Perovskite layer and preparation method therefor, solar cell, and photovoltaic module

Abstract

Disclosed are a perovskite layer and a preparation method therefor, a solar cell, and a photovoltaic module. The preparation method for a perovskite layer comprises: preparing a metal halide framework layer; fumigating the metal halide framework layer by using the steam of a framework layer bulking agent; and coating an organic cation solution onto the fumigated metal halide framework layer to prepare a perovskite layer, wherein the framework layer bulking agent is a dimethyl sulfoxide solvent and / or an N,N-dimethyl formamide solvent.

Description

Perovskite layer and preparation method thereof, solar cell, and photovoltaic module

[0001] The present invention claims priority to the Chinese patent application filed with the Patent Office of China on September 11, 2023, with application number 202311167317.X and invention name “Perovskite layer and preparation method thereof, solar cell, photovoltaic module”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention relates to the field of photovoltaic technology, and in particular to a perovskite layer and a preparation method thereof, a solar cell, and a photovoltaic module. Background Art

[0003] Perovskite cells are solar cells that use a thin film of a perovskite-type organic metal halide semiconductor as the light-absorbing material. They can be used alone or as a tandem solar cell, combining a wide-bandgap top cell with a narrow-bandgap bottom cell in series. Existing perovskite cells or tandem cells typically use a two-step process to prepare the perovskite layer. First, a metal halide is pre-prepared on a substrate (using methods such as spin coating and evaporation) to form a metal halide skeleton layer. An organic cation solution is then applied to the metal halide skeleton layer, where it reacts with the metal halide to form the perovskite layer. Spin coating is generally used for preparing the metal halide skeleton layer on small-area devices; using it on large-area devices can easily lead to uneven coating. Metal halide skeleton layers prepared by evaporation are too dense, making it difficult for the organic cation solution to penetrate the bottom of the metal halide skeleton layer and react with the metal halide within. This hinders the subsequent formation of the perovskite layer and can result in metal halide residue.

[0004] Therefore, seeking a method that can not only solve the problem of excessive density of the skeleton layer in the existing perovskite layer preparation process, but also improve the utilization rate of metal halides and be suitable for mass production applications is a technical problem that needs to be solved in this field.

[0005] Summary of the Invention

[0006] The embodiments of the present application disclose a perovskite layer and a preparation method thereof, a solar cell, and a photovoltaic module to solve the problems in the prior art of solar cells caused by the perovskite layer manufacturing process, such as excessive density of the skeleton layer, low utilization rate of metal halide, and difficulty in mass production.

[0007] To achieve the above objectives, in a first aspect, embodiments of the present application provide a method for preparing a perovskite layer, the method comprising the following steps:

[0008] preparing a metal halide skeleton layer;

[0009] The metal halide skeleton layer is treated by fumigation with steam of a skeleton layer loosening agent; wherein the skeleton layer loosening agent is a dimethyl sulfoxide solvent and / or an N,N-dimethylformamide solvent;

[0010] coating an organic cation solution on the metal halide skeleton layer after fumigation to prepare a perovskite layer;

[0011] Post-processing is performed on the perovskite layer to obtain the solar cell.

[0012] Furthermore, the step of using steam fumigation of the skeleton layer loosening agent to treat the metal halide skeleton layer is:

[0013] Evenly coating the skeleton layer loosening agent on the bottom edge of the container;

[0014] Heating the container so that the steam of the skeleton layer loosening agent is distributed in the interior space of the container;

[0015] The substrate having the metal halide skeleton layer formed thereon is placed in the container and fumigated in the steam of the skeleton layer loosening agent.

[0016] Furthermore, in the step of heating the container to distribute the steam of the skeleton layer loosening agent in the inner space of the container, the heating time is 15 minutes to 30 minutes and the heating temperature is 60° C. to 80° C.

[0017] Furthermore, in the step of placing the substrate formed with the metal halide skeleton layer in the container and fumigating it in the steam of the skeleton layer loosening agent, the fumigation time is 30 seconds to 10 minutes.

[0018] Furthermore, in the step of treating the metal halide skeleton layer with the steam fumigation of the skeleton layer loosening agent, the volume concentration of the skeleton layer loosening agent in the container is 2.83×10 -2 μL / cm 3 ~4.72×10 -2 μL / cm 3 .

[0019] Furthermore, the material of the perovskite layer has a rod-like structure.

[0020] Furthermore, the step of preparing the metal halide skeleton layer is: evaporating metal halide on the substrate having a suede structure to form the metal halide skeleton layer.

[0021] Furthermore, the metal halide is one or more of lead halide, cesium halide and rubidium halide.

[0022] Furthermore, in the step of preparing the metal halide skeleton layer, PbI2 and CsBr in a molar ratio of 5:1 to 10:1 are co-evaporated on the substrate to form the metal halide skeleton layer.

[0023] Furthermore, the thickness of the metal halide skeleton layer is 300 nm to 400 nm.

[0024] Furthermore, the step of coating the organic cation solution on the metal halide skeleton layer after fumigation to prepare the perovskite layer is:

[0025] Spin coating the organic cation solution on the fumigated metal halide skeleton layer;

[0026] Annealing is performed after spin coating.

[0027] Furthermore, the spin coating speed of the organic cationic solution is 3500 rpm to 4500 rpm, the spin coating acceleration is 3500 rpm / s to 4500 rpm / s, and the spin coating time is 20s to 40s.

[0028] Furthermore, the annealing temperature is 100°C to 150°C.

[0029] Furthermore, the annealing time is 20 min to 40 min. Furthermore, the organic cation solution consists of FAI, MABr, and MACl.

[0030] Furthermore, the concentration of the organic cation solution is 80 mg / mL to 100 mg / mL.

[0031] Furthermore, the amount of the organic cation solution used is 80 μL to 130 μL.

[0032] In a second aspect, an embodiment of the present application provides a perovskite layer, which is prepared by the preparation method of the perovskite layer as described in the first aspect.

[0033] In a third aspect, an embodiment of the present application provides a solar cell, wherein the solar cell includes a perovskite layer prepared by the method for preparing a perovskite layer as described in the first aspect, or the solar cell includes the perovskite layer as described in the second aspect.

[0034] In a fourth aspect, an embodiment of the present application provides a photovoltaic module, which includes the solar cell as described in the third aspect.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The preparation method of the perovskite layer provided in the embodiment of the present application uses a specific reagent dimethyl sulfoxide solvent or N,N-dimethylformamide solvent as a skeleton layer loosening agent during the preparation process, and the skeleton layer loosening agent is used to fumigate the metal halide skeleton layer in the form of steam gas. This practice can cause micropores to appear in the originally dense metal halide skeleton layer and become loose, thereby solving the problem of excessive density of the metal halide skeleton layer in the process of preparing the perovskite layer in the prior art. On the basis of the fumigation treatment, since the metal halide skeleton layer becomes relatively loose, when the organic cation solution is subsequently coated on the metal halide skeleton layer for reaction to prepare the perovskite layer, it is easier to penetrate into the middle of the metal halide skeleton layer and react with the bottom, forming a better perovskite structure and effectively reducing the metal halide residue at the bottom of the perovskite layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, a brief introduction will be given below to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] FIG1 is a schematic flow chart of a method for preparing a perovskite layer according to Example 1 of the present application;

[0039] FIG2 is a scanning electron microscope image of the metal halide skeleton layer before fumigation treatment during the formation of the perovskite layer in Example 13;

[0040] FIG3 is a scanning electron microscope image of the metal halide skeleton layer after fumigation treatment in the process of forming the perovskite layer in Example 13;

[0041] FIG4 is a scanning electron microscope image of a metal halide skeleton layer that has not been fumigated during the formation of a perovskite layer in Comparative Example 1;

[0042] FIG5 is a scanning electron microscope image of the metal halide skeleton layer after fumigation treatment during the formation of the perovskite layer in Example 1;

[0043] FIG6 is a scanning electron microscope image of the perovskite layer of Comparative Example 1;

[0044] FIG7 is a scanning electron microscope image of the perovskite layer of Example 1;

[0045] FIG8 is a scanning electron microscope image of the metal halide skeleton layer at different fumigation times. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0047] In the present invention, terms such as "upper," "lower," "left," "right," "front," "back," "top," "bottom," "inner," "outer," "center," "vertical," "horizontal," "transverse," and "longitudinal" indicate positions or locations based on the positions or locations shown in the accompanying drawings. These terms are primarily intended to better describe the present invention and its embodiments and are not intended to limit the devices, elements, or components indicated to having a specific orientation, or to being constructed or operated in a specific orientation.

[0048] Furthermore, some of the above terms may be used to express other meanings besides indicating a position or location. For example, the term "on" may also be used to indicate a dependency or connection in certain circumstances. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0049] Furthermore, the terms "installed," "disposed," "provided with," "connected," and "connected" should be interpreted broadly. For example, they can refer to fixed connections, removable connections, or integral structures; mechanical connections or electrical connections; direct connections or indirect connections through an intermediary; or internal communication between two devices, elements, or components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on specific circumstances.

[0050] Furthermore, the terms "first," "second," etc., are primarily used to distinguish between different devices, elements, or components (which may or may not be of the same type and configuration), and are not intended to indicate or imply the relative importance or quantity of the devices, elements, or components indicated. Unless otherwise specified, "plurality" means two or more.

[0051] The technical solution provided by the present invention will be further described below with reference to the embodiments and drawings.

[0052] The preparation of existing perovskite layers typically uses a two-step process: first, a metal halide is pre-prepared on a substrate (including spin coating and evaporation methods) to form a metal halide skeleton layer, and then an organic cation solution is coated on the metal halide skeleton layer to react with the metal halide to form a perovskite layer. Currently, evaporation is the most commonly used method for preparing the metal halide skeleton layer. However, the metal halide skeleton layer prepared by evaporation is too dense, making it difficult for the organic cation solution to penetrate the bottom of the metal halide skeleton layer and react with the metal halide inside, which is not conducive to the subsequent formation of the perovskite layer and will produce metal halide residue. The use of spin coating is generally limited to small-area solar cell devices. This is because spin coating on large-area solar cell devices can easily lead to uneven coating, making it difficult to meet large-scale mass production requirements. In addition, the metal halide skeleton layer prepared by spin coating is prone to the problem of film structure becoming dense over time. This high density of the film layer can lead to problems such as incomplete subsequent reactions and reactant residue.

[0053] Based on the above analysis, the embodiments of the present application provide a perovskite layer and a preparation method thereof, a solar cell, and a photovoltaic module to solve the problems in the existing perovskite layer preparation process, such as excessive density of the metal halide skeleton layer, low metal halide utilization, reactant residue, and difficulty in adapting to mass production requirements.

[0054] In a first aspect, an embodiment of the present application provides a method for preparing a perovskite layer, the preparation method comprising the following steps:

[0055] preparing a metal halide skeleton layer;

[0056] The metal halide skeleton layer is treated by fumigation with steam of a skeleton layer loosening agent; wherein the skeleton layer loosening agent is a dimethyl sulfoxide solvent or an N,N-dimethylformamide solvent;

[0057] coating an organic cation solution on the metal halide skeleton layer after fumigation to prepare a perovskite layer;

[0058] Post-processing is performed on the perovskite layer to obtain the solar cell.

[0059] Fumigation treatment refers to a process in which a liquid skeleton layer loosening agent is converted into a vaporous gaseous state by a certain treatment method, and then the metal halide skeleton layer is placed in the skeleton layer loosening agent vapor atmosphere, so that the skeleton layer loosening agent vapor enters the metal halide skeleton layer, causing the two to react or the metal halide to dissolve. In addition, the treatment method may be, for example, heating or pressurizing to convert the liquid into vapor.

[0060] The preparation method of the perovskite layer provided in the embodiment of the present application uses a specific reagent dimethyl sulfoxide solvent or N,N-dimethylformamide solvent as a skeleton layer loosening agent during the preparation process, and the skeleton layer loosening agent is used to fumigate the metal halide skeleton layer in the form of steam gas. This practice can cause micropores to appear in the originally dense metal halide skeleton layer and become loose, thereby solving the problem of excessive density of the metal halide skeleton layer in the process of preparing the perovskite layer in the prior art. On the basis of the fumigation treatment, since the metal halide skeleton layer becomes relatively loose, when the organic cation solution is subsequently coated on the metal halide skeleton layer for reaction to prepare the perovskite layer, it is easier to penetrate into the middle of the metal halide skeleton layer and react with the bottom, forming a better perovskite structure and effectively reducing the metal halide residue at the bottom of the perovskite layer.

[0061] Among them, when the metal halide skeleton layer is fumigated with N,N-dimethylformamide solvent in vapor form, N,N-dimethylformamide can dissolve the metal halide to form micropores, thereby improving the looseness of the metal halide skeleton layer. When the metal halide skeleton layer is fumigated with dimethyl sulfoxide solvent in vapor form, dimethyl sulfoxide not only dissolves the metal halide, but can also react with the metal halide to form a complex intermediate, thereby making the metal halide skeleton layer have a better effect of micropores. Therefore, the skeleton layer loosening agent of the embodiment of the present application can use either N,N-dimethylformamide solvent or dimethyl sulfoxide solvent, preferably dimethyl sulfoxide solvent.

[0062] While immersing the metal halide skeleton layer in an ionic liquid solution or spin-coating the metal halide skeleton layer with an ionic liquid solution can help make the dense metal halide skeleton layer fluffy and porous, these solution methods also have significant drawbacks. For solar cells that require shape preservation, the introduction of the ionic liquid solution can reduce the thickness of the metal halide skeleton layer and cause uneven distribution, which can expose the top of the tower and cause shape problems. Furthermore, incomplete removal of the solution at the bottom of the tower can also result in residual metal halide solution.

[0063] In the embodiment of the present application, the skeleton layer loosening agent is brought into contact with the metal halide skeleton layer in the form of vapor, changing the large-area contact reaction between the solid phase and the liquid phase to a small-area contact reaction between the solid phase and the gas phase. The loosening agent is more uniformly distributed in the metal halide skeleton layer than the solution method, and has less impact on the film thickness of the metal halide skeleton layer. Therefore, on the basis of improving the loosening effect on the metal halide skeleton layer, the shape retention effect of the solar cell can be further ensured.

[0064] Furthermore, the step of using steam fumigation of the skeleton layer loosening agent to treat the metal halide skeleton layer is:

[0065] Evenly coating the skeleton layer loosening agent on the bottom edge of the container;

[0066] Heating the container so that the steam of the skeleton layer loosening agent is distributed in the interior space of the container;

[0067] The substrate having the metal halide skeleton layer formed thereon is placed in the container and fumigated in the steam of the skeleton layer loosening agent.

[0068] It is understood that in the step of fumigating the metal halide skeleton layer with the steam of the skeleton layer loosening agent, the order of heating the container and placing the substrate having the metal halide skeleton layer formed therein is not limited. For example, the container may be heated first so that the vapor of the skeleton layer loosening agent is distributed throughout the interior space of the container; then the substrate having the metal halide skeleton layer formed therein is quickly placed in the container so that the substrate having the metal halide skeleton layer formed therein is fully fumigated and loosened in the vapor of the skeleton layer loosening agent. For another example, the substrate having the metal halide skeleton layer formed therein may be placed in the container first, and then the container may be heated so that the liquid skeleton layer loosening agent is converted into vapor before fumigating the metal halide skeleton layer. In addition, when fumigating the metal halide skeleton layer, it is preferred that the container be sealed to ensure a better fumigation effect.

[0069] Evenly coating the skeleton layer loosening agent on the edge of the bottom surface of the sealed container before fumigation is beneficial to providing a more uniform steam atmosphere and further improving the loosening and pore-forming effect of the skeleton layer loosening agent vapor on the metal halide skeleton layer.

[0070] Furthermore, in the step of heating the container so that the vapor of the skeleton layer loosening agent is distributed in the internal space of the container, the heating time is 15 minutes to 30 minutes, and the heating temperature is 60°C to 80°C. Among them, the heating time of 15 minutes to 30 minutes includes any value within this numerical range, for example, the heating time in this step is 15 minutes, 18 minutes, 20 minutes, 22 minutes, 25 minutes, 28 minutes or 30 minutes. The heating temperature of 60°C to 80°C includes any value within this numerical range, for example, the heating temperature in this step is 60°C, 62°C, 65°C, 68°C, 70°C, 72°C, 75°C, 78°C or 80°C. Under the above heating time and heating temperature conditions, the volatilization of the dimethyl sulfoxide solvent and / or the N,N-dimethylformamide solvent can be accelerated to ensure that the liquid skeleton layer loosening agent in the closed container is fully converted into a gaseous form. In particular, the above temperature conditions can ensure a good steam effect without damaging other structural film layers of the solar cell due to excessive temperature.

[0071] Furthermore, in the step of placing the substrate having the metal halide skeleton layer in the container and fumigating it in the steam of the skeleton layer loosening agent, the fumigation time is 30 seconds to 10 minutes. The fumigation time of 30 seconds to 10 minutes includes any value within the time range, such as a fumigation time of 30 seconds, 60 seconds, 1.5 minutes, 2 minutes, 3 minutes, 5 minutes, 7 minutes, 8 minutes or 10 minutes. After the skeleton layer loosening agent forms a steam atmosphere at 60°C to 80°C, the substrate having the metal halide skeleton layer is placed in the steam atmosphere and fumigated for a period of 30 seconds to 10 minutes, which can better ensure the dissolution and / or complexation reaction of the skeleton layer loosening agent on the metal halide, thereby ensuring a good loosening effect on the metal halide skeleton layer.

[0072] In the embodiment of the present application, the material of the metal halide skeleton layer has a rod-like structure and / or a granular structure under microscopic observation conditions (eg, when observed under a scanning electron microscope). Preferably, the material of the metal halide skeleton layer has a rod-like structure.

[0073] Although the metal halide skeleton layer material has certain loose and porous structural characteristics when its microstructure is granular, when the metal halide skeleton layer material microstructure is a rod-shaped structure, the metal halide skeleton layer as a whole will present a more obvious loose and porous structure, which is better than the loose effect of the granular structure, thereby greatly improving the looseness of the originally dense metal halide skeleton layer.

[0074] In addition, in the step of using the steam fumigation of the skeleton layer loosening agent to treat the metal halide skeleton layer, the volume concentration of the skeleton layer loosening agent in the container is 2.83×10 -2 μL / cm 3 ~4.72×10 -2 μL / cm 3 Among them, the volume concentration of the skeleton layer loosening agent is 2.83×10 -2 μL / cm 3 ~4.72×10 -2 μL / cm 3 Including any point value within this numerical range, for example, the volume concentration of the skeleton layer loosening agent in the container is 2.83×10 -2 μL / cm 3 , 2.85×10 -2 μL / cm 3 , 2.9×10 -2 μL / cm 3 , 3.0×10 -2 μL / cm 3 , 3.2×10 -2 μL / cm3 , 3.5×10 -2 μL / cm 3 , 3.7×10 -2 μL / cm 3 , 3.9×10 -2 μL / cm 3 , 4.0×10 -2 μL / cm 3 , 4.2×10 -2 μL / cm 3 , 4.5×10 -2 μL / cm 3 , 4.6×10 -2 μL / cm 3 or 4.72×10 -2 μL / cm 3 The above volume concentration, in conjunction with the fumigation time, can make the fumigation treatment more effective, allowing a small amount of skeleton layer loosening agent to evenly enter the metal halide skeleton layer to form micropores, thereby achieving a better loose and porous effect. On this basis, after the subsequent organic cations are coated on the surface of the metal halide skeleton layer, they can utilize the micropores formed by the fumigation treatment to penetrate into the middle and bottom of the metal halide skeleton layer, reacting with the metal halide in the middle and bottom, thereby improving the material utilization rate of the metal halide and effectively reducing the residual metal halide.

[0075] Furthermore, the step of preparing the metal halide skeleton layer is: evaporating metal halide on a substrate having a velvet structure to form the metal halide skeleton layer, wherein the metal halide is one or more of lead halide, cesium halide and rubidium halide.

[0076] It is understood that the formed metal halide skeleton layer can be composed of one of lead halide, cesium halide and rubidium halide, or a combination of multiple lead halide, cesium halide and rubidium halide. Metal halide can be used as one of the raw materials of the perovskite layer. Cesium halide and / or rubidium halide are co-evaporated with lead halide to form a metal halide skeleton layer. The band gap of the formed perovskite layer can be adjusted so that the band gap is matched with the bottom cell when the formed perovskite layer is used in a stacked cell. The halogen element in the metal halide can be at least one of iodine, chlorine and bromine, so the metal halide can include at least one of lead iodide, lead chloride, lead bromide, cesium iodide, cesium bromide, cesium chloride and rubidium iodide.

[0077] For solar cells with a velvet structure and shape preservation requirements, if a solution method is used to directly coat the perovskite precursor solution on the velvet structure, it is easy for the solution to flow toward the bottom of the velvet structure, resulting in the top of the tower being exposed and the bottom of the tower being piled up, leading to the problem of uneven coating of the perovskite layer. However, the embodiment of the present application can effectively loosen the metal halide skeleton layer while meeting the requirements of good velvet shape preservation of solar cells, uniform coating of the perovskite layer, and suitability for large-area solar cell production processes. On this basis, the amount of skeleton layer loosening agent used is reduced, the utilization rate of metal halide is improved, the residual metal halide at the bottom of the velvet structure is reduced, and the performance of the perovskite layer is optimized.

[0078] The embodiments of the present application can use different substrates according to the different structures and requirements of the solar cells. For example, if the solar cell is a single-junction cell and does not require shape preservation, a flat transparent conductive substrate can be used. If the solar cell is a perovskite / crystalline silicon tandem cell, a crystalline silicon bottom cell with a velvet structure (e.g., a pyramid-shaped velvet structure) and a composite layer and a hole transport layer located thereon can be used as the substrate.

[0079] Specifically, when a metal halide skeleton layer is formed on a substrate with a velvet structure on the surface by an evaporation process, a dense and uniform skeleton layer can be formed, ensuring a good velvet shape-keeping effect and meeting the process of manufacturing large-area solar cells. For the dense metal halide skeleton layer, fumigation is performed by the steam of the skeleton layer loosening agent. Then, through the complexation reaction and / or dissolution between the solid phase and the gas phase, micropores can be formed in the metal halide skeleton layer when a small amount of skeleton layer loosening agent is used, thereby achieving a loosening treatment of the metal halide skeleton layer. When an organic cationic solution is applied to prepare a perovskite layer on the basis of the loosening of the metal halide skeleton layer, the organic cationic solution reacts more fully with the metal halide through the action of the micropores, especially can penetrate into the bottom of the metal halide skeleton layer to react, thereby increasing the degree of reaction and reducing the residual halide at the bottom. Furthermore, since there is no need to centrifuge the skeleton layer loosening agent, the problem of large-scale loss of metal halide when the skeleton layer loosening agent is centrifuged can also be avoided.

[0080] Furthermore, in the step of preparing the metal halide skeleton layer, PbI2 and CsBr are co-evaporated on the substrate in a molar ratio of 5:1 to 10:1 to form the metal halide skeleton layer with a thickness of 300nm to 400nm. Lead iodide and cesium bromide within this molar ratio range can better regulate the band gap, thereby obtaining a perovskite layer with a wider adjustable band gap range. In addition, the metal halide skeleton layer is controlled within the above-mentioned thickness range. When the organic cation solution is subsequently coated on the metal halide skeleton layer after the fumigation treatment, the metal halide skeleton layer can be directly penetrated by the organic cation solution and fully react with it, thereby avoiding the problem that the existing metal halide skeleton layer is too dense when reacting with the organic cation solution, so that the metal halide inside is difficult to participate in the reaction and remains, so that the final perovskite layer has better film quality.

[0081] Furthermore, the step of coating the organic cation solution on the metal halide skeleton layer after fumigation to prepare the perovskite layer is:

[0082] Spin coating the organic cation solution on the metal halide skeleton layer after fumigation treatment at a spin coating speed of 3500 rpm to 4500 rpm, a spin coating acceleration of 3500 rpm / s to 4500 rpm / s, and a spin coating time of 20 s to 40 s;

[0083] After spin coating, anneal at 100°C to 150°C for 20min to 40min.

[0084] On the one hand, under the above spin coating and annealing conditions, the efficiency of the prepared perovskite layer is the highest. On the other hand, the above annealing conditions not only facilitate the preparation of the perovskite layer, but also volatilize the residual framework layer bulking agent, eliminating the need for additional treatment of the remaining framework layer bulking agent, saving process and avoiding the loss of metal halide.

[0085] Furthermore, the organic cation solution is composed of FAI, MABr, and MACl at a concentration of 80 mg / mL to 100 mg / mL, and is used in a dosage of 80 μL to 130 μL. The composition and concentration of the organic cation solution allow for complete reaction with the metal halide skeleton layer, resulting in the most efficient perovskite layer. FAI refers to iodomethane, MABr refers to methylammonium bromide, and MACl refers to methylammonium chloride.

[0086] In a second aspect, an embodiment of the present application provides a perovskite layer, which is prepared by the preparation method of the perovskite layer as described in the first aspect.

[0087] In a third aspect, an embodiment of the present application further discloses a solar cell, wherein the solar cell includes a perovskite layer prepared by the method for preparing a perovskite layer as described in the first aspect, or the solar cell includes the perovskite layer as described in the second aspect.

[0088] As an optional embodiment, the solar cell is a perovskite tandem cell, i.e., a bottom cell and a perovskite top cell are stacked together to form a composite cell. The substrate includes a bottom cell, a hole recombination layer, and a hole transport layer sequentially disposed on the bottom cell, and the metal halide skeleton layer is formed on the side of the hole transport layer away from the electron-hole recombination layer.

[0089] In addition, the solar cell may further include an electron transport layer, a buffer layer, and an electrode structure located on the surface of the perovskite layer away from the hole transport layer. It will be understood that in this embodiment, the structures and materials of the other layers of the solar cell except the perovskite layer may adopt structures and materials known in the art. For example, the bottom cell, electron-hole recombination layer, hole transport layer, electron transport layer, and electrode may adopt relevant materials and structures known in the art. In addition, those skilled in the art may select any suitable bottom cell in the art according to actual needs, for example, the bottom cell may be a TOPCon bottom cell or an HJT bottom cell.

[0090] As another optional embodiment, the solar cell is a single-junction perovskite cell, meaning the perovskite cell is a standalone, complete cell and is not stacked with a crystalline silicon cell. In this solar cell, the substrate includes a transparent conductive substrate and a hole transport layer disposed on the transparent conductive substrate, and the metal halide skeleton layer is formed on a side of the hole transport layer facing away from the transparent conductive substrate.

[0091] In addition, the solar cell may also include an electron transport layer and electrodes located on the surface of the perovskite layer away from the hole transport layer. It is understood that in this embodiment, the structures and materials of the solar cell layers other than the perovskite layer can adopt structures and materials known in the art. For example, the transparent conductive substrate, hole transport layer, electron transport layer, and electrodes can adopt relevant materials and structures known in the art.

[0092] In a fourth aspect, an embodiment of the present application provides a photovoltaic module, which includes the solar cell as described in the third aspect.

[0093] The technical solution of the present application will be further explained below in conjunction with more specific embodiments and experimental test results.

[0094] Example 1

[0095] This embodiment provides a method for preparing a perovskite layer. FIG1 is a process flow chart of the preparation method of this embodiment. The preparation method includes the following steps:

[0096] Preparation of a metal halide skeleton layer; specifically, placing a substrate having a pyramid velvet structure in an evaporation device, co-evaporating lead iodide (PbI2) and cesium bromide (CsBr), wherein the molar ratio of the lead iodide (PbI2) to the cesium bromide (CsBr) is 8:1, and forming a dense metal halide skeleton layer on the surface of the substrate by co-evaporation; the thickness of the metal halide skeleton layer is 300 nm to 400 nm;

[0097] The metal halide skeleton layer is treated by steam fumigation of the skeleton layer loosening agent; specifically, a volume concentration of 3.77×10 -2 μL / cm 3 dimethyl sulfoxide (DMSO) solvent; heating the container at 70° C. for 20 minutes to evenly distribute the dimethyl sulfoxide vapor in the internal space of the container; placing the substrate containing the metal halide skeleton layer after co-evaporation in the previous step in the container for fumigation for 5 minutes to complete the fumigation;

[0098] An organic cation solution is coated on the metal halide skeleton layer after fumigation to prepare a perovskite layer; specifically, an organic cation solution with a concentration of 90 mg / mL is prepared, and 100 μL of the organic cation solution is coated on the surface of the metal halide skeleton layer after fumigation in the previous step by spin coating, with a spin coating speed of 4000 rpm, an acceleration of 4000 rpm / s, and a spin coating time of 30 s; after spin coating, it is placed on a hot stage at 135°C and annealed for 30 minutes to obtain a perovskite layer; wherein the organic cation solution consists of FAI, MABr, and MACl.

[0099] Example 2

[0100] This embodiment provides a method for preparing a perovskite layer. The only difference between this embodiment and the method for preparing a perovskite layer in the first embodiment is that in the step of using the steam fumigation of the skeleton layer loosening agent to treat the metal halide skeleton layer, the volume concentration of the skeleton layer loosening agent dimethyl sulfoxide is 2.83×10 -2 μL / cm 3 .

[0101] Example 3

[0102] This embodiment provides a method for preparing a perovskite layer. The difference between this embodiment and the method for preparing a perovskite layer in the first embodiment is that in the step of using the steam fumigation of the skeleton layer loosening agent to treat the metal halide skeleton layer, the volume concentration of the skeleton layer loosening agent dimethyl sulfoxide is 4.72×10 -2 μL / cm3 .

[0103] Example 4

[0104] This embodiment provides a method for preparing a perovskite layer. The only difference between this embodiment and the method for preparing a perovskite layer in the first embodiment is that in the step of using the steam fumigation of the skeleton layer loosening agent to treat the metal halide skeleton layer, the volume concentration of the skeleton layer loosening agent dimethyl sulfoxide is 2.0×10 -2 μL / cm 3 .

[0105] Example 5

[0106] This embodiment provides a method for preparing a perovskite layer, which differs from the method for preparing a perovskite layer in Example 1 only in that, in the step of using the steam fumigation of the skeleton layer loosening agent to treat the metal halide skeleton layer, the volume concentration of the skeleton layer loosening agent dimethyl sulfoxide is 5.0×10 -2 μL / cm 3 .

[0107] Example 6

[0108] This embodiment provides a method for preparing a perovskite layer, which differs from the method for preparing a perovskite layer in Example 1 only in that, in the step of fumigating the metal halide skeleton layer with steam of a skeleton layer loosening agent in this embodiment, the fumigation time is 30 seconds.

[0109] Example 7

[0110] This embodiment provides a method for preparing a perovskite layer, which differs from the method for preparing a perovskite layer in Example 1 only in that, in the step of fumigating the metal halide skeleton layer with steam of a skeleton layer loosening agent in this embodiment, the fumigation time is 1 minute.

[0111] Example 8

[0112] This embodiment provides a method for preparing a perovskite layer, which differs from the method for preparing a perovskite layer in Example 1 only in that, in the step of fumigating the metal halide skeleton layer with steam of a skeleton layer loosening agent in this embodiment, the fumigation time is 3 minutes.

[0113] Example 9

[0114] This embodiment provides a method for preparing a perovskite layer, which differs from the method for preparing a perovskite layer in Example 1 only in that, in the step of fumigating the metal halide skeleton layer with steam of a skeleton layer loosening agent in this embodiment, the fumigation time is 10 minutes.

[0115] Example 10

[0116] This embodiment provides a method for preparing a perovskite layer, which differs from the method for preparing a perovskite layer in Example 1 only in that, in the step of using the steam fumigation of the skeleton layer loosening agent to treat the metal halide skeleton layer, the container is sealed and heated and the fumigation temperature is 80°C.

[0117] Example 11

[0118] This embodiment provides a method for preparing a perovskite layer, which differs from the method for preparing a perovskite layer in Example 1 only in that, in the step of using the steam fumigation of the skeleton layer loosening agent to treat the metal halide skeleton layer, the container is sealed and heated and the fumigation temperature is 60°C.

[0119] Example 12

[0120] This embodiment provides a method for preparing a perovskite layer, which differs from the method for preparing a perovskite layer in Example 1 only in that the skeleton layer loosening agent in this embodiment is N,N-dimethylformamide solvent.

[0121] Example 13

[0122] This embodiment provides a method for preparing a perovskite layer, which differs from the method for preparing a perovskite layer in Example 1 only in that the structure of the substrate is different. The substrate in this embodiment has a planar structure and no velvet structure.

[0123] Comparative Example

[0124] This comparative example provides a method for preparing a perovskite layer, which differs from the method for preparing a perovskite layer in Example 1 only in that this comparative example does not perform the step of steam fumigation treatment of the metal halide skeleton layer using a skeleton layer loosening agent. Instead, after forming a metal halide skeleton layer on a substrate by co-evaporation, an organic cation solution is directly coated on the fumigated metal halide skeleton layer to prepare the perovskite layer.

[0125] Performance Testing

[0126] First, referring to Figures 2 and 3 , Figure 2 is a scanning electron micrograph of the metal halide skeleton layer in the solar cell of Example 12 before fumigation treatment, and Figure 3 is a scanning electron micrograph of the metal halide skeleton layer in the solar cell of Example 12 after fumigation treatment. A comparison of Figures 2 and 3 shows that the thickness of the metal halide skeleton layer in Figure 3 is significantly thicker than that in Figure 2 . In other words, for a planar metal halide skeleton layer, after fumigation treatment with the skeleton layer bulking agent, the thickness of the metal halide skeleton layer increases significantly, indicating that the entire metal halide skeleton layer becomes more fluffy.

[0127] Second, in conjunction with Figures 4 and 5, Figure 4 is a scanning electron microscope image of the metal halide skeleton layer in the solar cell of Comparative Example 1, and Figure 5 is a scanning electron microscope image of the metal halide skeleton layer in the solar cell of Example 1 after fumigation treatment. By comparing Figures 4 and 5, it can be seen that when the metal halide skeleton layer is formed on the velvet surface in Figure 4, the metal halide skeleton layer is composed of densely stacked particles, while when the metal halide skeleton layer is formed on the velvet surface in Figure 5, the metal halide skeleton is composed of loosely stacked rod-shaped structures. In other words, for the metal halide skeleton layer with a velvet structure that meets shape retention requirements, after the steam fumigation treatment of the skeleton layer loosening agent, the metal halide skeleton layer stacked on the velvet structure has changed from a densely stacked particle stack to a stack of rod-shaped materials, indicating that the looseness of the metal halide skeleton layer has been significantly improved.

[0128] Third, in conjunction with Figures 6 and 7, Figure 6 is a scanning electron microscope image of the perovskite layer formed in the solar cell of the comparative example 1, and Figure 7 is a scanning electron microscope image of the perovskite layer formed in the solar cell of Example 1. By comparing the observations at the bottom of the pyramid velvet structure in Figures 6 and 7, it can be seen that there are more bright substances at the bottom of the tower in Figure 6, indicating that when the dense metal halide skeleton layer reacts with the organic cation solution without fumigation treatment, it does lead to obvious lead iodide residue problems. The brightness of the substance at the bottom of the tower in Figure 7 is reduced and the amount is also reduced, indicating that after fumigation treatment and then spin coating the organic cation solution, the lead iodide residue problem at the bottom of the tower can indeed be improved, and on this basis, the shape retention requirements of the velvet structure can still be met, and no shape retention problems occur.

[0129] Fourth, further referring to Figure 8, Figure 8 is a scanning electron microscope image of the metal halide skeleton layer under different fumigation time conditions, specifically corresponding to the scanning electron microscope images of the metal halide skeleton layer before fumigation treatment in Example 1, and after fumigation treatment in Example 6, Example 7, Example 8, Example 1, and Example 9. As can be seen from Figure 8, after 30 seconds of fumigation treatment, the looseness of the metal halide skeleton layer has been improved. When the fumigation treatment time reaches more than 3 minutes (i.e., the fumigation treatment time is 3 minutes to 10 minutes), the morphology of the metal halide skeleton layer (specifically, the lead iodide skeleton layer) is no longer granular, but rod-shaped, thereby greatly improving the looseness of the originally dense metal halide skeleton layer.

[0130] In addition, although different DMSO volume concentrations are used in Examples 1 to 5 of the present application, the metal halide skeleton layer can be loosened under the above-mentioned volume concentration conditions. Although different fumigation temperatures are used in Examples 1, 10 and 11, the metal halide skeleton layer can be loosened under the above-mentioned fumigation temperature conditions. In addition, Example 12 uses a skeleton layer loosening agent N,N-dimethylformamide solvent different from that in Example 1. After fumigation treatment with the vapor of this solvent, the metal halide skeleton layer can also be loosened, but the overall looseness of Example 1 is better. Therefore, using dimethyl sulfoxide as the skeleton layer loosening agent has a more ideal loosening effect.

[0131] The above is a detailed introduction to the perovskite layer and its preparation method, solar cell, and photovoltaic module disclosed in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the technical solution and core ideas of the present invention: At the same time, for those skilled in the art, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing a perovskite layer, characterized in that: The method for preparing the perovskite layer comprises the following steps: preparing a metal halide skeleton layer; The metal halide skeleton layer is treated by steam fumigation of a skeleton layer loosening agent; wherein the skeleton layer loosening agent is a dimethyl sulfoxide solvent and / or an N,N-dimethylformamide solvent; The perovskite layer is prepared by coating an organic cation solution on the metal halide skeleton layer after fumigation.

2. The method for preparing a perovskite layer according to claim 1, characterized in that: The step of using the steam fumigation of the skeleton layer loosening agent to treat the metal halide skeleton layer is: Evenly coating the skeleton layer loosening agent on the bottom edge of the container; Heating the container so that the steam of the skeleton layer loosening agent is distributed in the inner space of the container; The substrate formed with the metal halide skeleton layer is placed in the container and fumigated in the steam of the skeleton layer loosening agent.

3. The method for preparing a perovskite layer according to claim 2, characterized in that: In the step of heating the container to distribute the steam of the skeleton layer loosening agent in the inner space of the container, the heating time is 15 minutes to 30 minutes and the heating temperature is 60° C. to 80° C.

4. The method for preparing a perovskite layer according to claim 2, characterized in that: In the step of placing the substrate formed with the metal halide skeleton layer in the container and fumigating it in the steam of the skeleton layer loosening agent, the fumigation time is 30 seconds to 10 minutes.

5. The method for preparing a perovskite layer according to claim 2, characterized in that: In the step of treating the metal halide skeleton layer with the steam of the skeleton layer loosening agent, the volume concentration of the skeleton layer loosening agent in the container is 2.83×10 -2 μL / cm 3 ~4.72×10 -2 μL / cm 3 .

6. The method for preparing a perovskite layer according to claim 3, characterized in that: The material of the metal halide skeleton layer has a rod-like structure.

7. The method for preparing a perovskite layer according to any one of claims 1 to 4, characterized in that: The step of preparing the metal halide skeleton layer is: evaporating metal halide on a substrate with a velvet structure to form the metal halide skeleton layer.

8. The method for preparing a perovskite layer according to claim 7, characterized in that: The metal halide is one or more of lead halide, cesium halide and rubidium halide.

9. The method for preparing a perovskite layer according to claim 7, characterized in that: In the step of preparing the metal halide skeleton layer, PbI2 and CsBr in a molar ratio of 5:1 to 10:1 are co-evaporated on the substrate to form the metal halide skeleton layer.

10. The method for preparing a perovskite layer according to claim 9, characterized in that: The thickness of the metal halide skeleton layer is 300nm-400nm.

11. The method for preparing a perovskite layer according to any one of claims 1 to 6, characterized in that: The step of coating the organic cation solution on the metal halide skeleton layer after fumigation to prepare the perovskite layer is: Spin coating the organic cation solution onto the metal halide skeleton layer after fumigation; Annealing is performed after spin coating.

12. The method for preparing a perovskite layer according to claim 11, characterized in that: The spin coating speed of the organic cationic solution is 3500 rpm to 4500 rpm, the spin coating acceleration is 3500 rpm / s to 4500 rpm / s, and the spin coating time is 20s to 40s.

13. The method for preparing a perovskite layer according to claim 11, characterized in that: The annealing temperature is 100°C to 150°C.

14. The method for preparing a perovskite layer according to claim 13, characterized in that: The annealing time is 20 min to 40 min.

15. The method for preparing a perovskite layer according to claim 11, characterized in that: The organic cation solution consists of FAI, MABr and MACl.

16. The method for preparing a perovskite layer according to claim 15, characterized in that: The concentration of the organic cation solution is 80 mg / mL to 100 mg / mL.

17. The method for preparing a perovskite layer according to claim 15, characterized in that: The amount of the organic cation solution used is 80 μL to 130 μL.

18. A perovskite layer, characterized in that: The perovskite layer is prepared by the method for preparing a perovskite layer according to any one of claims 1 to 17.

19. A solar cell, characterized in that: The solar cell comprises a perovskite layer prepared by the method for preparing a perovskite layer according to any one of claims 1 to 17, or the solar cell comprises the perovskite layer according to claim 18.

20. A photovoltaic module, characterized in that: The photovoltaic module comprises the solar cell as claimed in claim 19.

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