Photovoltaic cell and method of manufacturing the same, photovoltaic module

Abstract

The present disclosure relates to the field of photovoltaics, and provides a photovoltaic cell, a manufacturing method thereof, and a photovoltaic module. The photovoltaic cell comprises: a substrate having a first surface and a second surface opposite along a first direction, the first direction being a thickness direction of the substrate; the first surface comprises a plurality of first regions and a plurality of second regions, a surface topography of the first regions comprises a first pyramid structure, and a surface topography of the second regions is a polished surface; a passivation contact structure is located on the first surface and / or the second surface, a surface topography of a region opposite to the first regions on a side of the passivation contact structure away from the substrate comprises the first pyramid structure, and a surface topography of a region opposite to the second regions on the side of the passivation contact structure away from the substrate is the polished surface; and an electrode is located on the side of the passivation contact structure away from the substrate, and a single electrode is located on at least one first region and at least one second region, so as to at least facilitate improving the reflectivity of the first surface while ensuring that the first surface has a suitable roughness to facilitate the adhesion of the electrode on the first surface.

Description

Technical Field

[0001] This disclosure relates to the photovoltaic field, and in particular to a photovoltaic cell and its manufacturing method, and a photovoltaic module. Background Technology

[0002] With the rapid development of solar photovoltaic technology, photovoltaic cells are becoming increasingly widely used as a sustainable and clean energy source. A photovoltaic cell is a device that uses the photovoltaic principle to generate charge carriers to convert solar energy into electrical energy. Electrodes are typically used in photovoltaic cells to extract these charge carriers, thus efficiently utilizing the electrical energy. Currently, the mainstream types of photovoltaic cells include BC cells (Back Contact), TOPCON (Tunnel Oxide Passivated Contact), PERC cells (Passivated emitter and real cell), and heterojunction cells (Heterojunction with Intrinsic Thin-film, abbreviated as HIT or HJT).

[0003] However, due to the varying light utilization requirements and surface roughness requirements of different film layers, different surface morphologies are needed for different surfaces or different regions of the same surface, in order to ultimately improve the overall photoelectric conversion efficiency of photovoltaic cells. Therefore, further research is needed on the surface morphology of some film layers in photovoltaic cells. Summary of the Invention

[0004] This disclosure provides a photovoltaic cell and its manufacturing method, as well as a photovoltaic module, which at least helps to improve the reflectivity of the first surface while ensuring that the first surface has a suitable roughness to facilitate the adhesion of electrodes on the first surface.

[0005] This disclosure provides a photovoltaic cell, comprising: a substrate having a first surface and a second surface opposite to each other along a first direction, the first direction being the thickness direction of the substrate; the first surface including a plurality of first regions and a plurality of second regions, the surface morphology of the first regions including a first pyramid structure, and the surface morphology of the second regions being a polished surface; a passivation contact structure located on the first surface and / or the second surface, wherein on the surface of the passivation contact structure on the side away from the substrate, the surface morphology of the region opposite to the first region includes the first pyramid structure, and the surface morphology of the region opposite to the second region is the polished surface; and an electrode located on the side of the passivation contact structure away from the substrate, wherein a single electrode is located on at least one first region and at least one second region.

[0006] Optionally, the surface morphology of at least a portion of the first region may further include a second pyramid structure; wherein the base size of the second pyramid structure is smaller than the base size of the first pyramid structure, and the height of the second pyramid structure is smaller than the height of the first pyramid structure along the first direction.

[0007] Optionally, the base size of the first pyramid structure is 0.5μm to 1.3μm, and the height of the first pyramid structure is 0.5μm to 0.7μm; the base size and the height of the second pyramid structure are both less than 0.3μm.

[0008] Optionally, the ratio of the area of ​​the region with the second pyramid structure in the first surface to the area of ​​the entire first surface is 4% to 6%.

[0009] Optionally, the surface morphology of the second surface includes a third pyramid structure, wherein the base size of the third pyramid structure is larger than the base size of the first pyramid structure.

[0010] Optionally, the base size of the third pyramid structure is 2.5μm to 3.5μm.

[0011] Optionally, the surface morphology of the second surface may further include a protrusion structure located on the side and / or side edge of the third pyramid structure, and the height of the protrusion structure is less than the height of the third pyramid structure along the first direction.

[0012] Optionally, the ratio of the base size of the first pyramid structure to the height of the first pyramid structure is 1.5 to 2.

[0013] Optionally, the ratio of the area of ​​the region with the first pyramid structure in the first surface to the area of ​​the entire first surface is 35% to 50%.

[0014] Optionally, the substrate further has a side surface connecting the first surface and the second surface; the side surface includes a plurality of third regions and a plurality of fourth regions, the surface morphology of the third region includes a fourth pyramid structure, and the surface morphology of the fourth region is the polished surface; wherein, the base size of the fourth pyramid structure is smaller than the base size of the first pyramid structure, and along the first direction, the height of the fourth pyramid structure is smaller than the height of the first pyramid structure.

[0015] Optionally, the base size of the fourth pyramid structure is 0.5μm~1μm, and the height of the fourth pyramid structure is 0.3μm~0.6μm.

[0016] Optionally, the area of ​​the region with the fourth pyramid structure on the side is 20% to 40% of the area of ​​the entire side.

[0017] Optionally, the reflectivity of the first surface is 20% to 25%.

[0018] Optionally, the top of the first pyramid structure is curved.

[0019] Optionally, the passivated contact structure includes: a dielectric layer located on the first surface and / or the second surface; a doped layer located on the side of the dielectric layer away from the substrate; the electrode is a first electrode, and the photovoltaic cell further includes: a second electrode located on the second surface.

[0020] Optionally, the first surface includes a fifth region and a sixth region arranged alternately along a second direction; the passivation contact structure includes a first passivation contact structure located in the fifth region and a second passivation contact structure located in the sixth region; the electrode includes a first electrode located on the side of the first passivation contact structure away from the substrate and a second electrode located on the side of the second passivation contact structure away from the substrate.

[0021] This disclosure also provides a method for manufacturing a photovoltaic cell, comprising: forming a substrate having a first surface and a second surface opposite to each other along a first direction, the first direction being the thickness direction of the substrate; the first surface including a plurality of first regions and a plurality of second regions, the surface morphology of the first regions including a first pyramid structure, and the surface morphology of the second regions being a polished surface; forming a passivation contact structure on the first surface and / or the second surface, wherein on the side of the passivation contact structure away from the substrate, the surface morphology of the region opposite to the first region includes the first pyramid structure, and the surface morphology of the region opposite to the second region is the polished surface; forming an electrode on the side of the passivation contact structure away from the substrate, and a single electrode being located on at least one first region and at least one second region.

[0022] Optionally, the step of forming the substrate includes: providing an initial substrate having an initial first surface and an initial second surface facing each other in a first direction; treating the initial first surface with a first solution to transform the initial first surface into an initial polished surface; treating the initial polished surface with a second solution to transform a portion of the initial polished surface into a first region with a surface morphology including the first pyramid structure, and transforming other regions of the initial polished surface into a second region with a surface morphology of the polished surface; wherein the first solution and the second solution are both alkaline solutions, and the alkalinity of the first solution is less than that of the second solution.

[0023] Optionally, the reflectivity of the initial polished surface is 35% to 40%; and / or, the initial polished surface includes an initial tower base structure, the size of which is 10 μm to 15 μm.

[0024] Optionally, the process temperature of the first solution is lower than that of the second solution; and / or, the processing time of the first solution is shorter than that of the second solution.

[0025] Optionally, before using the first solution, the method for manufacturing the photovoltaic cell further includes: treating the initial first surface with at least a third solution to transform the initial first surface into an initial first textured surface including a fifth pyramid structure; in the step of using the first solution, at least the top of the fifth pyramid structure is removed to transform the initial first textured surface into the initial polished surface.

[0026] Optionally, the third solution is an alkaline solution, and the alkaline concentration of the third solution is less than that of the second solution.

[0027] Optionally, the initial second surface is further subjected to the second texturing process, so that the initial second surface is transformed into an initial second textured surface; after the second texturing process and before the polishing process, the method for manufacturing the photovoltaic cell further includes: performing a doping process to form at least a first diffusion layer and a first getter layer on the initial first textured surface, and forming a second diffusion layer and a second getter layer on the initial second textured surface; removing the first getter layer; in the polishing process, using the second getter layer as a mask to protect the initial second textured surface; and after the polishing process, removing the second getter layer.

[0028] Optionally, the initial substrate further has an initial side surface connecting the initial first surface and the initial second surface; in the step of using the first solution, the initial side surface is also treated with the first solution; in the step of using the second solution, the initial side surface is also treated with the second solution to form a side surface including a plurality of third regions and a plurality of fourth regions, wherein the surface morphology of the third region includes a fourth pyramid structure, the surface morphology of the fourth region is the polished surface, the base size of the fourth pyramid structure is smaller than the base size of the first pyramid structure, and along the first direction, the height of the fourth pyramid structure is smaller than the height of the first pyramid structure.

[0029] In another aspect, this disclosure provides a photovoltaic module, comprising: a battery string, formed by connecting a plurality of photovoltaic cells as described in any one of the preceding claims, or formed by connecting a plurality of photovoltaic cells formed by a manufacturing method of photovoltaic cells as described in any one of the preceding claims; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film opposite to the battery string.

[0030] The technical solution provided in this disclosure has at least the following advantages: On the one hand, the surface morphology of the first region of the first surface includes a first pyramid structure, meaning that a portion of the first surface has a textured surface. This improves the roughness of the first surface, enhancing the adhesion strength of the electrodes when they are placed on it. In other words, the electrodes can be more firmly mounted on the first surface, improving the structural stability and yield of the photovoltaic cell. On the other hand, the surface morphology of the second region of the first surface is a polished surface, meaning that other regions of the first surface have a polished surface. This reduces the specific surface area of ​​the second region, thereby reducing carrier recombination on the first surface and increasing the open-circuit voltage of the photovoltaic cell. Furthermore, the polished surface enhances light reflection in the second region, thus increasing the short-circuit current of the photovoltaic cell. Therefore, by designing the surface morphology of the first surface to include both the first pyramid structure and the polished surface, the overall photoelectric conversion efficiency of the photovoltaic cell is improved, and the phenomenon of electrodes detaching from the photovoltaic cell is effectively prevented. Attached Figure Description

[0031] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this disclosure or the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a first partial cross-sectional schematic diagram of a photovoltaic cell provided in an embodiment of the present disclosure; Figure 2 A scanning electron microscope image of the first surface of a substrate in a photovoltaic cell provided in an embodiment of this disclosure; Figure 3 A cross-sectional schematic diagram of a first pyramid structure in a photovoltaic cell provided in an embodiment of this disclosure; Figure 4 This is a second partial cross-sectional schematic diagram of a photovoltaic cell provided in an embodiment of the present disclosure; Figure 5A scanning electron microscope image of the second surface of a substrate in a photovoltaic cell provided in an embodiment of this disclosure; Figure 6 This is a partial cross-sectional schematic diagram of a substrate in a photovoltaic cell provided in an embodiment of the present disclosure; Figure 7 A scanning electron microscope image of the side surface of a substrate in a photovoltaic cell provided in an embodiment of this disclosure; Figure 8 This is a third partial cross-sectional schematic diagram of a photovoltaic cell provided in an embodiment of the present disclosure; Figure 9 This is a fourth partial cross-sectional schematic diagram of a photovoltaic cell provided in an embodiment of the present disclosure; Figure 10 This is a fifth partial cross-sectional schematic diagram of a photovoltaic cell provided in an embodiment of the present disclosure; Figure 11 A process flow diagram of a method for manufacturing a photovoltaic cell according to another embodiment of this disclosure; Figure 12 A partial cross-sectional schematic diagram of a substrate formed in a method for manufacturing a photovoltaic cell according to another embodiment of this disclosure; Figure 13 This is a partial cross-sectional schematic diagram of the initial substrate in a method for manufacturing a photovoltaic cell according to another embodiment of the present disclosure; Figure 14 A scanning electron microscope image of the initial polished surface in a method for manufacturing a photovoltaic cell according to another embodiment of this disclosure; Figure 15 A partial cross-sectional schematic diagram of a photovoltaic cell manufacturing method provided in another embodiment of this disclosure after treating the initial substrate with a third solution; Figure 16 A partial cross-sectional schematic diagram of a photovoltaic cell manufacturing method according to another embodiment of this disclosure after doping treatment; Figure 17 This is a partial cross-sectional view of a photovoltaic cell manufacturing method provided in another embodiment of the present disclosure after removing the first getter layer; Figure 18 This is a partial cross-sectional schematic diagram of a photovoltaic cell manufacturing method provided in another embodiment of the present disclosure after removing the second getter layer; Figure 19 A partial three-dimensional schematic diagram of a cell string in a photovoltaic module provided in yet another embodiment of this disclosure; Figure 20 This is a partial cross-sectional schematic diagram of a photovoltaic module provided in yet another embodiment of the present disclosure.

[0033] Explanation of reference numerals in the attached figures: 100, Substrate; 1001, First Surface; 1002, Second Surface; 1003, Side Surface; 110, First Region; 120, Second Region; 1201, Polished Surface; 130, Third Region; 140, Fourth Region; 150, Fifth Region; 160, Sixth Region; 101, First Pyramid Structure; 102, Passivated Contact Structure; 112, Dielectric Layer; 1121, First Dielectric Layer; 1122, Second Dielectric Layer; 122, Doped Layer; 1221, First Doped Layer; 1222, Second Doped Layer; 132, First Passivated Contact Structure; 1321, First Passivation Section; 1322, First Doped Section; 142, Second Passivated Contact Structure; 1421, Second Passivation Section; 1422, Second Doped Section; 03. Electrode; 113. First electrode; 123. Second electrode; 133. Transparent conductive film; 104. Second pyramid structure; 105. Third pyramid structure; 106. Protruding structure; 107. Fourth pyramid structure; 108. Initial substrate; 1081. Initial first surface; 1082. Initial second surface; 1083. Initial side surface; 118. Initial polished surface; 128. Initial pyramid base structure; 138. Initial first textured surface; 1381. Fifth pyramid structure; 148. Initial second textured surface; 109. First diffusion layer; 119. First getter layer; 129. Second diffusion layer; 139. Second getter layer; 40. Photovoltaic cell; 41. Encapsulating film; 42. Cover plate; 43. Solder ribbon. Detailed Implementation

[0034] As can be seen from the background technology, in order to comprehensively improve the photoelectric conversion efficiency of photovoltaic cells, the surface morphology of some films in photovoltaic cells needs further research.

[0035] This disclosure provides a photovoltaic cell and its manufacturing method, as well as a photovoltaic module. In the photovoltaic cell, on one hand, the surface morphology of a first region of the first surface is designed to include a first pyramid structure, that is, the surface morphology of a portion of the first surface is designed to be textured, which helps to improve the roughness of the first surface, thereby improving the adhesion strength of the electrodes when they are placed on the first surface. In other words, the electrodes can be more firmly placed on the first surface, thereby improving the structural stability and yield of the photovoltaic cell. On the other hand, the surface morphology of a second region of the first surface is designed to be a polished surface, that is, the surface morphology of other regions of the first surface is designed to be polished, which helps to reduce the specific surface area of ​​the second region, thereby reducing the recombination of charge carriers on the first surface, thereby improving the open-circuit voltage of the photovoltaic cell. Moreover, the polished surface can enhance the reflection effect of light in the second region, thereby increasing the short-circuit current of the photovoltaic cell. Thus, the surface morphology of the first surface includes both a first pyramid structure and a polished surface, which helps to comprehensively improve the photoelectric conversion efficiency of the photovoltaic cell and effectively avoid the phenomenon of electrodes detaching from the photovoltaic cell.

[0036] In the description of the embodiments of this disclosure, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary or secondary relationship of the indicated technical features. In the description of the embodiments of this disclosure, "a plurality of" means two or more, unless otherwise explicitly defined.

[0037] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this disclosure. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0038] In the description of the embodiments of this disclosure, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0039] In the description of embodiments of this disclosure, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0040] In the description of the embodiments of this disclosure, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this disclosure and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this disclosure.

[0041] In the description of the embodiments of this disclosure, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0042] In the accompanying drawings corresponding to the embodiments of this disclosure, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0043] In the description of embodiments of this disclosure, when a component "includes" another component, other components are not excluded unless otherwise stated, and may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may be present therein. Additionally, when a component such as a layer, film, region, or plate is "directly located" on another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it indicates that no other components are located therein.

[0044] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "component" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0045] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this disclosure to facilitate a better understanding of the embodiments. However, the technical solutions claimed in the embodiments of this disclosure can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0046] This disclosure provides a photovoltaic cell according to one embodiment. The photovoltaic cell provided by this disclosure will be described in detail below with reference to the accompanying drawings.

[0047] Reference Figure 1 and Figure 2The photovoltaic cell includes: a substrate 100 having a first surface 1001 and a second surface 1002 opposite to each other along a first direction X, the first direction X being the thickness direction of the substrate 100; the first surface 1001 includes a plurality of first regions 110 and a plurality of second regions 120, the surface morphology of the first region 110 including a first pyramid structure 101, and the surface morphology of the second region 120 being a polished surface 1201; a passivation contact structure 102 located on the first surface 1001 and / or the second surface 1002; and an electrode 103 located on the side of the passivation contact structure 102 away from the substrate 100, with a single electrode 103 located on at least one first region 110 and at least one second region 120.

[0048] Among them, the surface morphology of the area opposite to the first region 110 in the passivation contact structure 102 away from the substrate 100 includes the first pyramid structure 101, and the surface morphology of the area opposite to the second region 120 is the polished surface 1201.

[0049] Figure 1 This is a first partial cross-sectional schematic diagram of a photovoltaic cell provided in an embodiment of the present disclosure; Figure 2 A scanning electron microscope image of the first surface of a substrate in a photovoltaic cell provided in an embodiment of this disclosure.

[0050] It is worth noting that, on the one hand, the surface morphology of the first region 110 of the first surface 1001 includes a first pyramid structure 101, that is, the surface morphology of a portion of the first surface 1001 is designed to be a textured surface, which is beneficial to improving the roughness of the first surface 1001, thereby improving the adhesion strength of the electrode 103 when it is placed on the first surface 1001. In other words, the electrode 103 can be placed more firmly on the first surface 1001, thereby improving the structural stability and yield of the photovoltaic cell. On the other hand, the surface morphology of the second region 120 of the first surface 1001 is designed to be a polished surface 1201, that is, the surface morphology of other regions of the first surface 1001 is designed to be a polished surface 1201, which is beneficial to reducing the specific surface area of ​​the second region 120, thereby reducing the recombination of charge carriers on the first surface 1001, thereby improving the open-circuit voltage of the photovoltaic cell. Moreover, the polished surface 1201 can enhance the reflection effect of light in the second region 120, thereby improving the short-circuit current of the photovoltaic cell. Thus, the surface morphology of the first surface 1001 includes both the first pyramid structure 101 and the polished surface 1201, which is beneficial to comprehensively improve the photoelectric conversion efficiency of the photovoltaic cell and effectively avoid the phenomenon of the electrode 103 falling off from the photovoltaic cell.

[0051] It should be noted that, compared to a conventional polished surface, the first surface 1001 designed in one embodiment of this disclosure has a higher roughness due to the presence of the first region 110 including the first pyramid structure 101, which can improve the connection strength between the portion of the electrode 103 disposed on the first region 110 and the first surface 1001. For example, in a conventional tensile test on the electrode 103, the tensile force exhibited by the electrode 103 disposed on the first surface 1001 is almost the same as the tensile force exhibited by the electrode disposed on a conventional textured surface.

[0052] Furthermore, compared to conventional textured surfaces, the first surface 1001 designed in one embodiment of this disclosure, due to the presence of the second region 120 of the polished surface 1201, can improve the uniformity of the thickness of the film layer disposed on the first surface 1001, such as the passivation contact structure 102, thereby enhancing the passivation effect on the substrate 100, and can also increase the reflectivity of the first surface 1001. Thus, the photoelectric conversion efficiency of the photovoltaic cell can be improved in multiple ways, and the firmness of the electrode 103 disposed on the first surface 1001 can be ensured, thereby improving the structural stability of the photovoltaic cell and the photovoltaic module subsequently formed based on the photovoltaic cell.

[0053] In some cases, during routine tensile tests on electrodes, the tensile force exhibited by the electrode 103 disposed on the first surface 1001 in an embodiment of this disclosure is almost the same as that exhibited by the electrode disposed on the conventional polished surface. However, the photoelectric conversion efficiency of the photovoltaic cell can be improved by at least 15%, which will be explained in detail later with specific experiments.

[0054] It should be noted that, to clearly illustrate the surface morphology characteristics of the first surface 1001, the division of the first region 110 and the second region 120 is based on the different surface morphologies of different areas of the first surface 1001. The first region 110 can be considered as a textured area of ​​the first surface 1001, and the second region 120 can be considered as a polished area of ​​the first surface 1001. In other words, the first region 110 and the second region 120 are divisions of the first surface 1001 rather than divisions of the entire substrate 100; that is, the first region 110 and the second region 120 are surfaces exhibiting different surface morphologies, but both belong to sub-parts of the first surface 1001. Moreover, based on the fabrication process of the first surface 1001, the arrangement of the first region 110 and the second region 120 in the first surface 1001 has a certain degree of disorder. That is, there is a certain degree of randomness in where the first pyramid structure 101 appears and where the polished surface 1201 appears in the first surface 1001. However, for the entire first surface 1001, since the size of the first pyramid structure 101 is at most at the single-digit micrometer level, which is at least one order of magnitude smaller than the size of the electrode 103 disposed on the first surface 1001, the electrode 103 will be located on at least one first region 110 and at least one second region 120 at the same time.

[0055] Furthermore, polished surface 1201 refers to a surface comprising multiple platform structures or tower base structures. For example, compared to the first region 110, which includes the first pyramid structure 101 and has a textured surface, the surface morphology of the second region 120 of polished surface 1201 is flatter, which is more conducive to improving the thickness uniformity of various films formed based on the second region 120, such as forming a passivation contact structure 102 with better film quality. The platform structures or tower base structures of polished surface 1201 can be considered as the base portion of a pyramid structure, meaning that polished surface 1201 includes multiple square tower base surfaces.

[0056] In some cases, the polished surface 1201 can be the surface formed after the substrate 100 is texturized to form a pyramid structure, and then polished to remove the apex of the pyramid structure during the polishing process. In other words, the polished surface 1201 includes the remaining structure after the apex of the pyramid structure has been removed; that is, the polished surface 1201 includes the remaining slightly raised platform structure or the base structure.

[0057] The photovoltaic cell provided in one embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0058] In some embodiments, reference Figure 1 The substrate 100 has a front and a back side, one of the first surface 1001 and the second surface 1002 is the front side and the other is the back side. The following description will use the first surface 1001 as the back side as an example.

[0059] In some cases, the photovoltaic cell can be a single-sided cell, in which case the front side of the substrate 100 can serve as the light-receiving surface to receive incident light, while the back side serves as the backlighting surface. In other cases, the photovoltaic cell can be a bifacial cell, in which case both the front and back sides of the substrate 100 can serve as light-receiving surfaces to receive incident light, with the front side being the primary light-receiving surface and the back side being the secondary light-receiving surface. It should be noted that, in one embodiment of this disclosure, the backlighting surface can also receive incident light, but its reception of incident light is weaker than that of the light-receiving surface, hence it is called the backlighting surface.

[0060] In some embodiments, reference Figure 1 and Figure 2 The reflectivity of the first surface 1001 can be 20% to 25%, for example, 20%, 21%, 22%, 23%, 24%, or 25%. Thus, although the emissivity of the entire first surface 1001 is lower than that of the polished surface 1201, it is higher than that of the textured surface. A reflectivity of 20% to 25% for the first surface 1001 can effectively increase the short-circuit current of the photovoltaic cell.

[0061] In some cases, the first surface 1001 is a backlight surface. The reflectivity of the first surface 1001 is 20% to 25%, which helps to emit more light into the interior of the substrate 100 and prevents the light from escaping through the substrate 100. This can improve the absorption and utilization rate of light by the substrate 100, thereby increasing the short-circuit current of the photovoltaic cell.

[0062] The first pyramid structure 101 will be described in detail below.

[0063] In some embodiments, in conjunction with reference Figure 1 and Figure 2The ratio of the base dimension to the height of the first pyramid structure 101 can be 1.5 to 2, for example, 1.5, 1.6, 1.7, 1.8, 1.9, or 2. This design, with a larger width-to-height ratio, facilitates the formation of a short and wide first pyramid structure 101. This results in a larger gap between adjacent first pyramid structures 101, which helps reduce the number of composite centers near the first pyramid structure 101 and is more conducive to the subsequent formation of a more uniformly thick passivation contact structure 102 on the first region 110. This, in turn, improves the roughness of the first region 110 while reducing the defect state density on the first surface 1001 and improving the film quality of the passivation contact structure 102. In other words, the connection strength between the electrode 103 and the first surface 1001 can be improved by using the first region 110, which has a roughness greater than that of the polished surface 1201, thereby improving the reliability of the photovoltaic cell. Furthermore, the passivation effect of the passivation contact structure 102 on the first surface 1001 can be improved by using the first pyramid structure 101 with a large aspect ratio, thereby reducing the number of recombination centers of charge carriers on the first surface 1001.

[0064] In some embodiments, in conjunction with reference Figure 1 and Figure 2 The ratio of the area of ​​the region with the first pyramid structure 101 in the first surface 1001 to the area of ​​the entire first surface 1001 can be 35% to 50%, for example, it can be 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, or 50%, etc.

[0065] It is worth noting that the first surface 1001 needs to simultaneously achieve high light reflectivity, facilitate the fabrication of the passivation contact structure 102, and enhance the connection strength with the electrode 103. Therefore, the area of ​​the region with the first pyramid structure 101 in the first surface 1001 needs to be appropriately controlled. If the ratio of this area to the total area of ​​the first surface 1001 is less than 35%, the number of first pyramid structures 101 that enhance the connection strength of the electrode 103 will be relatively small, increasing the risk of electrode 103 detachment. If the ratio is greater than 50%, the risk of carrier recombination on the first surface 1001 will increase. Thus, designing the ratio of the area with the first pyramid structure 101 in the first surface 1001 to the total area of ​​the first surface 1001 to be 35% to 50% is beneficial for ensuring a high connection strength between the electrode 103 and the first surface 1001 while improving the passivation effect of the passivation contact structure 102 on the first surface 1001, thereby simultaneously improving the stability, reliability, and photoelectric conversion efficiency of the photovoltaic cell.

[0066] In some embodiments, in conjunction with reference Figures 1 to 3 , Figure 3 This is a cross-sectional schematic diagram of a first pyramid structure in a photovoltaic cell provided in an embodiment of the present disclosure. The top of the first pyramid structure 101 can be an arc surface.

[0067] Understandably, for pyramidal textured structures, a sharp apex is detrimental to the formation of uniformly thick films on the textured surface, such as passivation contact structures, and also hinders the contact between the electrode and the textured surface. Furthermore, the apex is prone to becoming a significant carrier recombination center. Therefore, designing the top of the first pyramidal structure 101 to be curved not only directly reduces the number of recombination centers near the first pyramidal structure 101, but also further improves the uniformity of the film thickness on the first surface 1001, such as the passivation contact structure 102, and enhances the electrical connection performance between the electrode 103 and the passivation contact structure 102. This can improve the photoelectric conversion efficiency of the photovoltaic cell in multiple ways.

[0068] The following describes in detail other characteristics of the surface morphology of the first surface 1001.

[0069] In some embodiments, reference Figure 2 The surface morphology of at least a portion of the first zone 110 may also include a second pyramid structure 104; wherein the base size of the second pyramid structure 104 may be smaller than the base size of the first pyramid structure 101, and the height of the second pyramid structure 104 may be smaller than the height of the first pyramid structure 101 along the first direction X.

[0070] It is understandable that there will be a large gap between some of the adjacent first pyramid structures 101, so a smaller second pyramid structure 104 can also be set in the first region 110. For example, a smaller second pyramid structure 104 can be designed between two first pyramid structures 101 that are far apart; or, a smaller second pyramid structure 104 can be designed at the junction of the first region 110 and the second region 120 or at the edge of the first region 110. In this way, it can be regarded that the smaller second pyramid structure 104 surrounds the first pyramid structure 101.

[0071] The smaller second pyramid structure 104 refers to the fact that the base size of the second pyramid structure 104 can be smaller than that of the first pyramid structure 101, and the height of the second pyramid structure 104 along the first direction X can be smaller than that of the first pyramid structure 101. Thus, on the one hand, the smaller second pyramid structure 104 will not significantly affect the reflectivity of the first surface 1001, and therefore will not reduce the light absorption and utilization efficiency of the photovoltaic cell; on the other hand, the cooperation between the first pyramid structure 101 and the second pyramid structure 104 helps to further improve the connection strength between the electrode 103 and the first surface 1001, thereby further improving the reliability of the photovoltaic cell.

[0072] In some cases, continue to refer to Figure 2 Multiple second pyramid structures 104 can be relatively scattered on the first region 110. In other words, there can also be spacing between adjacent second pyramid structures 104 to further reduce the risk of forming a composite center around the second pyramid structure 104, thereby further enhancing the electrode 103 (refer to...). Figure 1 While strengthening the connection between the first surface 1001 and the first surface 1001, the defect state density of the first surface 1001 is reduced, and the passivation contact structure 102 (see reference) provided on the first surface 1001 is ensured. Figure 1 Good passivation effect.

[0073] Thus, on the one hand, the smaller second pyramid structure 104 will not have a significant impact on the reflectivity of the first surface 1001, and it is also not easy to form around the second pyramid structure 104.

[0074] In some cases, in conjunction with references Figures 1 to 3 The base size W of the first pyramid structure 101 can be 0.5μm~1.3μm, and the height H of the first pyramid structure 101 can be 0.5μm~0.7μm; the base size and height of the second pyramid structure 104 can both be less than 0.3μm. It is evident that both the first pyramid structure 101 and the second pyramid structure 104 are relatively small pyramid structures to minimize the adverse effects of the first surface 1001 on the film quality of the passivation contact structure 102, and to maximize the emissivity of the first surface 1001. Furthermore, the combination of large and small sizes further enhances the connection strength between the electrode 103 and the first surface 1001.

[0075] In some examples, the base size W of the first pyramid structure 101 can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm or 1.3μm, etc.

[0076] In some examples, the height H of the first pyramid structure 101 can be 0.5μm, 0.55μm, 0.6μm, 0.65μm or 0.7μm, etc.

[0077] In some examples, the base size or height of the second pyramid structure 104 can be 0.29μm, 0.28μm, 0.27μm, 0.26μm, 0.25μm, 0.24μm, 0.23μm, 0.22μm, 0.21μm, or 0.2μm, etc.

[0078] In some cases, refer to Figure 1 and Figure 2 The ratio of the area of ​​the region with the second pyramid structure 104 in the first surface 1001 to the area of ​​the entire first surface 1001 can be 4% to 6%, for example, it can be 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9% or 6%, etc.

[0079] It is worth noting that the first surface 1001 needs to simultaneously achieve high reflectivity of light, facilitate the fabrication of the passivation contact structure 102, and enhance the connection strength with the electrode 103. Therefore, it is necessary to appropriately control the area of ​​the region with the second pyramid structure 104 in the first surface 1001. If the ratio of this area to the area of ​​the entire first surface 1001 is less than 4%, the auxiliary gain provided by the second pyramid structure 104 to the first pyramid structure 101 is limited, and its effect on improving the connection strength of the electrode 103 is limited. If the ratio of this area to the area of ​​the entire first surface 1001 is greater than 6%, the arrangement density of the first pyramid structure 101 and the second pyramid structure 104 in the first region 110 will be too high, which will easily increase the risk of carrier recombination in the first region 110. Thus, the area of ​​the region with the second pyramid structure 104 in the first surface 1001 is designed to be 4% to 6% of the total area of ​​the first surface 1001. This helps to ensure that the second pyramid structure 104 plays a good auxiliary role in the connection strength of the electrode 103, and avoids the addition of the second pyramid structure 104 from increasing the number of composite centers on the first surface 1001, as well as from reducing the emissivity of the first surface 1001.

[0080] The surface morphology of the second surface 1002 is described in detail below.

[0081] In some embodiments, in conjunction with reference Figure 4 and Figure 5The surface morphology of the second surface 1002 may include a third pyramid structure 105. The base size of the third pyramid structure 105 may be larger than the base size of the first pyramid structure 101. The first direction X is the thickness direction of the base 100.

[0082] in, Figure 4 This is a second partial cross-sectional schematic diagram of a photovoltaic cell provided in an embodiment of the present disclosure; Figure 5 A scanning electron microscope image of the second surface of a substrate in a photovoltaic cell provided in an embodiment of this disclosure.

[0083] It is worth noting that, unlike the first surface 1001 where only a portion, i.e., the first region 110, includes the first pyramid structure 101, the entire surface of the second surface 1002 is a textured surface comprising multiple third pyramid structures 105. Therefore, for the entire second surface 1002, designing third pyramid structures 105 with larger base sizes is more beneficial for improving the light-trapping effect of the second surface 1002, thereby increasing the light absorption and utilization rate of the second surface 1002. Furthermore, the larger base sizes of the third pyramid structures 105 are more beneficial for reducing the roughness differences between different regions of the second surface 1002, which in turn helps improve the uniformity of the thickness of the film layer formed on the second surface 1002, such as the second passivation contact structure 102, thus enhancing the passivation effect on the second surface 1002. In addition, the larger base sizes of the third pyramid structures 105 help increase the specific surface area of ​​the second surface 1002, which in turn helps increase the contact area between the electrode 103 and the second surface 1002, thereby improving the connection strength between the electrode 103 and the second surface 1002.

[0084] In some cases, the top of the third pyramid structure 105 can be an arc surface, which can not only directly reduce the number of composite centers near the third pyramid structure 105, but also further improve the film layer disposed on the second surface 1002, such as the thickness uniformity of the passivation contact structure 102, and improve the electrical connection performance between the electrode 103 and the passivation contact structure 102. In this way, the photoelectric conversion efficiency of the photovoltaic cell can be improved in many ways.

[0085] In some cases, the base size of the third pyramid structure 105 can be 2.5μm to 3.5μm, for example, it can be 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, 3.1μm, 3.2μm, 3.3μm, 3.4μm or 3.5μm, etc.

[0086] In some cases, continue to combine references Figure 4 and Figure 5The surface morphology of the second surface 1002 may further include a protrusion structure 106, which is located on the side and / or side edge of the third pyramid structure 105 and along the first direction X. The height of the protrusion structure 106 is less than the height of the third pyramid structure 105. In other words, the surface morphology of the second surface 1002 includes not only the third pyramid structure 105 but also the protrusion structure 106, which surrounds the third pyramid structure 105.

[0087] Thus, the protruding structures 106 on the sides and / or side edges of the third pyramid structure 105 and the third pyramid structure 105 can be considered to jointly constitute a clustered pyramid group, which is beneficial for forming more light-trapping areas to improve the light-trapping effect of the second surface 1002. Moreover, the clustered pyramid group makes the second surface 1002 rougher, which is more conducive to improving the connection strength between the electrode 103 and the second surface 1002, thereby improving the reliability and photoelectric conversion efficiency of the photovoltaic cell. In other words, compared with a conventional textured surface, such as a textured surface that only includes pyramid structures, the height difference inside the clustered pyramid group jointly formed by the protruding structures 106 and the third pyramid structure 105 is smaller, or the unevenness per unit area is lower. This is more conducive to improving the formation quality of the passivation contact structure 102 and / or the electrode 103. Furthermore, the clustered pyramid group makes more effective use of the gaps between adjacent third pyramid structures 105, increasing the density and compactness of the textured surface, reducing the reflectivity of the second surface 1002, which is more conducive to the passivation and current improvement of the photovoltaic cell, thereby achieving the effect of improving the photoelectric performance of the photovoltaic cell.

[0088] Furthermore, compared to the first pyramid structure 101, the second pyramid structure 104, with its larger base size, is more likely to have more protruding structures 106 attached around it, thereby forming a larger cluster of pyramids. This is more conducive to improving the light trapping effect of the second surface 1002 and enhancing the firmness of the electrodes 103 disposed on the second surface 1002.

[0089] It should be noted that the reference Figure 4 and Figure 5At least a portion of the protruding structures 106 can be considered as incomplete pyramid structures. For example, the protruding structure 106 can be considered as a sheet-like pyramid structure. Along the direction from the apex to the base, the portion of the protruding structure 106 near the base is blocked by the side and / or side edges of the third pyramid structure 105 during its extension. This results in a smaller extension area on the side of the protruding structure 106 that contacts the third pyramid structure 105, thus presenting a protruding structure 106 with a apex but not a complete pyramid structure overall. Furthermore, in addition to contacting the third pyramid structure 105, a portion of the protruding structures 106 may also contact another protruding structure 106 on the other side. In other words, at least two protruding structures 106 can be stacked on the surface of the same third pyramid structure 105, making the protruding structure 106 more closely resemble a sheet-like structure.

[0090] Based on this, the base size of the protruding structure 106 can be understood as the base size when the protruding structure 106 extends into a complete pyramid structure without being blocked by the third pyramid structure 105, and the base size of the protruding structure 106 can be smaller than the base size of the third pyramid structure 105.

[0091] In some cases, the reflectivity of the second surface 1002 is below 10%, which is lower than that of the conventional textured surface that only includes a pyramid structure, making it more conducive to achieving better light trapping effect.

[0092] The surface morphology of the side surface 1003 of the substrate 100 is described in detail below.

[0093] In some embodiments, in conjunction with reference Figure 6 and Figure 7 The base 100 may also have a side 1003 connecting the first surface 1001 and the second surface 1002; the side 1003 may include a plurality of third regions 130 and a plurality of fourth regions 140, the surface morphology of the third region 130 may include a fourth pyramid structure 107, and the side 1003 located in the fourth region 140 is a polished surface 1201; wherein, the base size of the fourth pyramid structure 107 is smaller than the base size of the first pyramid structure 101, and along the first direction X, the height of the fourth pyramid structure 107 is smaller than the height of the first pyramid structure 101.

[0094] in, Figure 6 This is a partial cross-sectional schematic diagram of a substrate in a photovoltaic cell provided in an embodiment of the present disclosure; Figure 7 A scanning electron microscope (SEM) image of the side of a substrate in a photovoltaic cell provided in an embodiment of this disclosure.

[0095] It is worth noting that, to avoid leakage at side 1003, a passivation film layer (not shown in the figure) is usually formed on side 1003 to reduce the defect state density of side 1003. Based on this, side 1003 is designed to include a third region 130 and a fourth region 140 with different surface morphologies. Thus, compared to a conventional textured surface, the thickness uniformity of the passivation film layer on side 1003 can be improved by using the polished fourth region 140, thereby enhancing its passivation effect on side 1003. This prevents recombination of charge carriers at side 1003, reducing the risk of leakage at side 1003, and also improves the UV resistance of side 1003. Furthermore, the fourth pyramid structure 107 included in the third region 130 helps to improve the robustness of the passivation film layer on side 1003, thereby improving the reliability of the photovoltaic cell.

[0096] It should be noted that, to clearly illustrate the surface morphology characteristics of side surface 1003, the division of the third region 130 and the fourth region 140 is based on the different surface morphologies of different areas of side surface 1003. The third region 130 can be considered as a textured area of ​​side surface 1003, and the fourth region 140 can be considered as a polished surface 1201 area of ​​side surface 1003. In other words, the third region 130 and the fourth region 140 are divisions of side surface 1003 rather than divisions of the entire substrate 100; that is, the third region 130 and the fourth region 140 are surfaces with different surface morphologies, but both belong to sub-parts of side surface 1003. Moreover, based on the fabrication process of side surface 1003, the arrangement of the third region 130 and the fourth region 140 in side surface 1003 exhibits a certain degree of disorder; that is, the location of the fourth pyramid structure 107 and the location of the polished surface 1201 in side surface 1003 are somewhat random.

[0097] In some cases, the top of the fourth pyramid structure 107 can be an arc surface, which can not only directly reduce the number of recombination centers near the fourth pyramid structure 107, but also further improve the thickness uniformity of the film layer set on the side 1003, and further reduce the risk of carrier recombination on the side 1003.

[0098] In some cases, the base size of the fourth pyramid structure 107 can be 0.5μm to 1μm, for example, it can be 0.5μm, 0.55μm, 0.6μm, 0.65μm, 0.7μm, 0.75μm, 0.8μm, 0.85μm, 0.9μm, 0.95μm or 1μm, etc.; the height of the fourth pyramid structure 107 can be 0.3μm to 0.6μm, for example, it can be 0.3μm, 0.35μm, 0.4μm, 0.45μm, 0.5μm, 0.55μm or 0.6μm, etc.

[0099] In some cases, the ratio of the area of ​​the region with the fourth pyramid structure 107 in the side 1003 to the area of ​​the entire side 1003 can be 20% to 40%, for example, it can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%, etc.

[0100] It is worth noting that the side surface 1003 needs to simultaneously facilitate the formation of the passivation film and enhance the connection strength between the passivation film and the side surface 1003. Therefore, the area of ​​the region with the fourth pyramid structure 107 in the side surface 1003 needs to be appropriately controlled. If the ratio of this area to the total area of ​​the side surface 1003 is less than 20%, the number of fourth pyramid structures 107 that enhance the connection strength of the passivation film is relatively small, increasing the risk of passivation film detachment. If the ratio of this area to the total area of ​​the side surface 1003 is greater than 40%, the risk of carrier recombination on the side surface 1003 increases. Thus, designing the ratio of the area with the fourth pyramid structure 107 in the side surface 1003 to the total area of ​​the side surface 1003 to be 20% to 40% is beneficial for ensuring a high connection strength between the passivation film and the side surface 1003 while improving the passivation effect of the passivation film on the side surface 1003, thereby simultaneously improving the stability, reliability, and photoelectric conversion efficiency of the photovoltaic cell.

[0101] The passivated contact structure 102 will be described in detail below in conjunction with the specific type of photovoltaic cell.

[0102] In some embodiments, reference Figure 8 or Figure 9 The photovoltaic cell is a cell with electrodes on both sides, such as TOPCON cells, PERC cells, or heterojunction cells. Thus, the passivation contact structure 102 may include: a dielectric layer 112 located on the first surface 1001 and / or the second surface 1002; a doped layer 122 located on the side of the dielectric layer 112 away from the substrate 100; and an electrode 103, which is the first electrode 113. The photovoltaic cell may also include: a second electrode 123 located on the second surface 1002.

[0103] in, Figure 8 This is a third partial cross-sectional schematic diagram of a photovoltaic cell provided in an embodiment of the present disclosure; Figure 9 This is a fourth partial cross-sectional schematic diagram of a photovoltaic cell provided in an embodiment of this disclosure. It should be noted that... Figure 8 and Figure 9 The image is intended to illustrate the relationship between the passivated contact structure 102 and the photovoltaic cell type, but the surface morphology of the first surface 1001 and the second surface 1002 of the substrate 100 is not clearly shown.

[0104] In some cases, refer to Figure 8 The photovoltaic cell can be an HJT cell; the dielectric layer 112 may include a first dielectric layer 1121 located on the first surface 1001 and a second dielectric layer 1122 located on the second surface 1002; the doped layer 122 may include a first doped layer 1221 located on the side of the first dielectric layer 1121 away from the substrate 100 and a second doped layer 1222 located on the side of the second dielectric layer 1122 away from the substrate 100, and one of the first doped layer 1221 and the second doped layer 1222 is doped with a P-type dopant element and the other is doped with an N-type dopant element.

[0105] In some examples, the materials of the first dielectric layer 1121 and the second dielectric layer 1122 may both include one or more of amorphous silicon, microcrystalline silicon, or nanocrystalline silicon, and the materials of the first doped layer 1221 and the second doped layer 1222 may both include single-crystal, polycrystalline, amorphous, or microcrystalline silicon material layers.

[0106] In some examples, the P-type dopant can be at least one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or gallium (In); the N-type dopant can be at least one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As).

[0107] In some examples, continue to refer to Figure 8 The HJT battery may also include: a transparent conductive film 133 located between the first electrode 113 and the first doped layer 1221, and located between the second electrode 123 and the second doped layer 1222.

[0108] In other cases, refer to Figure 9 The photovoltaic cell can be a TOPCON cell, and the dielectric layer 112 can be located on the first surface 1001.

[0109] In some examples, the material of the dielectric layer 112 may include one or more of silicon oxide, silicon carbide, silicon nitride, or silicon oxynitride; the material of the doped layer 122 may include a single-crystal, polycrystalline, amorphous, or microcrystalline silicon material layer, and the doped layer 122 is doped with a P-type dopant or an N-type dopant.

[0110] In some examples, the TOPCON cell may also include: an emitter structure (not shown) located on the second surface 1002, wherein one of the doped layer 122 and the emitter structure is doped with a P-type dopant and the other is doped with an N-type dopant.

[0111] In other embodiments, reference is made to Figure 10The photovoltaic cell is a cell with an electrode on one side only, such as a BC cell. Thus, the first surface 1001 may also include a fifth region 150 and a sixth region 160 arranged alternately along the second direction Y; the passivation contact structure 102 includes a first passivation contact structure 132 located in the fifth region 150 and a second passivation contact structure 142 located in the sixth region 160; the electrode 103 may include a first electrode 113 located on the side of the first passivation contact structure 132 away from the substrate 100 and a second electrode 123 located on the side of the second passivation contact structure 142 away from the substrate 100.

[0112] in, Figure 10 This is a fifth partial cross-sectional view of a photovoltaic cell provided in an embodiment of this disclosure. It should be noted that... Figure 10 The image is intended to illustrate the relationship between the passivated contact structure 102 and the photovoltaic cell type, but the surface morphology of the first surface 1001 and the second surface 1002 of the substrate 100 is not clearly shown.

[0113] In some cases, the first passivation contact structure 132 may include a first passivation portion 1321 located in the fifth region 150, and a first doped portion 1322 located away from the fifth region 150; the first electrode 113 is electrically connected to the first doped portion 1322; the second passivation contact structure 142 may include a second passivation portion 1421 located in the sixth region 160, and a second doped portion 1422 located away from the sixth region 160; the second electrode 123 is electrically connected to the second doped portion 1422.

[0114] In some examples, the material of at least one of the first passivation portion 1321 and the second passivation portion 1421 may include one or more of silicon oxide, silicon carbide, silicon nitride, and silicon oxynitride; in other examples, the material of at least one of the first passivation portion 1321 and the second passivation portion 1421 may include one or more of amorphous silicon, microcrystalline silicon, and nanocrystalline silicon.

[0115] It should be noted that BC cells include, but are not limited to, IBC cells (Interdigitated Back Contact, cross-junction back contact cells), HBC cells (Heterojunction Back Contact, heterojunction back contact cells), TBC cells (TOPCon Back Contact, cross-passivated back contact cells), or HTBC cells (Hybrid Passivated Back Contact, hybrid passivated back contact cells). Among them, HTBC cells are heterojunction and tunnel oxide passivated contact hybrid passivated back contact photovoltaic cells (abbreviated as HTBC).

[0116] In summary, on the one hand, the surface morphology of the first region 110 of the first surface 1001 includes a first pyramid structure 101, that is, the surface morphology of a portion of the first surface 1001 is designed to be a textured surface, which is beneficial to improving the roughness of the first surface 1001, thereby improving the adhesion strength of the electrode 103 when it is placed on the first surface 1001. In other words, the electrode 103 can be more firmly placed on the first surface 1001, thereby improving the structural stability and yield of the photovoltaic cell. On the other hand, the surface morphology of the second region 120 of the first surface 1001 is designed to be a polished surface 1201, that is, the surface morphology of other regions of the first surface 1001 is designed to be a polished surface 1201, which is beneficial to reducing the specific surface area of ​​the second region 120, thereby reducing the recombination of charge carriers on the first surface 1001, thereby improving the open-circuit voltage of the photovoltaic cell. Moreover, the polished surface 1201 can enhance the reflection effect of light in the second region 120, thereby improving the short-circuit current of the photovoltaic cell. Thus, the surface morphology of the first surface 1001 includes both the first pyramid structure 101 and the polished surface 1201, which is beneficial to comprehensively improve the photoelectric conversion efficiency of the photovoltaic cell and effectively avoid the phenomenon of the electrode 103 falling off from the photovoltaic cell.

[0117] This disclosure provides a method for manufacturing a photovoltaic cell according to an embodiment. The method for manufacturing a photovoltaic cell according to an embodiment of this disclosure will be described in detail below with reference to the accompanying drawings.

[0118] Reference Figures 1 to 18 , Figure 11 This is a process flow diagram of a method for manufacturing a photovoltaic cell according to another embodiment of the present disclosure. The method for manufacturing a photovoltaic cell includes at least the following steps: S1: Reference Figure 12 , Figure 12This is a partial cross-sectional schematic diagram of a substrate formed in a method for manufacturing a photovoltaic cell according to another embodiment of the present disclosure. A substrate 100 is formed, and the substrate 100 has a first surface 1001 and a second surface 1002 opposite to each other along a first direction X. The first surface 1001 includes a plurality of first regions 110 and a plurality of second regions 120. The surface morphology of the first region 110 includes a first pyramid structure 101, and the surface morphology of the second region 120 is a polished surface 1201.

[0119] S2: Refer to Figure 12 and Figure 1 A passivated contact structure 102 is formed on the first surface 1001 and / or the second surface 1002.

[0120] S3: Reference Figure 1 An electrode 103 is formed on the side of the passivated contact structure 102 away from the substrate 100, and a single electrode 103 is located on at least one first region 110 and at least one second region 120.

[0121] Thus, the surface morphology of the first surface 1001 includes both the first pyramid structure 101 and the polished surface 1201. On the one hand, this helps to reduce the defect state density of the first surface 1001, and the polished surface 1201 can be used to improve the thickness uniformity of the film layer subsequently formed on the first surface 1001, such as the passivation contact structure 102. On the other hand, it helps to improve the firmness of the electrode 103 that may be formed on the first surface 1001.

[0122] In some embodiments, reference Figures 13 to 18 Forming the substrate 100 may include the following steps: refer to Figure 13 An initial substrate 108 is provided, the initial substrate 108 having an initial first surface 1081 and an initial second surface 1082 opposite to each other in a first direction X; in conjunction with reference Figure 13 and Figure 14 The initial first surface 1081 is treated with a first solution to transform it into an initial polished surface 118; in conjunction with reference... Figure 14 and Figure 12 The initial polished surface 118 is treated with a second solution, which transforms a portion of the initial polished surface 118 into a first region 110 with a surface morphology including a first pyramid structure 101, and transforms other regions of the initial polished surface 118 into a second region 120 with a surface morphology of polished surface 1201; wherein, both the first solution and the second solution are alkaline solutions, and the alkaline concentration of the first solution is less than that of the second solution.

[0123] in, Figure 13This is a partial cross-sectional schematic diagram of the initial substrate in a method for manufacturing a photovoltaic cell according to another embodiment of the present disclosure; Figure 14 A scanning electron microscope image of the initial polished surface in a method for manufacturing a photovoltaic cell according to another embodiment of this disclosure.

[0124] The first solution is mainly used to polish the initial first surface 1081, and the resulting initial polished surface 118 lays the foundation for forming the second region 120, which is polished to full 1201. The second solution is mainly used to texturize a local area of ​​the initial polished surface 118, transforming the initial polished surface 118 into the first surface 1001. Therefore, based on the different roles played by the first and second solutions, the alkali concentration of the first solution is designed to be lower than that of the second solution. In particular, a higher alkali concentration in the second solution is more conducive to forming the first surface 1001, which simultaneously possesses the polished surface 1201 and the first pyramid structure 101.

[0125] The first solution will be described in detail below.

[0126] In some cases, the alkali in the first solution can be sodium hydroxide, the total volume of the first solution is 380L, and the content of sodium hydroxide in the first solution can be 1L to 2L, for example, 1L, 1.1L, 1.2L, 1.3L, 1.4L, 1.5L, 1.6L, 1.7L, 1.8L, 1.9L, or 2L, etc. In other cases, the alkali in the first solution can be potassium hydroxide, the total volume of the first solution is 380L, and the content of potassium hydroxide in the first solution can be 3L to 8L, for example, 3L, 3.5L, 4L, 4.5L, 5L, 5.5L, 6L, 6.5L, 7L, 7.5L, or 8L, etc.

[0127] In some cases, the first solution contains polishing additives. The total volume of the first solution is 380L. The content of polishing additives in the first solution can be 0.6L to 1L, for example, 0.6L, 0.65L, 0.7L, 0.75L, 0.8L, 0.85L, 0.9L, 0.95L or 1L, etc.

[0128] The second solution will be described in detail below.

[0129] In some cases, the alkali in the second solution can be sodium hydroxide, with a total volume of 380L and a sodium hydroxide content of 6L to 10L, for example, 6L, 6.5L, 7L, 7.5L, 8L, 8.5L, 9L, 9.5L, or 10L. In other cases, the alkali in the second solution can be potassium hydroxide, with a total volume of 380L and a potassium hydroxide content of 15L to 20L, for example, 15L, 15.5L, 16L, 16.5L, 17L, 17.5L, 18L, 18.5L, 19L, 19.5L, or 20L.

[0130] In some cases, the second solution contains the first texturing additive. The total volume of the second solution is 380L. The content of the first texturing additive in the second solution can be 1L to 3L, for example, 1L, 1.1L, 1.2L, 1.3L, 1.4L, 1.5L, 1.6L, 1.7L, 1.8L, 1.9L, 2L, 2.1L, 2.2L, 2.3L, 2.4L, 2.5L, 2.6L, 2.7L, 2.8L, 2.9L, or 3L, etc.

[0131] In one example, referring to Table 1, the alkali in the second solution can be sodium hydroxide. The following is a detailed explanation of the effect of the sodium hydroxide content in the second solution on the surface morphology of the final first surface 1001, based on a total volume of 380L.

[0132] Table 1: Effect of sodium hydroxide content in the second solution on the reflectivity of the first surface

[0133] It is worth noting that, in conjunction with reference Table 1 and Figures 12 to 14The surface morphology of the first surface 1001 directly affects its reflectivity. As shown in Table 1, the alkali concentration of the second solution has a significant impact on the surface morphology of the first surface 1001. With the increase of sodium hydroxide content in the second solution, the reflectivity of the first surface 1001 shows a trend of first rapidly decreasing, then increasing, and then decreasing again. Analysis revealed that when the sodium hydroxide content in the second solution was 0.5L, the initial polished surface 118 began to generate many small protrusions from its fully polished state, and the surface reflectivity rapidly decreased from 36% to about 20%. As the sodium hydroxide content in the second solution increased to 6.5L, a first surface 1001 was formed where the first pyramid structure 101 and the polished surface 1201 coexisted, with a reflectivity of 20% to 25%. However, when the sodium hydroxide content in the second solution was further increased to 9.5L, the first pyramid structure 101 became a pyramid structure with a larger base size, for example, a base size greater than 2μm, and the area ratio of the polished surface 1201 in the entire first surface 1001 decreased, causing the surface reflectivity to decrease to below 13%.

[0134] It is evident that when the alkali concentration is low, for example, when the sodium hydroxide content in the second solution is less than 6L, the surface reflectivity decreases rapidly, resulting in a faster change in surface morphology and making it difficult to control. When the alkali concentration is high, for example, when the sodium hydroxide content in the second solution is greater than 10L, the area ratio of the polished surface 1201 in the entire first surface 1001 decreases, and the surface reflectivity also decreases. In comparison, considering the stability and repeatability of mass production, controlling the sodium hydroxide content in the second solution between 6L and 10L is beneficial for the stable and controllable formation of the first surface 1001 with composite surface morphology requirements and high reflectivity.

[0135] In some cases, during the step of treating the initial polished surface 118 with the second solution, there is a certain degree of randomness in the formation of the pyramid structure. The speed or time at which the pyramid structure is formed in different areas may be different. Based on this, a second pyramid structure 104 can also be formed around the first pyramid structure 101. The base size of the second pyramid structure 104 can be smaller than the base size of the first pyramid structure 101. Along the first direction X, the height of the second pyramid structure 104 can be smaller than the height of the first pyramid structure 101.

[0136] In some cases, refer to Figure 14 The reflectivity of the initial polished surface 118 can be 35%~40%, for example, it can be 35%, 35.5%, 36%, 36.5%, 37%, 37.5%, 38%, 38.5%, 39%, 39.5% or 40%, etc.

[0137] In some cases, refer to Figure 14 The initial polished surface 118 includes an initial tower base structure 128. The size of the initial tower base structure 128 can be 10μm to 15μm, for example, it can be 10μm, 11μm, 11.5μm, 12μm, 12.5μm, 13μm, 13.5μm, 14μm, 14.5μm or 15μm, etc.

[0138] It is worth noting that the size of the initial pyramid base structure 128 in the initial polished surface 118 directly affects the reflectivity of the initial polished surface 118. When the size of the initial pyramid base structure 128 is in the range of 10μm to 15μm, the reflectivity of the initial polished surface 118 will be approximately in the range of 35% to 40%. Moreover, designing the reflectivity of the initial polished surface 118 to be 35% to 40%, or designing the size of the initial pyramid base structure 128 to be 10μm to 15μm, is beneficial for the stable formation of the first pyramid structure 101 based on the initial polished surface 118.

[0139] It is worth noting that increasing the size of the initial tower base structure 128 will increase the reflectivity of the initial polished surface 118. Referring to Table 2, the following will explain in detail the influence of the surface morphology of the initial polished surface 118 on the surface morphology of the final first surface 1001 by designing the reflectivity of the initial polished surface 118.

[0140] Table 2: Effect of the reflectivity of the initial polished surface on the reflectivity of the first surface

[0141] As can be seen from experimental groups SP5 and SP7 in Table 2, when the reflectivity of the initial polished surface is low, for example, 20%~25%, the morphology of the first surface formed based on this initial polished surface is uncontrollable during the step of treating the initial polished surface with the second solution. This leads to significant fluctuations in the reflectivity of the first surface, which is detrimental to the stability of mass production and to achieving repeatability. Therefore, the reflectivity of the initial polished surface 118 is designed to be 35%~40%, which is beneficial for the stable formation of the first pyramid structure 101 based on the initial polished surface 118 (see reference). Figure 12 ), to form a first surface 1001 with stable and controllable surface morphology (reference) Figure 12 This ensures that the emissivity of the first surface 1001 is in the range of 20% to 25%.

[0142] It should be noted that the initial base structure 128 can be regarded as the base part of the complete pyramid structure. The dimensions of the initial base structure 128 include either the side length or the diagonal of the orthographic projection pattern of its bottom onto the initial base 108. For example, if the orthographic projection pattern of the bottom of the initial base structure 128 onto the initial base 108 is a regular quadrilateral, the base dimensions of the initial base structure 128 are either the side length or the diagonal length of the regular quadrilateral.

[0143] Furthermore, the base dimensions of the various pyramid structures mentioned in the foregoing embodiments may also include either the side length or the diagonal of the orthographic projection pattern of its base onto the base 100.

[0144] In practical applications, the bottom of either the pyramid structure or the base structure is considered the base. The orthographic projection of the base onto the base can also be an irregular polygon. In this case, the side length or diagonal length of the orthographic projection of the base onto the base is not absolute, but rather artificially defined to characterize the size of the pyramid base or the base structure. For example, if the orthographic projection of the base onto the base is an irregular quadrilateral, the length of the base can be defined as the length of the longest side of the irregular quadrilateral, the width of the base can be defined as the length of the shortest side of the irregular quadrilateral, and the diagonal length of the base can be defined as the length of the longest diagonal of the irregular quadrilateral. It should be understood that the above is only an illustrative example, and in practice, it can be flexibly defined according to actual needs. In addition, the orthographic projection pattern of the base on the foundation can be an irregular quadrilateral, or other irregular polygons, circles, or irregular shapes that are approximately circular. In this case, the size of the base of the pyramid structure or the size of the base structure is to select multiple regions of different specific areas in the base. These specific areas can be flexibly defined according to actual needs, and then the average value of the side length, diagonal, or diameter of multiple regions of different specific areas is calculated.

[0145] In some cases, in conjunction with references Figures 12 to 14 The polished surface 1201 of the second zone 120 is formed on the basis of the initial polished surface 118. The emissivity of the polished surface 1201 is almost the same as that of the initial polished surface 118. The size of the tower base structure in the polished surface 1201 is also almost the same as that of the initial tower base structure 128 in the initial polished surface 118.

[0146] The following details the steps involving the use of the first solution and the steps involving the use of the second solution, along with other process parameters.

[0147] In some cases, the process temperature of the first solution can be lower than that of the second solution. In this way, increasing the process temperature can help to increase the alkali content in the second solution, thereby promoting the formation of the first pyramid structure 101.

[0148] In some examples, the process temperature of the first solution can be 50℃~70℃, for example, it can be 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃ or 70℃, etc.; the process temperature of the second solution can be 60℃~80℃, for example, it can be 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃ or 80℃, etc.

[0149] In some cases, the processing time for the first solution can be shorter than the processing time for the second solution.

[0150] In some examples, the processing time of the first solution can be 100s to 200s, for example, 100s, 110s, 120s, 130s, 140s, 150s, 160s, 170s, 180s, 190s, or 200s; the processing time of the second solution can be 150s to 260s, for example, 150s, 160s, 170s, 180s, 190s, 200s, 210s, 220s, 230s, 240s, 250s, or 260s.

[0151] In some cases, before using the first solution, the method for manufacturing photovoltaic cells may also include: combining with reference to... Figure 13 and Figure 15 At least a third solution is used to treat the initial first surface 1081, transforming the initial first surface 1081 into an initial first textured surface 138 including a fifth pyramid structure 1381; in conjunction with reference Figure 15 and Figure 14 In the step of using the first solution, at least the top of the fifth pyramid structure 1381 is removed, so that the initial first velvet surface 138 is transformed into the initial polished surface 118.

[0152] in, Figure 15 This is a partial cross-sectional schematic diagram of a photovoltaic cell manufacturing method provided in another embodiment of the present disclosure, after the initial substrate has been treated with a third solution.

[0153] It should be noted that in the step of using the first solution, almost all the tops of the fifth pyramid structure 1381 are removed, resulting in no residue of the fifth pyramid structure 1381 in the initial polished surface 118, or in other words, making the initial polished surface 118 as completely polished as possible. For example, the size of the initial pyramid base structure 128 in the initial polished surface 118 is 10μm~15μm.

[0154] In some examples, the initial substrate 108 can be a single-crystal silicon wafer doped with N-type dopant before the third solution is applied. In one example, the thickness of the initial substrate 108 in the first direction X can be 90 μm to 120 μm, for example, it can be 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm or 120 μm, etc.

[0155] In some examples, before using the third solution, the manufacturing method of the photovoltaic cell may further include: a first wet cleaning process, mainly used to remove surface dirt, surface damage, or metallic impurities from the initial substrate 108; after using the third solution, the manufacturing method of the photovoltaic cell may further include: performing a first wet acid washing process on the initial first textured surface 138 to dilute the residual third solution and the surface oxide layer generated during the production process, thereby achieving the purpose of cleaning the initial first textured surface 138; and then drying the initial first textured surface 138 that has undergone the first wet acid washing process. It should be noted that the first wet cleaning process, the use of the third solution, the first wet acid washing process, and drying can all be sub-steps of the first texturing treatment of the initial substrate 108.

[0156] The third and second solutions will be described in detail below.

[0157] In some examples, the third solution may be an alkaline solution, with an alkaline concentration lower than that of the second solution.

[0158] In one example, the alkali in the third solution can be sodium hydroxide, the total volume of the third solution is 380L, and the content of sodium hydroxide in the third solution can be 1L to 3L, for example, 1L, 1.1L, 1.2L, 1.3L, 1.4L, 1.5L, 1.6L, 1.7L, 1.8L, 1.9L, 2L, 2.1L, 2.2L, 2.3L, 2.4L, 2.5L, 2.6L, 2.7L, 2.8L, 2.9L, or 3L, etc.

[0159] In one example, the third solution contains a second texturing additive, and the total volume of the third solution is 380L. The content of the second texturing additive in the third solution can be 0.5L to 1L, for example, 0.5L, 0.55L, 0.6L, 0.65L, 0.7L, 0.75L, 0.8L, 0.85L, 0.9L, 0.95L, or 1L, etc.

[0160] In one example, the process temperature of the third solution can be 70℃~80℃, for example, it can be 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃ or 80℃, etc.

[0161] In one example, the processing time for the third solution can be 200s to 500s, for example, 200s, 210s, 220s, 230s, 240s, 250s, 260s, 270s, 280s, 290s, 300s, 310s, 320s, 330s, 340s, 350s, 360s, 370s, 380s, 390s, 400s, 410s, 420s, 430s, 440s, 450s, 460s, 470s, 480s, 490s, or 500s, etc.

[0162] In some examples, the reference continues. Figure 13 and Figure 15 The initial second surface 1082 can also be treated with a third solution to transform it into an initial second textured surface 148. After using the third solution and before using the first solution, the photovoltaic cell manufacturing method may further include: (Refer to...) Figure 16 The process involves doping to form at least a first diffusion layer 109 and a first getter layer 119 on the initial first textured surface 138, and a second diffusion layer 129 and a second getter layer 139 on the initial second textured surface 148; in conjunction with reference to... Figure 16 and Figure 17 Remove the first getter layer 119; refer to the reference Figure 17 and 14 In the step of using the first solution, the initial second textured surface 148 is protected by the second getter layer 139 as a mask; in conjunction with the reference Figure 17 and Figure 18 After the first solution is applied, the second getter layer 139 is removed.

[0163] in, Figure 16 A partial cross-sectional schematic diagram of a photovoltaic cell manufacturing method according to another embodiment of this disclosure after doping treatment; Figure 17 This is a partial cross-sectional view of a photovoltaic cell manufacturing method provided in another embodiment of the present disclosure after removing the first getter layer; Figure 18 This is a partial cross-sectional view of a photovoltaic cell manufacturing method according to another embodiment of the present disclosure, after the removal of the second getter layer. It should be noted that this view is intended to illustrate the surface morphology of the formed first surface 1001 and second surface 1002. Figure 18 The first and second diffusion layers are not shown in the diagram.

[0164] It is worth noting that, under high temperature conditions, an electric field or recombination center of a certain intensity can be formed by the first getter layer 119 and the second getter layer 139, attracting and capturing impurities inside the initial substrate 108, thereby improving the internal electrical properties of the initial substrate 108. The first getter layer 119 and the second getter layer 139 can then be removed using existing process equipment.

[0165] Furthermore, in the step of using the first solution, the second getter layer 139 can also be used as a mask to prevent the initial second textured surface 148 from being polished, so that in the subsequent step of using the second solution, a second surface 1002 with the required surface morphology can be formed based on the initial second textured surface 148.

[0166] In some examples, in the initial second nap 148 (reference) Figure 17 Based on this, a second solution is used to polish the initial polished surface 118 (reference). Figure 14 In the processing steps, refer to Figure 18 Alternatively, a second solution can be used to treat the initial second textured surface 148 (reference). Figure 17 The process is carried out to form a second surface 1002 that includes at least a third pyramid structure 105.

[0167] In one example, referring to the reference Figure 17 , Figure 14 and Figure 4 In the step of treating the initial second textured surface 148 with the second solution, the surface morphology of the second surface 1002 includes not only the third pyramid structure 105 but also a protruding structure 106. The protruding structure 106 is located on the side and / or side edge of the third pyramid structure 105 and along the first direction X. The height of the protruding structure 106 is less than the height of the third pyramid structure 105. The design of the alkali concentration of the second solution being higher than that of the third solution not only facilitates the formation of the third pyramid structure 105 with a larger base size but also promotes the formation of the protruding structure 106.

[0168] In some cases, a chain cleaning machine can be used to remove the first getter layer 119 under the action of hydrofluoric acid (see reference). Figure 16 ), and at this time the second getter layer 139 (reference) Figure 16The water film on the surface protects the second getter layer from removal; subsequently, after using the first solution, the second getter layer 139 can be removed using a hydrofluoric acid bath (see reference). Figure 17 ).

[0169] In some examples, refer to Figure 13 The initial substrate 108 also has an initial side surface 1083 connecting the initial first surface 1081 and the initial second surface 1082; during the doping process, a first getter layer (not shown) and / or a second getter layer (not shown) are also formed on at least a portion of the initial side surface 1083; in conjunction with reference to Figure 16 and Figure 17 In the subsequent step of removing the first getter layer 119 located on the initial first velvet surface 138, the first getter layer and / or the second getter layer located on the initial side surface 1083 are also removed simultaneously.

[0170] In some cases, refer to Figure 13 The initial substrate 108 also has an initial side surface 1083 connecting the initial first surface 1081 and the initial second surface 1082; Reference Figure 14 In the step of using the first solution, the initial side surface 1083 is also treated with the first solution; in conjunction with the reference Figure 14 and Figure 6 In the step of using the second solution, the second solution is also used on the initial side 1083 (reference). Figure 13 The surface is processed to form a side surface 1003 including multiple third regions 130 and multiple fourth regions 140. The surface morphology of the third region 130 may include a fourth pyramid structure 107, and the surface morphology of the fourth region 140 is a polished surface 1201. The base size of the fourth pyramid structure 107 is smaller than the base size of the first pyramid structure 101, and the height of the fourth pyramid structure 107 is smaller than the height of the first pyramid structure 101 along the first direction X.

[0171] In other words, in the step of using the first solution, the initial side surface 1083 and the initial second surface 1082 are polished together; in the step of using the second solution, the initial side surface 1083 and the initial second surface 1082 are texturing together, so that the final side surface 1003 has a similar morphology to the first surface 1001. However, generally speaking, the size of the fourth pyramid structure 107 included in the side surface 1003 is smaller than the size of the first pyramid structure 101 included in the first surface 1001, and the area occupied by the fourth region 140 in the side surface 1003 is different from the area occupied by the second region 120 in the first surface 1001.

[0172] In some cases, when providing an initial substrate 108 (reference) Figure 13After that, the initial first surface 1081 (reference) was treated with the first solution. Figure 13 Before and after processing, the photovoltaic cell manufacturing method may further include the following steps: before using the first solution, after removing the first getter layer 119 (refer to...) Figure 16 After that, a pre-cleaning process is performed to perform basic cleaning on the initial substrate 108; after using the first solution, a mask cleaning process is used to remove the second getter layer 139 (see reference). Figure 17 Then, the hydrochloric acid cleaning process, slow lifting process, and drying process are carried out in sequence. The hydrochloric acid cleaning process is mainly used to remove residual additives. The slow lifting process is used to slowly, uniformly, and vertically lift the initial substrate 108 that has undergone the hydrochloric acid cleaning process out of the water tank to clean the residual cleaning liquid on its surface and improve its surface hydrophobicity, thereby minimizing the risk of water stains or trace impurities remaining on the surface of the initial substrate 108 that has undergone the hydrochloric acid cleaning process, so as to achieve the purpose of cleaning its surface.

[0173] It should be noted that the pre-cleaning process, the use of the first solution, the mask cleaning process, the hydrochloric acid cleaning process, the slow lifting process, and the drying process can all be considered as sub-processes for polishing the initial substrate 108.

[0174] In some cases, during the formation of the initial polished surface 118 (reference) Figure 14 Following the initial polishing of the surface 118 with the second solution, the photovoltaic cell manufacturing method may further include the following steps: Before using the second solution, a second wet cleaning process is performed, mainly to simply remove surface dirt, surface damage, or metallic impurities from the initial polished surface 118; after using the second solution, a water washing process, an ozone cleaning process, a second wet acid washing process, a slow lifting process, and drying are performed sequentially. The water washing process is interspersed between the use of the second solution and the texturing and second wet acid washing processes to act as a separator, preventing cross-contamination between the cleaning solutions used in the second solution and the second wet acid washing process; the ozone cleaning process mainly serves to round the pyramid structure, so that the tops of the various pyramid structures on the surface of the final substrate 100 are curved surfaces.

[0175] In some embodiments, reference Figure 8Taking a photovoltaic cell, specifically an HJT cell, as an example, forming the passivation contact structure 102 may include the following steps: growing amorphous silicon on the first surface 1001 and the second surface 1002 using a PECVD (Plasma Enhanced Chemical Vapor Deposition) process to form a first dielectric layer 1121 and a second dielectric layer 1122, and growing a doped microcrystalline silicon thin film to form a first doped layer 1221 and a second doped layer 1222. Further, a transparent conductive film 133 is prepared using APCVD (Atmospheric Pressure CVD). Forming the electrode 103 may include the following steps: forming a first electrode 113 and a second electrode 123 using a screen printing process and a metallization process, wherein the metallization process can complete the low-temperature curing of the electrode paste at approximately 200°C and ultimately form an ohmic contact between the first electrode 113, the second electrode 123, and the transparent conductive film 133.

[0176] The following table 3 details the tensile force exhibited by the electrode in the photovoltaic cell by describing the morphology of the surface that matches the electrode.

[0177] Table 3: Influence of different surface morphologies matched with the electrode on the tensile force exhibited by the electrode in the photovoltaic cell

[0178] It should be noted that SP1 to SP4 in Table 3 correspond to SP1 to SP4 in Table 1. That is, the surfaces that match the electrodes and are associated with SP1 to SP4 in Table 3 are all initially polished using the second solution on surface 118 (reference). Figure 14 The sodium hydroxide content in the second solution differs at least in SP1 to SP4 after processing. Based on this, it can be seen that, compared to the fully polished back side in control group 2, the reference... Figures 1 to 18 The first surface 1001 formed by the photovoltaic cell manufacturing method provided in another embodiment of the present disclosure can improve the firmness of the electrode 103 in the photovoltaic cell. Specifically, the electrode 103 exhibits greater tensile strength in the photovoltaic cell, and the PAD qualification rate is higher than 95%, which is much higher than the 67% corresponding to the control group 2. Moreover, the gain of the first surface 1001 formed by the photovoltaic cell manufacturing method provided in another embodiment of the present disclosure on the firmness of the electrode 103 can match the conventional textured surface in the control group 1, and the reflectivity of the first surface 1001 is lower than that of the conventional textured surface, which is more conducive to improving the short-circuit current of the photovoltaic cell and improving the passivation effect of the passivation contact structure 102.

[0179] The following table 4 details the impact of different morphologies of the first surface on the performance parameters of photovoltaic cells.

[0180] Table 4: Influence of different surface morphologies of the first surface on the performance parameters of photovoltaic cells

[0181] As can be seen, reference Figures 1 to 18 Compared to Comparative Example 1 in Table 4, in another embodiment of this disclosure, namely Example 1 in Table 4, the polished surface 1201 of the first surface 1001 is smoother than the textured surface, reducing the risk of performance degradation due to surface defects. The polished surface 1201 greatly enhances the ability of the first surface 1001 to reflect light, resulting in more reflection of long-wavelength light after it reaches the first surface 1001. The reflecting substrate 100 further absorbs and utilizes the light, thereby increasing the short-circuit current Isc by 15mA to 30mA. In addition, the specific surface area of ​​the polished surface 1201 is significantly reduced, the recombination rate of the first surface 1001 decreases, and the passivation effect is improved. Combined with the passivation contact structure 102, which has a better passivation effect, the series resistance Rs of the photovoltaic cell is also significantly reduced by about 0.4mΩ. Therefore, through the combination of these factors, the photoelectric conversion efficiency of the photovoltaic cell can be improved by at least 0.10%.

[0182] However, in conjunction with control groups 2 and SP1 to SP4 in Table 3, and comparative examples 2 and Example 1 in Table 4, another embodiment of this disclosure, namely Example 1 in Table 4, shows that the photovoltaic cell has a photoelectric conversion efficiency Eff that is basically the same as that of comparative example 2. However, while taking into account the gain in photoelectric conversion efficiency, the electrode 103 corresponding to Example 1 exhibits greater pulling force in the photovoltaic cell and can be more firmly set in the photovoltaic cell.

[0183] Another embodiment of this disclosure provides a photovoltaic module, which will be described in detail below with reference to the accompanying drawings. It should be noted that parts that are the same as or corresponding to those in the foregoing embodiments will not be repeated here.

[0184] Reference Figures 1 to 10 ,as well as Figure 19 and Figure 20 The photovoltaic module includes: a battery string, which is formed by connecting multiple photovoltaic cells 40 provided in the foregoing embodiments, or by connecting photovoltaic cells 40 formed by the manufacturing method of multiple photovoltaic cells provided in the foregoing embodiments; an encapsulating film 41 for covering the surface of the battery string; and a cover plate 42 for covering the surface of the encapsulating film 41 facing away from the battery string.

[0185] in, Figure 19 A partial three-dimensional schematic diagram of a cell string in a photovoltaic module provided in yet another embodiment of this disclosure; Figure 20 This is a partial cross-sectional schematic diagram of a photovoltaic module provided in yet another embodiment of the present disclosure.

[0186] In some embodiments, the photovoltaic cell 40 includes, but is not limited to, one or any combination of PERC cells, BC cells, TOPCon cells, HIT / HJT cells, thin-film solar cells, and tandem cells. Among them, BC cells include, but are not limited to, IBC cells (Interdigitated Back Contact), HBC cells (Heterojunction Back Contact), TBC cells (TOPCon Back Contact), or HTBC cells (Hybrid Passivated Back Contact).

[0187] It should be noted that multiple photovoltaic cells 40 can be electrically connected to each other via solder strips 43. Figure 19 and Figure 20 Taking a photovoltaic cell 40 as an example, which is a cell with electrodes on both sides, and illustrating only one positional relationship between photovoltaic cells 40, that is, the electrodes of the photovoltaic cells 40 with the same polarity are arranged in the same direction, or in other words, the electrodes of each photovoltaic cell 40 with positive polarity are arranged facing the same side, so that the solder ribbon 43 connects the different sides of two adjacent photovoltaic cells 40 respectively. In other embodiments, the photovoltaic cells can also be arranged with electrodes of different polarities facing the same side, that is, the electrodes of multiple adjacent photovoltaic cells are arranged in the order of first polarity, second polarity, and first polarity respectively, then the solder ribbon connects the same side of two adjacent photovoltaic cells.

[0188] In some embodiments, the photovoltaic cells 40 are electrically connected in the form of a single cell or multiple segments to form multiple cell strings, and the multiple cell strings are electrically connected in series and / or parallel. The photovoltaic cells 40 can be a single cell or a sliced ​​cell, where a sliced ​​cell refers to a cell formed by cutting a complete single cell.

[0189] In some embodiments, the encapsulating film 41 includes a first encapsulating layer and a second encapsulating layer. The first encapsulating layer covers one of the front or back sides of the photovoltaic cell 40, and the second encapsulating layer covers the other of the front or back sides of the photovoltaic cell 40. Specifically, at least one of the first or second encapsulating layer can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene elastomer (POE) film, or polyethylene terephthalate (PET) film. Alternatively, at least one of the first or second encapsulating layer can also be an EP film, an EPE film, or a PVP film. Here, EP film refers to a co-extruded film composed of stacked EVA film and POE film; EPE film refers to a co-extruded film formed by sequentially stacking EVA film + POE film + EVA film; and PVP film refers to a co-extruded film formed by stacking POE film + EVA film + POE film. Co-extruded films can be prepared by sequentially extruding one or more raw materials onto another pre-made film during the film processing, or by bonding different types of pre-made films together.

[0190] In some cases, the first encapsulation layer and the second encapsulation layer still have a boundary line before lamination. After lamination, the photovoltaic module will no longer have the concept of a first encapsulation layer and a second encapsulation layer. That is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 41.

[0191] In some embodiments, the cover plate 42 can be a glass cover plate, a plastic cover plate, or other cover plate with light-transmitting function. Specifically, the surface of the cover plate 42 facing the encapsulating film 41 can be an uneven surface or a textured surface containing multiple raised structures, thereby increasing the utilization rate of incident light. The cover plate 42 includes a first cover plate and a second cover plate, the first cover plate being opposite to the first encapsulation layer, and the second cover plate being opposite to the second encapsulation layer.

[0192] Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the embodiments of this disclosure. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the embodiments of this disclosure; therefore, the scope of protection of the embodiments of this disclosure should be determined by the scope defined in the claims.

Claims

1. A photovoltaic cell, characterized in that, include: The substrate has a first surface and a second surface opposite each other along a first direction, the first direction being the thickness direction of the substrate; The first surface includes multiple first regions and multiple second regions. The surface morphology of the first region includes a first pyramid structure, and at least a portion of the surface morphology of the first region also includes a second pyramid structure. The surface morphology of the second region is a polished surface. The base size of the second pyramid structure is smaller than the base size of the first pyramid structure, and the height of the second pyramid structure is smaller than the height of the first pyramid structure along the first direction. A passivated contact structure is located on the first surface and / or the second surface. On the side of the passivated contact structure away from the substrate, the surface morphology of the region opposite the first region includes the first pyramid structure, and the surface morphology of the region opposite the second region is the polished surface. An electrode is located on the side of the passivated contact structure away from the substrate, and a single electrode is located on at least one first region and at least one second region, with at least one entire first region and / or at least one entire second region between adjacent two electrodes.

2. The photovoltaic cell according to claim 1, characterized in that, The base size of the first pyramid structure is 0.5μm to 1.3μm, and the height of the first pyramid structure is 0.5μm to 0.7μm; the base size and the height of the second pyramid structure are both less than 0.3μm.

3. The photovoltaic cell according to claim 1, characterized in that, The ratio of the area of ​​the region with the second pyramid structure in the first surface to the area of ​​the entire first surface is 4% to 6%.

4. The photovoltaic cell according to claim 1, characterized in that, The surface morphology of the second surface includes a third pyramid structure, the base size of which is larger than the base size of the first pyramid structure.

5. The photovoltaic cell according to claim 4, characterized in that, The base dimensions of the third pyramid structure are 2.5μm to 3.5μm.

6. The photovoltaic cell according to claim 4, characterized in that, The surface morphology of the second surface also includes a protruding structure, which is located on the side and / or side edge of the third pyramid structure, and along the first direction, the height of the protruding structure is less than the height of the third pyramid structure.

7. The photovoltaic cell according to claim 1, characterized in that, The ratio of the base dimension of the first pyramid structure to the height of the first pyramid structure is 1.5 to 2.

8. The photovoltaic cell according to claim 1, characterized in that, The ratio of the area of ​​the region with the first pyramid structure in the first surface to the area of ​​the entire first surface is 35% to 50%.

9. The photovoltaic cell according to claim 1, characterized in that, The substrate also has a side surface connecting the first surface and the second surface; The side includes multiple third zones and multiple fourth zones. The surface morphology of the third zone includes a fourth pyramid structure, and the surface morphology of the fourth zone is the polished surface. The base size of the fourth pyramid structure is smaller than that of the first pyramid structure, and the height of the fourth pyramid structure is smaller than that of the first pyramid structure along the first direction.

10. The photovoltaic cell according to claim 9, characterized in that, The base size of the fourth pyramid structure is 0.5μm~1μm, and the height of the fourth pyramid structure is 0.3μm~0.6μm.

11. The photovoltaic cell according to claim 9, characterized in that, The ratio of the area of ​​the region with the fourth pyramid structure on the side to the area of ​​the entire side is 20% to 40%.

12. The photovoltaic cell according to claim 1, characterized in that, The reflectivity of the first surface is 20%~25%.

13. The photovoltaic cell according to claim 1, characterized in that, The top of the first pyramid structure is curved.

14. The photovoltaic cell according to claim 1, characterized in that, The passivated contact structure includes: a dielectric layer located on the first surface and / or the second surface; and a doped layer located on the side of the dielectric layer away from the substrate. The electrode is a first electrode, and the photovoltaic cell further includes a second electrode located on the second surface.

15. The photovoltaic cell according to claim 1, characterized in that, The first surface includes a fifth region and a sixth region that are alternately arranged along the second direction; The passivated contact structure includes a first passivated contact structure located in the fifth region and a second passivated contact structure located in the sixth region; The electrode includes a first electrode located on the side of the first passivated contact structure away from the substrate, and a second electrode located on the side of the second passivated contact structure away from the substrate.

16. A method for manufacturing a photovoltaic cell, characterized in that, include: A substrate is formed having a first surface and a second surface opposite each other along a first direction, the first direction being the thickness direction of the substrate; the first surface includes a plurality of first regions and a plurality of second regions, the surface morphology of the first region includes a first pyramid structure, and at least a portion of the surface morphology of the first region also includes a second pyramid structure, the surface morphology of the second region being a polished surface; wherein, the base size of the second pyramid structure is smaller than the base size of the first pyramid structure, and along the first direction, the height of the second pyramid structure is smaller than the height of the first pyramid structure; A passivated contact structure is formed on the first surface and / or the second surface. On the side of the passivated contact structure away from the substrate, the surface morphology of the region opposite to the first region includes the first pyramid structure, and the surface morphology of the region opposite to the second region is the polished surface. An electrode is formed on the side of the passivated contact structure away from the substrate, and a single electrode is located on at least one first region and at least one second region, and adjacent two electrodes are spaced apart by at least one entire first region and / or by at least one entire second region.

17. The method for manufacturing a photovoltaic cell according to claim 16, characterized in that, The steps for forming the substrate include: An initial substrate is provided, the initial substrate having an initial first surface and an initial second surface opposite to each other in a first direction; The initial first surface is treated with a first solution to transform the initial first surface into an initial polished surface; The initial polished surface is treated with a second solution to transform a portion of the initial polished surface into a first region with a surface morphology including the first pyramid structure, and to transform other regions of the initial polished surface into a second region with a surface morphology of the polished surface. Both the first solution and the second solution are alkaline solutions, and the alkaline concentration of the first solution is less than that of the second solution.

18. The method for manufacturing a photovoltaic cell according to claim 17, characterized in that, The reflectivity of the initial polished surface is 35%~40%; and / or, the initial polished surface includes an initial tower base structure, the size of which is 10μm~15μm.

19. The method for manufacturing a photovoltaic cell according to claim 17, characterized in that, The process temperature of the first solution is lower than that of the second solution; and / or, the processing time of the first solution is shorter than that of the second solution.

20. The method for manufacturing a photovoltaic cell according to claim 17, characterized in that, Before using the first solution, the method for manufacturing the photovoltaic cell further includes: treating the initial first surface with at least a third solution to transform the initial first surface into an initial first textured surface including a fifth pyramid structure; In the step of using the first solution, at least the top of the fifth pyramid structure is removed, so that the initial first velvet surface is transformed into the initial polished surface.

21. The method for manufacturing a photovoltaic cell according to claim 20, characterized in that, The third solution is an alkaline solution, and the alkaline concentration of the third solution is less than that of the second solution.

22. The method for manufacturing a photovoltaic cell according to claim 20, characterized in that, The initial second surface is further treated with the third solution to transform it into an initial second textured surface. After using the third solution and before using the first solution, the method for manufacturing the photovoltaic cell further includes: performing a doping process to form at least a first diffusion layer and a first getter layer on the initial first textured surface, and forming a second diffusion layer and a second getter layer on the initial second textured surface; and removing the first getter layer. During the step of using the first solution, the initial second textured surface is protected by the second getter layer as a mask. After using the first solution, the second getter layer is removed.

23. The method for manufacturing a photovoltaic cell according to claim 17, characterized in that, The initial substrate also has an initial side surface connecting the initial first surface and the initial second surface; In the step of using the first solution, the initial side surface is also treated with the first solution; In the step of using the second solution, the initial side surface is also treated with the second solution to form a side surface including multiple third regions and multiple fourth regions, wherein the surface morphology of the third region includes a fourth pyramid structure, the surface morphology of the fourth region is the polished surface, the base size of the fourth pyramid structure is smaller than the base size of the first pyramid structure, and the height of the fourth pyramid structure is smaller than the height of the first pyramid structure along the first direction.

24. A photovoltaic module, characterized in that, include: A battery string is formed by connecting multiple photovoltaic cells as described in any one of claims 1 to 15, or by connecting multiple photovoltaic cells formed by the manufacturing method of photovoltaic cells as described in any one of claims 16 to 23; An encapsulating film is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

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