Back-contact solar cell and its manufacturing method, photovoltaic assembly

Abstract

Embodiments of the present application relate to the field of photovoltaic power generation and provide a back-contact solar cell, a method for manufacturing the same, and a photovoltaic power generation assembly. The back-contact solar cell includes a substrate and alternately arranged first doping regions and second doping regions, a first passivation contact layer located in the first doping region and a second passivation contact layer located in the second doping region, a doping oxide layer including a first portion located on the surface of the first passivation contact layer and a second portion located in the second doping region, and a connecting layer located in a portion of the first portion, surrounding a portion of the second portion and electrically connected to the second passivation contact layer, and located on the side surface of the first passivation contact layer and electrically connected to the first passivation contact layer. According to the back-contact solar cell provided by embodiments of the present application, at the very least, the hot spot effect can be improved and the photoelectric conversion efficiency can be improved.

Description

Technical Field

[0004] ,

[0001] The embodiments of the present application relate to the field of photovoltaic power generation, particularly to back contact solar cells and their manufacturing methods, and photovoltaic power generation assemblies.

Background Art

[0002] An IBC cell (Interdigitated Back Contact cell) is a back junction back contact solar cell structure in which positive and negative metal electrodes are arranged in an interdigitated pattern on the non-light-receiving surface of the cell, and its PN junction is located on the back of the cell. Here, back junction means that the PN junction is located on the back of the cell. The IBC cell is one of the solar cells with the highest current conversion efficiency at present. This cell uses single crystal silicon as the substrate, and both the PN junction and the metal electrodes are located on the back of the cell, and there is no metal electrode blocking light on the front, so a very high short-circuit current and conversion efficiency can be obtained.

[0003] A photovoltaic power generation assembly composed of multiple cells is usually installed in a wide and sunny place. During long-term use, it is inevitable that shielding objects such as birds, dust, and fallen leaves will fall. These shielding objects form shadows on the solar cell assembly, and in an array of large solar cell assemblies, inappropriate row spacing may also form shadows on each other. The existence of local shadows causes changes in the current and voltage of some cell sheets in the solar cell assembly. As a result, the product of the local current and voltage of the solar cell assembly increases, causing a local temperature rise in these cell assemblies. Defects in some cell sheets of the photovoltaic power generation assembly itself may also cause local heating of the assembly during operation, and this phenomenon is called the "hot spot effect".

[0004] In IBC cells, both the P-type and N-type doping regions are located on the back of the substrate and completely isolated. Therefore, during the process of forming cell strings with multiple IBC cells and then packaging them into a photovoltaic assembly, the hot spot effect can affect the power of the photovoltaic assembly and potentially cause safety problems due to localized temperature increases. Thus, how to improve and resolve the "hot spot effect" is an urgent issue that engineers must address today. [Overview of the project] [Problems that the invention aims to solve]

[0005] The embodiments of this application provide a back-contact solar cell, a method for manufacturing the same, and a photovoltaic assembly that are advantageous in improving the hot spot effect of the back-contact solar cell and improving the photoelectric conversion efficiency. [Means for solving the problem]

[0006] According to some embodiments of the present application, one embodiment of the present application provides a back-contact solar cell having a first surface and a second surface facing each other, the first surface comprising a substrate having alternately arranged first doping regions and second doping regions, a first passivation contact layer located in the first doping region, a doping oxide layer comprising a first portion located on the surface of the first passivation contact layer and a second portion extending along the edge of the first portion toward the direction of the second doping region so as to be located in the second doping region, a second passivation contact layer located in the second doping region and having a doping type different from that of the first passivation contact layer, and a connecting layer located in a portion of the first portion, surrounding a portion of the second portion and electrically connected to the second passivation contact layer, and located on the side surface of the first passivation contact layer and electrically connected to the first passivation contact layer.

[0007] In some embodiments, the length range of the second portion in the first direction is 0 to 3 μm, and the first direction is the direction from the second doping region toward the first doping region.

[0008] In some embodiments, the first distance between the first doping region and the second surface is greater than the second distance between the second doping region and the second surface, the second doping region has a groove relative to the first doping region, the second portion is located in the groove, the connecting layer is located on the inner side surface of the groove, and the second passivation contact layer is located on the bottom surface of the groove.

[0009] In some embodiments, the difference between the first distance and the second distance is 5 μm or less.

[0010] In some embodiments, the first passivation contact layer is doped with a P-type doping element, and the first passivation contact layer comprises a continuous third and fourth portion, the third portion being located in the groove opposite the first portion and the fourth portion opposite the second portion, the second portion being located on the surface of the fourth portion, and the connecting layer being located on the side of the fourth portion and the bottom surface of the fourth portion away from the second portion.

[0011] In some embodiments, the side surface of the fourth portion has an inwardly recessed recess, and the connecting layer is located inside the recess.

[0012] In some embodiments, the angle between the bottom surface of the groove and the side surface of the groove is in the range of 110° to 150°.

[0013] In some embodiments, the doping oxide layer material includes borosilicate glass, phosphatesilicic acid glass, borosilicate glass, or phthalic acid glass.

[0014] In some embodiments, the thickness of the connecting layer is less than or equal to the thickness of the second passivation contact layer.

[0015] In some embodiments, the connecting layer includes a first connecting layer located in a portion of the first portion, and a second connecting layer surrounding a portion of the second portion and electrically connected to the second passivation contact layer, the second connecting layer having a thickness less than or equal to the thickness of the first connecting layer.

[0016] In some embodiments, the region of the second connection layer connected to the second passivation contact layer is the first connection region, and the remaining portion of the second connection layer is a second connection region whose thickness is greater than that of the first connection region.

[0017] According to some embodiments of the present application, another aspect of the embodiment of the present application provides a method for manufacturing a back-contact solar cell, the method of manufacturing a back-contact solar cell comprising the steps of: providing a substrate having a first surface and a second surface arranged facing each other, wherein the first surface has alternating doping regions and a second doping region; forming a first passivation contact layer located in the first doping region; forming a doping oxide layer including a first portion located on the surface of the first passivation contact layer and a second portion extending along the edge of the first portion toward the direction of the second doping region so as to be located in the second doping region; forming a second passivation contact layer located in the second doping region and having a different doping type than the first passivation contact layer; and forming a connection layer located in a portion of the first portion, surrounding a portion of the second portion and electrically connected to the second passivation contact layer, and located on the side of the first passivation contact layer and electrically connected to the first passivation contact layer.

[0018] In some embodiments, the steps of forming the first passivation contact layer and the doping oxide layer include: forming a first dielectric film, a first doping film, and an oxide film on the first surface of the substrate; partially removing the oxide film in the second doping region to expose the surface of the first doping film; removing the first dielectric film and the first doping film in the second doping region; and, in the process of forming the second passivation contact layer, partially removing the oxide film located in the first doping region, making the remaining oxide film a doping oxide film, and making the remaining first dielectric film together with the first doping film the first passivation contact layer.

[0019] In some embodiments, the parameters for the process of removing the first doping film from the second doping region are as follows: the etching solution is an alkaline solution, the concentration ratio of the alkaline solution is 0.1 PPM to 0.6 PPM, the etching time is 20 s to 500 s, and the etching temperature is 50°C to 90°C.

[0020] According to some embodiments of the present application, another embodiment of the present application provides a photovoltaic assembly comprising a cell string composed of a back-contact solar cell described in any one of the above embodiments, or a back-contact solar cell manufactured by a method for manufacturing a back-contact solar cell described in any one of the above embodiments; a sealing film covering the surface of the cell string; and a cover plate covering the surface of the sealing film away from the cell string.

[0021] The technical solutions provided by the embodiments of this application have at least the following advantages.

[0022] According to the back-contact solar cell provided by the embodiment of the present invention, a first doping region and a second doping region are provided on the substrate, and a first passivation contact layer and a second passivation contact layer are formed in the first doping region and the second doping region, respectively. Chemical passivation and field passivation of the first and second passivation contact layers reduce the carrier recombination rate on the substrate surface, thereby improving the photoelectric conversion efficiency of the back-contact solar cell. Next, a connecting layer is provided that is located on the doping oxide layer and electrically connected to the second passivation contact layer. The connecting layer located on the doping oxide layer is indirectly in contact with the first passivation contact layer via the doping oxide layer, and because of the dielectric film properties and low carrier mobility of the doping oxide layer itself, the leakage current path formed by the connecting layer via the doping oxide layer is limited, so the hot spot effect can be slightly improved, but the photoelectric conversion efficiency is not significantly reduced. The connecting layer is further in contact with the side surface of the first passivation contact layer. Thus, the connecting layer is in direct contact with the first passivation contact layer, and one end of the connecting layer is further in direct contact with the second passivation contact layer. This allows for the formation of a direct leakage current path, significantly improving the hot spot effect. However, because the contact area on the sides is limited and the thickness of the connecting layer located on the sides is not excessively large due to limitations in the deposition process, the leakage current path in this area is also not excessively large, and the photoelectric conversion efficiency is not excessively reduced. The hot spot effect is improved by two types of connection methods: indirect contact between the connecting layer and the first passivation contact layer, and direct contact located on the sides. This ensures the yield of the final photovoltaic assembly and the photoelectric conversion efficiency of the back contact solar cell itself.

[0023] Thirdly, a doped oxide layer is provided on some of the first passivation contact layers. By reducing the interface state charges on the surface of the first passivation contact layer, the doped oxide layer can improve the electric field distribution between the first passivation contact layer and the connection layer, and between the first passivation contact layer and the substrate, and can avoid the generation of large leakage current and other adverse effects caused by the interface state charges. Next, the doped oxide layer is located on the surface of some of the first passivation contact layers and extends to the second doping region. Thus, a concave structure is formed between the doped oxide layer, the first passivation contact layer and the substrate. The connection layer deposited on this film layer later has a thickness less than or equal to that of the second passivation contact layer due to the shielding of the doped oxide layer. This reduces the size of the leakage current path and ensures the balance between the leakage current and the cell efficiency.

Brief Description of the Drawings

[0024] One or more embodiments are exemplarily shown by images in the corresponding drawings. These exemplary descriptions do not constitute limitations on the embodiments. Unless otherwise specified, the images in the drawings do not constitute limitations on the proportions. To more clearly explain the technical solutions of the embodiments of the present application or the prior art, the drawings required for the embodiments will be briefly described below. It is obvious that the attached drawings in the following description are only some embodiments of the present application. A person skilled in the art can obtain other drawings based on these drawings without creative effort. [Figure 1] It is a plan view of a back contact solar cell provided in an embodiment of the present application. [Figure 2] It is a cross-sectional view along the A1-A2 cross-section of FIG. 1. [Figure 3] It is a partial enlarged view at B in FIG. 2. [Figure 4] It is a partial enlarged view of a back contact solar cell provided by an embodiment of the present application. [Figure 5] It is another cross-sectional view along the A1-A2 cross-section of FIG. 1. [Figure 6]It is a scanning electron microscope view of a back contact solar cell provided by one embodiment of the present application. [Figure 7] It is a partially enlarged view of a first passivation contact structure and a substrate in a back contact solar cell provided by one embodiment of the present application. [Figure 8] It is a partially enlarged view of a first doped semiconductor layer in the first passivation contact structure of FIG. 7. [Figure 9] It is a cross-sectional view of a back contact solar cell corresponding to each step in a method for manufacturing a back contact solar cell provided by another embodiment of the present application. [Figure 10] It is a cross-sectional view of a back contact solar cell corresponding to each step in a method for manufacturing a back contact solar cell provided by another embodiment of the present application. [Figure 11] It is a cross-sectional view of a back contact solar cell corresponding to each step in a method for manufacturing a back contact solar cell provided by another embodiment of the present application. [Figure 12] It is a cross-sectional view of a back contact solar cell corresponding to each step in a method for manufacturing a back contact solar cell provided by another embodiment of the present application. [Figure 13] It is a cross-sectional view of a back contact solar cell corresponding to each step in a method for manufacturing a back contact solar cell provided by another embodiment of the present application. [Figure 14] It is a cross-sectional view of a back contact solar cell corresponding to each step in a method for manufacturing a back contact solar cell provided by another embodiment of the present application. [Figure 15] It is a cross-sectional view of a photovoltaic power generation assembly provided by yet another embodiment of the present application.

Mode for Carrying Out the Invention

[0025] As can be seen from the background art, in conventional back contact solar cells, there is a hot spot effect and the photoelectric conversion efficiency is not very good.

[0026] Embodiments of the present invention provide a back-contact solar cell, a method for manufacturing the same, and a photovoltaic assembly. In the back-contact solar cell, a doping oxide layer is provided to improve the interfacial state charge between the first passivation contact layer and the connecting layer, and a doping oxide layer is provided in a second doping region to reduce the thickness of the connecting layer. The connecting layer is provided so that it is in indirect and direct contact with the first passivation contact layer, and the other end of the connecting layer is in contact with the second passivation contact layer. In this way, a leakage current path is formed and the hot spot effect is improved, thereby ensuring the yield of the final photovoltaic assembly and the photoelectric conversion efficiency of the back-contact solar cell itself.

[0027] In the description of the embodiments of this application, the technical terms "first," "second," etc., are used solely to distinguish between different subjects and should not be understood as indicating or implying relative importance, or implicitly specifying the number, specific order, or hierarchical relationship of the technical features presented. In the description of the embodiments of this application, unless otherwise clearly and specifically limited, "multiple" means two or more.

[0028] Where the “Examples” are used herein, it is understood that certain features, structures, or properties described in relation to the Examples may be included in at least one Example of the Application. The term “Examples” in each part of this Specification does not necessarily mean the same Example, nor does it mean mutually exclusive, independent, or alternative Examples. Those skilled in the art will understand, both expressly and implicitly, that the Examples described herein may be combined with other Examples.

[0029] In the description of the embodiments of this application, the term "and / or" merely describes the relationship between related objects and means that three relationships may exist. For example, in the case of A and / or B, it can represent three situations: A exists, A and B exist simultaneously, or B exists. In this specification, the symbol " / " usually indicates that the preceding and following related objects are in an "or" relationship.

[0030] In the description of the embodiments of this application, the term "multiple" means two or more (including two), similarly, "multiple sets" means two or more sets (including two sets), and "multiple sheets" means two or more sheets (including two sheets).

[0031] In the description of the embodiments of this application, the directions or positional relationships indicated by the technical terms "center," "vertical direction," "horizontal direction," "length," "width," "thickness," "top," "bottom," "front," "back," "left," "right," "up and down," "horizontal," "top," "bottom," "inside," "outside," "clockwise," "counterclockwise," "axial direction," "radial direction," and "circumferential direction" are directions or positional relationships shown based on the drawings and are used solely for the convenience and simplification of the description of the embodiments of this application. They do not imply or suggest that the devices or elements they refer to necessarily have a specific direction or must be configured or operated in a specific direction, and therefore should not be understood as limitations on the embodiments of this application.

[0032] In the description of the embodiments of this application, unless otherwise explicitly stated and limited, technical terms such as “attached,” “interconnected,” “connected,” and “fixed” should be understood in a broad sense. For example, they may be fixed connections, removable connections, or integrated connections. They may be mechanical connections or electrical connections. They may be direct connections or indirect connections via an intermediate medium, or internal communication between two elements or an interaction relationship between two elements. Those skilled in the art will be able to understand the specific meaning of the above terms in the embodiments of this application depending on the specific circumstances.

[0033] In the drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are exaggerated for better understanding and explanation. When it is described that one component (e.g., a layer, film, region, or substrate) is on or on the surface of another component, that component may be located "directly" on the surface of the other component, and a third component may exist between the two components. Conversely, when it is described that one component is formed on the surface of another component, or that another component is formed or installed on the surface of one component, it means that there is no third component between these two components. Also, when it is described that one component is formed "generally" on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on the edges of any part of the entire surface.

[0034] In the description of the embodiments of this application, when one component "includes" another component, unless otherwise stated, this does not exclude the other component, and it may further include other components. Also, when a component such as a layer, film, region, or plate is said to "be on / be located on" another component, it may be "directly" on the other component (i.e., there is no other component between the two components), or other components may be present between them. Furthermore, 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 means that there is no other component between them.

[0035] The terms used in the description of the various embodiments described herein are used solely to describe specific embodiments and are not intended to limit them. As used in the description of the various embodiments described and in the appended claims, “the parts” also includes the plural form unless expressly indicated in the context. Components include components such as layers, films, regions, or plates.

[0036] Each embodiment of the present application will be described in detail below with reference to the drawings. However, those skilled in the art will understand that many technical details are presented in each embodiment of the present application in order to help the reader better understand the present application. However, the technical proposal for which the present application seeks protection can be realized without these technical details and the various changes and modifications based on the following embodiments.

[0037] Figure 1 is a plan view of a back-contact solar cell provided according to one embodiment of the present invention. Figure 2 is a cross-sectional view along the A1-A2 section of Figure 1. Figure 3 is a partially enlarged view of section B in Figure 2.

[0038] Referring to Figures 1 to 3, according to some embodiments of the present application, one embodiment of the present application provides a back-contact solar cell, the back-contact solar cell having a first surface 101 and a second surface 102 facing each other, the first surface 101 having alternatingly arranged first doping regions 11 and second doping regions 12 on a substrate 100, a first passivation contact layer 110 located in the first doping region 11, a first portion 121 located on the surface of the first passivation contact layer 110, and along the edge of the first portion 121 so as to be located in the second doping region The doping oxidation layer 120 includes a second portion 122 extending toward the second doping region 12; a second passivation contact layer 130 located in the second doping region 12 and having a different doping type than the first passivation contact layer 110; and a connecting layer 140 located in a portion of the first portion 121, surrounding a portion of the second portion 122 and electrically connected to the second passivation contact layer 130, and located on the side of the first passivation contact layer 110 and electrically connected to the first passivation contact layer 110.

[0039] According to the back-contact solar cell provided by the embodiment of the present application, a first doping region 11 and a second doping region 12 are provided on the substrate 100, and a first passivation contact layer 110 and a second passivation contact layer 130 are formed in the first doping region 11 and the second doping region 12, respectively. Chemical passivation and field passivation of the first passivation contact layer 110 and the second passivation contact layer 130 reduce the carrier recombination rate on the substrate surface, thereby improving the photoelectric conversion efficiency of the back-contact solar cell. Next, a connecting layer 140 is provided, which is located on the doping oxide layer 120 and electrically connected to the second passivation contact layer 130. The connecting layer 140 located on the doping oxide layer 120 indirectly contacts the first passivation contact layer 110 via the doping oxide layer 120. Due to the dielectric film properties and low carrier mobility of the doping oxide layer 120 itself, the leakage current path formed by the connecting layer 140 through the doping oxide layer 120 is limited, which slightly improves the hot spot effect but does not significantly reduce the photoelectric conversion efficiency. The connecting layer 140 also contacts the side surface of the first passivation contact layer 110. Thus, the connecting layer 140 directly contacts the first passivation contact layer 110, and one end of the connecting layer 140 further directly contacts the second passivation contact layer 130. This allows for the formation of direct leakage current pathways, significantly improving the hot spot effect. However, because the contact area on the sides is limited and the thickness of the connecting layer 140 located on the sides is not excessively large due to limitations in the deposition process, the leakage current pathway in this area is also not excessively large, thus preventing an excessive reduction in photoelectric conversion efficiency. The hot spot effect is improved by two types of connection methods: indirect contact between the connecting layer 140 and the first passivation contact layer 110, and direct contact located on the sides. This ensures the yield of the final photovoltaic assembly and the photoelectric conversion efficiency of the back contact solar cell itself.

[0040] Thirdly, a doping oxide layer 120 is provided on a portion of the first passivation contact layer 110. The doping oxide layer 120 reduces the interfacial state charge on the surface of the first passivation contact layer 110, thereby improving the electric field distribution between the first passivation contact layer 110 and the connecting layer 140, and between the first passivation contact layer 110 and the substrate, thus avoiding the generation of large leakage currents and other adverse effects due to interfacial state charges. Next, the doping oxide layer 120 is located on the surface of a portion of the first passivation contact layer 110 and extends to the second doping region 12. In this way, an inwardly recessed structure is formed between the doping oxide layer 120, the first passivation contact layer 110, and the substrate, and the connecting layer 140, which is later deposited on this film layer, has a thickness that is less than or equal to the thickness of the second passivation contact layer 130 due to the shielding by the doping oxide layer 120. This reduces the size of the leakage current path and ensures a balance between leakage current and cell efficiency.

[0041] In some embodiments, the material of the substrate 100 may be an elemental semiconductor material. Specifically, the elemental semiconductor material consists of a single element and may be, for example, silicon or germanium. The elemental semiconductor material may be in a single-crystal state, a polycrystalline state, an amorphous state, or a microcrystalline state (a state having both a single-crystal state and an amorphous state simultaneously is referred to as a microcrystalline state). For example, silicon may be at least one of single-crystal silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0042] In some embodiments, the substrate 100 may be a compound semiconductor material. Typical compound semiconductor materials include, but are not limited to, materials such as silicon germanium, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, and copper indium selenium. The substrate 100 may be a sapphire substrate, a silicon substrate on an insulator, or a germanium substrate on an insulator.

[0043] In some embodiments, the substrate 100 may be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type doping element, which may be any one of the Group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate is doped with a P-type element, which may be any one of the Group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0044] In some embodiments, the first surface 101 is the back surface, and the second surface 102 is the front surface. The terms "front" and "back" in "front surface" and "back" are relative terms. That is, "front" refers to the surface facing sunlight in the vertical direction, and "back" refers to the surface away from sunlight in the vertical direction.

[0045] In some embodiments, the back-contact solar cell is a single-sided cell, where the front can be a light-receiving surface that receives incident light rays, and the back can be a non-light-receiving surface. Of these, the non-light-receiving surface can also receive incident light rays, but its efficiency in receiving incident light rays is only slightly weaker than the efficiency of the light-receiving surface.

[0046] In some embodiments, the back-contact solar cell is a double-sided cell, meaning that both the front and back surfaces of the substrate can be light-receiving surfaces capable of receiving incident light rays.

[0047] In some embodiments, the first doping region 11 refers to the region where the orthographic projection of the first electrode 104 onto the reference plane is located, and the first doping region 11 is a functional region that forms a first type of metal electrode. Similarly, the second doping region 12 refers to the region where the orthographic projection of the second electrode 105 onto the reference plane is located, and the second doping region 12 is a functional region that forms a second type of metal electrode.

[0048] In some embodiments, there is a separation region (or non-metallic electrode region) between the first doping region 11 and the second doping region 12, where the orthographic projections of the first electrode 104 and the second electrode 105 onto the reference plane do not overlap; in other words, the separation region is a functional region where no metal electrodes are formed. In some other embodiments, there is no separation region between the first doping region 11 and the second doping region 12, there is a difference in elevation between the first doping region 11 and the second doping region 12, and the film layer located in the first doping region 11 and the film layer located in the second doping region 12 do not come into contact with each other.

[0049] Furthermore, in order to ensure that the film layers in contact with the first electrode 104 and the second electrode 105 are corresponding functional film layers, the range of the first doping region 11 is set to be greater than or equal to the range of the orthographic projection of the first electrode 104 onto the reference plane. That is, any orthographic projection of the first electrode 104 onto the reference plane lies within the first doping region 11, and the distance between the edge of the first doping region 11 and the edge of the orthographic projection pattern is 0 or greater. Similarly, the range of the second doping region 12 is greater than or equal to the range of the orthographic projection of the second electrode 105 onto the reference plane. The reference plane is a single plane perpendicular to the thickness direction Z of the substrate 100. The reference plane is parallel to the plane formed by the second direction X and the first direction Y.

[0050] Furthermore, the first doping region 11, the second doping region 12, and the isolation region are regions functionally divided from the substrate 100 (or first surface 101) to explain the distribution of each film layer structure of the back-contact solar cell, and all three actually belong to the substrate 100 (or first surface 100). There are no boundary lines separating the different regions; only the film layers located in them may differ. For example, the first doping region 11 contains the first passivation contact layer 110, the second doping region 12 contains the second passivation contact layer 130, most of the isolation region contains a passivation layer, and some regions contain a connecting layer 140.

[0051] In some embodiments, the first doping region 11 is either an N region or a P region, and the second doping region 12 is the other of either an N region or a P region.

[0052] In some embodiments, the first distance between the first doping region 11 and the second surface 102 is greater than the second distance between the second doping region 12 and the second surface 102, the second doping region 12 has a groove 103 relative to the first doping region 11, the second portion 122 is located in the groove 103, the connecting layer 140 is located on the inner side surface of the groove 103, and the second passivation contact layer 130 is located on the bottom surface of the groove 103.

[0053] In some embodiments, referring to Figure 2, the difference between the first distance and the second distance is 5 μm or less, that is, the depth h of the groove 103 is 5 μm or less. Thus, the first surface 101 of the substrate 100 is a rough surface with an uneven structure, and by restricting the groove 103, the refractive index of the incident light can be increased, and the photoelectric conversion efficiency of the back-contact solar cell can be improved. Next, since the height difference between the first doping region 11 and the second doping region 12 is 5 μm or less, and the thickness of the second passivation contact layer 130 formed in the second doping region 12 is usually less than 2 μm, the function of a separation region can be realized by the height difference between the first doping region 11 and the second doping region 12 themselves, eliminating the need to provide an additional separation region, increasing the carrier collection area, and improving the photoelectric conversion efficiency of the carrier.

[0054] Furthermore, the depth h of the groove 103 is in the range of 0.5 μm to 1.5 μm. By setting the depth h of the groove 103 within this range, the etching depth of the substrate 100 can be controlled, ensuring that the first passivation contact layer 110 of the second doping region 12 is completely etched, while minimizing the etching of the substrate 100 and avoiding adverse effects from excessive etching of the substrate 100. Next, the etching time of the substrate 100 and the amount of etching solution can be reduced, thereby lowering manufacturing costs.

[0055] Specifically, the depth h of the groove 103 may be 0.5 μm, 0.8 μm, 1.2 μm, 1.5 μm, 2.3 μm, 2.6 μm, 3.1 μm, 3.8 μm, 4.2 μm, 4.5 μm, or 4.9 μm.

[0056] In some embodiments, the angle β between the bottom surface and the side surface of the groove 103 is in the range of 110° to 150°. In this way, an obtuse angle is formed between the bottom surface and the side surface of the groove 103, and the side surface of the groove 103 is inclined with respect to the bottom surface, thereby increasing the internal reflectivity of the incident light rays. The inclined surface ensures that the thickness of the connecting layer 140 located at least therein is less than or equal to the thickness of the connecting layer 140 in other areas, thereby reducing the size of the leakage current path.

[0057] The angle β between the bottom surface of the groove 103 and the side surface of the groove 103 may be 110°, 115°, 120°, 125°, 130°, 135°, 140°, 145°, or 150°.

[0058] In some embodiments, the first passivation contact layer 110 includes a first tunneling dielectric layer 111 and a first doping semiconductor layer 112, wherein the first tunneling dielectric layer 111 is located in the first doping region 11, the first doping semiconductor layer 112 is located on the surface of the first tunneling dielectric layer 111, the passivation layer 133 is located on the surface of the first doping semiconductor layer 112, and the first electrode 104 is electrically connected to the first doping semiconductor layer 112.

[0059] The first doping semiconductor layer 112 can form energy band bending on the surface of the substrate 100, and the first tunneling dielectric layer 111 can asymmetrically offset the energy bands on the surface of the substrate 100 such that the potential barrier of the majority carriers is lower than the potential barrier of the minority carriers. As a result, the majority carriers can easily quantum tunnel through the first tunneling dielectric layer 111, while the minority carriers have difficulty passing through the first tunneling dielectric layer 111, thus achieving selective transport of carriers.

[0060] Furthermore, the first tunneling dielectric layer 111 exhibits a chemical passivation effect. Specifically, because interface state defects exist at the interface between the substrate 100 and the first tunneling dielectric layer 111, the interface density of states of the first surface 101 increases. This increase in interface density of states promotes the recombination of photogenerating carriers, thereby increasing the curve factor, short-circuit current, and open-circuit voltage of the back-contact solar cell, and thus improving the photoelectric conversion efficiency of the back-contact solar cell. By providing the first tunneling dielectric layer 111 on the first surface 101, the first tunneling dielectric layer 111 exhibits a chemical passivation effect on the surface of the substrate 100. Specifically, it saturates the dangling bonds of the substrate 100, reduces the defect density of states of the substrate 100, and decreases the recombination centers of the substrate 100, thereby reducing the carrier recombination rate.

[0061] The first doping semiconductor layer 112 exerts a field passivation effect. Specifically, it forms an electrostatic field directed inward towards the substrate 100 on the surface of the substrate 100, causing minority carriers to escape from the interface and reducing the minority carrier concentration. This reduces the carrier recombination rate at the substrate 100 interface, increasing the open-circuit voltage, short-circuit current, and curve factor of the back-contact solar cell, thereby improving the photoelectric conversion efficiency of the back-contact solar cell.

[0062] In some embodiments, the thickness of the first tunneling dielectric layer 111 is 0.5 nm to 10 nm. The thickness range of the first tunneling dielectric layer 111 is 0.5 nm to 1.3 nm, 1.3 nm to 4.6 nm, 4.6 nm to 6.1 nm, or 6.1 nm to 10 nm. If the thickness of the first tunneling dielectric layer 111 is within any of the above ranges, the thickness of the first tunneling dielectric layer 111 is small, making it easier for majority carriers to quantum tunnel through the first tunneling dielectric layer 111, while minority carriers have difficulty passing through the first tunneling dielectric layer 111, thus achieving selective carrier transport.

[0063] In some embodiments, the material of the first tunneling dielectric layer 111 includes at least one of silicon oxide, amorphous silicon, microcrystalline silicon, nanocrystalline silicon, or silicon carbide.

[0064] In some embodiments, the first doped semiconductor layer 112 includes at least one of a doped amorphous silicon layer, a doped polycrystalline silicon layer, a doped microcrystalline silicon layer, a doped silicon carbide layer, or a doped crystalline silicon layer.

[0065] In some embodiments, the second passivation contact layer 130 includes a second tunneling dielectric layer 131 and a second doping semiconductor layer 132, wherein the second tunneling dielectric layer 131 is located in a second region, the second doping semiconductor layer 132 is located on the surface of the second tunneling dielectric layer 131, the passivation layer 133 is located on the surface of the second doping semiconductor layer 132, and the second electrode 105 is electrically connected to the second doping semiconductor layer 132. One end of the connecting layer 140 is electrically connected to the second doping semiconductor layer 132.

[0066] The function, material, and thickness of the second tunneling dielectric layer 131 can be found in the description of the first tunneling dielectric layer 111 above. The function and material of the second doping semiconductor layer 132 can be found in the description of the first doping semiconductor layer 112 above.

[0067] The difference between the first doping semiconductor layer 112 and the second doping semiconductor layer 132 is that the first doping semiconductor layer 112 is either an N-type doping layer or a P-type doping layer, while the second doping semiconductor layer 132 is the other of either an N-type doping layer or a P-type doping layer.

[0068] In some embodiments, the doping elements in the first doping semiconductor layer 112 and the doping elements in the substrate 100 have the same conductivity type. For example, the substrate 100 may contain N-type doping elements, and the first doping semiconductor layer 112 may contain N-type doping elements, or the substrate 100 may contain P-type doping elements, and the first doping semiconductor layer 112 may contain P-type doping elements. Thus, the first doping semiconductor layer 112 and the substrate 100 have the same conductivity type of doping elements. By making the concentration of the doping elements in the first doping semiconductor layer 112 greater than the concentration of the doping elements in the substrate 100, a high-low junction is formed between the substrate 100 and the first doping semiconductor layer 112. Under the influence of the built-in electric field constructed by the high-low junction, carriers rapidly move from the substrate 100 into the first doping semiconductor layer 112 and are collected by the first electrode 104.

[0069] In response to this, the doping elements in the second doping semiconductor layer 132 and the doping elements in the substrate 100 have different conductivity types. For example, the substrate 100 may contain N-type doping elements and the second doping semiconductor layer 132 may contain P-type doping elements, or the substrate 100 may contain P-type doping elements and the second doping semiconductor layer 132 may contain N-type doping elements. In this way, the substrate 100 and the second doping semiconductor layer 132 form a PN junction, and minority carriers and majority carriers flow to the corresponding P-region and N-region under their respective forces, thereby improving carrier mobility.

[0070] In some other embodiments, the situation is reversed. For example, the doping elements in the first doping semiconductor layer 112 and the doping elements in the substrate 100 have different conductivity types, while the doping elements in the second doping semiconductor layer 132 and the doping elements in the substrate 100 have the same conductivity type. A detailed explanation is omitted here.

[0071] The doping oxide layer 120 improves the electric field distribution between the first passivation contact layer 110 and the connecting layer 140, and between the first passivation contact layer 110 and the substrate 100, by reducing the interfacial state charge on the surface of the first passivation contact layer 110, thereby avoiding the generation of large leakage currents and other adverse effects due to interfacial state charges. Next, the doping oxide layer 120 is located on part of the surface of the first passivation contact layer 110 and extends to the second doping region 12. In this way, an inwardly recessed structure is formed between the doping oxide layer 120, the first passivation contact layer 110, and the substrate 100, and the connecting layer 140, which is later deposited on this film layer, has a thickness that is less than or equal to the thickness of the second passivation contact layer 130 due to the shielding of the doping oxide layer 120. This reduces the size of the leakage current path and ensures a balance between leakage current and cell efficiency.

[0072] In some examples, the material of the doping oxide layer 120 includes borosilicate glass, phosphatesilicic acid glass, borosilicate glass, or phthalic acid glass.

[0073] In some examples, the thickness of the doping oxide layer 120 is 0 to 120 nm, and furthermore, the thickness of the doping oxide layer 120 is 10 nm to 50 nm. The thickness of the doping oxide layer is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, or 120 nm.

[0074] In some embodiments, the doping oxide layer 120 contains a doping element, which may be the first doping element of the first doping semiconductor layer 112. Since this doping element can act as a carrier, the effect of leakage current can be improved by electrically connecting the connecting layer 140 and the first doping semiconductor layer 112 via this doping element.

[0075] In some embodiments, the doping oxide layer 120 contains doping elements, which may be a first doping element in the first doping semiconductor layer 112 and a second doping element in the second doping semiconductor layer 132, with the doping concentration of the first doping element being greater than that of the second doping element. By adjusting the proportionality between the doping concentrations of the first and second doping elements, the interfacial charge recombination capability of the doping oxide layer 120 can be improved, and leakage current can be controlled. Next, by controlling the proportionality relationship between the concentrations of the first and second doping elements, the performance of the doping oxide layer 120 itself can be changed. At the very least, by increasing the fluidity of the doping oxide layer 120, defects in the first doping semiconductor layer 112 can be reduced, and the flatness of the first doping semiconductor layer 112 can be improved. At the very least, the decomposition capability of the doping oxide layer 120 is weakened, so that it does not decompose into acid during sodium ion absorption and affect the photoelectric conversion efficiency of the back-contact solar cell.

[0076] In some embodiments, the length range of the second portion 122 in the first direction is 0 to 3 μm, and the first direction Y is the direction from the second doping region 12 to the first doping region 11. The length of the second portion 122 also prevents the thickness of the connecting layer 140 located on the side surface 1120 from becoming too small, allowing for the construction of a leakage current path and reducing the hot spot effect. However, the shielding of the second portion 122 also prevents the thickness of the connecting layer 140 from becoming too large, and the size of the leakage current path is limited, thus preventing excessive electron and hole recombination and further significantly reducing the photoelectric conversion efficiency. The length of the second portion 122 in the first direction may be 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3 μm.

[0077] In some embodiments, the doping oxide layer 120 is located only in a portion of the first doping region 11 and not between the first electrode 104 and the first doping semiconductor layer 112. This avoids an increase in contact resistance between the first electrode 104 and the first doping semiconductor layer 112 due to the dielectric film characteristics of the doping oxide layer 120. Here, the aforementioned portion of the first doping region 11 refers to a portion of the first doping region 11 and a portion of the first doping region 11.

[0078] Figure 4 is a partially enlarged view of a back-contact solar cell provided according to one embodiment of the present invention.

[0079] Referring to Figure 4, in some embodiments, the first passivation contact layer 110 is doped with a P-type doping element, and the first passivation contact layer 110 includes a continuous third portion 1121 and a fourth portion 1122, the third portion 1121 is located in the groove 103 facing the first portion 121, the fourth portion 1122 is located facing the second portion 122, the second portion 122 is located on the surface of the fourth portion 1122, and the connecting layer 140 is located on the side of the fourth portion 1122 and on the bottom surface of the fourth portion 1122 away from the second portion 122. Thus, the first passivation contact layer 110 protrudes from the substrate 100 and is located above the groove 103, and the structure of the first passivation contact layer 110 forms a light trapping structure between the first passivation contact layer 110 and the substrate 100, increasing internal reflection.

[0080] The connecting layer 140 is located on the doping oxide layer 120 and is electrically connected to the second passivation contact layer 130. The connecting layer 140, located on the doping oxide layer 120, is indirectly in contact with the first passivation contact layer 110 via the doping oxide layer 120. Due to the dielectric film properties and low carrier mobility of the doping oxide layer 120 itself, the leakage current path formed by the connecting layer 140 through the doping oxide layer 120 is limited, which can slightly improve the hot spot effect but does not significantly reduce the photoelectric conversion efficiency. The connecting layer 140 is also in contact with the side surface 1120 of the first passivation contact layer 110. Thus, the connecting layer 140 is in direct contact with the first passivation contact layer 110, and one end of the connecting layer 140 is also in direct contact with the second passivation contact layer 130. This allows for the formation of direct leakage current pathways, significantly improving the hot spot effect. However, because the contact area of ​​the side surface 1120 is limited and the thickness of the connecting layer 140 located on the side surface is not excessively large due to limitations in the deposition process, the leakage current pathway in this area is also not excessively large, thus preventing an excessive reduction in photoelectric conversion efficiency. The hot spot effect is improved by two types of connection methods: indirect contact between the connecting layer 140 and the first passivation contact layer 110, and direct contact located on the side surface 1120. This ensures the yield of the final photovoltaic assembly and the photoelectric conversion efficiency of the back contact solar cell itself.

[0081] In some embodiments, the connecting layer 140 is in contact with the upper surface 123, side surface 124, and lower surface 125 of the doping oxide layer 120.

[0082] In some embodiments, the material of the connecting layer 140 may be any conductive material layer, such as a metal layer, a doped semiconductor layer, a transparent conductive layer, or a metallic nitride.

[0083] In some embodiments, the thickness of the connecting layer 140 is 80 nm to 240 nm. Furthermore, the thickness of the connecting layer 140 is 100 nm to 200 nm. The thickness of the connecting layer 140 is 80 nm, 100 nm, 130 nm, 150 nm, 180 nm, 210 nm, or 240 nm.

[0084] In some embodiments, the thickness of the connecting layer 140 is less than or equal to the thickness of the second passivation contact layer 130. By reducing the thickness of the connecting layer 140 in this way, the size of the connecting layer 140 as a leakage current path is reduced, and the leakage area is small, which reduces the amount of electron-hole recombination and improves the photoelectric conversion efficiency.

[0085] Figure 5 is another cross-sectional view along the A1-A2 section of Figure 1.

[0086] In some embodiments, referring to Figure 5, the connecting layer 140 and the second passivation contact layer 130 are made of the same material and are the same continuous film layer. The connecting layer 140 includes a stacked third tunneling dielectric layer 141 and a third doping semiconductor layer 142, the third tunneling dielectric layer 141 and the second tunneling dielectric layer 131 are made of the same material, and the third doping semiconductor layer 142 and the second doping semiconductor layer 132 are made of the same material. The thickness of the third tunneling dielectric layer 141 is less than or equal to the thickness of the second tunneling dielectric layer 131, and the thickness of the third doping semiconductor layer 142 is less than or equal to the thickness of the second doping semiconductor layer 132.

[0087] Figure 6 is a scanning electron microscope image of a back-contact solar cell provided according to one embodiment of the present invention.

[0088] In some embodiments, referring to Figure 6, the connection layer 140 includes a first connection layer 143 located in a portion of the first portion 121, and a second connection layer 144 surrounding a portion of the second portion 122 and electrically connected to the second passivation contact layer 130, with a thickness less than or equal to the thickness of the first connection layer 143.

[0089] In some embodiments, referring to Figure 6, the region of the second connection layer 144 connected to the second passivation contact layer 130 is the first connection region 1442, and the remaining second connection layer 140 is the second connection region 1441, which has a thickness greater than that of the first connection region 1442. By controlling the thickness of the connection layer 140 and the second passivation contact layer 130, the area of ​​the leakage current path is reduced, and the leakage current is further controlled.

[0090] Figure 7 is a partially enlarged view of the first passivation contact structure and substrate 100 in a back-contact solar cell provided according to one embodiment of the present invention. Figure 8 is a partially enlarged view of the first doping semiconductor layer 112 in the first passivation contact structure of Figure 7.

[0091] In some embodiments, referring to Figures 7 and 8, the side surface of the fourth portion 1122 (see Figure 4) has an inwardly recessed recess 160, and the connecting layer 140 is located inside the recess 160.

[0092] In some embodiments, referring again to Figure 2, the back-contact solar cell further includes a passivation layer 133 covering the first passivation contact layer 110, the connecting layer 140, and the second passivation contact layer 130.

[0093] In some embodiments, the passivation layer 133 may be a single-layer structure or a multi-layer structure, and the material of the passivation layer 133 may be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbon oxynitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0094] In some embodiments, the back-contact solar cell further includes an anti-reflective layer located on the surface of the passivation layer. The anti-reflective layer reduces or eliminates stray light in the system by reducing or eliminating reflected light from the surface of the back-contact solar cell. The material of the anti-reflective layer includes silicon nitride or silicon oxynitride.

[0095] Note that the scanning electron microscope image in Figure 6 shows that the back-contact solar cell includes a passivation layer and an anti-reflective layer located within the passivation layer, although the anti-reflective layer is not indicated. Next, the boundaries between each film layer are shown with dashed lines.

[0096] In some embodiments, the second surface 102 has a textured structure (not shown) that includes a plurality of pyramidal structures. The back-contact solar cell further includes a front passivation layer 106 that covers the textured structure 114.

[0097] In some embodiments, the front passivation layer 106 may be a single-layer or multi-layer structure, and the material of the front passivation layer 106 may be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbon oxynitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0098] In some embodiments, the front passivation layer 106 and the passivation layer 133 are made of the same material and manufactured using the same manufacturing process.

[0099] Referring again to Figure 2, the back-contact solar cell includes a first electrode 104 that is in electrical contact with the first doped semiconductor layer 112.

[0100] Referring again to Figure 2, the back-contact solar cell includes a second electrode 105 that is in electrical contact with the second doping semiconductor layer 132.

[0101] In some embodiments, either the first electrode 104 or the second electrode 105 may be sintered with a burn-through metal paste or with a LECO (laser-enhanced contact optimization) paste. The metal paste and LECO paste may contain at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0102] In some embodiments, the back surface may have an uneven structure. That is, at least one of the first doping region 11, the second doping region 12, and the isolation region may have an uneven structure, and the uneven structure can improve the utilization rate of incident light rays by increasing the internal reflection of incident light rays, and further improve the battery efficiency of the back contact solar cell.

[0103] Note that in Figures 2 and 5, the first electrode 104 penetrates the passivation layer and electrically contacts the first doping semiconductor layer 112, and the second electrode 105 penetrates the passivation layer and electrically contacts the second doping semiconductor layer 132, but this is merely an example. In an actual back-contact solar cell, the connection between the first electrode 104 and the first doping semiconductor layer 112 may be a contact connection or an indirect connection via conductive particles. The connection between the second electrode 105 and the second doping semiconductor layer 132 may be a contact connection or an indirect connection via conductive particles. The conductive particles may be silver crystals, silver aggregates, silver particles, or other conductive metal particles.

[0104] According to the back-contact solar cell provided by the embodiment of the present application, a first doping region 11 and a second doping region 12 are provided on the substrate 100, and a first passivation contact layer 110 and a second passivation contact layer 130 are formed in the first doping region 11 and the second doping region 12, respectively. Chemical passivation and field passivation of the first passivation contact layer 110 and the second passivation contact layer 130 reduce the carrier recombination rate on the surface of the substrate 100, thereby improving the photoelectric conversion efficiency of the back-contact solar cell. Next, a connecting layer 140 is provided, which is located on the doping oxide layer 120 and electrically connected to the second passivation contact layer 130. The connecting layer 140 located on the doping oxide layer 120 indirectly contacts the first passivation contact layer 110 via the doping oxide layer 120. Due to the dielectric film properties and low carrier mobility of the doping oxide layer 120 itself, the leakage current path formed by the connecting layer 140 through the doping oxide layer 120 is limited, which slightly improves the hot spot effect but does not significantly reduce the photoelectric conversion efficiency. The connecting layer 140 also contacts the side surface of the first passivation contact layer 110. Thus, the connecting layer 140 directly contacts the first passivation contact layer 110, and one end of the connecting layer 140 further directly contacts the second passivation contact layer 130. This allows for the formation of direct leakage current pathways, significantly improving the hot spot effect. However, because the contact area on the sides is limited and the thickness of the connecting layer 140 located on the sides is not excessively large due to limitations in the deposition process, the leakage current pathway in this area is also not excessively large, thus preventing an excessive reduction in photoelectric conversion efficiency. The hot spot effect is improved by two types of connection methods: indirect contact between the connecting layer 140 and the first passivation contact layer 110, and direct contact located on the sides. This ensures the yield of the final photovoltaic assembly and the photoelectric conversion efficiency of the back contact solar cell itself.

[0105] Thirdly, a doping oxide layer 120 is provided on a portion of the first passivation contact layer 110. The doping oxide layer 120 reduces the interfacial state charge on the surface of the first passivation contact layer 110, thereby improving the electric field distribution between the first passivation contact layer 110 and the connecting layer 140, and between the first passivation contact layer 110 and the substrate 100, thus avoiding the generation of large leakage currents and other adverse effects due to interfacial state charge. Next, the doping oxide layer 120 is located on the surface of a portion of the first passivation contact layer 110 and extends to the second doping region 12. In this way, an inwardly recessed structure is formed between the doping oxide layer 120, the first passivation contact layer 110, and the substrate 100, and the connecting layer 140, which is later deposited on this film layer, has a thickness that is less than or equal to the thickness of the second passivation contact layer 130 due to the shielding by the doping oxide layer 120. This reduces the size of the leakage current path and ensures a balance between leakage current and cell efficiency.

[0106] Accordingly, according to some embodiments of the present application, another aspect of the embodiments of the present application provides a method for manufacturing a back-contact solar cell for manufacturing the solar cell provided by the above embodiments, and a detailed description of the same or corresponding technical features as those of the above embodiments is omitted.

[0107] Figures 9 to 14 are cross-sectional views of a back-contact solar cell corresponding to each step in a method for manufacturing a back-contact solar cell provided by another embodiment of the present application.

[0108] Figures 9 to 14 illustrate a method for manufacturing a back-contact solar cell in which the connecting layer 140 and the second passivation contact layer 130 are connecting film layers. A different manufacturing method from that shown in Figure 1 will be explained below using a different embodiment, and parts that are not explained in detail are those in which the manufacturing method is the same or similar.

[0109] Referring to Figures 9 to 14, the manufacturing method includes the steps of: providing a substrate 100 having a first surface 101 and a second surface 102 arranged facing each other, with the first surface 101 being alternately arranged to form a first doping region 11 and a second doping region 12; forming a first passivation contact layer 110 located in the first doping region 11; and forming a first portion 121 located on the surface of the first passivation contact layer 110, and a second portion 122 extending along the edge of the first portion 121 toward the direction of the second doping region 12 so as to be located in the second doping region. The method includes the steps of forming a doping oxidation layer 120, forming a second passivation contact layer 130 located in the second doping region 12 and having a different doping type from the first passivation contact layer 110, and forming a connection layer 140 located in a portion of the first portion 121, surrounding a portion of the second portion 122 and electrically connected to the second passivation contact layer 130, and located on the side of the first passivation contact layer 110 and electrically connected to the first passivation contact layer 110.

[0110] Referring to Figure 9, the manufacturing method includes the step of providing a substrate 100 having a first surface 101 and a second surface 102 arranged facing each other, and having a first processing region and a second processing region in which the first surface 101 is arranged alternately, wherein the area of ​​the first processing region and the second processing region and the later formed first doping region 11 and second doping region 12 are different.

[0111] The first surface 101 and the second surface 102 of the substrate 100 are trimmed flat surfaces. The second surface 102 is subjected to texture processing. The texture processing includes chemical etching, for example, the original substrate 100 can be cleaned using a mixed solution of potassium hydroxide and hydrogen peroxide. Specifically, by controlling the concentration ratio of potassium hydroxide and hydrogen peroxide, a textured structure with the desired shape can be formed. In some embodiments, the textured structure may be formed using methods such as laser etching, mechanical processing, or plasma etching. In laser etching, a textured structure with the desired shape can be obtained by controlling the laser process parameters. The textured structure includes a plurality of pyramidal structures.

[0112] Referring to Figures 10 to 12, the steps of forming the first passivation contact layer 110 and the doping oxide layer 120 include the steps of forming a first dielectric film, a first doping film, and an oxide film on the first surface 101 of the substrate 100; partially removing the oxide film of the second doping region 12 to expose the surface of the first doping film; removing the first dielectric film and the first doping film of the second doping region 12; and, in the process of forming the second passivation contact layer 130, partially removing the oxide film located in the first doping region 11, making the remaining oxide film the doping oxide film, and making the remaining first dielectric film together with the first doping film the first passivation contact layer 110.

[0113] In some embodiments, the substrate 100 is provided with a first processing area 21 and a second processing area 22.

[0114] Specifically, referring to Figure 10, the manufacturing method includes the step of forming a first dielectric film 151, a first doping film 152, and an oxide film 153 in a first processing area 21 and a second processing area 22.

[0115] In one example, the steps of forming a first dielectric film 151, a first doping film 152, and an oxide film include: forming a first dielectric film 151 in a first processing region 21 and a second processing region 22 of a substrate 100 by chemical vapor deposition; forming a first amorphous silicon layer on the first dielectric film 151 by a PECVD process; forming a doping source layer on the surface of the first amorphous silicon layer by a PECVD process; and transferring some of the doping elements in the doping source layer to the first amorphous silicon layer by a doping process, crystallizing the first amorphous silicon layer to form a first doping film 152, and converting the doping source layer into an oxide film 153. In some embodiments, a thinning process is also performed on the formed oxide film 153 to reduce the thickness of the oxide film 153.

[0116] Referring to Figure 11, the oxide film 153 in the second processing area 22 is removed by patterning. The process for removing the oxide film 153 may be laser etching or a wet etching process.

[0117] Referring to Figure 12, the parameters for the process of removing the first doping film 152 from the second doping region 12, that is, removing the first doping film 152 from the second processing region 22, are as follows: the etching solution is an alkaline solution, the concentration ratio of the alkaline solution is 0.1 PPM (volume specific concentration, parts per million) to 0.6 PPM, the etching time is 20 s to 500 s, and the etching temperature is 50°C to 90°C.

[0118] The first doping film 152 in the second doping region 12 is removed, and at the same time, the substrate 100 is further etched to form grooves 103.

[0119] Referring to Figures 12 and 13, during the etching process, the etching solution also has etchability against the first doping film 152, and because the etching is isotropic, the substrate 100 and the first doping film 152, which are partially located in the first processing region 21 and beneath the oxide film, are back-etched, and an inwardly recessed structure is formed. The unetched edge region of the substrate 100 is defined as the boundary line between the first doping region 11 and the second doping region 12; that is, the unetched region of the substrate 100 is the first doping region 11, and the etched region is the second doping region 12.

[0120] Referring to Figure 13, the step of forming the second passivation contact layer 130 includes forming a second dielectric film 154 located on the surface of the doping oxide layer 120, the inner wall and bottom surfaces of the groove 103, and the side surface of the first passivation contact layer 110, and a second doping film 155 located on the surface of the second dielectric film 154, in the first doping region 11 and the second doping region 12.

[0121] Referring to Figure 14, the second dielectric film and second doping film in the first doping region 11, and a portion of the second dielectric film and second doping film located at the boundary between the first doping region 11 and the second doping region 12 are removed. Of these, the above-mentioned portion is removed because it is necessary to establish some leakage current paths as shown in Figure 1. Etching is not performed in the region where leakage current paths need to be constructed, and a mask is formed on top of it. The mask may contain one of the following: ink, paraffin, or a doped silicate glass layer. The etching process may include one of the following: a dry etching process, a wet etching process, or a laser etching process.

[0122] In some embodiments, the second dielectric film and the second doping film are removed, and at the same time, the exposed doping oxide film is also removed. The remaining second dielectric layer and second doping film are partially used as a connecting layer 140 and partially used as a second passivation contact layer 130.

[0123] In some other embodiments, the second dielectric film and the second doping film are removed from all regions located at the boundary between the first doping region and the second doping region, a second passivation contact layer is formed, and then a connecting layer is formed.

[0124] Continuing with Figure 5, a first doping semiconductor layer 112, a second doping semiconductor layer 132, a connecting layer 140, and a passivation layer 133 covering the boundary between the first doping region 11 and the second doping region 12 are formed, a first electrode 104 electrically connected to the first doping semiconductor layer 112 is formed, and a second electrode 105 electrically connected to the second doping semiconductor layer 132 is formed.

[0125] According to some embodiments of the present application, another embodiment of the present application provides a stack cell comprising a bottom cell which is a back-contact solar cell manufactured by the manufacturing method described in any one of the above embodiments, or a back-contact solar cell described in any one of the above embodiments, and a top cell which is located on the side of the bottom cell away from the front electrode of the substrate.

[0126] In some embodiments, the stacked cell has a first grid line for the first polarity and a second grid line for the second polarity, where the first grid line represents the first electrode of the back-contact solar cell and the second grid line represents the second electrode of the back-contact solar cell.

[0127] In some embodiments, there is an interfacial layer between the top cell and the bottom cell, which further covers the backside passivation contact structure.

[0128] The stacked cells in the embodiments of this application may be two-layer solar cells, three-layer solar cells, and multilayer stacked solar cells with four or more layers.

[0129] In some embodiments, the top cell may be a perovskite solar cell comprising a stacked first transport layer, a perovskite substrate, a second transport layer, a transparent conductive layer, and an anti-reflective layer. The first transport layer faces the bottom cell.

[0130] In some embodiments, the first transport layer may be either an electron transport layer or a hole transport layer, and the second transport layer may be the other of the electron transport layer or a hole transport layer.

[0131] According to some embodiments of the present application, yet another embodiment of the embodiments of the present application provides a photovoltaic assembly. Referring to Figure 15, the photovoltaic assembly includes a cell string composed of back-contact solar cells 30 described in any one of the above embodiments, or back-contact solar cells 30 manufactured by the manufacturing method described in any one of the above embodiments, a sealing film 31 covering the surface of the cell string, and a cover plate 32 covering the surface of the sealing film 31 away from the cell string. Figure 15 is a cross-sectional view of a photovoltaic assembly provided in yet another embodiment of the present application.

[0132] The connecting member 318 electrically connects two adjacent back-contact solar cells 30. Specifically, in some embodiments, multiple back-contact solar cells 30 may be electrically connected to each other by the connecting member 318, and the connecting member 318 and the main grid / subgrid of the back-contact solar cells 30 are welded together.

[0133] In some embodiments, the connecting member 318 and the subgate including the first and second electrodes of the cell sheet are welded together. In some embodiments, the connecting member 318 and the main grid of the cell sheet are welded together, and the main grid includes a first main grid welded to the first electrode and a second main grid welded to the second electrode.

[0134] In some embodiments, the sealing film 31 includes a first sealing film that covers either the front or back of the back-contact solar cell, and a second sealing film that covers the other of the front or back of the back-contact solar cell. Specifically, at least one of the first sealing film and the second sealing film may be an organic sealing film such as polyvinyl butyral (PVB) film, ethylene vinyl acetate copolymer (EVA) film, polyolefin elastomer (POE) film, or polyethylene terephthalate (PET) film.

[0135] Although the first sealing film and the second sealing film have a boundary line before lamination, once the solar power generation assembly is formed after lamination, the concepts of the first sealing film and the second sealing film no longer exist; in other words, the first sealing film and the second sealing film already form a single, integrated sealing film 31.

[0136] In some embodiments, the cover plate 32 may be a light-transmitting cover plate such as a glass cover plate or a plastic cover plate. Specifically, by making the surface of the cover plate 32 facing the sealing film 31 an uneven surface, the utilization rate of incident light rays can be increased. The cover plate 32 includes a first cover plate and a second cover plate, the first cover plate facing the first sealing film and the second cover plate facing the second sealing film, or the first cover plate facing one side of the back contact solar cell and the second cover plate facing the other side of the back contact solar cell.

[0137] While this application has disclosed preferred embodiments as described above, it is not intended to limit the scope of the claims. Those skilled in the art can make several possible changes and modifications without departing from the concept of this application, so the scope of protection of this application is limited to the scope defined by the claims. Furthermore, the embodiments and drawings shown in this specification are illustrative and do not represent the entire scope of protection provided by the claims.

[0138] Those skilled in the art will understand that the above embodiments are specific examples for carrying out the present application, and that in actual application, various formal and detailed modifications can be made without departing from the spirit and scope of the present application. Those skilled in the art can also make any changes and modifications without departing from the spirit and scope of the present application, so the scope of protection of the present application shall be limited to the scope defined by the claims.

Claims

1. A substrate having a first surface and a second surface facing each other, wherein the first surface is provided with a first doping region and a second doping region arranged alternately in a first direction, The first passivation contact layer located in the first doping region, A doping oxide layer comprising a first portion provided on the first passivation contact layer so as to be located in the first doping region, and a second portion extending in the first direction from the first portion so as to be located in the second doping region, A second passivation contact layer located in the second doping region and having a doping type different from the first passivation contact layer, A connecting layer located in a portion of the first part and electrically connected to both the first passivation contact layer and the second passivation contact layer, including, Back-contact solar cells.

2. The length range of the second portion in the first direction is 0 to 3 μm. The first direction is the direction from the second doping area toward the first doping area. The back-contact solar cell according to claim 1.

3. The first distance between the first doping area and the second surface is greater than the second distance between the second doping area and the second surface. The back-contact solar cell according to claim 1.

4. The second doping region has a groove relative to the first doping region, The second portion is located in the groove, The connecting layer is located on the inner side surface of the groove, The second passivation contact layer is located at the bottom surface of the groove, The back-contact solar cell according to claim 1.

5. The difference between the first distance and the second distance is 5 μm or less. The back-contact solar cell according to claim 3.

6. The first passivation contact layer is doped with a P-type doping element. The first passivation contact layer includes a continuous third portion and a fourth portion, The third part is opposite to the first part, The fourth portion is located in the groove opposite to the second portion, The second part is located on the surface of the fourth part, The connecting layer is located on the side surface of the fourth portion and on the bottom surface of the fourth portion that is separated from the second portion. The back-contact solar cell according to claim 4.

7. The side surface of the fourth portion has a recess that is inwardly recessed, The connecting layer is located inside the recess, The back-contact solar cell according to claim 6.

8. The angle between the bottom surface of the groove and the side surface of the groove is in the range of 110° to 150°. The back-contact solar cell according to claim 4.

9. The material of the doping oxide layer includes borosilicate glass, phosphatesilicic acid glass, borosilicate glass, or fluorine glass. The back-contact solar cell according to claim 1.

10. The thickness of the aforementioned connection layer is less than or equal to the thickness of the second passivation contact layer. The back-contact solar cell according to claim 1.

11. The connection layer includes a first connection layer located in a portion of the first portion, and a second connection layer surrounding a portion of the second portion and electrically connected to the second passivation contact layer, with a thickness less than or equal to the thickness of the first connection layer. The back-contact solar cell according to claim 1.

12. The region of the second connection layer connected to the second passivation contact layer is the first connection region, The remaining second connection layer is a second connection region whose thickness is greater than the thickness of the first connection region. The back-contact solar cell according to claim 11.

13. A cell string composed of back-contact solar cells according to any one of claims 1 to 12, A sealing film covering the surface of the cell string, A cover plate that covers the surface of the sealing film away from the cell string, A solar power assembly including a solar power generation system.

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