Back contact solar cell, preparation method thereof and photovoltaic module

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a back contact solar cell and a preparation method thereof, and a photovoltaic module, and the back contact solar cell comprises a substrate, and first doped regions and second doped regions which are arranged in a staggered manner; the first passivation contact layer is positioned in the first doped region; the second passivation contact layer is positioned in the second doped region; doped oxide layers, each doped oxide layer comprising a first portion and a second portion, the first portion being located on the surface of the first passivation contact layer; the second part is located on the second doped region; the connecting layer is located in a partial region of the first part, further surrounds a partial region of the second part and is electrically connected with the second passivation contact layer, and the connecting layer is located on the side face of the first passivation contact layer and is electrically connected with the first passivation contact layer. The back contact solar cell provided by the embodiment of the invention at least can improve the hot spot effect and increase the photoelectric conversion efficiency.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of photovoltaics, and particularly to a back-contact solar cell, a preparation method thereof, and a photovoltaic module. Background Art

[0002] The IBC cell (Interdigitated Back Contact) is a back-junction and back-contact solar cell structure in which positive and negative metal electrodes are arranged in an interdigitated manner on the backlight side of the cell, and its PN junction is located on the back of the cell. Among them, the back junction means that the PN junction is located on the back of the cell. The IBC cell is one of the photovoltaic cells with the highest conversion efficiency at present. This cell is based on single-crystalline silicon, and both the PN junction and the metal electrodes are located on the back of the cell, and there is no metal electrode shading on the front, so a very high short-circuit current and conversion efficiency can be obtained.

[0003] Photovoltaic modules composed of multiple cells are usually installed in open and sunny areas. During long-term use, it is inevitable to be covered by obstacles such as birds, dust, and fallen leaves. These obstacles form shadows on the solar cell modules, and inappropriate row spacing can also cause mutual shadows in a large solar cell module array. Due to the existence of local shadows, the current and voltage of some individual cells in the solar cell module change. As a result, the product of the local current and voltage of the solar cell module increases, thereby causing a local temperature rise on these cell modules. Defects in some individual cells in the photovoltaic module itself may also cause local heating during operation, and this phenomenon is called the "hot spot effect".

[0004] In the IBC cell, since both the P-type doped region and the N-type doped region are located on the back of the substrate and are completely isolated, during the process of forming a battery string from multiple IBC cells and then encapsulating them into a photovoltaic module, the hot spot effect may affect the power of the photovoltaic module and the safety problems caused by local temperature rise. Therefore, how to improve and solve the "hot spot effect" is an urgent problem for current technicians. Summary of the Invention

[0005] The embodiments of the present application provide a back-contact solar cell, a preparation method thereof, and a photovoltaic module, which are at least beneficial to improving the hot spot effect of the back-contact solar cell and increasing the photoelectric conversion efficiency.

[0006] According to some embodiments of the present application, on the one hand, an embodiment of the present application provides a back-contact solar cell, including: a substrate having a first surface and a second surface disposed opposite to each other, wherein a first doped region and a second doped region are arranged in an interleaved manner on the first surface; a first passivation contact layer located on the first doped region; a doped oxide layer, each doped oxide layer including a first portion and a second portion, the first portion being located on the surface of the first passivation contact layer; the second portion extending from the end of the first portion in the direction of the second doped region so that the second portion is located on the second doped region; a second passivation contact layer located on the second doped region, the doping type of the second passivation contact layer being different from the doping type of the first passivation contact layer; a connection layer located in a partial region of the first portion, the connection layer further surrounding a partial region of the second portion and being electrically connected to the second passivation contact layer, the connection layer being located on the side surface of the first passivation contact layer and being electrically connected to the first passivation contact layer.

[0007] In some embodiments, the length of the second portion in the first direction ranges from 0 to 3 μm, and the first direction refers to the direction in which the second doped region points to the first doped region.

[0008] In some embodiments, 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 first doped region has a groove relative to the second doped region, the second portion is located on the groove, the connection 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 less than or equal to 5 μm.

[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 is opposite to the first portion, the fourth portion is opposite to the second portion, the fourth portion is located on the groove, and the second portion is located on the surface of the fourth portion; the connection layer is located on the side surface 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 inward concave depression, and the connection layer is also located in the depression.

[0012] In some embodiments, the included 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 includes: borosilicate glass, phosphosilicate glass, borophosphosilicate glass, or fluorophosphosilicate 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 and a second connection layer. The first connection layer is located in a partial area of the first part, and the second connection layer surrounds a partial area of the second part and is electrically connected to the second passivation contact layer; the thickness of the second connection layer is less than or equal to the thickness of the first connection layer.

[0016] In some embodiments, the area where the second connection layer is connected to the second passivation contact layer is the first connection area, and the remaining second connection layer is the second connection area. The thickness of the first connection area is less than the thickness of the second connection area.

[0017] According to some embodiments of the present application, on the other hand, an embodiment of the present application provides a method for manufacturing a back-contact solar cell, including: providing a substrate having a first surface and a second surface arranged opposite to each other, and the first surface has a first doped region and a second doped region arranged alternately; forming a first passivation contact layer, the first passivation contact layer is located in the first doped region; forming a doped oxide layer, each doped oxide layer includes a first part and a second part, the first part is located on the surface of the first passivation contact layer; the second part extends along the end of the first part in the direction of the second doped region, so that the second part is located on the second doped region; forming a second passivation contact layer, the second passivation contact layer is located in the second doped region, and the doping type of the second passivation contact layer is different from the doping type of the first passivation contact layer; forming a connection layer, the connection layer is located in a partial area of the first part, and the connection layer also surrounds a partial area of the second part and is electrically connected to the second passivation contact layer, and the connection layer is located on the side surface of the first passivation contact layer and is electrically connected to the first passivation contact layer.

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

[0019] In some embodiments, the process parameters for removing the first doping film on the second doping region include: the etching solution is an alkaline solution, the concentration ratio in 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, on the other hand, an embodiment of the present application provides a photovoltaic module, including: a battery string composed of a plurality of back contact solar cells as described in any one of the above embodiments or back contact solar cells prepared by the preparation method of the back contact solar cells as described in any one of claims 12 to 14; an encapsulation adhesive film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulation adhesive film facing away from the battery string.

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

[0022] For the back contact solar cell provided by the embodiment of the present application, 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 respectively formed on the first doping region and the second doping region. Based on the chemical passivation and field passivation of the first passivation contact layer and the second passivation contact layer, the carrier recombination rate on the substrate surface can be reduced, thereby improving the photoelectric conversion efficiency of the back contact solar cell. Secondly, a connection layer is provided. The connection layer is located on the doped oxide layer and is electrically connected to the second passivation contact layer; for the connection layer located on the doped oxide layer, it is indirectly in contact with the first passivation contact layer through the doped oxide layer. Due to the characteristics of the dielectric film of the doped oxide layer itself and the small carrier mobility, the leakage channel formed by the connection layer through the doped oxide layer is limited, so the hot spot effect can be slightly improved, but the photoelectric conversion efficiency will not be reduced too much; the connection layer is also in contact with the side surface of the first passivation contact layer. In this way, the connection layer is directly in contact with the first passivation contact layer, and one end of the connection layer is also directly in contact with the second passivation contact layer, so a direct leakage channel can be formed, and the hot spot effect can be improved to a large extent. However, due to the limited contact area on the side surface and the limitation of the deposition process for the connection layer on the side surface, the thickness of the connection layer on the side surface will not be too large, so the leakage channel of this part will not be too large, and thus the photoelectric conversion efficiency will not be reduced too much. The hot spot effect is improved by two connection methods, namely, the indirect contact between the connection layer and the first passivation contact layer and the direct contact on the side surface, so as to ensure the yield of the finally formed photovoltaic module and the photoelectric conversion efficiency of the back contact solar cell itself.

[0023] Third, a doped oxide layer is provided on a part of the first passivation contact layer. The doped oxide layer can reduce the interfacial state charges on the surface of the first passivation contact layer, thereby improving the electric field distribution between the first passivation contact layer and the connection layer and between the first passivation contact layer and the substrate, avoiding the generation of large leakage currents and other adverse effects caused by the interfacial state charges. Secondly, the doped oxide layer is located on the surface of a part of the first passivation contact layer and extends onto the second doped region. Thus, a concave structure is formed among the doped oxide layer, the first passivation contact layer and the substrate. For the connection layer subsequently deposited on this film layer, due to the shielding of the doped oxide layer, the thickness of the formed connection layer is not greater than the thickness of the second passivation contact layer, thereby reducing the size of the leakage current path to ensure the balance of the leakage current and the battery efficiency. Description of the Drawings

[0024] One or more embodiments are exemplarily illustrated by the figures in the corresponding drawings. These exemplary illustrations do not limit the embodiments. Unless otherwise stated, the figures in the drawings do not constitute a proportional limitation. To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the following-described drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 A top view of a back-contact solar cell provided by an embodiment of the present application;

[0026] Figure 2 is Figure 1 A cross-sectional view along the A1-A2 section;

[0027] Figure 3 is Figure 2 A partial enlarged view at B in;

[0028] Figure 4 A partial enlarged view of a back-contact solar cell provided by an embodiment of the present application;

[0029] Figure 5 is Figure 1 Another cross-sectional view along the A1-A2 section;

[0030] Figure 6 A scanning electron microscope image of a back-contact solar cell provided by an embodiment of the present application;

[0031] Figure 7 A partial enlarged view of the first passivation contact structure and the substrate in a back-contact solar cell provided by an embodiment of the present application;

[0032] Figure 8 is Figure 7 a partial enlarged view of the first doped semiconductor layer in the first passivation contact structure in

[0033] Figures 9 to 14 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 in another embodiment of the present application;

[0034] Figure 15 a cross-sectional view of a photovoltaic module provided in yet another embodiment of the present application. Detailed Description of the Embodiment

[0035] As can be seen from the background art, current back-contact solar cells have the hot-spot effect and generally have a medium photoelectric conversion efficiency.

[0036] Embodiments of the present application provide a back-contact solar cell, a method for manufacturing the same, and a photovoltaic module. In the back-contact solar cell, by providing a doped oxide layer to improve the interfacial state charges between the first passivation contact layer and the connection layer and reduce the leakage current; providing the doped oxide layer on the second doped region to reduce the thickness of the connection layer; providing a connection layer, and making the connection layer indirectly and directly contact the first passivation contact layer, and the other end of the connection layer contact 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 finally formed photovoltaic module and the photoelectric conversion efficiency of the back-contact solar cell itself.

[0037] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order, or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present application, "a plurality of" means more than two, unless otherwise specifically defined.

[0038] Referring to "embodiments" herein means that a specific feature, structure, or characteristic described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0039] In the description of the embodiments of the present application, the term "and / or" is merely a description of the association relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent: the existence of A, the simultaneous existence of A and B, and the existence of B. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0040] In the description of the embodiments of the present application, the term "a plurality" means two or more (including two). Similarly, "a plurality of groups" means two or more groups (including two groups), and "a plurality of pieces" means two or more pieces (including two pieces).

[0041] In the description of the embodiments of the present application, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the embodiments of the present application.

[0042] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0043] In the corresponding drawings of the embodiments of the present application, for better understanding and convenience of description, the thickness and area of the layer are enlarged. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component between the two components. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on a partial edge of the entire surface.

[0044] In the description of the embodiments of the present application, when a certain component "includes" another component, unless otherwise stated, other components are not excluded, and other components may further be included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on / located on" another component, it may be "directly on" the other component (i.e., located on the surface of the other component with no other components therebetween), or there may be other components therebetween. In addition, 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 no other components are located therebetween.

[0045] The terms used in the description of the various embodiments herein are only for the purpose of describing specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the part" is also intended to include the plural form unless the context clearly indicates otherwise. Among them, the components include components such as layers, films, regions, or plates.

[0046] The embodiments of the present application will be described in detail below with reference to the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present application, many technical details are presented for the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0047] Figure 1 A top view of a back-contact solar cell provided in an embodiment of the present application; Figure 2 is Figure 1 a cross-sectional view along the A1-A2 section; Figure 3 is Figure 2 a partial enlarged view at B in

[0048] Reference Figures 1 to 3, according to some embodiments of the present application, on the one hand, an embodiment of the present application provides a back-contact solar cell, including: a substrate 100 having a first surface 101 and a second surface 102 disposed opposite to each other, with a first doping region 11 and a second doping region 12 arranged in an interleaved manner on the first surface 101; a first passivation contact layer 110 located on the first doping region 11; a doped oxide layer 120, each doped oxide layer 120 including a first portion 121 and a second portion 122, the first portion 121 being located on the surface of the first passivation contact layer 110; the second portion 122 extending from the end of the first portion 121 in the direction of the second doping region 12 such that the second portion 122 is located on the second doping region 12; a second passivation contact layer 130 located on the second doping region 12, the doping type of the second passivation contact layer 130 being different from that of the first passivation contact layer 110; a connection layer 140 located in a partial region of the first portion 121, the connection layer 140 further surrounding a partial region of the second portion 122 and being electrically connected to the second passivation contact layer 130, the connection layer 140 being located on the side surface of the first passivation contact layer 110 and being electrically connected to the first passivation contact layer 110.

[0049] The back-contact solar cell provided by the embodiment of the present application is provided with a first doping region 11 and a second doping region 12 on a substrate 100, and a first passivation contact layer 110 and a second passivation contact layer 130 are respectively formed on the first doping region 11 and the second doping region 12. Based on the chemical passivation and field passivation of the first passivation contact layer 110 and the second passivation contact layer 130, the carrier recombination rate on the surface of the substrate can be reduced, thereby improving the photoelectric conversion efficiency of the back-contact solar cell. Secondly, a connection layer 140 is provided. The connection layer 140 is located on the doped oxide layer 120 and is electrically connected to the second passivation contact layer 130. For the connection layer 140 located on the doped oxide layer 120, it is indirectly in contact with the first passivation contact layer 110 through the doped oxide layer 120. Due to the characteristics of the dielectric film of the doped oxide layer 120 itself and the small carrier mobility, the leakage current path formed by the connection layer 140 through the doped oxide layer 120 is limited, so that the hot spot effect can be slightly improved, but the photoelectric conversion efficiency will not be reduced too much. The connection layer 140 is also in contact with the side surface of the first passivation contact layer 110. In this way, the connection layer 140 is in direct contact with the first passivation contact layer 110, and one end of the connection layer 140 is also in direct contact with the second passivation contact layer 130, so that a direct leakage current path can be formed, and the hot spot effect can be improved to a large extent. However, due to the limited contact area on the side surface and the limitation of the deposition process for the connection layer 140 located on the side surface, the thickness of the connection layer 140 located on the side surface will not be too large, so that the leakage current path of this part will not be too large, and thus the photoelectric conversion efficiency will not be reduced too much. By using two connection methods, namely, the indirect contact between the connection layer 140 and the first passivation contact layer 110 and the direct contact on the side surface, the hot spot effect is improved, so that the yield of the finally formed photovoltaic module and the photoelectric conversion efficiency of the back-contact solar cell itself can be ensured.

[0050] Thirdly, a doped oxide layer 120 is provided on a part of the first passivation contact layer 110. The doped oxide layer 120 can reduce the interface state charges 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 connection layer 140 and between the first passivation contact layer 110 and the substrate, and avoiding the generation of large leakage current and other adverse effects caused by the interface state charges. Secondly, the doped oxide layer 120 is located on the surface of a part of the first passivation contact layer 110 and extends to the second doping region 12. In this way, an inward concave structure is formed among the doped oxide layer 120, the first passivation contact layer 110 and the substrate. For the connection layer 140 deposited on this film layer later, due to the shielding of the doped oxide layer 120, the thickness of the formed connection layer 140 is not greater than the thickness of the second passivation contact layer 130, thereby reducing the size of the leakage current path to ensure the balance of the leakage current and the battery efficiency.

[0051] In some embodiments, the material of the substrate 100 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. Among them, the elemental semiconductor material may be in single crystal state, polycrystalline state, amorphous state or microcrystalline state (the state with both single crystal state and amorphous state is called microcrystalline state). For example, silicon may be at least one of single crystal silicon, polycrystalline silicon, amorphous silicon or microcrystalline silicon.

[0052] In some embodiments, the material of the substrate 100 may also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanide, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, copper indium selenide and other materials. The substrate 100 may also be a sapphire substrate, a silicon-on-insulator substrate or a germanium-on-insulator substrate.

[0053] 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, and the N-type doping element 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, and the P-type doping element may be any one of group III elements such as boron (B), aluminum (Al), gallium (Ga) or indium (In).

[0054] In some embodiments, the first surface 101 is the back surface and the second surface 102 is the front surface. Among them, the "front" and "back" in the front surface and the back surface are relative, that is, "front" refers to the surface facing the sunlight along the vertical direction, and "back" refers to the surface facing away from the sunlight along the vertical direction.

[0055] In some embodiments, the back-contact solar cell is a single-sided cell, and the front surface can be used as the light-receiving surface for receiving incident light, and the back surface is used as the backlight surface. Among them, the backlight surface can also receive incident light, but the efficiency of receiving incident light is weaker than that of the light-receiving surface.

[0056] In some embodiments, the back-contact solar cell is a double-sided cell, that is, both the front surface and the back surface of the substrate can be used as light-receiving surfaces and can be used to receive incident light.

[0057] In some embodiments, the first doping region 11 refers to the region where the positive projection of the first electrode 104 on the reference plane is located, and the first doping region 11 serves as the functional region for forming the first type of metal electrode; similarly, the second doping region 12 refers to the region where the positive projection of the second electrode 105 on the reference plane is located, and the second doping region 12 serves as the functional region for forming the second type of metal electrode.

[0058] In some embodiments, there is a spacer region (also a non-metal electrode region) between the first doped region 11 and the second doped region 12. The spacer region refers to the region where the positive projections of the first electrode 104 and the second electrode 105 on the reference plane do not overlap, that is, the spacer region serves as a functional region where no metal electrode is formed. In other embodiments, there is no spacer region between the first doped region 11 and the second doped region 12, and there is a height difference between the first doped region 11 and the second doped region 12. The film layers located on the first doped region 11 and the second doped region 12 do not contact each other.

[0059] It should be noted that to ensure that the film layers contacted by the first electrode 104 and the second electrode 105 are both corresponding functional film layers, the range of the first doped region 11 is greater than or equal to the range of the positive projection of the first electrode 104 on the reference plane, that is, any positive projection of the first electrode 104 on the reference plane is located within the first doped region 11, and the distance between the edge of the first doped region 11 and the edge of the positive projection pattern is greater than or equal to 0. Similarly, the range of the second doped region 12 is greater than or equal to the range of the positive projection of the second electrode 105 on the reference plane. The reference plane is a flat plane perpendicular to the thickness direction Z of the substrate 100. The reference plane is parallel to the surface formed by the second direction X and the first direction Y.

[0060] In addition, the first doped region 11, the second doped region 12, and the spacer region are regions set for functional partitioning of the substrate 100 (or the first surface 101) to illustrate the distribution of each film layer structure of the back-contact solar cell. All three actually belong to the substrate 100 (or the first surface 101), and there is no boundary distinction between different regions. Only the film layers located on them may be different. For example, a first passivation contact layer 110 is provided on the first doped region 11, a second passivation contact layer 130 is provided on the second doped region 12, and a passivation layer is provided on most of the spacer region and a connection layer 140 is provided in some regions.

[0061] 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.

[0062] In some embodiments, the first distance between the first doped region 11 and the second surface 102 is greater than the second distance between the second doped region 12 and the second surface 102; the first doped region 11 has a groove 103 relative to the second doped region 12, the second part 122 is located on the groove 103, the connection 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.

[0063] In some embodiments, refer to Figure 2, the difference between the first distance and the second distance is less than or equal to 5 μm, that is, the depth h of the groove 103 is less than or equal to 5 μm. Thus, the first surface 101 of the substrate 100 is a rough surface with a concavo-convex structure. Based on the limitation of the groove 103, the refractive index of the incident light can be increased, thereby improving the photoelectric conversion efficiency of the back-contact solar cell. Secondly, since the height difference between the first doping region 11 and the second doping region 12 is less than or equal to 5 μm, and the thickness of the second passivation contact layer 130 formed on the second doping region 12 is usually less than 2 μm, thus, based on the height difference between the first doping region 11 and the second doping region 12 itself, the function of the spacer region can be realized, so that there is no need to additionally provide a spacer region, thereby increasing the area of carrier collection, and thus improving the photoelectric conversion efficiency of the carrier.

[0064] Furthermore, the depth h of the groove 103 ranges from 0.5 μm to 1.5 μm. When the depth h of the groove 103 is within this range, the depth of etching the substrate 100 can be controlled. On the premise of ensuring that the first passivation contact layer 110 on the second doping region 12 is completely etched, the substrate 100 can be etched less, avoiding the adverse effects caused by excessive etching of the substrate 100; secondly, the time for etching the substrate 100 and the amount of etching solution can also be reduced, reducing the preparation cost.

[0065] Specifically, the depth h of the groove 103 can 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.

[0066] In some embodiments, the included 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 increasing the internal reflectivity of the incident light. The inclined inclined surface at least makes the thickness of the connecting layer 140 located thereon less than or equal to the thickness of the connecting layer 140 in other regions, thereby reducing the size of the leakage channel.

[0067] The included angle β between the bottom surface of the groove 103 and the side surface of the groove 103 can be 110°, 115°, 120°, 125°, 130°, 135°, 140°, 145° or 150°.

[0068] 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 on 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.

[0069] The first doped semiconductor layer 112 can form a band bending on the surface of the substrate 100. The first tunneling dielectric layer 111 causes an asymmetric shift in the energy band on the surface of the substrate 100, such that the potential barrier for majority carriers (also known as majority charge carriers) in the carriers is lower than the potential barrier for minority carriers (also known as minority charge carriers). Therefore, the majority carriers can more easily perform quantum tunneling through the first tunneling dielectric layer 111, while the minority carriers are difficult to pass through the first tunneling dielectric layer 111, so as to achieve selective transport of carriers.

[0070] In addition, the first tunneling dielectric layer 111 has a chemical passivation effect. Specifically, due to the presence of interface state defects at the interface between the substrate 100 and the first tunneling dielectric layer 111, the interface state density of the first surface 101 is relatively large. The increase in the interface state density promotes the recombination of photo-generated carriers, increases the fill factor, short-circuit current, and open-circuit voltage of the back-contact solar cell, so as to improve the photoelectric conversion efficiency of the back-contact solar cell. Setting the first tunneling dielectric layer 111 on the first surface 101 enables the first tunneling dielectric layer 111 to have a chemical passivation effect on the surface of the substrate 100, specifically: by saturating the dangling bonds of the substrate 100, reducing the defect state density of the substrate 100, and reducing the recombination centers of the substrate 100 to reduce the carrier recombination rate.

[0071] The first doped semiconductor layer 112 has a field passivation effect. Specifically, an electrostatic field pointing into the substrate 100 is formed on the surface of the substrate 100, causing the minority carriers to escape from the interface, thereby reducing the minority carrier concentration, reducing the carrier recombination rate at the interface of the substrate 100, and thus increasing the open-circuit voltage, short-circuit current, and fill factor of the back-contact solar cell, and enhancing the photoelectric conversion efficiency of the back-contact solar cell.

[0072] 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. When the first tunneling dielectric layer 111 is within any of the above ranges, the thickness of the first tunneling dielectric layer 111 is relatively thin, and the majority carriers can more easily perform quantum tunneling through the first tunneling dielectric layer 111, while the minority carriers are difficult to pass through the first tunneling dielectric layer 111, so as to achieve selective transport of carriers.

[0073] 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.

[0074] In some embodiments, the first doped semiconductor layer 112 includes at least one of a doped amorphous silicon layer, a doped polysilicon layer, a doped microcrystalline silicon layer, a doped silicon carbide layer, or a doped single-crystalline silicon layer.

[0075] 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 on the second region, the second doped 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 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.

[0076] Among them, the function, material, and thickness setting of the second tunneling dielectric layer 131 can refer to the description of the above-mentioned first tunneling dielectric layer 111; the function and material setting of the second doped semiconductor layer 132 can refer to the description of the above-mentioned first doped semiconductor layer 112.

[0077] 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; the second doped semiconductor layer 132 is the other of an N-type doped layer or a P-type doped layer.

[0078] In some embodiments, the doping element in the first doped semiconductor layer 112 has the same conductivity type as the doping element in the substrate 100. For example, the substrate 100 has an N-type doping element, and the first doped semiconductor layer 112 has an N-type doping element; or the substrate 100 has a P-type doping element, and the first doped semiconductor layer 112 has a P-type doping element. In this way, the doping elements between the first doped semiconductor layer 112 and the substrate 100 are of the same conductivity type. By setting the concentration of the doping element in the first doped semiconductor layer 112 to be 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 the built-in electric field constructed by the high-low junction, carriers can quickly migrate from the substrate 100 to the first doped semiconductor layer 112 and then be collected by the first electrode 104.

[0079] Correspondingly, the doping element in the second doped semiconductor layer 132 has a different conductivity type from the doping element of the substrate 100. For example, the substrate 100 has an N-type doping element, and the second doped semiconductor layer 132 has a P-type doping element; or the substrate 100 has a P-type doping element, and the second doped semiconductor layer 132 has an N-type doping element. Thus, a PN junction is formed between the substrate 100 and the second doped semiconductor layer 132, and minority carriers and majority carriers flow to the corresponding P region and N region under their respective acting forces, which is beneficial to accelerating the mobility of carriers.

[0080] In some other embodiments, the above situation presents an opposite state. For example, the doping element in the first doped semiconductor layer 112 has a different conductivity type from the doping element of the substrate 100, and the doping element in the second doped semiconductor layer 132 has the same conductivity type as the doping element of the substrate 100, which will not be elaborated in detail here.

[0081] The doped oxide layer 120 can reduce the interface state charges 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 connection layer 140 and between the first passivation contact layer 110 and the substrate 100, and avoiding the generation of large leakage currents and other adverse effects caused by interface state charges. Secondly, the doped oxide layer 120 is located on the surface of a part of the first passivation contact layer 110 and extends to the second doped region 12. Thus, an inward concave structure is formed among the doped oxide layer 120, the first passivation contact layer 110 and the substrate 100. For the connection layer 140 deposited on this film layer subsequently, due to the shielding of the doped oxide layer 120, the thickness of the formed connection layer 140 is not greater than the thickness of the second passivation contact layer 130, thereby reducing the size of the leakage current path to ensure the balance of leakage current and battery efficiency.

[0082] In some embodiments, the material of the doped oxide layer 120 includes: borosilicate glass, phosphosilicate glass, borophosphosilicate glass or fluorophosphosilicate glass.

[0083] In some embodiments, the thickness of the doped oxide layer 120 is 0 - 120 nm. Further, the thickness of the doped oxide layer 120 is 10 nm - 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.

[0084] In some embodiments, the doped oxide layer 120 has a doping element, and the doping element can be the first doping element of the first doped semiconductor layer 112. This doping element can serve as a carrier, so that the connection layer 140 and the first doped semiconductor layer 112 can form an electrical connection through this doping element to improve the effect of leakage current.

[0085] In some embodiments, the doped oxide layer 120 has doping elements, and the doping elements may be the first doping element of the first doped semiconductor layer 112 and the second doping element of the second doped semiconductor layer 132, and the doping concentration of the first doping element is greater than that of the second doping element. In this way, by adjusting the ratio of the doping concentration of the first doping element to that of the second doping element, the ability of the doped oxide layer 120 to composite interface state charges can be improved, thereby controlling the leakage current. Secondly, controlling the concentration ratio relationship between the first doping element and the second doping element can change the performance of the doped oxide layer 120 itself. At least, it can make the doped oxide layer 120 have stronger fluidity, thereby reducing the defects of the first doped semiconductor layer 112 and improving the flatness of the first doped semiconductor layer 112; at least, it can weaken the decomposition ability of the doped oxide layer 120, so that it will not decompose into acid when absorbing sodium ions later, affecting the photoelectric conversion efficiency of the back-contact solar cell.

[0086] In some embodiments, the length of the second part 122 in the first direction ranges from 0 to 3 μm, and the first direction Y refers to the direction in which the second doped region 12 points to the first doped region 11. The length of the second part 122 can also ensure that the thickness of the connecting layer 140 located on the side surface 1120 is not too thin, so as to establish a leakage channel, thereby reducing the hot spot effect. However, due to the shielding of the second part 122, the thickness of the connecting layer 140 will not be too large, and the size of the leakage channel is also limited, so that not many electrons and holes will recombine, and thus the photoelectric conversion efficiency will not be greatly reduced. Among them, the length of the second part 122 in the first direction can be 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm.

[0087] In some embodiments, the doped oxide layer 120 is only located in part of the first doped region 11, and the doped oxide layer 120 is not located between the first electrode 104 and the first doped semiconductor layer 112, so as to avoid increasing the contact resistance between the first electrode 104 and the first doped semiconductor layer 112 due to the dielectric film characteristics of the doped oxide layer 120. Among them, the above-mentioned part of the first doped region 11 refers to a part of the number of the first doped regions 11 and a part of the region of the first doped region 11.

[0088] Figure 4 This is a partial enlarged view of a back-contact solar cell provided by an embodiment of the present application.

[0089] Reference Figure 4, in some embodiments, the first passivation contact layer 110 is doped with a P-type doping element. The first passivation contact layer 110 includes a continuous third portion 1121 and a fourth portion 1122. The third portion 1121 is opposite to the first portion 121, and the fourth portion 1122 is opposite to the second portion 122. The fourth portion 1122 is located on the groove 103, and the second portion 122 is located on the surface of the fourth portion 1122; the connection layer 140 is located on the side surface of the fourth portion 1122 and 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. Based on the structure of the first passivation contact layer 110, a light trapping structure is formed between the first passivation contact layer 110 and the substrate 100 to increase internal reflection.

[0090] The connection layer 140 is located on the doped oxide layer 120 and is electrically connected to the second passivation contact layer 130; for the connection layer 140 located on the doped oxide layer 120, it is indirectly in contact with the first passivation contact layer 110 through the doped oxide layer 120. Due to the characteristics of the dielectric film of the doped oxide layer 120 itself and the small carrier mobility, the leakage current channel formed by the connection layer 140 through the doped oxide layer 120 is limited. Thus, the hot spot effect can be slightly improved, but the photoelectric conversion efficiency will not be reduced significantly; the connection layer 140 is also in contact with the side surface 1120 of the first passivation contact layer 110. In this way, the connection layer 140 is directly in contact with the first passivation contact layer 110, and one end of the connection layer 140 is also directly in contact with the second passivation contact layer 130. Thus, a direct leakage current channel can be formed, and the hot spot effect can be improved to a large extent. However, due to the limited contact area of the side surface 1120 and the limitation of the deposition process for the connection layer 140 located on the side surface, the thickness of the connection layer 140 located on the side surface will not be too large. Thus, the leakage current channel of this part will not be too large, and the photoelectric conversion efficiency will not be reduced too much. By the two connection methods of the indirect contact between the connection layer 140 and the first passivation contact layer 110 and the direct contact located on the side surface 1120 to improve the hot spot effect, the yield of the finally formed photovoltaic module and the photoelectric conversion efficiency of the back-contact solar cell itself can be ensured.

[0091] In some embodiments, the connection layer 140 is in contact with the top surface 123, the side surface 124, and the bottom surface 125 of the doped oxide layer 120.

[0092] In some embodiments, the material of the connection layer 140 can be any conductive material layer, such as a metal layer, a doped semiconductor layer, a transparent conductive layer, or a metal nitride.

[0093] In some embodiments, the thickness of the connection layer 140 is 80 nm to 240 nm. Further, the thickness of the connection layer 140 is 100 nm to 200 nm. The thickness of the connection layer 140 is 80 nm, 100 nm, 130 nm, 150 nm, 180 nm, 210 nm, or 240 nm.

[0094] In some embodiments, the thickness of the connection layer 140 is less than or equal to the thickness of the second passivation contact layer 130. Thus, by setting the thickness of the connection layer 140 to be small, the size of the connection layer 140 as a leakage channel is small, and the leakage area is small, so that the number of electron-hole recombinations can be reduced, and the photoelectric conversion efficiency can be improved.

[0095] Figure 5 For Figure 1 Another cross-sectional view along the A1-A2 section.

[0096] In some embodiments, referring to Figure 5 , the material of the connection layer 140 is the same as that of the second passivation contact layer 130, and they are the same continuous film layer. The connection layer 140 includes a stacked third tunneling dielectric layer 141 and a third doped semiconductor layer 142. The material of the third tunneling dielectric layer 141 is the same as that of the second tunneling dielectric layer 131, and the material of the third doped semiconductor layer 142 is the same as that of the second doped semiconductor layer 132. 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 doped semiconductor layer 142 is less than or equal to the thickness of the second doped semiconductor layer 132.

[0097] Figure 6 This is a scanning electron micrograph of a back-contact solar cell provided by an embodiment of the present application.

[0098] In some embodiments, referring to Figure 6 , the connection layer 140 includes a first connection layer 143 and a second connection layer 144. The first connection layer 143 is located in a partial area of the first part 121, and the second connection layer 144 surrounds a partial area of the second part 122 and is electrically connected to the second passivation contact layer 130; the thickness of the second connection layer 144 is less than or equal to the thickness of the first connection layer 143.

[0099] In some embodiments, referring to Figure 6 , the area where the second connection layer 144 is connected to the second passivation contact layer 130 is the first connection area 1442, and the remaining second connection layer 140 is the second connection area 1441. The thickness of the first connection area 1442 is less than the thickness of the second connection area 1441. By controlling the thicknesses of the connection layer 140 and the second passivation contact layer 130, the area of the leakage channel is reduced, and thus the leakage current is controlled.

[0100] Figure 7 A partial enlarged view of a first passivation contact structure and a substrate 100 in a back-contact solar cell provided by an embodiment of the present application; Figure 8 is Figure 7 A partial enlarged view of a first doped semiconductor layer 112 in the first passivation contact structure in

[0101] In some embodiments, referring to Figure 7 and Figure 8 , the side surface of the fourth part 1122 (refer to Figure 4 ) has an inwardly concave depression 160, and the connection layer 140 is also located within the depression 160.

[0102] In some embodiments, continuing to refer to Figure 2 , the back-contact solar cell further includes: a passivation layer 133, and the passivation layer 133 covers the first passivation contact layer 110, the connection layer 140, and the second passivation contact layer 130.

[0103] In some embodiments, the passivation layer 133 can be a single-layer structure or a stacked-layer structure, and the material of the passivation layer 133 can be one or more of materials such as silicon oxide, silicon nitride, silicon oxynitride, carbon oxynitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0104] In some embodiments, the back-contact solar cell further includes an antireflection layer, and the antireflection layer is located on the surface of the passivation layer. The antireflection layer is used to reduce or eliminate the reflected light on the surface of the back-contact solar cell, thereby increasing the light transmittance on the surface of the back-contact solar cell and reducing or eliminating the stray light of the system. The material of the antireflection layer includes silicon nitride or silicon oxynitride.

[0105] It should be noted that Figure 6 , the scanning electron microscope image in

[0106] shows that the back-contact solar cell includes a passivation layer and an antireflection layer located on the passivation layer, but the antireflection layer is not marked. Secondly, the boundaries between the respective film layers are schematically shown by dashed lines.

[0107] In some embodiments, the second surface 102 has a textured surface structure (not shown), and the textured surface structure includes a plurality of pyramid structures. The back-contact solar cell further includes a front passivation layer 106, and the front passivation layer 106 covers the textured surface structure 114.

[0108] In some embodiments, the material of the front passivation layer 106 is the same as the material of the passivation layer 133, and the front passivation layer 106 and the passivation layer 133 are prepared by the same preparation process.

[0109] Continue to refer to Figure 2 , the back-contact solar cell includes: a first electrode 104, and the first electrode 104 is in electrical contact with the first doped semiconductor layer 112.

[0110] Continue to refer to Figure 2 , the back-contact solar cell includes: a second electrode 105, and the second electrode 105 is in electrical contact with the second doped semiconductor layer 132.

[0111] In some embodiments, either the first electrode 104 or the second electrode 105 can be sintered from a burn-through type metal paste or an LECO (Laser-enhanced contact optimization) paste. The metal paste and the LECO paste can include at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0112] In some embodiments, the back surface can have a concavo-convex structure, that is, at least one of the first doped region 11, the second doped region 12, and the spacer region can have a concavo-convex structure. The concavo-convex structure can increase the internal reflection of incident light, thereby improving the utilization rate of incident light, and further improving the cell efficiency of the back-contact solar cell.

[0113] It should be noted that Figure 2 and Figure 5 the shown first electrode 104 penetrates through the passivation layer and is in electrical contact with the first doped semiconductor layer 112, and the second electrode 105 penetrates through the passivation layer and is in electrical contact with the second doped semiconductor layer 132 are only examples. In an actual back-contact solar cell, the connection relationship between the first electrode 104 and the first doped semiconductor layer 112 can be a contact connection or an indirect connection through conductive particles; the connection relationship between the second electrode 105 and the second doped semiconductor layer 132 can be a contact connection or an indirect connection through conductive particles. The conductive particles can be silver crystals, silver aggregates, silver particles, or other metal particles with conductivity.

[0114] The back-contact solar cell provided by the embodiment of the present application is provided with a first doping region 11 and a second doping region 12 on a substrate 100, and a first passivation contact layer 110 and a second passivation contact layer 130 are respectively formed on the first doping region 11 and the second doping region 12. Based on the chemical passivation and field passivation of the first passivation contact layer 110 and the second passivation contact layer 130, the carrier recombination rate on the surface of the substrate 100 can be reduced, thereby improving the photoelectric conversion efficiency of the back-contact solar cell. Secondly, a connection layer 140 is provided. The connection layer 140 is located on the doped oxide layer 120 and is electrically connected to the second passivation contact layer 130. For the connection layer 140 located on the doped oxide layer 120, it is indirectly in contact with the first passivation contact layer 110 through the doped oxide layer 120. Due to the characteristics of the dielectric film of the doped oxide layer 120 itself and the small carrier mobility, the leakage current path formed by the connection layer 140 through the doped oxide layer 120 is limited, so that the hot spot effect can be slightly improved, but the photoelectric conversion efficiency will not be reduced too much. The connection layer 140 is also in contact with the side surface of the first passivation contact layer 110. In this way, the connection layer 140 is directly in contact with the first passivation contact layer 110, and one end of the connection layer 140 is also directly in contact with the second passivation contact layer 130, so that a direct leakage current path can be formed, and the hot spot effect can be improved to a large extent. However, due to the limited contact area on the side surface, and due to the deposition process limitations, the thickness of the connection layer 140 on the side surface will not be too large, so that the leakage current path of this part will not be too large, and thus the photoelectric conversion efficiency will not be reduced too much. By the two connection methods of the indirect contact between the connection layer 140 and the first passivation contact layer 110 and the direct contact on the side surface to improve the hot spot effect, the yield of the finally formed photovoltaic module and the photoelectric conversion efficiency of the back-contact solar cell itself can be ensured.

[0115] Thirdly, a doped oxide layer 120 is provided on a part of the first passivation contact layer 110. The doped oxide layer 120 can reduce the interface state charges 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 connection layer 140 and between the first passivation contact layer 110 and the substrate 100, and avoiding the generation of large leakage currents and other adverse effects caused by the interface state charges. Secondly, the doped oxide layer 120 is located on the surface of a part of the first passivation contact layer 110 and extends to the second doping region 12. In this way, an inward concave structure is formed among the doped oxide layer 120, the first passivation contact layer 110 and the substrate 100. For the connection layer 140 deposited on this film layer later, due to the shielding of the doped oxide layer 120, the thickness of the formed connection layer 140 is not greater than the thickness of the second passivation contact layer 130, thereby reducing the size of the leakage current path to ensure the balance between the leakage current and the battery efficiency.

[0116] Correspondingly, according to some embodiments of the present application, on the other hand, an embodiment of the present application provides a method for manufacturing a back-contact solar cell for manufacturing the solar cell provided in the above embodiments. The same or corresponding technical features as those in the above embodiments will not be described in detail herein.

[0117] Figures 9 to 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 in another embodiment of the present application.

[0118] It should be noted that Figures 9 to 14 a method for manufacturing a back-contact solar cell with a film layer connected by a connection layer 140 and a second passivation contact layer 130 is taken as an example. Figure 1 Different manufacturing methods will be described in another embodiment below. For the parts not elaborated, the manufacturing methods are the same or similar.

[0119] Referring to Figures 9 to 14 , the manufacturing method includes: providing a substrate 100, the substrate 100 having a first surface 101 and a second surface 102 arranged opposite to each other, the first surface 101 having a first doping region 11 and a second doping region 12 arranged in an interleaved manner; forming a first passivation contact layer 110, the first passivation contact layer 110 being located in the first doping region 11; forming a doped oxide layer 120, each doped oxide layer 120 including a first portion 121 and a second portion 122, the first portion 121 being located on the surface of the first passivation contact layer 110; the second portion 122 extending in the direction of the second doping region 12 along the end of the first portion 121, so that the second portion 122 is located on the second doping region 12; forming a second passivation contact layer 130, the second passivation contact layer 130 being located in the second doping region 12, the doping type of the second passivation contact layer 130 being different from the doping type of the first passivation contact layer 110; forming a connection layer 140, the connection layer 140 being located in a partial region of the first portion 121, the connection layer 140 further surrounding a partial region of the second portion 122 and being electrically connected to the second passivation contact layer 130, the connection layer 140 being located on the side surface of the first passivation contact layer 110 and being electrically connected to the first passivation contact layer 110.

[0120] Referring to Figure 9 , the manufacturing method includes: providing a substrate 100, the substrate 100 having a first surface 101 and a second surface 102 arranged opposite to each other, the first surface 101 having an alternately arranged first treatment region and a second treatment region. The areas of the first treatment region and the second treatment region are different from the areas of the first doping region 11 and the second doping region 12 formed subsequently.

[0121] The first surface 101 and the second surface 102 of the substrate 100 are polished flat surfaces. Texturing treatment is performed on the second surface 102. The texturing treatment includes: chemical etching. For example, a mixed solution of potassium hydroxide and hydrogen peroxide solution can be used to clean the original substrate 100. Specifically, the surface texture structure that meets the expected morphology can be formed by controlling the concentration ratio of potassium hydroxide and hydrogen peroxide solution. In some embodiments, methods such as laser etching, mechanical method, or plasma etching can also be used to form the surface texture structure. In laser etching, the laser process parameters are controlled to obtain the surface texture structure that meets the expected morphology. Among them, the surface texture structure includes a plurality of pyramid structures.

[0122] Reference Figures 10 to 12 , the process steps of forming the first passivation contact layer 110 and forming the doped oxide layer 120 include: forming a first dielectric film, a first doped film, and an oxide film on the first surface 101 of the substrate 100; removing the oxide film on the upper part of the second doped region 12 to expose the surface of the first doped film; removing the first dielectric film and the first doped film on the second doped region 12; removing part of the oxide film located in the first doped region 11 during the formation of the second passivation contact layer 130, and the remaining oxide film serves as the doped oxide layer, and the remaining first dielectric film and the first doped film together serve as the first passivation contact layer 110.

[0123] In some embodiments, a first processing region 21 and a second processing region 22 are provided on the substrate 100.

[0124] Specifically, reference Figure 10 , the preparation method includes: forming a first dielectric film 151, a first doped film 152, and an oxide film 153 on the first processing region 21 and the second processing region 22.

[0125] In one example, the process steps of forming the first dielectric film 151, the first doped film 152, and the oxide film include: forming the first dielectric film 151 on the first processing region 21 and the second processing region 22 of the substrate 100 through chemical vapor deposition process; forming a first amorphous silicon layer on the first dielectric film 151 through PECVD process; forming a doped source layer on the surface of the first amorphous silicon layer by PECVD process; through doping process, part of the doping elements in the doped source layer migrate to the first amorphous silicon layer, and the first amorphous silicon layer crystallizes to form the first doped film 152, and the doped source layer is converted into the oxide film 153. In some embodiments, a thinning process is also involved in the formed oxide film 153 to reduce the thickness of the oxide film 153.

[0126] Reference Figure 11 , patternwise removing the oxide film 153 in the second processing region 22. The process of removing the oxide film 153 can be laser etching or wet etching process.

[0127] ReferenceFigure 12 The process parameters for removing the first doping film 152 on the second doping region 12, that is, removing the first doping film 152 in the second processing region 22, include: the etching solution is an alkaline solution, the concentration ratio in the alkaline solution is 0.1 PPM (volume ratio 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.

[0128] When removing the first doping film 152 on the second doping region 12, the substrate 100 will also be continuously etched, thereby forming a groove 103.

[0129] Among them, with reference to Figure 12 and Figure 13 , during the etching process, since the etching solution is also corrosive to the first doping film 152 and the etching is isotropic, back-etching is caused to part of the substrate 100 located in the first processing region 21 and below the oxide film and the first doping film 152, thereby forming a concave structure. The region of the unetched end 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.

[0130] Reference Figure 13 , the process steps for forming the second passivation contact layer 130 include: forming a second dielectric film 154 and a second doping film 155 on the first doping region 11 and the second doping region 12. The second dielectric film 154 is located on the surface of the doped oxide layer 120, the inner wall surface and the bottom surface of the groove 103, and the side surface of the first passivation contact layer 110; the second doping film 155 is located on the surface of the second dielectric film 154.

[0131] Reference Figure 14 , removing the second dielectric film and the second doping film on the first doping region 11 and part of the second dielectric film and the second doping film at the junction of the first doping region 11 and the second doping region 12. Among them, the above part is due to the need to establish a partial leakage channel as shown in Figure 1 . A mask will be formed on the region where the leakage channel needs to be established without etching. The mask can include any one of ink, paraffin, or a doped silicon glass layer. The etching process can include any one of a dry etching process, a wet etching process, or a laser etching process.

[0132] In some embodiments, when removing the second dielectric film and the second doping film, the exposed doped oxide film is also removed. The remaining part of the second dielectric layer and the second doping film serves as the connection layer 140 and part serves as the second passivation contact layer 130.

[0133] In some other embodiments, the second dielectric film and the second doping film located at the junction of the first doping region and the second doping region are removed, and after forming the second passivation contact layer, a connection layer is formed.

[0134] Continuing to refer to Figure 5 , a passivation layer 133 is formed. The passivation layer 133 covers the first doped semiconductor layer 112, the second doped semiconductor layer 132, the connection layer 140, and the junction of the first doping region 11 and the second doping region 12; a first electrode 104 is formed, and the first electrode 104 is electrically connected to the first doped semiconductor layer 112; a second electrode 105 is formed, and the second electrode 105 is electrically connected to the second doped semiconductor layer 132.

[0135] According to some embodiments of the present application, on the other hand, an embodiment of the present application provides a tandem cell, which includes: a bottom cell, the bottom cell is a back-contact solar cell prepared by the preparation method of any one of the above embodiments or the back-contact solar cell of any one of the above embodiments; a top cell, the top cell is located on the side of the substrate in the bottom cell away from the front electrode.

[0136] In some embodiments, the tandem cell has a first grid line of a first polarity and a second grid line of a second polarity. The first grid line refers to the first electrode of the back-contact solar cell, and the second grid line refers to the first electrode of the back-contact solar cell.

[0137] In some embodiments, there is an interface layer between the top cell and the bottom cell, and the interface layer also covers the passivation contact structure on the back.

[0138] It should be noted that the tandem cell in the embodiments of the present application can be a two-layer solar cell, a three-layer solar cell, or a multi-layer tandem solar cell with more than three layers.

[0139] In some embodiments, the top cell can be a perovskite solar cell, and the perovskite solar cell includes: a stacked first transport layer, a perovskite substrate, a second transport layer, a transparent conductive layer, and an antireflection layer. Among them, the first transport layer faces the bottom cell.

[0140] In some embodiments, the first transport layer can be either an electron transport layer or a hole transport layer, and the second transport layer can be the other of an electron transport layer or a hole transport layer.

[0141] According to some embodiments of the present application, on yet another aspect, an embodiment of the present application provides a photovoltaic module. Refer to Figure 15, The photovoltaic module includes: a battery string composed of a plurality of back-contact solar cells 30 as described in any one of the above embodiments or back-contact solar cells 30 prepared by the preparation method as described in any one of the above embodiments; an encapsulation film 31 for covering the surface of the battery string; and a cover plate 32 for covering the surface of the encapsulation film 31 facing away from the battery string. Among them, Figure 15 is a cross-sectional view of a photovoltaic module provided by another embodiment of the present application.

[0142] A connecting component 318 is used to electrically connect two adjacent back-contact solar cells 30. Specifically, in some embodiments, a plurality of back-contact solar cells 30 can be electrically connected through the connecting component 318, and the connecting component 318 is welded to the main grid / secondary grid on the back-contact solar cell 30.

[0143] In some embodiments, the connecting component 318 is welded to the secondary grid on the cell, and the secondary grid includes a first electrode and a second electrode. In some embodiments, the connecting component 318 is welded to the main grid on the cell, and the main grid includes a first main grid and a second main grid. The first main grid is welded to the first electrode, and the second main grid is welded to the second electrode.

[0144] In some embodiments, the encapsulation film 31 includes a first encapsulation film and a second encapsulation film. The first encapsulation film covers one of the front or back of the back-contact solar cell, and the second encapsulation film covers the other of the front or back of the back-contact solar cell. Specifically, at least one of the first encapsulation film or the second encapsulation film can be an organic encapsulation film such as a polyvinyl butyral (PVB) film, an ethylene-vinyl acetate copolymer (EVA) film, a polyethylene octene copolymer elastomer (POE) film, or a polyethylene terephthalate (PET) film.

[0145] It should be noted that there is still a demarcation line between the first encapsulation film and the second encapsulation film before the lamination process. After the lamination process to form the photovoltaic module, there will no longer be the concept of the first encapsulation film and the second encapsulation film, that is, the first encapsulation film and the second encapsulation film have formed an integral encapsulation film 31.

[0146] In some embodiments, the cover plate 32 can be a glass cover plate, a plastic cover plate, or other cover plates with a light-transmitting function. Specifically, the surface of the cover plate 32 facing the encapsulation film 31 can be an uneven surface, so as to increase the utilization rate of incident light. The cover plate 32 includes a first cover plate and a second cover plate. The first cover plate is opposite to the first encapsulation film, and the second cover plate is opposite to the second encapsulation film; or the first cover plate is opposite to one side of the back-contact solar cell, and the second cover plate is opposite to the other side of the back-contact solar cell.

[0147] Although the present application is disclosed above with preferred embodiments, it is not intended to limit the claims. Any person skilled in the art can make several possible changes and modifications without departing from the concept of the present application. Therefore, the protection scope of the present application shall be subject to the scope defined by the claims of the present application. In addition, the embodiments of the present application specification and the accompanying drawings shown are only for illustrative purposes and do not cover the entire scope protected by the claims of the present application.

[0148] Those of ordinary skill in the art can understand that the above-described embodiments are specific embodiments for implementing the present application. In actual applications, various changes can be made in form and details without departing from the spirit and scope of the present application. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the protection scope of the present application shall be subject to the scope defined by the claims.

Claims

1. A back contact solar cell, characterized in that: include: A substrate, wherein the substrate has a first surface and a second surface that are opposite to each other, and the first surface is provided with first doping regions and second doping regions that are arranged alternately; a first passivation contact layer, wherein the first passivation contact layer is located in the first doping region; doped oxide layer, each of the doped oxide layers comprises a first portion and a second portion, the first portion being located at the a surface of the first passivation contact layer; the second portion extends along an end of the first portion toward the second doping region, so that the second portion is located on the second doping region; a second passivation contact layer, the second passivation contact layer being located in the second doping region, and a doping type of the second passivation contact layer being different from a doping type of the first passivation contact layer; A connection layer is located in a partial area of ​​the first portion, the connection layer also surrounds a partial area of ​​the second portion and is electrically connected to the second passivation contact layer, and the connection layer is located on a side of the first passivation contact layer and is electrically connected to the first passivation contact layer.

2. The back contact solar cell according to claim 1, characterized in that: The length of the second portion along a first direction ranges from 0 to 3 μm, and the first direction refers to a direction from the second doping region to the first doping region.

3. The back contact solar cell according to claim 1, characterized in that: 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 first doped region has a groove relative to the second doped region, the second part is located on the groove, the connecting layer is located on the inner side of the groove, and the second passivation contact layer is located on the bottom surface of the groove.

4. The back contact solar cell according to claim 3, characterized in that: A difference between the first distance and the second distance is less than or equal to 5 μm.

5. The back contact solar cell according to claim 3, characterized in that: The first passivation contact layer is doped with P-type doping elements, and the first passivation contact layer includes a continuous third part and a fourth part, the third part is opposite to the first part, the fourth part is opposite to the second part, the fourth part is located on the groove, and the second part is located on the surface of the fourth part; the connecting layer is located on the side of the fourth part and the bottom of the fourth part away from the second part.

6. The back contact solar cell according to claim 5, characterized in that: The side surface of the fourth portion has an inwardly concave depression, and the connection layer is also located in the depression.

7. The back contact solar cell according to claim 3, characterized in that: The included angle between the bottom surface of the groove and the side surface of the groove ranges from 110° to 150°.

8. The back contact solar cell according to claim 1, characterized in that: The material of the doped oxide layer includes: borosilicate glass, phosphosilicate glass, borophosphorus glass or fluorophosphorus glass.

9. The back contact solar cell according to claim 1, characterized in that: The thickness of the connection layer is less than or equal to the thickness of the second passivation contact layer.

10. The back contact solar cell according to claim 1, characterized in that: The connection layer includes a first connection layer and a second connection layer, the first connection layer is located in a partial area of ​​the first part, the second connection layer surrounds a partial area of ​​the second part and is electrically connected to the second passivation contact layer; the thickness of the second connection layer is less than or equal to the thickness of the first connection layer.

11. The back contact solar cell according to claim 10, characterized in that: The area where the second connection layer is connected to the second passivation contact layer is a first connection area, and the remaining second connection layer is a second connection area. The thickness of the first connection area is less than the thickness of the second connection area.

12. A method for preparing a back contact solar cell, characterized in that: include: Providing a substrate, wherein the substrate has a first surface and a second surface that are oppositely disposed, and the first surface has first doped regions and second doped regions that are alternately arranged; forming a first passivation contact layer, wherein the first passivation contact layer is located in the first doped region; forming doped oxide layers, each of the doped oxide layers comprising a first portion and a second portion, the first portion being located on the surface of the first passivation contact layer; and the second portion extending along an end of the first portion toward the second doped region, so that the second portion is located on the second doped region; forming a second passivation contact layer, wherein the second passivation contact layer is located in the second doping region, and a doping type of the second passivation contact layer is different from a doping type of the first passivation contact layer; A connection layer is formed, wherein the connection layer is located in a partial area of ​​the first part, the connection layer also surrounds a partial area of ​​the second part and is electrically connected to the second passivation contact layer, and the connection layer is located on a side of the first passivation contact layer and is electrically connected to the first passivation contact layer.

13. The method for preparing a back contact solar cell according to claim 12, characterized in that: The process steps of forming the first passivation contact layer and forming the doped oxide layer include: forming a first dielectric film, a first doped film and an oxide film on the first surface of the substrate; removing the oxide film on the second doped region to expose the surface of the first doped film; removing the first dielectric film and the first doped film on the second doped region; removing part of the oxide film located in the first doped region during the process of forming the second passivation contact layer, and the remaining oxide film serves as the doped oxide film, and the remaining first dielectric film and the first doped film serve together as the first passivation contact layer.

14. The method for preparing a back contact solar cell according to claim 13, characterized in that: The process parameters for removing the first doped film on the second doped region include: the etching solution is an alkaline solution, the concentration ratio of the alkaline solution is 0.1PPM to 0.6PPM, the etching time is 20s to 500s, and the etching temperature is 50°C to 90°C.

15. A photovoltaic module, characterized in that: include: A cell string, comprising a plurality of back-contact solar cells as claimed in any one of claims 1 to 11 or a back-contact solar cell prepared by the method for preparing a back-contact solar cell as claimed in any one of claims 12 to 14; A packaging film, used to cover the surface of the battery string; The cover plate is used to cover the surface of the packaging film facing away from the battery string.

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