Back contact cell, manufacturing method thereof and photovoltaic module

Abstract

The invention relates to the technical field of photovoltaics, and provides a back contact battery, a manufacturing method thereof and a photovoltaic module, which are at least beneficial to improving the efficiency of the back contact battery. The back contact battery comprises a substrate, the substrate comprises a front surface and a back surface which are opposite, and the back surface of the substrate comprises first regions and second regions which are alternately arranged; a first tunneling layer, a first doped conductive layer, a dielectric layer and a second doped conductive layer are sequentially stacked on the first region, the dielectric layer and the second doped conductive layer are located at the edge, close to the second region, of the first doped conductive layer, and a second tunneling layer and a third doped conductive layer are sequentially stacked on the second region; the first electrode and the second electrode are located on the passivation layer, and the passivation layer covers the surfaces of the first doped conductive layer, the second doped conductive layer and the third doped conductive layer; the first electrode penetrates through the passivation layer and is in electric contact with the first doped conductive layer; and the second electrode penetrates through the passivation layer and is electrically contacted with the third doped conductive layer.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaics, and particularly relates to a back contact battery, a manufacturing method thereof, and a photovoltaic module. Background Art

[0002] At present, with the gradual depletion of fossil energy, solar cells, as a new energy alternative, are being used more and more widely. A solar cell is a device that converts the light energy of the sun into electrical energy. The solar cell utilizes the photovoltaic effect to generate carriers, and then uses electrodes to lead out the carriers, so as to facilitate the effective utilization of electrical energy.

[0003] An IBC cell (Interdigitated Back Contact), is a back-junction back-contact solar cell structure in which the front and back metal electrodes are arranged in an interdigitated manner on the backlight side of the cell, and its p-n junction is located on the back of the cell. Among them, the back-junction means that the p-n junction is located on the back of the cell.

[0004] The IBC cell is one of the photovoltaic cells with the highest conversion efficiency at present. The cell is based on single crystal silicon, and the p-n junction and metal electrodes are both located on the back of the cell. There is no metal electrode shading on the front, so a very high short-circuit current and conversion efficiency can be obtained. However, in the process of preparing the IBC cell, there are still many reasons affecting the cell performance of the IBC cell, which further limits the further improvement of the photoelectric conversion efficiency of the IBC cell. Summary of the Invention

[0005] Embodiments of the present application provide a back contact battery, a manufacturing method thereof, and a photovoltaic module, which at least help to improve the efficiency of the back contact battery.

[0006] According to some embodiments of the present application, on the one hand, an embodiment of the present application provides a back-contact battery, including: a substrate, the substrate includes an opposite front surface and a back surface, the back surface of the substrate includes an alternately arranged first region and a second region, in the thickness direction of the substrate, the surface of the first region is offset from the surface of the second region; a first tunneling layer, the first tunneling layer is located on the surface of the first region on the back surface of the substrate; a first doped conductive layer, the first doped conductive layer is located on the surface of the first tunneling layer away from the substrate; a dielectric layer, the dielectric layer is located on a part of the surface of the first doped conductive layer away from the first tunneling layer, and the dielectric layer is located at the edge of the first doped conductive layer close to the second region; a second doped conductive layer, the second doped conductive layer is located on the surface of the dielectric layer away from the first doped conductive layer, and the doping element in the second doped conductive layer is of the same type as the doping element in the first doped conductive layer; a second tunneling layer, the second tunneling layer is located on the surface of the second region on the back surface of the substrate; a third doped conductive layer, the third doped conductive layer is located on the surface of the second tunneling layer away from the substrate; a passivation layer, the passivation layer covers the surface of the first doped conductive layer away from the first tunneling layer, the surface of the second doped conductive layer away from the dielectric layer, and the surface of the third doped conductive layer away from the second tunneling layer; a first electrode, the first electrode is located on the passivation layer of the first region, and the first electrode penetrates the passivation layer and is in electrical contact with the first doped conductive layer; a second electrode, the second electrode is located on the passivation layer of the second region, and the second electrode penetrates the passivation layer and is in electrical contact with the third doped conductive layer.

[0007] In some embodiments, the concentration of the doped atoms in the second doped conductive layer is less than the concentration of the doped atoms in the first doped conductive layer.

[0008] In some embodiments, in the direction from the first region to the second region, the width of the dielectric layer is 10 μm to 200 μm.

[0009] In some embodiments, the thickness of the second doped conductive layer is greater than the thickness of the first doped conductive layer.

[0010] In some embodiments, it further includes: an isolation part, the orthographic projection of the isolation part on the surface of the substrate is located at the junction of the first region and the second region, the isolation part is located on the side surface of the first doped conductive layer close to the second region, and is located on the side surface of the third doped conductive layer close to the first region, and the isolation part is at least used to isolate the first doped conductive layer from the third doped conductive layer.

[0011] In some embodiments, the isolation part is further located on the side surface of the second doped conductive layer close to the second region to isolate the second doped conductive layer from the third doped conductive layer.

[0012] In some embodiments, in the direction from the first region to the second region, the thickness range of the isolation part is 30 μm to 100 μm.

[0013] According to some embodiments of the present application, on the other hand, the embodiments of the present application further provide a method for manufacturing a back-contact battery, comprising: providing a substrate, the substrate comprising a relative front side and a back side, the back side of the substrate comprising a first region and a second region alternately arranged; forming a first tunneling layer, a first doped conductive layer, a dielectric layer, and a second doped conductive layer in sequence in the first region on the back side of the substrate, the dielectric layer being located on a portion of the surface of the first doped conductive layer away from the first tunneling layer, and the dielectric layer being located on an edge of the first doped conductive layer close to the second region, the second doped conductive layer being located on a surface of the dielectric layer away from the first doped conductive layer, and the doping element in the second doped conductive layer being of the same type as the doping element in the first doped conductive layer; and forming a second tunneling layer and a third doped conductive layer in sequence in the second region on the back side of the substrate; forming a passivation layer, the passivation layer covering a surface of the first doped conductive layer away from the first tunneling layer, a surface of the second doped conductive layer away from the dielectric layer, and a surface of the third doped conductive layer away from the second tunneling layer; forming a first electrode and a second electrode on the passivation layers in the first region and the second region, respectively, the first electrode penetrating the passivation layer to be in electrical contact with the first doped conductive layer, and the second electrode penetrating the passivation layer to be in electrical contact with the third doped conductive layer.

[0014] In some embodiments, before forming the passivation layer, it also includes: performing laser melting processing at the junction of the first region and the second region to form an isolation portion, the isolation portion is located on the side of the first doped conductive layer close to the second region, and is located on the side of the third doped conductive layer close to the first region.

[0015] In some embodiments, the process parameters of the laser melting process include: the laser type is ultraviolet nanosecond laser or green nanosecond laser, the laser power density is 10 4 W / cm~10 6 W / cm, and the laser spot size is 30μm to 100μm.

[0016] According to some embodiments of the present application, the embodiments of the present application further provide a photovoltaic module, including: a module body, the module body including: a cell string, a bus bar, a packaging film and a cover plate; the cell string is formed by connecting a plurality of back-contact cells as in the above embodiments, or, is formed by connecting a plurality of back-contact cells formed by the manufacturing method of the back-contact cells in the above embodiments; the bus bar is used to electrically connect the cell strings; the packaging film is used to cover the surface of the cell string; the cover plate is used to cover the surface of the packaging film away from the cell string.

[0017] The technical solution provided by the embodiments of the present application has at least the following advantages:

[0018] The embodiment of the present application provides a back-contact cell and a manufacturing method thereof, as well as a photovoltaic module. The back of the back-contact cell includes a first area and a second area that are alternately arranged. The first area and the second area are staggered along the thickness direction of the substrate to improve the isolation effect of different doped conductive layers. The first area and the second area are respectively provided with a TOPCon structure composed of a tunneling layer and a doped conductive layer. The TBC cell structure formed by combining the TOPCon technology with the IBC cell has a higher photoelectric conversion efficiency, which is at least beneficial to improving the efficiency of the back-contact cell. In the conventional method of setting isolation areas at intervals, the position with the highest current density is the isolation area, which is not conducive to the collection of carriers. Compared with the conventional isolation area, the staggered first area and the second area constitute a structure without an isolation area. The minority carrier lifetime is higher in the setting without an isolation area, which is beneficial to the back-contact cell having a higher photoelectric conversion efficiency. At the same time, the absence of an isolation area is also beneficial to reducing the process steps of the graphic process, reducing the alignment requirements, and improving the manufacturing yield of the back-contact cell. A dielectric layer and a second doped conductive layer are also provided on the first doped conductive layer of the first region near the edge of the second region. The type of doping elements in the second doped conductive layer is the same as that in the first doped conductive layer. The existence of the second doped conductive layer can greatly reduce the probability of electron-hole recombination. At the same time, the second doped conductive layer is also beneficial for the highest current density area to move toward the center of the first doped conductive layer, which is more conducive to carrier collection and improves the internal resistance and current density of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise specified, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present application or the technical solutions in the traditional technology, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of the structure of a back-contact battery provided in an embodiment of the present application;

[0021] Figure 2 A schematic diagram of the structure of another back-contact battery provided in an embodiment of the present application;

[0022] Figure 3 A schematic diagram of the structure of another back contact battery provided in an embodiment of the present application;

[0023] Figures 4 to 9 A schematic structural diagram corresponding to each step of the method for manufacturing a back-contact battery provided in an embodiment of the present application;

[0024] Figure 10 A schematic diagram of the structure of a battery string provided in an embodiment of the present application;

[0025] Figure 11 A schematic diagram of the structure of a component body provided in an embodiment of the present application.

[0026] Description of reference numerals:

[0027] 100, substrate; 101, front side; 102, back side; 103, first region; 104, second region; 111, first tunneling layer; 112, first doped conductive layer; 113, dielectric layer; 114, second doped conductive layer; 121, second tunneling layer; 122, third doped conductive layer; 130, isolation portion; 140, passivation layer; 115, first electrode; 124, second electrode; 201, battery string; 202, welding ribbon; 212, first welding ribbon; 222, second welding ribbon; 232, bus bar; 203, encapsulation film; 204, cover plate. DETAILED DESCRIPTION

[0028] IBC cells can be combined with PERC (Passivated Emitter and Rear), TOPCon (Tunnel Oxide Passivated Contact), HJT (Heterojunction Technology) and other technologies to form HPBC, TBC, HBC and other structures. Among them, TBC cells have the characteristics of high conversion efficiency, beautiful appearance, and can be directly upgraded by TOPCon. It is one of the future mainstream trends of crystalline silicon cell technology and has broad commercial prospects.

[0029] The TBC battery structure currently produced by mainstream manufacturers requires laser patterning to achieve the interdigital structure of different doping areas on the back, and the isolation areas set at intervals to achieve insulation of different doping areas. The above scheme makes the battery process complicated and requires high alignment accuracy, which not only affects the battery yield and increases manufacturing costs, but the existence of the isolation area will affect the passivation effect and reduce the photoelectric conversion efficiency of the battery.

[0030] The embodiments of the present application provide a back-contact cell and a method for manufacturing the same, as well as a photovoltaic module, which are at least beneficial to improving the efficiency of the back-contact cell.

[0031] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0032] In the description of the embodiments of the present application, “plurality” means more than two, unless otherwise clearly and specifically defined.

[0033] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0034] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0035] In the description of the embodiments of the present application, technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0036] In the accompanying drawings corresponding to the embodiments of the present application, the thickness and area of ​​the layer are magnified for better understanding and ease of description. When describing a component on another component or on the surface of another component, the component may be "directly" located on the surface of the other component, or a third component may be present 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 as "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 is it formed on a partial edge of the entire surface.

[0037] 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 be further included.

[0038] The terms used in the description of the various described embodiments herein are used only to describe specific embodiments and are not intended to be limiting. As used in the description of the various described embodiments and the appended claims, "components" are also intended to include plural forms unless the context clearly indicates otherwise.

[0039] The following will describe the various embodiments of the present application in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present application, many technical details are provided in order to enable 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 solution claimed in the present application can be implemented.

[0040] Figure 1 A schematic diagram of the structure of a back-contact battery provided in an embodiment of the present application.

[0041] refer to Figure 1 The back contact battery provided in the embodiment of the present application includes: a substrate 100, a first tunneling layer 111, a first doped conductive layer 112, a dielectric layer 113, a second doped conductive layer 114, a second tunneling layer 121, a third doped conductive layer 122, a passivation layer 140, a first electrode 115 and a second electrode 124.

[0042] The substrate 100 includes a front side 101 and a back side 102 opposite to each other. The back side 102 of the substrate 100 includes first areas 103 and second areas 104 arranged alternately. In the thickness direction of the substrate 100 , the surface of the first area 103 is staggered with the surface of the second area 104 .

[0043] The first tunneling layer 111 is located on the surface of the first region 103 of the back side 102 of the substrate 100; the first doped conductive layer 112 is located on the surface of the first tunneling layer 111 away from the substrate 100; the dielectric layer 113 is located on a portion of the surface of the first doped conductive layer 112 away from the first tunneling layer 111, and the dielectric layer 113 is located at an edge of the first doped conductive layer 112 close to the second region 104; the second doped conductive layer 114 is located on the surface of the dielectric layer 113 away from the first doped conductive layer 112, and the doping element in the second doped conductive layer 114 is of the same type as the doping element in the first doped conductive layer 112.

[0044] The second tunneling layer 121 is located on the surface of the second region 104 of the back side 102 of the substrate 100 ; the third doped conductive layer 122 is located on the surface of the second tunneling layer 121 away from the substrate 100 .

[0045] The passivation layer 140 covers a surface of the first doped conductive layer 112 away from the first tunneling layer 111 , a surface of the second doped conductive layer 114 away from the dielectric layer 113 , and a surface of the third doped conductive layer 122 away from the second tunneling layer 121 .

[0046] The first electrode 115 is located on the passivation layer 140 of the first region 103 , and the first electrode 115 penetrates the passivation layer 140 to electrically contact the first doped conductive layer 112 ; the second electrode 124 is located on the passivation layer 140 of the second region 104 , and the second electrode 124 penetrates the passivation layer 140 to electrically contact the third doped conductive layer 122 .

[0047] In the back contact cell provided in the embodiment of the present application, the back side 102 of the substrate 100 includes a first area 103 and a second area 104 which are alternately arranged, and the surfaces of the first area 103 and the second area 104 are staggered along the thickness direction of the substrate 100, so that the film layers on the first area 103 and the second area 104 can be staggered to isolate the film layers on the adjacent first area 103 and the second area 104, thereby avoiding leakage problems. In the conventional method of setting isolation areas at intervals, the position with the highest current density is the isolation area, which is not conducive to the collection of carriers. Compared with the conventional isolation area, the staggered first area 103 and the second area 104 constitute a structure without isolation areas. The minority carrier lifetime of the setting without isolation areas is higher, which is conducive to the back contact cell having a higher photoelectric conversion efficiency. At the same time, the absence of isolation areas is also conducive to reducing the process steps of patterning, reducing the alignment requirements, and improving the manufacturing yield of the back contact cell. The first region 103 has a TOPCon structure consisting of a first tunneling layer 111 and a first doped conductive layer 112, and the second region 104 has a TOPCon structure consisting of a second tunneling layer 121 and a third doped conductive layer 122. The TBC cell structure formed by combining the TOPCon technology with the IBC cell has a high photoelectric conversion efficiency. The first doped conductive layer 112 also has a dielectric layer 113 and a second doped conductive layer 114 at the edge of the second region 104, and the doping element type in the second doped conductive layer 114 is the same as the doping ion type in the first doped conductive layer 112. The existence of the second doped conductive layer 114 can greatly reduce the recombination probability of electrons and holes. At the same time, the second doped conductive layer 114 is also conducive to the highest current density area moving toward the center of the first doped conductive layer 112, which is more conducive to carrier collection and improves the battery internal resistance and current density.

[0048] 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. The elemental semiconductor material may be in a single crystalline state, a polycrystalline state, an amorphous state, or a microcrystalline state (a state having both a single crystalline state and an amorphous state is referred to as a microcrystalline state). For example, silicon may be at least one of single crystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. The material of the substrate 100 may include at least one of single crystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0049] 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 germanium, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, copper indium selenide, etc. The materials may also be silicon carbide, organic materials or multi-component compounds. Multi-component compounds may include, but are not limited to, perovskite, gallium arsenide, cadmium telluride, copper indium selenide, etc.

[0050] The substrate 100 may also be a sapphire substrate, a silicon on insulator substrate, or a germanium on insulator substrate.

[0051] The substrate 100 may be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type doping element, which may be any one of the V-group elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate is doped with a P-type element, which may be any one of the III-group elements such as boron (B), aluminum (Al), gallium (Ga), or gallium (In).

[0052] The substrate 100 includes a front surface 101 and a back surface 102 . The front surface of the substrate 100 serves as a light-receiving surface for receiving incident light, and the back surface of the substrate 100 serves as a backlight surface.

[0053] In some embodiments, the front surface 101 of the substrate 100 has a velvet structure (not shown in the figure), and the velvet structure may include a pyramid velvet structure of regular shape and irregular black silicon. The inclined surface of the velvet structure can increase the internal reflection of the incident light, thereby improving the absorption utilization rate of the incident light by the substrate 100, thereby improving the battery efficiency of the back contact battery.

[0054] In some embodiments, the front side 101 of the substrate 100 may have a front surface field (FSF) (not shown in the figure), and the conductivity type of the doped ions in the front surface field is the same as the conductivity type of the doped ions in the substrate 100. The field passivation effect is used to reduce the surface minority carrier concentration, thereby reducing the surface recombination rate. At the same time, the series resistance can also be reduced and the electron transmission capacity can be improved.

[0055] The front side of the back contact battery may also include: a front passivation layer (not shown in the figure), which is located on the front side and is regarded as a front passivation layer. The front passivation layer may be a single-layer structure or a stacked-layer structure, for example, the single-layer structure may be a single-layer aluminum oxide film layer, a single-layer silicon oxide film layer, a single-layer silicon nitride film layer or a single-layer silicon oxynitride film layer; the stacked-layer structure may be composed of at least two film layers of an aluminum oxide film layer, a silicon oxide film layer, a silicon nitride film layer or a silicon oxynitride film layer stacked together.

[0056] The surface of the first area 103 and the surface of the second area 104 of the back side 102 of the substrate 100 may be polished surfaces, which refer to a flat surface formed by removing the velvet structure on the surface by a polishing solution or laser etching. After polishing, the flatness of the back side increases, the reflection of long-wave light increases, and the secondary absorption of the projected light is promoted, thereby increasing Isc. At the same time, due to the reduction in the specific surface area of ​​the back side, the back side recombination is reduced, and the back side passivation effect can be improved.

[0057] In some embodiments, the surface of the second region 104 is closer to the front side of the substrate 100 than the surface of the first region 103. Since the number of film layers on the first region 103 is greater than the number of film layers on the second region 104, the surface of the second region 104 is closer to the front side of the substrate 100 than the surface of the first region 103. The film layer on the first region 103 can be formed first, and then patterning is performed to remove the film layer on the second region 104 and a portion of the thickness of the substrate 100, and then a corresponding film layer is formed on the second region 104, which is beneficial to reduce the number of patterning times and improve the manufacturing efficiency of the back contact battery.

[0058] The first tunneling layer 111 and the first doped conductive layer 112 are used to form a passivation contact structure. The first tunneling layer 111 can play a chemical passivation effect. Due to the presence of interface state defects on the surface of the substrate 100, the first tunneling layer 111 can saturate the dangling bonds on the surface of the substrate 100, reduce the defect state density on the surface of the substrate 100, and reduce the recombination centers on the surface of the substrate 100 to reduce the carrier recombination rate, so that the interface state density on the surface of the substrate 100 is relatively large. The increase in the interface state density will promote the recombination of photogenerated carriers, increase the fill factor, short-circuit current and open-circuit voltage of the back contact battery, so as to improve the photoelectric conversion efficiency of the back contact battery; the first doped conductive layer 112 can have a field passivation effect. The first doped conductive layer 112 can form an electrostatic field, thereby allowing minority carriers to escape from the interface, reducing the concentration of minority carriers, so that the carrier recombination rate at the interface of the substrate 100 is relatively low, increasing the open circuit voltage, short-circuit current and fill factor of the back contact battery, and improving the photoelectric conversion efficiency of the back contact battery.

[0059] Similarly, the second tunneling layer 121 and the third doped conductive layer 122 are used to form a passivation contact structure, and the action mechanism thereof is the same as that of the first tunneling layer 111 and the first doped conductive layer 112 , which will not be described in detail herein.

[0060] The material of the first tunnel layer 111 and the material of the second tunnel layer 121 may each include at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride.

[0061] The doping ion type in one of the first doped conductive layer 112 or the third doped conductive layer 122 is the same as the doping ion type in the substrate 100, and the doping ion type in the other of the first doped conductive layer 112 or the third doped conductive layer 122 is opposite to the doping ion type in the substrate 100. For example, the substrate 100 has P-type doping ions, the first doped conductive layer 112 has N-type doping ions, and the second doped conductive layer has P-type doping ions; or, the substrate 100 has P-type doping ions, the first doped conductive layer 112 has P-type doping ions, and the second doped conductive layer has N-type doping ions; or, the substrate 100 has N-type doping ions, the first doped conductive layer 112 has N-type doping ions, and the second doped conductive layer has P-type doping ions; or, the substrate 100 has N-type doping ions, the first doped conductive layer 112 has N-type doping ions, and the second doped conductive layer has P-type doping ions; or, the substrate 100 has N-type doping ions, the first doped conductive layer 112 has P-type doping ions, and the second doped conductive layer has N-type doping ions.

[0062] In this embodiment, the doping ions in the first doped conductive layer 112 are N-type doping ions, the doping ions in the third doped conductive layer 122 are P-type doping ions, and the thickness of the second tunneling layer 121 is greater than the thickness of the first tunneling layer 111. Since the carriers in the P-type doped layer are holes, their effective mass is usually greater than that of electrons, and the tunneling probability is low, a thicker tunneling layer is required to maintain sufficient tunneling current, and the hole tunneling barrier at the top of the valence band of the P-type doped layer is high, and a thicker tunneling layer is required to reduce the barrier.

[0063] In this embodiment, the thickness of the first tunneling layer 111 is 1 nm to 2 nm, for example, it can be 1 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.6 nm, 1.7 nm, 1.8 nm, 1.9 nm or 2 nm. The thickness of the second tunneling layer 121 can be 1.1 nm to 2.5 nm, for example, it can be 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.6 nm, 1.7 nm, 1.8 nm, 1.9 nm, 2 nm, 2.1 nm, 2.2 nm, 2.3 nm, 2.4 nm or 2.5 nm.

[0064] In other embodiments, the doping ions in the first doped conductive layer 112 are P-type doping ions, and the doping ions in the third doped conductive layer 122 are N-type doping ions, and the thickness of the second tunneling layer 121 may be smaller than the thickness of the first tunneling layer 111 .

[0065] The material of the first doped conductive layer 112 and the material of the third doped conductive layer 122 may each include at least one of amorphous silicon, polycrystalline silicon, or silicon carbide.

[0066] The thickness of the first doped conductive layer 112 may be 100 nm to 300 nm, for example, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, 230 nm, 260 nm, 290 nm or 300 nm.

[0067] The thickness of the third doped conductive layer 122 may be 100 nm to 300 nm, for example, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, 230 nm, 260 nm, 290 nm or 300 nm.

[0068] In this embodiment, the doping ions in the first doped conductive layer 112 are N-type doping ions, the doping ions in the third doped conductive layer 122 are P-type doping ions, and the concentration of the doping ions in the third doped conductive layer 122 is less than the concentration of the doping ions in the first doped conductive layer 112. Since the electron mobility in the N-type doping layer is higher than that of the hole, the N-type doping layer requires a higher doping concentration to achieve the same conductivity as the P-type doping layer, and high-concentration doping is beneficial to improving the passivation effect of the N-type doping layer, reducing surface recombination, and improving electron collection efficiency.

[0069] In this embodiment, the concentration of doping ions in the first doped conductive layer 112 is 1×10 20 atoms / cm 3 ~8×10 20 atoms / cm 3 , for example, it can be 1×10 20 atoms / cm 3 , 2×10 20 atoms / cm 3 , 3×10 20 atoms / cm 3 , 4×10 20 atoms / cm 3 , 5×10 20 atoms / cm 3 , 6×10 20 atoms / cm 3 ,7×10 20 atoms / cm 3 or 8×10 20 atoms / cm 3 The concentration of doped ions in the third doped conductive layer 122 is 1×10 19 atoms / cm 3 ~3×10 20 atoms / cm 3 , for example, it can be 1×10 19atoms / cm 3 , 5×10 19 atoms / cm 3 , 8×10 19 atoms / cm 3 , 1×10 20 atoms / cm 3 , 1.5×10 20 atoms / cm 3 , 2×10 20 atoms / cm 3 , 2.5×10 20 atoms / cm 3 or 3×10 20 atoms / cm 3 .

[0070] In other embodiments, the doping ions in the first doped conductive layer 112 are P-type doping ions, and the doping ions in the third doped conductive layer 122 are N-type doping ions, and the concentration of the doping ions in the third doped conductive layer 122 is greater than the concentration of the doping ions in the first doped conductive layer 112 .

[0071] The material of the dielectric layer 113 may include silicon oxide, silicon nitride, borosilicate glass, phosphosilicate glass, or the like.

[0072] The thickness of the dielectric layer 113 is greater than 0 and less than or equal to 30 nm, for example, may be 2 nm, 6 nm, 10 nm, 13 nm, 15 nm, 17 nm, 20 nm, 22 nm, 25 nm, 28 nm or 30 nm.

[0073] In some embodiments, in the direction from the first region 103 to the second region 104, the width of the dielectric layer 113 is 10 μm to 200 μm, for example, 10 μm, 20 μm, 30 μm, 40 μm, 60 μm, 80 μm, 100 μm, 110 μm, 130 μm, 150 μm, 170 μm, 190 μm or 200 μm.

[0074] Correspondingly, in the direction from the first region 103 to the second region 104 , the width of the second doped conductive layer 114 is equal to the width of the dielectric layer 113 .

[0075] In some embodiments, the concentration of doping atoms in the second doped conductive layer 114 is less than the concentration of doping atoms in the first doped conductive layer 112. In this way, the area with the highest current density can be promoted to move toward the center of the first doped conductive layer 112, which is beneficial to carrier collection and improves the internal resistance and current density of the battery.

[0076] In some embodiments, the concentration of doping atoms in the second doped conductive layer 114 is less than the concentration of doping atoms in the first doped conductive layer 112, and less than the concentration of doping atoms in the third doped conductive layer 122. This is conducive to promoting the highest current density area to move to the center of the first doped conductive layer 112 and the center of the third doped conductive layer 122, thereby facilitating carrier collection and improving the internal resistance and current density of the battery.

[0077] The concentration of doping atoms in the second doped conductive layer 114 is 1×10 19 atoms / cm 3 ~5×10 20 atoms / cm 3 , for example, it can be 1×10 19 atoms / cm 3 , 5×10 19 atoms / cm 3 , 8×10 19 atoms / cm 3 , 1×10 20 atoms / cm 3 , 1.5×10 20 atoms / cm 3 , 2×10 20 atoms / cm 3 , 2.5×10 20 atoms / cm 3 , 3×10 20 atoms / cm 3 , 4×10 20 atoms / cm 3 or 5×10 20 atoms / cm 3 .

[0078] In some embodiments, the thickness of the second doped conductive layer 114 may be greater than the thickness of the first doped conductive layer 112. This can help reduce the recombination probability of electrons and holes, reduce the risk of leakage, and thus improve the back contact cell to have a higher photoelectric conversion efficiency.

[0079] The thickness of the second doped conductive layer 114 is 100 nm to 300 nm, for example, may be 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, 230 nm, 260 nm, 290 nm or 300 nm.

[0080] In some embodiments, along the thickness direction of the substrate 100, the distance between the surface of the first region 103 and the surface of the second region 104 is at least greater than the sum of the thickness of the second tunneling layer 121 and the thickness of the third doped conductive layer 122. In this way, the first doped conductive layer 112 and the third doped conductive layer 122 can be physically isolated by a staggered arrangement.

[0081] Figure 2 A schematic diagram of the structure of another back-contact battery provided in an embodiment of the present application.

[0082] refer to Figure 2 In some embodiments, the isolation portion 130 is also included. The orthographic projection of the isolation portion 130 on the surface of the substrate 100 is located at the junction of the first area 103 and the second area 104. The isolation portion 130 is located on the side of the first doped conductive layer 112 close to the second area 104, and is located on the side of the third doped conductive layer 122 close to the first area 103. The isolation portion 130 is at least used to isolate the first doped conductive layer 112 from the third doped conductive layer 122. The isolation portion 130 can further enhance the isolation effect between the first doped conductive layer 112 and the third doped conductive layer 122 on the basis of the staggered arrangement.

[0083] It should be noted that in Figure 2 In the embodiment, in the thickness direction of the substrate 100, the example that the end of the isolation portion 130 close to the front surface 101 of the substrate 100 is flush with the surface of the first tunneling layer 121 close to the front surface 101 of the substrate 100 does not constitute a limitation on the position of the end of the isolation portion 130 close to the front surface 101 of the substrate 100. In other embodiments, the end of the isolation portion 130 close to the front surface 101 of the substrate 100 may also be flush with the surface of the third doped conductive layer 122 close to the front surface 101 of the substrate 100, or the distance between the end of the isolation portion 130 close to the front surface 101 of the substrate 100 and the front surface of the substrate 100 may also be less than the distance between the surface of the first tunneling layer 121 close to the front surface 101 of the substrate 100 and the front surface of the substrate 100. As long as the distance between one end of the isolation portion 130 close to the front side 101 of the substrate 100 and the front side of the substrate 100 is smaller than the distance between one side surface of the third doped conductive layer 122 close to the front side 101 of the substrate 100 and the front side of the substrate 100, the isolation portion 130 can at least isolate the third doped layer 122 from the first doped layer 112.

[0084] Figure 3 A schematic diagram of the structure of another back-contact battery provided in an embodiment of the present application.

[0085] refer to Figure 3In some embodiments, the isolation portion 130 is also located on the side of the second doped conductive layer 114 close to the second region 104 to isolate the second doped conductive layer 114 from the third doped conductive layer 122 to further avoid leakage problems between the second doped conductive layer 114 and the third doped conductive layer 122.

[0086] When the first doped conductive layer 112 and the third doped conductive layer 122 are isolated by the isolation portion 130, in the thickness direction of the substrate 100, the distance between the surface of the first region 103 and the surface of the second region 104 can be less than or equal to the sum of the thickness of the second tunneling layer 121 and the thickness of the third doped conductive layer 122, that is, the first doped conductive layer 112 and the third doped conductive layer 122 are directly isolated by the isolation portion 130.

[0087] The material of the isolation part 130 includes polysilicon.

[0088] In some embodiments, the thickness of the isolation portion 130 in the direction from the first region 103 to the second region 104 is in the range of 30um to 100um. 30μm to 100μm, for example, may be 30μm, 34μm, 40μm, 45μm, 50μm, 56μm, 70μm, 74μm, 80μm, 85μm, 90μm, 93μm or 100μm. The thickness of the isolation portion 130 in the direction from the first region 103 to the second region 104 needs to be in an appropriate range to avoid the isolation portion 130 occupying too much area, resulting in a reduction in the passivation effect of the back passivation structure.

[0089] The material of the passivation layer 140 may include at least one of aluminum oxide, silicon oxide, silicon nitride, or silicon oxynitride. The passivation layer 140 may be a single-layer structure or a stacked-layer structure. For example, the single-layer structure may be a single-layer aluminum oxide film layer, a single-layer silicon oxide film layer, a single-layer silicon nitride film layer, or a single-layer silicon oxynitride film layer; the stacked-layer structure may be composed of at least two film layers stacked among an aluminum oxide film layer, a silicon oxide film layer, a silicon nitride film layer, or a silicon oxynitride film layer.

[0090] The thickness of the passivation layer 140 may be 65 nm to 100 nm, for example, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm or 100 nm.

[0091] The material of the first electrode 115 and the material of the second electrode 124 may each include one or more of aluminum, silver, gold, nickel, molybdenum, or copper.

[0092] In the back contact cell provided in the embodiment of the present application, the back side 102 of the substrate 100 includes a first area 103 and a second area 104 which are alternately arranged, and the surfaces of the first area 103 and the second area 104 are staggered along the thickness direction of the substrate 100, so that the film layers on the first area 103 and the second area 104 can be staggered to isolate the film layers on the adjacent first area 103 and the second area 104, thereby avoiding leakage problems. In the conventional method of setting isolation areas at intervals, the position with the highest current density is the isolation area, which is not conducive to the collection of carriers. Compared with the conventional isolation area, the staggered first area 103 and the second area 104 constitute a structure without isolation areas. The minority carrier lifetime of the setting without isolation areas is higher, which is conducive to the back contact cell having a higher photoelectric conversion efficiency. At the same time, the absence of isolation areas is also conducive to reducing the process steps of patterning, reducing the alignment requirements, and improving the manufacturing yield of the back contact cell. The first region 103 has a TOPCon structure consisting of a first tunneling layer 111 and a first doped conductive layer 112, and the second region 104 has a TOPCon structure consisting of a second tunneling layer 121 and a third doped conductive layer 122. The TBC cell structure formed by combining the TOPCon technology with the IBC cell has a high photoelectric conversion efficiency. The first doped conductive layer 112 also has a dielectric layer 113 and a second doped conductive layer 114 at the edge of the second region 104, and the doping element type in the second doped conductive layer 114 is the same as the doping ion type in the first doped conductive layer 112. The existence of the second doped conductive layer 114 can greatly reduce the recombination probability of electrons and holes. At the same time, the second doped conductive layer 114 is also conducive to the highest current density area moving toward the center of the first doped conductive layer 112, which is more conducive to carrier collection and improves the battery internal resistance and current density.

[0093] Correspondingly, another embodiment of the present application also provides a method for manufacturing a back-contact battery, which can be used to manufacture the back-contact battery provided in the above embodiment. The method for manufacturing a back-contact battery provided in another embodiment of the present application will be described in detail below in conjunction with the accompanying drawings. For the parts that are the same or corresponding to the previous embodiment, refer to the corresponding description of the previous embodiment, and will not be described in detail below.

[0094] The manufacturing method of the back-contact battery provided in the embodiment of the present application includes: providing a substrate, the substrate includes a relative front side and a back side, the back side of the substrate includes a first area and a second area arranged alternately; forming a first tunneling layer, a first doped conductive layer, a dielectric layer, and a second doped conductive layer in the first area on the back side of the substrate in sequence, the dielectric layer is located on a portion of the surface of the first doped conductive layer away from the first tunneling layer, and the dielectric layer is located on the edge of the first doped conductive layer close to the second area, the second doped conductive layer is located on the surface of the dielectric layer away from the first doped conductive layer, and the doping element in the second doped conductive layer is of the same type as the doping element in the first doped conductive layer; and forming a second tunneling layer and a third doped conductive layer in sequence in the second area on the back side of the substrate; forming a passivation layer, the passivation layer covering the surface of the first doped conductive layer away from the first tunneling layer, the surface of the second doped conductive layer away from the dielectric layer, and the surface of the third doped conductive layer away from the second tunneling layer; forming a first electrode and a second electrode on the passivation layers in the first area and the second area, respectively, the first electrode penetrates the passivation layer to electrically contact the first doped conductive layer, and the second electrode penetrates the passivation layer to electrically contact the third doped conductive layer.

[0095] In some embodiments, the first tunneling layer, the first doped conductive layer, the dielectric layer, and the second doped conductive layer may be formed on the first region first, and then the second tunneling layer and the third doped conductive layer may be formed on the second region. In other embodiments, the first tunneling layer and the first doped conductive layer may be formed on the first region first, and then the second tunneling layer and the third doped conductive layer may be formed on the second region, and finally the dielectric layer and the second doped conductive layer may be formed on the first region.

[0096] Figures 4 to 9 A schematic structural diagram corresponding to each step of the method for manufacturing a back-contact battery provided in an embodiment of the present application.

[0097] In one example, the steps of first forming a first tunneling layer, a first doped conductive layer, a dielectric layer, and a second doped conductive layer on the first region, and then forming a second tunneling layer and a third doped conductive layer on the second region are as follows:

[0098] refer to Figure 4 A substrate 100 is provided, wherein the substrate 100 includes a front side 101 and a back side 102 opposite to each other, and the back side 102 of the substrate 100 includes first areas 103 and second areas 104 which are alternately arranged.

[0099] refer to Figure 5 A first tunneling layer 111 , a first doped conductive layer 112 , a dielectric layer 113 and a second doped conductive layer 114 are sequentially formed on the back side of the substrate 100 .

[0100] refer to Figure 6, perform patterning to remove the first tunneling layer 111, the first doped conductive layer 112, the dielectric layer 113, and the second doped conductive layer 114 on the second region 104, as well as a portion of the thickness of the substrate 100, and remove a portion of the dielectric layer 113 and the second doped conductive layer 114 in the first region 103. The remaining dielectric layer 113 and the second doped conductive layer 114 are located at the edge of the first doped conductive layer 112 close to the second region 104. Patterning can be performed by laser etching or selective etching after forming a mask layer.

[0101] Reference Figure 7 , form a second tunneling layer 121 and a third doped conductive layer 122 in the second region 104.

[0102] Return reference Figure 1 , form a passivation layer 140, where the passivation layer 140 covers the surfaces of the first doped conductive layer 112, the second doped conductive layer 114, and the third doped conductive layer 122; and form a first electrode 115 and a second electrode 124 on the passivation layer 140 in the first region 103 and the second region 104 respectively. The first electrode 115 penetrates the passivation layer 140 and is in electrical contact with the first doped conductive layer 112, and the second electrode 124 penetrates the passivation layer 140 and is in electrical contact with the third doped conductive layer 122.

[0103] In another example, the specific steps of first forming the first tunneling layer and the first doped conductive layer on the first region, then forming the second tunneling layer and the third doped conductive layer on the second region, and finally forming the dielectric layer and the second doped conductive layer on the first region are as follows:

[0104] Reference Figure 4 , provide a substrate 100, where the substrate 100 includes an opposite front surface 101 and a back surface 102, and the back surface 102 of the substrate 100 includes an alternately arranged first region 103 and a second region 104.

[0105] Reference Figure 8 , sequentially form a first tunneling layer 111 and a first doped conductive layer 112 on the back surface 102 of the substrate 100; perform patterning to remove the first tunneling layer 111 and the first doped conductive layer 112 on the second region 104 and a portion of the thickness of the substrate 100.

[0106] Reference Figure 9 , form a second tunneling layer 121 and a third doped conductive layer 122 in the second region 104.

[0107] Return reference Figure 7 , form a dielectric layer 113 and a second doped conductive layer 114 on the edge of the first doped conductive layer 112 close to the second region 104.

[0108] In the process of forming the second tunneling layer 121, the third doped conductive layer 122, the dielectric layer 113, and the second doped conductive layer 114, a mask layer can be covered at places where the corresponding film layers do not need to be formed. The material of the mask layer can be selected from mask materials for photolithography development or laser patterning, or printable gum mask materials, etc.

[0109] Return reference Figure 1 , forming a passivation layer 140 that covers the surfaces of the first doped conductive layer 112, the second doped conductive layer 114, and the third doped conductive layer 122; and forming a first electrode 115 and a second electrode 124 on the passivation layer 140 in the first region 103 and the second region 104 respectively. The first electrode 115 penetrates through the passivation layer 140 and is in electrical contact with the first doped conductive layer 112, and the second electrode 124 penetrates through the passivation layer 140 and is in electrical contact with the third doped conductive layer 122.

[0110] In some embodiments, before forming the passivation layer, it further includes: performing a laser melting treatment at the junction of the first region and the second region to form an isolation portion. The isolation portion is located on the side of the first doped conductive layer close to the second region and on the side of the third doped conductive layer close to the first region. By performing a laser melting treatment at the junction of the first region and the second region, at least the first doped conductive layer and the third doped conductive layer at the junction are melted. After the polysilicon at the junction is remelted, a neutral isolation portion is formed. After cooling, the isolation portion turns into an amorphous state, and the conductivity is greatly reduced, so that the leakage problem between the first doped conductive layer and the third doped conductive layer is significantly reduced.

[0111] Referring to the manufacturing methods of the above two back-contact batteries, the formation sequence of each film layer and the sequence of the laser melting treatment can be adjusted to obtain the back-contact batteries in the above embodiments.

[0112] For example, in combination with the above steps of first forming the first tunneling layer, the first doped conductive layer, the dielectric layer, and the second doped conductive layer on the first region, and then forming the second tunneling layer and the third doped conductive layer on the second region, referring to Figure 7 , after forming the second tunneling layer 121 and the third doped conductive layer 122 in the second region 104, before forming the passivation layer 140, perform a laser melting treatment at the junction of the first region 103 and the second region 104. Thus, the back-contact battery shown in Figure 3 is formed. Or, in combination with the above specific steps of first forming the first tunneling layer and the first doped conductive layer on the first region, then forming the second tunneling layer and the third doped conductive layer on the second region, and finally forming the dielectric layer and the second doped conductive layer on the first region, referring to Figure 9, after the second tunneling layer 121 and the third doped conductive layer 122 are formed in the second region 104, before the dielectric layer 113 and the second doped conductive layer 114 are formed, a laser melting treatment is performed at the junction of the first region 103 and the second region 104. Thus, the Figure 2 back-contact battery shown is formed.

[0113] In some embodiments, the process parameters of the laser melting treatment include: the type of laser is ultraviolet nanosecond laser or green nanosecond laser; the power density of the laser is 10 4 W / cm to 10 6 W / cm, for example, specifically it can be 10 4 W / cm, 10 5 W / cm or 10 6 W / cm; the spot size of the laser is 30μm to 100μm, for example, specifically it can be 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm or 100μm.

[0114] For the manufacturing method of the back-contact battery provided by the embodiments of the present application, the back surface 102 of the substrate 100 includes an alternately arranged first region 103 and a second region 104. The surfaces of the first region 103 and the second region 104 are arranged in a dislocation manner along the thickness direction of the substrate 100. In this way, the film layers on the first region 103 and the second region 104 can be isolated in a staggered layer, avoiding the problem of leakage current between the film layers on the adjacent first region 103 and second region 104. In the conventional method of arranging isolation regions at intervals, the position with the highest current density is the isolation region, which is not conducive to the collection of carriers. Compared with the conventional isolation region, the first region 103 and the second region 104 arranged in a staggered layer form a structure without an isolation region. The setting of the non-isolation region has a higher minority carrier lifetime, which is beneficial for the back-contact battery to have a higher photoelectric conversion efficiency. At the same time, the non-isolation region is also beneficial for reducing the patterning process steps, reducing the alignment requirements, and improving the manufacturing yield of the back-contact battery. A TOPCon structure composed of a first tunneling layer 111 and a first doped conductive layer 112 is formed on the first region 103, and a TOPCon structure composed of a second tunneling layer 121 and a third doped conductive layer 122 is formed on the second region 104. Thus, combining the TOPCon technology with the IBC battery to form a TBC battery structure has a higher photoelectric conversion efficiency. A dielectric layer 113 and a second doped conductive layer 114 are also formed at the edge of the first doped conductive layer 112 close to the second region 104, and the type of doping element in the second doped conductive layer 114 is the same as the type of doping ions in the first doped conductive layer 112. The presence of the second doped conductive layer 114 can greatly reduce the recombination probability of electrons and holes. At the same time, the second doped conductive layer 114 is also beneficial for the highest region of the current density to move towards the center of the first doped conductive layer 112, which is more conducive to carrier collection and improves the battery internal resistance and current density.

[0115] According to some embodiments of the present application, on the other hand, an embodiment of the present application further provides a photovoltaic module, including: a plurality of back-contact batteries as described in the above embodiments, or back-contact batteries formed by the manufacturing methods of a plurality of back-contact batteries in the above embodiments. The photovoltaic module provided by another embodiment of the present application will be described in detail below with reference to the accompanying drawings. For the same or corresponding parts as the previous embodiment, reference may be made to the corresponding description of the previous embodiment, and details will not be repeated below.

[0116] Figure 10 It is a schematic structural diagram of a battery string provided by an embodiment of the present application; Figure 11 It is a schematic structural diagram of a module body provided by an embodiment of the present application.

[0117] Reference Figure 10 and Figure 11 According to the present application, the photovoltaic module provided by the embodiment of the present application includes: a module body, and the module body includes: a battery string 201, a bus bar 232, an encapsulation film 203, and a cover plate 204.

[0118] The battery string 201 is formed by connecting a plurality of back-contact batteries as described in the above embodiments, or formed by connecting back-contact batteries formed by the manufacturing methods of a plurality of back-contact batteries in the above embodiments.

[0119] A plurality of back-contact batteries in the battery string 201 can be connected by solder tapes 202.

[0120] Reference Figure 10 , adjacent back-contact batteries can be connected by a first solder tape 212 and a second solder tape 222. For example, for the back-contact battery located in the middle position in Figure 10 , the main grid of the first polarity of this back-contact battery is connected to the main grid of the second polarity of another back-contact battery on the left by the first solder tape 212, and the main grid of the second polarity of this back-contact battery is connected to the main grid of the first polarity of another back-contact battery on the right by the second solder tape 222. The first polarity is one of the positive electrode or the negative electrode, and the second polarity is the other of the positive electrode or the negative electrode. In this way, a plurality of back-contact batteries are connected in series in sequence.

[0121] In other embodiments, a plurality of back-contact batteries can also be connected in parallel in sequence.

[0122] The bus bar is used for electrically connecting the battery string 201. Taking the parallel connection of two battery strings by the bus bar 232 in Figure 11 as an example, in other embodiments, the bus bar 232 can also be used for connecting two battery strings in series.

[0123] Reference Figure 11 , the encapsulation film 203 is used for covering the surface of the battery string 201.

[0124] The material of the encapsulation film 203 can be an organic encapsulation film such as ethylene-vinyl acetate copolymer (EVA) film, polyolefin elastomer (POE) film, or polyvinyl butyral (PVB) film.

[0125] Reference Figure 11 , and the cover plate 204 is used to cover the surface of the encapsulation film 203 away from the battery string 201.

[0126] The cover plate 204 can be a cover plate with a light-transmitting function such as a glass cover plate or a plastic cover plate. In some embodiments, the surface of the cover plate 204 facing the encapsulation film 203 can be an uneven surface, so as to increase the utilization rate of incident light.

[0127] In the photovoltaic module provided by the embodiment of the present application, the back surface of the back-contact battery includes alternately arranged first regions and second regions, and the first regions and the second regions are arranged in a staggered layer along the thickness direction of the substrate, so as to improve the isolation effect of different doped conductive layers. The first regions and the second regions respectively have a TOPCon structure composed of a tunneling layer and a doped conductive layer. Combining the TOPCon technology with the IBC battery to form a TBC battery structure has a high photoelectric conversion efficiency, which is at least beneficial to improving the efficiency of the back-contact battery. In the conventional way of arranging isolation regions at intervals, the position with the highest current density is the isolation region, which is not conducive to the collection of carriers. Compared with the conventional isolation region, the first regions and the second regions arranged in a staggered layer form a structure without an isolation region. The structure without an isolation region has a higher minority carrier lifetime, which is beneficial to the back-contact battery having a high photoelectric conversion efficiency. At the same time, the structure without an isolation region is also beneficial to reducing the patterning process steps, reducing the alignment requirements, and improving the manufacturing yield of the back-contact battery. At the edge of the first doped conductive layer of the first region close to the second region, there is also a dielectric layer and a second doped conductive layer. The type of doping element in the second doped conductive layer is the same as that in the first doped conductive layer. The existence of the second doped conductive layer can greatly reduce the recombination probability of electrons and holes. At the same time, the second doped conductive layer is also beneficial to moving the region with the highest current density towards the center of the first doped conductive layer 112, which is more beneficial to carrier collection and improves the battery internal resistance and current density.

[0128] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present application. In actual applications, various changes can be made in form and details without departing from the spirit and scope of the present application. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the protection scope of the present application should be subject to the scope defined by the claims.

Claims

1. A back contact battery, characterized in that: include: A substrate, the substrate comprising a front side and a back side opposite to each other, the back side of the substrate comprising first areas and second areas arranged alternately, and in a thickness direction of the substrate, a surface of the first area and a surface of the second area are arranged in a staggered manner; A first tunneling layer, wherein the first tunneling layer is located on a surface of the first region on the back side of the substrate; a first doped conductive layer, wherein the first doped conductive layer is located on a surface of the first tunneling layer away from the substrate; a dielectric layer, wherein the dielectric layer is located on a portion of the surface of the first doped conductive layer away from the first tunneling layer, and the dielectric layer is located on an edge of the first doped conductive layer close to the second region; a second doped conductive layer, the second doped conductive layer being located on a surface of the dielectric layer away from the first doped conductive layer, and the doping element in the second doped conductive layer is of the same type as the doping element in the first doped conductive layer; A second tunneling layer, wherein the second tunneling layer is located on a surface of the second region on the back side of the substrate; a third doped conductive layer, the third doped conductive layer being located on a surface of the second tunneling layer away from the substrate; a passivation layer, the passivation layer covering a surface of the first doped conductive layer away from the first tunneling layer, a surface of the second doped conductive layer away from the dielectric layer, and a surface of the third doped conductive layer away from the second tunneling layer; a first electrode, the first electrode being located on the passivation layer in the first region, the first electrode penetrating the passivation layer and being in electrical contact with the first doped conductive layer; A second electrode is located on the passivation layer in the second region, and the second electrode penetrates the passivation layer and is in electrical contact with the third doped conductive layer.

2. The back contact battery according to claim 1, characterized in that: The concentration of doping atoms in the second doped conductive layer is less than the concentration of doping atoms in the first doped conductive layer.

3. The back contact battery according to claim 1, characterized in that: In a direction from the first region to the second region, the width of the dielectric layer is 10 μm to 200 μm.

4. The back contact battery according to claim 1, characterized in that: The thickness of the second doped conductive layer is greater than the thickness of the first doped conductive layer.

5. The back contact battery according to claim 1, characterized in that: Also includes: An isolation portion, wherein the orthographic projection of the isolation portion on the surface of the substrate is located at the junction of the first region and the second region, the isolation portion is located on the side of the first doped conductive layer close to the second region, and is located on the side of the third doped conductive layer close to the first region, and the isolation portion is at least used to isolate the first doped conductive layer from the third doped conductive layer.

6. The back contact battery according to claim 5, characterized in that: The isolation portion is also located at a side of the second doped conductive layer close to the second region, so as to isolate the second doped conductive layer from the third doped conductive layer.

7. The back contact battery according to claim 5, characterized in that: In a direction from the first region to the second region, the thickness of the isolation portion ranges from 30 um to 100 um.

8. A method for manufacturing a back contact battery, characterized in that: include: Providing a substrate, the substrate comprising a front side and a back side opposite to each other, the back side of the substrate comprising first areas and second areas arranged alternately; A first tunneling layer, a first doped conductive layer, a dielectric layer, and a second doped conductive layer are sequentially formed in the first region on the back side of the substrate, the dielectric layer is located on a portion of the surface of the first doped conductive layer away from the first tunneling layer, and the dielectric layer is located on an edge of the first doped conductive layer close to the second region, the second doped conductive layer is located on a surface of the dielectric layer away from the first doped conductive layer, and the doping element in the second doped conductive layer is of the same type as the doping element in the first doped conductive layer; and a second tunneling layer and a third doped conductive layer are sequentially formed in the second region on the back side of the substrate; forming a passivation layer, wherein the passivation layer covers a surface of the first doped conductive layer away from the first tunneling layer, a surface of the second doped conductive layer away from the dielectric layer, and a surface of the third doped conductive layer away from the second tunneling layer; A first electrode and a second electrode are formed on the passivation layer in the first region and the second region, respectively. The first electrode penetrates the passivation layer and is in electrical contact with the first doped conductive layer. The second electrode penetrates the passivation layer and is in electrical contact with the third doped conductive layer.

9. The method for manufacturing a back contact battery according to claim 8, characterized in that: Before forming the passivation layer, the method further comprises: Laser melting is performed at the junction of the first region and the second region to form an isolation portion, wherein the isolation portion is located on a side of the first doped conductive layer close to the second region and on a side of the third doped conductive layer close to the first region.

10. The method for manufacturing a back contact battery according to claim 9, characterized in that: The process parameters of the laser melting process include: the laser type is ultraviolet nanosecond laser or green nanosecond laser, the laser power density is 10 4 W / cm~10 6 W / cm, and the laser spot size is 30μm to 100μm.

11. A photovoltaic module, characterized in that: include: The component body includes: a battery string, a bus bar, a packaging film and a cover plate; The battery string is formed by connecting a plurality of back-contact batteries according to any one of claims 1 to 7, or by connecting a plurality of back-contact batteries formed by the method for manufacturing a back-contact battery according to any one of claims 8 to 10; The bus bar is used to electrically connect the battery strings; The packaging film is used to cover the surface of the battery string; The cover plate is used to cover the surface of the packaging film away from the battery string.

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