Back contact battery and photovoltaic module

Abstract

The invention provides a back contact battery, which comprises a semiconductor substrate, a first doping layer and a second doping layer, the main body part of the first doping layer and the main body part of the second doping layer are alternately distributed on one side of the backlight surface of the semiconductor substrate, and the conduction types of the first doping layer and the second doping layer are opposite; one part of the second doping layer is overlapped above one part of the first doping layer to form a laminated structure; wherein one or more pits are formed at the laminated structure. The invention also provides a photovoltaic module. According to the back contact cell provided by the invention, one or more pits are formed at the laminated structure, so that the light trapping capability of the back contact cell can be improved.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a back contact cell and a photovoltaic module. Background Art

[0002] A back-contact cell refers to a solar cell with no electrodes on the light-facing side of the cell, and both the positive and negative electrodes are arranged on the back-light side of the cell. This can reduce the shading of the electrodes to the cell, increase the short-circuit current of the cell, and improve the energy conversion efficiency of the cell. During the actual use of the back-contact battery, bird droppings, leaves, dust and other obstructions may fall onto the component, blocking the cell at the corresponding position. When the cell is blocked, the temperature will rise and produce a hot spot effect. If the temperature generated by the hot spot exceeds a certain temperature value, it will cause problems such as delamination of the photovoltaic module, burning of the back panel, and cracking of the glass, which will cause the entire solar cell to be scrapped, and in severe cases may cause a fire risk. However, existing back-contact batteries with anti-hot spot structures have problems such as excessive leakage loss and excessive local heating.

[0003] Therefore, there is a need to provide an improved back contact cell and photovoltaic module to overcome or reduce at least some of the disadvantages existing in the above-mentioned prior art. Summary of the invention

[0004] In a first aspect of the present invention, a back-contact cell is provided, wherein the back-contact cell comprises: a semiconductor substrate, a first doping layer and a second doping layer;

[0005] The main body of the first doping layer and the main body of the second doping layer are alternately distributed on the backlight side of the semiconductor substrate, and the first doping layer and the second doping layer have opposite conductivity types;

[0006] A portion of the second doped layer overlaps a portion of the first doped layer to form a stacked structure; wherein one or more pits are formed at the stacked structure.

[0007] In the back-contact battery of the present invention, a stacked structure is formed by overlapping a portion of the second doped layer on top of a portion of the first doped layer, and one or more pits are formed at the stacked structure. The one or more pits can play a role in trapping light, thereby improving the light trapping ability of the back-contact battery. Furthermore, the pits can also be used as a leakage structure, and when used in conjunction with a conductive doping block, an anti-hot spot structure can be formed, which is beneficial to reducing the risk of hot spots in the back-contact battery.

[0008] Optionally, an upper portion of a sidewall of the pit is surrounded by a first doped layer in the stacked structure.

[0009] Optionally, the lower portion of the sidewall of the pit is surrounded by a semiconductor substrate.

[0010] Optionally, a conductive doping block is disposed in the pit, and the conductive doping block has the same conductivity type as the second doping layer.

[0011] Optionally, a portion of the second doping layer in the stacked structure is recessed downward into the pit to form a conductive doping block.

[0012] Optionally, the conductive doped block and the portion of the first doped layer in the stacked structure surrounding the recess are electrically connected to form a sidewall abutment surface.

[0013] Optionally, a dielectric layer is arranged between the conductive doped block and the portion of the first doped layer in the stacked structure that encloses the recess, and at least one leakage channel is formed in the dielectric layer.

[0014] Optionally, the dielectric layer is interrupted in a partial region, thereby forming a leakage path; or

[0015] The dielectric layer has a thickness of less than or equal to 7 nm in at least a portion of the area, thereby forming a leakage channel.

[0016] Optionally, a portion of the semiconductor substrate surrounding the recess is formed with a prismatic structure.

[0017] Optionally, the longitudinal section of the pit is in an inverted triangle shape, a square shape, an inverted trapezoidal shape, a polygonal shape, or an irregular shape;

[0018] The cross-sectional shape of the pit is a triangle shape, a square shape, a circle shape, an ellipse shape, a trapezoid shape, a polygonal shape, or an irregular shape.

[0019] Optionally, the side surface of the first doped layer in the stacked structure is electrically connected to the second doped layer to form a side butt joint surface.

[0020] Optionally, the recess is disposed adjacent to the side abutment surface.

[0021] Optionally, the total leakage area of ​​the side walls of a single pit is not greater than the total leakage area of ​​the side abutment surfaces.

[0022] In a second aspect of the present invention, a photovoltaic assembly is provided, wherein the photovoltaic assembly comprises:

[0023] A battery string, wherein the battery string is formed by electrically connecting a plurality of the aforementioned back-contact batteries; and

[0024] The encapsulation layer covers the surface of the battery string.

[0025] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Features, advantages, and exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals refer to like elements, and in which:

[0027] Figure 1 1 is a partial schematic diagram of some components of a back contact battery according to an embodiment of the present invention, in which pits are shown.

[0028] Figure 2 It is a partial schematic diagram of some components of a back contact battery according to an embodiment of the present invention.

[0029] Figure 3 yes Figure 1 A partial enlarged schematic diagram of a back-contact battery showing the dielectric layer.

[0030] Figure 4 yes Figure 1 Another enlarged schematic diagram of a back-contacted cell showing the dielectric layer.

[0031] Figure 5 yes Figure 1 Schematic diagram of a partial enlargement of the semiconductor substrate and pit of a back contact battery, showing the edge.

[0032] Figure 6 Schematic diagram of pits with different longitudinal cross-sectional shapes.

[0033] Figure 7 Schematic diagram of pits with different cross-sectional shapes.

[0034] Figure 8 It is a schematic diagram of the distribution relationship between the first doping layer and the second doping layer of the back contact battery according to an embodiment of the present invention.

[0035] Fig. 9 This is another schematic diagram of the distribution relationship between the first doping layer and the second doping layer of the back contact battery according to an embodiment of the present invention.

[0036] Fig.10 Is has Figure 1 SEM image of the back contact battery with pits. DETAILED DESCRIPTION

[0037] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concept of the present invention.

[0038] Various structural schematic diagrams according to embodiments of the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0039] In the context of the present invention, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intermediate layer / element between them. In addition, if a layer / element is "on" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "under" the other layer / element. In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0041] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" and "contacted" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements; it can be a direct contact or an indirect contact through an intermediate medium, it can be an electrical contact, it can be a full-surface contact, it can be a partial contact, it can also be a point contact, etc. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] The present invention provides a back contact battery 100, wherein Figure 1 and Figure 2As shown, the back contact battery 100 includes: a semiconductor substrate 101, a first doping layer 200 and a second doping layer 300; the main body 204 of the first doping layer and the main body 304 of the second doping layer are alternately distributed on the backlight side of the semiconductor substrate 101, and the conductivity types of the first doping layer 200 and the second doping layer 300 are opposite; a portion of the second doping layer 300 is overlapped on top of a portion of the first doping layer 200 to form a stacked structure 600; wherein one or more pits 601 are formed at the stacked structure 600.

[0043] In the back contact cell 100 of the embodiment of the present invention, a stacked structure 600 is formed by overlapping a portion of the second doping layer 300 on top of a portion of the first doping layer 200, and one or more pits 601 are formed at the stacked structure 600. The one or more pits 601 can play a light trapping role, thereby improving the light trapping ability of the back contact cell 100, and can effectively reduce light reflection, increase light scattering and coupling, and improve photoelectric conversion efficiency; further, the one or more pits 601 can also be used as a leakage structure, and when used in conjunction with a conductive doping block 602, an anti-hot spot structure can be formed, which is beneficial to reducing the hot spot risk of the back contact cell 100, that is, reducing the risk of the back contact cell 100 being burned due to local heat concentration.

[0044] The embodiment of the present invention further provides a photovoltaic module (not shown in the figure), wherein the photovoltaic module comprises a battery string formed by electrically connecting the aforementioned back contact batteries 100 and an encapsulation layer covering the surface of the battery string. The photovoltaic module has similar effects to the aforementioned back contact batteries 100.

[0045] The back contact battery 100 according to the embodiment of the present invention will be described in more detail below with reference to the accompanying drawings.

[0046] The back contact cell 100 refers to a solar cell in which the light-facing side 111 of the cell has no electrode, and the positive electrode and the negative electrode are both arranged on the backlight side 112 of the cell. This can reduce the shading of the electrode to the cell, increase the short-circuit current of the cell, and improve the energy conversion efficiency of the cell.

[0047] The distribution relationship between the first doping layer 200 and the second doping layer 300 of the back contact cell 100 can be two kinds, respectively: Figure 8 and Fig. 9 shown.

[0048] It can be understood that, herein, "first doping layer" and "second doping layer" are only for convenience of description, and the first doping layer 200 and the second doping layer 300 can be interchanged in terms of function and setting position. Alternatively, the back contact battery 100 includes: a semiconductor substrate 101, a first doping layer 200 and a second doping layer 300; the main body 204 of the first doping layer and the main body 304 of the second doping layer are alternately distributed on the backlight side of the semiconductor substrate 101, and the first doping layer 200 and the second doping layer 300 have opposite conductivity types; a portion of the first doping layer 200 is overlapped on a portion of the second doping layer 300 to form a stacked structure 600; wherein one or more pits 601 are formed at the stacked structure 600.

[0049] Combine the following Figure 8 A back contact cell 100 according to an embodiment of the present application is described.

[0050] exist Figure 8 In the embodiment, the first doping layer 200 includes a main body 204 of the first doping layer, and the second doping layer 300 includes a main body 304 of the second doping layer. The main body 204 of the first doping layer and the main body 304 of the second doping layer are alternately distributed in strips. There is a spacing region 190 between the main body 204 of the first doping layer and the main body 304 of the second doping layer. Specifically, Figure 8 , the main body 204 of the first doping layer includes only the strip-shaped portion 201 of the first doping layer. The main body 304 of the second doping layer includes only the strip-shaped portion 301 of the second doping layer. The spacing region 190 is formed between the strip-shaped portion 201 of the first doping layer and the strip-shaped portion 301 of the second doping layer. Here, the region where the strip-shaped portion 201 of the first doping layer is located is the first doping region 191, the region where the strip-shaped portion 301 of the second doping layer is located is the second doping region 192, and the spacing region 190 is formed between the first doping region 191 and the second doping region 192.

[0051] The first doping layer 200 may further include an extension portion 203 of the first doping layer, which extends from a local area of ​​the main portion 204 of the first doping layer toward the second doping layer 300 , that is, from a local area of ​​the strip portion 201 of the first doping layer toward the strip portion 301 of the second doping layer 300 .

[0052] The second doping layer 300 may further include an extension portion 303 of the second doping layer, which extends from a local area of ​​the main portion 304 of the second doping layer toward the first doping layer 200, that is, from a local area of ​​the strip portion 301 of the second doping layer toward the strip portion 201 of the first doping layer.

[0053] It should be noted that the extension portion 203 of the first doping layer is usually formed integrally with the main body 204 of the first doping layer, that is, it is extended from a local area of ​​the main body 204 of the first doping layer toward the second doping layer 300. However, the extension portion 203 of the first doping layer can also be formed separately from the main body 204 of the first doping layer, that is, using an additional process, it is independent of the main body 204 of the first doping layer to form a conductive block, wherein the conductive block is structurally connected or partially stacked with the main body 204 of the first doping layer, and the materials can be the same or different, and the conductive type can be the same. The extension portion 303 of the second doping layer is similar to the extension portion 203 of the first doping layer, and will not be repeated here.

[0054] In this way, a portion of the aforementioned second doping layer 300 is overlapped on top of a portion of the first doping layer 200 to form a stacked structure 600, and the "portion of the second doping layer" can be a portion of the main body 304 of the second doping layer, or it can be all or a portion of the extension 303 of the second doping layer, and the "portion of the first doping layer" can be a portion of the main body 204 of the first doping layer, or it can be all or a portion of the extension 203 of the first doping layer.

[0055] Regarding the specific structure of the spacing region 190, in the back contact battery 100 of the embodiment of the present application, the spacing region 190 can be a spacing region disconnected between the main body 204 of the first doping layer and the main body 304 of the second doping layer, and the spacing region 190 can also be a layer spacing region formed by separating the main body 204 of the first doping layer and the main body 304 of the second doping layer by other layer structures such as an insulating layer.

[0056] Regarding the positions of the first doping layer 200 and the second doping layer 300 relative to the semiconductor substrate 101, the first doping layer 200 and the second doping layer 300 may both be formed within the semiconductor substrate 101. Alternatively, the first doping layer 200 and the second doping layer 300 may both be formed on the semiconductor substrate 101. Alternatively, the first doping layer 200 is formed within the semiconductor substrate 101, and the second doping layer 300 is formed on the semiconductor substrate 101. In the aforementioned cases, a portion of the second doping layer 300 may overlap a portion of the first doping layer 200 to form a stacked structure 600. Wherein, in the case where the first doping layer 200 is formed within the semiconductor substrate 101 and the second doping layer 300 is formed on the semiconductor substrate 101, the height of the main body 204 of the first doping layer 200 is generally higher than the height of the main body 304 of the second doping layer 300, and all or a portion of the extension portion 303 of the second doping layer is overlapped on a portion of the main body 204 of the first doping layer 200 to form the stacked structure 600.

[0057] The formation position of the stacked structure 600 may be in the spacing region 190, the first doping region 191, and the second doping region 192. Specifically, when the stacked structure 600 is formed in the spacing region 190, all or part of the extension portion 303 of the second doping layer is overlapped on all or part of the extension portion 203 of the first doping layer; when the stacked structure 600 is formed in the first doping region 191, all or part of the extension portion 303 of the second doping layer is overlapped on part of the strip portion 201 of the first doping layer; when the stacked structure 600 is formed in the second doping region 192, part of the strip portion 301 of the second doping layer is overlapped on all or part of the extension portion 203 of the first doping layer.

[0058] For example, Figure 8 In the figure, at mark 801, the stacked structure 600 is formed at the spacing region 190, where the extension portion 303 of the second doping layer overlaps over the extension portion 203 of the first doping layer; at mark 802, the stacked structure 600 is formed at the first doping region 191, where the extension portion 303 of the second doping layer overlaps over a portion of the strip portion 201 of the first doping layer; at mark 803, the stacked structure 600 is formed at the second doping region 192, where a portion of the strip portion 301 of the second doping layer overlaps over the extension portion 203 of the first doping layer.

[0059] One or more pits 601 may be formed in the stacked structure 600 . Figure 1 6 shows a pit 601 formed at the laminated structure 600. When a plurality of pits 601 are formed at the laminated structure 600, the number of the pits 601 is, for example, 2, 3, 5, 20, etc., and the plurality of pits 601 are arranged at intervals. The specific number of the pits 601 is not limited. Fig.10 Is has Figure 1 SEM image of the back contact cell 100 with the pit 601, where Fig.10 b) Yes Fig.10 a) is a partial enlarged view. Fig.10 In the embodiment, a stacked structure 600 is formed at the first doping region 191 , and a plurality of pits 601 are formed at the stacked structure 600 .

[0060] In some embodiments, in the back contact battery 100 of the embodiment of the present application, the upper part of the sidewall of the pit 601 is surrounded by the first doping layer 200 in the stacked structure 600, such as Figure 1 , Figure 3 and Figure 4 As shown, the pit 601 is a light trapping structure. By setting the upper part of the sidewall of the pit 601 to be surrounded by the first doping layer 200 in the stacked structure 600, the internal reflection of the incident light in the first doping layer 200 can be enhanced, which helps to improve the battery efficiency.

[0061] In some embodiments, in the back contact battery 100 of the present embodiment, the lower part of the sidewall of the pit 601 is surrounded by the semiconductor substrate 101, such as Figure 1 , Figure 3 and Figure 4 As shown, the pit 601 is a light trapping structure. By setting the lower part of the sidewall of the pit 601 to be surrounded by the semiconductor substrate 101, the internal reflection of the incident light in the semiconductor substrate 101 can be enhanced, which helps to improve the battery efficiency.

[0062] In some embodiments, reference Figure 1 In the back contact cell 100 of the embodiment of the present application, the upper sidewall of the pit 601 is surrounded by the first doped layer 200 in the stacked structure 600, and the lower sidewall of the pit 601 is surrounded by the semiconductor substrate 101. Therefore, the pit 601, as a light trapping structure, can enhance the internal reflection of the incident light in the first doped layer 200 and the internal reflection of the incident light in the semiconductor substrate 101, which helps to further improve the cell efficiency.

[0063] refer to Figure 1 , the upper part of the pit 601 is a structure having a first upper opening and a first lower opening, which is connected from top to bottom; and the lower part of the pit 601 is a structure having a second upper opening and a second lower closed end, which is closed at the lower end, wherein the lower end of the pit 601 is closed by the semiconductor substrate 101; the upper and lower parts of the pit 601 are connected by the first lower opening and the second upper opening which are adjacent and oppositely arranged. The specific optional shape of the pit 601 will be described in detail below. The lower end of the pit 601 can usually reach 1 / 2 of the thickness of the semiconductor substrate 101 in the semiconductor substrate 101, such as 1 / 5, 1 / 4, 1 / 3, and 1 / 2. The deeper the lower end of the pit 601 is in the semiconductor substrate 101, the larger the part of the semiconductor substrate 101 that is affected, and the better the enhancement of the internal reflection of the incident light in the semiconductor substrate 101, but the processing difficulty is increased and the processing efficiency is reduced.

[0064] In the back contact cell 100 of the embodiment of the present application, in some embodiments, a conductive doping block 602 may be disposed in the pit 601, and the conductive doping block 602 has the same conductivity type as the second doping layer 300, such as Figure 3 and Figure 4 shown.

[0065] The conductive doping block 602 can fill the entire space of the pit 601, or it can fill only a partial space of the pit 601, for example, only fill the middle and lower space of the pit 601. At this time, only the lower part of the upper part of the side wall of the pit 601 surrounded by the first doping layer 200 in the stacked structure 600 is in contact with the conductive doping block 602. For another example, the conductive doping block 602 extends along the side of the first doping layer 200 that surrounds the upper part of the side wall of the pit 601 and fills the middle and lower space of the pit 601. At this time, the upper part of the side wall of the pit 601 surrounded by the first doping layer 200 in the stacked structure 600 and the lower part of the side wall surrounded by the semiconductor substrate 101 are both in contact with the conductive doping block 602.

[0066] The conductive doping block 602 may be a part of the second doping layer 300, or may be a structure independent of the second doping layer 300, that is, an additional process is used to form a conductive doping block 602 independently of the second doping layer 300, wherein the conductive doping block 602 is structurally connected or partially stacked with the second doping layer 300, and may be the same or different in material and have the same conductivity type. In some embodiments, a part of the second doping layer 300 in the stacked structure 600 is recessed downward into the pit 601 to form the conductive doping block 602, such as Figure 1 By recessing a portion of the second doping layer 300 in the stacked structure 600 downward to form the conductive doping block 602, it is unnecessary to separately process and arrange the conductive doping block 602, thereby improving the processing efficiency.

[0067] In some embodiments, the conductive doped block 602 and the portion of the first doped layer 200 in the stacked structure 600 surrounding the recess 601 are electrically connected to form a sidewall interface 604, such as Figure 1 As shown. By electrically connecting the conductive doping block 602 and the portion of the first doping layer 200 in the stacked structure 600 that encloses the pit 601 and forming a sidewall butt surface 604, a built-in diode with a lower reverse breakdown voltage can be formed at the electrical connection between the conductive doping block 602 and the first doping layer 200, which is beneficial for making the back contact battery 100 have a lower reverse breakdown voltage when it is shielded, reducing the risk of hot spots of the back contact battery 100, that is, reducing the risk of the back contact battery 100 being burned due to local heat concentration; at the same time, by using a plurality of small pits 601 to form an anti-hot spot structure, the leakage points are also dispersed more evenly, further effectively preventing local overheating of the back contact battery 100.

[0068] In some embodiments, a dielectric layer 603 is disposed between the conductive doped block 602 and the portion of the first doped layer 200 in the stacked structure 600 that surrounds the recess 601, and at least one leakage channel 630 is formed in the dielectric layer 603. Figure 3 and Figure 4As shown. By forming at least one leakage channel 630 in the dielectric layer 603, a partial area of ​​the conductive doping block 602 and a partial area of ​​the first doping layer 200 can be electrically connected by means of the leakage channel 630. Since the conductive doping block 602 and the first doping layer 200 have opposite doping types, a built-in diode with a lower reverse breakdown voltage can be formed between the conductive doping block 602 and the first doping layer 200 by manufacturing a local leakage point, thereby making the back contact battery 100 have a higher anti-burning ability when it is blocked, and reducing the risk of hot spots of the back contact battery 100. In addition, the dielectric layer 603 can achieve physical structural separation of the conductive doping block 602 and the first doping layer 200, and by controlling the thickness of the dielectric layer 603, for example, setting the thickness of the dielectric layer 603 to be greater than or equal to 13 nm, the dielectric layer 603 itself has certain electrical insulation or semi-insulating properties. Therefore, the portion of the dielectric layer 603 where the leakage channel 630 is not provided can achieve electrical isolation between partial areas of the conductive doping block 602 and partial areas of the first doping layer 200, effectively reducing the direct transmission and recombination of carriers collected by the conductive doping block 602 and the first doping layer 200, thereby effectively controlling the leakage loss of the back contact battery 100, so that the back contact battery 100 has good working performance. It can be seen that in the back-contact battery 100 of the embodiment of the present invention, the leakage loss of the back-contact battery 100 in the forward voltage region can be effectively controlled by the insulating or semi-insulating characteristics of the portion of the dielectric layer 603 where the leakage channel 630 is not set. At the same time, the hot spot risk of the back-contact battery 100 is reduced by means of the leakage channel 630 set in the dielectric layer 603, and the controllability of leakage and electrical isolation is achieved, which is beneficial to adjusting the reverse breakdown voltage and working efficiency corresponding to the back-contact battery 100 to achieve a balance.

[0069] In some embodiments, the dielectric layer 603 is interrupted in a portion of the area, thereby forming a leakage channel 630. Figure 3 As shown, the dielectric layer 603 may be interrupted at the leakage channel 630. At this time, the thickness of the portion of the dielectric layer 603 where the leakage channel 630 is provided is 0, and the leakage channel 630 penetrates the dielectric layer 603.

[0070] In other embodiments, Figure 4As shown, the thickness of the dielectric layer 603 in at least part of the region is less than or equal to 7nm, thereby forming a leakage channel 630. The thickness of the dielectric layer 603 in at least part of the region may be, for example, 0.0001nm, 1nm, 2nm, 3nm, 4nm, 5nm, 6nm or 7nm. By controlling the thickness of the dielectric layer 603 at the leakage channel 630 to be less than 7nm, the electrical transmission performance of the dielectric layer 603 at the leakage channel 630 is better, and electrical connection can be achieved, thereby achieving leakage at the leakage channel 630, so that the back contact battery 100 has anti-hot spot capability; by controlling the specific thickness of the dielectric layer 603 in the partial region of the leakage channel 630, the leakage degree between the conductive doping block 602 and the first doping layer 200 can be regulated, and the leakage size can be regulated, thereby achieving the controllability of leakage and electrical isolation, which is conducive to adjusting the reverse breakdown voltage and working efficiency corresponding to the back contact battery 100 to achieve a balance.

[0071] refer to Figure 5 In some embodiments, the portion of the semiconductor substrate 101 surrounding the pit 601 is formed with a prismatic structure 110. By providing the portion of the semiconductor substrate 101 surrounding the pit 601 with a prismatic structure 110, the light trapping capability can be further improved, and the photoelectric conversion efficiency can be improved. Figure 5 Only a partial portion of the lower part of the semiconductor substrate 101 surrounding the recess 601 is shown. The specific arrangement of the prismatic structure 110 is not limited. Figure 5 In a), the prismatic structure 110 is arranged at an angle to the thickness direction of the semiconductor substrate 101; Figure 5 b), the prismatic structure 110 is arranged parallel to the thickness direction of the semiconductor substrate 101. The number of the prismatic structure 110 can be one or more, and usually a plurality of prismatic structures 110 are formed in a continuous or intermittent manner around the circumference of the portion of the semiconductor substrate 101 enclosing the recess 601.

[0072] Possible shapes of the pit 601 in the stacked structure 600 are described below.

[0073] In some embodiments, Figure 6 As shown, the longitudinal cross-section of the pit 601 can be an inverted triangle, a square, an inverted trapezoid, a polygon, or an irregular shape.

[0074] Herein, when describing a certain shape, it includes both the standard shape and similar shapes that are substantially similar to the shape, for example, an inverted triangle shape includes a standard inverted triangle shape and a substantially inverted triangle shape, a square shape includes a standard square shape and a substantially square shape, an inverted trapezoid shape includes a standard inverted trapezoid shape and a substantially inverted trapezoid shape, and a polygonal shape includes a standard polygonal shape and a substantially polygonal shape. For a special-shaped shape, it is an irregular shape that is greatly different from a standard common regular shape and cannot be classified.

[0075] Figure 6 a), the longitudinal cross-section of the pit 601 is an inverted triangle; Figure 6 b), the longitudinal cross-section of the pit 601 is a square shape; Figure 6 c), the longitudinal cross-section of the pit 601 is an inverted trapezoidal shape; Figure 6 d), the longitudinal cross-section of the pit 601 is a polygonal shape; Figure 6 e) and Figure 6 f), the longitudinal cross-section of the pit 601 is a special shape, wherein: Figure 6 e), the longitudinal cross-section of the pit 601 is in the shape of a "+", Figure 6 f), the longitudinal cross-sectional shape of the pit 601 is a “T” shape. It can be understood that when there are multiple pits 601 in a single stacked structure 600, the longitudinal cross-sectional shapes of the multiple pits 601 can be the same, different, or partially the same and partially different.

[0076] Figure 6 e), assuming that in the “+” shape, the portion above the dotted line in the figure is the upper portion of the pit 601 surrounded by the first doped layer 200 in the stacked structure 600, and the portion below the dotted line in the figure is the lower portion of the pit 601 surrounded by the semiconductor substrate 101. In this case, compared to Figure 6 b) has a square shape, and the surface area of ​​the upper side wall of the pit 601 is increased, thereby increasing the setting volume of the conductive doping block 602 in the pit 601 and increasing the contact area of ​​the leakage channel of the side wall docking surface 604, which is beneficial to improving the anti-hot spot effect.

[0077] Figure 6 f), assuming that in the "T" shape, the portion above the dotted line in the figure is the upper portion of the pit 601 surrounded by the first doped layer 200 in the stacked structure 600, and the portion below the dotted line in the figure is the lower portion of the pit 601 surrounded by the semiconductor substrate 101. In this case, compared to Figure 6 b) The square shape can enhance the internal reflection of the incident light in the semiconductor substrate 101 due to the presence of the terrace portion at the dotted line.

[0078] In some embodiments, Figure 7As shown, the cross-sectional shape of the dimple 601 is triangular, square, circular, elliptical, trapezoidal, polygonal, or irregular.

[0079] Figure 7 a), the cross-sectional shape of the pit 601 is a triangle; Figure 7 b), the cross-sectional shape of the pit 601 is a square shape; Figure 7 c), the cross-sectional shape of the pit 601 is circular; Figure 7 d), the cross-sectional shape of the pit 601 is an elliptical shape; Figure 7 e), the cross-sectional shape of the pit 601 is a trapezoid; Figure 7 f), the cross-sectional shape of the pit 601 is a polygonal shape; Figure 7 g) and Figure 7 h), the cross-sectional shape of the pit 601 is a special shape. It can be understood that when there are multiple pits 601 in a single laminated structure 600, the cross-sectional shapes of the multiple pits 601 can be the same, different, or partially the same and partially different.

[0080] In some embodiments, Figure 1 As shown, the side surface of the first doping layer 200 in the stacked structure 600 is electrically connected to the second doping layer 300 , and a side interface 400 is formed.

[0081] In the back contact battery 100 of the embodiment of the present invention, by overlapping a portion of the second doping layer 300 on top of a portion of the first doping layer 200, the two are electrically connected and form a side docking surface 400, a built-in diode with a lower reverse breakdown voltage can be formed at the electrical connection between the stacked structure 600 and the second doping layer 300, which is beneficial for the back contact battery 100 to have a lower reverse breakdown voltage when it is blocked, reducing the hot spot risk of the back contact battery 100, that is, reducing the risk of the back contact battery 100 being burned due to local heat concentration; the side docking surface 400 and the side wall docking surface 604 at the pit 601 can act synergistically, and a portion of the leakage current collected by the side wall docking surface 604 at the pit 601 can be dispersed to the side docking surface 400 of the stacked structure 600, thereby accelerating the transmission speed of the leakage current, which is beneficial for further improving the anti-hot spot effect.

[0082] A single stacked structure 600 may include one or more side butt joints 400. A single "battery unit" may be a whole cell, a half cell, or other specifications of cells.

[0083] In some embodiments, the pit 601 is disposed close to the side docking surface 400. By disposing the pit 601 close to the side docking surface 400, the sidewall docking surface 604 can be disposed close to the side docking surface 400, so that the transmission path of the leakage current can be further shortened, and the anti-hot spot effect can be further improved. Generally, one or more pit 601 structures are disposed in the half area of ​​the laminated structure 600 close to the side docking surface 400; and / or, the number of pits 601 disposed in the half area of ​​the laminated structure 600 close to the side docking surface 400 is greater than the number of pits 601 disposed in the half area of ​​the laminated structure 600 away from the side docking surface 400.

[0084] In some embodiments, the total leakage area of ​​the sidewalls of a single pit 601 is not greater than the total leakage area of ​​the side interface 400. In other words, the total leakage area of ​​the sidewall interface 604 is not greater than the total leakage area of ​​the side interface 400. The side interface 400 is the main anti-hot spot structure, and the sidewall interface 604 at the pit 601 is an auxiliary anti-hot spot structure. Usually, the total leakage area of ​​the sidewalls of a single pit 601 is not greater than the total leakage area of ​​the side interface 400; and, compared with the sidewall interface 604 formed by butt joint, the reliability of the electrical connection at the side interface 400 formed by overlap is higher.

[0085] The formation position of the side butt joint 400 is different according to the formation position of the stacked structure 600, and can be formed in the spacing region 190, the first doping region 191, the second doping region 192, the junction of the spacing region 190 and the first doping region 191, and the junction of the spacing region 190 and the second doping region 192. Specifically, when the stacked structure 600 is formed in the spacing region 190, the side butt joint 400 can be formed in the spacing region 190, the junction of the spacing region 190 and the first doping region 191, and the junction of the spacing region 190 and the second doping region 192; when the stacked structure 600 is formed in the first doping region 191, the side butt joint 400 can be formed in the first doping region 191, the spacing region 190 and the first doping region 191; when the stacked structure 600 is formed in the second doping region 192, the side butt joint 400 can be formed in the second doping region 192, the spacing region 190 and the second doping region 192.

[0086] Regarding the contact mode between a portion of the first doping layer 200 and a portion of the second doping layer 300, a portion of the first doping layer 200 and a portion of the second doping layer 300 may be in direct contact with each other to form a side butt joint surface 400; a portion of the first doping layer 200 and a portion of the second doping layer 300 may also be in indirect contact with each other to form a side butt joint surface 400, that is, other layer structures may be provided between a portion of the first doping layer 200 and a portion of the second doping layer 300 as needed, and it is sufficient that a portion of the first doping layer 200 and a portion of the second doping layer 300 can be electrically butted against each other.

[0087] Combine the following Fig. 9 A back contact cell 100 according to an embodiment of the present application is described.

[0088] exist Fig. 9 In the embodiment, the first doping layer 200 includes a main body 204 of the first doping layer, and the second doping layer 300 includes a main body 304 of the second doping layer. The main body 204 of the first doping layer and the main body 304 of the second doping layer are alternately distributed in a forked shape. There is a spacing region 190 between the main body 204 of the first doping layer and the main body 304 of the second doping layer. Specifically, Fig. 9 In the embodiment, the main body 204 of the first doping layer includes a strip portion 201 of the first doping layer and a connecting portion 202 of the first doping layer, wherein the connecting portion 202 of the first doping layer is used to connect multiple strip portions 201 of the first doping layer. The second doping layer 300 includes a strip portion 301 of the second doping layer and a connecting portion 302 of the second doping layer, wherein the connecting portion 302 of the second doping layer is used to connect multiple strip portions 301 of the second doping layer. The region where the strip portion 201 of the first doping layer is located is the first doping region 191, the region where the strip portion 301 of the second doping layer is located is the second doping region 192, the region where the connecting portion 202 of the first doping layer is located is the third doping region 193, and the region where the connecting portion 302 of the second doping layer is located is the fourth doping region 194. In this case, the spacing region 190 can be: formed between the strip portion 201 of the first doping layer and the strip portion 301 of the adjacent second doping layer, that is, between the first doping region 191 and the second doping region 192; formed between the strip portion 201 of the first doping layer and the connecting portion 302 of the adjacent second doping layer, that is, between the first doping region 191 and the fourth doping region 194; formed between the connecting portion 202 of the first doping layer and the strip portion 301 of the adjacent second doping layer, that is, between the third doping region 193 and the second doping region 192.

[0089] The first doping layer 200 may further include an extension portion 203 of the first doping layer, the extension portion 203 of the first doping layer extending from a local area of ​​the main body portion 204 of the first doping layer toward the second doping layer 300, that is, extending from the strip portion 201 of the first doping layer, or the connecting portion 202 of the first doping layer toward the second doping layer 300. Specifically, the extension portion 203 of the first doping layer extends from a local area of ​​the strip portion 201 of the first doping layer toward the strip portion 301 of the second doping layer or the connecting portion 302 of the second doping layer, or extends from the entire or local area of ​​the connecting portion 202 of the first doping layer toward the strip portion 301 of the second doping layer.

[0090] The second doping layer 300 may further include an extension portion 303 of the second doping layer, and the extension portion 303 of the second doping layer extends from a local area of ​​the main body portion 304 of the second doping layer toward the first doping layer 200, that is, extends from the strip portion 301 of the second doping layer, or the connecting portion 302 of the second doping layer toward the first doping layer 200. Specifically, the extension portion 303 of the second doping layer extends from a local area of ​​the strip portion 301 of the second doping layer toward the strip portion 201 of the first doping layer or the connecting portion 202 of the first doping layer, or extends from the entire or local area of ​​the connecting portion 302 of the second doping layer toward the strip portion 201 of the first doping layer.

[0091] and Figure 8 similar, Fig. 9 The extension portion 203 of the first doping layer is usually formed integrally with the main body portion 204 of the first doping layer, but the extension portion 203 of the first doping layer can also be formed separately from the main body portion 204 of the first doping layer. The extension portion 303 of the second doping layer is similar to the extension portion 203 of the first doping layer, and will not be described in detail here.

[0092] In this way, a portion of the second doping layer 300 overlaps a portion of the first doping layer 200 to form a stacked structure 600, and "a portion of the second doping layer" may be a portion of the strip portion 301 of the second doping layer, or may be all or a portion of the connecting portion 302 of the second doping layer, or may be all or a portion of the extending portion 303 of the second doping layer, and "a portion of the first doping layer" may be a portion of the strip portion 201 of the first doping layer, or may be all or a portion of the connecting portion 202 of the first doping layer, or may be all or a portion of the extending portion 203 of the first doping layer. It should be understood that usually a portion of the second doping layer 300 overlaps a portion of the first doping layer 200 in an adjacent position to form the stacked structure 600.

[0093] The stacked structure 600 may be formed in the spacing region 190 , the first doping region 191 , the second doping region 192 , the third doping region 193 , and the fourth doping region 194 . Specifically, when the stacked structure 600 is formed in the spacing region 190, all or a part of the extension portion 303 of the second doping layer is overlapped and formed over all or a part of the extension portion 203 of the first doping layer; when the stacked structure 600 is formed in the first doping region 191, all or a part of the extension portion 303 of the second doping layer is overlapped and formed over a part of the strip portion 201 of the first doping layer; when the stacked structure 600 is formed in the second doping region 192, a part of the strip portion 301 of the second doping layer is overlapped and formed over all or a part of the extension portion 203 of the first doping layer; when the stacked structure 600 is formed in the third doping region 193, all or a part of the extension portion 303 of the second doping layer is overlapped and formed over all or a part of the connection portion 202 of the first doping layer; when the stacked structure 600 is formed in the fourth doping region 194, all or a part of the connection portion 302 of the second doping layer is overlapped and formed over all or a part of the extension portion 203 of the first doping layer.

[0094] For example, Fig. 9 In the stacked structure 600, at the mark 901, the extension portion 303 of the second doping layer (the extension portion 303 of the second doping layer is specifically formed by extending from the strip portion 301 of the second doping layer toward the connecting portion 202 of the first doping layer) overlaps the extension portion 203 of the first doping layer (the extension portion 203 of the first doping layer is specifically formed by extending from the connecting portion 202 of the first doping layer toward the strip portion 301 of the second doping layer) at the spacing region 190; at the mark 902, the stacked structure 600 may be at the first doping region 191, the extension portion 303 of the second doping layer overlaps the extension portion 203 of the first doping layer (the extension portion 203 of the first doping layer is specifically formed by extending from the connecting portion 202 of the first doping layer toward the strip portion 301 of the second doping layer). The portion 303 of the second doping layer (the extension portion 303 of the second doping layer is specifically formed by extending from the strip portion 301 of the second doping layer toward the strip portion 201 of the first doping layer) is overlapped over a portion of the strip portion 201 of the first doping layer; at the mark 903, the stacked structure 600 can be formed at the first doping region 191, the extension portion 303 of the second doping layer (the extension portion 303 of the second doping layer is specifically formed by extending from the connecting portion 302 of the second doping layer toward the strip portion 201 of the first doping layer) is overlapped over a portion of the strip portion 201 of the first doping layer.

[0095] The specific structure of the spacing region 190, the number of the pits 601, the shape of the pits 601, the formation position of the side interface 400, the position of the first doping layer 200 and the second doping layer 300 relative to the semiconductor substrate 101, the contact method between a part of the first doping layer 200 and a part of the second doping layer 300, etc. Figure 8The back contact cell 100 in FIG. 1 is similar in part, and only some features are shown below.

[0096] In some embodiments, in the back contact battery 100 of the embodiment of the present application, the upper part of the sidewall of the pit 601 is surrounded by the first doping layer 200 in the stacked structure 600. The effect is similar to the above, and will not be repeated here.

[0097] In some embodiments, in the back contact battery 100 of the embodiment of the present application, the lower part of the sidewall of the pit 601 is surrounded by the semiconductor substrate 101. The effect is similar to the above, and will not be repeated here.

[0098] In some embodiments, reference Figure 1 In the back contact cell 100 of the embodiment of the present application, the upper sidewall of the pit 601 is surrounded by the first doping layer 200 in the stacked structure 600, and the lower sidewall of the pit 601 is surrounded by the semiconductor substrate 101. The effect is similar to the above, and will not be repeated here.

[0099] In some embodiments, a conductive doping block 602 may be disposed in the pit 601, and the conductive doping block 602 has the same conductivity type as the second doping layer 300. The effect is similar to the above, and will not be described in detail here.

[0100] In some embodiments, the conductive doped block 602 and the portion of the first doped layer 200 in the stacked structure 600 surrounding the pit 601 are electrically connected to form a sidewall interface 604. The effect is similar to the above, and will not be repeated here.

[0101] In some embodiments, a dielectric layer 603 is disposed between the conductive doped block 602 and the portion of the first doped layer 200 in the stacked structure 600 surrounding the pit 601, and at least one leakage channel 630 is formed in the dielectric layer 603. The effect is similar to the above, and will not be repeated here.

[0102] In some embodiments, the dielectric layer 603 is interrupted in a portion of the area, thereby forming a leakage channel 630. Figure 3 As shown, the dielectric layer 603 may be interrupted at the leakage path 630. The effect is similar to the above, and will not be described in detail here.

[0103] In other embodiments, Figure 4 As shown, the thickness of the dielectric layer 603 in at least a part of the region is less than or equal to 7 nm, thereby forming a leakage channel 630. The effect is similar to the above, and will not be repeated here.

[0104] In some embodiments, Figure 1As shown, the side surface of the first doping layer 200 in the stacked structure 600 is electrically connected to the second doping layer 300, and forms a side interface 400. The effect is similar to the above, and will not be repeated here.

[0105] As for the formation position of the side docking surface 400, similar to the foregoing, it can be at the spacing region 190, the first doping region 191, the second doping region 192, the third doping region 193, the fourth doping region 194, the junction of the spacing region 190 and the first doping region 191 (which can also be called the junction of the spacing region 190 and the strip portion 201 of the first doping layer), the junction of the spacing region 190 and the second doping region 192 (which can also be called the junction of the spacing region 190 and the strip portion 301 of the second doping layer), the junction of the spacing region 190 and the third doping region 193 (which can also be called the junction of the spacing region 190 and the extension 203 of the first doping layer), the junction of the spacing region 190 and the fourth doping region 194 (which can also be called the junction of the spacing region 190 and the connecting portion 302 of the second doping layer), etc., which will not be elaborated here.

[0106] Combine the following Figure 1 and Figure 2 , the overall structure of the back contact battery 100 of the embodiment of the present application is described.

[0107] like Figure 1 and Figure 2 As shown, the back contact cell 100 includes: a semiconductor substrate 101, a first doping layer 200 and a second doping layer 300; the main body 204 of the first doping layer and the main body 304 of the second doping layer are alternately distributed on the backlight side of the semiconductor substrate 101, and the first doping layer 200 and the second doping layer 300 have opposite conductivity types; the extension 303 of the second doping layer is overlapped on the main body 204 of the first doping layer to form a stacked structure 600; wherein one or more pits 601 are formed at the stacked structure 600. The longitudinal cross-section shape of the pit 601 is an inverted triangle shape.

[0108] Figure 1 The back contact battery 100 shown may also include a first dielectric layer 131 located between the first doping layer 200 and the semiconductor substrate 101, a second dielectric layer 132 located between the second doping layer 300 and the semiconductor substrate 101, an insulating layer 150 located between the extension portion 303 of the second doping layer and the main portion 204 of the first doping layer in the stacked structure 600, a surface passivation layer 140 located above the first doping layer 200 and the second doping layer 300, a first electrode 121, and a second electrode 122.

[0109] It should be noted that, in terms of the specific electrode structure of the positive electrode and the negative electrode, the back contact battery 100 of the embodiment of the present invention may be a "back contact battery without a main grid". In this case, the electrode structure in the back contact battery only includes a plurality of collector electrodes (a first electrode 121 and a second electrode 122). The collector electrodes may also be referred to as fine grid lines. The plurality of collector electrodes may extend along a first direction and be spaced apart along a second direction. Alternatively, the back contact battery 100 of the embodiment of the present invention may also be a "back contact battery with a main grid. In this case, the back contact battery includes a plurality of collector electrodes and a plurality of bus structures (not shown in the figure). The bus structures may also be referred to as bus electrodes. The bus structures are spaced apart along a first direction and extend along a second direction, and are electrically coupled to collector electrodes of the same conductivity type as themselves. The bus structure may be a structure extending over the entire cell or a structure extending over only a portion of the cell.

[0110] The materials of the various layers and electrodes of the back contact battery 100 of the embodiment of the present invention can refer to any material in the prior art that can be used to prepare the back contact battery 100. The materials of each layer are briefly described below.

[0111] The semiconductor substrate may be a silicon substrate. The silicon substrate may be N-type or P-type silicon with a thickness of 30-500 microns. The backlight surface and the light-facing surface of the semiconductor substrate may be flat. Alternatively, the light-facing surface of the semiconductor substrate may also be a velvet surface.

[0112] The conductivity type of the first doped layer can be N-type, in which case the conductivity type of the second doped layer is P-type; or, the conductivity type of the first doped layer can also be P-type, in which case the conductivity type of the second doped layer is N-type. For the specific materials of the first doped layer and the second doped layer, the N-type doped layer can be one or more of single crystal silicon, polycrystalline silicon, amorphous silicon, microcrystalline silicon, nanocrystalline silicon and silicon oxide, and its N-type doping element can be one or more of carbon, nitrogen, phosphorus, arsenic, antimony, bismuth, oxygen, sulfur, selenium, and tellurium; the P-type doped semiconductor layer can be one or more of single crystal silicon, polycrystalline silicon, amorphous silicon, microcrystalline silicon, nanocrystalline silicon and silicon oxide, and its P-type doping element can be one or more of boron, aluminum, gallium, indium, thallium, carbon, and nitrogen. The thickness of the first doped layer and the second doped layer can be set as needed, for example, 3-3000nm.

[0113] The first dielectric layer and the second dielectric layer can be one or more of oxide, nitride, oxynitride, halide, carbide, silicon, and their thickness can be set as needed, for example, 0-10nm. Preferably, the dielectric layer, the first dielectric layer and the second dielectric layer can be one or more of silicon oxide, aluminum oxide, titanium oxide, niobium oxide, boron oxide, gallium oxide, tin oxide, hafnium oxide, tantalum oxide, silicon nitride, silicon oxynitride, silicon carbide, lithium fluoride, magnesium fluoride, amorphous silicon, microcrystalline silicon, nanocrystalline silicon, etc.

[0114] The insulating layer may be one or more of oxide, nitride, oxynitride, halide, carbide, silicon, and its thickness may be set as required, for example, 0-5000 nm. Preferably, the insulating layer may be one or more of phosphosilicate glass, borosilicate glass, aluminosilicate glass, gallium silicon glass, silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, silicon carbide, amorphous silicon, etc.

[0115] The surface passivation layer can be one or more of oxide, nitride, oxynitride, halide, carbide, silicon, and its thickness can be set as needed, for example, 0-1000nm. Preferably, the surface passivation layer can be one or more of silicon oxide, aluminum oxide, titanium oxide, niobium oxide, boron oxide, gallium oxide, tin oxide, hafnium oxide, tantalum oxide, indium oxide, tungsten oxide, zinc oxide, silicon nitride, silicon oxynitride, silicon carbide, lithium fluoride, magnesium fluoride, amorphous silicon, microcrystalline silicon, nanocrystalline silicon, etc.

[0116] The method for preparing the back contact battery 100 of the embodiment of the present invention can refer to any method in the prior art that can be used to prepare the back contact battery 100, and is not limited here. The pit structure can be obtained by using existing laser etching or other methods.

[0117] Unless there are technical obstacles or contradictions, the various technical features disclosed in this application can be freely combined to form additional embodiments, and these additional embodiments are all within the protection scope of this application.

[0118] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "an example", "some embodiments", or "preferred embodiment" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0119] The embodiments of the present invention are described in detail above. However, aspects of the present invention are not limited to the above embodiments. Various modifications and substitutions may be applied to the above embodiments without departing from the scope of the present invention.

Claims

1. A back contact battery, wherein: The back contact cell comprises: a semiconductor substrate, a first doping layer and a second doping layer; The main body of the first doping layer and the main body of the second doping layer are alternately distributed on the backlight side of the semiconductor substrate, and the first doping layer and the second doping layer have opposite conductivity types; A portion of the second doping layer overlaps a portion of the first doping layer to form a stacked structure; wherein one or more pits are formed at the stacked structure.

2. The back contact cell according to claim 1, wherein: The upper portion of the sidewall of the pit is surrounded by the first doping layer in the stacked structure.

3. The back contact cell according to claim 1, wherein: The lower part of the side wall of the pit is surrounded by the semiconductor substrate.

4. The back contact cell according to claim 1, wherein: A conductive doping block is disposed in the pit, and the conductive doping block has the same conductivity type as the second doping layer.

5. The back contact cell according to claim 4, wherein: A portion of the second doping layer in the stacked structure is recessed downward into the pit to form the conductive doping block.

6. The back contact cell according to claim 4, wherein: The conductive doping block and a portion of the first doping layer in the stacked structure surrounding the pit are electrically connected to form a sidewall abutment surface.

7. The back contact cell according to claim 4, wherein: A dielectric layer is arranged between the conductive doping block and a portion of the first doping layer in the stacked structure surrounding the pit, and at least one leakage channel is formed in the dielectric layer.

8. The back contact cell according to claim 7, wherein: The dielectric layer is interrupted in a partial area, thereby forming the leakage path; or The thickness of the dielectric layer in at least a portion of the region is less than or equal to 7 nm, thereby forming the leakage channel.

9. The back contact cell according to claim 1, wherein: The portion of the semiconductor substrate surrounding the pit is formed with a prismatic structure.

10. The back contact cell according to claim 1, wherein: The longitudinal cross-section of the pit is in an inverted triangle, a square, an inverted trapezoid, a polygon, or an irregular shape; The cross-sectional shape of the pit is triangular, square, circular, elliptical, trapezoidal, polygonal, or irregular.

11. The back contact cell according to claim 1, wherein: The side surface of the first doping layer in the stacked structure is electrically connected to the second doping layer to form a side butting surface.

12. The back contact cell according to claim 11, wherein: The recess is arranged close to the side abutment surface.

13. The back contact cell according to claim 11, wherein: The total leakage area of ​​the side walls of a single pit is not greater than the total leakage area of ​​the side butt surface.

14. A photovoltaic module, wherein: The photovoltaic module comprises: A battery string, the battery string being formed by electrically connecting a plurality of back-contact batteries according to any one of claims 1 to 13; and A packaging layer covers a surface of the battery string.

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