Back contact solar cell and method of manufacturing same, photovoltaic assembly

Abstract

The present invention provides a back-contact solar cell, a manufacturing method thereof, and a photovoltaic assembly in the field of photovoltaics. The back-contact solar cell includes a substrate and alternating first and second doped regions, a first passivation contact layer located in the first doped regions and a second passivation contact layer located in the second doped regions, a doped oxide layer including a first portion located on the surface of the first passivation contact layer and a second portion located in the second doped regions, and a connecting layer located on 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 a side of the first passivation contact layer and electrically connected to the first passivation contact layer. [Effects] At the very least, the hot spot effect can be improved and the photoelectric conversion efficiency can be increased.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION Embodiments of the present application relate to the field of photovoltaics, and more particularly to back contact solar cells and methods of fabrication and photovoltaic assemblies. [Background technology]

[0002] An IBC cell (Interdigitated Back Contact) 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 side of the cell, with the PN junction located on the back surface of the cell. Back junction refers to the PN junction being located on the back surface of the cell. IBC cells currently have one of the highest conversion efficiencies. These cells are based on single-crystal silicon, and both the PN junction and metal electrodes are located on the back surface of the cell, with no metal electrodes on the front surface to block light, allowing for very high short-circuit current and conversion efficiency.

[0003] Photovoltaic assemblies consisting of multiple cells are usually installed in spacious, sunny locations. Over time, it is inevitable that birds, dust, fallen leaves, and other obstructions will fall on the solar cell assemblies, casting shadows on them. In large solar cell assembly arrays, improper row spacing can also cause shadows on each other. The presence of localized shadows can cause changes in the current and voltage of some cell sheets in the solar cell assembly. As a result, the local current-voltage product of the solar cell assembly increases, resulting in localized temperature increases in these cell assemblies. Defects in some cell sheets of the solar cell assembly itself can also cause the assembly to generate localized heat during operation, a phenomenon known as the "hot spot effect."

[0004] In an IBC cell, both the P-type doped region and the N-type doped region are located on the backside of the substrate and are completely isolated. Therefore, when multiple IBC cells are used to form a cell string and then packaged into a photovoltaic assembly, the hot spot effect can affect the power of the photovoltaic assembly and cause safety issues due to localized temperature increases. Therefore, how to improve and resolve the "hot spot effect" is an issue that engineers today must urgently address. Summary of the Invention [Problem to be solved by the invention]

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

[0006] According to some embodiments of the present application, one aspect of the embodiments provides a back-contact solar cell, the back-contact solar cell including: a substrate having a first surface and a second surface arranged back-to-back, the first surface having alternating first and second doping regions; a first passivation contact layer located in the first doping region; a doping oxide layer including a first portion located on a surface of the first passivation contact layer and a second portion extending along an edge of the first portion toward 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 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, the connection layer located on a side of the first passivation contact layer and electrically connected to the first passivation contact layer.

[0007] In some embodiments, the second portion has a length in the first direction ranging from 0 to 3 μm, and the first direction is a direction from the second doped region to the first doped region.

[0008] In some embodiments, a first distance between the first doping region and the second surface is greater than a 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 connection layer is located on an inner side surface of the groove, and the second passivation contact layer is located on a 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, the first passivation contact layer includes a continuous third portion and a fourth portion, the third portion faces the first portion, the fourth portion is located in the groove so as to face the second portion, the second portion is located on a surface of the fourth portion, and the connection layer is located on a side surface of the fourth portion and a 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 portion, and the connection layer is located inside the recessed portion.

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

[0013] In some embodiments, the material of the doped oxide layer comprises borosilicate glass, phosphosilicate glass, borophosphosilicate glass, or fluorophosphate glass.

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

[0015] In some embodiments, 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, the second connection layer having a thickness equal to or less than the thickness of the first connection layer.

[0016] In some embodiments, the area of ​​the second connection layer that is connected to the second passivation contact layer is a first connection area, and the remaining part of the second connection layer is a second connection area having a thickness greater than that of the first connection area.

[0017] According to some embodiments of the present application, another aspect of the present application provides a method for manufacturing a back-contact solar cell, the method including the steps of: providing a substrate having a first surface and a second surface arranged back-to-back, the first surface having first doping regions and second doping regions arranged alternately; forming a first passivation contact layer located in the first doping region; forming a doped oxide layer including a first portion located on a surface of the first passivation contact layer and a second portion located in the second doping region, the second portion extending along an edge of the first portion toward 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, the second passivation contact layer having a doping type different from that of the first passivation contact layer; and forming a connection layer located on a portion of the first portion, surrounding a portion of the second portion, and electrically connected to the second passivation contact layer, the connection layer located on a 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 doped oxide layer include the steps of: forming a first dielectric film, a first doped film, and an oxide film on the first surface of the substrate; removing a portion of the oxide film in the second doped region to expose a surface of the first doped film; removing the first dielectric film and the first doped film in the second doped region; and, in the process of forming the second passivation contact layer, removing a portion of the oxide film located in the first doped region to form the remaining oxide film as a doped oxide film, and forming the remaining first dielectric film together with the first doped film as the first passivation contact layer.

[0019] In some embodiments, the process parameters for removing the first doping film of the second doping region are as follows: the etching solution is an alkaline solution, the concentration 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 aspect of the present application provides a photovoltaic assembly, the photovoltaic assembly including a cell string composed of the back contact solar cell described in any one of the above embodiments or back contact solar cells manufactured by the method for manufacturing a back contact solar cell described in any one of the above embodiments, an encapsulation film covering a surface of the cell string, and a cover plate covering a surface of the encapsulation film away from the cell string.

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

[0022] In the back-contact solar cell provided by the present application, a substrate is provided with a first doping region and a second doping region, and a first passivation contact layer and a second passivation contact layer are formed on 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. A connecting layer is then formed on the doping oxide layer and electrically connected to the second passivation contact layer. The connecting layer on the doping oxide layer indirectly contacts the first passivation contact layer through the doping oxide layer. Due to the dielectric film properties and low carrier mobility of the doping oxide layer itself, the leakage current path formed by the connecting layer through the doping oxide layer is limited, slightly improving the hot spot effect but without significantly reducing the photoelectric conversion efficiency. The connecting layer also contacts the side of the first passivation contact layer. In this way, the connection layer is in direct contact with the first passivation contact layer, and one end of the connection layer is also in direct contact with the second passivation contact layer. This creates a direct leakage current path and significantly reduces the hot spot effect. However, because the side contact area is limited and the thickness of the connection layer located on the side is not excessively large due to limitations in the deposition process, the leakage current path in this area is also not excessively large, preventing excessive reduction in photovoltaic conversion efficiency. The two connection methods, indirect contact between the connection layer and the first passivation contact layer and direct contact on the side, reduce the hot spot effect. This ensures the yield of the final photovoltaic assembly and the photovoltaic conversion efficiency of the back-contact solar cell itself.

[0023] Third, a doped oxide layer is provided on a portion of the first passivation contact layer. The doped oxide layer reduces interface state charges on the surface of the first passivation contact layer, improving the electric field distribution between the first passivation contact layer and the connecting layer and between the first passivation contact layer and the substrate, thereby avoiding large leakage currents and other adverse effects caused by interface state charges. Second, the doped oxide layer is located on the surface of a portion of the first passivation contact layer and extends to the second doped region. This creates an inward-recessed structure between the doped oxide layer, the first passivation contact layer, and the substrate. The thickness of the connecting layer subsequently deposited on this film layer is less than or equal to the thickness of the second passivation contact layer, due to the shielding effect of the doped oxide layer. This reduces the size of the leakage current path and ensures a balance between leakage current and cell efficiency. [Brief explanation of the drawings]

[0024] One or more embodiments are illustratively illustrated by corresponding images in drawings, and these illustrative descriptions do not constitute limitations on the embodiments, and unless otherwise specified, the images in the drawings do not constitute limitations on proportion. In order to more clearly explain the embodiments of the present application or the technical solutions of the prior art, the drawings required for the embodiments will be briefly described below. It is clear that the accompanying drawings in the following description are only some embodiments of the present application, and those skilled in the art can derive other drawings based on these drawings without any creative effort. [Figure 1] 1 is a plan view of a back contact solar cell provided in accordance with one embodiment of the present application. [Figure 2] FIG. 2 is a cross-sectional view taken along the line A1-A2 of FIG. [Figure 3] FIG. 3 is a partial enlarged view of B in FIG. 2. [Figure 4] 1 is a partial enlarged view of a back contact solar cell provided in accordance with one embodiment of the present application. [Figure 5] FIG. 2 is another cross-sectional view taken along the A1-A2 cross section of FIG. [Figure 6]1 is a scanning electron microscope view of a back contact solar cell provided in accordance with one embodiment of the present application. [Figure 7] 2 is a partial enlarged view of a first passivation contact structure and a substrate in a back-contact solar cell provided in accordance with an embodiment of the present application. [Figure 8] 8 is a partial enlarged view of a first doping semiconductor layer in the first passivation contact structure of FIG. 7. FIG. [Figure 9] 1A-1C are cross-sectional views of a back contact solar cell corresponding to various steps in a method for fabricating a back contact solar cell provided in accordance with another embodiment of the present application. [Figure 10] 1A-1C are cross-sectional views of a back contact solar cell corresponding to various steps in a method for fabricating a back contact solar cell provided in accordance with another embodiment of the present application. [Figure 11] 1A-1C are cross-sectional views of a back contact solar cell corresponding to various steps in a method for fabricating a back contact solar cell provided in accordance with another embodiment of the present application. [Figure 12] 1A-1C are cross-sectional views of a back contact solar cell corresponding to various steps in a method for fabricating a back contact solar cell provided in accordance with another embodiment of the present application. [Figure 13] 1A-1C are cross-sectional views of a back contact solar cell corresponding to various steps in a method for fabricating a back contact solar cell provided in accordance with another embodiment of the present application. [Figure 14] 1A-1C are cross-sectional views of a back contact solar cell corresponding to various steps in a method for fabricating a back contact solar cell provided in accordance with another embodiment of the present application. [Figure 15] 1 is a cross-sectional view of a photovoltaic assembly provided in accordance with yet another embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0025] As can be seen from the background art, conventional back contact solar cells suffer from hot spot effects and have poor photoelectric conversion efficiencies.

[0026] The present application provides a back-contact solar cell, a manufacturing method thereof, and a photovoltaic assembly, in which a doped oxide layer is provided in the back-contact solar cell to improve the interface state charge of a first passivation contact layer and a connecting layer, and a doped oxide layer is provided in a second doped region to reduce the thickness of the connecting layer, and the connecting layer is provided so that the connecting layer 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, thereby forming a leakage current path and improving the hot spot effect, 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 the present application, the technical terms "first," "second," etc. are merely used to distinguish different objects, and should not be understood as indicating or implying relative importance, or implicitly specifying the number, specific order, or hierarchical relationship of the presented technical features. In the description of the embodiments of the present application, unless otherwise clearly and specifically limited, "plurality" means two or more.

[0028] References to "an embodiment" herein mean that a particular feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of the present application. The term appears in various places in this specification, but does not necessarily refer to the same embodiment, nor does it refer to separate or alternative embodiments that are mutually exclusive of other embodiments. Those skilled in the art will understand, both explicitly and implicitly, that the embodiments described herein may be combined with other embodiments.

[0029] In the description of the embodiments of the present 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, three situations can be represented: A exists, A and B exist simultaneously, and B exists. In this specification, the symbol " / " usually indicates that the related objects before and after it are in an "or" relationship.

[0030] In describing the examples of the present application, the term "plurality" means two or more (including two); similarly, "multiple sets" means two or more (including two sets), and "multiple sheets" means two or more (including two sheets).

[0031] In describing the embodiments of the present application, the orientations or positional relationships indicated by the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "upper and lower," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial direction," "radial direction," and "circumferential direction" are orientations or positional relationships shown in the drawings, and are intended solely for the convenience and simplification of the description of the embodiments of the present application. They do not state or imply that the devices or elements referred to must necessarily have a specific orientation, or be configured or operated in a specific orientation, and therefore should not be understood as limitations on the embodiments of the present application.

[0032] In describing the embodiments of the present application, unless otherwise clearly specified or limited, technical terms such as "attached," "interconnected," "connected," and "fixed" should be understood in a broad sense. For example, they may be fixedly connected, detachably connected, or integrally connected. They may be mechanically connected or electrically connected. They may be directly connected, indirectly connected through an intermediate medium, or may refer to internal communication between two elements or an interactive relationship between two elements. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application according to specific circumstances.

[0033] In the drawings corresponding to the embodiments of the present application, the thickness and area of ​​layers are exaggerated for better understanding and ease of explanation. When describing one component (e.g., a layer, film, region, or substrate) as being on or on the surface of another component, the component may be located "directly" on the surface of the other component, or a third component may be present between the two components. Conversely, when describing one component as being formed on the surface of another component, or another component formed or placed on the surface of one component, it means that there is no third component between the two components. Furthermore, when describing one component as being "substantially" formed on another component, it means that the component is not formed over the entire surface (or front surface) of the other component, but is not formed on only a portion of the edge of the entire surface.

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

[0035] The terms used in the description of the various embodiments herein above are used only to describe particular embodiments and are not intended to be limiting. As used in the description of the various embodiments described and in the appended claims, "the portions" includes the plural form unless the context clearly indicates otherwise. Components include components such as layers, films, regions, or plates.

[0036] Each embodiment of the present application will be described in detail below in conjunction with the drawings. However, those skilled in the art will understand that many technical details are presented in each embodiment of the present application to help readers better understand the present application. However, the technical proposal sought to be protected by the present application can be realized without these technical details and various changes and modifications based on the following embodiments.

[0037] Figure 1 is a plan view of a back-contact solar cell provided by one embodiment of the present application, Figure 2 is a cross-sectional view taken along the A1-A2 section of Figure 1, and Figure 3 is an enlarged view of a portion B of Figure 2.

[0038] 1 to 3, according to some embodiments of the present application, one aspect of the embodiments provides a back-contact solar cell, the back-contact solar cell having a first surface 101 and a second surface 102 provided back-to-back, the first surface 101 having a substrate 100 with first doping regions 11 and second doping regions 12 arranged alternately, a first passivation contact layer 110 located in the first doping region 11, a first portion 121 located on a surface of the first passivation contact layer 110, and a second portion 121 located along an edge of the first portion 121 so as to be located in the second doping region 12. the doped oxide layer 120 including a second portion 122 extending in the direction of the second doped region 12; a second passivation contact layer 130 located in the second doped region 12 and having a doping type different from that of the first passivation contact layer 110; and a connection layer 140 located in a partial region of the first portion 121, surrounding a partial region of the second portion 122 and electrically connected to the second passivation contact layer 130, located on a 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 a substrate 100, and a first passivation contact layer 110 and a second passivation contact layer 130 are formed on the first doping region 11 and the second doping region 12, respectively. The 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 on the doping oxide layer 120 and electrically connected to the second passivation contact layer 130. The connecting layer 140, located on the doped oxide layer 120, indirectly contacts the first passivation contact layer 110 via the doped oxide layer 120. Due to the dielectric film properties and low carrier mobility of the doped oxide layer 120 itself, the leakage current path formed by the connecting layer 140 through the doped oxide layer 120 is limited, slightly improving the hot spot effect without significantly reducing photoelectric conversion efficiency. The connecting layer 140 also contacts the side 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 a direct leakage current path, significantly reducing the hot spot effect. However, because the side contact area is limited and the thickness of the connecting layer 140 located on the side is not excessively large due to limitations in the deposition process, the leakage current path in this area is also not excessively large, preventing excessive reduction in photovoltaic conversion efficiency. The two connection methods of indirect contact between the connecting layer 140 and the first passivation contact layer 110 and direct contact located on the side reduce the hot spot effect. This ensures the yield of the final photovoltaic assembly and the photovoltaic conversion efficiency of the back-contact solar cell itself.

[0040] Third, a doped oxide layer 120 is provided on a portion of the first passivation contact layer 110. The doped oxide layer 120 reduces the interface 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, thereby avoiding the generation of large leakage currents and other adverse effects caused by the interface state charge. Next, the doped oxide layer 120 is located on the surface of a portion of the first passivation contact layer 110 and extends to the second doped region 12. In this way, an inward-recessed structure is formed between the doped oxide layer 120, the first passivation contact layer 110, and the substrate. The connecting layer 140, which is subsequently deposited on this film layer, has a thickness equal to or less than that of the second passivation contact layer 130 due to the shielding effect of the doped 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 may be composed of a single element, such as silicon or germanium. The elemental semiconductor material may be in a monocrystalline state, a polycrystalline state, an amorphous state, or a microcrystalline state (a state that simultaneously has a monocrystalline state and an amorphous state is called a microcrystalline state). For example, silicon may be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

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

[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 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 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 and back are relative terms; that is, "front" refers to the surface facing the sunlight in a vertical direction, and "back" refers to the surface facing away from the sunlight in a vertical direction.

[0045] In some embodiments, the back contact solar cell is a single-sided cell, with the front side being a light receiving side that receives incident light and the back side being a non-light receiving side, where the non-light receiving side can also receive incident light, but only slightly less efficiently than the light receiving side.

[0046] In some embodiments, the back contact solar cell is a bifacial cell, i.e., both the front and back surfaces of the substrate can be light receiving surfaces capable of receiving incident light.

[0047] In some embodiments, the first doping region 11 refers to the region where the orthogonal 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 orthogonal 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. The separation region means a region where the orthogonal projections of the first electrode 104 and the second electrode 105 onto the reference plane do not overlap, i.e., the separation region is a functional region that does not form a metallic electrode. In some other embodiments, there is no separation region between the first doping region 11 and the second doping region 12, and there is a height difference 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 contact each other.

[0049] To ensure that the film layers in contact with the first electrode 104 and the second electrode 105 are the corresponding functional film layers, the area of ​​the first doping region 11 is set to be equal to or larger than the area of ​​the orthogonal projection of the first electrode 104 onto the reference plane. That is, any orthogonal projection of the first electrode 104 onto the reference plane is located within the first doping region 11, and the distance between the edge of the first doping region 11 and the edge of the orthogonal projection pattern is equal to or larger than 0. Similarly, the area of ​​the second doping region 12 is equal to or larger than the area of ​​the orthogonal projection of the second electrode 105 onto the reference plane. The reference plane is a plane perpendicular to the thickness direction Z of the substrate 100. The reference plane is parallel to the plane defined by the second direction X and the first direction Y.

[0050] The first doping region 11, the second doping region 12, and the isolation region are functionally divided regions of the substrate 100 (or the first surface 101) to explain the distribution of each film layer structure of a back-contact solar cell, and all three actually belong to the substrate 100 (or the first surface 101). There are no boundaries between the different regions; only the film layers located there may be different. For example, the first doping region 11 has a first passivation contact layer 110, the second doping region 12 has a second passivation contact layer 130, most of the isolation region has a passivation layer, and some of the region has a connection layer 140.

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

[0052] In some embodiments, a first distance between the first doping region 11 and the second surface 102 is greater than a 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 connection layer 140 is located on the inner side 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 FIG. 2 , the difference between the first distance and the second distance is 5 μm or less, i.e., 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 having a concave-convex structure, and the groove 103 enhances the refractive index of incident light, thereby improving the photoelectric conversion efficiency of the back-contact solar cell. Next, because 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 typically less than 2 μm, the height difference between the first doping region 11 and the second doping region 12 itself fulfills the function of the separation region, eliminating the need for an additional separation region. This increases the carrier collection area and improves the carrier photoelectric conversion efficiency.

[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 depth to which the substrate 100 is etched can be controlled, and while ensuring that the first passivation contact layer 110 of the second doping region 12 is completely etched, the etching of the substrate 100 can be reduced, and adverse effects caused by excessive etching of the substrate 100 can be avoided. Next, the etching time and amount of etching solution for the substrate 100 can be reduced, thereby reducing manufacturing costs.

[0055] Specifically, the depth h of the recessed 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 of the groove 103 and the side surface of the groove 103 ranges from 110° to 150°. Thus, an obtuse angle is formed between the bottom surface of the groove 103 and the side surface of the groove 103, and the side surface of the groove 103 is inclined relative to the bottom surface, thereby enhancing the internal reflectivity of incident light. The inclined surface ensures that the thickness of the connecting layer 140 at least in that area 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 doped semiconductor layer 112, the first tunneling dielectric layer 111 is located in the first doped region 11, the first doped 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 doped semiconductor layer 112, and the first electrode 104 is electrically connected to the first doped 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 band on the surface of the substrate 100 so that the potential barrier of the majority carriers among the carriers is lower than the potential barrier of the minority carriers among the carriers, thereby making it easier for the majority carriers to quantum tunnel through the first tunneling dielectric layer 111 and harder for the minority carriers to pass through the first tunneling dielectric layer 111, thereby realizing selective transport of carriers.

[0060] The first tunneling dielectric layer 111 also exhibits a chemical passivation effect. Specifically, the presence of interface state defects at the interface between the substrate 100 and the first tunneling dielectric layer 111 increases the interface state density at the first surface 101. The increased interface state density promotes the recombination of photogenerated carriers and increases the fill factor, short-circuit current, and open-circuit voltage of the back-contact solar cell, thereby 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 the effect of chemically passivating the surface of the substrate 100. Specifically, the first tunneling dielectric layer 111 saturates dangling bonds in the substrate 100, reduces the defect state density in the substrate 100, and reduces the number of recombination centers in the substrate 100, thereby slowing the carrier recombination rate.

[0061] The first doped semiconductor layer 112 exhibits a field passivation effect by forming an electrostatic field on the surface of the substrate 100 that is directed toward the interior of the substrate 100, causing minority carriers to escape from the interface and reducing the minority carrier concentration, thereby reducing the carrier recombination rate at the interface of the substrate 100, increasing the open circuit voltage, short circuit current, and fill factor of the back contact solar cell, and 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 of the first tunneling dielectric layer 111 is in the range of 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, and majority carriers easily undergo quantum tunneling through the first tunneling dielectric layer 111, while minority carriers have difficulty passing through the first tunneling dielectric layer 111, thereby realizing 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 comprises 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 doped semiconductor layer 132, the second tunneling dielectric layer 131 is located in the second region, the second doped semiconductor layer 132 is located on a surface of the second tunneling dielectric layer 131, the passivation layer 133 is located on a surface of the second doped semiconductor layer 132, and the second electrode 105 is electrically connected to the second doped semiconductor layer 132. One end of the connection layer 140 is electrically connected to the second doped semiconductor layer 132.

[0066] The function, material, and thickness of the second tunneling dielectric layer 131 can be determined by referring to the description of the first tunneling dielectric layer 111. The function and material of the second doped semiconductor layer 132 can be determined by referring to the description of the first doped semiconductor layer 112.

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

[0068] In some embodiments, the doping elements in the first doped semiconductor layer 112 and the doping elements in the substrate 100 have the same conductivity type, for example, there is an N-type doping element in the substrate 100 and an N-type doping element in the first doped semiconductor layer 112, or there is a P-type doping element in the substrate 100 and a P-type doping element in the first doped semiconductor layer 112. Thus, the first doped semiconductor layer 112 and the substrate 100 have the same conductivity type of doping elements, and by making the concentration of the doping element in the first doped semiconductor layer 112 greater than the concentration of the doping element in the substrate 100, a high-low junction is formed between the substrate 100 and the first doped semiconductor layer 112. Under the action of a built-in electric field established by the high-low junction, carriers quickly move from the substrate 100 into the first doped semiconductor layer 112 and are collected by the first electrode 104.

[0069] Correspondingly, the doping elements in the second doped semiconductor layer 132 and the doping elements in the substrate 100 have different conductivity types, for example, there is an N-type doping element in the substrate 100 and a P-type doping element in the second doped semiconductor layer 132, or there is a P-type doping element in the substrate 100 and an N-type doping element in the second doped semiconductor layer 132. In this way, the substrate 100 and the second doped semiconductor layer 132 form a PN junction, and minority carriers and majority carriers flow into the corresponding P region and N region under the respective forces, thereby improving carrier mobility.

[0070] In some other embodiments, the above situation is reversed, for example, the doping elements in the first doped semiconductor layer 112 and the doping elements in the substrate 100 have different conductivity types, and the doping elements in the second doped semiconductor layer 132 and the doping elements in the substrate 100 have the same conductivity type, which will not be described in detail here.

[0071] The doped oxide layer 120 reduces the interface 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, and thus preventing large leakage currents and other adverse effects caused by the interface state charge. The doped oxide layer 120 is located on the surface of a portion of the first passivation contact layer 110 and extends to the second doped region 12. This creates an inward-recessed structure between the doped oxide layer 120, the first passivation contact layer 110, and the substrate 100. The connecting layer 140, which is subsequently deposited on this film layer, has a thickness equal to or less than that of the second passivation contact layer 130 due to the shielding effect of the doped 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 embodiments, the material of doped oxide layer 120 includes borosilicate glass, phosphosilicate glass, borophosphosilicate glass, or fluorophosphate glass.

[0073] In some embodiments, the thickness of the doped oxide layer 120 is 0 to 120 nm, and further, the thickness of the doped oxide layer 120 is 10 nm to 50 nm, the thickness of the doped 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 doped oxide layer 120 contains a doping element, which may be the first doping element of the first doped semiconductor layer 112. Since the doping element can serve as a carrier, the effect of leakage current can be improved by electrically connecting the connection layer 140 and the first doped semiconductor layer 112 through the doping element.

[0075] In some embodiments, the doping oxide layer 120 contains a doping element, 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 the doping concentration of the second doping element. Adjusting the proportional relationship between the doping concentrations of the first doping element and the second doping element can improve the interface state charge recombination ability of the doping oxide layer 120 and further control leakage current. Controlling the proportional relationship between the concentrations of the first doping element and the second doping element can also change the performance of the doping oxide layer 120, at least enhancing the fluidity of the doping oxide layer 120, thereby reducing defects in the first doping semiconductor layer 112 and improving the flatness of the first doping semiconductor layer 112. At the very least, the doping oxide layer 120's decomposition ability is weakened, and it subsequently decomposes into acid upon absorbing sodium ions, without affecting the photoelectric conversion efficiency of the back-contact solar cell.

[0076] In some embodiments, the length of the second portion 122 in the first direction is in the range of 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 connection layer 140 located on the side surface 1120 from becoming too small, creating a leakage current path and reducing the hot spot effect. However, due to the shielding provided by the second portion 122, the thickness of the connection layer 140 is also prevented from becoming too large, and the size of the leakage current path is limited, preventing the recombination of many electrons and holes and 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 regions 11, and is not located between the first electrode 104 and the first doping semiconductor layer 112, thereby preventing an increase in contact resistance between the first electrode 104 and the first doping semiconductor layer 112 due to the dielectric film properties of the doping oxide layer 120. Here, the aforementioned "a portion of the first doping regions 11" refers to a portion of the first doping regions 11 and a portion of the first doping regions 11.

[0078] FIG. 4 is a partial enlarged view of a back contact solar cell provided in accordance with one embodiment of the present application.

[0079] 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, where the third portion 1121 faces the first portion 121, the fourth portion 1122 faces the second portion 122, and the second portion 122 faces the surface of the fourth portion 1122. 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. 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, which increases internal reflection.

[0080] The connecting layer 140 is located on the doped oxide layer 120 and is electrically connected to the second passivation contact layer 130. The connecting layer 140 located on the doped oxide layer 120 indirectly contacts the first passivation contact layer 110 through the doped oxide layer 120. Due to the dielectric film properties and low carrier mobility of the doped oxide layer 120 itself, the leakage current path formed by the connecting layer 140 through the doped 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 also contacts 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 a direct leakage current path to be formed, significantly reducing 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 path in this area is also not excessively large, preventing excessive reduction in photovoltaic conversion efficiency. The two connection methods of indirect contact between the connecting layer 140 and the first passivation contact layer 110 and direct contact on the side surface 1120 reduce the hot spot effect. This ensures the yield of the final photovoltaic assembly and the photovoltaic conversion efficiency of the back-contact solar cell itself.

[0081] In some embodiments, the connecting layer 140 contacts all of the top surface 123 , the side surface 124 , and the bottom surface 125 of the doped oxide layer 120 .

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

[0083] In some embodiments, the thickness of the connecting layer 140 is between 80 nm and 240 nm. Further, the thickness of the connecting layer 140 is between 100 nm and 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 equal to or less than 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 reduced, thereby reducing the amount of recombination of electrons and holes and improving photoelectric conversion efficiency.

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

[0086] 5 , in some embodiments, 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 third tunneling dielectric layer 141 and a third doped semiconductor layer 142 stacked together, where the third tunneling dielectric layer 141 and the second tunneling dielectric layer 131 are made of the same material, and the third doped semiconductor layer 142 and the second doped semiconductor layer 132 are made of the same material. The thickness of the third tunneling dielectric layer 141 is equal to or less than the thickness of the second tunneling dielectric layer 131, and the thickness of the third doped semiconductor layer 142 is equal to or less than the thickness of the second doped semiconductor layer 132.

[0087] FIG. 6 is a scanning electron microscope view of a back contact solar cell provided in accordance with one embodiment of the present application.

[0088] In some embodiments, referring to FIG. 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, the second connection layer 144 having a thickness equal to or less than the thickness of the first connection layer 143.

[0089] 6, in some embodiments, the region of the second connection layer 144 that connects to the second passivation contact layer 130 is a first connection region 1442, and the remaining second connection layer 140 is a second connection region 1441 whose thickness is 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 can be reduced and the leakage current can be further controlled.

[0090] 7 is a partial enlarged view of a first passivation contact structure and substrate 100 in a back-contact solar cell provided in accordance with one embodiment of the present application. FIG. 8 is a partial enlarged view of a first doped semiconductor layer 112 in the first passivation contact structure of FIG. 7.

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

[0092] In some embodiments, with continued reference to FIG. 2, the back contact solar cell further includes a passivation layer 133 overlying the first passivation contact layer 110, the connecting layer 140, and the second passivation contact layer .

[0093] In some embodiments, the passivation layer 133 may be a single layer structure or a multilayer structure, and the material of the passivation layer 133 may be one or more of materials such as 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 comprises an anti-reflective layer located on the surface of the passivation layer. The anti-reflective layer increases the amount of light transmitted through the surface of the back contact solar cell by reducing or eliminating light reflected from the surface of the back contact solar cell, thereby reducing or eliminating stray light in the system. The material of the anti-reflective layer comprises silicon nitride or silicon oxynitride.

[0095] It should be noted that the scanning electron microscope image of Figure 6 shows that the back contact solar cell includes a passivation layer and an anti-reflection layer located on the passivation layer, but the anti-reflection layer is not labeled. Next, the boundaries between each film layer are indicated by 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 structure or a multilayer structure, and the material of the front passivation layer 106 may be one or more of materials such as 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 are manufactured in the same manufacturing process.

[0099] With continued reference to FIG. 2, the back contact solar cell includes a first electrode 104 in electrical contact with a first doped semiconductor layer 112 .

[0100] With continued reference to FIG. 2, the back contact solar cell includes a second electrode 105 in electrical contact with the second doped 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 a laser enhanced contact optimization (LECO) paste. The metal paste and the LECO paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0102] In some embodiments, the back surface may have a textured structure, i.e., at least one of the first doping region 11, the second doping region 12, and the isolation region may have a textured structure, which can increase the internal reflection of incident light, thereby improving the utilization of incident light and further improving the cell efficiency of the back contact solar cell.

[0103] 2 and 5 show the first electrode 104 electrically contacting the first doped semiconductor layer 112 through the passivation layer, and the second electrode 105 electrically contacting the second doped semiconductor layer 132 through the passivation layer, but this is merely an example. In an actual back-contact solar cell, the connection between the first electrode 104 and the first doped semiconductor layer 112 may be a direct contact or an indirect connection via conductive particles. The connection between the second electrode 105 and the second doped semiconductor layer 132 may be a direct contact 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 a substrate 100, and a first passivation contact layer 110 and a second passivation contact layer 130 are formed on the first doping region 11 and the second doping region 12, respectively. The chemical passivation and field passivation of the first passivation contact layer 110 and the second passivation contact layer 130 can reduce the carrier recombination rate on the surface of the substrate 100 and improve the photoelectric conversion efficiency of the back contact solar cell. Next, a connecting layer 140 is provided on the doping oxide layer 120 and electrically connected to the second passivation contact layer 130. The connecting layer 140, located on the doped oxide layer 120, indirectly contacts the first passivation contact layer 110 via the doped oxide layer 120. Due to the dielectric film properties and low carrier mobility of the doped oxide layer 120 itself, the leakage current path formed by the connecting layer 140 through the doped oxide layer 120 is limited, slightly improving the hot spot effect without significantly reducing photoelectric conversion efficiency. The connecting layer 140 also contacts the side 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 a direct leakage current path, significantly reducing the hot spot effect. However, because the side contact area is limited and the thickness of the connecting layer 140 located on the side is not excessively large due to limitations in the deposition process, the leakage current path in this area is also not excessively large, preventing excessive reduction in photovoltaic conversion efficiency. The two connection methods of indirect contact between the connecting layer 140 and the first passivation contact layer 110 and direct contact located on the side reduce the hot spot effect. This ensures the yield of the final photovoltaic assembly and the photovoltaic conversion efficiency of the back-contact solar cell itself.

[0105] Third, a doped oxide layer 120 is provided on a portion of the first passivation contact layer 110. The doped oxide layer 120 reduces the interface 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, and preventing large leakage currents and other adverse effects caused by the interface state charge. Second, the doped oxide layer 120 is located on the surface of a portion of the first passivation contact layer 110 and extends to the second doped region 12. In this way, an inwardly recessed structure is formed between the doped oxide layer 120, the first passivation contact layer 110, and the substrate 100. The thickness of the connecting layer 140, which will be deposited later on this film layer, is less than or equal to the thickness of the second passivation contact layer 130 due to the shielding effect of the doped 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 present application provides a method for manufacturing a back-contact solar cell for manufacturing the solar cell provided by the above example, and detailed descriptions of technical features that are the same as or correspond to those of the above example will be omitted.

[0107] 9-14 are cross-sectional views of a back contact solar cell corresponding to different steps in a method of fabricating a back contact solar cell according to another embodiment of the present application.

[0108] 9 to 14 show an example of a method for manufacturing a back-contact solar cell in which the connection layer 140 and the second passivation contact layer 130 are used as connection film layers. Manufacturing methods that differ from those shown in FIG. 1 will be explained below using other examples, and for parts that are not explained in detail, the manufacturing methods are the same or similar.

[0109] 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 back to back, the first surface 101 having first doping regions 11 and second doping regions 12 arranged alternately; 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 an end of the first portion 121 toward the second doping region 12 so as to be located in the second doping region 12. forming a doped oxide layer 120 including a doping type different from that of the first passivation contact layer 110, and forming a second passivation contact layer 130 located in the second doping region 12 and having a doping type different from that of 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 a side of the first passivation contact layer 110 and electrically connected to the first passivation contact layer 110.

[0110] Referring to FIG. 9, the manufacturing method includes the steps of providing a substrate 100 having a first surface 101 and a second surface 102 arranged back to back, with the first surface 101 having first processing regions and second processing regions arranged alternately, and the first processing regions and the second processing regions have different areas from the first doping regions 11 and second doping regions 12 to be formed later.

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

[0112] 10 to 12, the steps of forming the first passivation contact layer 110 and the doped 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, removing a portion of the oxide film in the second doping region 12 to expose the surface of the first doping film, removing the first dielectric film and the first doping film in the second doping region 12, and in the process of forming the second passivation contact layer 130, removing a portion of the oxide film located in the first doping region 11, making the remaining oxide film a doped 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 region 21 and a second processing region 22 .

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

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

[0116] 11, the oxide film 153 in the second processing region 22 is patterned and removed. The process for removing the oxide film 153 may be a laser etching or wet etching process.

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

[0118] At the same time as removing the first doping film 152 in the second doping region 12, the substrate 100 is still etched to further form the groove 103.

[0119] 12 and 13, during the etching process, the etchant has an etching ability also for the first doped film 152, and the etching is isotropic, so that the substrate 100 and the first doped film 152, which are partially located in the first processing region 21 and located under the oxide film, are back-etched, and a recessed structure is formed. The unetched edge region of the substrate 100 is defined as the boundary between the first doped region 11 and the second doped region 12. That is, the unetched region of the substrate 100 is the first doped region 11, and the etched region is the second doped 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 doped oxide layer 120, the inner wall surface and bottom surface of the groove 103, and the side surface of the first passivation contact layer 110 in the first doping region 11 and the second doping region 12, and a second doping film 155 located on the surface of the second dielectric film 154.

[0121] Referring to FIG. 14, the second dielectric film and the second doping film in the first doping region 11 and a portion of the second dielectric film and the second doping film located at the boundary between the first doping region 11 and the second doping region 12 are removed. This is because it is necessary to establish a leakage current path as shown in FIG. 1. Therefore, etching is not performed on the region where the leakage current path needs to be established, and a mask is formed thereon. The mask may include any one of ink, paraffin, or a doped silicate glass layer. The etching process may include any one of a dry etching process, a wet etching process, or a laser etching process.

[0122] In some embodiments, the exposed doped oxide film is also removed at the same time as the second dielectric film and the second doped film are removed, leaving the remaining second dielectric layer and second doped film partially as the connection layer 140 and partially as the 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, and the second passivation contact layer is formed before the connection layer is formed.

[0124] Continuing to refer to FIG. 5, a passivation layer 133 is formed to cover the first doped semiconductor layer 112, the second doped semiconductor layer 132, the connection layer 140, and the boundary between the first doped region 11 and the second doped region 12, and a first electrode 104 electrically connected to the first doped semiconductor layer 112 is formed, and a second electrode 105 electrically connected to the second doped semiconductor layer 132 is formed.

[0125] According to some embodiments of the present application, another aspect of the embodiments of the present application provides a stack cell, the stack cell including a bottom cell that 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 located on the side of the bottom cell away from the front electrode of the substrate.

[0126] In some embodiments, the stacked cells have first gridlines of a first polarity and second gridlines of a second polarity, where the first gridlines represent the first electrodes of the back-contact solar cells and the second gridlines represent the second electrodes of the back-contact solar cells.

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

[0128] The stack cell in the embodiment of the present application may be a two-layer solar cell, a three-layer solar cell, or a multi-layer stack solar cell having four or more layers.

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

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

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

[0132] The connecting members 318 electrically connect 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 members 318, and the connecting members 318 and the main grids / sub-grids of the back contact solar cells 30 are welded together.

[0133] In some embodiments, the connection member 318 and the sub-gate including the first electrode and the second electrode of the cell sheet are welded together, and in some embodiments, the connection member 318 and the primary grid of the cell sheet are welded together, and the primary grid includes a first primary grid welded to the first electrode and a second primary grid welded to the second electrode.

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

[0135] It should be noted that although there is a boundary between the first sealing film and the second sealing film before the lamination process, after the lamination process the photovoltaic assembly is formed and the concepts of the first sealing film and the second sealing film no longer exist, i.e. the first sealing film and the second sealing film already form an 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, the surface of the cover plate 32 facing the encapsulation film 31 may be textured to improve the utilization rate of incident light. The cover plate 32 may include a first cover plate and a second cover plate, where the first cover plate faces the first encapsulation film and the second cover plate faces the second encapsulation film, or the first cover plate faces one side of the back-contact solar cell and the second cover plate faces the other side of the back-contact solar cell.

[0137] Although the present application has been disclosed above using preferred embodiments, it is not intended to limit the scope of the claims. A person skilled in the art can make some possible changes and modifications without departing from the concept of the present application, so the scope of protection of the present application shall be equivalent to the scope limited by the claims. Furthermore, the examples and drawings shown in the present specification are merely illustrative and do not cover the entire scope of protection of the claims of the present application.

[0138] Those skilled in the art will understand that the above embodiments are specific examples for implementing the present application, and that various changes in form and details may be made in actual applications without departing from the spirit and scope of the present application. Those skilled in the art will be able to make any changes and modifications without departing from the spirit and scope of the present application, and 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 provided back to back, the first surface being provided with first doping regions and second doping regions arranged alternately in a first direction; a first passivation contact layer located in the first doping region; a doped oxide layer including a first portion disposed in the first passivation contact layer to be located in the first doped region, and a second portion extending from the first portion in the first direction to be located in the second doped region; a second passivation contact layer located in the second doping region, the second passivation contact layer having a doping type different from that of the first passivation contact layer; a connection layer located in a partial region of the first portion, surrounding a partial region of the second portion, electrically connected to the second passivation contact layer, extending along a side surface of the first passivation contact layer, and electrically connected to the first passivation contact layer; Including, Back contact solar cell.

2. The range of the length of the second portion in the first direction is 0 to 3 μm, the first direction is a direction from the second doping region to the first doping region; The back contact solar cell of claim 1 .

3. a first distance between the first doped region and the second surface is greater than a second distance between the second doped region and the second surface; the second doping region has a recess with respect 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 on the bottom of the groove; The back contact solar cell of claim 1 .

4. the difference between the first distance and the second distance is 5 μm or less; The back contact solar cell of claim 3 .

5. 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 portion faces the first portion, the fourth portion is positioned in the recessed groove so as to face the second portion, the second portion is located on a surface of the fourth portion; the connection layer is located on a side surface of the fourth portion and a bottom surface of the fourth portion remote from the second portion; The back contact solar cell of claim 3 .

6. a side surface of the fourth portion having an inwardly recessed portion; The connection layer is located inside the recess. The back contact solar cell of claim 5 .

7. 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 of claim 3 .

8. The material of the doped oxide layer includes borosilicate glass, phosphosilicate glass, borophosphosilicate glass, or fluorophosphate glass; The back contact solar cell of claim 1 .

9. the thickness of the connection layer is equal to or less than the thickness of the second passivation contact layer; The back contact solar cell of claim 1 .

10. the connection layer includes a first connection layer located in a partial region of the first portion, and a second connection layer surrounding a partial region of the second portion, electrically connected to the second passivation contact layer, and having a thickness equal to or less than that of the first connection layer; The back contact solar cell of claim 1 .

11. a region of the second connection layer that is connected to the second passivation contact layer is a first connection region; The remaining second connection layer is a second connection region having a thickness greater than that of the first connection region. The back contact solar cell of claim 10.

12. providing a substrate having first and second surfaces disposed back to back, the first surface having alternating first and second doped regions; forming a first passivation contact layer located in the first doped region; forming a doped oxide layer including a first portion located on a surface of the first passivation contact layer and a second portion extending along an edge of the first portion toward the second doped region so as to be located in the second doped region; forming a second passivation contact layer located in the second doped region, the second passivation contact layer having a doping type different from that of the first passivation contact layer; forming a connection layer located on a portion of the first portion, surrounding a portion of the second portion, electrically connected to the second passivation contact layer, and located on a side of the first passivation contact layer and electrically connected to the first passivation contact layer; A method for fabricating a back contact solar cell comprising:

13. The steps of forming the first passivation contact layer and forming the doped oxide layer include: forming a first dielectric layer, a first doping layer, and an oxide layer on the first surface of the substrate; removing a portion of the oxide film in the second doped region to expose a surface of the first doped film; removing the first dielectric film and the first doped film in the second doped region; In the step of forming the second passivation contact layer, the oxide film located in the first doping region is partially removed, and the remaining oxide film is used as a doped oxide film, and the remaining first dielectric film and the first doped film are used as the first passivation contact layer.

13. The method for making the back contact solar cell of claim 12.

14. The parameters of the process for removing the first doped film in the second doped region are: an etching solution is an alkaline solution, the concentration of the alkaline solution is 0.1 PPM to 0.6 PPM, the etching time is 20 seconds to 500 seconds, and the etching temperature is 50°C to 90°C; 14. The method of making the back contact solar cell of claim 13.

15. a cell string formed of a plurality of back contact solar cells according to any one of claims 1 to 11; a sealing film covering the surface of the cell string; a cover plate that covers a surface of the sealing film that is away from the cell string; a photovoltaic assembly including:

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