Solar cell, preparation method thereof and photovoltaic module

Abstract

The invention provides a solar cell and a preparation method thereof, and a photovoltaic module, the solar cell comprises a substrate, and a hole transport layer, a perovskite layer, a passivation layer and an electron transport layer which are sequentially arranged on the substrate, and the passivation layer is located between the perovskite layer and the electron transport layer; and the passivation layer comprises a mercaptopyridine compound and ethanediamine diiodide, so that the surface defects of the perovskite layer are reduced, and the interface recombination of the top interface between the perovskite layer and the electron transport layer is reduced, thereby improving the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

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

[0002] Perovskite solar cells are devices that convert solar energy into electrical energy. They have excellent photoelectric properties and are simple in structure and low in manufacturing cost.

[0003] In perovskite solar cells, the perovskite layer plays a crucial role in the photoelectric conversion performance of the solar cell. How to passivate the interface of the perovskite layer to reduce interface defects and thus improve the photoelectric conversion efficiency of the perovskite 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 solar cell and its fabrication method, as well as a photovoltaic module, to improve the photoelectric conversion efficiency of perovskite solar cells.

[0005] In a first aspect, this application provides a solar cell, including a substrate and a hole transport layer, a perovskite layer, a passivation layer and an electron transport layer sequentially disposed on the substrate, wherein the passivation layer is located between the perovskite layer and the electron transport layer; the passivation layer includes a mercaptopyridine compound and ethylenediamine diiodide.

[0006] In some embodiments of this application, the mass percentage of mercaptopyridine compounds in the passivation layer is a, 50% ≤ a ≤ 80%, and the mass percentage of ethylenediamine diiodide in the passivation layer is b, 20% ≤ b ≤ 50%.

[0007] In some embodiments of this application, 60% ≤ a ≤ 70%, and 30% ≤ b ≤ 40%.

[0008] In some embodiments of this application, the mercaptopyridine compound is selected from at least one of the following compounds:

[0009]

[0010] In some embodiments of this application, the structural formula of the ethylenediamine diiodide is:

[0011]

[0012] In some embodiments of this application, the solar cell includes a perovskite tandem solar cell, the substrate includes a base cell and a composite layer stacked on the base cell, the hole transport layer, the perovskite layer, the passivation layer and the electron transport layer are sequentially stacked on the composite layer, and the surface of the composite layer facing the hole transport layer has a textured surface.

[0013] In some embodiments of this application, a buffer layer, a first transparent electrode layer, and an antireflection layer are also stacked sequentially on the electron transport layer.

[0014] Secondly, this application provides a method for fabricating a solar cell as described in the first aspect, comprising the following steps:

[0015] A substrate is provided, and a hole transport layer and a perovskite layer are sequentially formed on the surface of the composite layer of the substrate;

[0016] A passivation layer is prepared on the perovskite layer, the passivation layer containing a mercaptopyridine compound and ethylenediamine diiodide;

[0017] Other functional layers are sequentially prepared on the surface of the passivation layer, and the other functional layers include at least an electron transport layer.

[0018] In some embodiments of this application, the process of preparing the passivation layer includes:

[0019] A mercaptopyridine compound and ethylenediamine diiodide are dissolved in a first solvent to form a passivation layer precursor solution;

[0020] The passivation layer precursor liquid is coated on the surface of the perovskite layer, and the passivation layer is formed after annealing.

[0021] In some embodiments of this application, the concentration of mercaptopyridine compounds in the passivation layer precursor solution is 0.7 mg / mL to 1.3 mg / mL, and the concentration of ethylenediamine diiodide in the passivation layer precursor solution is 0.3 mg / mL to 0.8 mg / mL.

[0022] In some embodiments of this application, the process of preparing the passivation layer includes:

[0023] A mercaptopyridine compound is dissolved in a first solvent to form a first solution;

[0024] Ethylenediamine diiodide is dissolved in a second solvent to form a second solution;

[0025] The first solution is coated on the surface of the perovskite layer, and after a first annealing treatment, an initial film structure is formed.

[0026] The second solution is applied to the surface of the initial film structure to fill the areas not completely covered by mercaptopyridine compounds in the initial film structure with ethylenediamine diiodide. After a second annealing treatment, the passivation layer is formed.

[0027] In some embodiments of this application, the concentration of the mercaptopyridine compound in the first solution is 1.4 mg / mL to 1.6 mg / mL, and the concentration of the ethylenediamine diiodide in the second solution is 0.6 mg / mL to 0.8 mg / mL.

[0028] In some embodiments of this application, the first solvent includes methanol and the second solvent includes isopropanol.

[0029] Thirdly, this application provides a photovoltaic module, which includes a solar cell as described in the first aspect, or the photovoltaic module includes a solar cell prepared by the preparation method described in the second aspect.

[0030] Compared with the prior art, this application has at least the following beneficial effects:

[0031] This application provides a solar cell and its fabrication method, as well as a photovoltaic module. The solar cell includes a substrate and a hole transport layer, a perovskite layer, a passivation layer, and an electron transport layer sequentially disposed on the substrate. The passivation layer is located between the perovskite layer and the electron transport layer, and includes a mercaptopyridine compound and ethylenediamine diiodide. Through the synergistic effect of the mercaptopyridine compound and ethylenediamine diiodide, the surface defects of the perovskite layer are reduced, while the interfacial recombination at the top interface between the perovskite layer and the electron transport layer is reduced, thereby improving the photoelectric conversion efficiency of the solar cell. Attached Figure Description

[0032] 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.

[0033] Figure 1 This is a schematic diagram of the structure of a solar cell in one embodiment of this application;

[0034] Figure 2 This is a schematic diagram of the structure of a solar cell in another embodiment of this application.

[0035] Explanation of reference numerals in the attached figures: Substrate-1, Hole transport layer-2, Perovskite layer-3, Passivation layer-4, Electron transport layer-5, Buffer layer-6, First transparent electrode layer-7, Anti-reflection layer-8, Bottom cell-10, Second transparent electrode layer-11, P-type doped crystalline silicon layer-12, First intrinsic amorphous silicon layer-13, N-type silicon wafer-14, Second intrinsic amorphous silicon layer-15, N-type doped crystalline silicon layer-16, Composite layer-17, Positive electrode-91, Back electrode-92. Detailed Implementation

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (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, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0041] The technical solution of this application will be further described below with reference to the embodiments and accompanying drawings.

[0042] Firstly, this application provides a solar cell, such as Figure 1 As shown, the solar cell includes a substrate 1 and a hole transport layer 2, a perovskite layer 3, a passivation layer 4 and an electron transport layer 5 sequentially disposed on the substrate 1. The passivation layer 4 includes a mercaptopyridine compound and ethylenediamine diiodide.

[0043] The inventors discovered that by applying both mercaptopyridine compounds and ethylenediamine diiodide to the passivation layer, the photoelectric conversion efficiency of solar cells was significantly improved. This is likely because the mercaptopyridine compounds contain both a pyridine ring and a mercapto group, and both the nitrogen atom in the pyridine ring and the sulfur atom in the mercapto group can react with the Pb in the perovskite layer. 2+ This combination allows nitrogen and sulfur atoms to be linked together, creating a bidental anchoring effect. This enhances the bonding strength and adhesion of mercaptopyridine compounds to the perovskite layer surface, thereby reducing surface defects in the perovskite layer. The ethylenediamine diiodide molecule contains two -NH groups. 3+ Group, one of which is -NH 3+ The group is anchored on the surface of the perovskite layer, another -NH 3+ The groups extending from the surface of the perovskite layer generate a dipole effect, reducing interfacial recombination at the top interface between the perovskite layer and the electron transport layer through field-effect passivation. Thus, mercaptopyridine compounds and ethylenediamine diiodide work synergistically to reduce both surface defects in the perovskite layer and interfacial recombination at the top interface between the perovskite layer and the electron transport layer, thereby improving the photoelectric conversion efficiency of the solar cell.

[0044] In one optional embodiment, the mass percentage of mercaptopyridine compounds in the passivation layer is 'a', 50% ≤ a ≤ 80%, and the mass percentage of ethylenediamine diiodide in the passivation layer is 'b', 20% ≤ b ≤ 50%. In another optional embodiment, 60% ≤ a ≤ 70% and 30% ≤ b ≤ 40%. By controlling the content of mercaptopyridine compounds within the above ranges, it is more advantageous to obtain perovskite solar cells with excellent photoelectric conversion efficiency.

[0045] In one alternative embodiment, the mercaptopyridine compound is selected from at least one of the following compounds:

[0046]

[0047] In one alternative embodiment, the structural formula of ethylenediamine diiodide (EDAI2) is:

[0048]

[0049] This application does not impose any particular limitation on the thickness of the passivation layer, which can be a nanometer-scale film with a thickness of 1 to 5 molecules. For example, the thickness of the passivation layer is 0.5 nm to 2 nm.

[0050] In one alternative implementation, refer to Figure 1 The solar cell includes a perovskite tandem solar cell. The substrate 1 includes a base cell 10 and a composite layer 17 stacked on the base cell 10. A hole transport layer 2, a perovskite layer 3, a passivation layer 4, and an electron transport layer 5 are sequentially stacked on the composite layer 17. The surface of the composite layer 17 facing the hole transport layer 2 has a textured surface. The base cell 10, from bottom to top, includes a second transparent electrode layer 11, a P-type doped crystalline silicon layer 12, a first intrinsic amorphous silicon layer 13, an N-type silicon wafer 14, a second intrinsic amorphous silicon layer 15, and an N-type doped crystalline silicon layer 16. Furthermore, a first transparent electrode layer 7 is also provided on the electron transport layer 5.

[0051] The substrate of this application can be a solar cell based on a crystalline silicon substrate, and this application is not limited thereto. To better absorb solar energy, the composite layer of this application has a textured structure on the surface facing the hole transport layer (i.e., the light incident surface). For example, this textured structure can be a pyramid-shaped textured structure. This textured structure provides a higher surface area for the solar cell while reducing light reflection and diffusion. The surface of the hole transport layer and the textured structure of the composite layer have the same shape, both being pyramid-shaped, thus achieving the shape retention requirement of the textured structure. This application does not particularly limit the preparation method of the textured structure, as long as it achieves the purpose of this application; for example, it can be prepared using existing wet etching processes.

[0052] In one alternative implementation, refer to Figure 2 Furthermore, a buffer layer 6, a first transparent electrode layer 7, and an antireflection layer 8 are sequentially stacked on the electron transport layer 5. The buffer layer 6 is located on the surface of the electron transport layer 5 opposite to the passivation layer 4 (i.e., the light incident surface), and the antireflection layer 8 is located on the surface of the first transparent electrode layer 7 opposite to the buffer layer 6. Solar cells containing the aforementioned antireflection layer have higher photoelectric conversion efficiency.

[0053] 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 set on the light-receiving surface of the solar cell, and a back electrode 92 can be set on the back surface of the solar cell.

[0054] The hole transport layer, perovskite layer, passivation layer, and electron transport layer of this application can also be applied to single-junction perovskite solar cells. This application does not impose any particular restrictions on the structure of single-junction perovskite solar cells; any existing single-junction perovskite solar cell structure can be used.

[0055] Secondly, this application provides a method for fabricating a solar cell as described in the first aspect, comprising the following steps:

[0056] Step A: Provide a substrate, and sequentially prepare a hole transport layer and a perovskite layer on the surface of the composite layer of the substrate;

[0057] Step B: Prepare a passivation layer on the perovskite layer, the passivation layer containing mercaptopyridine compounds and ethylenediamine diiodide;

[0058] Step C: Sequentially prepare other functional layers on the surface of the passivation layer, the other functional layers including at least an electron transport layer.

[0059] In step A, the hole transport layer can be prepared by magnetron sputtering and / or spin coating. When preparing the perovskite layer, a framework layer can be prepared first, and then an organic salt solution can be spin-coated onto the surface of the framework layer, followed by thermal annealing to obtain the perovskite layer. The framework layer can be obtained by vapor deposition of PbI2 and CsX (X representing 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 an organic salt solution. This application does not particularly limit the coating method; for example, spin coating, spray coating, slot coating, and blade coating can be used. The thickness of the perovskite layer is 400 nm to 500 nm.

[0060] In step B, in one optional embodiment, the passivation layer can be prepared by a mixed deposition method, that is, by coating a solution containing a mercaptopyridine compound and ethylenediamine diiodide onto the surface of the perovskite layer to prepare the passivation layer; or, in another optional embodiment, the passivation layer can be prepared by a sequential deposition method, that is, by first coating a solution containing a mercaptopyridine compound onto the surface of the perovskite layer, and after the film is formed, coating a solution containing ethylenediamine diiodide onto the surface of the formed film to prepare the passivation layer.

[0061] In step C, other functional layers may also include a buffer layer, a first transparent electrode layer, and an antireflection layer.

[0062] In one optional embodiment, a hybrid deposition method is used to prepare the passivation layer, the preparation process of which includes:

[0063] Step a: Dissolve mercaptopyridine compounds and ethylenediamine diiodide in a first solvent to form a passivation layer precursor solution;

[0064] Step b: Apply a passivation layer precursor liquid to the surface of the perovskite layer, and form a passivation layer after annealing.

[0065] In step a, the concentration of mercaptopyridine compounds in the passivation layer precursor solution can be 0.7 mg / mL to 1.3 mg / mL, and the concentration of ethylenediamine diiodide in the passivation layer precursor solution can be 0.3 mg / mL to 0.8 mg / mL; the first solvent includes, but is not limited to, methanol.

[0066] In step b, the coating method can be spin coating, the annealing temperature is 90℃~110℃, and the annealing time is 4min~6min. A mixed deposition method is used to form the passivation layer. In the prepared passivation layer, the distribution of mercaptopyridine compounds and ethylenediamine diiodide is relatively uniform, and the passivation layer has a good passivation effect.

[0067] In another alternative embodiment, the passivation layer is prepared by sequential deposition, and the preparation process includes:

[0068] Step i: Dissolve the mercaptopyridine compound in the first solvent to form the first solution;

[0069] Step ii: Dissolve ethylenediamine diiodide in a second solvent to form a second solution;

[0070] Step iii: Coat the surface of the perovskite layer with the first solution, and perform the first annealing treatment to form the initial film structure;

[0071] Step iv: A second solution is applied to the surface of the initial film structure to allow ethylenediamine diiodide to fill the areas not completely covered by mercaptopyridine compounds in the initial film structure. After a second annealing treatment, a passivation layer is formed.

[0072] In step i, the concentration of the mercaptopyridine compound in the first solution can be 1.4 mg / mL to 1.6 mg / mL; the first solvent includes, but is not limited to, methanol.

[0073] In step ii, the concentration of ethylenediamine diiodide in the second solution can be 0.6 mg / mL to 0.8 mg / mL; the second solvent includes, but is not limited to, isopropanol.

[0074] In step iii, the coating method can be spin coating, and the temperature of the first annealing treatment is 90℃~110℃, and the time is 4min~6min. The coating amount of the second solution can be the same as or different from that of the first solution.

[0075] In step iv, the coating method can be spin coating, and the temperature of the second annealing treatment is 90℃~110℃ and the time is 4min~6min. A passivation layer is formed by sequential deposition. In the prepared passivation layer, ethylenediamine diiodide can fill the areas not completely covered by mercaptopyridine compounds in the initial film structure, and the passivation layer has a good passivation effect.

[0076] In one alternative implementation, the fabrication process of other functional layers includes:

[0077] An electron transport layer, a buffer layer, a first transparent electrode layer, and an antireflection layer are sequentially fabricated on the surface of the passivation layer.

[0078] This application does not impose any particular limitations on the fabrication methods of the electron transport layer, buffer layer, first transparent electrode layer, antireflection layer, and electrodes. For example, the electron transport layer material C can be used. 60 An electron transport layer with a thickness of 10 nm to 20 nm can be obtained by thermal evaporation deposition using a metal evaporation device; a buffer layer with a thickness of 10 nm to 17 nm can be prepared using atomic layer deposition (ALD) using tin dioxide (SnO2) as the buffer layer material; a first transparent electrode layer with a thickness of 70 nm to 110 nm can be prepared using indium gallium zinc oxide (IZO) as the transparent electrode layer material using magnetron sputtering (PVD); an antireflection layer with a thickness of 80 nm to 130 nm can be obtained by thermal evaporation deposition using LiF or MgF2 as the antireflection layer material; and positive and back electrodes with an electrode thickness of 300 nm to 500 nm can be obtained by thermal evaporation deposition using Ag as the electrode material.

[0079] The method for fabricating a solar cell provided in this application has the advantages of simple fabrication process and convenient operation, which is conducive to industrial production and suitable for large-scale manufacturing of perovskite-silicon tandem solar cells. Furthermore, when the prepared passivation layer is applied to the perovskite-silicon tandem solar cell, it reduces the surface defects of the perovskite layer and the interfacial recombination at the top interface between the perovskite layer and the electron transport layer, thereby improving the photoelectric conversion efficiency of the perovskite-silicon tandem solar cell.

[0080] Thirdly, this application provides a photovoltaic module, which includes a solar cell as described in the first aspect, or the photovoltaic module includes a solar cell prepared by the preparation method described in the second aspect.

[0081] 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.

[0082] Example

[0083] The solar cells, their fabrication methods, and photovoltaic modules of this application will be further described below with reference to more specific embodiments.

[0084] Example 1

[0085] <Substrate Preparation>

[0086] A textured base cell is provided, and a 20 nm thick indium tin oxide (ITO) film is prepared on the light-receiving surface of the base cell as a composite layer to obtain the substrate. The base cell, from bottom to top, comprises a second transparent electrode layer with a thickness of 100 nm, a P-type doped crystalline silicon layer with a thickness of 10 nm, a first intrinsic amorphous silicon layer with a thickness of 7 nm, an N-type silicon wafer with a thickness of 120 μm, a second intrinsic amorphous silicon layer with a thickness of 7 nm, and an N-type doped crystalline silicon layer with a thickness of 6 nm.

[0087] <Preparation of Hole Transport Layer>

[0088] The substrate was placed on the carrier plate of the magnetron sputtering equipment, and a NiO layer with a thickness of 20 nm was deposited on the surface of the ITO composite layer of the substrate. X Hole transport layer, forming a hole transport layer.

[0089] <Preparation of Perovskite Layer>

[0090] A perovskite layer with a thickness of 450 nm was prepared on the surface of the hole transport layer by co-evaporation.

[0091] <Preparation of Passivation Layer>

[0092] A mercaptopyridine compound (compound of formula (I-1)) and ethylenediamine diiodide were dissolved in methanol to form a passivation layer precursor solution. The concentration of the mercaptopyridine compound in the passivation layer precursor solution was 1.2 mg / mL, and the concentration of ethylenediamine diiodide in the passivation layer precursor solution was 0.7 mg / mL. Then, 100 μL of the passivation layer precursor solution was measured and coated onto the surface of the perovskite layer by spin coating. After annealing, a passivation layer was obtained at 100 °C for 5 min. The mass percentages of the mercaptopyridine compound and ethylenediamine diiodide in the passivation layer are shown in Table 1.

[0093] <Preparation of other functional layers>

[0094] An electron transport layer, a buffer layer, and a first transparent electrode layer are sequentially prepared on the surface of the passivation layer.

[0095] The electron transport layer is fabricated by depositing a 20nm thick C layer on the perovskite layer. 60As an electron transport layer;

[0096] The preparation process of the buffer layer is as follows: a 10 nm thick SnO2 layer is prepared on the electron transport layer using atomic layer deposition as a buffer layer;

[0097] The fabrication process of the first transparent electrode layer is as follows: a 100 nm thick layer of IZO is prepared on the electron transport layer by magnetron sputtering as the first transparent electrode layer.

[0098] <Solar Cell Fabrication>

[0099] A 350 nm thick silver layer was thermally evaporated onto the first transparent electrode layer as the positive electrode. A 300 nm thick silver layer was thermally evaporated onto the second transparent electrode layer of the bottom cell as the back electrode. Then, a 100 nm thick anti-reflection layer was deposited by thermal evaporation of LiF using a metal evaporation device, resulting in the solar cell. The cell structure is as follows. Figure 2 As shown.

[0100] Examples 2 to 5

[0101] Except for the section on "Preparation of Passivation Layer", where the concentrations of mercaptopyridine compounds and ethylenediamine diiodide in the passivation layer precursor solution are adjusted according to Table 1, thus changing the relative contents of mercaptopyridine compounds and ethylenediamine diiodide in the passivation layer, the rest is the same as in Example 1.

[0102] Examples 6 to 7

[0103] Except for adjusting the types of mercaptopyridine compounds according to Table 1 in the <Preparation of Passivation Layer> section, the rest is the same as in Example 1.

[0104] Example 8

[0105] Except for the preparation of the passivation layer, which uses a sequential deposition method, the rest is the same as in Example 1. The specific preparation process is as follows:

[0106] A mercaptopyridine compound (compound of formula (I-1)) was dissolved in methanol to form a first solution with a concentration of 1.5 mg / mL. Ethylenediamine diiodide was dissolved in isopropanol to form a second solution with a concentration of 0.7 mg / mL. 100 μL of the first solution was then spin-coated onto the surface of the perovskite layer. After a first annealing treatment at 100 °C for 5 min, an initial film structure was formed. Another 100 μL of the second solution was spin-coated onto the surface of the initial film structure. After a second annealing treatment at 100 °C for 5 min, a passivation layer was formed. The mass percentages of the mercaptopyridine compound and ethylenediamine diiodide in the passivation layer are shown in Table 2.

[0107] Examples 9 to 10

[0108] Except for the section on "Preparation of Passivation Layer", which adjusts the concentrations of mercaptopyridine compounds in the first solution and ethylenediamine diiodide in the second solution according to Table 2, thereby changing the relative contents of mercaptopyridine compounds and ethylenediamine diiodide in the passivation layer, the rest is the same as in Example 8.

[0109] Comparative Example 1

[0110] Except for the fact that the passivation layer precursor solution contains only mercaptopyridine compounds in the <Preparation of Passivation Layer> section, the rest is the same as in Example 1.

[0111] Comparative Example 2

[0112] Except for the fact that the passivation layer precursor solution contains only ethylenediamine diiodide in the <Preparation of Passivation Layer> section, the rest is the same as in Example 1.

[0113] Table 1. Preparation parameters of Examples 1-7 and Comparative Examples 1-2

[0114]

[0115] In Table 1, " / " indicates that no relevant preparation parameters exist.

[0116] Table 2 Preparation parameters of Examples 8 to 10

[0117]

[0118]

[0119] Performance testing:

[0120] Open-circuit voltage, short-circuit current density, and fill factor tests:

[0121] The current (I)-voltage (V) of the solar cells in each embodiment and comparative example were measured using an IV tester (model: MX-MPVC-A20, manufacturer: Suzhou Maiwei Technology Co., Ltd.) to obtain the open-circuit voltage, short-circuit current density and fill factor of the solar cells.

[0122] Photoelectric conversion efficiency test:

[0123] The current (I)-voltage (V) of the solar cells in each embodiment and comparative example were measured using an IV tester (model: MX-MPVC-A20, manufacturer: Suzhou Maiwei Technology Co., Ltd.) to obtain the photoelectric conversion efficiency (PCE) of the solar cells.

[0124] Table 3 Performance data for each embodiment and comparative example

[0125]

[0126] Referring to Tables 1 and 3, it can be seen from Examples 1 to 5 and Comparative Examples 1 to 2 that when the passivation layer contains only mercaptopyridine compounds (e.g., Comparative Example 1), the fill factor of the solar cell is low, resulting in low photoelectric conversion efficiency. Similarly, when the passivation layer contains only ethylenediamine diiodide (e.g., Comparative Example 2), the fill factor of the solar cell is also low, leading to low photoelectric conversion efficiency. This may be because when the passivation layer contains only mercaptopyridine compounds or only ethylenediamine diiodide, a synergistic effect cannot be achieved, resulting in limited passivation effect of the passivation layer on the perovskite layer. In contrast, the solar cells of Examples 1 to 5 of this application exhibit high photoelectric conversion efficiency. This may be because the mercaptopyridine compounds and ethylenediamine diiodide have a synergistic effect, reducing surface defects in the perovskite layer while reducing interfacial recombination at the top interface between the perovskite layer and the electron transport layer, effectively improving the passivation effect of the passivation layer on the perovskite layer, thereby improving the photoelectric conversion efficiency of the solar cell.

[0127] The type of mercaptopyridine compound usually affects the performance of the passivation layer. As can be seen from Examples 1, 6 to 7, the passivation layer of this application contains both mercaptopyridine compound and ethylenediamine diiodide. By controlling the type of mercaptopyridine compound within the scope of this application, it is beneficial to obtain a passivation layer with excellent passivation effect, thereby improving the photoelectric conversion efficiency of perovskite solar cells.

[0128] As can be seen from Examples 8 to 10, the passivation layer of this application, which contains both mercaptopyridine compounds and ethylenediamine diiodide, also exhibits excellent passivation effect when prepared by sequential deposition, thereby improving the photoelectric conversion efficiency of perovskite solar cells.

[0129] The present application discloses a solar cell, its preparation method, and a photovoltaic module. Specific examples have been used to illustrate the principles and implementation methods of the present 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 the present 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 the present application. Therefore, the content of this specification should not be construed as a limitation of the present application.

Claims

1. A solar cell, characterized in that, It includes a substrate and a hole transport layer, a perovskite layer, a passivation layer and an electron transport layer sequentially disposed on the substrate, wherein the passivation layer is located between the perovskite layer and the electron transport layer; The passivation layer includes mercaptopyridine compounds and ethylenediamine diiodide.

2. The solar cell according to claim 1, characterized in that, The mass percentage of mercaptopyridine compounds in the passivation layer is a, 50% ≤ a ≤ 80%, and the mass percentage of ethylenediamine diiodide in the passivation layer is b, 20% ≤ b ≤ 50%.

3. The solar cell according to claim 2, characterized in that, 60% ≤ a ≤ 70%, 30% ≤ b ≤ 40%.

4. The solar cell according to claim 1, characterized in that, The mercaptopyridine compound is selected from at least one of the following compounds:

5. The solar cell according to claim 1, characterized in that, The structural formula of the ethylenediamine diiodide is:

6. The solar cell according to claim 1, characterized in that, The solar cell includes a perovskite tandem solar cell, and the substrate includes a base cell and a composite layer stacked on the base cell. The hole transport layer, the perovskite layer, the passivation layer and the electron transport layer are stacked sequentially on the composite layer, and the surface of the composite layer facing the hole transport layer has a textured surface.

7. The solar cell according to claim 6, characterized in that, A buffer layer, a first transparent electrode layer, and an anti-reflection layer are also stacked sequentially on the electron transport layer.

8. A method for preparing a solar cell according to any one of claims 1 to 7, characterized in that, Includes the following steps: A substrate is provided, and a hole transport layer and a perovskite layer are sequentially formed on the surface of the composite layer of the substrate; A passivation layer is prepared on the perovskite layer, the passivation layer containing a mercaptopyridine compound and ethylenediamine diiodide; Other functional layers are sequentially prepared on the surface of the passivation layer, and the other functional layers include at least an electron transport layer.

9. The preparation method according to claim 8, characterized in that, The process for preparing the passivation layer includes: A mercaptopyridine compound and ethylenediamine diiodide are dissolved in a first solvent to form a passivation layer precursor solution; The passivation layer precursor liquid is coated on the surface of the perovskite layer, and the passivation layer is formed after annealing.

10. The preparation method according to claim 8, characterized in that, The concentrations of mercaptopyridine compounds in the passivation layer precursor solution were 0.7 mg / mL to 1.3 mg / mL, and the concentrations of ethylenediamine diiodide in the passivation layer precursor solution were 0.3 mg / mL to 0.8 mg / mL.

11. The preparation method according to claim 8, characterized in that, The process for preparing the passivation layer includes: A mercaptopyridine compound is dissolved in a first solvent to form a first solution; Ethylenediamine diiodide is dissolved in a second solvent to form a second solution; The first solution is coated on the surface of the perovskite layer, and after a first annealing treatment, an initial film structure is formed. The second solution is applied to the surface of the initial film structure to fill the areas not completely covered by mercaptopyridine compounds in the initial film structure with ethylenediamine diiodide. After a second annealing treatment, the passivation layer is formed.

12. The preparation method according to claim 11, characterized in that, The concentration of mercaptopyridine compounds in the first solution is 1.4 mg / mL to 1.6 mg / mL, and the concentration of ethylenediamine diiodide in the second solution is 0.6 mg / mL to 0.8 mg / mL.

13. The preparation method according to claim 11, characterized in that, The first solvent includes methanol, and the second solvent includes isopropanol.

14. A photovoltaic module, characterized in that, The photovoltaic module comprises the solar cell according to any one of claims 1 to 7, or the photovoltaic module comprises the solar cell prepared by the preparation method according to any one of claims 8 to 13.

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