A back-contact solar cell

Abstract

This disclosure relates to the field of solar cell technology and discloses a back-contact solar cell, comprising: a substrate layer including a light-receiving surface and a back-lighting surface disposed opposite to each other; a first doped region and a second doped region, alternately disposed on the back-lighting surface side of the substrate layer along a first direction; both the first doped region and the second doped region extending along a second direction; an isolation groove occupying the space between adjacent first doped regions and second doped regions and extending into the substrate layer; at least one sidewall of the isolation groove includes a plurality of protrusions arranged along the second direction; the protrusions extend from the opening of the isolation groove to the bottom of the isolation groove; each protrusion has a apex protrusion structure composed of a plurality of ridges on its surface; the apex protrusion structure is located on the side of the protrusion structure closest to the isolation groove. This disclosure can reduce parasitic absorption of polycrystalline silicon, increase the coverage area of ​​the passivation layer, improve carrier transport and collection functions, and thus improve the optical and electrical performance of the cell.

Description

Technical Field

[0001] This disclosure relates to the field of solar cell technology, and specifically to a back-contact solar cell. Background Technology

[0002] Back-contact batteries, by moving the front grid lines to the back, not only avoid light-blocking losses from the front grid lines and improve optical performance, but also offer better aesthetics, making them particularly suitable for high-end distributed applications. Currently, parasitic absorption in polysilicon (polycrystalline silicon) is a key factor affecting the improvement of optical performance in back-contact batteries. Reducing the thickness and coverage area of ​​the polysilicon is crucial for reducing parasitic absorption and improving battery optical performance, and is also an important measure for further efficiency improvement. One effective way to reduce the polysilicon coverage area on the back surface is to further increase the width of the isolation region. However, directly increasing the width of the isolation region can lead to two problems: firstly, it can increase the distance that electrons and holes inside the silicon substrate travel to the N-type and P-type doped regions, resulting in poorer carrier transport performance; secondly, it can make the p / n-poly area too small, reducing the collection area for internal carriers and severely degrading the battery's electrical performance.

[0003] Therefore, a solution is needed to reduce parasitic absorption in polycrystalline silicon while ensuring the carrier transport performance of the P-type and N-type doped regions, thereby improving the optical performance of the battery while also taking into account its electrical performance. Utility Model Content

[0004] In view of this, the present disclosure provides a back-contact solar cell to solve the problems of high parasitic absorption caused by the large coverage area of ​​the polycrystalline silicon layer in the first and second doped regions of existing back-contact solar cells, which in turn leads to poor optical performance of the back-contact solar cell, and the problem that directly increasing the width of the isolation region will reduce the electrical performance of the cell.

[0005] In a first aspect, this disclosure provides a back-contact solar cell, comprising:

[0006] The base layer includes a light-receiving surface and a backlighting surface that are positioned opposite to each other;

[0007] The first doped region and the second doped region are alternately disposed on one side of the back surface of the substrate along the first direction; both the first doped region and the second doped region extend along the second direction.

[0008] An isolation groove occupies the space between adjacent first and second doped regions and extends into the substrate layer; the isolation groove separates adjacent first and second doped regions.

[0009] At least one sidewall of the isolation groove includes a plurality of protrusions arranged along a second direction; the protrusions extend from the opening of the isolation groove to the bottom of the isolation groove.

[0010] Each raised structure has a apex protrusion structure composed of multiple ridges on its surface; the apex protrusion structure is located on the side of the raised structure closest to the isolation groove.

[0011] Beneficial effects: The back-contact solar cell provided by this disclosure, on the one hand, includes at least one sidewall of the isolation groove comprising a plurality of protrusions arranged along a second direction. These protrusions extend from the opening of the isolation groove to the bottom of the groove, thereby increasing the area of ​​the isolation groove and reducing the polycrystalline silicon area of ​​the first doped region and / or the second doped region. This reduces the overall polycrystalline silicon coverage area on the back of the cell, lowers parasitic absorption of the polycrystalline silicon, and improves the optical performance of the cell. Simultaneously, the protrusions ensure that the one-dimensional horizontal distance between the first and second doped regions remains unchanged, thus guaranteeing that the distance at which electrons and holes separate and migrate to the N-type and P-type doped regions within the silicon substrate remains constant, ensuring the stability of the P-type and N-type doped regions. The doped region enhances carrier transport performance, ensuring the battery's electrical performance doesn't degrade. Furthermore, each protruding structure features a apex protrusion composed of multiple ridges on its surface. This apex protrusion, located near the isolation groove, effectively passivates the apex of the protruding structure with polysilicon from the first and / or second doped regions, maximizing carrier transport and collection and improving electrical performance. Simultaneously, the apex protrusion increases the passivation layer coverage area on the isolation groove sidewalls, ensuring the apex is fully and uniformly covered by the passivation film and reducing incident light reflectivity at the apex, thus enhancing both electrical and optical performance. Moreover, the multiple ridges prevent sharp corners, facilitating passivation film deposition and preventing stress concentration that could lead to film punctures and cracks. The ridge structure also facilitates multi-angle light trapping, fully utilizing incident light from various angles and further improving the battery's optical and electrical performance. Therefore, the back-contact solar cell provided in this disclosure can reduce the polycrystalline silicon coverage area on the entire back of the cell, reduce the parasitic absorption of polycrystalline silicon, improve the optical performance of the cell while ensuring the electrical performance, and at the same time increase the coverage area of ​​the passivation layer, improve the carrier transport and collection function, thereby improving the optical and electrical performance of the cell.

[0012] In one alternative embodiment, the back-contact solar cell further includes:

[0013] The passivation layer is located on the surface of the first doped region and the surface of the second doped region, and covers the sidewalls and bottom of the isolation groove.

[0014] In one alternative embodiment, the rib extends from the opening of the isolation groove to the bottom of the isolation groove;

[0015] Each protruding structure surface includes a vertex protrusion, and the number of ribs in each vertex protrusion is 2 to 10;

[0016] In each apex protruding structure, multiple ribs are arranged along a second direction.

[0017] Beneficial effects: The back-contact solar cell provided in this disclosure has ribs that extend from the opening of the isolation groove to the bottom of the isolation groove, so that the surface of the first doped region and / or the second doped region of the ribs extends all the way to the bottom of the groove. This allows polycrystalline silicon to effectively passivate the surface of the ribs corresponding to the bottom of the isolation groove, thereby more fully realizing the carrier transport and collection functions. At the same time, it can further increase the coverage area of ​​the passivation layer on the sidewall of the isolation groove, further improve the performance of the cell, and reduce the incident light reflectivity at the apex position, thereby improving the electrical and optical performance of the cell.

[0018] In one alternative implementation, each protrusion structure further includes:

[0019] The smooth parts located on both sides of the apex protruding structure extend from the opening of the isolation groove to the bottom of the isolation groove;

[0020] The passivation layer covers the surface of multiple ridges of the apex protruding structure and the surface of the smooth portion.

[0021] Beneficial effects: The back-contact solar cell provided in this disclosure has a light-surface portion on both sides of the top corner protrusion of each protrusion structure, and the light-surface portion extends from the opening of the isolation groove to the bottom of the isolation groove, which can improve the uniformity of passivation of the sidewall of the isolation groove, improve the reliability and passivation performance of the passivation layer, thereby improving the electrical and optical performance of the cell.

[0022] In one optional embodiment, the width of the protrusion structure along the first direction is 1 to 20 μm;

[0023] The width of the protrusion along the second direction is 1–50 μm.

[0024] In one alternative embodiment, the ribs of the apex protruding structure extend from the opening of the isolation groove to the bottom of the isolation groove;

[0025] The width of the rib along the first direction is 1–10 μm;

[0026] The width of the rib along the second direction is 1 to 10 μm.

[0027] In one alternative embodiment, the protrusion structure includes a first protrusion structure and a second protrusion structure;

[0028] The sidewall of the isolation groove near the first doped region includes a plurality of first protrusions arranged along the second direction;

[0029] The sidewall of the isolation groove near the second doped region includes a plurality of second protrusion structures arranged along the second direction.

[0030] Beneficial effects: The back-contact solar cell provided in this disclosure has a first protrusion structure and a second protrusion structure respectively provided on the two sidewalls of the isolation groove, which can further increase the area of ​​the isolation groove and reduce the polycrystalline silicon area of ​​the first doped region and the second doped region, thereby further reducing the polycrystalline silicon coverage area on the back of the entire cell; at the same time, the protruding structures at the top corners of the first protrusion structure and the second protrusion structure can increase the coverage area of ​​the passivation layer on the sidewall of the isolation groove, reduce the incident light reflectivity at the top corner position, and further improve the electrical and optical performance of the cell.

[0031] In one alternative embodiment, at least a portion of the apex protrusions of the first protrusion structure and the apex protrusions of the second protrusion structure are correspondingly arranged on both sides of the isolation groove.

[0032] In one optional embodiment, the first protrusion structure on each side of the isolation groove corresponds one-to-one with the second protrusion structure;

[0033] The apex protrusion of each first protrusion structure is set to correspond to the apex protrusion of the second protrusion structure.

[0034] Beneficial effects: The back-contact solar cell provided in this disclosure, by setting a one-to-one correspondence between the first protrusion structure and the second protrusion structure on both sides of the isolation groove; and by setting the apex protrusion structure of each first protrusion structure to correspond with the apex protrusion structure of the second protrusion structure, can make the straight-line distance between the apex protrusion structures of the first and second protrusion structures relatively short. This ensures that the one-dimensional distance between the first and second doped regions remains unchanged while reducing the polycrystalline silicon coverage area on the back side. It can also ensure that the distance for electrons and holes inside the silicon substrate to separate and move to the N-type and P-type doped regions remains unchanged, thereby improving the carrier transport performance of the P-type and N-type doped regions and giving the cell higher electrical and optical performance.

[0035] In one alternative embodiment, the sidewalls of the isolation groove are sloped relative to the backlight surface;

[0036] or:

[0037] The sidewalls of the isolation groove are perpendicular to the backlight surface. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the specific embodiments of this disclosure or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0039] Figure 1 This is a top view schematic diagram of the structure of a back-contact solar cell in the prior art.

[0040] Figure 2 This is a top view schematic diagram of the structure of a back-contact solar cell according to an embodiment of the present disclosure.

[0041] Figure 3 This is a top view schematic diagram of the protruding structure on the sidewall of the isolation groove in the back contact solar cell of this disclosure embodiment.

[0042] Figure 4A This is a schematic diagram showing the distribution of the first and second protrusion structures on the sidewall of the isolation groove in a back-contact solar cell according to an embodiment of this disclosure.

[0043] Figure 4B This is a schematic diagram showing the distribution of the first and second protrusion structures on the sidewall of the isolation groove in another embodiment of the present disclosure solar cell.

[0044] Figure 5 This is a schematic diagram of the structure in a back-contact solar cell of this disclosure, where the sidewall of the isolation groove is sloped relative to the backlight surface.

[0045] Figure 6 This is a schematic diagram of the structure of the back contact solar cell in this disclosure, where the sidewall of the isolation groove is perpendicular to the backlight surface. Figure 7 This is a schematic diagram of the passivation layer in a back-contact solar cell according to an embodiment of this disclosure.

[0046] Figure 8 This is a top-view scanning electron microscope schematic diagram of the sidewall morphology of the isolation groove near the first doped region of the back contact solar cell according to an embodiment of the present disclosure.

[0047] Figure 9 This is a 45° cross-sectional scanning electron microscope schematic diagram of the sidewall morphology of the isolation groove near the first doped region of the back contact solar cell according to an embodiment of the present disclosure.

[0048] Explanation of reference numerals in the attached figures:

[0049] 1. P-type doped region; 2. N-type doped region; 3. Isolation region; 10. Substrate layer; 20. First doped region; 30. Second doped region; 40. Isolation groove; 41. Textured structure; 50. Raised structure; 51. Corner protrusion structure; 511. Rib; 52. Smooth surface portion; 60. Passivation layer; 501. First raised structure; 502. Second raised structure. Detailed Implementation

[0050] The present disclosure will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the present disclosure and not intended to limit it. It should also be noted that, for ease of description, only the parts relevant to the present disclosure are shown in the drawings, not all structures. In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts of the present disclosure. The accompanying drawings show various structural schematic diagrams according to embodiments of the present disclosure. These drawings are not drawn to scale, and some details are enlarged for clarity and may be omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed. In the context of this disclosure, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intermediate layer / element between them. Additionally, if one layer / component is "above" another layer / component in one orientation, then when the orientation is reversed, that layer / component can be "below" that other layer / component.

[0051] Back-contact batteries, by moving the front grid lines to the back, not only avoid light loss due to front grid lines and improve optical performance, but also offer better aesthetics, making them particularly suitable for high-end distributed applications. In existing technologies, such as... Figure 1 As shown, the sidewalls of isolation region 3 are planar, resulting in a large polysilicon area on the surfaces of P-type doped region 1 and N-type doped region 2. Currently, parasitic absorption of polysilicon is a key factor affecting the improvement of optical performance in back-contact batteries. Reducing the thickness and coverage area of ​​polysilicon is crucial for reducing parasitic absorption and improving battery optical performance, and is also an important measure for further efficiency improvement. Expanding the width of the isolation region is an effective way to reduce the polysilicon coverage area on the back surface. However, directly expanding the width of the isolation region can lead to two problems: firstly, it increases the distance electrons and holes inside the silicon substrate travel to the N-type and P-type doped regions, resulting in poorer carrier transport performance; secondly, it makes the p / n-poly area too small, reducing the collection area for internal carriers and severely degrading the battery's electrical performance.

[0052] Therefore, a solution is needed to reduce parasitic absorption in polycrystalline silicon while ensuring the carrier transport performance of the P-type and N-type doped regions, thereby improving the optical performance of the battery while also taking into account its electrical performance.

[0053] refer to Figure 2 and Figure 3 This embodiment provides a back-contact solar cell, including: a substrate layer 10, including a light-receiving surface and a back-lighting surface disposed opposite to each other;

[0054] The first doped region 20 and the second doped region 30 are alternately disposed on the back side of the substrate layer 10 along the first direction; both the first doped region 20 and the second doped region 30 extend along the second direction.

[0055] The isolation groove 40 occupies the space between adjacent first doped regions 20 and second doped regions 30 and extends into the substrate layer 10; the isolation groove 40 separates adjacent first doped regions 20 and second doped regions 30.

[0056] At least one sidewall of the isolation groove 40 includes a plurality of protrusions 50 arranged along a second direction; the protrusions 50 extend from the opening of the isolation groove 40 to the bottom of the isolation groove 40.

[0057] Each protruding structure 50 has a apex protruding structure 51 formed by multiple ribs 511 on its surface; the apex protruding structure 51 is located on the side of the protruding structure 50 near the isolation groove 40.

[0058] In some alternative embodiments, the first doped region 20 includes a first doped layer, and the second doped region 30 includes a second doped layer, wherein the material of the first doped layer and / or the second doped layer is polycrystalline silicon. The first doped layer is located on the side surface of the first doped region 20 facing away from the substrate layer 10; the second doped layer is located on the side surface of the second doped region 30 facing away from the substrate layer 10. The first direction is perpendicular to the second direction.

[0059] In some alternative embodiments, the first doped region 20 and the second doped region 30 respectively include structural layers diffused on the back side of the substrate layer 10.

[0060] Specifically, the substrate 10 is a silicon substrate. The doping type of the first doped region 20 is the same as that of the first doped layer, and the doping type of the second doped region 30 is the same as that of the second doped layer. The doping types of the first doped region 20 and the second doped region 30 are opposite. The doping type of the first doped region 20 is the same as or opposite to that of the substrate 10. In some embodiments, the first doped region 20 is a P-type doped region, and the second doped region 30 is an N-type doped region. In other embodiments, the first doped region 20 is an N-type doped region, and the second doped region 30 is a P-type doped region. The isolation groove 40 includes two sidewalls, one sidewall being located near the first doped region 20 and the other sidewall being located near the second doped region 30. The isolation groove 40 can be a trench structure relatively recessed into the surfaces of the first doped region 20 and the second doped region 30, obtained by laser etching and wet cleaning. In this embodiment, the isolation trench extends a certain distance into the substrate 10, and the bottom of the isolation groove 40 is a textured structure 41. In some examples, the textured structure 41 is a pyramid textured surface.

[0061] Beneficial effects: The back-contact solar cell provided by this disclosure, on the one hand, includes at least one sidewall of the isolation groove comprising a plurality of protrusions arranged along a second direction. These protrusions extend from the opening of the isolation groove to the bottom of the groove, thereby increasing the area of ​​the isolation groove and reducing the polycrystalline silicon area of ​​the first doped region and / or the second doped region. This reduces the overall polycrystalline silicon coverage area on the back of the cell, lowers parasitic absorption of the polycrystalline silicon, and improves the optical performance of the cell. Simultaneously, the protrusions ensure that the one-dimensional horizontal distance between the first and second doped regions remains unchanged, thus guaranteeing that the distance at which electrons and holes separate and migrate to the N-type and P-type doped regions within the silicon substrate remains constant, ensuring the stability of the P-type and N-type doped regions. The doped region enhances carrier transport performance, ensuring the battery's electrical performance doesn't degrade. Furthermore, each protruding structure features a apex protrusion composed of multiple ridges on its surface. This apex protrusion, located near the isolation groove, effectively passivates the apex of the protruding structure with polysilicon from the first and / or second doped regions, maximizing carrier transport and collection and improving electrical performance. Simultaneously, the apex protrusion increases the passivation layer coverage area on the isolation groove sidewalls, ensuring the apex is fully and uniformly covered by the passivation film and reducing incident light reflectivity at the apex, thus enhancing both electrical and optical performance. Moreover, the multiple ridges prevent sharp structures at the apex, facilitating passivation film deposition and preventing stress concentration that could lead to film punctures and cracks. The ridges also facilitate multi-angle light trapping, fully utilizing incident light from various angles and further improving the battery's optical and electrical performance. Therefore, the back-contact solar cell provided in this disclosure can reduce the polycrystalline silicon coverage area on the entire back of the cell, reduce the parasitic absorption of polycrystalline silicon, improve the optical performance of the cell while ensuring the electrical performance, and at the same time increase the coverage area of ​​the passivation layer, improve the carrier transport and collection function, thereby improving the optical and electrical performance of the cell.

[0062] Figure 8 , Figure 9 The following are electron microscope schematic diagrams of the sidewalls of the isolation groove 40 near the first doped region 20, taken from different directions. It can be seen that the sidewalls include multiple protrusions 50, and the top of each protrusion 50 includes a apex protrusion 51 composed of multiple ribs 511.

[0063] For ease of explanation, Figure 3The following description uses the sidewall of the isolation groove 40 near the first doped region 20 as an example. In practice, the sidewall of the isolation groove 40 near the second doped region 30 may also include multiple protruding structures 50, each protruding structure 50 having a apex protruding structure 51 formed by multiple ribs 511 at its top. The first doped region 20 and the second doped region 30 are alternately arranged in the first direction. Figures 5-7 All are cross-sectional views parallel to the first direction and perpendicular to the backlight surface.

[0064] In some alternative implementations, such as Figure 7 As shown, the back-contact solar cell also includes:

[0065] The passivation layer 60 is located on the surface of the first doped region 20 and the surface of the second doped region 30, and covers the sidewalls and bottom of the isolation groove 40.

[0066] In some alternative embodiments, the rib 511 extends from the opening of the isolation groove 40 to the bottom of the isolation groove 40;

[0067] Each protrusion structure 50 surface includes a apex protrusion structure 51, and the number of ribs 511 in each apex protrusion structure 51 is 2 to 10;

[0068] In each apex protruding structure 51, multiple ribs 511 are arranged along a second direction.

[0069] Beneficial effects: The back-contact solar cell provided in this disclosure has ribs that extend from the opening of the isolation groove to the bottom of the isolation groove, so that the surface of the first doped region and / or the second doped region of the ribs extends all the way to the bottom of the groove. This allows polycrystalline silicon to effectively passivate the surface of the ribs corresponding to the bottom of the isolation groove, thereby more fully realizing the carrier transport and collection functions. At the same time, it can further increase the coverage area of ​​the passivation layer on the sidewall of the isolation groove, further improve the performance of the cell, and reduce the incident light reflectivity at the apex position, thereby improving the electrical and optical performance of the cell.

[0070] In some alternative implementations, each protrusion structure 50 further includes:

[0071] The smooth portion 52 is located on both sides of the top corner protrusion structure 51, and the smooth portion 52 extends from the opening of the isolation groove 40 to the bottom of the isolation groove 40;

[0072] The passivation layer 60 covers the surface of the multiple ribs 511 of the apex protruding structure 51 and the surface of the smooth portion 52.

[0073] Beneficial effects: The back-contact solar cell provided in this disclosure has a light-surface portion on both sides of the top corner protrusion of each protrusion structure, and the light-surface portion extends from the opening of the isolation groove to the bottom of the isolation groove, which can improve the uniformity of passivation of the sidewall of the isolation groove, improve the reliability and passivation performance of the passivation layer, thereby improving the electrical and optical performance of the cell.

[0074] In some alternative embodiments, the width of the protrusion structure 50 along the first direction is 1 to 20 μm;

[0075] The width of the protrusion 50 along the second direction is 1 to 50 μm.

[0076] In some alternative embodiments, the ribs 511 of the apex protrusion 51 extend from the opening of the isolation groove 40 to the bottom of the isolation groove 40;

[0077] The width of the rib 511 along the first direction is 1 to 10 μm;

[0078] The width of the rib 511 along the second direction is 1 to 10 μm.

[0079] In some alternative embodiments, the protrusion structure 50 includes a first protrusion structure 501 and a second protrusion structure 502;

[0080] The sidewall of the isolation groove 40 near the first doped region 20 includes a plurality of first protrusion structures 501 arranged along the second direction;

[0081] The sidewall of the isolation groove 40 near the second doped region 30 includes a plurality of second protrusion structures 502 arranged along the second direction.

[0082] Beneficial effects: The back-contact solar cell provided in this disclosure has a first protrusion structure and a second protrusion structure respectively provided on the two sidewalls of the isolation groove, which can further increase the area of ​​the isolation groove and reduce the polycrystalline silicon area of ​​the first doped region and the second doped region, thereby further reducing the polycrystalline silicon coverage area on the back of the entire cell; at the same time, the protruding structures at the top corners of the first protrusion structure and the second protrusion structure can increase the coverage area of ​​the passivation layer on the sidewall of the isolation groove, reduce the incident light reflectivity at the top corner position, and further improve the electrical and optical performance of the cell.

[0083] In some alternative embodiments, at least a portion of the apex protrusions 51 of the first protrusion structure 501 and the apex protrusions 51 of the second protrusion structure 502 are correspondingly arranged on both sides of the isolation groove 40.

[0084] In specific implementation, such as Figure 4AAs shown, "corresponding setting" means that the projection of the apex protrusion 51 of the first protrusion structure 501 onto the AA surface overlaps with the projection of the apex protrusion 51 of the second protrusion structure 502 onto the AA surface. Here, the AA surface is a plane that is perpendicular to the backlight surface of the substrate and parallel to the second direction.

[0085] In some alternative embodiments, at least a portion of the projection of the first protrusion 501 onto the AA surface overlaps with the projection of the second protrusion 502 onto the AA surface on both sides of the isolation groove 40.

[0086] In some alternative embodiments, the first protrusion structure 501 on both sides of the isolation groove 40 corresponds one-to-one with the second protrusion structure 502;

[0087] The apex protrusion structure 51 of each first protrusion structure 501 is provided in correspondence with the apex protrusion structure 51 of the second protrusion structure 502.

[0088] In specific implementation, "one-to-one correspondence" means that the projection of the apex protrusion 51 of each first protrusion structure 501 onto the AA surface overlaps with the projection of the apex protrusion 51 of a second protrusion structure 502 onto the AA surface.

[0089] Beneficial effects: The back-contact solar cell provided in this disclosure, by setting a one-to-one correspondence between the first protrusion structure and the second protrusion structure on both sides of the isolation groove; and by setting the apex protrusion structure of each first protrusion structure to correspond with the apex protrusion structure of the second protrusion structure, can make the straight-line distance between the apex protrusion structures of the first and second protrusion structures relatively short. This ensures that the one-dimensional distance between the first and second doped regions remains unchanged while reducing the polycrystalline silicon coverage area on the back side. It can also ensure that the distance for electrons and holes inside the silicon substrate to separate and move to the N-type and P-type doped regions remains unchanged, thereby improving the carrier transport performance of the P-type and N-type doped regions and giving the cell higher electrical and optical performance.

[0090] In some alternative embodiments, at least a portion of the apex protrusions 51 of the first protrusion structure 501 and the apex protrusions 51 of the second protrusion structure 502 are staggered on both sides of the isolation groove 40, such as... Figure 4B As shown.

[0091] In specific implementation, "interlaced setting" means that at least part of the projection of the apex protrusion 51 of the first protrusion structure 501 onto the AA surface does not overlap with the projection of the apex protrusion 51 of the second protrusion structure 502 onto the AA surface.

[0092] In some alternative implementations, the projection of the apex protrusion 51 of each first protrusion 501 onto the AA surface overlaps the projection of the boundary line M of the two adjacent second protrusions 502 located on the other side of the isolation groove onto the AA surface.

[0093] Specifically, such as Figure 4B As shown, the apex protrusion 51 of a first protrusion structure 501 is located on the BB surface, and the boundary line M of two adjacent second protrusion structures 502 on the other side of the isolation groove is also located on the BB surface. The BB surface is a plane perpendicular to the backlight surface of the substrate and parallel to the first direction.

[0094] In some alternative embodiments, the sidewalls of the isolation groove 40 are sloped relative to the backlight surface, such as... Figure 5 As shown;

[0095] or:

[0096] The sidewall of the isolation groove 40 is perpendicular to the backlight surface, such as... Figure 6 As shown.

[0097] In some alternative embodiments, the sidewall of the isolation groove 40 is inclined relative to the backlight surface, and a cross-sectional view of the sidewall of the isolation groove 40 is shown below. Figure 5 As shown, the top view of the sidewall of the isolation groove 40 is as follows. Figure 3 As shown.

[0098] In some optional embodiments, the first doped region 20 includes: a first tunneling oxide layer and a first doped layer stacked sequentially, the first tunneling oxide layer being relatively close to the backlight surface; the first doped layer being located on the upper surface of the first doped region 20;

[0099] The second doped region 30 includes: a second tunneling oxide layer and a second doped layer stacked sequentially, the second tunneling oxide layer being relatively close to the backlight surface; the second doped layer being located on the upper surface of the second doped region 30; the conductivity type of the second doped layer being opposite to that of the first doped layer.

[0100] The material of the first doped layer and / or the second doped layer is polycrystalline silicon.

[0101] In some alternative embodiments, the first doped region 20 further includes a first inner extension layer located between the substrate layer 10 and the first tunneling oxide layer, the first inner extension layer having the same conductivity type as the first doped layer;

[0102] The second doped region 30 also includes a second inner extension layer located between the substrate layer 10 and the second tunneling oxide layer, the second inner extension layer having the same conductivity type as the second doped layer.

[0103] In the description of this specification, the references to terms such as "this embodiment," "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction. 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 indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0104] The above description does not provide detailed explanations of the technical aspects of each layer's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0105] The above description is merely a preferred embodiment and the technical principles employed in this disclosure. Those skilled in the art will understand that this disclosure is not limited to the specific embodiments described above, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of this disclosure. Therefore, although this disclosure has been described in detail through the above embodiments, it is not limited to the above embodiments. Many other equivalent embodiments may be included without departing from the concept of this disclosure, and the scope of protection of this disclosure is determined by the scope of the appended claims.

Claims

1. A back-contact solar cell, characterized in that, include: The base layer includes a light-receiving surface and a backlighting surface that are positioned opposite to each other; A first doped region and a second doped region are alternately disposed on one side of the back surface of the substrate layer along a first direction; both the first doped region and the second doped region extend along a second direction. An isolation groove occupies the space between adjacent first and second doped regions and extends into the substrate layer; The isolation groove separates the adjacent first doped region and the second doped region; At least one sidewall of the isolation groove includes a plurality of protrusions arranged along a second direction; the protrusions extend from the opening of the isolation groove to the bottom of the isolation groove; Each of the protruding structures has a apex protrusion structure composed of multiple ridges on its surface; the apex protrusion structure is located on the side of the protruding structure closest to the isolation groove.

2. The back-contact solar cell according to claim 1, characterized in that, The back-contact solar cell also includes: A passivation layer is located on the surfaces of the first doped region and the second doped region, and covers the sidewalls and bottom of the isolation groove.

3. The back-contact solar cell according to claim 1, characterized in that, Also includes: The rib extends from the opening of the isolation groove to the bottom of the isolation groove; Each of the protruding structures includes a apex protrusion, and in each apex protrusion, the number of ribs is 2 to 10; In each of the aforementioned apex protrusions, a plurality of the aforementioned ribs are arranged along a second direction.

4. The back-contact solar cell according to claim 2, characterized in that, Each of the aforementioned protrusion structures further includes: The smooth surface portions located on both sides of the apex protruding structure extend from the opening of the isolation groove to the bottom of the isolation groove; The passivation layer covers the surfaces of the multiple ridges of the apex protruding structure and the surface of the smooth portion.

5. The back-contact solar cell according to claim 1, characterized in that, The width of the protrusion structure along the first direction is 1 to 20 μm; The width of the protrusion structure along the second direction is 1 to 50 μm.

6. The back-contact solar cell according to claim 5, characterized in that, The ribs of the apex protruding structure extend from the opening of the isolation groove to the bottom of the isolation groove; The width of the rib along the first direction is 1 to 10 μm; The width of the rib along the second direction is 1 to 10 μm.

7. The back-contact solar cell according to claim 1, characterized in that, The protrusion structure includes a first protrusion structure and a second protrusion structure; The sidewall of the isolation groove near the first doped region includes a plurality of first protrusions arranged along the second direction; The sidewall of the isolation groove near the second doped region includes a plurality of second protrusion structures arranged along the second direction.

8. The back-contact solar cell according to claim 7, characterized in that, On both sides of the isolation groove, at least a portion of the apex protrusions of the first protrusion structure are correspondingly provided with the apex protrusions of the second protrusion structure.

9. The back-contact solar cell according to claim 8, characterized in that, The first protrusion structure on both sides of the isolation groove corresponds one-to-one with the second protrusion structure; The apex protrusion of each of the first protrusion structures is provided in correspondence with the apex protrusion of the second protrusion structure.

10. The back-contact solar cell according to claim 1, characterized in that, The sidewall of the isolation groove is inclined relative to the backlight surface; or: The sidewall of the isolation groove is perpendicular to the backlight surface.

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