surface of the perovskite-based film segregated to form a BX2 compound; and the main passivator is used for reacting with the BX2 compound so as to form a two-dimensional perovskite layer on the surface of the perovskite base film. According to the solution provided by the invention, through the synergistic effect of the etching agent and the main passivator, the universality and reproducibility of the process are improved, the perovskite thin film is uniformly and effectively passivated, low-cost and high-reproducibility product tape-out is carried out in a production line, and the error-tolerant rate in the surface passivation process is improved.

Description

Technical Field

[0001] The present application relates to the technical field of perovskite thin films, and particularly to a solution, a preparation method of a perovskite thin film, a perovskite thin film, and a solar cell. Background Art

[0002] With the development of photovoltaic, electroluminescent, and photodetective technologies, perovskite thin films and their surface passivation technologies have moved from the laboratory to large-scale industrial applications. A large number of uncoordinated ions (such as Pb 2+ , I - vacancies, etc.) exist at the surface and grain boundaries of perovskite thin films, leading to non-radiative recombination, causing interface energy level mismatch, affecting the carrier extraction process, and ultimately affecting the device performance.

[0003] Currently, there are mainly the following three passivation methods for perovskite thin films: (1) Bulk passivation of the thin film: adding a passivation material to the perovskite precursor solution to achieve passivation during the thin film preparation process; (2) Solution-based interface passivation: dissolving and coating the passivation material on the substrate before / after the deposition of the perovskite thin film; (3) Dry interface passivation: preparing the passivation material on the substrate by thermal evaporation or other methods before / after the deposition of the perovskite thin film.

[0004] However, they each have the following problems: (1) For traditional bulk passivation technologies of thin films, due to the differences in different perovskite formulations, it is necessary to specifically select a passivation agent that matches it, and the crystallization nucleation process is greatly affected by the environment, making it difficult to adapt to multiple formulations; (2) Traditional solution-based interface passivation is limited by coating technologies, and it is easy to cause passivation with a passivation agent with too high or too low concentration, and it is difficult to selectively bind and react with surface uncoordinated ions, resulting in non-uniform formation of the surface passivation layer and low passivation efficiency; (3) Although traditional dry interface passivation technologies can form uniform thin films, they cannot selectively react with the surface of perovskite thin films. Both too thin and too thick passivation layers are not conducive to the carrier extraction process, resulting in significant differences in the performance of the finally prepared devices and seriously affecting the yield. Summary of the Invention

[0005] Based on this, it is necessary to provide a solution, a preparation method of a perovskite thin film, a perovskite thin film, and a solar cell, which can improve the versatility and reproducibility of the process, uniformly and effectively passivate the perovskite thin film, perform low-cost and highly reproducible product wafering in the production line, and improve the fault tolerance rate in the surface passivation process.

[0006] The first aspect of the present application provides a solution for a perovskite-based film, the perovskite-based film comprising a compound of the general formula ABX3, wherein A represents an organic amine cation or an inorganic cation, B represents a metal cation, and X represents a halide ion or an anion of a pseudohalogen. The solution includes an etchant for etching the surface of the perovskite-based film to cause the surface precipitation of a BX2 compound on the perovskite-based film; and a main passivator for reacting with the BX2 compound to form a two-dimensional perovskite layer on the surface of the perovskite-based film.

[0007] In some embodiments, the etchant includes an A-site etchant for etching the A-site cation, and the A-site etchant includes at least one of isopropyl alcohol, trifluoroethanol, and n-butanol.

[0008] In some embodiments, the etchant further includes a B-site complexing agent for complexing the B-site cation, and the B-site complexing agent includes at least one of dimethyl sulfoxide, N-methylpyrrolidone, and 1,3-dimethyl-3,4,5,6-tetrahydro-2-pyrimidinone.

[0009] In some embodiments, the volume percentage of the B-site complexing agent in the etchant is 0.01% to 1%.

[0010] In some embodiments, the main passivator has a spacer cation, and the spacer cation includes at least one of ethylenediamine cation, benzylamine cation, phenethylamine cation, 4-trifluoromethylphenethylamine cation, propanediamine cation, and piperazine cation.

[0011] In some embodiments, the solution further includes an auxiliary passivator selected from at least one of methylammonium hydroiodide, formamidinium hydroiodide, methylammonium hydrobromide, and formamidinium hydrobromide.

[0012] In some embodiments, the solution further includes a buffer selected from at least one of toluene, ethyl acetate, diethyl ether, chlorobenzene, and acetone.

[0013] The second aspect of the present application provides a method for preparing a perovskite thin film, the method including the following steps: soaking a perovskite-based film with the solution provided in the first aspect above to form a two-dimensional perovskite layer on the surface of the perovskite-based film, thereby obtaining a perovskite thin film.

[0014] The third aspect of the present application provides a perovskite thin film prepared by the method for preparing a perovskite thin film provided in the second aspect above. The perovskite thin film includes a perovskite-based film; and a two-dimensional perovskite layer disposed on the surface of the perovskite-based film.

[0015] The fourth aspect of the present application provides a solar cell, which includes a perovskite thin film prepared by using the method for preparing a perovskite thin film provided in the second aspect above or the perovskite thin film provided in the third aspect above.

[0016] Compared with the traditional technology, the present application has at least the following beneficial effects: The solution provided by the present application, through the synergistic effect of an etchant and a main passivator, selectively etches the surface of the perovskite base film by using the etchant, so that BX2 compounds are segregated on its surface, and a two-dimensional perovskite passivation layer is formed by the in-situ reaction of the main passivator with BX2, which can passivate the defects on the surface of the perovskite base film, reduce non-radiative recombination, and reduce the interfacial energy level mismatch, thereby promoting carrier extraction and improving device performance. Further, by using the solution provided by the present application, on the one hand, there is no need to select a specific passivator for different perovskite formulations, which has better generality and reproducibility, can adapt to a variety of perovskite formulations, and avoids the problem of poor passivation effect caused by formulation differences; on the other hand, a uniform two-dimensional perovskite passivation layer can be formed, realizing uniform and effective passivation of the surface of a large-area perovskite base film, avoiding the problems of uneven passivator concentration in traditional solution interface passivation and difficult control of the passivation layer thickness in traditional dry interface passivation, improving the passivation efficiency, and at the same time enabling low-cost and highly reproducible product wafering in the production line, and improving the fault tolerance rate in the surface passivation process. Description of the Drawings

[0017] Figure 1 It is a scanning electron microscope (SEM) test diagram of the perovskite thin film in Example 1 of the present application.

[0018] Figure 2 It is a photoluminescence spectrum (PL) test diagram of the perovskite thin film in Example 1 of the present application. Detailed Embodiments

[0019] Reference will now be provided in detail to embodiments of the present application, one or more examples of which are described below. Each example is provided by way of explanation and not limitation of the present application. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the scope or spirit of the present application. For example, features illustrated or described as part of one embodiment can be used in another embodiment to yield a still further embodiment.

[0020] Accordingly, it is intended that the present application cover such modifications and variations that fall 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. Those of ordinary skill in the art should understand that this discussion is only a description of exemplary embodiments and is not intended to limit the broader aspects of the present application.

[0021] In this application, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open technical solution containing the listed features.

[0022] In this application, regarding numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous, and include the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, these 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.

[0023] If there is no special indication, all embodiments and optional embodiments of this application can be combined with each other to form new technical solutions.

[0024] If there is no special indication, all technical features and optional technical features of this application can be combined with each other to form new technical solutions.

[0025] If there is no special indication, all steps of this application can be carried out sequentially or randomly, and preferably sequentially. For example, the method includes steps (a) and (b), which means the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b) and (c), or can also include steps (a), (c) and (b), or can also include steps (c), (a) and (b), etc.

[0026] If there is no special indication, the "including" and "comprising" mentioned in this application represent open-ended, and can also be closed-ended. For example, the "including" and "comprising" can mean that other components not listed can also be included or comprised, or can only include or comprise the listed components.

[0027] If there is no special indication, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) while B is true (or exists); or both A and B are true (or exist).

[0028] A first aspect of the present application provides a solution for a perovskite-based film, the perovskite-based film comprising a compound of the general formula ABX3, where A represents an organic amine cation or an inorganic cation, B represents a metal cation, and X represents a halide ion or an anion of a pseudohalogen. The solution comprises an etchant and a main passivator. The etchant is used to etch the surface of the perovskite-based film so that a BX2 compound is precipitated on the surface of the perovskite-based film. The main passivator is used to react with the BX2 compound to form a two-dimensional perovskite layer on the surface of the perovskite-based film.

[0029] The solution provided by the present application, through the synergistic effect of the etchant and the main passivator, selectively etches the surface of the perovskite-based film by using the etchant so that a BX2 compound is precipitated on its surface, and uses the main passivator to react in situ with BX2 to form a two-dimensional perovskite passivation layer, which can passivate the defects on the surface of the perovskite-based film, reduce non-radiative recombination, and reduce the interfacial energy level mismatch, thereby promoting carrier extraction and improving device performance. Further, by using the solution provided by the present application, on the one hand, there is no need to select a specific passivator for different perovskite formulations, which has better generality and reproducibility, can adapt to a variety of perovskite formulations, and avoids the problem of poor passivation effect caused by formulation differences; on the other hand, it can form a uniform two-dimensional perovskite passivation layer, realizing uniform and effective passivation of the surface of a large-area perovskite-based film, avoiding the problems of uneven passivator concentration in traditional solution-based interface passivation and difficult control of the passivation layer thickness in traditional dry-process interface passivation, improving the passivation efficiency, and at the same time enabling low-cost and highly reproducible product wafering in the production line, and improving the error tolerance rate in the surface passivation process.

[0030] Exemplarily, in the ABX3 compound, A includes FA + , MA + , Cs + , Rb + and K + or one or more of them, B includes Pb 2+ and Sn 2+ or one or more of them, and X is I - .

[0031] In some of these embodiments, the etchant includes an A-site etchant, which is used to etch A-site cations. The A-site etchant includes at least one of isopropyl alcohol, trifluoroethanol, and n-butanol. Thus, the A-site etchant selectively etches A-site cations, thereby exposing the BX2 compound on the surface of the perovskite-based film, and then reacting with the passivator to form a uniform two-dimensional perovskite passivation layer on the surface of the base film, uniformly and effectively passivating the surface of the perovskite-based film. At the same time, the A-site etchant avoids excessive damage to the main structure of the perovskite. Compared with traditional strongly polar solvents, these A-site etchants selectively dissolve A-site cations while maximizing the integrity of the perovskite structure, thus ensuring the performance of the device.

[0032] In some of these embodiments, the etchant further includes a B-site complexing agent, which is used to complex B-site cations. The B-site complexing agent includes at least one of dimethyl sulfoxide, N-methylpyrrolidone, and 1,3-dimethyl-3,4,5,6-tetrahydro-2-pyrimidinone. Thus, for a perovskite thin film with enriched BX2 compounds on the surface, by adding a small amount of the B-site complexing agent, the B-site complexing agent complexes B-site cations, which can remove the surface-enriched BX2 compounds, so that the deeper part of the BX2 compound block that is difficult to be passivated by the passivator is dissolved, and thus can react with the main passivator to form a two-dimensional perovskite passivation layer; therefore, the versatility of the solution is improved, and it is applicable to perovskite thin films with different surface states.

[0033] In some of these embodiments, the volume percentage of the B-site complexing agent in the etchant is 0.01% - 1%. Exemplarily, the volume percentage of the B-site complexing agent in the etchant can be, but is not limited to, 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%. Within the above volume percentage range, the etching process on the surface of the perovskite thin film is controllable, so that the B-site complexing agent can not only remove the overly enriched BX2 compounds, but also cooperate with the main passivator to form a uniform two-dimensional perovskite passivation layer on the surface of the base film, improving the passivation effect.

[0034] In some of these embodiments, the main passivator has a spacer cation, and the spacer cation includes at least one of ethylenediamine cation, benzylamine cation, phenethylamine cation, 4-trifluoromethylphenethylamine cation, propanediamine cation, and piperazine cation. Thus, the introduction of the organic spacer cation can form an effective coordination interaction with the surface-exposed BX2 compounds, and serve as the backbone of the two-dimensional perovskite structure, regulating the interlayer distance of the inorganic layer, optimizing the energy band structure, and promoting charge transport.

[0035] Exemplarily, the main passivator includes at least one of ethylenediamine dihydroiodide, benzylamine hydroiodide, phenethylamine hydroiodide, 4-trifluoromethylphenethylamine hydrochloride, propanediamine dihydroiodide, and piperazine monohydroiodide.

[0036] In some embodiments, the concentration of the main passivator is 0.001 mg / mL to 0.5 mg / mL. Exemplarily, the concentration of the main passivator can be, but is not limited to, 0.001 mg / mL, 0.005 mg / mL, 0.025 mg / mL, 0.05 mg / mL, 0.1 mg / mL, 0.15 mg / mL, 0.2 mg / mL, 0.25 mg / mL, 0.3 mg / mL, 0.35 mg / mL, 0.4 mg / mL, 0.45 mg / mL, 0.5 mg / mL.

[0037] In some embodiments, the solution further includes a co-passivator, and the co-passivator is selected from at least one of methylamine hydroiodide, formamidine hydroiodide, methylamine hydrobromide, and formamidine hydrobromide. Thus, by using the above co-passivator, a synergistic effect can be formed with the main passivator to further fill the vacancy defects on the perovskite surface and optimize the microstructure of the two-dimensional perovskite passivation layer, thereby improving the passivation effect.

[0038] In some embodiments, the concentration of the co-passivator is 0.001 mg / mL to 5 mg / mL. Exemplarily, the concentration of the co-passivator can be, but is not limited to, 0.001 mg / mL, 0.05 mg / mL, 0.1 mg / mL, 0.5 mg / mL, 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL, 3 mg / mL, 3.5 mg / mL, 4 mg / mL, 4.5 mg / mL, 5 mg / mL.

[0039] In some embodiments, the solution further includes a buffer, and the buffer is selected from at least one of toluene, ethyl acetate, diethyl ether, chlorobenzene, and acetone. Thus, by using the above buffer, the etching rate of the etchant can be effectively reduced, avoiding excessive dissolution of the perovskite material by the A-site etchant and ensuring the integrity of the perovskite main structure, thereby maintaining the carrier transport ability of the device; in addition, the use of the buffer makes the etching process more gentle and controllable, which is beneficial to forming a more uniform two-dimensional perovskite passivation layer on the perovskite surface, improving the passivation effect and device performance.

[0040] In some embodiments, the volume ratio of the etchant to the buffer is 1:1 to 1:5. Exemplarily, the volume ratio of the etchant to the buffer can be, but is not limited to, 1:1, 1:2, 1:3, 1:4, 1:5. Further, the volume ratio of the etchant to the buffer is 1:4.

[0041] The second aspect of the present application provides a method for preparing a perovskite thin film. The preparation method includes the following steps: soaking a perovskite base film with the solution provided in the first aspect above to form a two-dimensional perovskite layer on the surface of the perovskite base film, thereby obtaining a perovskite thin film.

[0042] The method for preparing a perovskite thin film provided by the present application can in-situ form a uniform and dense two-dimensional perovskite passivation layer on the surface of the perovskite by soaking the perovskite base film with the solution provided in the first aspect above, thereby effectively passivating surface defects, reducing non-radiative recombination, improving the photoelectric conversion efficiency and stability of the device, and being able to efficiently prepare high-performance perovskite thin films. At the same time, it avoids the performance differences caused by process fluctuations in traditional preparation methods, thereby improving the stability and controllability of the process, helping to improve the yield of perovskite thin films, integrating the etching and passivation steps into the soaking process, simplifying the preparation process, and reducing the production cost.

[0043] In some embodiments, soaking a perovskite base film with the solution provided in the first aspect above to form a two-dimensional perovskite layer on the surface of the perovskite base film, thereby obtaining a perovskite thin film, specifically includes the following steps: S1. Putting the perovskite base film into the solution provided in the first aspect above for soaking treatment to obtain a perovskite thin film precursor. S2. Drying the surface of the perovskite thin film precursor with an inert gas. S3. Annealing the perovskite thin film precursor to obtain a perovskite thin film.

[0044] In some embodiments, in step S1, the soaking time is 1 s to 200 s.

[0045] In some embodiments, in step S2, the inert gas is nitrogen or argon.

[0046] In some embodiments, in step S3, the annealing temperature is 80°C to 150°C, and the time is 1 min to 20 min.

[0047] In some embodiments, after step S1 or step S2, the following steps are further included: putting the perovskite thin film precursor into a cleaning solution for soaking treatment. Among them, the cleaning solution includes an etchant. Further, the cleaning solution also includes a buffer.

[0048] The third aspect of the present application provides a perovskite thin film. The perovskite thin film is prepared by using the method for preparing a perovskite thin film provided in the second aspect above. The perovskite thin film includes a perovskite base film and a two-dimensional perovskite layer, and the two-dimensional perovskite layer is disposed on the surface of the perovskite base film.

[0049] The fourth aspect of the present application provides a solar cell, which includes a perovskite thin film prepared by using the method for preparing a perovskite thin film provided in the second aspect above or the perovskite thin film provided in the third aspect above.

[0050] The present application does not limit the specific structure of the solar cell; in a specific embodiment, the solar cell includes 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.

[0051] In some of these embodiments, the solar cell is an organic solar cell.

[0052] In some of these embodiments, the solar cell is a tandem solar cell. The solar cell further includes a substrate, and a hole transport layer is disposed on the substrate.

[0053] Generally speaking, a tandem solar cell sequentially includes a substrate, a hole transport layer, a perovskite layer, an electron transport layer, and an electrode layer in terms of structure; that is, incident light sequentially passes through the substrate, the hole transport layer, the perovskite layer, the electron transport layer, and the electrode layer.

[0054] In some of these embodiments, the substrate is selected from one of a crystalline silicon cell, a conductive glass, and a flexible conductive film.

[0055] In some of these embodiments, the crystalline silicon cell includes one of a passivated emitter and rear cell (PERC cell), a tunnel oxide passivated contact cell (TOPCon cell), a crystalline silicon heterojunction solar cell (HJT cell), and an interdigitated back contact cell (IBC cell).

[0056] In some of these embodiments, the conductive glass has a certain transparency. The conductive glass generally consists of a glass substrate and an oxide thin film (abbreviated as TCO) conductive layer. 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), and indium zinc oxide (IZO). The conductive glass is generally any conductive glass used in the art. The conductive glass can be commercially obtained. The conductive glass needs to be cleaned before use, for example, ultrasonically cleaned with a cleaning agent, deionized water, ethanol, etc.

[0057] In some of these embodiments, the flexible conductive film includes 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.

[0058] The solar cell provided by the present application can be but is not limited to being used in electric devices such as vehicles, ships, or aircraft.

[0059] One embodiment of the present application provides an electrical device, which may be, but is not limited to, a mobile phone, a tablet computer, a laptop computer, an electric toy, an electric tool, a battery car, an electric vehicle, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, such as a game console, an electric vehicle toy, an electric ship toy, an electric aircraft toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, a spaceship, etc.

[0060] The present application will be further described below in conjunction with specific embodiments and comparative examples.

[0061] For those not specifying specific techniques or conditions in the examples, they shall be carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. For those reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0062] Example 1

[0063] Solution: The solution includes an etchant, a main passivator, an auxiliary passivator, and a buffer. The etchant is a mixed solution of an A-site etchant isopropanol and a B-site complexing agent dimethyl sulfoxide; the main passivator is ethylenediamine dihydroiodide; the auxiliary passivator is methylamine hydroiodide; the buffer is toluene. Among them, the concentration of the main passivator is 0.025 mg / mL, the concentration of the auxiliary passivator is 0.1 mg / mL; the volume percentage of the B-site complexing agent in the etchant is 0.05%; the volume ratio of the etchant to the buffer is 1:4.

[0064] Perovskite film: The perovskite film includes a perovskite base film and a two-dimensional perovskite layer disposed on the perovskite base film.

[0065] (1) Immerse the perovskite base film in the above solution for 30 s to obtain a perovskite film precursor. Among them, the perovskite base film includes FAPbI3.

[0066] (2) Dry the surface of the perovskite film precursor with an inert gas N2.

[0067] (3) Immerse the perovskite film precursor in a cleaning solution for 10 s.

[0068] Among them, the cleaning solution includes an etchant and a buffer. The etchant is a mixed solution of an A-site etchant isopropanol and a B-site complexing agent dimethyl sulfoxide; the buffer is toluene. Among them, the volume percentage of dimethyl sulfoxide as the B-site complexing agent in the etchant is 0.8%; the volume ratio of the etchant to the buffer is 1:4.

[0069] (4) Dry the surface of the perovskite film precursor with an inert gas N2 again.

[0070] (5) The perovskite thin film precursor was annealed at 100 °C for 5 min to obtain a passivated perovskite thin film.

[0071] Solar cell: The solar cell is a reverse perovskite solar cell.

[0072] (1) First, a hole transport layer (Me-4PACz) and a perovskite base film (FA 0.8 MA 0.15 Cs 0.05 Pb(I 0.76 Br 0.24 )3 material) were successively prepared on a substrate (ITO conductive glass).

[0073] (2) The perovskite base film was passivated by using the above preparation method of the perovskite thin film to form a two-dimensional perovskite passivation layer, and a perovskite thin film was obtained.

[0074] (3) An electron transport layer (C 60 material), a buffer layer (BCP), and an electrode layer (Ag metal) were successively prepared on the perovskite thin film to obtain a solar cell.

[0075] Figure 1 This is the SEM test chart of the perovskite thin film provided in this example. As Figure 1 shown, after the perovskite base film was soaked, the grain boundaries on the surface of the obtained perovskite thin film were filled, the grains on the surface were more uniform and dense, and the defects were reduced.

[0076] Figure 2 This is the PL test chart of the perovskite thin film provided in this example. As Figure 2 shown, after the perovskite base film was soaked, the PL brightness was significantly enhanced, indicating that this passivation method had little effect on the bulk perovskite material, and the surface defects were effectively passivated, which could enhance the carrier diffusion length and was beneficial to the extraction and transport of carriers in the device.

[0077] Example 2

[0078] The preparation methods of the solution, perovskite thin film, and solar cell provided in this example are basically the same as those in Example 1, except that the etchant is a mixed solution of the A-site etchant trifluoroethanol and the B-site complexing agent N-methylpyrrolidone.

[0079] Example 3

[0080] The preparation methods of the solution, perovskite thin film, and solar cell provided in this example are basically the same as those in Example 1, except that the etchant is a mixed solution of the A-site etchant n-butanol and the B-site complexing agent 1,3-dimethyl-3,4,5,6-tetrahydro-2-pyrimidinone.

[0081] Example 4

[0082] The preparation methods of the solution, perovskite thin film, and solar cell provided in this example are basically the same as those in Example 1, except that: the volume percentage of the B-site ligand in the etchant is 0.01%.

[0083] Example 5

[0084] The preparation methods of the solution, perovskite thin film, and solar cell provided in this example are basically the same as those in Example 1, except that: the volume percentage of the B-site ligand in the etchant is 1%.

[0085] Example 6

[0086] The preparation methods of the solution, perovskite thin film, and solar cell provided in this example are basically the same as those in Example 1, except that: the volume percentage of the B-site ligand in the etchant is 3%.

[0087] Example 7

[0088] The preparation methods of the solution, perovskite thin film, and solar cell provided in this example are basically the same as those in Example 1, except that: the main passivator is benzylamine hydroiodide.

[0089] Example 8

[0090] The preparation methods of the solution, perovskite thin film, and solar cell provided in this example are basically the same as those in Example 1, except that: the main passivator is 4-trifluoromethylphenethylamine hydrochloride.

[0091] Example 9

[0092] The preparation methods of the solution, perovskite thin film, and solar cell provided in this example are basically the same as those in Example 1, except that: the main passivator is piperazine mono-hydroiodide.

[0093] Example 10

[0094] The preparation methods of the solution, perovskite thin film, and solar cell provided in this example are basically the same as those in Example 1, except that: the etchant is the A-site etchant isopropyl alcohol and does not have a B-site ligand.

[0095] Example 11

[0096] The preparation methods of the solution, perovskite thin film, and solar cell provided in this example are basically the same as those in Example 1, except that: the solution does not have a co-passivator.

[0097] Example 12

[0098] The preparation methods of the solution, perovskite thin film, and solar cell provided in this embodiment are basically the same as those in Example 1, except that: the solution does not have a buffer agent.

[0099] Comparative Example 1

[0100] The preparation methods of the solution, perovskite thin film, and solar cell provided in this comparative example are basically the same as those in Example 1, except that: the solution includes a passivating agent and a solvent. The passivating agent is methylammonium hydroiodide; the solvent is a mixed solvent of isopropyl alcohol and toluene with a volume ratio of 1:4. Among them, the concentration of the passivating agent is 0.1 mg / mL.

[0101] Comparative Example 2

[0102] The preparation methods of the solution, perovskite thin film, and solar cell provided in this comparative example are basically the same as those in Example 1, except that: the solution includes a main passivating agent, an auxiliary passivating agent, and a solvent. The main passivating agent is ethylenediamine dihydroiodide; the auxiliary passivating agent is methylammonium hydroiodide; the solvent is toluene. Among them, the concentration of the main passivating agent is 0.025 mg / mL, and the concentration of the auxiliary passivating agent is 0.1 mg / mL; the volume percentage of the B-site ligand in the etchant is 0.05%.

[0103] Comparative Example 3

[0104] The preparation methods of the solution, perovskite thin film, and solar cell provided in this comparative example are basically the same as those in Example 1, except that: the solution includes an etchant, a main passivating agent, an auxiliary passivating agent, and a buffer agent. The etchant is a mixed solution of the A-site etchant isopropyl alcohol and the B-site ligand dimethyl sulfoxide; the main passivating agent is octadecylamine hydroiodide; the auxiliary passivating agent is methylammonium hydroiodide; the buffer agent is toluene. Among them, the concentration of the main passivating agent is 0.025 mg / mL, and the concentration of the auxiliary passivating agent is 0.1 mg / mL; the volume percentage of the B-site ligand in the etchant is 0.05%; the volume ratio of the etchant to the buffer agent is 1:4.

[0105] Performance Test

[0106] Place the solar cells prepared in the above examples and comparative examples in a solar simulator (manufacturer: Wavelabs), under the irradiation of one sun intensity, apply a bias voltage (Vp, the bias voltage range is -0.1 to 1.3 V) to the device with a test source meter and measure the output current of the device to obtain the bias voltage - current density curve.

[0107] Open-circuit voltage (Voc): The terminal voltage when the cell is not connected to a load, that is, the bias voltage value when the current density in the bias voltage - current density curve is 0 mA·cm -2 at this time.

[0108] Short - circuit current density (Jsc): The output current when the solar cell is short - circuited per unit area, that is, the current density when the bias voltage is 0 V in the bias - current density curve.

[0109] Fill factor (FF): FF = max(Vp×Jsc), where Vp is the bias voltage and Jsc is the short - circuit current density.

[0110] Photovoltaic cell efficiency (PCE): PCE = Voc×Jsc×FF.

[0111] The test results of the above - mentioned performances are shown in Table 1.

[0112] Table 1

[0113] Voc (V) <![CDATA[Jsc (mA·cm -2 )]]> FF (%) PCE (%) Example 1 1.28 21.06 84.39 22.75 Example 2 1.27 20.88 83.23 22.07 Example 3 1.26 20.93 83.56 22.03 Example 4 1.28 20.07 81.40 20.91 Example 5 1.27 19.96 79.42 20.13 Example 6 1.10 18.23 69.34 13.90 Example 7 1.25 20.79 80.77 20.99 Example 8 1.26 20.72 82.11 21.43 Example 9 1.26 20.87 82.39 21.67 Example 10 1.24 20.33 82.25 20.73 Example 11 1.26 19.95 80.21 20.16 Example 12 1.26 19.50 76.30 18.74 Comparative Example 1 1.11 20.81 72.15 16.67 Comparative Example 2 1.12 20.79 72.54 16.89 Comparative Example 3 1.04 17.51 43.98 8.00

[0114] As shown in Table 1, by comparing Examples 1 - 12 and Comparative Examples 1 - 3, it can be seen that the solution provided by this application can passivate the defects on the surface of the perovskite - based film, thereby promoting carrier extraction and improving the device performance of the solar cell.

[0115] The technical features of the above - mentioned embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above - mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0116] The above - mentioned embodiments only represent several implementation manners of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the patent scope of this application. It should be noted that for those of ordinary skill in the art, without departing from the technical concept of this application, several deformations and improvements can still be made, and these all belong to the protection scope of this application. Therefore, the protection scope of this application should be subject to the appended claims.

Claims

1. A solution, characterized in that, For a perovskite-based film, the perovskite-based film comprises a compound of the general formula ABX3, wherein A represents an organic amine cation or an inorganic cation, B represents a metal cation, and X represents a halide ion or an anion of a pseudohalogen. The solution comprises: An etchant for etching the surface of the perovskite-based film so that a BX2 compound is precipitated on the surface of the perovskite-based film; and A main passivator for reacting with the BX2 compound to form a two-dimensional perovskite layer on the surface of the perovskite-based film.

2. The solution according to claim 1, wherein The etchant comprises an A-site etchant for etching the A-site cation, and the A-site etchant comprises at least one of isopropyl alcohol, trifluoroethanol, and n-butanol.

3. The solution according to claim 2, characterized in that, The etchant further comprises a B-site complexing agent for complexing the B-site cation, and the B-site complexing agent comprises at least one of dimethyl sulfoxide, N-methylpyrrolidone, and 1,3-dimethyl-3,4,5,6-tetrahydro-2-pyrimidinone.

4. The solution according to claim 3, wherein The volume percentage of the B-site complexing agent in the etchant is 0.01% to 1%.

5. The solution according to any one of claims 1 to 4, characterized in that, The main passivator has a spacer cation, and the spacer cation comprises at least one of an ethylenediamine cation, a benzylamine cation, a phenethylamine cation, a 4-trifluoromethylphenethylamine cation, a propanediamine cation, and a piperazine cation.

6. The solution according to any one of claims 1 to 4, characterized in that, The solution further comprises: An auxiliary passivator selected from at least one of methylammonium hydroiodide, formamidinium hydroiodide, methylammonium hydrobromide, and formamidinium hydrobromide.

7. The solution according to any one of claims 1 to 4, characterized in that, The solution further comprises: A buffer selected from at least one of toluene, ethyl acetate, diethyl ether, chlorobenzene, and acetone.

8. A method for preparing a perovskite thin film, characterized in that, Comprising the following steps: Soaking the perovskite-based film with the solution according to any one of claims 1 to 7 to form a two-dimensional perovskite layer on the surface of the perovskite-based film, thereby obtaining a perovskite thin film.

9. A perovskite thin film, characterized in that, Prepared by using the method for preparing a perovskite thin film according to claim 8, the perovskite thin film comprises: A perovskite-based film; and A two-dimensional perovskite layer disposed on the surface of the perovskite-based film.

10. A solar cell, characterized in that, Comprising a perovskite thin film prepared by using the method for preparing a perovskite thin film according to claim 8 or the perovskite thin film according to claim 9.

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