Back-contact cell, cell string, cell module and photovoltaic system

Abstract

The present application applies to the technical field of solar cells. Provided are a back-contact cell (100), a cell string (200), a cell module (300), and a photovoltaic system (400). In the back-contact cell (100), a first trench (121) and a protrusion (122) arranged in a first direction are formed on a back surface (12) of a silicon substrate (10); a first doped layer (20) is stacked on the protrusion (122), the first doped layer (20) being a P-type doped layer, and the first doped layer (20) comprising a first sub-doped layer (21) and a second sub-doped layer (22) that are stacked; a first insulating layer (40) is stacked on the second sub-doped layer (22); a second doped layer (30) is stacked in the first trench (121), the second doped layer (30) being an N-type doped layer; and a conductive contact structure (50) comprises a protruding portion (51); only part of the first doped layer (20) and only part of the second doped layer (30) are each electrically connected to at least the protruding portion (51); the thickness of the protruding portion (51) in the direction of thickness is greater than the total thickness of the protrusion (122), the first doped layer (20), and the first insulating layer (40).

Description

Back contact batteries, battery strings, battery modules and photovoltaic systems

[0001] Priority information

[0002] This application claims priority and benefits to patent application No. 202421616859.0, filed with the China National Intellectual Property Administration on July 09, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application belongs to the field of solar cell technology, and particularly relates to a back contact cell, a cell string, a cell module and a photovoltaic system. Background Technology

[0004] Solar energy is a sustainable and clean energy source. Solar cells utilize the photovoltaic effect of semiconductor pn junctions to convert solar energy into electrical energy. Currently, back-contact solar cells are cells where both the emitter and base contact electrodes are placed on the back of the cell (the non-light-receiving side). Back-contact cells have two doped layers of opposite conductivity on the back of the cell, separated by trenches or an insulating layer. Summary of the Invention

[0005] This application provides a back-contact battery, a battery string, a battery module, and a photovoltaic system.

[0006] The back contact battery provided in this application includes:

[0007] A silicon substrate having a front side and a back side facing away from each other, wherein a first trench and a protrusion are formed on the back side side along a first direction;

[0008] A first doped layer is stacked on the protrusion. The first doped layer is a P-type doped layer. The first doped layer includes a first sub-doped layer and a second sub-doped layer stacked on the protrusion. The first sub-doped layer is stacked on the protrusion, and the second sub-doped layer is stacked on the side of the first sub-doped layer away from the silicon substrate.

[0009] A first insulating layer is stacked on the second sub-doped layer;

[0010] A second doped layer is stacked within the first trench, and the second doped layer is an N-type doped layer.

[0011] A conductive contact structure having a conductivity type opposite to that of the first doped layer, the conductive contact structure including a protrusion extending along the thickness direction of the silicon substrate, the protrusion being at least partially disposed within the first trench, and only a portion of the first doped layer and only a portion of the second doped layer being electrically connected to the protrusion at least, respectively, the thickness of the protrusion in the thickness direction being greater than the total thickness of the protrusion, the first doped layer, and the first insulating layer.

[0012] The battery string provided in this application includes the back contact battery described above.

[0013] The battery assembly provided in this application includes the battery string described above.

[0014] The photovoltaic system provided in this application includes the battery modules as described in the above embodiments.

[0015] In the back-contact battery, battery string, battery module, and photovoltaic system of this application, electrical energy can be released between the first doped layer and the second doped layer through a conductive contact structure. This conductive contact structure can serve as a heat dissipation point, reducing or even eliminating the impact of hot spots and improving the power generation efficiency and safety of the back-contact battery. Simultaneously, the extended portion has a relatively large thickness along the thickness direction, allowing it to be electrically connected to the first and second sub-doped layers, forming multiple leakage points and further improving safety. Furthermore, the conductive contact structure can have the same conductivity type as the second doped layer and be integrally continuous, simplifying the fabrication process of the back-contact battery. Attached Figure Description

[0016] Figure 1 is a cross-sectional structural diagram of the back contact battery provided in an embodiment of this application;

[0017] Figure 2 is another cross-sectional structural diagram of the back contact battery provided in an embodiment of this application;

[0018] Figure 3 is another cross-sectional structural diagram of the back contact battery provided in the embodiment of this application;

[0019] Figure 4 is another cross-sectional structural schematic diagram of the back contact battery provided in the embodiment of this application;

[0020] Figure 5 is another cross-sectional structural schematic diagram of the back contact battery provided in the embodiment of this application;

[0021] Figure 6 is another cross-sectional structural schematic diagram of the back contact battery provided in the embodiment of this application;

[0022] Figure 7 is another cross-sectional structural schematic diagram of the back contact battery provided in the embodiment of this application;

[0023] Figure 8 is a schematic diagram of the planar structure of the back contact battery provided in an embodiment of this application;

[0024] Figure 9 is a schematic diagram of the structure of the battery assembly provided in an embodiment of this application;

[0025] Figure 10 is a schematic diagram of the structure of the photovoltaic system provided in the embodiment of this application.

[0026] Explanation of key component symbols:

[0027] The components include: a back contact cell 100, a silicon substrate 10, a front side 11, a back side 12, a first trench 121, a protrusion 122, a second trench 123, a first doped layer 20, a first sub-doped layer 21, a second sub-doped layer 22, a first inner expansion layer 23, a first barrier layer 24, a protruding portion 25, a retracted region 26, a second doped layer 30, a second inner expansion layer 31, a third sub-doped layer 32, a fourth sub-doped layer 33, a second barrier layer 34, a first insulating layer 40, a conductive contact structure 50, a protruding portion 51, a first side 511, a second side 512, a covering portion 52, an insulating dielectric layer 60, a second insulating layer 70, a first insulating portion 71, a second insulating portion 72, a third insulating portion 73, a first dielectric layer 81, a second dielectric layer 82, a third dielectric layer 83, a main grid 91, a sub-grid 92, a fine grid 93, a cell string 200, a cell module 300, and a photovoltaic system 400. Embodiments of the present invention

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.

[0029] In the description of this application, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0031] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0032] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0033] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0034] In related technologies, back-contact solar cells have two doped layers with opposite conductivity types on the back side of the cell. These two doped layers are completely isolated, resulting in a high reverse breakdown voltage. This leads to a higher risk of hot spots in photovoltaic modules, including those using existing back-contact solar cells, during actual operation. In other words, the safety performance of photovoltaic modules equipped with existing back-contact solar cells needs improvement. In this application, the conductive contact structure can serve as a heat dissipation point, reducing or even eliminating the impact of hot spots and improving the power generation efficiency and safety of the back-contact solar cell. Simultaneously, the extended portion has a larger thickness along the thickness direction, allowing it to electrically connect with the first and second sub-doped layers, forming multiple leakage points and further improving safety. Furthermore, the conductive contact structure can have the same conductivity type as the second doped layer and be integrally continuous, simplifying the fabrication process of the back-contact solar cell.

[0035] Please refer to Figures 1, 2 and 3. The back contact battery 100 provided in this application includes a silicon substrate 10, a first doped layer 20, a first insulating layer 40, a second doped layer 30 and a conductive contact structure 50.

[0036] The silicon substrate 10 has a front side 11 and a back side 12 facing away from each other. A first trench 121 and a protrusion 122 are formed on the back side 12 along a first direction. A first doped layer 20 is stacked on the protrusion 122. The first doped layer 20 includes a first sub-doped layer 21 and a second sub-doped layer 22 stacked on the protrusion 122. The first sub-doped layer 21 is stacked on the protrusion 122, and the second sub-doped layer 22 is stacked on the side of the first sub-doped layer 21 away from the silicon substrate 10.

[0037] A first insulating layer 40 is stacked on the second sub-doped layer 22, and a second doped layer 30 is stacked within the first trench 121. The second doped layer 30 has the opposite polarity to the first doped layer 20. The conductive contact structure 50 has the opposite conductivity type to the first doped layer 20. The conductive contact structure 50 includes a protrusion 51 that extends along the thickness direction of the silicon substrate 10. The protrusion 51 is at least partially disposed within the first trench 121. Only a portion of the first doped layer 20 and only a portion of the second doped layer 30 are electrically connected to the protrusion 51. The thickness of the protrusion 51 in the thickness direction is greater than the total thickness of the protrusion 122, the first doped layer 20, and the first insulating layer 40.

[0038] In this embodiment, the front side 11 of the silicon substrate 10 is used to receive light, and the back side 12 of the silicon substrate 10 is formed with a first doped layer 20 and a second doped layer 30. On the back side 12 of the silicon substrate 10, a first trench 121 and a protrusion 122 are arranged along a first direction, and the first doped layer 20 and the second doped layer 30 respectively disposed in the protrusion 122 and the first trench 121 are also arranged along the first direction to form a photocurrent.

[0039] In addition, in this embodiment, a conductive contact structure 50 is formed between the first doped layer 20 and the second doped layer 30. The conductivity type of the conductive contact structure 50 is opposite to that of the first doped layer 20 and the same as that of the second doped layer 30. The protrusion 51 of the conductive contact structure 50 can extend from the first trench 121. The portion of the protrusion 51 located in the first trench 121 can be electrically connected to the second doped layer 30. At the same time, the protrusion 51 extends upward along the thickness direction, and the thickness of the protrusion 51 in the thickness direction is greater than the total thickness of the protrusion 122, the first doped layer 20, and the first insulating layer 40. In this way, the protrusion 51 can make electrical contact with the first sub-doped layer 21 and the second sub-doped layer 22 respectively. That is to say, the protrusion 51 can form local leakage points at the contact positions with the first sub-doped layer 21 and the second sub-doped layer 22 respectively, so as to electrically connect the first doped layer 20 and the second doped layer 30 to form a built-in diode with a low reverse breakdown voltage, thereby making the back contact battery 100 have a low reverse breakdown voltage when it is blocked, and eliminating the influence of hot spots.

[0040] Referring to Figures 1 and 2, in some alternative embodiments, the first doped layer 20 further includes a first barrier layer 24, which is stacked between the first sub-doped layer 21 and the second sub-doped layer 22.

[0041] Specifically, a first barrier layer 24 may be disposed between the first sub-doped layer 21 and the second sub-doped layer 22. The first barrier layer 24 is stacked on the first sub-doped layer 21, and the second sub-doped layer 22 is stacked on the side of the first barrier layer 24 away from the first sub-doped layer 21. The widths of the first sub-doped layer 21, the first barrier layer 24, and the second sub-doped layer 22 in the first direction can be the same, so that the protrusion 51 can be electrically connected to the first sub-doped layer 21, the first barrier layer 24, and the second sub-doped layer 22 simultaneously. It is understood that the thickness of the protrusion 51 in the thickness direction is greater than the total thickness of the protrusion 122, the first sub-doped layer 21, the first barrier layer 24, the second sub-doped layer 22, and the first insulating layer 40, to ensure that the protrusion 51 can stably form leakage points with the first sub-doped layer 21 and the second sub-doped layer 22 respectively, further improving safety.

[0042] Furthermore, only a portion of the first doped layer 20 and only a portion of the second doped layer 30 are electrically connected to the protrusion 51, meaning that the protrusion 51 can make electrical contact with portions of the first doped layer 20 and the second doped layer 30, respectively. Other areas of the first doped layer 20 and the second doped layer 30 can be physically isolated through the design of the first trench 121 and the protrusion 122, preventing the first doped layer 20 and the second doped layer 30 from making full contact through the conductive contact structure 50, which would result in a large leakage current in the back contact battery 100 under normal operating conditions, leading to low operating efficiency. Additionally, the first sub-doped layer 21 and the second sub-doped layer 22 can also act as mutual safety devices. If either the first sub-doped layer 21 or the second sub-doped layer 22 is damaged or short-circuited, the other sub-doped layer can form a leakage point with the second doped layer 30 through the protrusion 51, further improving safety.

[0043] In one embodiment, the first trench 121 and the protrusion 122 are alternately arranged along a first direction, and the first trench 121 and the protrusion 122 extend along a second direction. That is, the first doped layer 20 and the second doped layer 30 are also alternately arranged in strips along the first direction and extend along the second direction. The second direction is perpendicular to the first direction and is located in the horizontal direction. That is, the plane formed by the first direction and the second direction is perpendicular to the thickness direction of the silicon substrate 10.

[0044] Referring to Figure 3, in this embodiment, a second trench 123 extending along a second direction can also be formed on the back surface 12. The second trench 123 is disposed between the first trench 121 and the protrusion 122 to physically isolate the first doped layer 20 and the second doped layer 30. In this embodiment, the second trench 123 can be disposed at any position between any adjacent first trench 121 and protrusion 122, and is not specifically limited here. In one example, the second trench 123 can be formed by continuing to excavate into the silicon substrate 10 based on the first trench 121 to form a deeper second trench 123. In another example, the second trench 123 can be formed by continuing to excavate into the silicon substrate 10 based on the protrusion 122 to form a second trench 123 that is deeper than the first trench 121. The specific location and distribution pattern of the trench are not limited here to meet various needs.

[0045] Referring to Figures 2 and 4, in the embodiments of this application, the first doped layer 20 and the second doped layer 30 can be P-type and N-type doped layers, respectively, as long as their polarities are opposite. For example, in some embodiments, the first doped layer 20 can be a P-type polycrystalline silicon layer, a P-type amorphous silicon layer, or a P-type microcrystalline silicon layer, without specific limitations. Similarly, the second doped layer 30 can be an N-type polycrystalline silicon layer, an N-type amorphous silicon layer, or an N-type microcrystalline silicon layer, without specific limitations. When the first doped layer 20 is a P-type doped layer and the second doped layer 30 is an N-type doped layer, a P-type main gate 91 can be provided on the protrusion 122, and an N-type sub-gate 92 can be provided on the first trench 121. Of course, in other embodiments, a P-type fine gate 93 can be provided on the protrusion 122, and an N-type sub-gate 92 can be provided on the first trench 121, without specific limitations.

[0046] Of course, in other embodiments, the first doped layer 20 and the second doped layer 30 can also be N-type doped layer and P-type doped layer, respectively. That is, the first doped layer 20 is an N-type doped layer and the second doped layer 30 is a P-type doped layer. No specific limitation is made here.

[0047] In this embodiment, the width of the protrusion 122 and the first groove 121 in the first direction, as well as the ratio of the protrusion 122 to the first groove 121, are not limited; any requirement can be met. Furthermore, in this embodiment, the height ratio between the protrusion 122 and the first groove 121 is also not limited, in order to meet different requirements.

[0048] Please refer to Figure 5. As shown in Figure 5, in some embodiments, the first doped layer 20 can be a P-type doped layer 101, such as a P-type polycrystalline silicon layer, a P-type amorphous silicon layer, or a P-type microcrystalline silicon layer. The second doped layer 30 can be an N-type doped layer 102, such as an N-type polycrystalline silicon layer, an N-type amorphous silicon layer, or an N-type microcrystalline silicon layer. That is, in such embodiments, both the first sub-doped layer 21 and the second sub-doped layer 22 can be N-type doped layers, and the second doped layer 30 can be a P-type doped layer. For the conductive contact structure 50, the protrusion 51 in the conductive contact structure 50 can have the same doping type as the second doped layer 30, which is P-type doping.

[0049] Thus, by setting the doping type of the first doped layer 20 to P-type doping and setting both the second doped layer 30 and the protrusion 51 to N-type doping, compared to setting the first doped layer 20 to N-type doping and the second doped layer 30 and the protrusion 51 to P-type doping, the second doped layer 30 and the protrusion 51 with N-type doping can improve the passivation effect on the surface of the first trench 121 and the side of the protrusion 122, thereby improving the performance of the back contact battery 100.

[0050] Please refer to Figures 1, 2 and 5. In some optional embodiments, the conductive contact structure 50 further includes a cover portion 52, which is stacked on the first insulating layer 40, and the end of the protrusion 51 away from the first trench 121 is connected to the cover portion 52.

[0051] Thus, the protrusion 51 and the cover 52 can be integrally formed, thereby simplifying the manufacturing difficulty of the conductive contact structure 50. At the same time, the cover 52 can cooperate with the protrusion 51 to wrap around and cover one side of the first doped layer 20 and the first insulating layer 40, avoiding insufficient protrusion distance of the protrusion 51, which would prevent the formation of a leakage point between the protrusion 51 and the first sub-doped layer 21 and the second sub-doped layer 22, thereby improving the manufacturing efficiency of the back contact battery 100.

[0052] Specifically, the protrusion 51 and the cover 52 of the conductive contact structure 50 can be an integral structure to reduce etching precision and difficulty. At the same time, it can also ensure that the protrusion 51 corresponding to the first doped layer 20 can cover the first sub-doped layer 21 and the second sub-doped layer 22, forming a local electrical connection.

[0053] Please refer to Figures 1 and 2. In some alternative embodiments, the conductive contact structure 50 and the second doped layer 30 have the same conductivity type and are integrally continuous.

[0054] Thus, the conductive contact structure 50 and the second doped layer 30 have the same conductivity type and are integrally continuous. In other words, the conductive contact structure 50 and the second doped layer 30 can essentially be the same material layer. This allows the conductive contact structure 50 and the second doped layer 30 to be manufactured simultaneously using the same process, thereby reducing the manufacturing difficulty of the conductive contact structure 50, simplifying the manufacturing process of the conductive contact structure 50, and improving the manufacturing efficiency of the back contact battery 100.

[0055] In addition, in this application, the first doped layer 20 may be a P-type doped layer, the second doped layer 30 may be an N-type doped layer, and the protruding portion 51 and the covering portion 52 of the conductive contact structure 50 may also both be N-type doped layers.

[0056] Please refer to Figures 1 and 2. In some optional embodiments, the back contact battery 100 further includes a first dielectric layer 81, a second dielectric layer 82 and a third dielectric layer 83, wherein the first dielectric layer 81 is located between the first doped layer 20 and the silicon substrate 10.

[0057] The third dielectric layer 83 is located between the second doped layer 30 and the silicon substrate 10;

[0058] The second dielectric layer 82 is at least partially disposed within the first trench 121 and adheres to the sidewall of the protrusion 122.

[0059] In this embodiment, the first dielectric layer 81, the second dielectric layer 82, and the third dielectric layer 83 can be tunneling oxide layers. The tunneling oxide layer plays a tunneling effect, enabling charge carriers to be transported through the thin tunneling oxide layer, while providing a good surface passivation effect, reducing the recombination rate, and thus improving the efficiency of the back contact battery 100.

[0060] In this embodiment, the specific materials of the first dielectric layer 81, the second dielectric layer 82, and the third dielectric layer 83 are not limited to meet different needs. Furthermore, the materials of the first dielectric layer 81, the second dielectric layer 82, and the third dielectric layer 83 can be the same or different. Referring to Figure 1, the first dielectric layer 81, the second dielectric layer 82, and the third dielectric layer 83 are made of the same material; referring to Figure 2, the first dielectric layer 81, the second dielectric layer 82, and the third dielectric layer 83 are made of different materials. When the materials of the first dielectric layer 81, the second dielectric layer 82, and the third dielectric layer 83 are different, the first dielectric layer 81, the second dielectric layer 82, and the third dielectric layer 83 have a discontinuous structure.

[0061] Referring to Figures 1 and 2, in some alternative embodiments, the second dielectric layer 82 extends in a thickness direction away from the silicon substrate 10, and the second dielectric layer 82 is at least partially electrically connected to the first doped layer 20.

[0062] Thus, both the second dielectric layer 82 and the protrusion 51 can be partially disposed in the first trench 121 and extend along the thickness direction of the silicon substrate 10. That is to say, the protrusion 51 can be electrically connected to the first doped layer 20 through the second dielectric layer 82.

[0063] Specifically, the second dielectric layer 82 can cover the entire first sub-doped layer 21 and the first barrier layer 24 on the side and contact a portion of the second sub-doped layer 22, so that the contact surfaces between the protrusion 51 and the second dielectric layer 82 are all effective electrical contact surfaces.

[0064] Referring to Figures 1 and 2, in some alternative embodiments, the back contact battery 100 further includes an insulating dielectric layer 60, which is connected to one end of the second dielectric layer 82 away from the silicon substrate 10. The insulating dielectric layer 60 is at least partially connected to the first doped layer 20 and the first insulating layer 40 on the side near the protrusion 122.

[0065] In this embodiment, the insulating dielectric layer 60 and the second dielectric layer 82 are flush with each other on the side near the protrusion 51, so that the side surface of the protrusion 51 near the protrusion 122 is flat and regular, which helps to reduce the manufacturing difficulty of the conductive contact structure 50 and improve the yield of the back contact battery 100.

[0066] Please refer to Figures 1 and 2. In some alternative embodiments, the width of the insulating dielectric layer 60 in the first direction is greater than the width of the second dielectric layer 82.

[0067] In this way, the insulating dielectric layer 60 can cooperate with the first insulating layer 40 to cover and shield the first doped layer 20. At the same time, the insulating dielectric layer 60 can also extend partially into the protrusion 51 along the first direction, so that the first doped layer 20 can be electrically connected to the protrusion 51, while avoiding contact with the covering part 52, thereby improving the stability of the conductive contact structure 50.

[0068] Please refer to Figures 1 and 2. In some alternative embodiments, the protrusion 51 further includes a first side 511 and a second side 512 disposed along the thickness direction. The first side 511 is the side close to the protrusion 122 and contacts the second dielectric layer 82. The second side 512 is the side close to the first trench 121.

[0069] In this embodiment, the insulating dielectric layer 60 protrudes from the first side 511 near the first trench 121. The top of the first side 511 is the insulating dielectric layer 60, and the bottom of the first side 511 extends into the first trench 121. The first side 511 is attached to the surface of the second dielectric layer 82, and the first doped layer 20 forms a leakage point at the location of the first side 511 through the second dielectric layer 82.

[0070] Referring to Figures 1 and 2, in some optional embodiments, the back contact battery 100 further includes a second insulating layer 70. The second insulating layer 70 includes a first insulating portion 71, a second insulating portion 72, and a third insulating portion 73 connected together in sequence. The first insulating portion 71 is stacked on the cover portion 52, the second insulating portion 72 is disposed on the side of the second side 512 near the first trench 121, and the third insulating portion 73 is stacked on the second doped layer 30.

[0071] Thus, the second insulating layer 70 can protect the covering portion 52, the protruding portion 51, and the second doped layer 30 in sequence through the first insulating portion 71, the second insulating portion 72, and the third insulating portion 73, thereby preventing the conductive contact structure 50 and the second doped layer 30 from being exposed.

[0072] In this embodiment, the second insulating layer 70 can be a passivation film. When the first doped layer 20 is a P-type doped layer and the second doped layer 30 is an N-type doped layer, the surface roughness of the second doped layer 30 in contact with the first insulating portion 71 is greater than the surface roughness of the first doped layer 20 in contact with the first insulating portion 71. This makes the bonding pull between the first insulating portion 71 and the second doped layer 30 greater than the bonding pull between the first insulating portion 71 and the first doped layer 20, thereby effectively preventing the solder joint from detaching during welding and improving the reliability of welding.

[0073] In some embodiments, the passivation film may include at least one of silicon nitride film, aluminum oxide film, silicon oxynitride film, intrinsic amorphous silicon film, and TCO film, without being specifically limited herein.

[0074] Referring to Figures 1 and 2, in some alternative embodiments, the first doped layer 20 further includes a protrusion 25 extending in a first direction above the first trench 121, and the second dielectric layer 82 surrounds the protrusion 25.

[0075] In this way, the first doped layer 20 can form a larger contact area through the protrusion 25 and the extension 51, thereby improving the conductivity and quickly eliminating the influence of hot spots.

[0076] In this embodiment, the shape of the protrusion 25 is not limited to meet different needs. For example, the end of the protrusion 25 near the first trench 121 intersects to form a sharp point, and the closer it is to the first trench 121, the sharper the end of the protrusion 25 becomes. Alternatively, the end of the protrusion 25 near the first trench 121 can be rectangular. In this case, the width of the second dielectric layer 82 along the thickness direction of the silicon substrate 10 is smaller than the width of the second dielectric layer 82 along the first direction, making the first sub-doped layer 21 closer to the protrusion 51 in the thickness direction. The first sub-doped layer 21 can form a leakage point at this location, further improving safety.

[0077] Referring to Figure 2, in some embodiments, the second dielectric layer 82 includes a first region 821 and a second region 822 connected together. The first region 821 extends along a first direction, and the second region 822 extends along the thickness direction. The top of the second region 822 is an insulating dielectric layer 60, and the two sides of the second region 822 are a second doped layer 30 and a first side 511, respectively. The bottom of the second region 822 is connected to the first region 821. The top of the first region 821 is at least partially in contact with the first sub-doped layer 21, and the bottom of the first region 821 is at least partially in contact with the protrusion 51. That is to say, a leakage point can also be formed at the location of the first region 821 to eliminate hot spots.

[0078] Specifically, the side surface of the protruding portion 25 along the first direction is the second region 822, and the bottom surface of the protruding portion 25 along the thickness direction is the first region 821. The first region 821 and the second region 822 are provided with a portion of the second dielectric layer 82. In other words, a part of the second dielectric layer 82 can be provided in the first region 821, and another part of the second dielectric layer 82 can be provided in the second region 822.

[0079] In some embodiments, the thickness of the first region 821 in the thickness direction is thinner than the width of the second region 822 in the first direction. That is, the distance between the first doped layer 20 and the protrusion 51 is closer in the first region 821, which makes the leakage point formed through the first region 821 more conductive and safer.

[0080] Referring to Figure 6, in some embodiments, the first doped layer 20 further includes a retracted region 26 that extends along a first direction above the protrusion 122, and the second dielectric layer 82 is correspondingly disposed in the retracted region 26. In this way, the first doped layer 20 can form a larger contact area with the protrusion 51 through the retracted region 26, thereby improving conductivity and quickly eliminating the influence of hot spots.

[0081] Please refer to Figures 1 and 2. In some alternative embodiments, the thickness of the first sub-doped layer 21 in the thickness direction is greater than the thickness of the second sub-doped layer 22.

[0082] Thus, the first sub-doped layer 21, which is closer to the silicon substrate 10, is thicker than the second sub-doped layer 22, making the silicon substrate 10 more stable, with better passivation, better refractive index, and higher light reception efficiency.

[0083] In other embodiments, the first doped layer 20 may further include multiple other sub-doped layers, all of which are stacked, and a first barrier layer 24 is formed between each sub-doped layer. In this embodiment, the number of sub-doped layers is not limited; it is only necessary to ensure that the sub-doped layers closer to the silicon substrate 10 are thicker to meet different requirements.

[0084] Please refer to Figures 1 and 2. In some optional embodiments, the thickness of the first sub-doped layer 21 in the thickness direction is 50nm-300nm; the thickness of the second sub-doped layer 22 in the thickness direction is 30nm-200nm.

[0085] For example, the thickness of the first sub-doped layer 21 in the thickness direction can be 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm, 210nm, 220nm, 230nm, 240nm, 250nm, 260nm, 270nm, 280nm, 290nm, or 300nm. The thickness of the second sub-doped layer 22 in the thickness direction can be 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, or 200nm. The thicknesses of the first sub-doped layer 21 and the second sub-doped layer 22 are set within this range in the thickness direction, which ensures the basic function of the first doped layer 20 while reducing the difficulty of fabrication.

[0086] In the embodiments of this application, the thickness of the first sub-doped layer 21 and the second sub-doped layer 22 is not specifically limited, as long as the thickness of the first sub-doped layer 21 in the thickness direction is greater than the thickness of the second sub-doped layer 22.

[0087] In one example, the thickness of the first sub-doped layer 21 in the thickness direction can be 200 nm, while the thickness of the second sub-doped layer 22 in the thickness direction can be 100 nm. In this way, the first doped layer 20 can be kept within a suitable thickness range, and in conjunction with the protrusion 51, the number of leakage points can be increased while maintaining a thin and light profile, thereby improving the safety of the back contact battery 100.

[0088] Referring to Figures 1 and 2, in some alternative embodiments, the first doped layer 20 further includes a first inner expansion layer 23 formed in the protrusion 122, and the second doped layer 30 further includes a second inner expansion layer 31 formed in the first trench 121.

[0089] Thus, the first doped layer 20 can form a first inner expansion layer 23 on the side of the first dielectric layer 81 close to the silicon substrate 10 through a diffusion process, and the second doped layer 30 can form a second inner expansion layer 31 on the side of the third dielectric layer 83 close to the silicon substrate 10 through a diffusion process. The combination of the inner expansion layer with the tunneling oxide layer and the polycrystalline silicon layer further improves the efficiency and stability of the battery.

[0090] In this embodiment, the thickness of the protrusion 51 in the thickness direction of the silicon substrate 10 is greater than the total thickness of the protrusion 122, the first inner expansion layer 23, the first doped layer 20, and the first insulating layer 40. That is, the side of the first inner expansion layer 23 near the first trench 121 is in contact with the second dielectric layer 82, and the second dielectric layer 82 is electrically connected to the protrusion 51. The first inner expansion layer 23 and the protrusion 51 can form a new leakage point. Electrical energy can be released between the first inner expansion layer 23 and the second doped layer 30 through the protrusion 51 to reduce or even eliminate the influence of hot spots, and further improve the power generation efficiency and safety of the back contact battery 100.

[0091] Referring to Figure 7, in some alternative embodiments, the second doped layer 30 includes a third sub-doped layer 32 and a fourth sub-doped layer 33 stacked together. The third sub-doped layer 32 is stacked on the first trench 121, and the fourth sub-doped layer 33 is stacked on the side of the third sub-doped layer 32 away from the silicon substrate 10.

[0092] In some alternative embodiments, the second doped layer 30 further includes a second barrier layer 34, which is stacked between the third sub-doped layer 32 and the fourth sub-doped layer 33.

[0093] Specifically, a second barrier layer 34 may be disposed between the third sub-doped layer 32 and the fourth sub-doped layer 33. The second barrier layer 34 is stacked on the third sub-doped layer 32, and the fourth sub-doped layer 33 is stacked on the side of the second barrier layer 34 away from the third sub-doped layer 32. The widths of the third sub-doped layer 32, the second barrier layer 34, and the fourth sub-doped layer 33 in the first direction may be the same, so that the protruding portion 51 can be electrically connected to the third sub-doped layer 32, the second barrier layer 34, and the fourth sub-doped layer 33 simultaneously.

[0094] Furthermore, the first barrier layer 24 and the second barrier layer 34 act as barriers, forming a doping concentration difference between the two sub-layer doped layers. This can further improve the passivation effect of the passivation contact structure of the back contact battery 100 and improve the efficiency of the back contact battery 100. In this embodiment, the range of doping concentration of the doped layers on both sides of the first barrier layer 24 and the second barrier layer 34 is not limited to meet different needs.

[0095] Furthermore, when the conductive contact structure 50 and the second doped layer 30 have the same conductivity type and are integrally continuous, the second barrier layer 34 can extend from the second doped layer 30 along the protrusion 51 and the cover portion 52, so that the protrusion 51 and the cover portion 52 are also divided into two doped layers. In this way, the conductive contact structure 50 and the second doped layer 30 can be fabricated together during the fabrication process, saving fabrication steps and improving production efficiency.

[0096] Furthermore, the thickness of the first barrier layer 24 is less than the thickness of the first dielectric layer 81 in the thickness direction. Thus, voids are provided in the first barrier layer 24, thereby adjusting the doping concentration of the first sub-doped layer 21 and the second sub-doped layer 22.

[0097] Please refer to Figures 8 and 9. The battery string 200 provided in this application includes a back contact battery 100 as described in any of the above embodiments.

[0098] In the back contact battery 100 and battery string 200 of the embodiments of this application, the back contact battery 100 includes a silicon substrate 10, a first doped layer 20, a first insulating layer 40, a second doped layer 30, and a conductive contact structure 50. The silicon substrate 10 has a front side 11 and a back side 12 facing away from each other. A first trench 121 and a protrusion 122 are formed on the back side 12 along a first direction. The first doped layer 20 is stacked on the protrusion 122. The first doped layer 20 includes a first sub-doped layer 21 and a second sub-doped layer 22 stacked on it. The first sub-doped layer 21 is stacked on the protrusion 122, and the second sub-doped layer 22 is stacked on the side of the first sub-doped layer 21 away from the silicon substrate 10. An insulating layer 40 is stacked on the second sub-doped layer 22, and a second doped layer 30 is stacked within the first trench 121. The second doped layer 30 has the opposite polarity to the first doped layer 20. The conductivity type of the conductive contact structure 50 is opposite to that of the first doped layer 20. The conductive contact structure 50 includes a protrusion 51 that extends along the thickness direction of the silicon substrate 10. The protrusion 51 is at least partially disposed within the first trench 121. Only a portion of the first doped layer 20 and only a portion of the second doped layer 30 are electrically connected to the protrusion 51. The thickness of the protrusion 51 in the thickness direction is greater than the total thickness of the protrusion 122, the first doped layer 20, and the first insulating layer 40. Thus, electrical energy can be released between the first doped layer 20 and the second doped layer 30 through the conductive contact structure 50. The conductive contact structure 50 can serve as a heat dissipation point, reducing or even eliminating the impact of hot spots and improving the power generation efficiency and safety of the back contact battery 100. Meanwhile, the protrusion 51 has a relatively large thickness along the thickness direction, allowing it to be electrically connected to the first sub-doped layer 21 and the second sub-doped layer 22, forming multiple leakage points and further improving safety. Additionally, the conductive contact structure 50 can be integrally continuous with the second doped layer 30 and have the same conductivity type, simplifying the fabrication process of the back contact battery 100.

[0099] Specifically, the first doped layer 20 and the second doped layer 30 have opposite polarities. The first doped layer 20 and the second doped layer 30 are P-type doped and N-type doped, respectively. In some embodiments, P-type doping refers to doping with group III elements, including boron, aluminum, gallium, indium, thallium, etc.; N-type doping refers to doping with group V elements, including nitrogen, phosphorus, arsenic, antimony, bismuth, etc., and the specific doping is not limited here.

[0100] In some embodiments, the first doped layer 20 and the second doped layer 30 can also be composite doped, for example, N-type doping also includes a small amount of P-type doping elements. Specifically, the content of N-type doping elements in the second doped layer 30 is higher than 20% of the content of P-type doping elements, to ensure that the polarity is opposite to that of the first doped layer 20.

[0101] Furthermore, the conductive contact structure 50 has the same conductivity type as the second doped layer 30, but the opposite conductivity type to the first doped layer 20. Since the conductive contact structure 50 is not a doped region, its conductivity type is N-type doping, and the dominant charge carrier is electrons. In other words, electrons are the majority carrier in N-type doping, while holes are the majority carrier in P-type doping. The conductive contact structure 50 has the same conductivity type as the N-type doped region, but a different conductivity type than the P-type doped region.

[0102] For example, in some embodiments, the first doped layer 20 may be a P-type polycrystalline silicon layer, a P-type amorphous silicon layer, or a P-type microcrystalline silicon layer, and there is no specific limitation herein. Similarly, the second doped layer 30 and the conductive contact structure 50 may be an N-type polycrystalline silicon layer, an N-type amorphous silicon layer, or an N-type microcrystalline silicon layer, and there is no specific limitation herein.

[0103] In this embodiment, the battery string 200 can be a series connection of multiple sheet-like back contact batteries 100 connected by solder strips and busbars. It is understood that the battery string 200 can include two, three, or more battery cells connected in series, depending on the specific application. Furthermore, in this embodiment, the size and type of the back contact batteries 100 are not limited; adjacent battery cells can have the same or different specifications and dimensions to meet different needs.

[0104] In this application, the specific connection method of adjacent solar cells is not limited to meet different needs. In one embodiment, the edges of two adjacent solar cells are at least partially stacked together; in another embodiment, two adjacent solar cells can be spaced apart. A suitable spacing between two adjacent solar cells can avoid the problems of insufficient operating space and difficult welding caused by too small a spacing, and can also avoid the problems of wasted component space and increased costs caused by too large a spacing.

[0105] Please refer to Figures 8 and 9. The battery assembly 300 provided in this application embodiment includes the battery string 200 as described in the above embodiment.

[0106] In the back contact battery 100, battery string 200, and battery assembly 300 of the embodiments of this application, the back contact battery 100 includes a silicon substrate 10, a first doped layer 20, a first insulating layer 40, a second doped layer 30, and a conductive contact structure 50. The silicon substrate 10 has a front side 11 and a back side 12 facing away from each other. A first trench 121 and a protrusion 122 are formed on the back side 12 along a first direction. The first doped layer 20 is stacked on the protrusion 122. The first doped layer 20 includes a first sub-doped layer 21 and a second sub-doped layer 22 stacked on it. The first sub-doped layer 21 is stacked on the protrusion 122, and the second sub-doped layer 22 is stacked on the first sub-doped layer 21 away from the silicon substrate 10. On the first trench 121, a first insulating layer 40 is stacked on the second sub-doped layer 22, and a second doped layer 30 is stacked within the first trench 121. The second doped layer 30 has the opposite polarity to the first doped layer 20. The conductive contact structure 50 has the opposite conductivity type to the first doped layer 20. The conductive contact structure 50 includes a protrusion 51 that extends along the thickness direction of the silicon substrate 10. The protrusion 51 is at least partially disposed within the first trench 121. Only a portion of the first doped layer 20 and only a portion of the second doped layer 30 are electrically connected to the protrusion 51. The thickness of the protrusion 51 in the thickness direction is greater than the total thickness of the protrusion 122, the first doped layer 20, and the first insulating layer 40. Thus, electrical energy can be released between the first doped layer 20 and the second doped layer 30 through the conductive contact structure 50. The conductive contact structure 50 can serve as a heat dissipation point, reducing or even eliminating the impact of hot spots and improving the power generation efficiency and safety of the back contact battery 100. Meanwhile, the protrusion 51 has a relatively large thickness along the thickness direction, allowing it to be electrically connected to the first sub-doped layer 21 and the second sub-doped layer 22, forming multiple leakage points and further improving safety. Additionally, the conductive contact structure 50 can be integrally continuous with the second doped layer 30 and have the same conductivity type, simplifying the fabrication process of the back contact battery 100.

[0107] In this embodiment, multiple back-contact batteries 100 in the battery assembly 300 can be connected in series to form a battery string 200, thereby realizing the series current charging output. For example, the battery cells can be connected in series by setting solder strips (busbars, interconnecting strips), conductive backplates, etc.

[0108] It is understood that in such an embodiment, the battery assembly 300 may further include a frame, a backsheet, photovoltaic glass, and an encapsulating film. The encapsulating film may be filled between the front and back sides 11 and 12 of the back-contact battery 100, the photovoltaic glass, adjacent battery cells, etc. As a filler, it may be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulating film may be an EVA film or a POE film, and the specific choice can be made according to the actual situation, without limitation.

[0109] Photovoltaic glass can be applied to the encapsulant film on the front side 11 of the back contact cell 100. The photovoltaic glass can be ultra-clear glass, which has high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, ultra-clear glass can have a light transmittance of over 92%, protecting the back contact cell 100 while minimizing impact on its efficiency. Simultaneously, the encapsulant film bonds the photovoltaic glass and the back contact cell 100 together, providing sealing, insulation, waterproofing, and moisture protection for the back contact cell 100.

[0110] The backsheet can be attached to the adhesive film on the back side 12 of the back contact cell 100. The backsheet provides protection and support for the back contact cell 100, and has reliable insulation, water resistance, and aging resistance. Multiple options are available for the backsheet, typically tempered glass, acrylic glass, aluminum alloy TPT composite adhesive film, etc., and the specific choice depends on the specific circumstances and is not limited here. The backsheet, back contact cell 100, adhesive film, and photovoltaic glass can be integrated into a frame. The frame serves as the main external support structure for the entire battery module 300, providing stable support and installation for the battery module 300. For example, the battery module 300 can be installed at the desired location via the frame.

[0111] Please refer to Figures 9 and 10. The photovoltaic system 400 provided in this application includes the battery module 300 as described in the above embodiments.

[0112] In the back contact cell 100, cell string 200, cell module 300, and photovoltaic system 400 of the embodiments of this application, the back contact cell 100 includes a silicon substrate 10, a first doped layer 20, a first insulating layer 40, a second doped layer 30, and a conductive contact structure 50. The silicon substrate 10 has a front side 11 and a back side 12 facing away from each other. A first trench 121 and a protrusion 122 are formed on the back side 12 along a first direction. The first doped layer 20 is stacked on the protrusion 122. The first doped layer 20 includes a first sub-doped layer 21 and a second sub-doped layer 22 stacked on the protrusion 122. The first sub-doped layer 21 is stacked on the protrusion 122, and the second sub-doped layer 22 is stacked on the first sub-doped layer 21 away from the silicon substrate. On one side of the silicon substrate 10, a first insulating layer 40 is stacked on the second sub-doped layer 22, and a second doped layer 30 is stacked in the first trench 121. The second doped layer 30 has the opposite polarity to the first doped layer 20. The conductivity type of the conductive contact structure 50 is opposite to that of the first doped layer 20. The conductive contact structure 50 includes a protrusion 51 that extends along the thickness direction of the silicon substrate 10. The protrusion 51 is at least partially disposed in the first trench 121. Only a portion of the first doped layer 20 and only a portion of the second doped layer 30 are electrically connected to the protrusion 51 at least. The thickness of the protrusion 51 in the thickness direction is greater than the total thickness of the protrusion 122, the first doped layer 20, and the first insulating layer 40.

[0113] Thus, electrical energy can be released between the first doped layer 20 and the second doped layer 30 through the conductive contact structure 50. The conductive contact structure 50 can serve as a heat dissipation point, reducing or even eliminating the impact of hot spots and improving the power generation efficiency and safety of the back contact battery 100. Simultaneously, the protrusion 51 has a relatively large thickness along its thickness direction, allowing it to be electrically connected to the first sub-doped layer 21 and the second sub-doped layer 22, forming multiple leakage points and further improving safety. Furthermore, the conductive contact structure 50 can be of the same conductivity type as the second doped layer 30 and be integrally continuous, simplifying the fabrication process of the back contact battery 100.

[0114] In this embodiment, the photovoltaic system 400 can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It can also be applied to equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the photovoltaic system 400 are not limited to these; that is, the photovoltaic system 400 can be applied in all fields that require solar energy for power generation. Taking a photovoltaic power generation system grid as an example, the photovoltaic system 400 may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules 300. For example, multiple battery modules 300 can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0115] In the description of this specification, the references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0116] Furthermore, the above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A back-contact battery, characterized in that, include: A silicon substrate having a front side and a back side facing away from each other, wherein a first trench and a protrusion are formed on the back side side along a first direction; A first doped layer is stacked on the protrusion. The first doped layer is a P-type doped layer. The first doped layer includes a first sub-doped layer and a second sub-doped layer stacked on the protrusion. The first sub-doped layer is stacked on the protrusion, and the second sub-doped layer is stacked on the side of the first sub-doped layer away from the silicon substrate. A first insulating layer is stacked on the second sub-doped layer; A second doped layer is stacked within the first trench, and the second doped layer is an N-type doped layer. A conductive contact structure having a conductivity type opposite to that of the first doped layer, the conductive contact structure including a protrusion extending along the thickness direction of the silicon substrate, the protrusion being at least partially disposed within the first trench, and only a portion of the first doped layer and only a portion of the second doped layer being electrically connected to the protrusion at least, respectively, the thickness of the protrusion in the thickness direction being greater than the total thickness of the protrusion, the first doped layer, and the first insulating layer.

2. The back contact battery according to claim 1, characterized in that, The conductive contact structure further includes a cover portion, which is stacked on the first insulating layer, and the end of the protrusion portion away from the first trench is connected to the cover portion.

3. The back contact battery according to claim 2, characterized in that, The conductive contact structure has the same conductivity type as the second doped layer and is integrally continuous.

4. The back contact battery according to claim 2, characterized in that, The back contact battery further includes a first dielectric layer, a second dielectric layer and a third dielectric layer, wherein the first dielectric layer is located between the first doped layer and the silicon substrate; The third dielectric layer is located between the second doped layer and the silicon substrate; The second dielectric layer is at least partially disposed within the first trench and adheres to the sidewall of the protrusion.

5. The back contact battery according to claim 4, characterized in that, The second dielectric layer extends in a thickness direction away from the silicon substrate, and the second dielectric layer is at least partially electrically connected to the first doped layer.

6. The back contact battery according to claim 5, characterized in that, The back contact battery further includes an insulating dielectric layer connected to the end of the second dielectric layer away from the silicon substrate. The insulating dielectric layer is at least partially connected to the first doped layer and the first insulating layer on the side near the protrusion.

7. The back contact battery according to claim 6, characterized in that, The width of the insulating dielectric layer in the first direction is greater than the width of the second dielectric layer.

8. The back contact battery according to claim 7, characterized in that, The protrusion further includes a first side and a second side disposed along the thickness direction, the first side being the side closest to the protrusion and contacting the second dielectric layer, and the second side being the side closest to the first trench.

9. The back contact battery according to claim 8, characterized in that, The back contact battery further includes a second insulating layer, which includes a first insulating portion, a second insulating portion and a third insulating portion connected together in sequence. The first insulating portion is stacked on the cover portion, the second insulating portion is disposed on the second side near the first trench, and the third insulating portion is stacked on the second doped layer.

10. The back contact battery according to claim 6, characterized in that, The first doped layer further includes a protrusion extending along the first direction above the first trench, and the second dielectric layer surrounds the protrusion.

11. The back contact battery according to claim 1, characterized in that, The thickness of the first sub-doped layer in the thickness direction is greater than the thickness of the second sub-doped layer.

12. The back contact battery according to claim 11, characterized in that, The thickness of the first sub-doped layer in the thickness direction is 50nm-300nm; The thickness of the second sub-doped layer in the thickness direction is 30nm-200nm.

13. The back contact battery according to claim 1, characterized in that, The first doped layer further includes a first inner expansion layer formed within the protrusion, and the second doped layer further includes a second inner expansion layer formed within the first trench.

14. The back contact battery according to claim 1, characterized in that, The first doped layer further includes a first barrier layer, which is stacked between the first sub-doped layer and the second sub-doped layer.

15. The back contact battery according to claim 14, characterized in that, The thickness of the first barrier layer is less than the thickness of the first dielectric layer in the thickness direction. The first barrier layer has voids to adjust the doping concentration of the first sub-doped layer and the second sub-doped layer.

16. The back contact battery according to claim 1, characterized in that, The second doped layer includes a third sub-doped layer and a fourth sub-doped layer stacked together. The third sub-doped layer is stacked on the first trench, and the fourth sub-doped layer is stacked on the side of the third sub-doped layer away from the silicon substrate.

17. The back contact battery according to claim 16, characterized in that, The second doped layer further includes a second barrier layer, which is stacked between the third sub-doped layer and the fourth sub-doped layer.

18. A battery string, characterized in that, Includes the back contact battery as described in any one of claims 1-17.

19. A battery assembly, characterized in that, Includes the battery string as described in claim 18.

20. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 19.

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