A solar cell, a battery module and a photovoltaic system

Abstract

The present invention discloses a solar cell, a battery assembly and a photovoltaic system. The solar cell includes: a substrate; a first doping layer and a second doping layer alternately arranged on a first surface, with an isolation region separating the adjacent first doping layer and second doping layer; the conductivity type of the first doping layer is different from that of the substrate; the first doping layer includes a first doping portion; both sidewalls of the isolation region are inclined sidewalls, and a first partial region of the inclined sidewalls is provided with a light trapping structure, the light trapping structure including a plurality of stacked zigzag structures; the first doping layer further includes: a second doping portion; the solar cell further includes an extension portion extending from the first doping layer towards the isolation region; the extension portion includes the second doping portion; the tooth top of the zigzag structure on the inclined sidewall close to the first doping layer is in contact with the extension portion. The present invention effectively improves the light utilization rate of the solar cell.

Description

Technical Field

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

[0002] A back contact solar cell is a cell in which both the emitter and base contact electrodes are placed on the back (non-light-receiving surface) of the cell. There is no metal electrode shielding on the light-receiving surface of the cell, thereby effectively increasing the effective light-illuminated area of the cell.

[0003] However, the current BC solar cell has a low light utilization rate. How to effectively increase the light utilization rate of the BC solar cell is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0004] The present invention provides a solar cell, a battery module and a photovoltaic system to solve the problem of low light utilization rate of BC solar cells.

[0005] In a first aspect, the present invention provides a solar cell, wherein the solar cell includes:

[0006] A substrate, the substrate including a first surface and a second surface arranged opposite to each other;

[0007] A first doping layer and a second doping layer alternately arranged on the first surface, the first doping layer and the adjacent second doping layer being separated by an isolation region, the conduction type of the first doping layer being different from that of the second doping layer; the conduction type of the first doping layer being different from that of the substrate;

[0008] The first doping layer includes a first doping portion, the first doping portion being located on the first surface;

[0009] Both side walls of the isolation region are inclined side walls, and a first partial region of the inclined side walls is provided with a light-trapping structure, the light-trapping structure including a plurality of zigzag structures;

[0010] The first doping layer further includes: a second doping portion;

[0011] The solar cell further includes an extension portion extending from the first doping layer towards the isolation region; a vertical projection of the extension portion on the first surface covers a part of a vertical projection of the inclined side wall on the first surface;

[0012] The extension portion includes a second doping portion; the tooth top of the zigzag structure on the inclined side wall close to the first doping layer is in contact with the extension portion.

[0013] Optionally, the first light-trapping structure includes a plurality of stacked zigzag structures.

[0014] Optionally, the tooth tip of the zigzag structure includes a first side surface and a second side surface, and the included angle between the first side surface and the second side surface is greater than or equal to 70° and less than or equal to 110°.

[0015] Optionally, there is a spacing between the tooth tips of two adjacent zigzag structures.

[0016] Optionally, the spacing between the tooth tips of two adjacent zigzag structures is 0.1 um - 3 um.

[0017] Optionally, along the extending direction of the extending portion, the tooth tips of multiple zigzag structures are distributed between the starting position and the ending position of the extending portion.

[0018] Optionally, along the extending direction of the extending portion, there is a spacing between the starting position of the extending portion and the tooth tip of the zigzag structure.

[0019] Optionally, the second doping portion and the first doping portion are integrally provided.

[0020] Optionally, the second doping portion and the first doping portion are provided at intervals.

[0021] Optionally, holes are provided in the portion where the second doping portion and the first doping portion are connected.

[0022] Optionally, the solar cell further includes a passivation layer that wraps the second doping portion, and the extending portion includes the second doping portion and the passivation layer.

[0023] Optionally, the portion of the substrate near the first surface extends to the isolation region in the direction pointing from the first doping layer to the isolation region to form a reflection portion;

[0024] The solar cell further includes a passivation layer that wraps the reflection portion and the second doping portion;

[0025] The extending portion includes the second doping portion, the reflection portion and the passivation layer.

[0026] Optionally, the solar cell further includes a first tunneling layer located between the reflection portion and the second doping portion;

[0027] The extending portion includes the second doping portion, the first tunneling layer, the reflection portion and the passivation layer.

[0028] Optionally, the tooth tip of the zigzag structure on the inclined sidewall near the first doping layer is in contact with the passivation layer;

[0029] Alternatively, the tooth tip of the zigzag structure on the inclined sidewall near the first doping layer is in contact with the passivation layer and the second doping portion;

[0030] Alternatively, the tooth tip of the zigzag structure on the inclined sidewall near the first doping layer is in contact with the passivation layer, the first tunneling layer, and the second doping portion;

[0031] Alternatively, the tooth tops of the zigzag structures on the inclined sidewalls close to the first doping layer are in contact with the passivation layer and the first tunneling layer.

[0032] Optionally, the zigzag structure includes a plurality of protruding portions with different protruding heights in the direction from the first surface to the second surface; the protruding portion in contact with the extending portion is the tooth top of the zigzag structure;

[0033] The adjacent protruding portions are stacked.

[0034] Optionally, the reflecting portion is located on the second partial area of the inclined sidewall close to the connected part of the first doping portion and the second doping portion;

[0035] The vertical projection of the reflecting portion on the first surface is located within the vertical projection of the second doping portion on the first surface.

[0036] Optionally, the included angle between the side of the reflecting portion close to the isolation region and the inclined sidewall ranges from 90° to 120°.

[0037] Optionally, the included angle between the inclined sidewall close to the first doping layer and the side of the first doping portion close to the substrate is an obtuse angle.

[0038] Optionally, the isolation region is provided with an isolation groove, and the isolation groove includes a connected first sub-groove and a second sub-groove;

[0039] The first sub-groove extends from the surface of the first doping layer far from the substrate to the first surface;

[0040] The second sub-groove extends from the first surface into the substrate;

[0041] The inclined sidewall is the sidewall of the second sub-groove.

[0042] In a second aspect, the present invention provides a battery assembly, wherein the battery assembly includes the solar cell provided in the first aspect above.

[0043] In a third aspect, the present invention provides a photovoltaic system, wherein the photovoltaic system includes the battery assembly provided in the second aspect above.

[0044] In the technical solution of the embodiment of the present invention, the two side walls of the isolation region are inclined side walls, and a light-trapping structure composed of a plurality of serrated structures is arranged in a first partial region of the first inclined side wall. The two side walls of the isolation region are the first surface of the substrate, that is, the light-trapping structure can increase the surface area of the first inclined side wall in the first surface, increase the contact area between the first surface and the light irradiated onto the first surface, and enable the first inclined side wall of the first surface to have a high light-trapping effect. When the incident light irradiates the first inclined side wall of the isolation region, the light-trapping structure can effectively increase light trapping and reduce the reflection of the incident light, thereby improving the light absorption of the solar cell and the utilization rate of light by the solar cell, and increasing the current density of the solar cell. The technical solution of the embodiment of the present invention effectively improves the current and carrier transport efficiency of the battery, and finally obtains a solar cell with high conversion efficiency. At the same time, by providing the second doping portion, the reflection of the incident light can be effectively increased, so that the incident light is reflected to the light-trapping structure composed of a plurality of serrated structures, thereby further improving the light absorption of the solar cell and the utilization rate of light by the solar cell, and increasing the current density of the solar cell. Moreover, the tooth crest of the serrated structure on the first inclined side wall close to the first doping layer contacts the extension portion, and the serrated structure can support the extension portion to prevent the second doping portion from falling off, thereby avoiding the short-circuit problem of the solar cell.

[0045] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0047] Figure 1 is a schematic structural diagram of a back-contact solar cell provided by the related art;

[0048] Figure 2 is a schematic structural diagram of a solar cell provided by an embodiment of the present invention;

[0049] Figure 3 is a scanning electron microscope (SEM) image of the inclined side wall of the isolation region provided by an embodiment of the present invention;

[0050] Figure 4 is a schematic structural diagram of another solar cell provided by an embodiment of the present invention;

[0051] Figure 5 It is a top view of a first doping layer provided by an embodiment of the present invention;

[0052] Figure 6 It is a schematic structural diagram of another solar cell provided by an embodiment of the present invention;

[0053] Figure 7 It is a schematic structural diagram of another solar cell provided by an embodiment of the present invention;

[0054] Figure 8 It is a schematic structural diagram of another solar cell provided by an embodiment of the present invention;

[0055] Figure 9 It is a schematic structural diagram of another solar cell provided by an embodiment of the present invention;

[0056] Figure 10 It is a schematic structural diagram of another solar cell provided by an embodiment of the present invention;

[0057] Figure 11 It is a schematic structural diagram of another solar cell provided by an embodiment of the present invention;

[0058] Figure 12 It is a magnification of Figure 3 the AA region in;

[0059] Figure 13 It is a magnification of Figure 12 the BB region in;

[0060] Figure 14 It is a schematic structural diagram of another solar cell provided by an embodiment of the present invention. Detailed implementation manners

[0061] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0062] It should be noted that the terms "first", "second", etc. in the description, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0063] Figure 1 is a schematic structural diagram of a back-contact solar cell provided by the related art, as Figure 1 shown, the back-contact solar cell includes a first substrate 1, a third doping layer 2 and a fourth doping layer 3. The first substrate 1 includes a front surface 103 and a back surface 104. The third doping layer 2 and the fourth doping layer 3 are alternately arranged on the back surface 104 of the first substrate 1. An insulating isolation region 4 is provided between the third doping layer 2 and the fourth doping layer 3. The two side walls of the insulating isolation region 4 are vertical side walls. The above morphology cannot make good use of sunlight, resulting in a low photoelectric conversion efficiency of the solar cell.

[0064] To solve the above problems, the technical solutions of the embodiments of the present invention are as follows:

[0065] Figure 2 is a schematic structural diagram of a solar cell provided by an embodiment of the present invention, Figure 3 is a scanning electron microscope (SEM) image of the inclined side wall of an isolation region provided by an embodiment of the present invention, as Figure 2 and Figure 3As shown, the solar cell includes: a substrate 10, the substrate 10 including a first surface 101 and a second surface 102 that are oppositely arranged. A first doping layer 11 and a second doping layer 12 are alternately arranged on the first surface 101. The first doping layer 11 and the adjacent second doping layer 12 are separated by a isolation region 13. The conduction types of the first doping layer 11 and the second doping layer 12 are different; the conduction type of the first doping layer 11 is different from that of the substrate 10. The first doping layer 11 includes a first doping portion 111, and the first doping portion 111 is located on the first surface 101. The two sidewalls of the isolation region 13 are inclined sidewalls, and a light trapping structure is provided in a first partial region of the inclined sidewalls. The light trapping structure includes a plurality of zigzag structures 1311. The first doping layer 11 further includes: a second doping portion 112. The solar cell further includes an extension portion 15, and the extension portion 15 extends from the first doping layer 11 towards the isolation region 13; the vertical projection of the extension portion 15 on the first surface 101 covers a part of the vertical projection of the inclined sidewalls on the first surface 101. The extension portion 15 includes the second doping portion 112; the tooth tips of the zigzag structures 1311 on the inclined sidewalls close to the first doping layer 11 are in contact with the extension portion 15.

[0066] Specifically, the substrate 10 includes a first surface 101 and a second surface 102. Exemplarily, the first surface 101 can be the back surface (non-light-receiving surface), and the second surface 102 can be the front surface (light-receiving surface).

[0067] The first doping layer 11 and the second doping layer 12 are alternately arranged on the first surface 101 along a first direction X. The doping types of the first doping layer 11 and the second doping layer 12 are different. The first direction X is the direction in which the first doping layer 11 points to the isolation region 13.

[0068] The doping type of the first doping layer 11 is different from that of the substrate 10. The doping type of the second doping layer 12 is the same as that of the substrate 10, and the doping concentration of the second doping layer 12 is greater than that of the substrate 10. Exemplarily, the substrate 10 can be an N-type substrate, the first doping layer 11 can be a P-type doping layer, and the second doping layer 12 can be an N-type doping layer. Or, the substrate 10 can be a P-type substrate, the first doping layer 11 can be an N-type doping layer, and the second doping layer 12 can be a P-type doping layer.

[0069] In some embodiments of the present invention, the doping type of the second doping layer 12 can be different from that of the substrate 10, the doping type of the first doping layer 11 can be the same as that of the substrate 10, and the doping concentration of the first doping layer 11 is greater than that of the substrate 10. Exemplarily, the substrate 10 can be an N-type substrate, the first doping layer 11 can be an N-type doping layer, and the second doping layer 12 can be a P-type doping layer. Or, the substrate 10 can be a P-type substrate, the first doping layer 11 can be a P-type doping layer, and the second doping layer 12 can be an N-type doping layer.

[0070] The first doping layer 11 includes a first doping portion 111 and a second doping portion 112. The second doping portion 112 extends from the first doping portion 111 towards the isolation region 13. The extension portion 15 may include the second doping portion 112. In some embodiments of the present invention, the extension portion 15 may further include other film layers in addition to the second doping portion 112 ( Figure 2 not shown in the figure). The isolation region 13 may extend into the substrate 10. The isolation region 13 includes a first inclined sidewall 131 and a second inclined sidewall 132. A light trapping structure composed of a plurality of zigzag structures 1311 is provided in a first partial region of the first inclined sidewall 131, and the tooth tips of the zigzag structures 1311 on the first inclined sidewall 131 close to the first doping layer 11 are in contact with the extension portion 15. The zigzag structures 1311 can play a supporting role for the extension portion 15. In some embodiments of the present invention, a light trapping structure composed of a plurality of zigzag structures 1311 may also be provided in a first partial region of the second inclined sidewall 132.

[0071] Figure 2 The black straight line with a one-way arrow in the figure represents the optical path of the incident light irradiating the surface of the extension portion 15 including the second doping portion 112 close to the first inclined sidewall 131. When the incident light irradiates the surface of the extension portion 15 including the second doping portion 112 close to the first inclined sidewall 131, according to the optical path shown, the extension portion 15 including the second doping portion 112 can be referred to as a "brim structure", which can directly reflect the light to the light trapping structure of the first inclined sidewall 131.

[0072] In the technical solution of the embodiment of the present invention, the two side walls of the isolation region 13 are inclined side walls. A light trapping structure composed of a plurality of zigzag structures 1311 is provided in a first partial region of the first inclined side wall 131. The two side walls of the isolation region 13 are the first surface 101 of the substrate 10, that is, the light trapping structure can increase the surface area of the first inclined side wall 131 in the first surface 101, increase the contact area between the first surface 101 and the light irradiated onto the first surface 101, and enable the first inclined side wall 131 of the first surface 101 to have a high light trapping effect. When the incident light irradiates the first inclined side wall 131 of the isolation region 13, the light trapping structure can effectively increase light trapping and reduce the reflection of the incident light, thereby improving the light absorption of the solar cell and the utilization rate of light by the solar cell, and increasing the current density of the solar cell. The technical solution of the embodiment of the present invention effectively improves the current and carrier transport efficiency of the battery, and finally obtains a solar cell with a high conversion efficiency. At the same time, by providing the second doping portion 112, the reflection of the incident light can be effectively increased, and the incident light is reflected to the light trapping structure composed of a plurality of zigzag structures 1311, thereby further improving the light absorption of the solar cell and the utilization rate of light by the solar cell, and increasing the current density of the solar cell. Moreover, the tooth tips of the zigzag structures 1311 on the first inclined side wall 131 close to the first doping layer 11 are in contact with the extension portion 15. The zigzag structures 1311 can support the extension portion 15, prevent the second doping portion 112 from falling off, and further prevent the solar cell from short-circuiting.

[0073] Optionally, on the basis of the above embodiments, continue to refer to Figure 2 and Figure 3 , the light trapping structure includes a plurality of zigzag structures 1311 arranged in a stacked manner.

[0074] It should be noted that for the plurality of zigzag structures 1311 arranged in a stacked manner, the stacking direction is not limited to one direction. Exemplarily, the stacking direction can be the S1 direction, the S2 direction, or the S3 direction. Adjacent two zigzag structures 1311 overlap in a certain direction, and this direction can be called their stacking direction. The S1 direction refers to the direction from the second surface 102 to the first surface 101, the S2 direction refers to the direction parallel to the surface where the first inclined side wall 131 is located, and the S3 direction refers to the direction from the first inclined side wall 131 to the isolation region 13.

[0075] Specifically, a first partial region of the first inclined sidewall 131 may be provided with a light trapping structure composed of a plurality of stacked zigzag structures 1311. The light trapping structure can increase the surface area of the first inclined sidewall 131 in the first surface 101, increase the contact area between the first surface 101 and the light irradiated onto the first surface 101, and enable the first inclined sidewall 131 of the first surface 101 to have a high light trapping effect. When the incident light irradiates the first inclined sidewall 131 of the isolation region 13, the light trapping structure can effectively increase the light trapping and reduce the reflection of the incident light, thereby improving the light absorption of the solar cell and the utilization rate of light by the solar cell, and increasing the current density of the solar cell. Moreover, the tooth tops of the plurality of stacked zigzag structures 1311 on the first inclined sidewall 131 are in contact with the extension portion 15, and the zigzag structure 1311 can support the extension portion 15, preventing the second doping portion 112 from falling off, and further avoiding the short-circuit problem of the solar cell.

[0076] Optionally, on the basis of the above embodiments, continue to refer to Figure 2 and Figure 3 , the tooth top of the zigzag structure 1311 includes a first side surface F1 and a second side surface F2, and the included angle θ between the first side surface F1 and the second side surface F2 is greater than or equal to 70° and less than or equal to 110°.

[0077] Specifically, the tooth top of the zigzag structure 1311 may include a first side surface F1 and a second side surface F2, and the included angle θ between the first side surface F1 and the second side surface F2 may be set to 70° - 110°. The plurality of zigzag structures 1311 form a light trapping structure, which can increase the surface area of the first inclined sidewall 131 in the first surface 101 of the substrate 10, increase the contact area between the first surface 101 and the light irradiated onto the first surface 101, and enable the first surface 101 to have a high light trapping effect. When the incident light irradiates the first inclined sidewall 131 of the isolation region 13, the light trapping structure can effectively increase the light trapping and reduce the reflection of the incident light, thereby improving the light absorption of the solar cell and the utilization rate of light by the solar cell, and increasing the current density of the solar cell.

[0078] If the degree of the included angle θ between the first side surface F1 and the second side surface F2 is too large, the area of the second doping portion 112 that plays a reflection role will be too small, resulting in poor effect of the second doping portion 112 in reflecting the light to the first inclined sidewall 131. If the degree of the included angle θ between the first side surface F1 and the second side surface F2 is too small, the contact area between the tooth top of the zigzag structure 1311 and the extension portion 15 is too small, resulting in poor supporting effect of the zigzag structure 1311 on the extension portion 15.

[0079] Optionally, on the basis of the above embodiments, continue to refer to Figure 2 and Figure 3, the tooth crest of the serrated structure 1311 includes a first side surface F1 and a second side surface F2. The first side surface F1 can extend to the bottom of the isolation region 13, and the second side surface F2 can extend to the middle of the inclined sidewall. The middle of the inclined sidewall is located between the extension portion 15 and the bottom of the isolation region 13. Alternatively, the first side surface F1 can extend to the bottom of the isolation region 13, and the second side surface F2 can also extend to the bottom of the isolation region 13. Alternatively, the first side surface F1 can extend to the middle of the inclined sidewall, and the second side surface F2 can extend to the middle of the inclined sidewall. The middle of the inclined sidewall is located between the extension portion 15 and the bottom of the isolation region 13.

[0080] Specifically, one side surface of the tooth crest of the serrated structure 1311 can extend to the bottom of the isolation region 13 or the middle of the first inclined sidewall 131, and the other side surface can also extend to the bottom of the isolation region 13 or the middle of the first inclined sidewall 131. The first inclined sidewall 131 and / or the bottom of the isolation region 13 support the serrated structure 1311 to form a light-trapping structure. The light-trapping structure can increase the surface area of the first inclined sidewall 131 in the first surface 101 of the substrate 10, increase the contact area between the first surface 101 and the light irradiated onto the first surface 101, and enable the first surface 101 to have a high light-trapping effect. When the incident light irradiates the first inclined sidewall 131 of the isolation region 13, the light-trapping structure can effectively increase the light trapping, reduce the reflection of the incident light, thereby improving the light absorption of the solar cell, improving the light utilization rate of the solar cell, and increasing the current density of the solar cell.

[0081] Optionally, based on the above embodiments, continue to refer to Figure 2 and Figure 3 , there is a spacing between the tooth crests of two adjacent serrated structures 1311.

[0082] Specifically, there is a spacing D1 between the tooth crests of two adjacent serrated structures 1311. The tooth crests of multiple serrated structures 1311 are in contact with different regions of the extension portion 15. The serrated structure 1311 can support the extension portion 15 to prevent the second doping portion 112 from falling off, thereby avoiding the short-circuit problem of the solar cell. Multiple serrated structures 1311 form a light-trapping structure. The light-trapping structure can increase the surface area of the first inclined sidewall 131 in the first surface 101 of the substrate 10, increase the contact area between the first surface 101 and the light irradiated onto the first surface 101, and enable the first surface 101 to have a high light-trapping effect. When the incident light irradiates the first inclined sidewall 131 of the isolation region 13, the light-trapping structure can effectively increase the light trapping, reduce the reflection of the incident light, thereby improving the light absorption of the solar cell, improving the light utilization rate of the solar cell, and increasing the current density of the solar cell.

[0083] Optionally, based on the above embodiments, continue to refer to Figure 2 and Figure 3 , the distance between the tops of adjacent zigzag structures 1311 is 0.1 um - 3 um.

[0084] Specifically, there is a distance D1 between the tops of adjacent zigzag structures 1311, and the distance D1 can be set to 0.1 um - 3 um. The tops of multiple zigzag structures 1311 are in contact with different regions of the extension part 15. The zigzag structures 1311 can support the extension part 15, preventing the second doping part 112 from falling off, and thus avoiding short - circuit problems in the solar cell. There is a distance D1 between adjacent zigzag structures 1311, and the distance D1 is 0.1 um - 3 um, which can ensure that most regions of the extension part 15 are in contact with the tops of multiple zigzag structures 1311, and the zigzag structures 1311 can support the extension part 15 well.

[0085] The distance D1 between the tops of adjacent zigzag structures 1311 cannot be set too large. If the distance D1 between adjacent stacked zigzag structures 1311 is set too large, it will not be able to support the extension part 15 well.

[0086] Optionally, based on the above embodiments, continue to refer to Figure 2 and Figure 3 , along the extension direction of the extension part 15, the tops of multiple zigzag structures 1311 are distributed between the starting position A1 and the ending position A2 of the extension part 15. Preferably, based on the above embodiments, continue to refer to Figure 2 and Figure 3 , along the extension direction of the extension part 15, there is a distance between the starting position A1 of the extension part 15 and the tops of the zigzag structures 1311.

[0087] Specifically, the intersection point of the first inclined sidewall 131 and the first surface 101 can be called the starting position A1 of the extension part 15. The edge of the extension part 15 close to the isolation region 13 can be called the ending position A2 of the extension part 15.

[0088] In the above solution, for the part where the tops of multiple zigzag structures 1311 do not contact the intersection point of the first inclined sidewall 131 and the first surface 101, the tops of multiple zigzag structures 1311 are fully used to support the extension part 15, so that the tops of multiple zigzag structures 1311 have a good supporting effect on the edge of the extension part 15 far from the first doping part 111, which can prevent the second doping part 112 from falling off, and thus avoid short - circuit problems in the solar cell.

[0089] The positional relationship between the second doping part 112 and the first doping part 111 includes the following three cases:

[0090] Optionally, based on the above embodiments, continue to refer to Figure 2 , the second doping portion 112 and the first doping portion 111 are integrally provided.

[0091] Optionally, based on the above embodiments, Figure 4 is a schematic structural view of another solar cell provided by an embodiment of the present invention. As Figure 4 shown, the second doping portion 112 and the first doping portion 111 are spaced apart.

[0092] Optionally, based on the above embodiments, Figure 5 is a top view of a first doping layer provided by an embodiment of the present invention. As Figure 5 shown, holes are provided in the portion where the second doping portion 112 and the first doping portion 111 are connected.

[0093] Specifically, the first doping portion 111 and the second doping portion 112 can be connected. The tooth tops of the plurality of stacked zigzag structures 1311 can support the extension portion 15 containing the second doping portion 112, thereby preventing the second doping portion 112 from disconnecting from the first doping portion 111, avoiding the second doping portion 112 from falling off, and further avoiding the short-circuit problem of the solar cell. Or, even if the first doping portion 111 and the second doping portion 112 are not connected, the presence of the tooth tops of the plurality of stacked zigzag structures 1311 can support the extension portion 15 containing the second doping portion 112, thereby avoiding the second doping portion 112 from falling off and further avoiding the short-circuit problem of the solar cell.

[0094] Optionally, based on the above embodiments, Figure 6 is a schematic structural view of yet another solar cell provided by an embodiment of the present invention. As Figure 6 shown, the solar cell further includes a passivation layer 14. The passivation layer 14 surrounds the second doping portion 112, and the extension portion 15 includes the second doping portion 112 and the passivation layer 14.

[0095] Specifically, the solar cell may further include a passivation layer 14, which is used to protect the substrate 10, the first doping layer 11, and the second doping layer 12, and prevent the performance of the solar cell from being affected by the external environment. Optionally, the passivation layer 14 includes a film layer of aluminum oxide and / or silicon nitride. The extension portion 15 may include a second doping portion 112 and the passivation layer 14. The tooth tips of the serrated structure 1311 of the first inclined sidewall 131 may be in contact with the second doping portion 112 and the passivation layer 14. In some embodiments of the present invention, the passivation layer 14 may further cover the entire surface of the second doping portion 112 close to the first surface 101. At this time, the tooth tips of the serrated structure 1311 may only be in contact with the passivation layer 14. The serrated structure 1311 of the first inclined sidewall 131 may support the extension portion 15.

[0096] The second doping portion 112 and the passivation layer 14 may be collectively referred to as a "brim structure", which can directly reflect light to the light trapping structure of the first inclined sidewall 131. It can effectively increase the reflection of incident light, reflect the incident light to the light trapping structure formed by a plurality of serrated structures 1311, thereby further improving the light absorption of the solar cell, improving the light utilization rate of the solar cell, and increasing the current density of the solar cell.

[0097] Optionally, based on the above embodiments, Figure 7 is a schematic structural diagram of another solar cell provided by an embodiment of the present invention. As Figure 7 shown, a portion of the substrate 10 close to the first surface 101 extends into the isolation region 13 in the direction pointing from the first doping layer 11 to the isolation region 13 to form a reflection portion 105. The solar cell further includes a passivation layer 14, and the passivation layer 14 surrounds the reflection portion 105 and the second doping portion 112. The extension portion 15 includes the second doping portion 112, the reflection portion 105, and the passivation layer 14.

[0098] Specifically, the reflection portion 105 is located at a portion of the first inclined sidewall 131 close to the connection portion of the first doping portion 111 and the second doping portion 112. The passivation layer 14, the second doping portion 112, and the reflection portion 105 may be collectively referred to as a "brim structure", which can directly reflect light to the light trapping structure of the first inclined sidewall 131. It can effectively increase the reflection of incident light, reflect the incident light to the light trapping structure formed by a plurality of serrated structures 1311, thereby further improving the light absorption of the solar cell, improving the light utilization rate of the solar cell, and increasing the current density of the solar cell.

[0099] The tooth tips of the serrated structure 1311 on the first inclined sidewall 131 are in contact with the passivation layer 14 and the second doping portion 112, and the serrated structure 1311 can support the extension portion 15. In some embodiments of the present invention, the passivation layer 14 may cover the side of the second doping portion 112 close to the first inclined sidewall 131. At this time, the tooth tips of the serrated structure 1311 are in contact with the passivation layer 14, and the serrated structure 1311 can support the extension portion 15.

[0100] Furthermore, the tooth tips of the serrated structure 1311 on the first inclined sidewall 131 may be distributed between the termination positions of the reflection portion 105 and the extension portion 15.

[0101] Optionally, on the basis of the above embodiments, Figure 8 is a schematic structural diagram of another solar cell provided by an embodiment of the present invention. As Figure 8 shown, the solar cell further includes a first tunneling layer 16 located between the reflection portion 105 and the second doping portion 112. The extension portion 15 includes the second doping portion 112, the first tunneling layer 16, the reflection portion 105, and the passivation layer 14.

[0102] Specifically, the solar cell may further include a first tunneling layer 16 on the side of the first doping layer 11 close to the first surface 101. The first tunneling layer 16 may be one or a combination of a tunneling oxide layer (such as a tunneling silicon oxide layer), an intrinsic silicon carbide layer, and an intrinsic amorphous silicon layer, and is not specifically limited herein.

[0103] The second doping portion 112, the first tunneling layer 16, the reflection portion 105, and the passivation layer 14 together constitute the extension portion 15. The tooth tips of the serrated structure 1311 can be in contact with the passivation layer 14 and the first tunneling layer 16, and the serrated structure 1311 can support the extension portion 15. In some embodiments of the present invention, the passivation layer 14 may cover the side of the first tunneling layer 16 close to the first inclined sidewall 131. At this time, the tooth tips of the serrated structure 1311 are in contact with the passivation layer 14, and the serrated structure 1311 can support the extension portion 15.

[0104] The second doping portion 112, the first tunneling layer 16, the reflection portion 105, and the passivation layer 14 may be collectively referred to as a "brim structure", which can directly reflect light to the light trapping structure on the first inclined sidewall 131. It can effectively increase the reflection of incident light, reflect the incident light to the light trapping structure composed of multiple stacked serrated structures 1311, thereby further improving the light absorption of the solar cell, improving the light utilization rate of the solar cell, and increasing the current density of the solar cell.

[0105] Optionally, on the basis of the above embodiments, Figure 9It is a schematic structural diagram of another solar cell provided by an embodiment of the present invention. Figure 10 It is a schematic structural diagram of another solar cell provided by an embodiment of the present invention. As Figure 9 shown, the top of the serrated structure 1311 on the inclined sidewall close to the first doping layer 11 contacts the passivation layer 14. As Figure 6 shown, the top of the serrated structure 1311 on the inclined sidewall close to the first doping layer 11 contacts the passivation layer 14 and the second doping portion 112. As Figure 10 shown, the top of the serrated structure 1311 on the inclined sidewall close to the first doping layer 11 contacts the passivation layer 14, the first tunneling layer 16, and the second doping portion 112. As Figure 8 shown, the top of the serrated structure 1311 on the inclined sidewall close to the first doping layer 11 contacts the passivation layer 14 and the first tunneling layer 16.

[0106] Specifically, as Figure 9 shown, the solar cell may include an extension portion 15 composed of a passivation layer 14, a reflection portion 105, a first tunneling layer 16, and a second doping portion 112, and the passivation layer 14 covers one side of the first tunneling layer 16 close to the first inclined sidewall 131. At this time, the top of the serrated structure 1311 contacts the passivation layer 14.

[0107] As Figure 6 shown, the solar cell may include an extension portion 15 composed of a passivation layer 14 and a second doping portion 112, and the passivation layer 14 only covers a partial area of one side of the second doping portion 112 close to the first inclined sidewall 131. At this time, the top of the serrated structure 1311 contacts the passivation layer 14 and the second doping portion 112. The passivation layer 14 and the second doping portion 112 can be collectively referred to as a "brim structure", and both the passivation layer 14 and the second doping portion 112 can directly reflect light to the light trapping structure of the first inclined sidewall 131. It can effectively increase the reflection of incident light, reflect the incident light to the light trapping structure composed of multiple serrated structures 1311 arranged in a stacked manner, thereby further improving the light absorption of the solar cell and the utilization rate of light by the solar cell, and increasing the current density of the solar cell.

[0108] It should be noted that the solar cell may include an extension portion 15 composed of a passivation layer 14, a second doping portion 112, and a first tunneling layer. The first tunneling layer is located on the side of the first doping layer 11 close to the first surface 101, and the first tunneling layer only covers a partial area of the second doping portion 112 close to the first inclined sidewall 131. Other areas of the second doping portion 112 not covered by the first tunneling layer may be covered by the passivation layer 14, and the top of the serrated structure 1311 can pass through the passivation layer 14 and contact the second doping portion 112.

[0109] AsFigure 10 As shown, the solar cell may include an extension portion 15 composed of a passivation layer 14, a first tunneling layer 16, a second doping portion 112, and a reflection portion 105. The passivation layer 14 and the first tunneling layer 16 only cover a partial area of one side of the second doping portion 112 close to the first inclined sidewall 131. At this time, the tooth top of the zigzag structure 1311 contacts the passivation layer 14, the first tunneling layer 16, and the second doping portion 112. The passivation layer 14, the first tunneling layer 16, the second doping portion 112, and the reflection portion 105 may be collectively referred to as a "brim structure". Both the passivation layer 14 and the second doping portion 112 can directly reflect light to the light trapping structure of the first inclined sidewall 131. It can effectively increase the reflection of incident light, reflect the incident light to the light trapping structure composed of a plurality of stacked zigzag structures 1311, thereby further improving the light absorption of the solar cell, improving the light utilization rate of the solar cell, and increasing the current density of the solar cell.

[0110] As Figure 8 shown, the solar cell may include an extension portion 15 composed of a passivation layer 14, a first tunneling layer 16, a second doping portion 112, and a reflection portion 105. The first tunneling layer 16 is disposed on one side of the second doping portion 112 close to the first inclined sidewall 131. The passivation layer 14 only covers a partial area of one side of the first tunneling layer 16 close to the first inclined sidewall 131. At this time, the tooth top of the zigzag structure 1311 contacts the passivation layer 14 and the first tunneling layer 16. The passivation layer 14, the first tunneling layer 16, the second doping portion 112, and the reflection portion 105 may be collectively referred to as a "brim structure". Both the passivation layer 14 and the first tunneling layer 16 can directly reflect light to the light trapping structure of the first inclined sidewall 131. It can effectively increase the reflection of incident light, reflect the incident light to the light trapping structure composed of a plurality of stacked zigzag structures 1311, thereby further improving the light absorption of the solar cell, improving the light utilization rate of the solar cell, and increasing the current density of the solar cell.

[0111] Optionally, on the basis of the above embodiments, continue to refer to Figures 2 - 10 , the zigzag structure 1311 includes a plurality of protruding portions with different protruding heights in the second direction Y, and the second direction Y is the direction from the first surface 101 to the second surface 102; the protruding portion in contact with the extension portion 15 is the tooth top of the zigzag structure 1311. The adjacent protruding portions are stacked.

[0112] Specifically, the zigzag structure 1311 includes a plurality of protruding portions with different protruding heights in the second direction Y. The protruding portion in contact with the extension portion 15 is the tooth top of the zigzag structure 1311, and the protruding portion can support the extension portion 15.

[0113] Optionally, on the basis of the above embodiments, Figure 11It is a schematic structural diagram of another solar cell provided by an embodiment of the present invention. Figure 12 It is a Figure 3 magnified view of the AA area in Figure 13 It is a Figure 12 magnified view of the BB area in Figure 11 In the schematic structural diagram of the solar cell shown, due to the problem of the section angle, the first light-trapping structure of the first inclined sidewall 131 is not shown. As shown in Figure 3 and Figures 11 - 13 shown, the reflecting portion 105 is located on the second partial area of the inclined sidewall near the connection portion of the first doping portion 111 and the second doping portion 112; the vertical projection of the reflecting portion 105 on the first surface 101 is located within the vertical projection of the second doping portion 112 on the first surface 101.

[0114] Specifically, the reflecting portion 105 can be disposed on the first inclined sidewall 131 near the connection portion of the first doping portion 111 and the second doping portion 112. The reflecting portion 105 can be disposed on the second partial area of the first inclined sidewall 131, while Figures 2 - 10 the light-trapping structure formed by the plurality of serrated structures 1311 shown in

[0115] Figure 11 and Figure 13 can be disposed on the first partial area of the first inclined sidewall 131, and the first partial area and the second partial area can be different areas.

[0116] In

[0117] Figures 11 - 13 shown, the black straight lines with arrows represent the light paths that irradiate the extension portion 15 including the second doping portion 112 and are reflected to the first inclined sidewall 131 via the reflecting portion 105, or directly reflect the incident light into the interior of the solar cell. The extension portion 15 including the second doping portion 112 can be called a "brim structure", which can reflect the light via the reflecting portion 105, and the reflecting portion 105 reflects the light to the first inclined sidewall 131 and enters the interior of the solar cell, avoiding the light from entering the gap between the connection portion of the second doping portion 112 and the first doping portion 111 and the first inclined sidewall 131 and being unable to enter the interior of the solar cell. It should be noted that the light entering the gap between the connection portion of the second doping portion 112 and the first doping portion 111 and the first inclined sidewall 131 is equivalent to the light propagating parallel to the first surface 101, so it cannot enter the interior of the solar cell.

[0116] In summary, the side of the reflecting portion 105 close to the isolation region 13 can reflect part of the incident light into the interior of the solar cell, thereby improving the light absorption of the solar cell, increasing the light utilization rate of the solar cell, and increasing the current density of the solar cell.

[0117] Optionally, on the basis of the above embodiments, continue to refer to Figures 11 - 13The angle α between a surface of the reflecting portion 105 close to the isolation region 13 and the inclined side wall is in the range of 90°-120°.

[0118] Specifically, when the contact area between the reflecting portion 105 and the extending portion 15 remains unchanged, if the angle α between the side of the reflecting portion 105 close to the isolation region 13 and the first inclined side wall 131 is too small, the volume of the reflecting portion 105 located on the first inclined side wall 131 will be too small, and the incident light irradiated to the reflecting portion 105 will not be effectively reflected to the interior of the solar cell, thereby failing to effectively improve the absorption of light by the solar cell, improve the utilization rate of light by the solar cell, and increase the current density of the solar cell.

[0119] When the contact area between the reflecting portion 105 and the extending portion 15 remains unchanged, if the angle α between the side of the reflecting portion 105 close to the isolation region 13 and the first inclined side wall 131 is too large, the volume of the reflecting portion 105 located on the first inclined side wall 131 will be too large, and the area of ​​the first inclined side wall 131 occupied will be too large, which will correspondingly reduce the area of ​​the first inclined side wall 131 that can be contacted by the sawtooth structure 1311, which is not conducive to the light trapping structure formed by the sawtooth structure 1311 to effectively increase the surface area of ​​the first inclined side wall 131.

[0120] Optionally, based on the above embodiments, continue to refer to Figure 2 , Figures 4 - 11 The angle between the inclined side wall close to the first doping layer 11 and the surface of the first doping portion 111 close to the substrate 10 is an obtuse angle.

[0121] Specifically, the angle between the first inclined sidewall 131 close to the first doping layer 11 and the side of the first doping portion 111 close to the substrate 10 is an obtuse angle, and the first inclined sidewall 131 close to the first doping layer 11 protrudes toward the isolation region 13. The first inclined sidewall 131 close to the first doping layer 11 is provided with a light trapping structure composed of a plurality of sawtooth structures 1311, and the light trapping structure can increase the surface area of ​​the first surface 101 of the substrate 10, increase the contact area between the first surface 101 and the light irradiated to the first surface 101, and make the first surface 101 have a higher light trapping effect. When the incident light irradiates the first inclined sidewall 131 of the isolation region 13, the light trapping structure can effectively increase the light trapping and reduce the reflection of the incident light, thereby improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell.

[0122] Optionally, based on the above embodiments, continue to refer to Figure 2 and Figure 4, an isolation region 13 is provided with an isolation groove, and the isolation groove includes a connected first sub-groove 134 and a second sub-groove 135. The first sub-groove 134 extends from the surface of the first doping layer 11 away from the substrate 10 to the first surface 101. The second sub-groove 135 extends from the first surface 101 into the interior of the substrate 10. The inclined sidewall is the sidewall of the second sub-groove 135.

[0123] Specifically, the sidewall of the second sub-groove 135 includes a first inclined sidewall 131 and a second inclined sidewall 132. A light trapping structure composed of a plurality of serrated structures 1311 is provided in a first partial region of the first inclined sidewall 131. The light trapping structure can increase the surface area of the first surface 101 of the substrate 10, increase the contact area between the first surface 101 and the light irradiated onto the first surface 101, and enable the first surface 101 to have a high light trapping effect. When the incident light irradiates the first inclined sidewall 131 of the isolation region 13, the light trapping structure can effectively increase light trapping, reduce the reflection of the incident light, thereby improving the light absorption of the solar cell and the utilization rate of light by the solar cell, and increasing the current density of the solar cell.

[0124] Optionally, on the basis of the above embodiments, Figure 14 is a schematic structural diagram of another solar cell provided by an embodiment of the present invention. As Figure 14 shown, the second doping layer 12 includes a third doping portion 121, and the third doping portion 121 is located on the first surface 101; a light trapping structure is provided in a first partial region of the second inclined sidewall 132 of the isolation region 13, and the light trapping structure includes a plurality of serrated structures 1311 stacked. The second doping layer 12 further includes: a fourth doping portion 122; the solar cell further includes an extension portion 15 close to the second inclined sidewall 132, and the extension portion 15 extends along the second doping layer 12 towards the isolation region 13; the vertical projection of the extension portion 15 close to the second inclined sidewall 132 on the first surface 101 covers a part of the vertical projection of the second inclined sidewall 132 on the first surface 101. The extension portion 15 close to the second inclined sidewall 132 includes the fourth doping portion 122; the tooth tips of the serrated structures 1311 on the second inclined sidewall 132 close to the second doping layer 12 are in contact with the extension portion 15 close to the second inclined sidewall 132.

[0125] The extension portion 15 including the fourth doping portion 122 can be called a "brim structure", which can directly reflect light to the light trapping structure of the second inclined sidewall 132.

[0126] In the technical solution of the embodiment of the present invention, a light trapping structure composed of a plurality of stacked zigzag structures 1311 is provided in a first partial area of the second inclined sidewall 132. The second inclined sidewall 132 of the isolation region 13 is the first surface 101 of the substrate 10. That is, the light trapping structure can increase the surface area of the second inclined sidewall 132 in the first surface 101, increase the contact area between the first surface 101 and the light irradiated onto the first surface 101, and enable the second inclined sidewall 132 of the first surface 101 to have a high light trapping effect. When the incident light irradiates the second inclined sidewall 132 of the isolation region 13, the light trapping structure can effectively increase light trapping and reduce the reflection of the incident light, thereby improving the light absorption of the solar cell and the utilization rate of light by the solar cell, and increasing the current density of the solar cell. The technical solution of the embodiment of the present invention effectively improves the current and carrier transport efficiency of the battery, and finally obtains a solar cell with a high conversion efficiency. At the same time, by providing the fourth doping portion 122, the reflection of the incident light can be effectively increased, and the incident light is reflected to the light trapping structure composed of a plurality of stacked zigzag structures 1311, thereby further improving the light absorption of the solar cell and the utilization rate of light by the solar cell, and increasing the current density of the solar cell. Moreover, the tooth top of the zigzag structure 1311 on the second inclined sidewall 132 close to the second doping layer 12 contacts the extension portion 15 close to the second inclined sidewall 132. The zigzag structure 1311 can support the extension portion 15 close to the second inclined sidewall 132, prevent the fourth doping portion 122 from falling off, and further prevent the solar cell from short-circuiting.

[0127] Optionally, on the basis of the above embodiments, continue to refer to Figure 14 , the tooth top of the zigzag structure 1311 of the second inclined sidewall 132 includes a third side surface F3 and a fourth side surface F4, and the included angle β between the third side surface F3 and the fourth side surface F4 is greater than or equal to 70° and less than or equal to 110°.

[0128] If the degree of the included angle β between the third side surface F3 and the fourth side surface F4 of the tooth top of the zigzag structure 1311 of the second inclined sidewall 132 is too large, the area where the fourth doping portion 122 plays a reflection role will be too small, resulting in poor effect of the fourth doping portion 122 on reflecting the light to the second inclined sidewall 132. If the degree of the included angle β between the third side surface F3 and the fourth side surface F4 of the tooth top of the zigzag structure 1311 of the second inclined sidewall 132 is too small, the contact area between the tooth top of the zigzag structure 1311 of the second inclined sidewall 132 and the extension portion 15 close to the second inclined sidewall 132 is too small, resulting in poor support effect of the zigzag structure 1311 of the second inclined sidewall 132 on the extension portion 15 close to the second inclined sidewall 132.

[0129] Optionally, on the basis of the above embodiments, continue to refer toFigure 14 , the tooth crest of the serrated structure 1311 of the second inclined sidewall 132 includes a third side surface F3 and a fourth side surface F4. The third side surface F3 extends to the bottom of the isolation region 13, and the fourth side surface F4 extends to the middle of the second inclined sidewall 132. The middle of the second inclined sidewall 132 is located between the extension portion 15 near the second inclined sidewall 132 and the bottom of the isolation region 13. Alternatively, the third side surface F3 may extend to the bottom of the isolation region 13, and the fourth side surface F4 may also extend to the bottom of the isolation region 13. Alternatively, the third side surface F3 may extend to the middle of the second inclined sidewall 132, and the fourth side surface F4 may extend to the middle of the second inclined sidewall 132. The middle of the second inclined sidewall 132 is located between the extension portion 15 and the bottom of the isolation region 13.

[0130] Specifically, one side surface of the tooth crest of the serrated structure 1311 of the second inclined sidewall 132 may extend to the bottom of the isolation region 13 or the middle of the second inclined sidewall 132, and the other side surface may also extend to the bottom of the isolation region 13 or the middle of the second inclined sidewall 132. The bottom of the second inclined sidewall 132 and / or the isolation region 13 supports the serrated structure 1311 of the second inclined sidewall 132 to form a light trapping structure with multiple serrated structures 1311 of the second inclined sidewall 132.

[0131] Optionally, based on the above embodiments, continue to refer to Figure 14 , there is a spacing between the tooth crests of two adjacent serrated structures 1311 of the second inclined sidewall 132.

[0132] Specifically, there is a spacing between the tooth crests of two adjacent serrated structures 1311 of the second inclined sidewall 132. The tooth crests of multiple serrated structures 1311 of the second inclined sidewall 132 are in contact with different regions near the extension portion 15 of the second inclined sidewall 132. The serrated structure 1311 of the second inclined sidewall 132 can support the extension portion 15 near the second inclined sidewall 132 to prevent the fourth doping portion 122 from falling off, thereby avoiding short - circuit problems in the solar cell. Optionally, based on the above embodiments, continue to refer to Figure 14 , the spacing between the tooth crests of two adjacent serrated structures 1311 arranged in a stacked manner on the second inclined sidewall 132 is 0.1um - 3um.

[0133] Specifically, there is a spacing between the tooth tops of two adjacent serrated structures 1311 on the second inclined sidewall 132, and the spacing can be set to 0.1um - 3um. The tooth tops of multiple serrated structures 1311 on the second inclined sidewall 132 are in contact with different regions of the extension 15 close to the second inclined sidewall 132. The serrated structures 1311 on the second inclined sidewall 132 can support the extension 15 close to the second inclined sidewall 132, preventing the fourth doped portion 122 from falling off, and thus avoiding short - circuit problems in the solar cell. There is a spacing between two adjacent serrated structures 1311 on the second inclined sidewall 132, and the spacing is 0.1um - 3um, which can ensure that most regions of the extension 15 close to the second inclined sidewall 132 are in contact with the tooth tops of multiple serrated structures 1311 on the second inclined sidewall 132. The serrated structures 1311 on the second inclined sidewall 132 can well support the extension 15 close to the second inclined sidewall 132.

[0134] The spacing between the tooth tops of two adjacent serrated structures 1311 on two second inclined sidewalls 132 arranged in a stacked manner should not be set too large. If the spacing between two adjacent serrated structures 1311 on two second inclined sidewalls 132 arranged in a stacked manner is set too large, it will not be able to provide good support for the extension 15 close to the second inclined sidewall 132.

[0135] Optionally, based on the above embodiments, continue to refer to Figure 14 , along the extension direction of the extension 15 close to the second inclined sidewall 132, the tooth tops of multiple serrated structures 1311 on the second inclined sidewall 132 arranged in a stacked manner are distributed between the starting position B1 and the ending position B2 of the extension 15 close to the second inclined sidewall 132. Preferably, based on the above embodiments, continue to refer to Figure 14 , along the extension direction of the extension 15 close to the second inclined sidewall 132, there is a spacing between the starting position B1 of the extension 15 close to the second inclined sidewall 132 and the tooth tops of the serrated structures 1311 on the second inclined sidewall 132.

[0136] Specifically, the intersection of the second inclined sidewall 132 and the first surface 101 can be referred to as the starting position B1 of the extension 15 close to the second inclined sidewall 132. The edge of the extension 15 close to the second inclined sidewall 132 near the isolation region 13 can be referred to as the ending position B2 of the extension 15 close to the second inclined sidewall 132.

[0137] In the above solution, the parts of the tooth tops of the zigzag structures 1311 of the plurality of stacked second inclined sidewalls 132 that do not contact the intersection of the second inclined sidewall 132 and the first surface 101 are such that the tooth tops of the zigzag structures 1311 of the plurality of stacked second inclined sidewalls 132 are completely used to support the extension 15 close to the second inclined sidewall 132. This enables the tooth tops of the plurality of stacked zigzag structures 1311 to have a good supporting effect on the edge of the extension 15 close to the second inclined sidewall 132 and away from the third doping portion 121, which can prevent the fourth doping portion 122 from falling off, thereby avoiding the problem of short circuit in the solar cell.

[0138] The positional relationship between the fourth doping portion 122 and the third doping portion 121 includes the following three cases:

[0139] Optionally, based on the above embodiments, with continued reference to Figure 14 , the fourth doping portion 122 and the third doping portion 121 are integrally provided. Optionally, based on the above embodiments, the fourth doping portion 122 and the third doping portion 121 are spaced apart. Optionally, based on the above embodiments, holes are provided in the portion where the fourth doping portion 122 and the third doping portion 121 are connected.

[0140] Specifically, the fourth doping portion 122 and the third doping portion 121 can be connected, and the tooth tops of the plurality of stacked zigzag structures 1311 can support the extension 15 containing the fourth doping portion 122, thereby preventing the fourth doping portion 122 from disconnecting from the third doping portion 121, avoiding the fourth doping portion 122 from falling off, and further avoiding the problem of short circuit in the solar cell. Or, even if the third doping portion 121 and the fourth doping portion 122 are not connected, the presence of the tooth tops of the zigzag structures 1311 of the plurality of stacked second inclined sidewalls 132 can support the extension 15 containing the fourth doping portion 122, thereby avoiding the fourth doping portion 122 from falling off and further avoiding the problem of short circuit in the solar cell.

[0141] Optionally, based on the above embodiments, with continued reference to Figure 14 , the solar cell further includes a passivation layer 14. The passivation layer 14 can surround the fourth doping portion 122, and the extension 15 close to the second inclined sidewall 132 includes the fourth doping portion 122 and the passivation layer 14.

[0142] Specifically, the zigzag structure 1311 of the second inclined sidewall 132 can support the extension 15 close to the second inclined sidewall 132 and including the fourth doping portion 122 and the passivation layer 14.

[0143] The fourth doping portion 122 and the passivation layer 14 can be collectively referred to as a "brim structure", which can directly reflect light to the light trapping structure of the second inclined sidewall 132. It can effectively increase the reflection of incident light, so that the incident light is reflected to the light trapping structure formed by the zigzag structures 1311 of the second inclined sidewalls 132 arranged in multiple layers, thereby further improving the light absorption of the solar cell, improving the light utilization rate of the solar cell, and increasing the current density of the solar cell.

[0144] Optionally, on the basis of the above embodiments, continue to refer to Figure 14 , a part of the substrate 10 near the first surface 101 extends in the opposite direction of the first direction X to the isolation region 13 to form a reflection portion 105; the solar cell further includes a passivation layer 14, and the passivation layer 14 wraps the reflection portion 105 and the fourth doping portion 122; the extension portion 15 near the second inclined sidewall 132 includes the fourth doping portion 122, the reflection portion 105 and the passivation layer 14.

[0145] The structure composed of the fourth doping portion 122, the reflection portion 105 and the passivation layer 14 can be collectively referred to as a "brim structure", which can directly reflect light to the light trapping structure of the second inclined sidewall 132. It can effectively increase the reflection of incident light, so that the incident light is reflected to the light trapping structure formed by the zigzag structures 1311 of the second inclined sidewalls 132 arranged in multiple layers, thereby further improving the light absorption of the solar cell, improving the light utilization rate of the solar cell, and increasing the current density of the solar cell. The zigzag structure 1311 of the second inclined sidewall 132 can support the extension portion 15 including the fourth doping portion 122, the reflection portion 105 and the passivation layer 14.

[0146] Furthermore, the tooth tops of the zigzag structures 1311 of the second inclined sidewall 132 can be distributed between the reflection portion 105 and the termination position B2.

[0147] Optionally, on the basis of the above embodiments, continue to refer to Figure 14 , the solar cell further includes a second tunneling layer 17, which is located between the reflection portion 105 and the fourth doping portion 122 near the second inclined sidewall 132; the extension portion 15 near the second inclined sidewall 132 includes the fourth doping portion 122, the second tunneling layer 17, the reflection portion 105 and the passivation layer 14.

[0148] Specifically, the solar cell may further include a second tunneling layer 17 on the side of the second doping layer 12 near the first surface 101. The second tunneling layer 17 may be one or a combination of a tunneling oxide layer (such as a tunneling silicon oxide layer), an intrinsic silicon carbide layer, and an intrinsic amorphous silicon layer, which is not specifically limited herein.

[0149] The serrated structure 1311 of the second inclined sidewall 132 can support the extension portion 15 including the fourth doping portion 122, the second tunneling layer 17, the reflection portion 105, and the passivation layer 14. The fourth doping portion 122, the second tunneling layer 17, the reflection portion 105, and the passivation layer 14 can be collectively referred to as the "brim structure", which can directly reflect light to the light trapping structure of the second inclined sidewall 132. It can effectively increase the reflection of incident light, reflect the incident light to the light trapping structure formed by a plurality of stacked serrated structures 1311, thereby further improving the light absorption of the solar cell, improving the light utilization rate of the solar cell, and increasing the current density of the solar cell.

[0150] Optionally, on the basis of the above embodiments, the top of the serrated structure 1311 on the second inclined sidewall 132 close to the second doping layer 12 is in contact with the passivation layer 14. Or, the top of the serrated structure 1311 on the second inclined sidewall 132 close to the second doping layer 12 is in contact with the passivation layer 14 and the fourth doping portion 122. Or, the top of the serrated structure 1311 on the second inclined sidewall 132 close to the second doping layer 12 is in contact with the passivation layer 14, the second tunneling layer 17, and the fourth doping portion 122. Or, the top of the serrated structure 1311 on the second inclined sidewall 132 close to the second doping layer 12 is in contact with the passivation layer 14 and the second tunneling layer 17.

[0151] Optionally, on the basis of the above embodiments, continue to refer to Figure 14 , the serrated structure 1311 of the second inclined sidewall 132 includes a plurality of protruding portions with different protruding heights in the second direction Y; and the protruding portion in contact with the extension portion 15 close to the second inclined sidewall 132 is the top of the serrated structure 1311 of the second inclined sidewall 132. The adjacent protruding portions are stacked.

[0152] Optionally, on the basis of the above embodiments, continue to refer to Figure 14 , the reflection portion 105 close to the second inclined sidewall 132 is located on the second partial area of the second inclined sidewall 132 near the connection portion of the third doping portion 121 and the fourth doping portion 122. The perpendicular projection of the reflection portion 105 on the first surface 101 is within the perpendicular projection of the fourth doping portion 122 on the first surface 101.

[0153] Specifically, the reflection portion 105 close to the second inclined sidewall 132 can be disposed on the second inclined sidewall 132 near the connection portion of the third doping portion 121 and the fourth doping portion 122. The reflection portion 105 can be disposed in the second partial area of the second inclined sidewall 132, while Figure 14The light trapping structure formed by the zigzag structure 1311 of the second inclined sidewall 132 in the multiple stacked settings shown can be provided in the first partial area of the second inclined sidewall 132, and the first partial area and the second partial area can be different areas.

[0154] The extension 15 including the fourth doping portion 122 can be referred to as a "brim structure", which can reflect light to the inside of the solar cell through the reflection portion 105 near the second inclined sidewall 132. The reflection portion 105 near the second inclined sidewall 132 reflects the light to the second inclined sidewall 132 and into the inside of the solar cell, or directly reflects the incident light to the inside of the solar cell, avoiding the light from entering the gap between the connection of the fourth doping portion 122 and the third doping portion 121 and the second inclined sidewall 132 and thus not being able to enter the inside of the solar cell. It should be noted that the light entering the gap between the connection of the fourth doping portion 122 and the third doping portion 121 and the second inclined sidewall 132 is equivalent to the light propagating parallel to the first surface 101, so it cannot enter the inside of the solar cell.

[0155] In summary, the side of the reflection portion 105 near the second inclined sidewall 132 and close to the isolation region 13 can reflect part of the incident light to the inside of the solar cell, thereby improving the light absorption of the solar cell, increasing the light utilization rate of the solar cell, and increasing the current density of the solar cell.

[0156] Optionally, on the basis of the above embodiments, continue to refer to Figure 14 The included angle range between the side of the reflection portion 105 near the second inclined sidewall 132 and close to the isolation region 13 and the second inclined sidewall 132 is 90° - 120°.

[0157] Specifically, when the contact area between the reflection portion 105 and the extension 15 remains unchanged, if the included angle between the side of the reflection portion 105 near the second inclined sidewall 132 and close to the isolation region 13 and the second inclined sidewall 132 is too small, the volume of the reflection portion 105 located on the second inclined sidewall 132 is too small, and the incident light irradiated on the included angle between the side of the reflection portion 105 near the isolation region 13 and the second inclined sidewall 132 will not be effectively reflected to the inside of the solar cell, thus unable to effectively improve the light absorption of the solar cell, increase the light utilization rate of the solar cell, and increase the current density of the solar cell.

[0158] When the contact area between the reflection part 105 and the extension part 15 remains unchanged, if the degree of the angle between the side of the reflection part 105 close to the isolation area 13 and the second inclined sidewall 132 is too large when the reflection part 105 is close to the second inclined sidewall 132, the volume of the reflection part 105 located on the second inclined sidewall 132 is too large, occupying too much area of the second inclined sidewall 132, correspondingly reducing the area of the second inclined sidewall 132 that the serrated structure 1311 can contact, which is not conducive to the light trapping structure formed by the serrated structure 1311 to effectively increase the surface area of the second inclined sidewall 132.

[0159] Optionally, on the basis of the above embodiments, continue to refer to Figure 14 , the angle between the second inclined sidewall 132 close to the second doping layer 12 and the side of the third doping part 121 close to the substrate 10 is an obtuse angle.

[0160] An embodiment of the present invention provides a battery assembly, wherein the battery assembly includes any solar cell provided in any of the above embodiments of the present invention, and has the beneficial effects of any solar cell provided in any of the above embodiments of the present invention.

[0161] An embodiment of the present invention provides a photovoltaic system, wherein the photovoltaic system includes the battery assembly provided in the above embodiment of the present invention, and has the beneficial effects of the battery assembly provided in the above embodiment of the present invention. Since the battery assembly provided in the embodiment of the present invention has the beneficial effects of any solar cell provided in any of the above embodiments of the present invention, the photovoltaic system provided in the embodiment of the present invention has the beneficial effects of any solar cell provided in any of the above embodiments of the present invention.

[0162] It should be understood that various forms of the processes shown above can be used, steps can be reordered, added or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions of the present invention can be achieved, and no limitations are imposed herein.

[0163] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A solar cell, characterized in that: include: A substrate, the substrate comprising a first surface and a second surface disposed opposite to each other; A first doping layer and a second doping layer are alternately arranged on the first surface, the first doping layer and the adjacent second doping layer are separated by an isolation region, the conductivity type of the first doping layer is different from the conductivity type of the second doping layer; the conductivity type of the first doping layer is different from the conductivity type of the substrate; The first doping layer includes a first doping portion, and the first doping portion is located on the first surface; The two side walls of the isolation region are inclined side walls, and a light trapping structure is disposed in a first portion of the inclined side walls, wherein the light trapping structure includes a plurality of sawtooth structures; The first doping layer further includes: a second doping portion; The solar cell further includes an extension portion, the extension portion extending from the first doping layer toward the isolation region; a vertical projection of the extension portion on the first surface covers a portion of a vertical projection of the inclined sidewall on the first surface; The extension portion includes the second doping portion; the tooth top of the sawtooth structure on the inclined side wall close to the first doping layer contacts the extension portion.

2. The solar cell according to claim 1, characterized in that: The light trapping structure includes a plurality of stacked sawtooth structures.

3. The solar cell according to claim 1, characterized in that The tooth top of the sawtooth structure includes a first side surface and a second side surface, and the included angle between the first side surface and the second side surface is greater than or equal to 70° and less than or equal to 110°.

4. The solar cell according to claim 1, characterized in that There is a spacing between the tooth tops of two adjacent sawtooth structures.

5. The solar cell according to claim 4, characterized in that The spacing between the tooth tops of two adjacent sawtooth structures is 0.1um-3um.

6. The solar cell according to claim 1, characterized in that Along the extending direction of the extending portion, the tooth tops of the plurality of sawtooth structures are distributed between the starting position and the ending position of the extending portion.

7. The solar cell according to claim 6, characterized in that: Along the extending direction of the extending portion, there is a distance between the starting position of the extending portion and the tooth top of the sawtooth structure.

8. The solar cell according to claim 1, characterized in that The second doping portion and the first doping portion are integrally arranged.

9. The solar cell according to claim 1, characterized in that: The second doping portion and the first doping portion are arranged at an interval.

10. The solar cell according to claim 1, characterized in that: A hole is provided at a portion where the second doping portion and the first doping portion are connected.

11. The solar cell according to claim 1, characterized in that: The solar cell further includes a passivation layer surrounding the second doped portion, and the extension portion includes the second doped portion and the passivation layer.

12. The solar cell according to claim 1, characterized in that A portion of the substrate close to the first surface extends to the isolation region along a direction in which the first doping layer points to the isolation region to form a reflection portion; The solar cell further includes a passivation layer, wherein the passivation layer surrounds the reflective portion and the second doped portion; The extending portion includes the second doped portion, the reflective portion, and the passivation layer.

13. The solar cell according to claim 12, characterized in that: It also includes a first tunneling layer located between the reflective portion and the second doped portion; The extension portion includes the second doped portion, the first tunneling layer, the reflective portion, and the passivation layer.

14. The solar cell according to claim 13, characterized in that: The tooth top of the sawtooth structure on the inclined side wall close to the first doping layer is in contact with the passivation layer; Alternatively, the tooth top of the sawtooth structure on the inclined side wall close to the first doping layer is in contact with the passivation layer and the second doping portion; Alternatively, the tooth top of the sawtooth structure on the inclined side wall close to the first doping layer is in contact with the passivation layer, the first tunneling layer and the second doping portion; Alternatively, the tooth tops of the sawtooth structure on the inclined sidewall close to the first doping layer are in contact with the passivation layer and the first tunneling layer.

15. The solar cell according to claim 1, characterized in that The sawtooth structure includes a plurality of protrusions with different protrusion heights in the direction from the first surface to the second surface; the protrusions in contact with the extension portion are the tooth tops of the sawtooth structure; The adjacent protrusions are stacked.

16. The solar cell according to claim 12, characterized in that: The reflective portion is located on a second partial region of the inclined sidewall close to a portion where the first doped portion and the second doped portion are connected; A vertical projection of the reflective portion on the first surface is located within a vertical projection of the second doped portion on the first surface.

17. The solar cell according to claim 16, characterized in that: The angle between a surface of the reflective portion close to the isolation region and the inclined side wall is in the range of 90°-120°.

18. The solar cell according to claim 1, characterized in that An angle between the inclined side wall close to the first doping layer and a surface of the first doping portion close to the substrate is an obtuse angle.

19. The solar cell according to claim 1, characterized in that The isolation area is provided with an isolation groove, and the isolation groove includes a first sub-groove and a second sub-groove connected to each other; The first sub-groove extends from a surface of the first doped layer away from the substrate to the first surface; The second sub-groove extends from the first surface to the inside of the substrate; The inclined side wall is a side wall of the second sub-groove.

20. A battery assembly, characterized in that: A solar cell comprising the solar cell according to any one of claims 1 to 19.

21. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 20.

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