Perovskite laminated solar cell, preparation method thereof and photovoltaic module

Abstract

The invention provides a perovskite laminated solar cell and a preparation method thereof, and a photovoltaic module. The preparation method comprises the following steps: providing a perovskite laminated solar cell semi-finished product; performing first annealing treatment on the initial perovskite layer to obtain a pre-crystallized perovskite layer in which original perovskite grains grow; coating a passivating agent solution on the surface of the pre-crystallized perovskite layer and permeating the passivating agent solution to the grain boundary of original perovskite grains; the pre-crystallized perovskite layer permeated with the passivator is subjected to second annealing treatment, a perovskite layer is obtained, and the annealing temperature of the first annealing treatment is lower than the annealing temperature of the second annealing treatment; other functional layers are sequentially prepared on the surface of the perovskite layer to obtain the perovskite laminated solar cell, so that defect recombination at a perovskite internal crystal boundary and a perovskite layer interface is improved, and the photoelectric conversion efficiency and the reliability of the perovskite laminated solar cell are improved.

Description

Technical Field

[0001] This application relates to the field of solar cells, and more particularly to a perovskite tandem solar cell and its preparation method, as well as a photovoltaic module. Background Technology

[0002] Stacked solar cells can further improve the utilization of the solar spectrum, thereby improving the photoelectric conversion efficiency of solar cells.

[0003] In perovskite tandem solar cells, the perovskite layer, a thin film based on perovskite material, is located between the hole transport layer and the electron transport layer and is crucial to the performance of the perovskite tandem solar cell. How to improve the perovskite layer to further enhance its performance, thereby increasing the photoelectric conversion efficiency of the perovskite tandem solar cell, has become an urgent technical problem to be solved. Summary of the Invention

[0004] To address the aforementioned technical problems, this application discloses a perovskite tandem solar cell, its fabrication method, and a photovoltaic module, in order to improve the photoelectric conversion efficiency of the perovskite tandem solar cell.

[0005] In a first aspect, this application provides a method for fabricating a perovskite tandem solar cell, comprising the following steps: A perovskite tandem solar cell semi-finished product is provided, the perovskite tandem solar cell semi-finished product comprising a substrate and a hole transport layer, a hole modification layer and an initial perovskite layer sequentially disposed on the substrate, wherein the initial perovskite layer is obtained based on a vacuum thermal evaporation skeleton and an organic salt solution coating process. The initial perovskite layer is subjected to a first annealing treatment to obtain a pre-crystallized perovskite layer with original perovskite grains growing inside. The passivating agent solution is applied to the surface of the pre-crystallized perovskite layer and penetrates to the grain boundaries of the original perovskite grains; The pre-crystallized perovskite layer impregnated with the passivating agent is subjected to a second annealing treatment to obtain a perovskite layer, wherein the annealing temperature of the first annealing treatment is lower than the annealing temperature of the second annealing treatment. Other functional layers are sequentially fabricated on the surface of the perovskite layer to obtain a perovskite tandem solar cell.

[0006] In some embodiments of this application, the temperature of the first annealing treatment is 60°C to 90°C and the duration is 1 min to 2 min.

[0007] In some embodiments of this application, the temperature of the second annealing treatment is 130°C to 160°C and the duration is 10 min to 20 min.

[0008] In some embodiments of this application, the permeation time of the passivating agent solution is 15s to 20s.

[0009] In some embodiments of this application, the concentration of the passivating agent in the passivating agent solution is 0.5 mg / mL to 2 mg / mL.

[0010] In some embodiments of this application, the passivating agent includes at least one of propylamine chloride, 4-trifluoromethylphenylethylammonium chloride, and 2,3,4,5,6-pentafluorobenzylphosphonic acid.

[0011] Secondly, this application provides a perovskite tandem solar cell, which is prepared by the perovskite tandem solar cell preparation method described in the first aspect.

[0012] In some embodiments of this application, a two-dimensional phase exists both on the surface and inside the perovskite layer.

[0013] In some embodiments of this application, the two-dimensional phase is uniformly distributed on the surface and inside the perovskite layer.

[0014] In some embodiments of this application, the two-dimensional phase is formed from propylamine chloride molecules and / or 4-trifluoromethylphenylethylammonium chloride molecules.

[0015] In some embodiments of this application, the surface of the perovskite layer is sequentially provided with a perovskite passivation layer, an electron transport layer, a buffer layer, a first transparent conductive layer, and an antireflection layer.

[0016] In some embodiments of this application, the substrate includes a bottom battery and a composite layer, and the hole transport layer is disposed on the composite layer.

[0017] In some embodiments of this application, the bottom battery includes at least one of HJT battery, PERC battery, TOPCon battery and IBC battery.

[0018] Thirdly, this application provides a photovoltaic module comprising a solar cell prepared by the method described in the first aspect, or the photovoltaic module comprising a solar cell as described in the second aspect.

[0019] Compared with the prior art, this application has at least the following beneficial effects: This application provides a perovskite tandem solar cell and its fabrication method, as well as a photovoltaic module. By performing a first annealing treatment on the initial perovskite layer, a pre-crystallized perovskite layer with original perovskite grains grown internally is obtained. A passivating agent solution is then coated onto the surface of the pre-crystallized perovskite layer and penetrates to the grain boundaries of the original perovskite grains. This allows for passivation of the perovskite before it has fully pre-crystallized but not yet grown into dense, large grains. Furthermore, the introduction of the passivating agent at this stage does not affect the phase transformation of the perovskite; instead, it passivates along the surface and grain boundaries of the perovskite. Under the combined effect of these factors, the defect recombination at the grain boundaries and perovskite layer interface is improved. In the subsequent fabrication of the perovskite tandem solar cell, this improves the film quality of the perovskite layer and enhances the photoelectric conversion efficiency and reliability of the perovskite tandem solar cell. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of a perovskite tandem solar cell in one embodiment of this application; Figure 2 This is a schematic flowchart of a method for fabricating a perovskite tandem solar cell according to one embodiment of this application; Figure 3 This is a schematic diagram of the structure of a perovskite tandem solar cell in another embodiment of this application.

[0022] Explanation of reference numerals in the attached figures: 1-substrate, 4-perovskite layer, 40-initial perovskite layer, 41-perovskite passivation layer, 5-electron transport layer, 6-buffer layer, 7-first transparent conductive layer, 8-antireflection layer, 11-second transparent conductive layer, 12-P-type doped layer, 13-first intrinsic amorphous silicon layer, 14-crystalline silicon substrate, 15-second intrinsic amorphous silicon layer, 16-N-type doped layer, 17-composite layer, 31-hole transport layer, 32-hole modification layer, 91-positive electrode, 92-back electrode. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0025] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0026] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0027] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0028] The technical solution of this application will be further described below with reference to the embodiments and accompanying drawings.

[0029] In a first aspect, this application provides a method for fabricating a perovskite tandem solar cell, comprising the following steps: Step A: Provide a perovskite tandem solar cell semi-finished product. The perovskite tandem solar cell semi-finished product includes a substrate and a hole transport layer, a hole modification layer and an initial perovskite layer sequentially disposed on the substrate. The initial perovskite layer is obtained based on a vacuum thermal evaporation framework and an organic salt solution coating process. Step B: Perform a first annealing treatment on the initial perovskite layer to obtain a pre-crystallized perovskite layer with original perovskite grains growing inside. Step C: Apply the passivating agent solution to the surface of the pre-crystallized perovskite layer and allow it to penetrate to the grain boundaries of the original perovskite grains; Step D: Perform a second annealing treatment on the pre-crystallized perovskite layer permeated with passivating agent to obtain the perovskite layer. The annealing temperature of the first annealing treatment is lower than the annealing temperature of the second annealing treatment. Step E: Sequentially prepare other functional layers on the surface of the perovskite layer to obtain a perovskite tandem solar cell.

[0030] In step A, refer to Figure 1 The perovskite tandem solar cell semi-finished product includes a substrate 1 and a hole transport layer 31, a hole modification layer 32 and an initial perovskite layer 40 sequentially disposed on the substrate 1. The initial perovskite layer 40 is obtained by vacuum thermal evaporation of the skeleton and coating with an organic salt solution.

[0031] In step B, refer to Figure 2 The initial perovskite layer can be subjected to a first annealing process, which is a pre-crystallization annealing process, thereby obtaining a pre-crystallized perovskite layer with original perovskite grains growing inside. The size and density of these original perovskite grains are lower than those of the grains in the perovskite layer prepared later, which is beneficial for the subsequent infiltration of passivating agents. In step C, refer to Figure 2 The coating process includes, but is not limited to, spin coating. The passivating agent solution contains a dissolved passivating agent, which can be selected from benzene ring passivating agents (e.g., phenylethylamine iodide and its derivatives), long-chain molecular passivating agents (e.g., propylamine iodide, oleylamine iodide, etc.), and hydrophobic molecular passivating agents (e.g., dimethylphenylethyl mercaptoiodide). Among these, long-chain molecular passivating agents and hydrophobic molecular passivating agents can encapsulate and protect the perovskite before annealing, preventing adverse effects of humidity on the perovskite film and improving the stability of the perovskite layer. The solvent for the passivating agent solution can be selected from organic solvents such as isopropanol (IPA) and ethanol (EtOH).

[0032] In step D, refer to Figure 2 This invention provides a second annealing treatment of a pre-crystallized perovskite layer permeated with a passivating agent to obtain a perovskite layer. The annealing temperature of the first annealing treatment is lower than that of the second annealing treatment, which is beneficial for obtaining original perovskite grains with lower size and density after the first annealing treatment, and for allowing the original perovskite grains to grow and become denser after the second annealing treatment, thereby obtaining a perovskite layer.

[0033] In step E, other functional layers include, but are not limited to, a perovskite passivation layer, an electron transport layer, a buffer layer, a first transparent conductive layer, and an antireflection layer.

[0034] The perovskite tandem solar cell and its fabrication method, as well as the photovoltaic module provided in this application, involve performing a first annealing treatment on the initial perovskite layer to obtain a pre-crystallized perovskite layer with original perovskite grains growing inside. A passivating agent solution is then coated onto the surface of the pre-crystallized perovskite layer and penetrates to the grain boundaries of the original perovskite grains. This allows for passivation of the perovskite before it has fully pre-crystallized but not yet grown into dense, large grains. Furthermore, the introduction of the passivating agent at this stage does not affect the phase transformation of the perovskite; it only passivates along the surface and grain boundaries of the perovskite. Under the combined effect of these factors, the defect recombination at the grain boundaries and perovskite layer interface within the perovskite is improved. In the subsequent fabrication of the perovskite tandem solar cell, this improves the film quality of the perovskite layer and enhances the photoelectric conversion efficiency and reliability of the perovskite tandem solar cell.

[0035] In one optional embodiment, the temperature of the first annealing treatment is 60°C to 90°C and the duration is 1 min to 2 min, which is beneficial to obtaining a pre-crystallized perovskite layer with original perovskite grains growing inside.

[0036] In one optional embodiment, the second annealing treatment is performed at a temperature of 130°C to 160°C for a duration of 10 min to 20 min, which is beneficial for the formation of a perovskite layer.

[0037] In one optional embodiment, the permeation time of the passivating agent solution is 15s to 20s, which is beneficial for the passivating agent solution to effectively penetrate to the grain boundaries of the original perovskite grains.

[0038] In one optional embodiment, the concentration of the passivating agent in the passivating agent solution is 0.5 mg / mL to 2 mg / mL, which is beneficial for the complete dissolution of the passivating agent and improves the quality of perovskite film formation.

[0039] In one alternative embodiment, the passivating agent includes at least one of propylammonium chloride (PACl), 4-trifluoromethylphenylethylammonium chloride (4-3F-PEAI), and 2,3,4,5,6-pentafluorobenzylphosphonic acid (p-FBPA).

[0040] Secondly, this application provides a perovskite tandem solar cell, which is prepared by the perovskite tandem solar cell preparation method described in any of the above embodiments.

[0041] In one alternative embodiment, a two-dimensional phase exists both on the surface and inside the perovskite layer. The presence of this two-dimensional phase indicates that the passivating agent can passivate more sites in the perovskite layer, resulting in a better passivation effect.

[0042] In one alternative embodiment, the two-dimensional phase is uniformly distributed on the surface and inside of the perovskite layer, indicating that the passivating agent can passivate both the interface and the grain boundaries inside the perovskite layer simultaneously, resulting in a better passivation effect.

[0043] In one alternative embodiment, the two-dimensional phase is formed by propylamine chloride molecules and / or 4-trifluoromethylphenylethylammonium chloride molecules. In this application, the distribution of the passivating agent molecules in the perovskite layer can be analyzed using X-ray photoelectron spectroscopy (XPS) or interfacial energy dispersive X-ray spectroscopy (EDS) based on characteristic elements in the passivating agent molecules, such as chlorine (Cl) in PACl or fluorine (F) in 4-3F-PEAI.

[0044] In one alternative implementation, see [link to implementation details]. Figure 3 Hole transport layer 31, hole modification layer 32, and perovskite layer 4 are stacked sequentially on composite layer 17. Perovskite passivation layer 41, electron transport layer 5, buffer layer 6, first transparent conductive layer 7, and antireflection layer 8 are sequentially disposed on the surface of perovskite layer 4.

[0045] In one alternative implementation, see [link to implementation details]. Figure 3 The substrate 1 includes a bottom cell 10 and a composite layer 17, and a hole transport layer 31 is disposed on the composite layer 17.

[0046] In one alternative embodiment, the bottom cell includes at least one of a passivated emitter and back contact (PERC) cell, a heterojunction (HJT) cell, a passivated contact (TOPCon) cell, and an all-back electrode contact (IBC) cell.

[0047] In one alternative implementation, see [link to implementation details]. Figure 3 The bottom cell 10 includes, from bottom to top, a second transparent conductive layer 11, a P-type doped layer 12, a first intrinsic amorphous silicon layer 13, a crystalline silicon substrate 14, a second intrinsic amorphous silicon layer 15, and an N-type doped layer 16.

[0048] In preparing the perovskite layer, this application first prepares a PbI2 framework layer by vacuum thermal evaporation, and then coats it with an organic salt via solution method to react and form the perovskite. The first step is mainly evaporation, and the second step is completed by spin coating, blade coating, or slot coating. The framework layer can be obtained by evaporating PbI2 and CsX (X represents a halogen element). This application does not particularly limit the type of organic salt. For example, at least two of formamidine hydroiodide (FAI), formamidine hydrobromide (FABr), formamidine hydrochloride (FACl), methylamine iodide (MAI), methylamine bromide (MABr), and methylamine chloride (MACl) can be dissolved in a solvent to obtain a perovskite precursor liquid. The thickness of the perovskite layer is 400 nm to 1000 nm. The surface of the perovskite layer may also include a perovskite passivation layer. The composite layer can be formed based on physical vapor deposition (PVD) or reactive plasma deposition (RPD) processes. The material of the composite layer may include, but is not limited to, indium tin oxide (ITO) and indium zinc oxide (IZO), with a thickness of 20 nm to 30 nm. The hole transport layer can be formed based on PVD or CVD processes, with a thickness of 10 nm to 30 nm. The material of the hole transport layer includes, but is not limited to, nickel oxide (NiO). x Inorganic hole transport materials such as molybdenum trioxide (MoO3) or vanadium pentoxide (V2O5), or organic materials such as Spiro-TTB, can be used. Hole-modifying layers can be formed using spin coating, slot coating, or other processes. These layers include self-assembled monolayer (SAM) materials, such as (2-(9H-carbazole-9-yl)ethyl)phosphonic acid (2PACz) or (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (4PACz), with a concentration of 0.5 mg / mL to 2 mg / mL. Spin coating is used at a speed of 3000 rpm to 5000 rpm, an annealing temperature of 80℃ to 120℃, and an annealing time of 10 min to 15 min. Buffer layers can be prepared from SnO2 using atomic layer deposition (ALD) equipment, with a thickness of 10 nm to 30 nm. nm; The first transparent conductive layer can be prepared from indium tin oxide (ITO) using magnetron sputtering (PVD) equipment, with a thickness of 30 nm to 100 nm.

[0049] For the bottom cell, the thickness of the crystalline silicon substrate can be 60 μm to 400 μm; the first intrinsic amorphous silicon layer can be formed by chemical vapor deposition (CVD); the second intrinsic amorphous silicon layer can be formed by chemical vapor deposition (CVD); the N-type doped layer can be formed by CVD, with a thickness of 5 nm to 30 nm, and is doped with N-type doping elements, such as phosphorus; the P-type doped layer can be formed by CVD, with a thickness of 5 nm to 30 nm, and is doped with P-type doping elements, such as boron; the second transparent conductive layer can be formed by PVD, with a thickness of 30 nm to 100 nm.

[0050] In addition, the electrode material Ag can be thermally evaporated and deposited to obtain the positive electrode and the back electrode, with an electrode thickness of 100 nm to 500 nm. An antireflection layer can also be prepared on the positive electrode. The antireflection layer can be prepared by evaporation process, and the material can be MgF2 or LiF with a thickness of 80 nm to 120 nm.

[0051] This application does not impose any particular restrictions on the electrodes of the solar cell, as long as they achieve the purpose of this application. For example, see reference... Figure 1 and Figure 2 A positive electrode 91 can be disposed on the light-receiving surface of the solar cell, and a back electrode 92 can be disposed on the back surface of the solar cell. This application does not impose any particular restrictions on the materials of the positive and back electrodes, including but not limited to silver (Ag), copper (Cu), aluminum (Al), etc., with a thickness of 150 nm to 300 nm.

[0052] The perovskite tandem solar cell of this application improves the defects in the perovskite layer, including the internal grain boundaries of the titanium dioxide and the interface of the perovskite layer. This results in a higher film quality for the perovskite film and enhances the photoelectric conversion efficiency and reliability of the perovskite tandem solar cell.

[0053] Thirdly, this application provides a photovoltaic module comprising a solar cell prepared by the preparation method described in the first aspect, or the photovoltaic module comprising a solar cell as described in the second aspect.

[0054] This application also provides a photovoltaic module for converting received light energy into electrical energy and transmitting it to an external load. The photovoltaic module includes: at least one cell string, which is composed of multiple solar cells connected together; an encapsulating film for covering the surface of the cell string; and a cover plate for covering the surface of the encapsulating film facing away from the cell string.

[0055] Example The solar cells, their fabrication methods, and photovoltaic modules of this application will be further described below with reference to more specific embodiments.

[0056] Example 1 <Substrate Preparation> A textured HJT bottom cell (2.5cm × 2.5cm) is provided, and an FTO thin film with a thickness of approximately 30nm is prepared on the light-receiving surface of the bottom cell using a PVD device as a composite layer to obtain the substrate. The bottom cell, from bottom to top, comprises a second transparent conductive layer with a thickness of approximately 100 nm, a P-type doped layer with a thickness of approximately 10 nm, a first intrinsic amorphous silicon layer with a thickness of approximately 7 nm, an N-type silicon wafer (i.e., a crystalline silicon substrate) with a thickness of approximately 120 μm, a second intrinsic amorphous silicon layer with a thickness of approximately 7 nm, and an N-type doped layer with a thickness of approximately 6 nm. <Preparation of Hole Transport Layer> A NiO layer with a thickness of approximately 20 nm was deposited on the surface of the composite layer using a PVD device. X Hole transport layer; <Preparation of Hole Modification Layer> A SAM film layer was prepared on the surface of the hole transport layer as a hole modification layer, and the SAM material was 2PACz. <Preparation of Perovskite Layer> First, a PbI₂+60 nm thick CsBr framework layer was prepared. The second step involved spin-coating an organic salt solution. The organic salt solution consisted of 40 mg formamidin hydroiodate (FAI), 12 mg methylamine bromide (MABr), and 12 mg methylamine chloride (MACl), dissolved in 1 mL of anhydrous ethanol. After complete dissolution, 100 μL of the solution was dropped onto the framework layer and dynamically spin-coated at 4000 rpm for 20 minutes. The initial perovskite layer was obtained by spin-coating the pre-crystallized perovskite film at 70°C for 1 min. Then, a 1 mg / mL solution of the passivating agent 4-trifluoromethylphenylethylammonium chloride (4-3F-PEAI) was spin-coated onto the pre-crystallized perovskite film at 4000 rpm for 20 s to allow the passivating agent to penetrate the perovskite film. Finally, the pre-crystallized perovskite layer with the passivating agent was subjected to a second annealing treatment at 150°C for 15 min to complete the perovskite grain growth, resulting in the perovskite layer. <Preparation of Perovskite Passivation Layer> A perovskite passivation layer was prepared on the perovskite light-absorbing layer by a solution method. The passivation molecule was ethylenediamine dihydroiodide (EDAI2). The spin coating rate was 3000 rpm and the annealing time was 10 mins to obtain the perovskite passivation layer. <Preparation of Electron Transport Layer> A C layer with a thickness of approximately 20 nm was deposited on the perovskite passivation layer. 60 The film layer serves as an electron transport layer; <Preparation of the buffer layer> A SnO2 film with a thickness of about 20 nm was prepared on the electron transport layer using the ALD process as a buffer layer. <Preparation of the first transparent electrode layer> An IZO film with a thickness of approximately 100 nm was prepared on the electron transport layer using a PVD process as the first transparent electrode layer. <Electrode Preparation> A positive electrode made of silver is prepared by thermal evaporation on a first transparent electrode layer, and a back electrode made of silver is prepared by thermal evaporation on a second transparent electrode layer.

[0057] <Preparation of Antireflective Layer> An antireflection layer with a thickness of 100 nm was obtained by thermal evaporation deposition of LiF using a metal evaporation device.

[0058] Examples 2-3 Except for adjusting the type of passivating agent according to Table 1 in the <Preparation of Perovskite Layer> section, the rest is the same as in Example 1.

[0059] Examples 4-5 Except for adjusting the temperature of the first annealing treatment according to Table 1 in the <Preparation of Perovskite Layer> section, the rest is the same as in Example 1.

[0060] Examples 6-7 Except for adjusting the temperature of the second annealing treatment according to Table 1 in the <Preparation of Perovskite Layer>, the rest is the same as in Example 1.

[0061] Examples 8-9 Except for adjusting the concentration of the passivating agent in the passivating agent solution according to Table 1 in the <Preparation of Perovskite Layer> section, the rest is the same as in Example 1.

[0062] Example 10 Except for adjusting the permeation time of the passivating agent solution according to Table 1 in the <Preparation of Perovskite Layer> section, the rest is the same as in Example 1.

[0063] Comparative Example 1 Except for the preparation of the perovskite layer, which is different from Example 1, everything else is the same as Example 1.

[0064] The preparation steps of the perovskite layer are as follows: First, a PbI2+60 nm thick CsBr framework layer was prepared. In the second step, an organic salt solution was spin-coated. The organic salt solution was formulated as follows: 40 mg formamidin hydroiodide (FAI), 12 mg methylamine bromide (MABr), and 12 mg methylamine chloride (MACl) were dissolved in 1 mL of anhydrous ethanol. After complete dissolution, 100 μL of the solution was dropped onto the framework layer and dynamically spin-coated at a speed of 4000 rpm for 20 s. Subsequently, the layer was placed on a hot metal plate at 150 °C for annealing for 15 min to complete the perovskite grain growth.

[0065] Comparative Example 2 Except for adjusting the temperature of the first annealing treatment according to Table 1 in the <Preparation of Perovskite Layer>, the rest is the same as in Example 1.

[0066] Table 1: Preparation parameters for each example and comparative example

[0067] In Table 1, " / " indicates that no relevant preparation parameters exist.

[0068] Performance testing: Open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency tests: The current (I)-voltage (V) of the solar cells in each embodiment and comparative example were measured using an IV tester (manufacturer: Wavelabs) to obtain the open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency of the solar cells.

[0069] Table 2: Performance data of each embodiment and comparative example

[0070] As can be seen from Examples 1 to 10 and Comparative Example 1, when the perovskite layer is not pre-crystallized (e.g., Comparative Example 1), the open-circuit voltage, fill factor, and photoelectric conversion efficiency of the prepared perovskite tandem solar cell are all low. This may be because the perovskite layer in Comparative Example 1 was not pre-crystallized, resulting in a generally poor perovskite film quality. When the pre-crystallization temperature is too high (e.g., Comparative Example 2), the open-circuit voltage, fill factor, and photoelectric conversion efficiency of the prepared perovskite tandem solar cell are all low. This may be because the excessively high pre-crystallization temperature causes the original small grains to undergo initial grain boundary fusion and grow into large grains, reducing the grain boundaries and hindering the penetration of subsequent passivation molecules, resulting in a generally poor perovskite film quality. However, the open-circuit voltage, fill factor, and photoelectric conversion efficiency of the perovskite tandem solar cell of this application are all improved.

[0071] The type of passivating agent, the temperature of the first annealing treatment, the temperature of the second annealing treatment, the concentration of the passivating agent, and the penetration time of the passivating agent usually also affect the performance of the perovskite layer. As can be seen from Examples 1 to 11, by adjusting the above preparation parameters within the scope of this application, it is beneficial to obtain perovskite tandem solar cells with good performance.

[0072] The above provides a detailed description of a perovskite tandem solar cell, its fabrication method, and photovoltaic module disclosed in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core inventive points of the embodiments of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for fabricating a perovskite tandem solar cell, characterized in that, Includes the following steps: A perovskite tandem solar cell semi-finished product is provided, the perovskite tandem solar cell semi-finished product comprising a substrate and a hole transport layer, a hole modification layer and an initial perovskite layer sequentially disposed on the substrate, wherein the initial perovskite layer is obtained based on a vacuum thermal evaporation skeleton and an organic salt solution coating process. The initial perovskite layer is subjected to a first annealing treatment to obtain a pre-crystallized perovskite layer with original perovskite grains growing inside. The passivating agent solution is applied to the surface of the pre-crystallized perovskite layer and penetrates to the grain boundaries of the original perovskite grains; The pre-crystallized perovskite layer impregnated with the passivating agent is subjected to a second annealing treatment to obtain a perovskite layer, wherein the annealing temperature of the first annealing treatment is lower than the annealing temperature of the second annealing treatment. Other functional layers are sequentially fabricated on the surface of the perovskite layer to obtain a perovskite tandem solar cell.

2. The method for preparing a perovskite tandem solar cell according to claim 1, characterized in that, The temperature of the first annealing treatment is 60℃~90℃ and the duration is 1min~2min.

3. The method for preparing a perovskite tandem solar cell according to claim 1, characterized in that, The second annealing treatment is performed at a temperature of 130℃~160℃ for a duration of 10min~20min.

4. The method for preparing a perovskite tandem solar cell according to claim 1, characterized in that, The permeation time of the passivating agent solution is 15s~20s.

5. The method for preparing a perovskite tandem solar cell according to claim 1, characterized in that, The concentration of the passivating agent in the passivating agent solution is 0.5 mg / mL to 2 mg / mL.

6. The method for preparing a perovskite tandem solar cell according to claim 1, characterized in that, The passivating agent includes at least one of propylamine chloride, 4-trifluoromethylphenylethylammonium chloride, and 2,3,4,5,6-pentafluorobenzylphosphonic acid.

7. A perovskite tandem solar cell, characterized in that, The perovskite tandem solar cell is prepared by the method described in any one of claims 1 to 6.

8. The perovskite tandem solar cell according to claim 7, characterized in that, The perovskite layer contains two-dimensional phases on both its surface and interior.

9. The perovskite tandem solar cell according to claim 8, characterized in that, The two-dimensional phase is uniformly distributed on the surface and inside the perovskite layer.

10. The perovskite tandem solar cell according to claim 8, characterized in that, The two-dimensional phase is formed by propylamine chloride molecules and / or 4-trifluoromethylphenylethylammonium chloride molecules.

11. The perovskite tandem solar cell according to claim 7, characterized in that, The surface of the perovskite layer is sequentially provided with a perovskite passivation layer, an electron transport layer, a buffer layer, a first transparent conductive layer, and an antireflection layer.

12. The perovskite tandem solar cell according to claim 7, characterized in that, The substrate includes a bottom battery and a composite layer, and the hole transport layer is disposed on the composite layer.

13. The perovskite tandem solar cell according to claim 12, characterized in that, The bottom battery includes at least one of HJT battery, PERC battery, TOPCon battery and IBC battery.

14. A photovoltaic module, characterized in that, The photovoltaic module comprises a solar cell prepared by the preparation method according to any one of claims 1 to 6, or the photovoltaic module comprises a solar cell according to any one of claims 7 to 13.

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