Perovskite thin film and preparation method thereof, perovskite cell, three-junction solar cell and photovoltaic module

Abstract

The embodiment of the invention provides a perovskite thin film and a preparation method thereof, a perovskite cell, a three-junction solar cell and a photovoltaic module, and relates to the technical field of solar cells. The preparation method of the perovskite thin film comprises the following steps: coating a perovskite precursor solution on a substrate, and annealing to obtain a perovskite layer; the perovskite layer comprises a first surface and a second surface which are oppositely arranged, and the first surface of the perovskite layer is arranged on the substrate; applying pressure to the second surface of the perovskite layer, and sequentially performing first-stage hot-pressing treatment, second-stage hot-pressing treatment and third-stage hot-pressing treatment; wherein the first-stage hot pressing treatment is carried out in an atmosphere containing dimethylformamide steam and inert gas; the second-stage hot pressing treatment is carried out in an inert gas-containing atmosphere; and the third-stage hot pressing treatment is carried out in an atmosphere containing oxygen and inert gas. Through multi-stage hot pressing treatment, the crystallization uniformity of the perovskite thin film can be improved, the defect density of the perovskite thin film is reduced, and the perovskite thin film is good in crystal quality, high in surface flatness and good in covering effect.

Description

Technical Field

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

[0002] Perovskite solar cells (PSCs), as an emerging photovoltaic technology, have attracted widespread attention in laboratories and industry in recent years. Their core advantages lie in high efficiency, low cost and relatively simple preparation process. Perovskite materials are a type of composite materials with ABX3 structure, where A is an organic or inorganic cation and B is a metal cation (such as Pb 2+ ), X is a halogen anion (such as C – , Br – , I – ). These materials have excellent photoelectric conversion efficiency, wide spectral response range, adjustable band gap and flexible material design, making them ideal for high-efficiency photovoltaic devices. Perovskite materials are mostly applied to photovoltaic devices such as perovskite solar cells in the form of thin films. The crystal quality of perovskite films directly determines the performance of photovoltaic devices.

[0003] At present, perovskite films prepared by spin coating, slit coating and other methods have problems such as uneven crystallization, increased porosity between grains, poor crystal quality, low surface flatness, and poor coverage, which affect the open circuit voltage, fill factor and other performance parameters of photovoltaic devices.

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

[0005] The embodiments of the present application provide a perovskite film with high crystal uniformity, low defect density, good crystal quality, high surface flatness and good coverage effect, and a preparation method thereof, a perovskite cell, a triple-junction solar cell and a photovoltaic module to solve or alleviate the technical problems raised above.

[0006] To achieve the above purpose, this application adopts the following technical solutions: A method for preparing a perovskite film comprises the following steps: Coating a perovskite precursor solution on a substrate and annealing to obtain a perovskite layer; the perovskite layer comprises a first surface and a second surface arranged opposite to each other, and the first surface of the perovskite layer is arranged on the substrate; Applying pressure to the second surface of the perovskite layer, and sequentially performing a first stage hot pressing treatment, a second stage hot pressing treatment, and a third stage hot pressing treatment; The first stage of hot pressing treatment is carried out in an atmosphere containing dimethylformamide vapor and an inert gas; the second stage of hot pressing treatment is carried out in an atmosphere containing an inert gas; and the third stage of hot pressing treatment is carried out in an atmosphere containing oxygen and an inert gas.

[0007] In some embodiments, during the first stage of hot pressing, the volume ratio of dimethylformamide vapor in the atmosphere containing dimethylformamide vapor and inert gas is 5-10%; and / or During the third stage of hot pressing, the volume ratio of oxygen in the atmosphere containing oxygen and inert gas is 1-3%.

[0008] In some embodiments, during the first stage of hot pressing, the pressure is 0.5-1.0 MPa; and / or During the second stage of hot pressing, the pressure is 3.0-5.0 MPa; and / or During the third stage of hot pressing, the pressure gradually decreases from 3.0-5.0 MPa to 0-2.0 MPa.

[0009] In some embodiments, during the first stage of hot pressing, the hot pressing time is 2-5 minutes and the temperature is 70-80° C.; and / or During the second stage of hot pressing, the hot pressing time is 3-6 minutes and the temperature is 100-120°C; and / or During the third stage of hot pressing treatment, the hot pressing time is 2-15 minutes, and the temperature is gradually reduced from 100-120° C. to room temperature.

[0010] In some embodiments, during the first stage of hot pressing, the volume ratio of dimethylformamide vapor in the atmosphere containing dimethylformamide vapor and inert gas is 5-10%, the hot pressing time is 2-5 min, the temperature is 70-80° C., and the pressure is 0.5-1.0 MPa; and / or During the second stage of hot pressing, the hot pressing time is 3-6 min, the temperature is 100-120° C., and the pressure is 3.0-5.0 MPa; and / or During the third stage of hot pressing, the volume ratio of oxygen in the atmosphere containing oxygen and inert gas is 1-3%, the hot pressing time is 2-15 minutes, the temperature gradually decreases from 100-120°C to room temperature, and the pressure gradually decreases from 3.0-5.0MPa to 0-2.0MPa.

[0011] In some of the embodiments, after forming the perovskite layer and before applying pressure to the second surface of the perovskite layer, the process further includes: disposing a buffer layer on the second surface of the perovskite layer.

[0012] In some of the embodiments, the method further includes: after completing the third stage hot pressing treatment, removing the buffer layer, cleaning the second surface of the perovskite layer with isopropyl alcohol, and then performing annealing.

[0013] The present application also provides a perovskite film prepared by the above method.

[0014] The present application also provides a perovskite solar cell, comprising: a perovskite film, wherein the perovskite film is prepared by the above method.

[0015] The present application also provides a triple-junction solar cell, comprising: a first cell, a second cell, and a third cell stacked in sequence; the second cell comprises a second perovskite film, and the third cell comprises a third perovskite film; Wherein, the second perovskite film is prepared by the above method; And / or, the third perovskite film is prepared by the above method.

[0016] The present application also provides a photovoltaic module, which at least includes the perovskite solar cell as described above; And / or, the photovoltaic module at least includes the triple-junction solar cell as described above.

[0017] The above technical solution adopted in the embodiment of the present application may have the following advantages: The atmosphere of the first stage of hot pressing treatment contains dimethylformamide vapor (DMF vapor) and inert gas. DMF vapor can promote the softening of the surface of the perovskite layer and the rearrangement of the grains without destroying the surface morphology of the perovskite layer, while improving the density of the perovskite layer. The second stage of hot pressing treatment is carried out in an atmosphere containing inert gas, which can accelerate the rapid densification of perovskite crystals, reduce the number of grain boundaries, fill the pores inside the film, and the inert atmosphere inhibits the volatilization of perovskite components such as methylamine, bromine or iodine, which is beneficial to ensure the quality of the perovskite layer. The third stage of hot pressing treatment is carried out in an atmosphere containing oxygen and inert gas, and trace oxygen and film Surface defects (such as uncoordinated lead ions) react to form a passivation layer, reducing surface recombination centers. The pressure applied to the second side of the perovskite layer can also ensure the stability of the surface morphology of the perovskite layer during the passivation process. Applying pressure to the perovskite layer and sequentially performing the first stage hot pressing treatment, the second stage hot pressing treatment, and the third stage hot pressing treatment can greatly improve the crystallization uniformity of the perovskite film and greatly reduce the defect density of the perovskite film. The perovskite film has good crystal quality, high surface flatness, and good coverage effect. When the perovskite film is used in photovoltaic devices, it can effectively improve the performance parameters of the photovoltaic devices such as the open circuit voltage and fill factor. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0019] Figure 1 is a schematic structural diagram of a triple-junction solar cell provided in an embodiment of the present application; Figure 2 is a schematic diagram of the changes of the perovskite layer before and after the hot pressing treatment of the perovskite layer provided in an embodiment of the present application; Figure 3 is a morphology diagram of the second perovskite film provided in Example 1 of the present application; Figure 4 is a morphology diagram of the second perovskite film provided in Comparative Example 1 of the present application; Figure 5 is a morphology diagram of the second perovskite film provided in Comparative Example 2 of the present application; Figure 6 It is a JV diagram of Example 1 of the present application and Comparative Examples 1-2.

[0020] Description of reference numerals: 01. First electrode; 02. First hole transport layer; 03. Small velvet crystalline silicon; 04. First electron transport layer; 05. First composite layer; 06. Second hole transport layer; 07. Second perovskite film; 08. Second electron transport layer; 09. Second composite layer; 10. Third hole transport layer; 11. Third perovskite film; 12. Third electron transport layer; 13. Second electrode; 111. First battery; 112. Second battery; 113. Third battery; 14. Heating platform; 15. Perovskite layer; 16. Buffer layer; 17. Hydraulic pressure head. DETAILED DESCRIPTION

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

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

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

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

[0025] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical range disclosed in the present application should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows for broadly including quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0026] The present application aims to provide a perovskite film and a preparation method thereof, a perovskite cell, a triple-junction solar cell and a photovoltaic module. The atmosphere of the first stage hot pressing treatment contains dimethylformamide vapor (DMF vapor) and an inert gas. The DMF vapor can promote the softening of the surface of the perovskite layer and the rearrangement of the grains without destroying the surface morphology of the perovskite layer, while improving the density of the perovskite layer. The second stage hot pressing treatment is carried out in an atmosphere containing an inert gas, which can accelerate the rapid densification of the perovskite crystals, reduce the number of grain boundaries, fill the pores inside the film, and the inert atmosphere inhibits the volatilization of perovskite components such as methylamine, bromine or iodine, which is beneficial to ensure the quality of the perovskite layer. The third stage hot pressing treatment is carried out in an atmosphere containing oxygen. The process is carried out in an atmosphere of oxygen and inert gas, trace oxygen reacts with surface defects of the film (such as uncoordinated lead ions) to form a passivation layer, reducing surface recombination centers. The pressure applied to the second side of the perovskite layer can also ensure the stability of the surface morphology of the perovskite layer during the passivation process. Applying pressure to the perovskite layer and sequentially performing the first stage hot pressing treatment, the second stage hot pressing treatment, and the third stage hot pressing treatment can greatly improve the crystallization uniformity of the perovskite film and greatly reduce the defect density of the perovskite film. The perovskite film has good crystal quality, high surface flatness, and good coverage effect. When the perovskite film is used in photovoltaic devices, it can effectively improve the performance parameters of the photovoltaic devices such as the open circuit voltage and fill factor.

[0027] Below, exemplary embodiments of the present application will be described in more detail with reference to the accompanying drawings. It should be noted that these exemplary embodiments can be implemented in many different forms and should not be construed as being limited to the embodiments described herein.

[0028] The present invention provides a method for preparing a perovskite film, comprising the following steps: The perovskite precursor solution is coated on the substrate and annealed to obtain a perovskite layer; the perovskite layer comprises a first surface and a second surface arranged opposite to each other, and the first surface of the perovskite layer is arranged on the substrate; Applying pressure to the second surface of the perovskite layer, and sequentially performing a first stage hot pressing treatment, a second stage hot pressing treatment, and a third stage hot pressing treatment; The first stage of hot pressing treatment is carried out in an atmosphere containing dimethylformamide vapor and an inert gas; the second stage of hot pressing treatment is carried out in an atmosphere containing an inert gas; and the third stage of hot pressing treatment is carried out in an atmosphere containing oxygen and an inert gas.

[0029] In the embodiment of the present application, the perovskite precursor solution includes: a perovskite material and a solvent. The perovskite material has an ABX3 structure; A is usually a formamidinium cation (FA + ), methylammonium cation (MA + ) and cesium ions (Cs + ), B is usually a divalent cation such as lead ion (Pb 2+) and tin ions (Sn 2+ ) one or more, X is usually a halogen anion such as iodide ion (I – ) and (Br – ) or more; wherein the concentration of B is 1 mol / L to 2 mol / L. In the embodiment of the present application, preferably, when a large-area perovskite film is prepared by a slit coating method, the selected Pb 2+ The concentration does not exceed 2 mol / L to obtain a suitable film thickness and a high film quality. The thickness of the perovskite light absorption layer can be 300-800 nm. The solvent in the perovskite precursor solution can be one or more of N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO) and acetonitrile (ACN). When preparing the perovskite light absorption layer, the above solvents can be used to dissolve the perovskite material and the organic cations, which helps to form a uniform solution, improve the solubility of the perovskite precursor solution, and is conducive to the preparation of a high-quality perovskite light absorption layer. The method of coating the perovskite precursor solution on the substrate can be selected from one or more of slit coating, blade coating, spin coating, etc.

[0030] In the embodiment of the present application, when annealing to form a perovskite layer, the annealing temperature can be 100~150℃ (for example, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃), and the annealing time can be 10~30min (for example, 10min, 15min, 20min, 25min, 30min). In the embodiment of the present application, the first surface can be the back surface, and the second surface can be the front surface; that is, the perovskite layer includes a front surface and a back surface that are relatively arranged, and the back surface of the perovskite layer is arranged on the substrate; after applying pressure to the front surface of the perovskite layer, the perovskite layer can be hot-pressed. When the perovskite layer is subjected to the first stage hot-pressing treatment, the second stage hot-pressing treatment, and the third stage hot-pressing treatment, the temperature can be 60~150℃, and the pressure can be 0.5~10.0MPa. The temperature and pressure can be limited according to actual needs.

[0031] In the embodiment of the present application, the volume rate of dimethylformamide vapor in the atmosphere containing dimethylformamide vapor and inert gas can be 5-10%, and the remainder is inert gas, that is, the volume rate of inert gas in the atmosphere containing dimethylformamide vapor and inert gas is 90-95%. The volume rate of oxygen in the atmosphere containing oxygen and inert gas can be 1-3%, and the remainder is inert gas, that is, the volume rate of inert gas in the atmosphere containing dimethylformamide vapor and inert gas is 97-99%. It is also possible to adjust the content of each gas in the hot pressing atmosphere according to actual needs. In addition, the inert gas can include one or more of nitrogen and argon.

[0032] In an embodiment of the present application, a pressure component may be used to apply pressure to the second surface of the perovskite layer, wherein the component that applies pressure to the second surface of the perovskite layer may include one or more of an airbag pressure head and a hydraulic pressure head. When the perovskite layer is subjected to the first stage hot pressing treatment, the second stage hot pressing treatment, and the third stage hot pressing treatment, the perovskite layer may be placed on a heating table to facilitate heating and hot pressing of the perovskite layer. During the hot pressing treatment, the object of the hot pressing treatment may be only the perovskite layer, and the object of the hot pressing treatment may also be a substrate with a perovskite layer, a battery cell with a perovskite layer, etc. The perovskite layer or the object to be hot pressed with a perovskite layer may be hot pressed by applying pressure to the second surface of the perovskite layer using a pressure component. When the object of the hot pressing treatment is only the perovskite layer, see Figure 2 , placing the perovskite layer 15 on the heating platform 14; placing a polyethylene (PE) film as a buffer layer 16 on the front of the perovskite layer 15, applying pressure to the front of the perovskite layer 15 through a hydraulic pressure head 17, and performing a first stage hot pressing treatment, a second stage hot pressing treatment, and a third stage hot pressing treatment in sequence.

[0033] In the embodiment of the present application, the atmosphere of the first stage hot pressing treatment contains dimethylformamide vapor (DMF vapor) and inert gas. The DMF vapor can promote the softening of the surface of the perovskite layer and the rearrangement of the grains without destroying the surface morphology of the perovskite layer, while improving the density of the perovskite layer. The second stage hot pressing treatment is carried out in an atmosphere containing an inert gas, which can accelerate the rapid densification of the perovskite crystals, reduce the number of grain boundaries, fill the pores inside the film, and the inert atmosphere inhibits the volatilization of perovskite components such as methylamine, bromine or iodine, which is beneficial to ensure the quality of the perovskite layer. The third stage hot pressing treatment is carried out in an atmosphere containing oxygen and inert gas, and trace oxygen The gas reacts with the surface defects of the film (such as uncoordinated lead ions) to form a passivation layer, which reduces the surface recombination centers. The pressure applied to the second side of the perovskite layer can also ensure the stability of the surface morphology of the perovskite layer during the passivation process. Applying pressure to the perovskite layer and sequentially performing the first stage hot pressing treatment, the second stage hot pressing treatment, and the third stage hot pressing treatment can greatly improve the crystallization uniformity of the perovskite film and greatly reduce the defect density of the perovskite film. The perovskite film has good crystal quality, high surface flatness, and good coverage effect. When the perovskite film is used in photovoltaic devices, it can effectively improve the performance parameters of the photovoltaic devices such as the open circuit voltage and fill factor.

[0034] In some embodiments, during the first stage of hot pressing, the volume fraction of dimethylformamide vapor in the atmosphere containing dimethylformamide vapor and inert gas is 5-10% (e.g., 5%, 6%, 7%, 8%, 9%, 10%); and / or During the third stage hot pressing treatment, the volume ratio of oxygen in the atmosphere containing oxygen and inert gas is 1 to 3% (eg, 1%, 2%, 3%).

[0035] In the embodiment of the present application, controlling the content of DMF vapor in the atmosphere of the first stage of hot pressing treatment can further promote the softening of the surface of the perovskite layer and the rearrangement of the grains, thereby further improving the density of the perovskite layer.

[0036] In the embodiment of the present application, the oxygen content in the atmosphere of the third stage of hot pressing treatment is controlled, and trace oxygen reacts with surface defects of the film (such as uncoordinated lead ions) to form a higher quality passivation layer, further reducing surface recombination centers, which is beneficial to improving the photoelectric conversion efficiency of solar cells.

[0037] In some embodiments, during the first stage of hot pressing, the pressure is 0.5-1.0 MPa (e.g., 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa); and / or During the second stage hot pressing, the pressure is 3.0-5.0 MPa (e.g., 3.0 MPa, 3.5 MPa, 4.0 MPa, 4.5 MPa, 5.0 MPa); and / or During the third stage of hot pressing, the pressure gradually decreased from 3.0~5.0MPa to 0~2.0MPa.

[0038] In the embodiment of the present application, the third stage of hot pressing treatment is a process of gradually releasing pressure.

[0039] In the embodiments of the present application, controlling the pressure during the hot pressing process can further improve the morphology of the perovskite film, enhance the crystallization uniformity of the perovskite film, and reduce the defect density of the perovskite film. When the perovskite film is used in photovoltaic devices, the performance parameters such as the open circuit voltage and fill factor of the photovoltaic device can be further improved.

[0040] In some embodiments, during the first stage of hot pressing, the hot pressing time is 2-5 min (e.g., 2 min, 3 min, 4 min, 5 min), and the temperature is 70-80° C. (e.g., 70° C., 72° C., 74° C., 76° C., 78° C., 80° C.); and / or During the second stage of hot pressing, the hot pressing time is 3-6 min (e.g., 3 min, 4 min, 5 min, 6 min) and the temperature is 100-120° C. (e.g., 100° C., 105° C., 110° C., 115° C., 120° C.); and / or During the third stage of hot pressing, the hot pressing time is 2 to 15 minutes (eg, 2 minutes, 5 minutes, 10 minutes, 15 minutes), and the temperature is gradually reduced from 100 to 120°C to room temperature.

[0041] In the embodiment of the present application, the third stage of hot pressing treatment is a process in which the temperature is gradually reduced (cooled).

[0042] In the embodiments of the present application, controlling the temperature and time during the hot pressing process can further improve the morphology of the perovskite film, enhance the crystallization uniformity of the perovskite film, and reduce the defect density of the perovskite film. When the perovskite film is used in photovoltaic devices, the performance parameters such as the open circuit voltage and fill factor of the photovoltaic device can be further improved.

[0043] In some embodiments, during the first stage of hot pressing, the volume ratio of dimethylformamide vapor in the atmosphere containing dimethylformamide vapor and inert gas is 5-10%, the hot pressing time is 2-5 min, the temperature is 70-80° C., and the pressure is 0.5-1.0 MPa; and / or During the second stage of hot pressing, the hot pressing time is 3-6 minutes, the temperature is 100-120°C, and the pressure is 3.0-5.0 MPa; and / or During the third stage of hot pressing, the volume ratio of oxygen in the atmosphere containing oxygen and inert gas is 1~3%, the hot pressing time is 2~15min, the temperature gradually decreases from 100~120℃ to room temperature, and the pressure gradually decreases from 3.0~5.0MPa to 0~2.0MPa.

[0044] In the embodiments of the present application, the atmosphere, pressure, temperature, time and other parameters during the hot pressing process are controlled simultaneously, which can further improve the morphology of the perovskite film, enhance the crystallization uniformity of the perovskite film, and reduce the defect density of the perovskite film. When the perovskite film is used in photovoltaic devices, the performance parameters such as the open circuit voltage and fill factor of the photovoltaic device can be further improved.

[0045] In some of the embodiments, after forming the perovskite layer and before applying pressure to the second surface of the perovskite layer, the method further includes: disposing a buffer layer on the second surface of the perovskite layer.

[0046] In the embodiment of the present application, the material of the buffer layer includes but is not limited to one or more of polyimide (Kapton), polyethylene terephthalate (PET), and polyethylene (PE) film. The buffer layer is made of a relatively flexible material, which plays a role in protecting the perovskite film and is conducive to ensuring the quality of the perovskite film. The thickness of the buffer layer can be in the nanometer to millimeter level, and the thickness of the buffer layer can be controlled according to the material properties. The buffer layer is preferably covered with the second side of the perovskite layer to fully protect the perovskite film.

[0047] In some of the embodiments, the method further includes: after completing the third stage hot pressing treatment, removing the buffer layer, cleaning the second side of the perovskite layer with isopropyl alcohol, and then annealing.

[0048] In the embodiment of the present application, after the hot pressing treatment, the second side of the perovskite layer is cleaned with isopropyl alcohol and then annealed, which can effectively remove impurities and residues on the surface of the perovskite film and improve the quality of the perovskite film; it also has the effect of improving the surface morphology of the perovskite film, further improving the quality of the perovskite film.

[0049] The present application also provides a perovskite film prepared by the above method.

[0050] In the embodiment of the present application, pressure is applied to the perovskite layer, and the first stage hot pressing treatment, the second stage hot pressing treatment, and the third stage hot pressing treatment are performed in sequence, which can greatly improve the crystallization uniformity of the perovskite film and greatly reduce the defect density of the perovskite film. The perovskite film has good crystal quality, high surface flatness, and good coverage effect. When the perovskite film is used in photovoltaic devices, it can effectively improve performance parameters such as the open circuit voltage and fill factor of the photovoltaic device.

[0051] The present application also provides a perovskite solar cell, comprising: a perovskite film, wherein the perovskite film is prepared by the above method.

[0052] In the embodiment of the present application, the perovskite film is prepared by the above method, and the perovskite solar cell also has the advantages possessed by the above perovskite film.

[0053] The present application also provides a triple-junction solar cell, comprising: a first cell, a second cell, and a third cell stacked in sequence; the second cell comprises a second perovskite film, and the third cell comprises a third perovskite film; Wherein, the second perovskite film is prepared by the above method; And / or, the third perovskite film is prepared by the above method.

[0054] In the embodiment of the present application, when the first battery is a bottom battery, it can be selected from any one of a crystalline silicon battery, a perovskite battery, a battery made of Group III-V semiconductor materials (such as a gallium arsenide solar cell), and a battery made of Group II-VI semiconductor materials (such as a cadmium telluride solar cell).

[0055] In the embodiment of the present application, the second battery is an intermediate battery, specifically a perovskite battery; the third battery is a top battery, specifically a perovskite battery.

[0056] In the embodiment of the present application, when the first battery is a silicon-bottom battery, and the second battery and the third battery are both perovskite batteries, the triple-junction solar cell includes: a first electrode 01, a first hole transport layer 02, a small suede crystalline silicon 03, a first electron transport layer 04, a first composite layer 05, a second hole transport layer 06, a second perovskite film 07, a second electron transport layer 08, a second composite layer 09, a third hole transport layer 10, a third perovskite film 11, a third electron transport layer 12, and a second electrode 13 which are stacked in sequence. Among them, the first electrode 01 and the second electrode 13 can be one or more of ITO (indium tin oxide), FTO (fluorine-doped tin oxide), IZO (indium zinc oxide) and silver; the materials of the first hole transport layer 02, the second hole transport layer 06 and the third hole transport layer 10 include but are not limited to organic small molecule materials (PTAA, HTM-1, HTM-2, etc.), inorganic materials (NiO, CuO, etc.); the materials of the first electron transport layer 04, the second electron transport layer 08 and the third electron transport layer 12 include but are not limited to transparent oxides such as TiO2, SnO2, ZnO, etc.; the materials of the first composite layer 05 and the second composite layer 09 include but are not limited to ITO (indium tin oxide), FTO (fluorine-doped tin oxide) and IZO (indium zinc oxide).

[0057] In the embodiments of the present application, the preparation process of the second perovskite film (the second perovskite film may be a medium-bandgap perovskite film) and / or the third perovskite film (the third perovskite film may be a wide-bandgap perovskite film) is optimized, which can effectively improve the crystallization uniformity of the perovskite film and significantly reduce the defect density of the perovskite film. The perovskite film has good crystal quality, high surface flatness, and good coverage effect, thereby effectively improving performance parameters such as the open-circuit voltage and fill factor of the photovoltaic device.

[0058] In the embodiment of the present application, the preparation process of the second perovskite film is optimized, and the quality of the second perovskite film is improved, which can provide a good substrate for the growth of the third perovskite film, thereby greatly improving the quality of the third perovskite film, and can effectively solve the problem that the second perovskite film in the triple-junction solar cell has poor film quality, and cannot provide a good substrate for the growth of the third perovskite film, resulting in worse film quality of the third perovskite film, and greatly reducing the open circuit voltage and fill factor of the triple-junction solar cell. In addition, in the embodiment of the present application, the preparation process of the second perovskite film is optimized, which can improve the quality of the second perovskite film and the third perovskite film, greatly reduce the occurrence of leakage current, improve the photoelectric conversion rate of the triple-junction solar cell, and improve the stability of the triple-junction solar cell.

[0059] In the embodiment of the present application, pressure is applied to the perovskite layer, and the first stage hot pressing treatment, the second stage hot pressing treatment, and the third stage hot pressing treatment are performed in sequence, which can greatly improve the crystallization uniformity of the perovskite film and greatly reduce the defect density of the perovskite film. The perovskite film has good crystal quality, high surface flatness, and good coverage effect, thereby effectively improving the performance parameters of the triple-junction solar cell such as the open circuit voltage and fill factor.

[0060] The following specific examples further illustrate the present application, but should not be construed as limiting the present application. Without departing from the spirit and substance of the present application, modifications or replacements made to the methods, steps or conditions of the present application are within the scope of the present application.

[0061] Example 1 A triple junction solar cell, such as Figure 1 As shown, it includes: a first battery 111, a second battery 112, and a third battery 113 stacked in sequence; more specifically, a triple junction solar cell includes: a first electrode 01, a first hole transport layer 02, a small textured crystalline silicon 03, a first electron transport layer 04, a first composite layer 05, a second hole transport layer 06, a second perovskite film 07, a second electron transport layer 08, a second composite layer 09, a third hole transport layer 10, a third perovskite film 11, a third electron transport layer 12, and a second electrode 13 stacked in sequence; wherein, The first electrode 01, the first hole transport layer 02, the small velvet crystalline silicon 03, the first electron transport layer 04, and the first composite layer 05 are the first battery 111, and the first battery 111 is a silicon bottom battery; the first composite layer 05, the second hole transport layer 06, the second perovskite film 07, the second electron transport layer 08, and the second composite layer 09 stacked in sequence are the second battery 112; the second composite layer 09, the third hole transport layer 10, the third perovskite film 11, the third electron transport layer 12, and the second electrode 13 stacked in sequence are the third battery 113.

[0062] The specific preparation process of triple junction solar cells is as follows: (1) The first cell 111 (silicon bottom cell) was irradiated with UV light for 15 minutes, and then a SAM solution (MEo-2PACz: 2PACz was 3:1, and the total concentration was 0.5 mg / mL) was spin-coated on the front side of the first cell 111 (silicon bottom cell) at a rate of 4000 rpm for 30 seconds, and then annealed at 100°C for 10 minutes to form a second hole transport layer 06.

[0063] (2) Preparation of the second perovskite film 07: 1) Medium-bandgap perovskite (FA 0.98 MA 0.02 ) 0.95 Cs 0.05Pb(I 0.98 Br 0.02 )3) Dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 4:1, the concentration of the perovskite material is 1.8 mol / mL, and spin-coated on the front side of the second hole transport layer 06 at a rate of 2000 rpm for 25 seconds, and then spin-coated at a rate of 5000 rpm for 30 seconds, and 200 microliters of chlorobenzene was added 10 seconds before the end of spin coating, and then annealed at 100°C for 20 minutes to form a perovskite layer; 2) Apply pressure to the front of the perovskite layer, and perform the first stage hot pressing treatment, the second stage hot pressing treatment, and the third stage hot pressing treatment in sequence; the first stage hot pressing treatment is carried out in an atmosphere containing dimethylformamide vapor and nitrogen. During the first stage hot pressing treatment, the volume ratio of dimethylformamide vapor in the atmosphere containing dimethylformamide vapor and nitrogen is 5%, the hot pressing time is 2 minutes, the temperature is 70°C, and the pressure is 0.5MPa; the second stage hot pressing treatment is carried out in an atmosphere containing nitrogen. During the second stage hot pressing treatment, the hot pressing time is 3 minutes, the temperature is 100°C, and the pressure is 3.0MPa; the third stage hot pressing treatment is carried out in an atmosphere containing oxygen and nitrogen. During the third stage hot pressing treatment, the volume ratio of oxygen in the atmosphere containing oxygen and nitrogen is 1%, the hot pressing time is 15 minutes, the temperature gradually decreases from 100°C to room temperature, and the pressure gradually decreases from 3.0MPa to 0MPa, forming a second perovskite film 07. Among them, the morphology of the second perovskite film 07 is shown in the figure Figure 3 See Figure 3 It can be seen that the surface of the second perovskite film 07 is smooth and uniform, which shows that the quality of the prepared second perovskite film 07 is very high.

[0064] (3) 12 nm C 60 (fullerene) layer and 30nm SnO2 layer as the corresponding second electron transport layer 08 (C 60 layer + SnO2 layer); a 20 nm IZO layer is prepared on the front side of the second electron transport layer 08 as the second composite layer 09 by evaporation.

[0065] (4) Sputter 15nm NiO on the front side of the second composite layer 09 x The SAM solution (MEo-2PACz:2PACz is 3:1, the total concentration is 0.5 mg / mL) was added to the NiO layer at a speed of 4000 rpm. x The front side of the layer was spin-coated for 30 seconds and then annealed at 100°C for 10 minutes to form the third hole transport layer 10 (NiO x layer + SAM layer).

[0066] (5) Wide bandgap perovskite (FA 0.7 Cs 0.3 Pb(I 0.333 Br 0.667 )3) dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1 with a concentration of 1.0 mol / mL, spin coated on the front side of the third hole transport layer 10 at a rate of 1000 rpm for 10 seconds, and then spin coated at a rate of 4000 rpm for 40 seconds, 160 microliters of anisole was added dropwise 10 seconds before the end, and then annealed at 100°C for 20 minutes to form a third perovskite film 11.

[0067] (6) 12 nm C 60 (fullerene) layer and a 15nm SnO2 layer as the third electron transport layer 12 (C 60 layer + SnO2 layer); a 30nm IZO layer and a 400nm silver electrode are sequentially prepared on the front side of the third electron transport layer 12 by evaporation as the second electrode 13 (IZO layer + silver electrode); in addition, a 110nm MgF2 (magnesium fluoride) layer is evaporated on the top layer of the triple-junction solar cell as an anti-reflection film (anti-reflection film Figure 1 In addition, it should be noted that the size of the triple-junction solar cell in the embodiment of the present application is 2 cm×2 cm, and the effective area of ​​the triple-junction solar cell is 1.1164 square centimeters. The second composite layer 09 and the first composite layer 05 only need to cover the effective area.

[0068] Example 2 The triple-junction solar cell of Example 2 is prepared by referring to the preparation method of Example 1, except that in Example 2, the preparation method of the second perovskite film 07 is as follows: 1) the medium-bandgap perovskite (FA 0.98 MA 0.02 ) 0.95 Cs 0.05 Pb(I 0.98 Br 0.02)3) Dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 4:1, the concentration of the perovskite material is 1.8 mol / mL, and spin-coated on the front side of the second hole transport layer 06 at a rate of 2000 rpm for 25 seconds, and then spin-coated at a rate of 5000 rpm for 30 seconds. 200 microliters of chlorobenzene are added 10 seconds before the end of spin coating, and then annealed at 100°C for 20 minutes to form a perovskite layer; 2) Apply pressure to the front side of the perovskite layer, and perform the first stage hot pressing treatment, the second stage hot pressing treatment, and the third stage hot pressing treatment in sequence; the first stage hot pressing treatment is carried out in an atmosphere containing dimethylformamide vapor and nitrogen. During the first stage hot pressing treatment, The volume ratio of dimethylformamide vapor in the atmosphere of dimethylformamide vapor and nitrogen is 10%, the hot pressing time is 5 minutes, the temperature is 80°C, and the pressure is 1.0 MPa; the second stage hot pressing treatment is carried out in an atmosphere containing nitrogen. During the second stage hot pressing treatment, the hot pressing time is 6 minutes, the temperature is 120°C, and the pressure is 5.0 MPa; the third stage hot pressing treatment is carried out in an atmosphere containing oxygen and nitrogen. During the third stage hot pressing treatment, the volume ratio of oxygen in the atmosphere containing oxygen and nitrogen is 3%, the hot pressing time is 2 minutes, the temperature gradually decreases from 120°C to room temperature, and the pressure gradually decreases from 5.0 MPa to 2.0 MPa, forming a second perovskite film 07.

[0069] Example 3 The triple-junction solar cell of Example 3 is prepared by referring to the preparation method of Example 1, except that in Example 3, the preparation method of the second perovskite film 07 is as follows: 1) the medium-bandgap perovskite (FA 0.98 MA 0.02 ) 0.95 Cs 0.05 Pb(I 0.98 Br 0.02)3) Dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 4:1, the concentration of the perovskite material is 1.8 mol / mL, and spin-coated on the front side of the second hole transport layer 06 at a rate of 2000 rpm for 25 seconds, and then spin-coated at a rate of 5000 rpm for 30 seconds. 200 microliters of chlorobenzene are added 10 seconds before the end of spin coating, and then annealed at 100°C for 20 minutes to form a perovskite layer; 2) Apply pressure to the front side of the perovskite layer, and perform the first stage hot pressing treatment, the second stage hot pressing treatment, and the third stage hot pressing treatment in sequence; the first stage hot pressing treatment is carried out in an atmosphere containing dimethylformamide vapor and nitrogen. During the first stage hot pressing treatment, The volume ratio of dimethylformamide vapor in the atmosphere containing dimethylformamide vapor and nitrogen is 7%, the hot pressing time is 3 minutes, the temperature is 75°C, and the pressure is 0.8 MPa; the second stage hot pressing treatment is carried out in an atmosphere containing nitrogen. During the second stage hot pressing treatment, the hot pressing time is 4 minutes, the temperature is 110°C, and the pressure is 4.0 MPa; the third stage hot pressing treatment is carried out in an atmosphere containing oxygen and nitrogen. During the third stage hot pressing treatment, the volume ratio of oxygen in the atmosphere containing oxygen and nitrogen is 2%, the hot pressing time is 8 minutes, the temperature gradually decreases from 110°C to room temperature, and the pressure gradually decreases from 4.0 MPa to 1.0 MPa, forming a second perovskite film 07.

[0070] Example 4 The triple-junction solar cell of Example 4 is prepared by referring to the preparation method of Example 1, except that in Example 4, the preparation method of the second perovskite film 07 is as follows: 1) the medium-bandgap perovskite (FA 0.98 MA 0.02 ) 0.95 Cs 0.05 Pb(I 0.98 Br 0.02)3) Dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 4:1, the concentration of the perovskite material is 1.8 mol / mL, and spin-coated at a rate of 2000 rpm for 25 seconds on the front side of the second hole transport layer 06, and then spin-coated at a rate of 5000 rpm for 30 seconds, 200 microliters of chlorobenzene is added 10 seconds before the end of spin coating, and then annealed at 100°C for 20 minutes to form a perovskite layer 15; 2) The first battery 111 (silicon bottom battery) forming the perovskite layer 15 is sent to the hot pressing process, the bottom surface of the first battery 111 (silicon bottom battery) is placed on the heating table 14 (the perovskite layer 15 is used as the top surface), and then a polyethylene (PE) film is placed on the front side of the perovskite layer 15 as a buffer layer 16, and pressure is applied to the front side of the perovskite layer 15 by a hydraulic pressure head 17, and the first stage hot pressing treatment, the second stage hot pressing treatment, and the third stage hot pressing treatment are sequentially performed. Treatment; the first stage of hot pressing treatment is carried out in an atmosphere containing dimethylformamide vapor and nitrogen. During the first stage of hot pressing treatment, the volume ratio of dimethylformamide vapor in the atmosphere containing dimethylformamide vapor and nitrogen is 5%, the hot pressing time is 2 minutes, the temperature is 70°C, and the pressure is 0.5MPa; the second stage of hot pressing treatment is carried out in an atmosphere containing nitrogen. During the second stage of hot pressing treatment, the hot pressing time is 3 minutes, the temperature is 100°C, and the pressure is 3.0MPa; the third stage of hot pressing treatment is carried out in an atmosphere containing oxygen and nitrogen. During the third stage of hot pressing treatment, the volume ratio of oxygen in the atmosphere containing oxygen and nitrogen is 1%, the hot pressing time is 15 minutes, the temperature gradually decreases from 100°C to room temperature, and the pressure gradually decreases from 3.0MPa to 0MPa; the third stage of hot pressing treatment is completed to form a second perovskite film 07; and then the buffer layer 16 is removed.

[0071] Example 5 The triple-junction solar cell of Example 5 is prepared by referring to the preparation method of Example 1, except that in Example 5, the preparation method of the second perovskite film 07 is as follows: 1) the medium-bandgap perovskite (FA 0.98 MA 0.02 ) 0.95 Cs 0.05 Pb(I 0.98 Br 0.02)3) dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 4:1, the concentration of the perovskite material is 1.8 mol / mL, and spin-coated at a rate of 2000 rpm for 25 seconds on the front side of the second hole transport layer 06, and then spin-coated at a rate of 5000 rpm for 30 seconds, 200 microliters of chlorobenzene is added 10 seconds before the end of spin coating, and then annealed at 100°C for 20 minutes to form a perovskite layer 15; 2) the first battery 111 (silicon bottom battery) forming the perovskite layer 15 is sent to the hot pressing process, the bottom surface of the first battery 111 (silicon bottom battery) is placed on the heating table 14 (the perovskite layer 15 is used as the top surface), and then a polyethylene (PE) film is placed on the front side of the perovskite layer 15 as a buffer layer 16, and pressure is applied to the front side of the perovskite layer 15 by a hydraulic pressure head 17, and the first stage hot pressing treatment, the second stage hot pressing treatment, and the third stage hot pressing treatment are performed in sequence; the first stage hot pressing treatment is carried out on the surface containing di The hot pressing treatment is carried out in an atmosphere of dimethylformamide vapor and nitrogen. During the first stage of hot pressing treatment, the volume ratio of dimethylformamide vapor in the atmosphere containing dimethylformamide vapor and nitrogen is 5%, the hot pressing time is 2 minutes, the temperature is 70°C, and the pressure is 0.5 MPa; the second stage of hot pressing treatment is carried out in an atmosphere containing nitrogen. During the second stage of hot pressing treatment, the hot pressing time is 3 minutes, the temperature is 100°C, and the pressure is 3.0 MPa; the third stage of hot pressing treatment is carried out in an atmosphere containing oxygen and nitrogen. During the third stage of hot pressing treatment, the volume ratio of oxygen in the atmosphere containing oxygen and nitrogen is 1%, the hot pressing time is 15 minutes, the temperature gradually decreases from 100°C to room temperature, and the pressure gradually decreases from 3.0 MPa to 0 MPa; after completing the third stage of hot pressing treatment, the buffer layer 16 is removed, and the front side of the perovskite layer is cleaned with isopropyl alcohol, and then annealed at 100°C for 5 minutes to form a second perovskite film 07.

[0072] Example 6 The triple-junction solar cell of Example 6 is prepared by referring to the preparation method of Example 1, except that in Example 6, the preparation method of the second perovskite film 07 is as follows: 1) the medium-bandgap perovskite (FA 0.98 MA 0.02 ) 0.95 Cs 0.05 Pb(I 0.98 Br 0.02)3) Dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 4:1, the concentration of the perovskite material is 1.8 mol / mL, and spin-coated on the front side of the second hole transport layer 06 at a rate of 2000 rpm for 25 s, and then spin-coated at a rate of 5000 rpm for 30 s. 200 microliters of chlorobenzene was added 10 s before the end of spin coating, and then annealed at 100°C for 20 minutes to form a perovskite layer; (2) Applying pressure to the front side of the perovskite layer, and sequentially performing a first stage hot pressing treatment, a second stage hot pressing treatment, and a third stage hot pressing treatment; the first stage hot pressing treatment is carried out in an atmosphere containing dimethylformamide vapor and nitrogen. In the first stage hot pressing treatment During the process, the volume ratio of dimethylformamide vapor in the atmosphere containing dimethylformamide vapor and nitrogen is 5%, the hot pressing time is 2 minutes, the temperature is 70°C, and the pressure is 0.5 MPa; the second stage hot pressing treatment is carried out in an atmosphere containing nitrogen. During the second stage hot pressing treatment, the hot pressing time is 3 minutes, the temperature is 100°C, and the pressure is 0.5 MPa; the third stage hot pressing treatment is carried out in an atmosphere containing oxygen and nitrogen. During the third stage hot pressing treatment, the volume ratio of oxygen in the atmosphere containing oxygen and nitrogen is 1%, the hot pressing time is 15 minutes, the temperature gradually decreases from 100°C to room temperature, and the pressure is 0.5 MPa, forming a second perovskite film 07.

[0073] Example 7 The triple-junction solar cell of Example 7 is prepared by referring to the preparation method of Example 1, except that in Example 7, the preparation method of the second perovskite film 07 is as follows: 1) the medium-bandgap perovskite (FA 0.98 MA 0.02 ) 0.95 Cs 0.05 Pb(I 0.98 Br 0.02)3) Dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 4:1, the concentration of the perovskite material is 1.8 mol / mL, and spin-coated on the front side of the second hole transport layer 06 at a rate of 2000 rpm for 25 s, and then spin-coated at a rate of 5000 rpm for 30 s. 200 microliters of chlorobenzene was added 10 s before the end of spin coating, and then annealed at 100°C for 20 minutes to form a perovskite layer; (2) Applying pressure to the front side of the perovskite layer, and sequentially performing a first stage hot pressing treatment, a second stage hot pressing treatment, and a third stage hot pressing treatment; the first stage hot pressing treatment is carried out in an atmosphere containing dimethylformamide vapor and nitrogen. In the first stage hot pressing treatment During the process, the volume ratio of dimethylformamide vapor in the atmosphere containing dimethylformamide vapor and nitrogen is 5%, the hot pressing time is 2 minutes, the temperature is 70°C, and the pressure is 3.0 MPa; the second stage hot pressing treatment is carried out in an atmosphere containing nitrogen. During the second stage hot pressing treatment, the hot pressing time is 3 minutes, the temperature is 100°C, and the pressure is 3.0 MPa; the third stage hot pressing treatment is carried out in an atmosphere containing oxygen and nitrogen. During the third stage hot pressing treatment, the volume ratio of oxygen in the atmosphere containing oxygen and nitrogen is 1%, the hot pressing time is 15 minutes, the temperature gradually decreases from 100°C to room temperature, and the pressure is 3.0 MPa, forming a second perovskite film 07.

[0074] Example 8 The triple-junction solar cell of Example 8 is prepared by referring to the preparation method of Example 1, except that in Example 8, the preparation method of the second perovskite film 07 is as follows: 1) the medium-bandgap perovskite (FA 0.98 MA 0.02 ) 0.95 Cs 0.05 Pb(I 0.98 Br 0.02)3) Dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 4:1, the concentration of the perovskite material is 1.8 mol / mL, and spin-coated on the front side of the second hole transport layer 06 at a rate of 2000 rpm for 25 s, and then spin-coated at a rate of 5000 rpm for 30 s. 200 microliters of chlorobenzene was added 10 s before the end of spin coating, and then annealed at 100 ° C for 20 minutes to form a perovskite layer; (2) Applying pressure to the front side of the perovskite layer, and sequentially performing the first stage hot pressing treatment, the second stage hot pressing treatment, and the third stage hot pressing treatment; the first stage hot pressing treatment is carried out in an atmosphere containing dimethylformamide vapor and nitrogen. During the process, the volume ratio of dimethylformamide vapor in the atmosphere containing dimethylformamide vapor and nitrogen was 5%, the hot pressing time was 2 minutes, the temperature was 100°C, and the pressure was 0.5 MPa; the second stage hot pressing treatment was carried out in an atmosphere containing nitrogen. During the second stage hot pressing treatment, the hot pressing time was 3 minutes, the temperature was 100°C, and the pressure was 3.0 MPa; the third stage hot pressing treatment was carried out in an atmosphere containing oxygen and nitrogen. During the third stage hot pressing treatment, the volume ratio of oxygen in the atmosphere containing oxygen and nitrogen was 1%, the hot pressing time was 15 minutes, the temperature was 100°C, and the pressure gradually decreased from 3.0 MPa to 0 MPa, forming a second perovskite film 07.

[0075] Example 9 The triple-junction solar cell of Example 9 is prepared by referring to the preparation method of Example 1, except that in Example 9, the preparation method of the second perovskite film 07 is as follows: 1) the medium-bandgap perovskite (FA 0.98 MA 0.02 ) 0.95 Cs 0.05 Pb(I 0.98 Br 0.02)3) Dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 4:1, the concentration of the perovskite material is 1.8 mol / mL, and spin-coated on the front side of the second hole transport layer 06 at a rate of 2000 rpm for 25 s, and then spin-coated at a rate of 5000 rpm for 30 s. 200 microliters of chlorobenzene was added 10 s before the end of spin coating, and then annealed at 100°C for 20 minutes to form a perovskite layer; (2) Applying pressure to the front side of the perovskite layer, and sequentially performing a first stage hot pressing treatment, a second stage hot pressing treatment, and a third stage hot pressing treatment; the first stage hot pressing treatment is carried out in an atmosphere containing dimethylformamide vapor and nitrogen. In the first stage hot pressing treatment During the process, the volume ratio of dimethylformamide vapor in the atmosphere containing dimethylformamide vapor and nitrogen is 5%, the hot pressing time is 2 minutes, the temperature is 80°C, and the pressure is 0.5 MPa; the second stage hot pressing treatment is carried out in an atmosphere containing nitrogen. During the second stage hot pressing treatment, the hot pressing time is 3 minutes, the temperature is 80°C, and the pressure is 3.0 MPa; the third stage hot pressing treatment is carried out in an atmosphere containing oxygen and nitrogen. During the third stage hot pressing treatment, the volume ratio of oxygen in the atmosphere containing oxygen and nitrogen is 1%, the hot pressing time is 15 minutes, the temperature is 80°C, and the pressure gradually decreases from 3.0 MPa to 0 MPa, forming a second perovskite film 07.

[0076] Comparative Example 1 The triple-junction solar cell of Comparative Example 1 is prepared by referring to the preparation method of Example 1, except that, in Comparative Example 1, the preparation method of the second perovskite film 07 is as follows: 1) the medium-bandgap perovskite (FA 0.98 MA 0.02 ) 0.95 Cs 0.05 Pb(I 0.98 Br 0.02 )3) Dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 4:1, the concentration of the perovskite material is 1.8 mol / mL, and spin-coated at 2000 rpm for 25 seconds on the front of the second hole transport layer 06, and then spin-coated at 5000 rpm for 30 seconds. 200 microliters of chlorobenzene was added 10 seconds before the end of spin coating, and then annealed at 100°C for 20 minutes. The formed perovskite layer is the perovskite film. Among them, the morphology of the second perovskite film 07 is shown in FIG. Figure 4 As shown, see Figure 4 It can be seen that the surface of the second perovskite film 07 has obvious particle aggregation.

[0077] Comparative Example 2 The triple-junction solar cell of Comparative Example 2 is prepared by referring to the preparation method of Example 1, except that, in Comparative Example 2, the preparation method of the second perovskite film 07 is as follows: 1) the medium-bandgap perovskite (FA0.98 MA 0.02 ) 0.95 Cs 0.05 Pb(I 0.98 Br 0.02 )3) Dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 4:1, the concentration of the perovskite material is 1.8 mol / mL, and spin-coated at 2000 rpm for 25 seconds on the front of the second hole transport layer 06, and then spin-coated at 5000 rpm for 30 seconds. 200 microliters of chlorobenzene were added 10 seconds before the end of spin coating, and then annealed at 100°C for 20 minutes to form a perovskite layer; 2) Apply a pressure of 3 Mpa to the front of the perovskite layer, and heat press for 15 minutes at a temperature of 80°C and a nitrogen atmosphere. Among them, the morphology of the second perovskite film 07 is shown in the figure Figure 5 As shown, see Figure 5 It can be seen that the surface of the second perovskite film 07 has scattered particle aggregations.

[0078] Table 1 Performance test results of triple junction solar cells of Examples 1-9 and Comparative Examples 1-2

[0079] In addition, the JV diagrams of Example 1 and Comparative Examples 1-2 are as follows: Figure 6 As shown, Figure 6 The horizontal axis represents the open circuit voltage VOC (V), and the vertical axis represents the short circuit current density JSC (mA / cm 2). Referring to the battery performance test results of Examples 1-9 and Comparative Examples 1-2, and the JV diagrams of Examples 1 and Comparative Examples 1-2, it can be seen that the atmosphere of the first stage of hot pressing treatment contains dimethylformamide vapor (DMF vapor) and inert gas. DMF vapor can promote the softening of the surface of the perovskite layer and the rearrangement of the grains without destroying the surface morphology of the perovskite layer, while improving the density of the perovskite layer; the second stage of hot pressing treatment is carried out in an atmosphere containing an inert gas, which can accelerate the rapid densification of the perovskite crystals, reduce the number of grain boundaries, fill the pores inside the film, and the inert atmosphere inhibits the volatilization of perovskite components such as methylamine, bromine or iodine, which is beneficial to ensure the quality of the perovskite layer; the third stage of hot pressing treatment The process is carried out in an atmosphere containing oxygen and inert gas. Trace amounts of oxygen react with surface defects of the film (such as uncoordinated lead ions) to form a passivation layer, which reduces surface recombination centers. The pressure applied to the second side of the perovskite layer can also ensure the stability of the surface morphology of the perovskite layer during the passivation process. Applying pressure to the perovskite layer and sequentially performing the first stage hot pressing treatment, the second stage hot pressing treatment, and the third stage hot pressing treatment can greatly improve the crystallization uniformity of the perovskite film and greatly reduce the defect density of the perovskite film. The perovskite film has good crystal quality, high surface flatness, and good coverage effect. When the perovskite film is used in photovoltaic devices, it can effectively improve the performance parameters of the photovoltaic devices, such as the open circuit voltage and fill factor.

[0080] By comparing the battery performance test results of Example 1 and Example 4, it can be seen that Example 4 is provided with a buffer layer, which can protect the perovskite film, is beneficial to ensuring the quality of the perovskite film, and further improves the efficiency of the solar cell.

[0081] By comparing the battery performance test results of Example 4 and Example 5, it can be seen that after Example 5 is hot-pressed, the second side of the perovskite layer is cleaned with isopropyl alcohol and then annealed, which can effectively remove impurities and residues on the surface of the perovskite film and improve the quality of the perovskite film; it also has the effect of improving the surface morphology of the perovskite film, further improving the quality of the perovskite film, and thus improving the efficiency of the solar cell.

[0082] By comparing the battery performance test results of Example 1 and Examples 6-7, it can be seen that reasonable control of the pressure during the hot pressing process can further improve the morphology of the perovskite film, enhance the crystallization uniformity of the perovskite film, and reduce the defect density of the perovskite film. When the perovskite film is used in photovoltaic devices, it can further improve the performance parameters such as the open circuit voltage and fill factor of the photovoltaic device, thereby improving the efficiency of the solar cell.

[0083] By comparing the battery performance test results of Example 1 and Examples 8-9, it can be seen that reasonable control of the temperature and time during the hot pressing process can further improve the morphology of the perovskite film, enhance the crystallization uniformity of the perovskite film, and reduce the defect density of the perovskite film. When the perovskite film is used in photovoltaic devices, it can further improve the open circuit voltage and fill factor of the photovoltaic device and other performance parameters, thereby improving the efficiency of solar cells.

[0084] By comparing the battery performance test results of Examples 1-3 and Examples 6-9, it can be seen that by reasonably controlling parameters such as atmosphere, pressure, temperature and time during the hot pressing process, the morphology of the perovskite film can be further improved, the crystallization uniformity of the perovskite film can be improved, and the defect density of the perovskite film can be reduced. When the perovskite film is used in photovoltaic devices, the performance parameters such as the open circuit voltage and fill factor of the photovoltaic device can be further improved, thereby improving the efficiency of the solar cell.

[0085] The present application may provide a photovoltaic module, the photovoltaic module at least comprising the perovskite solar cell as described above; And / or, the photovoltaic module at least includes the triple-junction solar cell as described above. The photovoltaic cell module also has the advantages possessed by the above-mentioned perovskite solar cell and / or triple-junction solar cell.

[0086] It should be noted that the terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The orientation words "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Therefore, the exemplary term "above..." can include both "above..." and "below..." orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here are interpreted accordingly.

[0087] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0088] It should also be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0089] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0090] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing a perovskite film, characterized in that: The steps include: Coating a perovskite precursor solution on a substrate and annealing to obtain a perovskite layer; the perovskite layer comprises a first surface and a second surface arranged opposite to each other, and the first surface of the perovskite layer is arranged on the substrate; Applying pressure to the second surface of the perovskite layer, and sequentially performing a first stage hot pressing treatment, a second stage hot pressing treatment, and a third stage hot pressing treatment; The first stage of hot pressing treatment is carried out in an atmosphere containing dimethylformamide vapor and an inert gas; the second stage of hot pressing treatment is carried out in an atmosphere containing an inert gas; and the third stage of hot pressing treatment is carried out in an atmosphere containing oxygen and an inert gas.

2. The method for preparing a perovskite thin film according to claim 1, characterized in that: During the first stage of hot pressing, the volume ratio of dimethylformamide vapor in the atmosphere containing dimethylformamide vapor and inert gas is 5-10%; and / or During the third stage of hot pressing, the volume ratio of oxygen in the atmosphere containing oxygen and inert gas is 1-3%.

3. The method for preparing a perovskite thin film according to claim 1, characterized in that: During the first stage of hot pressing, the pressure is 0.5-1.0 MPa; and / or During the second stage of hot pressing, the pressure is 3.0-5.0 MPa; and / or During the third stage of hot pressing, the pressure gradually decreases from 3.0-5.0 MPa to 0-2.0 MPa.

4. The method for preparing a perovskite thin film according to claim 1, characterized in that: During the first stage of hot pressing, the hot pressing time is 2-5 minutes and the temperature is 70-80°C; and / or During the second stage of hot pressing, the hot pressing time is 3-6 minutes and the temperature is 100-120°C; and / or During the third stage of hot pressing treatment, the hot pressing time is 2-15 minutes, and the temperature is gradually reduced from 100-120° C. to room temperature.

5. The method for preparing a perovskite thin film according to claim 1, characterized in that: During the first stage of hot pressing, the volume ratio of dimethylformamide vapor in the atmosphere containing dimethylformamide vapor and inert gas is 5-10%, the hot pressing time is 2-5 minutes, the temperature is 70-80° C., and the pressure is 0.5-1.0 MPa; and / or During the second stage of hot pressing, the hot pressing time is 3-6 min, the temperature is 100-120° C., and the pressure is 3.0-5.0 MPa; and / or During the third stage of hot pressing, the volume ratio of oxygen in the atmosphere containing oxygen and inert gas is 1-3%, the hot pressing time is 2-15 minutes, the temperature gradually decreases from 100-120°C to room temperature, and the pressure gradually decreases from 3.0-5.0MPa to 0-2.0MPa.

6. The method for preparing a perovskite thin film according to any one of claims 1 to 5, characterized in that: After forming the perovskite layer and before applying pressure to the second surface of the perovskite layer, the method further includes: providing a buffer layer on the second surface of the perovskite layer.

7. The method for preparing a perovskite thin film according to claim 6, characterized in that: Also includes: After the third stage of hot pressing is completed, the buffer layer is removed, and the second surface of the perovskite layer is cleaned with isopropyl alcohol, and then annealing is performed.

8. A perovskite film, characterized in that: Prepared by the method according to any one of claims 1 to 7.

9. A perovskite solar cell, characterized in that: include: A perovskite film, wherein the perovskite film is prepared by the method according to any one of claims 1 to 7.

10. A triple junction solar cell, characterized in that: include: A first battery, a second battery, and a third battery are stacked in sequence; the second battery comprises a second perovskite film, and the third battery comprises a third perovskite film; Wherein, the second perovskite film is prepared by the method according to any one of claims 1 to 7; And / or, the third perovskite film is prepared by the method according to any one of claims 1 to 7.

11. A photovoltaic module, characterized in that: The photovoltaic module at least comprises the perovskite solar cell according to claim 9; And / or, the photovoltaic module at least includes the triple-junction solar cell according to claim 10.

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