Solar cell and its manufacturing method

Abstract

Embodiments of the present disclosure relate to the field of photovoltaics, and provide a battery chip and a manufacturing method thereof. The battery chip includes: a substrate, the substrate including an opposite front side and a back side; a front electrode, the front electrode being located on the front side; at least one doping structure, the doping structure being located on the back side, and the doping structure containing first-type doping ions; a tunneling layer, the tunneling layer at least covering the back side and the surface of the doping structure away from the substrate; a doped conductive layer, the doped conductive layer covering the surface of the tunneling layer, the doped conductive layer containing second-type doping ions; a back electrode, the back electrode being located on the back side and electrically connected to the doped conductive layer; wherein, the first-type doping ions are one of N-type doping ions or P-type doping ions, and the second-type doping ions are the other of N-type doping ions or P-type doping ions.

Description

Technical Field

[0001] The present disclosure relates to the field of photovoltaics, and particularly to a solar cell and a method for manufacturing the same. Background Art

[0002] Photovoltaic power generation refers to the conversion of solar energy into electrical energy through the photovoltaic effect of semiconductors. For example, TOPCON (Tunnel Oxide Passivated Contact) cells have received increasing attention due to their good photovoltaic conversion performance.

[0003] TOPCON cells are a type of tunnel oxide passivated contact solar cell technology based on the principle of selective carriers. In TOPCON solar cells, a passivated contact structure is formed on the surface of the substrate to achieve selective carrier transport. The passivated contact structure includes a tunneling layer and a doped conductive layer. Summary of the Invention

[0004] Embodiments of the present disclosure provide a solar cell and a method for manufacturing the same, which can at least improve the hot spot effect of the solar cell.

[0005] According to some embodiments of the present disclosure, on the one hand, an embodiment of the present disclosure provides a solar cell, including: a substrate, the substrate including a front surface and a back surface opposite to each other; a front electrode, the front electrode being located on the front surface; at least one doping structure, the doping structure being located on the back surface, and the doping structure containing first-type doping ions; a tunneling layer, the tunneling layer at least covering the back surface and the surface of the doping structure away from the substrate; a doped conductive layer, the doped conductive layer covering the surface of the tunneling layer, the doped conductive layer containing second-type doping ions; a back electrode, the back electrode being located on the back surface and electrically connected to the doped conductive layer; wherein, the first-type doping ions are one of N-type doping ions or P-type doping ions, and the second-type doping ions are the other of N-type doping ions or P-type doping ions.

[0006] In some embodiments, the substrate includes: a doped region, the doped region being in contact with and facing the doping structure.

[0007] In some embodiments, the substrate includes an edge region and a central region located within the edge region, and the junction depth of the doped region located in the edge region is less than the junction depth of the doped region located in the central region.

[0008] In some embodiments, the doped conductive layer at least covers a part of the side wall of the doping structure.

[0009] In some embodiments, the doping structure includes multiple rows of doping structure groups, each row of the doping structure groups includes a plurality of sub-doping structures, and the sub-doping structures in adjacent rows of the doping structure groups are misaligned with each other.

[0010] According to some embodiments of the present disclosure, on the other hand, an embodiment of the present disclosure further provides a method for manufacturing a battery cell, including: providing a substrate, the substrate includes opposite front and back surfaces; forming at least one doping structure, the doping structure is located on the back surface, and the doping structure contains a first type of doping ions; forming a tunneling layer, the tunneling layer covers at least the back surface and the surface of the doping structure away from the substrate; forming a doped conductive layer, the doped conductive layer covers the surface of the tunneling layer, and the doped conductive layer contains a second type of doping ions; forming a front electrode and a back electrode, the front electrode is located on the front surface, and the back electrode is located on the back surface and is electrically connected to the doped conductive layer; wherein, the first type of doping ions is one of N-type doping ions or P-type doping ions, and the second type of doping ions is the other of N-type doping ions or P-type doping ions.

[0011] In some embodiments, the method for forming the doping structure includes: forming an initial doping structure that covers the entire back surface of the substrate; performing a laser treatment, and converting part of the initial doping structure into the doping structure through the laser treatment, and forming a doped region in the substrate; removing the initial doping structure that has not been treated by the laser, and the remaining initial doping structure constitutes the doping structure.

[0012] In some embodiments, the method for forming the doping structure includes: doping part of the substrate to convert part of the substrate into an initial doping structure; performing a laser treatment to increase the doping depth of the initial doping structure at the position corresponding to the doped region through the laser treatment; etching the initial doping structure to remove the initial doping structure that has not been treated by the laser, and the remaining initial doping structure constitutes the doping structure.

[0013] In some embodiments, after performing the laser treatment, it further includes: performing a heat treatment to increase the junction depth at the position corresponding to the doping structure.

[0014] In some embodiments, the heat treatment includes: a first temperature rising step for rising the temperature of the heat treatment to a first preset temperature; a second temperature rising step for rising the temperature of the heat treatment to a second preset temperature; wherein, the temperature rising rate of the first temperature rising step is greater than the temperature rising rate of the second temperature rising step.

[0015] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages: Among them, a substrate, a front electrode, a tunneling layer, a doped conductive layer, and a back electrode form a TOPCON cell. By forming a doped conductive layer on the back of the TOPCON cell, and the type of doped ions in the doped conductive layer is different from the type of doped ions in the doping structure, a composite contact is formed by directly contacting the doped conductive layer and the doping structure, or a composite contact is achieved through a dielectric layer to form a leakage structure on the back of the cell wafer. The leakage structure is used to reduce the voltage on the opposite sides of the cell wafer, thereby reducing the heating power of the cell wafer, so as to improve the hot spot phenomenon caused by local poor conductivity of the cell wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] One or more embodiments are exemplarily illustrated by the pictures 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; in order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or in the prior art, the drawings required to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 A cross-sectional view of a cell wafer provided by an embodiment of the present disclosure;

[0018] Figure 2 A top view of a cell wafer provided by an embodiment of the present disclosure;

[0019] Figures 3 to 5 A schematic structural diagram corresponding to each step of a method for manufacturing a cell wafer provided by an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] As can be seen from the background art, currently, in TOPCON cells, due to partial occlusion, damage, or inconsistent performance, the working state of some cells is different from that of other cell wafers, resulting in overheating. In severe cases, the cell wafer will be burned out, causing the cell wafer to fail.

[0021] An embodiment of the present disclosure provides a cell. A TOPCon cell is formed by a substrate, a front electrode, a tunneling layer, a doped conductive layer, and a back electrode. By forming a doped conductive layer on the back of the TOPCon cell, and the type of doped ions in the doped conductive layer is different from that in the doping structure, a composite contact is formed by directly contacting the doped conductive layer and the doping structure, or the composite contact is realized through a dielectric layer, so as to form a leakage structure on the back of the cell. The leakage structure is used to reduce the voltage on the opposite sides of the cell, thereby reducing the heating power of the cell, so as to improve the hot spot phenomenon caused by local poor conductivity of the cell.

[0022] In the description of the embodiments of the present disclosure, 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 quantity, specific order, or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "a plurality" is more than two, unless otherwise clearly and specifically defined.

[0023] Referring to "embodiments" herein means that a particular feature, structure, or characteristic described in connection with the embodiments can be included in at least one embodiment of the present disclosure. The phrase does not necessarily refer to the same embodiment at every occurrence in the specification, 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.

[0024] In the description of the embodiments of the present disclosure, the term "and / or" is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: there is A, there is both A and B, and there is B. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0025] In the description of the embodiments of the present disclosure, the term "a plurality" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0026] In the description of the embodiments of the present disclosure, 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. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the embodiments of the present disclosure.

[0027] In the description of the embodiments of the present disclosure, unless otherwise clearly defined 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 also be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific situations.

[0028] In the corresponding drawings of the embodiments of the present disclosure, 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.

[0029] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise specified, 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 "on / located on" another component, it can be "directly on" the other component (that is, located on the surface of the other component and there are no other components between the two), or there can be another component between them. 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 there are no other components located between them.

[0030] The terms used in the description of the various embodiments herein are only for describing specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is also intended to include the plural form, unless the context clearly indicates otherwise. Among them, the component includes components such as layers, films, regions, or plates.

[0031] The following will elaborate on the embodiments of the present disclosure in conjunction with the drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present disclosure, many technical details are presented for the reader to better understand the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed by the present disclosure can still be implemented.

[0032] Reference Figure 1 and Figure 2 , Figure 1 is a cross-sectional view of a cell provided by an embodiment of the present disclosure; Figure 2 is a top view of a doping structure located on the surface of the substrate.

[0033] In some embodiments, the cell may include: a substrate 100, and the substrate 100 includes opposite front surface 110 and back surface 120.

[0034] The cell may further include: a front electrode 101, and the front electrode 101 is located on the front surface 110.

[0035] The cell may further include: at least one doping structure 102, the doping structure 102 is located on the back surface 120, and the doping structure 102 contains first-type doping ions.

[0036] The cell may further include: a tunneling layer 103, and the tunneling layer 103 covers at least the back surface 120 and the surface of the doping structure 102 away from the substrate 100.

[0037] The cell may further include: a doped conductive layer 104, the doped conductive layer 104 covers the surface of the tunneling layer 103, and the doped conductive layer 104 contains second-type doping ions.

[0038] The cell may further include: a back electrode 105, the back electrode 105 is located on the back surface 120 and is electrically connected to the doped conductive layer 104, wherein the first-type doping ions are one of N-type doping ions or P-type doping ions, and the second-type doping ions are the other of N-type doping ions or P-type doping ions.

[0039] The embodiment of the present disclosure provides a cell, which forms a TOPCon cell through the substrate 100, the front electrode 101, the tunneling layer 103, the doped conductive layer 104 and the back electrode 105, and forms a doped conductive layer 104 on the back surface 120 of the TOPCon cell, and the type of doping ions in the doped conductive layer 104 is different from the type of doping ions in the doping structure 102. A composite contact is formed by directly contacting the doped conductive layer and the doping structure, or a composite contact is achieved through a dielectric layer, so as to form a leakage structure on the back surface of the cell, and the leakage structure is used to reduce the voltage on opposite sides of the cell, thereby reducing the heating power of the cell, so as to improve the hot spot phenomenon caused by local poor conductivity of the cell.

[0040] The substrate 100 has opposite front 110 and back 120 surfaces. In some embodiments, if the cell is a single-sided cell, the front 110 of the substrate 100 can be used as the light-receiving surface for receiving incident light, and the back 120 as the backlight surface. In some embodiments, if the cell is a double-sided cell, both the front 110 and the back 120 of the substrate 100 can be used as light-receiving surfaces for receiving incident light. It can be understood that the backlight surface referred to in the embodiments of the present disclosure can also receive incident light, but the degree of receiving incident light is weaker than that of the light-receiving surface, so it is defined as the backlight surface.

[0041] In some embodiments, a texturing process can be performed on at least one of the front 110 or the back 120 surface of the substrate 100 to form a textured surface on at least one of the front 110 or the back 120 surface of the substrate 100. In this way, the absorption and utilization rate of the incident light by the front 110 and the back 120 of the substrate 100 can be enhanced. In some embodiments, the textured surface can be a pyramid textured surface. As a common textured surface, the pyramid textured surface not only reduces the reflectivity of the substrate 100 surface, but also forms a light trap, enhances the absorption effect of the substrate 100 on incident light, and improves the photoelectric conversion efficiency of the cell.

[0042] In some embodiments, the substrate 100 includes: a doped region 106, and the doped region 106 is in contact with and opposite to the doping structure 102. On the one hand, the doped region 106 can also form a part of the leakage current structure of the cell, thereby further improving the hot spot phenomenon of the cell; on the other hand, setting the doped region 106 can also facilitate the formation of the leakage current structure on the back 120 of the cell. For the doping structure 102, it must be formed on the entire back 120 of the substrate 100 during formation, and then a partial coverage effect is formed on the back 120 by removing part of the doping structure 102. Then, when forming the doped region 106 and removing part of the doping structure 102, it can avoid the problem that the entire surface doping structure 102 is removed, resulting in the failure of the leakage current structure, thereby improving the process tolerance.

[0043] In some embodiments, the junction depth of the doped region 106 is 500 nm to 2 μm, such as 700 nm, 900 nm, 1.3 μm, 1.5 μm, or 1.8 μm, etc. For the doped region 106, the deeper the junction depth of the doped region 106, the stronger the leakage current effect of the doped region 106. Similarly, if the junction depth of the doped region 106 is too deep, it will affect the light absorption ability of the cell substrate and cause a large number of carriers to recombine at the corresponding position of the doped region 106, affecting the photoelectric conversion efficiency of the cell. Therefore, by setting the junction depth of the doped region 106 to 500 nm to 2 μm, the hot spot effect of the cell can be improved while avoiding affecting the efficiency of the cell.

[0044] In some embodiments, the substrate 100 includes an edge region and a central region located within the edge region. The junction depth of the doped region 106 in the edge region is less than the junction depth of the doped region 106 in the central region. The edge region of the substrate 100 is the position corresponding to the edge of the substrate 100, and the central region of the substrate 100 is the part located at the center of the substrate 100. Taking a square as an example, the edge region is the partial area adjacent to the edges of the square, and the central region is the partial area enclosed by the edge region. For the edge region of the substrate 100, since it is close to the edge of the cell, an effect similar to corona discharge will occur. Therefore, for the edge region, the leakage effect in the edge region can be weakened by reducing the junction depth of the doped layer in the edge region, so that the leakage effects in the edge region and the central region can be relatively uniform, thereby improving the performance of the cell.

[0045] In some embodiments, the orthographic projection of the doping structure 102 on the surface of the substrate 100 is circular or polygonal. Among them, the polygon can be a regular figure such as a rectangle or a square, etc. For the doping structure 102, setting the orthographic projection of the doping structure 102 on the surface of the substrate 100 to be circular or polygonal can reduce the difficulty of forming the doping structure 102. Especially for the case where the orthographic projection of the doping structure 102 on the surface of the substrate 100 is circular, the leakage efficiency of the circular doping structure 102 is the highest compared with the polygonal doping structure 102. While achieving the same leakage effect, the recombination generated between the circular doping structure 102 and the doped conductive layer 104 is the least.

[0046] In some embodiments, the thickness of the doping structure 102 is 0.01 μm to 1 μm, such as 0.05 μm, 0.2 μm, 0.5 μm, 0.8 μm or 0.95 μm, etc. For the doping structure 102, the thicker the thickness of the doping structure 102, the better the leakage effect brought by the doping structure 102. Similarly, the thicker the thickness of the doping structure 102, the more recombination is generated between the doping structure 102 and the doped conductive layer 104. Therefore, by setting the thickness of the doping structure 102 to be 0.01 μm to 1 μm, the leakage effect of the doping structure 102 can be improved while avoiding affecting the efficiency of the cell.

[0047] In some embodiments, the size of the doping structure 102 is 1 μm to 100 μm. Here, the size can refer to the diameter of a circle, the side length of a square, the long side of a rectangle, or the distance between the two farthest points of the orthographic projection of the doping structure 102 on the surface of the substrate 100. Setting the size of the doping structure 102 to be 1 μm to 100 μm can also improve the leakage effect of the doping structure 102 while avoiding affecting the efficiency of the cell.

[0048] It can be understood that the larger the size of the doping structure 102, the better the leakage effect brought by the doping structure. Similarly, the larger the size of the doping structure 102, a large number of carriers will recombine at the corresponding position of the doping structure 102, which will affect the collection and transmission of carriers in the cell.

[0049] In some embodiments, the ratio of the area of the orthographic projection of the doping structure 102 on the back surface 120 to the area of the back surface 120 is 0.00001% - 0.01%. Similarly, the larger the ratio of the area of the orthographic projection of the doping structure 102 on the back surface 120 to the area of the back surface 120, the better the leakage effect brought by the doping structure 102. The smaller the ratio of the area of the orthographic projection of the doping structure 102 on the back surface 120 to the area of the back surface 120, the lower the ability of the doping structure 102 to affect the cell efficiency. By setting the ratio of the area of the orthographic projection of the doping structure 102 on the back surface 120 to the area of the back surface 120 to be 0.00001% - 0.01%, while improving the leakage effect of the doping structure 102, the photoelectric conversion efficiency of the cell can be avoided from being affected.

[0050] In some embodiments, the doping structures 102 are arranged in an array. By arranging the doping structures 102 in an array, the doping structures 102 can be evenly arranged on the back surface 120 of the cell, so that corresponding leakage structures exist at each position of the cell to improve the hot spot phenomenon of the cell.

[0051] In some embodiments, the doping structure 102 includes multiple rows of doping structure groups 112, and each row of doping structure groups 112 includes multiple sub-doping structures 122. The sub-doping structures 122 in adjacent rows of doping structure groups 112 are offset from each other. In other words, the doping structure 102 is composed of multiple sub-doping structures 122. By setting the sub-doping structures 122 in adjacent rows to be offset from each other, the uniformity of the arrangement of the leakage structures on the back surface 120 of the cell can be further improved, and thus the coverage of the doping structure 102 to improve the hot spot phenomenon can be further increased.

[0052] It can be understood that for the doping structure 102, the ability of a doping structure 102 to improve the hot spot phenomenon is within a certain range. For example, taking the doping structure 102 in the shape of a circle as an example, when the doping structure 102 has leakage, it can improve the hot spot phenomenon in a certain area. When the position where the hot spot phenomenon occurs is at a certain distance from the doping structure 102, the doping structure 102 cannot affect it. Therefore, by setting the sub-doping structures 122 in adjacent rows of doping structure groups 112 in the doping structure 102 to be offset from each other, the range that the doping structure 102 can affect can be increased, and the reliability of the cell can be further improved.

[0053] In some embodiments, the doped structure 102 includes: a silicon substrate layer containing doped ions of the first type, a silicon compound containing doped ions of the first type, or a silicon oxide containing doped ions of the first type. That is to say, the doped structure 102 can be formed by converting part of the substrate 100 into the doped structure 102, or by additionally forming a layer of the doped structure 102 on the surface of the substrate 100. Different materials and formation methods can be selected according to different process requirements.

[0054] In some embodiments, the doped conductive layer 104 covers at least a part of the sidewall of the doped structure 102. That is to say, the doped conductive layer 104 can be in direct contact with the doped structure 102, and a leakage current structure can be formed by direct contact. By setting the doped conductive layer 104 to cover at least a part of the sidewall of the doped structure 102, the leakage current ability of the doped structure 102 can be further improved, and the hot spot effect of the battery cell can be further improved.

[0055] In some embodiments, the tunneling layer 103 covers the surface of the doped structure 102, the doped conductive layer 104 covers the surface of the tunneling layer 103, and the tunneling layer 103 is interposed between the doped structure 102 and the doped conductive layer 104. By spacing the doped conductive layer 104 from the doped structure 102, the influence of the doped structure 102 on the photoelectric conversion efficiency of the battery cell can be avoided, and the performance of the battery cell can be prevented from being affected.

[0056] The doped conductive layer 104 and the tunneling layer 103 constitute a passivation contact structure of the battery cell. The passivation contact structure provides good surface passivation for the back surface 120 of the substrate 100. The tunneling layer 103 can enable majority carriers to tunnel into the doped conductive layer 104 while blocking the recombination of minority carriers, so that the majority carriers are laterally transported in the doped conductive layer 104 and collected by the metal electrode, thereby greatly reducing the metal contact recombination current and improving the open circuit voltage and short circuit current of the solar cell.

[0057] In some embodiments, the battery cell further includes a first passivation layer 107. The first passivation layer 107 covers the surface of the doped conductive layer 104 away from the substrate 100. The first passivation layer 107 can provide good passivation for the back surface 120 of the substrate 100. For example, it can chemically passivate the dangling bonds on the back surface 120 well, saturate the dangling bonds on the back surface 120, reduce the density of defect states on the back surface 120, and inhibit the carrier recombination on the back surface 120.

[0058] In some embodiments, it further includes a front doped layer 108 and a second passivation layer 109. The front doped layer 108 covers the front surface 110 of the substrate 100, the second passivation layer 109 covers the surface of the front doped layer 108 away from the substrate 100, and the front electrode 101 is in contact electrical connection with the front doped layer 108.

[0059] In some embodiments, the front doping layer 108 has the same concentration of doped ions as the doped structure 102 within the doping structure, so that the front doping layer 108 and the doping structure 102 can be formed in the same process step.

[0060] An embodiment of the present disclosure provides a cell. A TOPCon cell is formed by a substrate 100, a front electrode 101, a tunneling layer 103, a doped conductive layer 104, and a back electrode 105. The doped conductive layer 104 is formed on the back surface 120 of the TOPCon cell, and the type of doped ions in the doped conductive layer 104 is different from the type of doped ions in the doped structure 102. A composite contact is formed by directly contacting the doped conductive layer and the doped structure, or a composite contact is achieved through a dielectric layer, so as to form a leakage structure on the back surface of the cell. The leakage structure is used to reduce the voltage across the two opposite sides of the cell, thereby reducing the heating power of the cell, so as to improve the hot spot phenomenon caused by local poor conductivity of the cell.

[0061] Another embodiment of the present disclosure also provides a method for manufacturing a cell. This manufacturing method can be used to form the cell in some or all of the above embodiments. The method for manufacturing a cell provided by another embodiment of the present disclosure will be described below with reference to the accompanying drawings. It should be noted that for the same or corresponding parts in the foregoing embodiments, reference can be made to the corresponding descriptions in the foregoing embodiments, which will not be elaborated below.

[0062] Reference Figures 3 to 5 and Figure 1 , Figures 3 to 5 and Figure 1 are schematic structural diagrams corresponding to each step of a method for manufacturing a cell provided by an embodiment of the present disclosure.

[0063] In some embodiments, the method for manufacturing a cell may include: providing a substrate 100, where the substrate 100 includes an opposite front surface 110 and a back surface 120.

[0064] The method for manufacturing a cell may further include: forming at least one doped structure 102, where the doped structure 102 is located on the back surface 120 and the doped structure 102 contains first-type doped ions.

[0065] The method for manufacturing a cell may further include: forming a tunneling layer 103, where the tunneling layer 103 covers at least the back surface 120 and the surface of the doped structure 102 away from the substrate 100.

[0066] The method for manufacturing a cell may further include: forming a doped conductive layer 104, where the doped conductive layer 104 covers the surface of the tunneling layer 103, and the doped conductive layer 104 contains second-type doped ions.

[0067] The method for manufacturing a solar cell may further include: forming a front electrode 101 and a back electrode 105, where the front electrode 101 is located on the front surface 110, and the back electrode 105 is located on the back surface 120 and is electrically connected to the doped conductive layer 104. Among them, the first type of doped ions is one of N-type doped ions or P-type doped ions, and the second type of doped ions is the other of N-type doped ions or P-type doped ions.

[0068] During the process of forming a TOPCon solar cell, a doped structure 102 is formed on the back surface 120. The doped structure 102 and the doped conductive layer 104 are used to form a leakage channel, and the leakage channel is used to improve the hot spot effect of the solar cell, thereby avoiding damage to the solar cell caused by the hot spot effect, and thus avoiding the failure of the solar cell and improving the reliability of the solar cell.

[0069] Reference Figure 3 , Figure 3 is a morphology of a substrate provided by an embodiment of the present disclosure.

[0070] In some embodiments, after providing the substrate 100, the surface of the substrate 100 may be textured to form a pyramid morphology on the front surface 110 and / or the back surface 120 of the substrate 100, thereby improving the light absorption ability of the substrate 100.

[0071] Reference Figure 4 and Figure 5 , Figure 4 For forming an initial doped structure on the basis of Figure 3 ; Figure 5 For forming a doped structure on the basis of Figure 4 ;

[0072] In some embodiments, the method for forming the doped structure 102 includes: forming an initial doped structure 132, where the initial doped structure 132 covers the entire back surface 120 of the substrate 100; performing laser treatment to convert a part of the initial doped structure 132 into the doped structure 102 through the laser treatment and form a doped region 106 in the substrate 100; removing the initial doped structure 132 that has not been laser-treated, and the remaining initial doped structure 132 constitutes the doped structure 102.

[0073] An initial doped structure 132 is formed by means of whole-surface deposition first. Then, before and after laser treatment, the etching selectivity between the laser-treated part and the non-laser-treated part changes. The non-laser-treated initial doped structure 132 is removed by utilizing the difference in etching selectivity, and the formation of the doped structure 102 is completed. Compared with directly forming the doped structure 102 in a local area of the back surface 120, the method of forming the initial doped structure 132 first and then removing it is beneficial to reducing the process difficulty and is easier to control the position where the doped structure 102 is located, so that the position of the doped structure 102 can be adjusted according to requirements. Moreover, by forming the doped region 106 in the substrate 100, the problem that the entire initial doped structure 132 is removed during the etching process, resulting in the failure of the leakage current channel, can be avoided.

[0074] In some embodiments, the method of forming the doped structure 102 includes: doping a part of the substrate 100 to convert the part of the substrate 100 into an initial doped structure 132; performing laser treatment to increase the doping depth of the initial doped structure 132 at the position corresponding to the doped region 106 through laser treatment; etching the initial doped structure 132 to remove the initial doped structure 132 that is not laser-treated, and the remaining initial doped structure 132 constitutes the doped structure 102. In other words, a part of the substrate 100 is converted into an initial doped structure 132, and then the junction depth of the corresponding position of a part of the initial doped structure 132 is increased through laser treatment, and then at least a part of the initial doped layer that is not laser-treated is removed by etching to form the doped structure 102.

[0075] By converting a part of the substrate 100 into the doped structure 102, the process difficulty of the manufacturing method of the battery cell can also be reduced. Moreover, by laser treatment to deepen the junction depth of the initial doped structure 132 at some positions, it is also convenient to control the position where the doped structure 102 is located.

[0076] It can be understood that by laser treatment to deepen the junction depth of the corresponding position of a part of the initial doped structure 132, a whole-surface etching method can also be adopted when etching the initial doped structure 132. Since the junction depth of the laser-treated position is deeper, after removing the non-laser-treated initial doped structure 132, a part of the laser-treated doped structure 102 will be retained.

[0077] In some embodiments, the initial doped structure 132 can be formed on both the front surface 110 and the back surface 120 of the substrate 100 by means of single-insert diffusion, and then laser treatment is only performed on the back surface 120.

[0078] In some embodiments, after the laser treatment, the following steps are further included: performing a heat treatment to increase the doping junction depth at the corresponding position of the doping structure 102. By further deepening the junction depth at the corresponding position of the doping structure 102, on the one hand, the leakage effect of the doping structure 102 can be further improved; on the other hand, the formation tolerance rate of the manufacturing method of the battery cell can also be improved, thereby avoiding removing the doping structure 102 that needs to be retained while removing the initial doping structure 132, and thus the process stability can be improved.

[0079] In some embodiments, the heat treatment includes: a first temperature-rising step for raising the temperature of the heat treatment to a first preset temperature; a second temperature-rising step for raising the temperature of the heat treatment to a second preset temperature; wherein, the temperature-rising rate of the first temperature-rising step is greater than that of the second temperature-rising step.

[0080] The first temperature-rising step can be a preheating step. By using the first temperature-rising step, the ambient temperature of the battery cell is rapidly raised to the first preset temperature. The second temperature-rising step can be to control the increase of the doping junction depth at the corresponding position of the doping structure 102 while raising the heat treatment to the optimal temperature. For the first temperature-rising step, since it is for presetting, the temperature-rising rate of the first temperature-rising step can be controlled to be faster, thus facilitating the reduction of the process duration of the entire manufacturing method. For the second temperature-rising step, since it is a process of diffusion and temperature increase at the same time, the temperature-rising rate of the second temperature-rising step needs to be controlled to provide the diffusion time of ions, achieving two purposes at the same time, and thus reducing the time of the battery cell in the second temperature-rising step.

[0081] In some embodiments, the first preset temperature is 800°C to 900°C, such as 810°C, 820°C, 840°C, 860°C, 880°C or 890°C, etc., and the second preset temperature is 1000°C to 1200°C, such as 1050°C, 1080°C, 1100°C, 1130°C, 1160°C or 1180°C, etc. By using the first temperature-rising step to rapidly increase the process temperature of the battery cell to 800°C to 900°C, it is convenient to reach the temperature of the subsequent heat treatment. By using the second temperature-rising step to increase the process temperature of the battery cell to 1000°C to 1200°C, at this temperature, it is convenient for the diffusion of carriers in the battery cell, while improving the carrier diffusion speed and avoiding the carriers from diffusing too fast.

[0082] In some embodiments, the heating rate of the first heating step is 10°C / min to 15°C / min, such as 11°C / min, 12°C / min, 13°C / min or 14°C / min, etc., and the heating rate of the second heating step is 3 to 7°C / min, such as 4°C / min, 5°C / min or 6°C / min, etc. Setting the heating rate of the first heating step to 10°C / min to 15°C / min can reduce the temperature of the heat treatment to the first preset temperature while avoiding too rapid change in the ambient temperature of the solar cell, thereby reducing the possibility of abnormalities in the solar cell. Setting the heating rate of the second heating step to 3°C / min to 7°C / min enables the solar cell to complete the diffusion of carriers in a gradually heating environment and avoids the non-uniformity of carrier diffusion caused by too rapid change in the ambient temperature of the solar cell during the diffusion process.

[0083] In some embodiments, the process duration of the heat treatment is 2000 s to 10000 s. For the process duration of the heat treatment, the longer the process duration of the heat treatment, the deeper the doping junction depth corresponding to the initial doping structure 132 will be, and the stronger the leakage performance will be. However, an overly deep doping junction depth will lead to a reduction in the photoelectric conversion efficiency of the formed solar cell. Therefore, by controlling the process duration of the heat treatment to 2000 s to 10000 s, the leakage performance of the initial doping structure 132 can be increased while avoiding affecting the photoelectric conversion efficiency of the solar cell.

[0084] Furthermore, the process duration of the heat treatment is 3000 s to 7000 s. Under this process duration, both the leakage performance brought by the initial doping structure 132 and the influence on the photoelectric conversion efficiency of the solar cell are controlled within a reasonable range.

[0085] In some embodiments, the process parameters of the laser treatment include: the laser type is ultraviolet light, green light or red light, the laser frequency is 100 KHz to 1000 KHz, the laser spot diameter is 1 μm to 100 μm, and the laser energy is 1 W to 500 W. Under these process parameters, it is possible to increase the doping junction depth corresponding to the doping structure 102 while avoiding excessive damage to the doping structure 102 caused by the laser treatment, thereby improving the reliability of the formed solar cell.

[0086] In some embodiments, the process steps for removing the initial doping structure 132 include: a first etching treatment, where the first etching treatment uses hydrofluoric acid with a mass fraction of 30% to 70% to etch the initial doping structure 132; an alkali polishing treatment, where the alkali polishing treatment uses an alkaline solution to clean the initial doping structure 132; and a second etching treatment, where the second etching treatment uses hydrofluoric acid with a mass fraction of 0.5% to 5% to etch the initial doping structure 132.

[0087] The first etching process is used for large-area cleaning of the initial doping structure 132, so as to achieve the purpose of removing the initial doping structure 132. The alkali polishing process is used on the one hand to clean the etching reagent remaining after the first etching process, and on the other hand, it can also be used to form a textured surface on the surface of the substrate 100 exposed after etching the initial doping structure 132. The second etching process can be used to clean the reagent remaining after the alkali polishing process, so as to complete the process step of removing the initial doping structure 132.

[0088] In some embodiments, the alkali polishing process can be composed of potassium hydroxide, hydrogen peroxide, an alkali polishing additive, and deionized water.

[0089] In some embodiments, after the first etching process, it may further include: performing the first trough washing, pre-trough cleaning, and the second trough washing, and then performing the alkali polishing process. After the alkali polishing process, it may further include: the third trough washing, post-trough cleaning, and washing, and then performing the second etching process. After the second etching process, the fourth trough washing may be performed, and then drying is carried out to achieve the purpose of removing the initial doping structure 132.

[0090] It can be understood that trough washing, pre-trough cleaning, post-trough cleaning, and washing are all for removing the substances generated by the reaction and the carriers remaining on the surface of the substrate 100, so as to improve the reliability of the formed solar cell.

[0091] Reference Figure 1 , Figure 1 For forming a tunneling layer, a doped conductive layer, a first passivation layer, and a second passivation layer on the basis of Figure 5 .

[0092] In some embodiments, the tunneling layer 103 and the doped conductive layer 104 can be formed in a back-to-back manner. It should be noted that the back-to-back manner means that the surfaces of two solar cells are closely attached. Taking the formation of the tunneling layer 103 as an example, the fronts 110 of the two solar cells are relatively closely attached, so that the backs 120 of the two solar cells face outward. At this time, the tunneling layer 103 is formed on the exposed surfaces of these two solar cells. It can be understood that since the fronts 110 of these two solar cells are not exposed, the tunneling layer 103 will not be formed on the fronts 110 of the solar cells.

[0093] After forming the tunneling layer 103 and the doped conductive layer 104, the overplating layer located on the front 110 and the overplating layer located on the sidewalls can be etched away. It can be understood that when forming the doped conductive layer 104, an overplating layer will inevitably be formed on the front 110 and an overplating layer will be formed on the sidewalls of the substrate 100. At this time, the overplating layer on the front 110 and the overplating layer on the sidewalls are removed by etching, so as to avoid affecting the performance of the solar cell.

[0094] It can be understood that during the formation of the initial doping layer, since the initial doping layer is also formed on the front surface 110, this part of the initial doping layer located on the front surface 110 can serve as the front doping layer 108.

[0095] In some embodiments, it further includes forming a first passivation layer 107 on the front surface 110 and a second passivation layer 109 on the back surface 120. After forming the first passivation layer 107 and the second passivation layer 109 on the front surface 110 and the back surface 120, the front electrode 101 and the back electrode 105 are formed.

[0096] Those of ordinary skill in the art can understand that the above-described embodiments are specific embodiments for implementing the present disclosure, and in practical applications, various changes can be made to them in form and details without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, the protection scope of the embodiments of the present disclosure should be determined by the scope defined by the claims.

Claims

1. A battery cell, characterized in that, Comprising: A substrate, the substrate comprising an opposite front surface and a back surface; A front electrode, the front electrode being located on the front surface; At least one doping structure, the doping structure being located on the back surface, and the doping structure containing first type doping ions, the doping structure comprising multiple rows of doping structure groups, each row of the doping structure groups comprising multiple sub-doping structures, and the sub-doping structures in adjacent rows of the doping structure groups being misaligned with each other; A tunneling layer, the tunneling layer at least covering the back surface and the surface of the doping structure away from the substrate; A doped conductive layer, the doped conductive layer covering the surface of the tunneling layer, and the doped conductive layer containing second type doping ions; A back electrode, the back electrode being located on the back surface and electrically connected to the doped conductive layer; Wherein, the first type doping ions are one of N-type doping ions or P-type doping ions, and the second type doping ions are the other of N-type doping ions or P-type doping ions.

2. The solar cell according to claim 1, wherein The substrate comprises: a doped region, the doped region being in contact with and facing the doping structure.

3. The solar cell according to claim 2, wherein The substrate comprises an edge region and a central region located within the edge region, and the junction depth of the doped region located in the edge region is less than the junction depth of the doped region located in the central region.

4. The solar cell according to claim 1, wherein The doped conductive layer at least covers a part of the side wall of the doping structure.

5. A manufacturing method of a battery chip, characterized in that, Comprising: Providing a substrate, the substrate comprising an opposite front surface and a back surface; Forming at least one doping structure, the doping structure being located on the back surface, and the doping structure containing first type doping ions, the doping structure comprising multiple rows of doping structure groups, each row of the doping structure groups comprising multiple sub-doping structures, and the sub-doping structures in adjacent rows of the doping structure groups being misaligned with each other; Forming a tunneling layer, the tunneling layer at least covering the back surface and the surface of the doping structure away from the substrate; Forming a doped conductive layer, the doped conductive layer covering the surface of the tunneling layer, and the doped conductive layer containing second type doping ions; Forming a front electrode and a back electrode, the front electrode being located on the front surface, and the back electrode being located on the back surface and electrically connected to the doped conductive layer; Wherein, the first type doping ions are one of N-type doping ions or P-type doping ions, and the second type doping ions are the other of N-type doping ions or P-type doping ions.

6. The manufacturing method of the battery chip according to claim 5, characterized in that, The method for forming the doping structure comprises: Forming an initial doping structure, the initial doping structure covering the entire back surface of the substrate; Performing laser treatment, and converting part of the initial doping structure into the doping structure through the laser treatment, and forming a doped region in the substrate; Removing the initial doping structure that has not been laser-treated, and the remaining initial doping structure constitutes the doping structure.

7. The manufacturing method of the battery chip according to claim 5, characterized in that, The method for forming the doping structure comprises: Doping part of the substrate to convert part of the substrate into an initial doping structure; Performing laser treatment, and increasing the doping depth of the initial doping structure at the position corresponding to the doped region through the laser treatment; Etch the initial doped structure, remove the initial doped structure that has not been laser-treated, and the remaining initial doped structure forms the doped structure.

8. The manufacturing method of the battery chip according to claim 6 or 7, characterized in that, After performing the laser treatment, it further includes: Performing a heat treatment to increase the doping junction depth at the corresponding position of the doped structure.

9. The manufacturing method of the battery chip according to claim 8, characterized in that, The heat treatment includes: A first temperature-rising step for raising the temperature of the heat treatment to a first preset temperature; A second temperature-rising step for raising the temperature of the heat treatment to a second preset temperature; Wherein, the temperature-rising rate of the first temperature-rising step is greater than the temperature-rising rate of the second temperature-rising step.

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