Solar cell, preparation method thereof, laminated cell and photovoltaic module

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a solar cell, a preparation method thereof, a laminated cell and a photovoltaic module, and the solar cell comprises a silicon substrate which is provided with a first surface and a second surface which are opposite to each other; the composite structure layer is located on the first surface and comprises an anti-reflection layer and an ultraviolet absorption layer, the ultraviolet absorption layer and the anti-reflection layer are stacked in the first direction, the refractive index of the ultraviolet absorption layer is decreased progressively in the first direction, the refractive index of the anti-reflection layer is decreased progressively in the first direction, and the refractive index of the ultraviolet absorption layer is decreased progressively in the second direction; the refractive index of the ultraviolet absorption layer is larger than that of the antireflection layer, and the first direction is the direction from the second surface to the first surface. The solar cell provided by the embodiment of the invention at least can improve the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

[0001] This application relates to the field of photovoltaics, and particularly to a solar cell, a preparation method of a solar cell, a tandem cell, and a photovoltaic module. Background Art

[0002] As a semiconductor device of clean and renewable energy, a solar cell converts light energy into electrical energy through the photovoltaic effect. When light irradiates the surface of the cell, photons excite electrons in the semiconductor layer of the cell to form an electric current, completing the photovoltaic conversion. However, the current solar cell has insufficient passivation effect under strong ultraviolet irradiation. Summary of the Invention

[0003] Embodiments of this application provide a solar cell, a preparation method of a solar cell, a tandem cell, and a photovoltaic module, which are at least beneficial to improving the photovoltaic conversion efficiency of the solar cell.

[0004] According to some embodiments of this application, a solar cell is provided, including: a silicon substrate having opposite first and second surfaces; a composite structure layer located on the first surface, the composite structure layer including an antireflection layer and an ultraviolet absorption layer, wherein the ultraviolet absorption layer and the antireflection layer are stacked along a first direction, the refractive index of the ultraviolet absorption layer decreases in the first direction, the refractive index of the antireflection layer decreases in the first direction, the refractive index of the ultraviolet absorption layer is greater than the refractive index of the antireflection layer, and the first direction is the direction from the second surface to the first surface.

[0005] In some embodiments, the composite structure layer further includes a field passivation layer, and the field passivation layer is located between the silicon substrate and the ultraviolet absorption layer.

[0006] In some embodiments, the first surface has a first region and a second region alternately arranged along a second direction, and the solar cell further includes a first doped conductive layer and a second doped conductive layer, wherein the first doped conductive layer is located on the second surface and has a first doping type; the second doped conductive layer is located in the first region and has a second doping type, and the first doping type is opposite to the second doping type.

[0007] In some embodiments, the second surface has a third region and a fourth region alternately arranged along the second direction, and the solar cell further includes a first doped conductive layer and a second doped conductive layer, the first doped conductive layer is located in the fourth region and has a first doping type; the second doped conductive layer is located in the third region and has a second doping type, and the first doping type is opposite to the second doping type.

[0008] In some embodiments, the antireflection layer includes a first antireflection layer and a second antireflection layer. Among them, the first antireflection layer is located between the ultraviolet absorption layer and the second antireflection layer. The refractive index of the first antireflection layer is 1.95 to 2.1, and the refractive index of the second antireflection layer is 1.75 to 1.95.

[0009] In some embodiments, the refractive index of the ultraviolet absorption layer ranges from 2.25 to 2.68.

[0010] In some embodiments, the material of the ultraviolet absorption layer includes TiO2. Among them, the atomic ratio of Ti to O is (1:1.7) to (1:2). The ultraviolet absorption layer includes a plurality of absorption sub-layers. In the first direction, the plurality of absorption sub-layers are stacked in sequence, and the atomic ratio of Ti to O in the absorption sub-layer decreases.

[0011] In some embodiments, the decreasing ratio of the atomic ratio of Ti to O in the absorption sub-layer is 7% to 8%.

[0012] In some embodiments, the atomic ratio of Ti in the absorption sub-layer farthest from the silicon substrate to Si in the first antireflection layer of the antireflection layer is (1:6) to (1:5).

[0013] According to some embodiments of the present application, on the other hand, an embodiment of the present application provides a method for manufacturing a solar cell, including: providing a silicon substrate; using a first deposition process to gradually reduce the flow ratio of a titanium precursor source and an oxidant to form an ultraviolet absorption layer on one side of the silicon substrate; using a second deposition process to form an antireflection layer on the ultraviolet absorption layer.

[0014] In some embodiments, the flow ratio of the titanium precursor source and the oxidant is (1:5) to (1:8).

[0015] In some embodiments, the temperature of the second deposition process is 400°C to 500°C.

[0016] In some embodiments, before forming the ultraviolet absorption layer, a field passivation layer is formed on the silicon substrate by an atomic layer deposition process. Among them, the temperature of the atomic layer deposition process is 250°C to 300°C.

[0017] According to some embodiments of the present application, a tandem cell is provided, including: a bottom cell, which is the above-mentioned solar cell or a solar cell prepared by the method for manufacturing the above-mentioned solar cell; a top cell, located on the bottom cell.

[0018] According to some embodiments of the present application, a photovoltaic module is provided, including: a battery string, which is formed by connecting a plurality of the solar cells, or solar cells prepared by a preparation method of a plurality of the solar cells, or a plurality of the tandem cells; an encapsulant film, which is used to cover the surface of the battery string; and a cover plate, which is used to cover the surface of the encapsulant film facing away from the battery string.

[0019] The technical solutions provided by the embodiments of the present application have at least the following advantages:

[0020] The solar cell of the present application includes a composite structure layer. The composite structure layer includes an antireflection layer and an ultraviolet absorption layer, and the ultraviolet absorption layer and the antireflection layer are laminated along a first direction. The refractive index of the antireflection layer decreases in the first direction, that is, the refractive index of the antireflection layer far from the silicon substrate is lower than that of the antireflection layer close to the silicon substrate. When the solar cell forms a photovoltaic module, there will be a packaging structure on the antireflection layer far from the silicon substrate. This packaging structure is usually a glass cover plate. The refractive index of the glass cover plate relative to air is relatively large. The smaller refractive index of the antireflection layer far from the silicon substrate can match the refractive index of the glass cover plate, reduce the reflection and scattering of light at the interface of the antireflection layer, reduce the residence time of light at this interface, and thus inhibit the parasitic absorption at the interface, which can improve the conversion efficiency of the battery. The refractive index of the antireflection layer on the side close to the silicon substrate increases, making the refractive index closer to that of the ultraviolet absorption layer, which can reduce the interface reflection when light exits from the antireflection layer to the ultraviolet absorption layer with a larger refractive index, and improve the light absorption efficiency of the battery. The antireflection layer can be used as a protective layer for the ultraviolet absorption layer, which can reduce the damage caused by the direct irradiation of the ultraviolet absorption layer by ultraviolet rays and maintain its ultraviolet absorption performance. The refractive index of the ultraviolet absorption layer increases from the side close to the antireflection layer to the side close to the silicon substrate. Such a change can, on the one hand, reduce the refractive index difference between the ultraviolet absorption layer and the antireflection layer, reduce the interface reflection, and improve the light absorption efficiency of the battery. On the other hand, the region with a high refractive index has a strong ability to absorb ultraviolet rays, which can reduce the damage of ultraviolet light to the inside of the battery and improve the stability and efficiency of the battery. Through the synergistic effect of the antireflection layer and the ultraviolet absorption layer, the photoelectric conversion efficiency of the solar cell is improved. Description of the Drawings

[0021] One or more embodiments are exemplarily illustrated by the figures in the corresponding drawings. These exemplary illustrations do not limit the embodiments unless otherwise stated. The figures in the drawings do not constitute a proportional limitation; in order to more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the drawings required to be used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0022] Figures 1 to 4 Schematic cross-sectional structure diagram of the TOPCon solar cell provided by the embodiment of the present application;

[0023] Figures 5 to 8 Schematic cross-sectional structure diagram of the back-contact solar cell provided by the embodiment of the present application;

[0024] Figure 9 Schematic flow diagram of a method for manufacturing a solar cell provided by the embodiment of the present application;

[0025] Figure 10 is Figure 9 Schematic cross-sectional structure diagram of the substrate after providing the silicon substrate and before preparing the ultraviolet absorption layer in the method for manufacturing the solar cell in

[0026] Figure 11 is in Figure 10 Schematic cross-sectional structure diagram of the substrate after preparing the ultraviolet absorption layer on the field passivation layer formed in

[0027] Figure 12 is in Figure 11 Schematic cross-sectional structure diagram of the substrate after preparing the antireflection layer on the ultraviolet absorption layer formed in

[0028] Figure 13 Schematic cross-sectional structure diagram of a tandem cell provided by the embodiment of the present application;

[0029] Figure 14 Schematic cross-sectional structure diagram of a photovoltaic module provided by the embodiment of the present application.

[0030] Among them, the above-mentioned drawings include the following reference numerals:

[0031] 10. Silicon substrate; 20. Composite structure layer; 21. Ultraviolet absorption layer; 22. Antireflection layer; 23. Field passivation layer; 24. Oxide layer; 211. First sub-absorption layer; 212. Second sub-absorption layer; 213. Third sub-absorption layer; 221. First antireflection layer; 222. Second antireflection layer; 231. First passivation layer; 232. Second passivation layer; 233. Third passivation layer; 30. First doped conductive layer; 40. Second doped conductive layer; 50. Back passivation layer; 60. First electrode; 70. Second electrode; 80. Bottom cell; 90. Top cell; 100. Solar cell; 101. Encapsulation adhesive film; 102. Cover plate; 103. Conductive strip; A. First region; B. Second region; C. Third region; D. Fourth region;

[0032] 11. Silicon substrate; 200. Composite structure layer; 210. Ultraviolet absorption layer; 220. Antireflection layer; 230. Field passivation layer; 240. Oxide layer; 2110. First sub-absorption layer; 2120. Second sub-absorption layer; 2130. Third sub-absorption layer; 2210. First antireflection layer; 2220. Second antireflection layer; 2310. First passivation layer; 2320. Second passivation layer; 2330. Third passivation layer; 31. First doped conductive layer; 41. Second doped conductive layer; 51. Back passivation layer; 61. First electrode; 71. Second electrode. Detailed implementation manners

[0033] As known from the background art, a solar cell, as a semiconductor device of clean and renewable energy, converts light energy into electrical energy through the photovoltaic effect. When light irradiates the surface of the cell, photons excite electrons in the semiconductor layer of the cell to form an electric current, completing the photoelectric conversion. However, the current solar cells have insufficient passivation effect under strong ultraviolet irradiation.

[0034] The embodiments of the present application provide a solar cell, a preparation method of the solar cell, a stacked cell and a photovoltaic module.

[0035] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality" is more than two, unless otherwise specifically defined.

[0036] Referring to "embodiments" herein means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0037] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: the existence of A, the simultaneous existence of A and B, and the existence of B. In addition, the character " / " in this article generally represents an "or" relationship between the front and rear associated objects.

[0038] In the description of the embodiments of the present application, the term "a plurality" refers to more than two (including two). Similarly, "a plurality of groups" refers to more than two groups (including two groups), and "a plurality of pieces" refers to more than two pieces (including two pieces).

[0039] In the description of the embodiments of the present application, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the embodiments of the present application.

[0040] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "coupling", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0041] In the drawings corresponding to the embodiments of the present application, for better understanding and convenience of description, the thickness and area of the layer are enlarged. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component between the two components. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on a partial edge of the entire surface.

[0042] In the description of the embodiments of the present application, when a certain component "includes" another component, unless otherwise stated, other components are not excluded, and other components may further be included. In addition, when a component such as a layer, film, region, or plate is referred to as "on / located on" another component, it can be "directly on" the other component (i.e., on the surface of the other component and there is no other component between them), or there can be another component between them. In addition, when a layer, film, region, plate, etc. component is "directly located on" another component, or when a layer, film, region, plate, etc. component is located on the surface of another component, it means that there is no other component located between them.

[0043] The terms used in the description of the various embodiments in this document are only used to describe specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "part" is also intended to include the plural form unless the context clearly indicates otherwise. Among them, components include components such as layers, films, regions, or plates.

[0044] The following will elaborate on the various embodiments of the present application in conjunction with the accompanying drawings. However, those of ordinary skill in the art can understand that in the various embodiments of the present application, many technical details are presented to help readers better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0045] According to some embodiments of the present application, a solar cell is provided, as Figures 1 to 4 shown, the TOPCon solar cell includes: a silicon substrate 10 having opposite first and second surfaces; a composite structure layer 20 located on the first surface, the composite structure layer 20 including an ultraviolet absorption layer 21 and an antireflection layer 22. Among them, the ultraviolet absorption layer 21 and the antireflection layer 22 are stacked along a first direction X, the refractive index of the ultraviolet absorption layer 21 decreases in the first direction X, the refractive index of the antireflection layer 22 decreases in the first direction X, and the refractive index of the ultraviolet absorption layer 21 is greater than the refractive index of the antireflection layer 22. The first direction X is the direction from the second surface to the first surface. As Figures 5 to 8 shown, the back contact solar cell includes: a silicon substrate 11 having opposite first and second surfaces; a composite structure layer 200 located on the first surface, the composite structure layer 200 including an ultraviolet absorption layer 210 and an antireflection layer 220. Among them, the ultraviolet absorption layer 210 and the antireflection layer 220 are stacked along a first direction X, the refractive index of the ultraviolet absorption layer 210 decreases in the first direction X, the refractive index of the antireflection layer 220 decreases in the first direction X, and the refractive index of the ultraviolet absorption layer 210 is greater than the refractive index of the antireflection layer 220. The first direction X is the direction from the second surface to the first surface.

[0046] By introducing a composite structure layer into the solar cell, the composite structure layer includes an antireflection layer and an ultraviolet absorption layer, and the ultraviolet absorption layer and the antireflection layer are stacked along the first direction. The refractive index of the antireflection layer decreases in the first direction, that is, the refractive index of the antireflection layer far from the silicon substrate is lower than that of the antireflection layer close to the silicon substrate. Finally, there will be a packaging structure on the antireflection layer far from the silicon substrate, and this packaging structure is usually a glass cover plate. The smaller refractive index of the antireflection layer far from the silicon substrate can match the refractive index of the glass cover plate, reducing the reflection and scattering at the interface of the antireflection layer when light enters the antireflection layer from the glass cover plate, reducing the residence time of light at this interface, thereby suppressing the parasitic absorption at the interface and improving the conversion efficiency of the battery. The refractive index of the antireflection layer on the side close to the silicon substrate increases, making the refractive index of the antireflection layer closer to that of the ultraviolet absorption layer, which can reduce the interface reflection when light exits the antireflection layer to the ultraviolet absorption layer with a larger refractive index and improve the light absorption efficiency of the battery. The antireflection layer can serve as a protective layer for the ultraviolet absorption layer, reducing the damage caused by direct ultraviolet irradiation of the ultraviolet absorption layer and maintaining its ultraviolet absorption performance. The refractive index of the ultraviolet absorption layer increases from the side close to the antireflection layer to the side close to the silicon substrate. Such a change can, on the one hand, reduce the refractive index difference between the ultraviolet absorption layer and the antireflection layer, reduce interface reflection, and improve the light absorption efficiency of the battery. On the other hand, the region with a high refractive index has a strong ability to absorb ultraviolet light, reducing the damage of ultraviolet light to the inside of the battery and improving the stability and efficiency of the battery. Through the synergistic effect of the antireflection layer and the ultraviolet absorption layer, the photoelectric conversion efficiency of the solar cell is improved.

[0047] In the above embodiment, the material of the silicon substrate can be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, for example, it can be silicon. Among them, the elemental semiconductor material can be in single crystal state, polycrystalline state, amorphous state or microcrystalline state (the state with both single crystal state and amorphous state is called microcrystalline state). For example, silicon can be at least one of single crystal silicon, polycrystalline silicon, amorphous silicon or microcrystalline silicon.

[0048] In the above embodiment, the material of the silicon substrate can also be a compound semiconductor material. Common compound semiconductor materials include but are not limited to materials such as silicon germanide, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, copper indium selenide, etc. The silicon substrate can also be a sapphire silicon substrate, a silicon-on-insulator substrate or a germanium silicon-on-insulator substrate.

[0049] In the above embodiments, the N-type silicon substrate is doped with an N-type doping element, and the N-type doping element can be at least one of Group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type silicon substrate is doped with a P-type element, and the P-type doping element can be at least one of Group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In). Optionally, the thickness of the N-type silicon substrate can be 100 μm to 210 μm, such as 130 μm, 170 μm, and 190 μm, etc.

[0050] In the above embodiments, the first surface of the silicon substrate is the front surface, and the second surface is the back surface, that is, the solar cell is a single-sided cell. The front surface can be used as the light-receiving surface for receiving incident light, and the back surface is used as the backlight surface.

[0051] The above first surface and second surface can be a flat surface or a non-flat surface respectively, that is, the first surface can be a flat surface or a non-flat surface, the second surface can be a flat surface or a non-flat surface, and the first surface and the second surface can be the same or different.

[0052] In the above embodiments, both the above first surface and second surface are non-flat surfaces. The non-flat surface can increase the internal reflection of incident light, thereby further improving the light utilization rate of the solar cell. More specifically, the cross-section of the non-flat surface along the first predetermined direction is a line segment, and the line segment can include at least one of a straight line segment and a curved line segment, that is, the line segment can be composed of straight line segments, can be composed of curved line segments, or can be composed of curved line segments and straight line segments. In the case of being only composed of straight line segments, the line segment is composed of a plurality of sequentially connected straight line segments. Among them, the first predetermined direction is the thickness direction of the silicon substrate.

[0053] The composite passivation layer of the present application can be used in TOPCon cells. In some embodiments, as Figures 1 to 4 shown, the solar cell can be a TOPCon cell. The first surface has a first region A and a second region B alternately arranged along the second direction Y. The solar cell further includes a first doped conductive layer 30 and a second doped conductive layer 40. Among them, the first doped conductive layer 30 is located on the second surface and has a first doping type; the second doped conductive layer 40 is located in the first region A and has a second doping type, and the first doping type is opposite to the second doping type.

[0054] In the above embodiments, the above first region refers to the region where an electrode is formed in the cell, and is also called the metal region. The second region is the region in the cell other than the first region, and is also called the non-metal region.

[0055] The composite passivation layer of the present application can be used in back-contact cells. In some embodiments, as Figures 5 to 8As shown, the solar cell can be a back-contact cell. The second surface has a third region C and a fourth region D alternately arranged along the second direction Y. The solar cell further includes a first doped conductive layer 31 and a second doped conductive layer 41. The first doped conductive layer 31 is located in the fourth region D and has a first doping type; the second doped conductive layer 41 is located in the third region C and has a second doping type, and the first doping type is opposite to the second doping type. The composite passivation layer of the present application can be applied to TOPCon cells, back-contact cells, and their stacked cells, with a wide range of applications.

[0056] In the above embodiments, the first doped conductive layer and the second doped conductive layer can be doped polysilicon layers, or can be silicon carbide layers, or can be a composite layer of a doped polysilicon layer and a silicon carbide layer. For example, it can be only silicon carbide or only polysilicon, or can be a doped material of silicon carbide and polysilicon; when the first doped conductive layer is doped polysilicon (Doped poly-Si), it can be used as a field passivation layer to form a band bending on the silicon wafer surface to achieve selective transport of carriers and reduce recombination losses. The thickness of the above first doped conductive layer and second doped conductive layer can be 80 nm to 100 nm, such as 80 nm and 95 nm, etc. The specific thickness and material are not limited in the present application and can be selected according to actual situations.

[0057] In the above embodiments, as Figures 1 to 4 shown, when the above solar cell is a TOPCon cell, the cell further has a back surface passivation layer 50; as Figures 5 to 8 shown, when the above solar cell is a back-contact cell, the cell further has a back surface passivation layer 51. Among them, the back surface passivation layer can inhibit carrier recombination at the interface, thus avoiding the problem of reduced photocurrent caused by carrier recombination, and ensuring a relatively high photoelectric conversion efficiency of the cell. Optionally, the material of the above back surface passivation layer can be a single-layer film layer or a composite film layer such as alumina, silicon nitride, silicon oxide, and silicon oxynitride. For example, when the back surface passivation layer is a single-layer film layer, the back surface passivation layer can be an alumina single-layer film layer, a silicon nitride single-layer film layer, a silicon oxide single-layer film layer, or a silicon oxynitride single-layer film layer; when the back surface passivation layer is a multi-layer film layer, the back surface passivation layer can be a composite film layer of alumina and silicon oxide, or a composite film layer of alumina, silicon oxide, and silicon nitride. Of course, the material of the back surface passivation layer of the present application is not limited to the above materials, and those skilled in the art can select any suitable material to form the back surface passivation layer of the present application according to actual situations. Optionally, the thickness of the back surface passivation layer of the present application can be 70 nm to 90 nm, which can further ensure a reduction in the density of defect states on the surface of the cell wafer, reduce the probability of surface recombination of electrons and holes, and thus improve the photoelectric conversion efficiency.

[0058] In the above embodiments, asFigures 1 to 4 As shown, when the above solar cell is a TOPCon cell, the cell further includes a first electrode 60 and a second electrode 70. The first electrode 60 is located on the side of the first doped conductive layer 30 away from the silicon substrate 10, and the second electrode 70 is located on the side of the second doped conductive layer 40 away from the silicon substrate 10; as Figures 5 to 8 As shown, when the above solar cell is a back-contact cell, the cell further includes a first electrode 61 and a second electrode 71. The first electrode 61 is located on the side of the first doped conductive layer 31 away from the silicon substrate 11, and the second electrode 71 is located on the side of the second doped conductive layer 41 away from the silicon substrate 11. Among them, the materials of the first electrode and the second electrode can independently be selected from copper, silver, nickel or aluminum; this application does not limit the materials and thicknesses of the first electrode and the second electrode, and those skilled in the art can select appropriate materials and thicknesses to form the first electrode and the second electrode according to actual situations.

[0059] In some embodiments, as Figures 2 to 4 As shown, when the above solar cell is a TOPCon cell, the antireflection layer 22 includes a first antireflection layer 221 and a second antireflection layer 222. Among them, the first antireflection layer 221 is located between the ultraviolet absorption layer 21 and the second antireflection layer 222; as Figures 6 to 8As shown, when the above solar cell is a back contact cell, the antireflection layer 220 includes a first antireflection layer 2210 and a second antireflection layer 2220. Among them, the first antireflection layer 2210 is located between the ultraviolet absorption layer 210 and the second antireflection layer 2220. Specifically, in the direction from the second surface to the first surface, the refractive index change range of the first antireflection layer is 1.95 - 2.1, and the refractive index change range of the second antireflection layer is 1.75 - 1.95. The material of the first antireflection layer can be SiNx, the thickness can be 50 nm, and the atomic ratio of Si to N can be (1:1.2) - (1:1.4); the material of the second antireflection layer can be SiOx, the thickness can be 30 nm, and the atomic ratio of Si to N can be (1:1.7) - (1:1.9). The refractive index of the above second antireflection layer is close to that of the glass cover plate (n = 1.5) of the solar cell, and it can be used as a transition layer for light to enter the cell from the glass cover plate, reducing the reflection and scattering of light at the interface of the second antireflection layer, reducing the residence time of light, and suppressing the parasitic absorption at the interface. The refractive index of the above first antireflection layer is greater than that of the second antireflection layer and less than that of the ultraviolet absorption layer, and it can be used as a transition layer for light to enter the ultraviolet absorption layer 21 from the second antireflection layer, reducing the reflection and scattering of light at the interface of the ultraviolet absorption layer, suppressing the interface absorption. Most of the light can be smoothly conducted to the ultraviolet absorption layer through the antireflection layer, entering the interior of the cell, reducing the waste of light, and enabling the cell to absorb more light. Moreover, with the antireflection layer of the above double-layer structure, the weighted average reflectivity of the cell is 2.1% (for light in the 300 - 1200 nm band), which is lower than the weighted average reflectivity (4.5%) of the single-layer structure antireflection layer, reducing light reflection, retaining more light for the cell, and increasing the photocurrent gain of the cell by about 0.8 mA / cm².

[0060] In the visible and near-infrared spectral ranges, the outermost material of the antireflection layer being SiOx has a lower light absorption coefficient compared to the outermost material of the antireflection layer being SiNx, that is, the SiOx layer can transmit more light and absorb less light energy itself, which can reduce the light loss between the encapsulation material and the cell surface.

[0061] In some embodiments, as Figures 1 to 4 shown, when the above solar cell is a TOPCon cell, the composite structure layer 20 further includes a field passivation layer 23, and the field passivation layer 23 is located between the silicon substrate 10 and the ultraviolet absorption layer 21. As Figures 5 to 8As shown, in the case where the above-mentioned solar cell is a back-contact cell, the composite structure layer 200 further includes a field passivation layer 230, and the field passivation layer 230 is located between the silicon substrate 11 and the ultraviolet absorption layer 210. Among them, the thickness of the field passivation layer can be 6 nm to 10 nm, which can inhibit the carrier recombination at the interface, thus avoiding the problem of the reduction of the photocurrent caused by the carrier recombination, and ensuring a relatively high photoelectric conversion efficiency of the battery. As Figures 1 to 4 shown, the composite structure layer 20 of the TOPCon cell further includes an oxide layer 24, and the oxide layer 24 is located between the silicon substrate 10 and the field passivation layer 23; as Figures 5 to 8 shown, the composite structure layer 200 of the back-contact cell further includes an oxide layer 240, and the oxide layer 240 is located between the silicon substrate 11 and the field passivation layer 230. Among them, the oxide layer material can be at least one of silicon oxide, silicon oxynitride, titanium oxide and silicon nitride, and the thickness can be 1 to 5 nm. The oxide layer 24 can passivate the dangling bonds on the surface of the silicon substrate, reduce the surface recombination centers, and improve the performance of the battery.

[0062] In the above embodiment, the atomic ratio of Ti in the ultraviolet absorption layer to Al in the field passivation layer can be (2:5) to (9:20). The material of the field passivation layer can include Al2O3, and the material of the ultraviolet absorption layer can include TiO2. Among them, the atomic ratio of Ti to Al can be selected as 3:7, so that a Ti-O-Al bond can be better formed at the contact interface between the field passivation layer and the ultraviolet absorption layer. The bond energy of the Ti-O-Al bond is about 6.2 eV, which is greater than the bond energy of the Ti-O-Ti bond (5.8 eV) in the TiO2 layer, and the structure is more stable, which can inhibit the interface defects. The thermal expansion coefficient from the field passivation layer to the ultraviolet absorption increases in a gradient: the thermal expansion coefficient of the Al2O3 layer is: 8×10 -6 / K, and the thermal expansion coefficient of the Ti3AlOx layer generated at the interface between the field passivation layer and the ultraviolet absorption layer is 8.2×10 -6 / K, and the thermal expansion coefficient of the TiO2 layer is 9×10 -6 / K, so that the thermal stress of the battery can be reduced (about 40%).

[0063] In some embodiments, as Figures 3 to 4 shown, in the case where the above-mentioned solar cell is a TOPCon cell, the field passivation layer 23 includes a first passivation layer 231, a second passivation layer 232 and a third passivation layer 233; as Figures 7 to 8As shown, when the above-mentioned solar cell is a back-contact cell, the field passivation layer 230 includes a first passivation layer 2310, a second passivation layer 2320, and a third passivation layer 2330. Among them, in the first direction X, the first passivation layer, the second passivation layer, and the third passivation layer are stacked in sequence. Among them, the material of the first passivation layer can be SiO2, the thickness can be 1 to 2 nm, and the atomic ratio of Si and O can be 1:2; the material of the second passivation layer can be Al2O3, the thickness can be 3 to 5 nm, and the atomic ratio of Al and O can be 2:3; the material of the third passivation layer can be SiON, the thickness can be 2 to 3 nm, and the atomic ratio of Si, O, and N can be 1:0.6:0.4. Setting the material, thickness, and atomic ratio of the third passivation layer within the above ranges can make the film layer structure have better densification, and the diffusion coefficient is less than 10 -16 cm 2 / s, which can prevent the gas H2 introduced during the film layer preparation from excessively penetrating into the second passivation layer and maintain the structural stability of the field passivation layer. Setting the material, thickness, and atomic ratio of the second passivation layer within the above ranges can control the charge density of the film layer at -3×10 12 cm -2 , inhibit electron recombination, and improve the field passivation effect of negative charges. Setting the material, thickness, and atomic ratio of the first passivation layer within the above ranges can reduce the lattice mismatch rate between the SiO2 film layer and the Al2O3 film layer to 1.2% and reduce the interface state density.

[0064] In some embodiments, the refractive index of the ultraviolet absorption layer ranges from 2.25 to 2.68. Setting the refractive index of the ultraviolet absorption layer within the above ranges can better reduce the refractive index difference between the ultraviolet absorption layer and the antireflection layer, reduce interface reflection, improve the light absorption efficiency of the battery, and the region with a high refractive index has a strong ultraviolet absorption ability, reducing the damage of ultraviolet light to the inside of the battery and improving the stability and efficiency of the battery.

[0065] In some embodiments, the material of the ultraviolet absorption layer includes TiO2, where the atomic ratio of Ti to O is (1:1.7) to (1:2), as Figure 4 shown, the ultraviolet absorption layer 21 of the TOPCon cell includes multiple absorption sub-layers. In the first direction X, the multiple absorption sub-layers are stacked in sequence, and the atomic ratio of Ti to O in the absorption sub-layers decreases. Among them, in the first direction X, the multiple absorption sub-layers may include a first sub-absorption layer 211, a second sub-absorption layer 212, and a third sub-absorption layer 213 stacked in sequence; as Figure 8As shown, the ultraviolet absorption layer 210 of the back-contact battery includes multiple absorption sub-layers. In the first direction X, the multiple absorption sub-layers are stacked in sequence, and the atomic ratio of Ti to O in the absorption sub-layers decreases. Among them, in the first direction X, the multi-layer absorption sub-layers may include a first sub-absorption layer 2110, a second sub-absorption layer 2120, and a third sub-absorption layer 2130 that are stacked in sequence. Among them, the thickness of the first sub-absorption layer may be 3 nm, the refractive index may be 2.52 - 2.68, and the atomic ratio of Ti to O may be (1:1.7) - (1:1.9); the thickness of the second sub-absorption layer may be 5 nm, the refractive index may be 2.38 - 2.52, and the atomic ratio of Ti to O may be (1:1.9) - (1:1.95); the thickness of the third sub-absorption layer may be 4 nm, the refractive index may be 2.25 - 2.38, and the atomic ratio of Ti to O may be (1:1.95) - (1:2). Setting the thickness, refractive index, and atomic ratio of Ti to O of the above-mentioned third sub-absorption layer within the above ranges can reduce light reflection at the interface of the third sub-absorption layer, making the film layer have less than 10 17 cm -3 low oxygen vacancies and reduce the recombination of photo-generated carriers; setting the thickness, refractive index, and atomic ratio of Ti to O of the above-mentioned third sub-absorption layer within the above ranges can make the carrier mobility of the film layer about 15 cm 2 / V•s, balancing absorption and carrier transport; setting the thickness, refractive index, and atomic ratio of Ti to O of the above-mentioned first sub-absorption layer within the above ranges can make the film layer in a Ti-rich 3+ state, with an oxygen vacancy concentration of about 5×10 19 cm -3 , enhancing the absorption efficiency of ultraviolet rays.

[0066] In the above embodiment, the overall thickness of the ultraviolet absorption layer may be 9 nm - 15 nm. Setting the thickness of the ultraviolet absorption layer within the above range can absorb more ultraviolet rays under the condition of a moderate battery size, reduce the damage of ultraviolet light to the inside of the battery, and further improve the photoelectric conversion efficiency of the solar cell.

[0067] In some embodiments, the decreasing ratio of the atomic ratio of Ti to O in the absorption sub-layers is 7% - 8%. Setting the decreasing ratio of the atomic ratio of Ti to O in the absorption sub-layers within the above range can improve the energy band gradient (the conduction band offset is 0.2 eV), drive the directional migration of photo-generated electrons, and improve the photoelectric conversion efficiency of the battery.

[0068] In some embodiments, the absorber sub-layer farthest from the silicon substrate is the third sub-absorber layer, and the atomic ratio of Ti in the third sub-absorber layer to Si in the first anti-reflection layer of the anti-reflection layer is (1:6) to (1:5). Optionally, Ti:Si is 1:4, and an Si-O-Ti bond (infrared peak position 920 cm-1) can be generated at the interface between the ultraviolet absorption layer and the first anti-reflection layer, which can gradually change the refractive index from the refractive index of the ultraviolet absorption layer to the refractive index of the first anti-reflection layer, reducing the interface reflection. In this way, the interface recombination rate at this interface is about 10 cm / s, which is significantly lower than that of a traditional mechanical interface (above 100 cm / s).

[0069] The technical solution of the present application can be used in full-back electrode contact cells of the non-main grid technology (0BB, Zero Busbar) or multi-main grid technology (MBB, MULTI-BUSBAR), full-back electrode contact cells (IBC, Interdigitated BackContact), full-back contact solar cells (ABC, All Back Contact), compound passivated back contact cells (HPBC, Hybrid Passivated Back Contact), passivated emitter and rear cells (PERC, PassivatedEmitter and Rear Cell), tunneling oxide passivated contact cells (TOPCon, Tnuuel Oxide Passivatedcontact), TOPCon-IBC (Interdigitated Back Contact, IBC) cells, crystalline silicon heterojunction solar cells (HJT, Heterojunction with Intrinsic Thin-layer), perovskite tandem cells, flexible cells and other photovoltaic cells.

[0070] According to some embodiments of the present application, a method for preparing a solar cell is provided, as Figure 9 shown, including:

[0071] Step S1: As Figure 10 shown, provide a silicon substrate 11;

[0072] Specifically, the material of the silicon substrate can be an elemental semiconductor material, a compound semiconductor material or a sapphire substrate. Specifically, the elemental semiconductor material is composed of a single element, for example, it can be silicon. Among them, the elemental semiconductor material can be in single crystal state, polycrystalline state, amorphous state or microcrystalline state (a state with both single crystal state and amorphous state is called microcrystalline state). For example, silicon can be at least one of single crystal silicon, polycrystalline silicon, amorphous silicon or microcrystalline silicon. The compound semiconductor materials include but are not limited to materials such as silicon germanide, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, copper indium selenide, etc.

[0073] Step S2: As shown in Figure 10 and Figure 11 , using the first deposition process, control the flow ratio of the titanium precursor source and the oxidant to gradually decrease, and form an ultraviolet absorption layer 210 on one side of the silicon substrate;

[0074] Specifically, as shown in Figure 10 , before preparing the ultraviolet absorption layer, an oxide layer 240 and a field passivation layer 230 are first prepared on one side of the silicon substrate 11. In some embodiments, the field passivation layer is formed on the silicon substrate by atomic layer deposition (ALD). Among them, the temperature of the atomic layer deposition process is 250°C to 300°C. Among them, the temperature can be 250°C, 280°C, and 300°C. More specifically, the material of the oxide layer 240 is deposited on the silicon substrate 11 by the ALD process, and a chemical reaction occurs to generate the oxide layer. The material of the oxide layer 240 can be SiO2. The specific reaction principle can be: in an environment of 250°C, silane (SiH4) reacts with O2 to generate SiO2. The thickness of the oxide layer 240 can be 1 nm to 5 nm, which can passivate the dangling bonds on the surface of the silicon substrate 11, reduce the surface recombination center, and improve the performance of the battery. The material of the field passivation layer 230 is deposited on the oxide layer 240 by the ALD process, and a chemical reaction occurs to generate the field passivation layer 230. The field passivation layer 230 can be a single-layer film or a multi-layer module. When the field passivation layer 230 is a single-layer film, the material can be Al2O3. The specific reaction principle can be: in an environment of 300°C, trimethylaluminum (TMA) reacts with H2O to generate Al2O3. The thickness of the field passivation layer 230 can be 6 nm to 10 nm; Figure 10 The field passivation layer 230 shown in

[0075] is a multi-layer film, including a first passivation layer 2310, a second passivation layer 2320, and a third passivation layer 2330. The materials can be SiO2, Al2O3, and SiON respectively, and the thicknesses can be 1 nm to 2 nm, 3 nm to 5 nm, and 2 nm to 3 nm respectively. The above-mentioned field passivation layer 230 can suppress the carrier recombination at the interface, thus avoiding the problem of the reduction of the photocurrent caused by the carrier recombination, and ensuring a relatively high photoelectric conversion efficiency of the battery.

[0075] Specifically, as shown in Figure 11As shown, the ultraviolet absorption layer 210 can be prepared on the field passivation layer 230 by using the PECVD process. When using TiCl4 and O2 as precursors, with a reaction temperature of 400 °C and a gas pressure of 200 Pa, the flow rate ratio of TiCl4 and O2 can be controlled to achieve a gradual change in the atomic ratio of Ti and O and a gradual change in the refractive index in the ultraviolet absorption layer 210. The ultraviolet absorption layer 210 includes a first sub-absorption layer 2110, a second sub-absorption layer 2120, and a third sub-absorption layer 2130, where the first sub-absorption layer 2110, the second sub-absorption layer 2120, and the third sub-absorption layer 2130 are stacked in sequence in the first direction X.

[0076] Step S3: As Figure 12 shown, an anti-reflection layer 220 is formed on the ultraviolet absorption layer 210 by using a second deposition process.

[0077] Specifically, as Figure 12 shown, the anti-reflection layer 220 can be prepared on the ultraviolet absorption layer by using the PECVD process. The anti-reflection layer 220 can include a first anti-reflection layer 2210 and a second anti-reflection layer 2220. In some embodiments, the temperature of the second deposition process is 400 °C to 500 °C. Among them, the temperature can be 450 °C, 480 °C, etc. More specifically, to prepare the first anti-reflection layer 2210 on the ultraviolet absorption layer 210, a SiH4 / NH3 / H2 mixed gas (the ratio can be 1:4:2) can be introduced at a deposition temperature of 450 °C. To prepare the second anti-reflection layer 2220 on the first anti-reflection layer 2210, a SiH4 / NO2 / H2 mixed gas (the ratio can be 1:8:2) can be introduced at a deposition temperature of 450 °C. After preparing these two layers of structures, the film layer is then annealed in a nitrogen atmosphere at a temperature of 400 °C for 30 minutes to promote the migration of hydrogen atoms to the interface. Thus, the composite structure layer 200 is formed.

[0078] Figures 10 to 12 The figure schematically shows the preparation structure diagram of the composite structure layer in the back-contact battery. The preparation of the composite structure layer in the TOPCon battery is the same as that in the back-contact battery, and this application will not repeat the description.

[0079] In some embodiments, the flow rate ratio of the titanium precursor source and the oxidant is (1:5) to (1:8). The titanium precursor can be TiCl4, and the oxidant can be O2. During the preparation of the ultraviolet absorption layer, the flow rate ratio is gradually controlled to increase. In this way, an ultraviolet absorption layer with an increasing atomic ratio of Ti and O and a decreasing refractive index can be prepared. The refractive index difference between the formed ultraviolet absorption layer and the anti-reflection layer with a smaller refractive index will be reduced, reducing the interface reflection of light. Moreover, the region with a high refractive index has a strong ultraviolet absorption ability, reducing the damage of ultraviolet light to the inside of the battery and improving the stability and efficiency of the battery.

[0080] According to an embodiment of the present application, a tandem cell is further provided, as Figure 13 shown, including: a bottom cell 80, which is the above-mentioned solar cell or a solar cell prepared by the above-mentioned method for preparing a solar cell; a top cell 90, located on the bottom cell.

[0081] In some embodiments, the first transport layer can be either an electron transport layer or a hole transport layer, and the second transport layer can be the other of the electron transport layer or the hole transport layer. For example, the first transport layer is an electron transport layer and the second transport layer is a hole transport layer, or the first transport layer is a hole transport layer and the second transport layer is an electron transport layer.

[0082] According to an embodiment of the present application, a photovoltaic module is further provided, as Figure 14 shown, including: a battery string, which is formed by connecting a plurality of the above-mentioned solar cells 100, or a solar cell 100 prepared by the above-mentioned method for preparing a solar cell, or a plurality of the above-mentioned tandem cells; an encapsulation film 101, used to cover the surface of the battery string; a cover plate 102, used to cover the surface of the encapsulation film 101 facing away from the battery string. The solar cells 100 can be electrically connected through a conductive strip 103, and the conductive strip 103 is welded to the electrode on the solar cell 100.

[0083] The above-mentioned encapsulation film can be an organic encapsulation film such as a polyvinyl butyral (PVB) film, an ethylene-vinyl acetate copolymer (EVA) film, a polyethylene octene copolymer (POE) film, or a polyethylene terephthalate (PET) film. Or, at least one of the first encapsulation layer or the second encapsulation layer can also be an EP film, an EPE film, or a PVP film. Among them, the EP film refers to a co-extruded film composed of an EVA film and a POE film stacked, the EPE film refers to a co-extruded film formed by sequentially stacking an EVA film + a POE film + an EVA film, and the PVP film refers to a co-extruded film formed by stacking a POE film + an EVA film + a POE film. The co-extruded film can be manufactured by extruding one or more raw materials onto another film that has been made in the process of film processing, or by bonding different types of films that have been made together.

[0084] The above-mentioned cover plate can be a cover plate with a light-transmitting function such as a glass cover plate or a plastic cover plate. Specifically, the surface of the cover plate facing the encapsulation film can be a concave-convex surface or a suede surface including a plurality of convex structures, which can increase the utilization rate of incident light.

[0085] Next, the above-mentioned method for preparing a solar cell of the present application will be specifically described in combination with specific embodiments and comparative examples.

[0086] Example 1

[0087] This application provides a method for preparing a solar cell, including:

[0088] Providing a silicon substrate having opposite first and second surfaces, the silicon substrate being a silicon wafer with a thickness of 150 μm;

[0089] Preparing an oxide layer on the first surface by ALD process, with a reaction temperature of 250 °C, the material of the oxide layer being SiO2 and the thickness being 1 nm;

[0090] Preparing a field passivation layer on the oxide layer by ALD process, the field passivation layer including a first sub-passivation layer, a second sub-passivation layer and a third sub-passivation layer. The materials of the first sub-passivation layer, the second sub-passivation layer and the third sub-passivation layer are SiO2, Al2O3 and SiON respectively, and the thicknesses are 1 nm, 3 nm and 2 nm respectively, with a reaction temperature of 300 °C.

[0091] Preparing an ultraviolet absorption layer on the field passivation layer by PECVD process, the ultraviolet absorption layer including a first sub-absorption layer, a second sub-absorption layer and a third sub-absorption layer. Among them, the flow rate ratio of TiCl4 to O2 when preparing the first sub-absorption layer is 1:5, the ratio of Ti to O atoms in the first sub-absorption layer is 1:1.8, and the refractive index is 2.68; the flow rate ratio of TiCl4 to O2 when preparing the second sub-absorption layer is 1:6, the ratio of Ti to O atoms in the second sub-absorption layer is 1:1.9, and the refractive index is 2.52; the flow rate ratio of TiCl4 to O2 when preparing the third sub-absorption layer is 1:8, the ratio of Ti to O atoms in the third sub-absorption layer is 1:95, and the refractive index is 2.45; the reaction temperature is 400 °C, the air pressure is 200 Pa, the material of the ultraviolet absorption layer is TiO2, and the thickness of the ultraviolet absorption layer is 12 nm.

[0092] Preparing an antireflection layer on the ultraviolet absorption layer by PECVD process, the antireflection layer including a first antireflection layer and a second antireflection layer. The material of the first antireflection layer is Si3N4, the thickness is 50 nm, and in the direction from the second surface to the first surface, the refractive index changes from 1.95 to 2; the material of the second antireflection layer is SiO2, in the direction from the second surface to the first surface, the refractive index changes from 1.75 to 1.85, the thickness is 30 nm, and the deposition temperature is 450 °C.

[0093] Forming a first doped conductive layer on the second surface, with a doping type of N-type and a thickness of 80 nm;

[0094] Forming a second doped conductive layer on the first region of the first surface, with a doping type of P-type and a thickness of 80 nm;

[0095] A first electrode and a second electrode are respectively formed on one side of the first doped conductive layer and the second doped conductive layer facing away from the silicon substrate. The materials of the first electrode and the second electrode are Ag, and the thickness of both is 10 μm.

[0096] Example 2

[0097] This application provides a method for manufacturing a solar cell, including:

[0098] The difference from Example 1 is that in the direction from the second surface to the first surface, the refractive index change of the first antireflection layer is 1.95 - 2.1, and the refractive index change of the second antireflection layer is 1.75 - 1.95.

[0099] Example 3

[0100] This application provides a method for manufacturing a solar cell, including:

[0101] The difference from Example 1 is that in the direction from the second surface to the first surface, the refractive index change of the first antireflection layer is 1.95 - 2.3, and the refractive index change of the second antireflection layer is 1.75 - 2.05.

[0102] Example 4

[0103] This application provides a method for manufacturing a solar cell, including:

[0104] The difference from Example 1 is that the atomic ratio of Ti in the third sub - absorption layer to Si in the first antireflection layer is 1:4.

[0105] Example 5

[0106] This application provides a method for manufacturing a solar cell, including:

[0107] The difference from Example 4 is that the atomic ratio of Ti in the third sub - absorption layer to Si in the first antireflection layer is 1:5.

[0108] Example 6

[0109] This application provides a method for manufacturing a solar cell, including:

[0110] The difference from Example 4 is that the atomic ratio of Ti in the third sub - absorption layer to Si in the first antireflection layer is 1:6.

[0111] Example 7

[0112] This application provides a method for manufacturing a solar cell, including:

[0113] The difference from Example 4 is that the atomic ratio of Ti in the third sub - absorption layer to Si in the first antireflection layer is 1:7.

[0114] Example 8

[0115] The present application provides a method for preparing a solar cell, including:

[0116] It is different from Example 4 in that the atomic ratio of Ti in the third sub-absorbing layer to Si in the first anti-reflection layer is 1:8.

[0117] Example 9

[0118] The present application provides a method for preparing a solar cell, including:

[0119] It is different from Example 1 in that the refractive index of the first sub-absorbing layer is 2.52, and the atomic ratio of Ti to O is 1:1.9; the refractive index of the third sub-absorbing layer is 2.38, and the atomic ratio of Ti to O is 1:1.95.

[0120] Example 10

[0121] The present application provides a method for preparing a solar cell, including:

[0122] It is different from Example 1 in that the refractive index of the first sub-absorbing layer is 2.88, and the atomic ratio of Ti to O is 1:1.7; the refractive index of the third sub-absorbing layer is 2.25, and the atomic ratio of Ti to O is 1:2.

[0123] Comparative Example 1

[0124] A method for preparing a solar cell, including:

[0125] It is different from Example 1 in that the refractive index of the ultraviolet absorption layer is fixed at 2.5.

[0126] Comparative Example 2

[0127] A method for preparing a solar cell, including:

[0128] It is different from Example 1 in that there is no ultraviolet absorption layer.

[0129] Comparative Example 3

[0130] A method for preparing a solar cell, including:

[0131] It is different from Comparative Example 2 in that the anti-reflection layer is a single-layer structure, the material is Si3N4, and the refractive index is fixed at 1.95.

[0132] Comparative Example 4

[0133] A method for preparing a solar cell, including:

[0134] The difference from Example 1 is that the antireflection layer is a single-layer structure, the material is Si3N4, and the refractive index is fixed at 1.95.

[0135] The performance of the solar cells prepared by the preparation methods of the above Examples 1 to 10 and Comparative Examples 1 to 4 was tested. Taking the TOPCon cell as an example of the type of solar cell, the test results are shown in Table 1:

[0136] Table 1

[0137] Absorbance (L / (g·cm)) Light reflectance % Conversion efficiency % Example 1 1.25 2.1 25.7 Example 2 1.2 2.2 25.5 Example 3 1.21 2.3 25.4 Example 4 1.25 2.1 25.6 Example 5 1.23 2.2 25.4 Example 6 1.24 2.3 25.5 Example 7 1.22 2.4 25.2 Example 8 1.23 2.5 25.1 Example 9 1.245 2.35 25.15 Example 10 1.28 2.2 25.6 Comparative Example 1 1.24 2.5 25.0 Comparative Example 2 0.95 2.3 25.2 Comparative Example 3 0.1 4.0 24.5 Comparative Example 4 1.2 4.5 24.8

[0138] Among them, the absorbance represents the ability to absorb ultraviolet light; the light reflectance represents the degree of reflecting the incident light. The larger the light reflectance, the more the incident light is reflected, and the less light can be utilized by the battery; the conversion efficiency represents the working efficiency of the battery.

[0139] It can be seen from Table 1 above that Example 12 adjusted the refractive index and atomic ratio of the first sub-absorbing layer relative to Example 1, further improving the absorbance. Compared with Comparative Example 2, the ultraviolet light absorption ability of the battery in Example 1 was greatly improved. Compared with Comparative Example 3, the light reflectance in Example 1 was significantly reduced, allowing more light to enter the battery interior. Compared with Example 3, the light reflectance of the battery in Examples 1 to 2 was reduced due to the refractive index range settings of the first and second antireflection layers of the battery, allowing more light to enter the battery and be converted by the battery. Examples 4 to 6 adjusted the atomic ratio of Ti to Si between the third sub-absorbing layer and the first antireflection layer relative to Examples 7 to 8, which can reduce the recombination rate at the interface between the third sub-absorbing layer and the first antireflection layer and thus improve the photoelectric conversion efficiency of the battery. By adjusting the refractive index change range (the range from the first sub-absorbing layer transition to the second and third sub-absorbing layers) in the ultraviolet absorption layer in Examples 1, 9, and 10, it can be seen that the comprehensive effect of absorbance and light reflectance is better than that of Comparative Example 1. From this analysis, it can be known that the solar cells of the present application have improved in terms of absorbance, light reflection degree, and photoelectric conversion efficiency.

[0140] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present application. In actual applications, various changes can be made in form and details without departing from the spirit and scope of the present application. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the protection scope of the present application should be determined by the scope defined by the claims.

Claims

1. A solar cell, characterized in that, Comprising: A silicon substrate having opposite first and second surfaces; A composite structure layer located on the first surface, the composite structure layer including an antireflection layer and an ultraviolet absorption layer, wherein the ultraviolet absorption layer and the antireflection layer are stacked along a first direction, the refractive index of the ultraviolet absorption layer decreases in the first direction, the refractive index of the antireflection layer decreases in the first direction, the refractive index of the ultraviolet absorption layer is greater than the refractive index of the antireflection layer, and the first direction is the direction from the second surface to the first surface.

2. The solar cell according to claim 1, wherein The composite structure layer further includes a field passivation layer located between the silicon substrate and the ultraviolet absorption layer.

3. The solar cell according to claim 1, characterized in that, The first surface has a first region and a second region alternately arranged along a second direction, and the solar cell further includes a first doped conductive layer and a second doped conductive layer, wherein the first doped conductive layer is located on the second surface and has a first doping type; the second doped conductive layer is located in the first region and has a second doping type, and the first doping type is opposite to the second doping type.

4. The solar cell according to claim 3, characterized in that, The second surface has a third region and a fourth region alternately arranged along the second direction, and the solar cell further includes a first doped conductive layer and a second doped conductive layer, the first doped conductive layer is located in the fourth region and has a first doping type; the second doped conductive layer is located in the third region and has a second doping type, and the first doping type is opposite to the second doping type.

5. The solar cell according to claim 1, wherein The antireflection layer includes a first antireflection layer and a second antireflection layer, wherein the first antireflection layer is located between the ultraviolet absorption layer and the second antireflection layer, the refractive index of the first antireflection layer is 1.95 - 2.1, and the refractive index of the second antireflection layer is 1.75 - 1.

95.

6. The solar cell according to claim 1, wherein The refractive index of the ultraviolet absorption layer ranges from 2.25 to 2.

68.

7. The solar cell according to claim 1, characterized in that, The material of the ultraviolet absorption layer includes TiO2, wherein the atomic ratio of Ti to O is (1:1.7) - (1:2), the ultraviolet absorption layer includes a plurality of absorption sublayers, and in the first direction, the plurality of absorption sublayers are stacked in sequence, and the atomic ratio of Ti to O in the absorption sublayers decreases.

8. The solar cell according to claim 7, wherein The decreasing ratio of the atomic ratio of Ti to O in the absorption sublayers is 7% - 8%.

9. The solar cell according to claim 7, characterized in that, The atomic ratio of Ti in the absorption sublayer farthest from the silicon substrate to Si in the first antireflection layer of the antireflection layer is (1:6) - (1:5).

10. A method for preparing a solar cell, characterized in that, For preparing the solar cell according to any one of claims 1 to 9, the preparation method includes: Providing a silicon substrate; Adopting a first deposition process to control the flow rate ratio of a titanium precursor source and an oxidant to gradually decrease, and forming an ultraviolet absorption layer on one side of the silicon substrate; Adopting a second deposition process to form an antireflection layer on the ultraviolet absorption layer.

11. The preparation method according to claim 10, characterized in that, The flow rate ratio of the titanium precursor source and the oxidant is (1:5) - (1:8).

12. The preparation method according to claim 10, characterized in that, The temperature of the second deposition process is 400°C - 500°C.

13. The preparation method according to claim 10, characterized in that, Before forming the ultraviolet absorption layer, a field passivation layer is formed on the silicon substrate by an atomic layer deposition process, wherein the temperature of the atomic layer deposition process is 250°C - 300°C.

14. A stacked battery, characterized in that, Comprising: The bottom cell is the solar cell according to any one of claims 1 to 9, or the solar cell prepared by the preparation method of the solar cell according to any one of claims 10 to 13; The top cell is located on the bottom cell.

15. A photovoltaic module, characterized in that, It includes: A battery string, which is formed by connecting multiple solar cells according to any one of claims 1 to 9, or formed by connecting multiple solar cells prepared by the preparation method of the solar cell according to any one of claims 10 to 13, or formed by connecting multiple tandem cells according to claim 14; An encapsulation adhesive film for covering the surface of the battery string; A cover plate for covering the surface of the encapsulation adhesive film facing away from the battery string.

Images