Back contact solar cell and photovoltaic module

Abstract

The invention provides a back contact solar cell and a photovoltaic module, and relates to the technical field of photovoltaics. The back contact solar cell includes: a substrate; the N-type doped layer and the P-type doped layer are arranged on the first surface of the substrate at intervals; a first edge isolation region is arranged between the N-type doped layer and the side wall; a second edge isolation region is arranged between the P-type doped layer and the side wall; the first edge isolation region comprises a first segment which is adjacent to the side wall and comprises a first suede structure; and a second segment; the second edge isolation region comprises a third section which is adjacent to the side wall and a fourth section which is adjacent to the third section and is continuous with the third section; the third segment is inclined relative to the fourth segment, and each of the third segment and the fourth segment comprises a second suede structure. The edge isolation effect is improved, and entering of water vapor is reduced.

Description

Technical Field

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

[0002] Due to the structure without grid lines on the light-facing surface, the back-contact solar cell can make full use of sunlight, resulting in higher efficiency. Moreover, due to the structure without grid lines on the light-facing surface, the appearance of the module is more beautiful, so it has broad application prospects.

[0003] In the back-contact solar cell, two doping layers with opposite doping types are both arranged on the backlight surface of the substrate. Therefore, the back surface of the back-contact cell has a relatively complex structure, and there is a problem of insufficient edge isolation. Summary of the Invention

[0004] The present invention provides a back-contact solar cell and a photovoltaic module, aiming to solve the problem of insufficient edge isolation of the existing back-contact solar cell.

[0005] In the first aspect of the present invention, a back-contact solar cell is provided, including:

[0006] A substrate, along the thickness direction of the substrate, the substrate has opposite first surface, second surface, and side walls connecting the first surface and the second surface;

[0007] An N-type doping layer and a P-type doping layer, which are arranged at intervals on the first surface;

[0008] Between the N-type doping layer and the side wall, there is a first edge isolation region;

[0009] Between the P-type doping layer and the side wall, there is a second edge isolation region;

[0010] The first edge isolation region includes: a first segment, the first segment is adjacent to the side wall, the surface of the first segment has an inclined surface relative to the substrate surface where the N-type doping layer is located, and includes a first texture structure; and a second segment that is farther from the side wall than the first segment, the surface of the second segment is substantially parallel to the substrate surface where the N-type doping layer is located;

[0011] The second edge isolation region includes: a third segment, the third segment is adjacent to the side wall, the surface of the third segment has an inclined surface relative to the substrate surface where the P-type doping layer is located; and a fourth segment, the fourth segment is adjacent to and continuous with the third segment; the third segment is inclined relative to the fourth segment, and both the third segment and the fourth segment include a second texture structure.

[0012] In this application, by providing a first edge isolation region between the N-type doped layer and the sidewall, and a second edge isolation region between the P-type doped layer and the sidewall, the isolation effect can be enhanced. For the second texture structure on the first surface, the interfacial distance from the sidewall to the P-type doped layer is longer, which can increase the interfacial path length for water vapor or other undesirable elements to enter the back-contact solar cell, reduce the entry of water vapor or other undesirable elements, and thus prevent water vapor or other undesirable elements from affecting the passivation contact performance. At the same time, the film-forming quality of the passivation and antireflection layer in the N region is improved. In particular, there is a certain height difference between the surface of the N-type doped layer and the surface of the substrate itself, further strengthening the edge isolation effect.

[0013] Optionally, the surface of the second segment is a polished structure with a substantially flat surface.

[0014] Optionally, the back-contact solar cell further includes a passivation and antireflection layer that covers the P-type doped layer, the N-type doped layer, the first surface of the substrate, the second surface, and the sidewall.

[0015] Optionally, an interfacial passivation layer is included between the N-type doped layer and the substrate, and between the P-type doped layer and the substrate.

[0016] Optionally, the first edge isolation region further includes: a fifth segment located between the first segment and the second segment, and the fifth segment has a sidewall that is inclined with respect to the surfaces of the second segment and the first segment.

[0017] Optionally, the lateral width of the first segment is from 1 μm to 45 μm, the lateral width of the second segment is from 0.2 μm to 8 μm, and the lateral width of the fifth segment is from 0.5 μm to 10 μm.

[0018] Optionally, the second edge isolation region further includes: a sixth segment located between the fourth segment and the P-type doped layer.

[0019] Optionally, the lateral width of the third segment is from 5 μm to 50 μm, the lateral width of the fourth segment is from 5 μm to 250 μm, and the lateral width of the sixth segment is from 0.5 μm to 10 μm.

[0020] Optionally, the lateral width of the first edge isolation region is from 2 μm to 50 μm, and the lateral width of the second edge isolation is from 20 μm to 300 μm; or,

[0021] The lateral width of the second edge isolation region is greater than the width of the first edge isolation region.

[0022] Optionally, the morphology of the first suede structure is different from that of the second suede structure on the third segment.

[0023] Optionally, the first suede structure includes: a plurality of first-type pyramid structures; the second suede structure on the third segment includes: a plurality of second-type pyramid structures;

[0024] The distribution density of the first-type pyramid structures is less than that of the second-type pyramid structures;

[0025] Or,

[0026] The average spacing between adjacent first-type pyramid structures is greater than the average spacing between adjacent second-type pyramid structures;

[0027] Or,

[0028] The apex angle of the first-type pyramid structures is greater than the apex angle of the second-type pyramid structures; or,

[0029] The aspect ratio of the first-type pyramid structures is less than the aspect ratio of the second-type pyramid structures.

[0030] Optionally, a third suede structure is provided on the second surface; the third suede structure includes: a plurality of third-type pyramid structures;

[0031] The apex angle of the second-type pyramid structures is greater than the apex angle of the third-type pyramid structures.

[0032] Optionally, the apex angle of the first-type pyramid structures is 70° to 100°, the apex angle of the second-type pyramid structures is 65° to 95°, and the apex angle of the third-type pyramid structures is 60° to 90°.

[0033] Optionally, in the orthographic projection of the substrate, the projected area of the first suede structure is less than the projected area of the second suede structure.

[0034] Optionally, the contour line of the first edge isolation region on the side wall includes a wavy segment.

[0035] Optionally, the first surface includes: a third isolation region located between adjacent N-type doped layers and P-type doped layers; a fourth suede structure is provided on the third isolation region, and the fourth suede structure includes: a plurality of fourth-type pyramid structures; the size of the fourth-type pyramid structures is larger than the size of the second-type pyramid structures. Optionally, the surface of the first segment and the surface of the second segment have a first included angle, and the side wall of the fifth segment and the surface of the second segment have a second included angle, and the first included angle is greater than the second included angle.

[0036] In a second aspect of the present invention, there is provided a method for manufacturing a back-contact solar cell, comprising:

[0037] providing a substrate, which has opposite first and second surfaces and sidewalls connecting the first and second surfaces in the thickness direction of the substrate;

[0038] forming a P-type doped layer on the first surface of the substrate and patterning it;

[0039] forming an N-type doped layer on the first surface of the substrate and patterning it;

[0040] When patterning the N-type doped layer and / or the P-type doped layer, a first edge isolation region located between the N-type doped layer and the sidewall and a second edge isolation region between the P-type doped layer and the sidewall are formed. The first edge isolation region includes: a first segment adjacent to the sidewall, the surface of the first segment having an inclined surface relative to the substrate surface where the N-type doped layer is located and including a first texture structure; and a second segment farther from the sidewall than the first segment, the surface of the second segment being substantially parallel to the substrate surface where the N-type doped layer is located. The second edge isolation region includes: a third segment adjacent to the sidewall, the surface of the third segment having an inclined surface relative to the substrate surface where the P-type doped layer is located; and a fourth segment adjacent to and continuous with the third segment. The third segment is inclined with respect to the fourth segment, and both the third segment and the fourth segment include a second texture structure.

[0041] In a third aspect of the present invention, there is provided a photovoltaic module, comprising: a plurality of any one of the foregoing back-contact solar cells.

[0042] The above-mentioned back-contact solar cell and photovoltaic module have the same or similar beneficial effects. To avoid repetition, they will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0044] Figure 1 and Figure 2 show partial structural schematic diagrams of two back-contact solar cells in the embodiments of the present invention;

[0045] Figures 3 to 9Shows partial SEM images of several back-contact solar cells in embodiments of the present invention.

[0046] Explanation of the drawing reference numbers:

[0047] 1 - Substrate, 11 - First surface, 12 - Second surface, 13 - Sidewall, 2 - N-type doped layer, 3 - P-type doped layer, 4 - First edge isolation region, 41 - First segment, 42 - Second segment, 43 - Fifth segment, 5 - Second edge isolation region, 51 - Third segment, 52 - Fourth segment, 53 - Sixth segment, 6 - Third isolation region, 7 - Interface passivation layer. Detailed implementation manners

[0048] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0049] The present invention provides a back-contact solar cell. Figure 1 And Figure 2 In [relevant figures], it is mainly used to illustrate the main structure of the back-contact solar cell, as well as the first edge isolation region and the second edge isolation region, and other parts are omitted. Figure 1 And Figure 2 The wavy lines in [relevant figures] indicate omissions. Refer to Figure 1 And Figure 2 This back-contact solar cell includes: a substrate 1, an N-type doped layer 2, and a P-type doped layer 3. An interface passivation layer 7, such as a tunneling oxide layer, is further included between the N-type doped layer 2 and the substrate 1, and between the P-type doped layer 3 and the substrate 1. The SEM image is a scanning electron microscope image. The material of the substrate 1 can be selected from materials such as silicon (Si), germanium (Ge), or gallium arsenide (GaAs). In terms of the conduction type, the substrate 1 can be an intrinsic conductive substrate, an N-type conductive substrate, or a P-type conductive substrate. For example, when the substrate 1 is an N-type conductive substrate, the N-type silicon substrate has advantages such as high minority carrier lifetime, no optical degradation, and good low-light performance.

[0050] Along the thickness direction Q of the substrate 1, the substrate 1 has opposite first surface 11, second surface 12, and sidewall 13 connecting the first surface 11 and the second surface 12. During the normal operation of the back-contact solar cell, the surface of the substrate 1 that mainly absorbs light is the second surface 12. The second surface 12 is the light-facing surface of the substrate 1, the first surface 11 is the backlight surface of the substrate 1, and the sidewall 13 connects the first surface 11 and the second surface 12. Here, the sidewall 13 refers to all or most of the sidewalls connecting the first surface 11 and the second surface 12.

[0051] The N-type doped layer 2 and the P-type doped layer 3 are arranged at intervals on the first surface 11, and the intervals here are used to avoid short circuits.

[0052] Refer to Figure 1 and Figure 2 , between the N-type doped layer 2 and the sidewall 13, there is a first edge isolation region 4, which means that between the N-type doped layer 2 adjacent to the sidewall 13 and the sidewall, there is a first edge isolation region 4. Between the P-type doped layer 3 and the sidewall 13, there is a second edge isolation region 5, which means that between the P-type doped layer 3 adjacent to the sidewall 13 and the sidewall 13, there is a second edge isolation region 5. This edge isolation region separates the boundary of the doped layers (the N-type doped layer 2 and the P-type doped layer 3) from the sidewall of the substrate 1.

[0053] Refer to Figure 1 , the first edge isolation region 4 includes a first segment 41 and a second segment 42. The first segment 41 is adjacent to the sidewall 13; the surface of the first segment 41 has an inclined surface relative to the substrate surface where the N-type doped layer 2 is located, that is, the surface of the first segment 41 has an inclined surface relative to the region corresponding to the N-type doped layer 2 in the first surface, and the surface of the first segment 41 has a first matte structure; the surface of the second segment 42 is substantially parallel to the substrate surface where the N-type doped layer is located, that is to say, the surface of the second segment 42 is substantially parallel to the region corresponding to the N-type doped layer 2 in the first surface.

[0054] Refer to Figure 1 and Figure 2 , the second edge isolation region 5 includes: a third segment 51 and a fourth segment 52. The third segment 51 is adjacent to the sidewall 13, and the surface of the third segment 51 has an inclined surface relative to the substrate surface where the P-type doped layer 3 is located, that is, the surface of the third segment 51 has an inclined surface relative to the region corresponding to the P-type doped layer 3 in the first surface; the third segment 51 is inclined relative to the fourth segment 52, and the fourth segment 52 is adjacent to the third segment 51 and is continuous with the third segment 51; Refer to Figure 3 , both the third segment 51 and the fourth segment 52 include a second matte structure.

[0055] In the above structure, when an N-type substrate is adopted, the region where the P-type doping layer 3 is located is the junction region of the battery, which has the opposite conductivity type to the substrate. At the same time, after the battery is made into a module, the front and back surfaces of the back-contact solar cell are protected by multiple-layer structures. Water vapor or other undesirable elements in the environment are more likely to penetrate from the side walls of the back-contact solar cell. Moreover, the interface passivation layer between the doping layer and the substrate 1 often easily adsorbs water vapor, etc., thereby affecting the interface passivation layer and destroying the passivation contact function between the doping layer and the substrate 1. And the P-type doping layer 3 is the junction region, which has a great influence on the efficiency of the battery. In the present application, both the third segment 51 and the fourth segment 52 have a second matte structure. Since the substrate close to the P-type doping layer 3 is set as a matte structure, when water vapor or other undesirable elements penetrate into the back-contact solar cell from the side walls of the back-contact solar cell, the water vapor tends to penetrate at the interfaces of each layer. Therefore, the matte structure increases the interface creepage distance and also increases the insulation, thereby better preventing the erosion of water vapor or other elements. Further, the N-type doping layer 2 has the same conductivity type as the substrate 1, forming a field region. The tolerance for damage to the interface passivation layer between the N-type doping layer 2 and the substrate 1 is higher than that of the P region. On this basis, in order to improve the film-forming quality of the passivation and antireflection layer, especially since there is a certain height difference between the surface of the N-type doping layer 2 and the surface of the substrate itself, the deposition quality of the passivation and antireflection layer is affected. Therefore, the second segment 42 adjacent to the N-type doping layer 2 is generally a polished structure, or the surface roughness of the second segment 42 is less than that of the first matte structure of the first segment 41, which can improve the overall film-forming quality of the passivation and antireflection layer and improve the passivation and antireflection effect.

[0056] In some embodiments, the surface of the first segment 41 has an inclined surface relative to the surface of the substrate where the N-type doping layer is located. Compared with a flat surface, the inclined surface makes the distance between the side of the first segment 41 far from the side wall 13 and the side wall 13 larger, enhancing the surface creepage distance and increasing the interface distance for water vapor to enter. It should be noted that the surface of the first segment 41 having an inclined surface relative to the surface of the substrate where the N-type doping layer is located mainly means that the surface of the first segment 41 has a certain angle relative to the surface of the substrate where the N-type doping layer is located. The surface of the first segment 41 may include a flat surface or a curved surface, etc. That is, the surface of the first segment 41 and the surface of the substrate where the N-type doping layer is located are not parallel. The inclined trend of the first segment 41 is generally: along the thickness direction Q of the substrate 1, the end of the surface of the first segment 41 close to the side wall 13 is farther from the surface of the substrate where the N-type doping layer is located than other positions of the surface of the first segment 41.

[0057] Refer to Figure 1 and Figure 2, compared with the first segment 41, the second segment 42 is farther away from the sidewall 13. The second segment 42 is adjacent to the N-type doped layer 2, and its surface is generally parallel to the substrate surface where the N-type doped layer is located, which is conducive to obtaining an N-type doped layer 2 with better film quality and the passivation and antireflection film layer thereon, improving the quality and effect of passivation and antireflection.

[0058] In some embodiments, the surface of the third segment 51 having an inclined surface relative to the substrate surface where the P-type doped layer is located mainly means that, relative to the substrate surface where the P-type doped layer is located, the surface of the third segment 51 has a certain angle. The surface of the third segment 51 may include a flat surface or a curved surface, etc., that is, the surface of the third segment 51 and the substrate surface where the P-type doped layer is located are not parallel. The inclination trend of the third segment 51 is generally: along the thickness direction Q of the substrate 1, one end of the surface of the third segment 51 close to the sidewall 13 may be farther away from the substrate surface where the P-type doped layer is located than other positions of the surface of the third segment 51. Here, the third segment 51 is inclined relative to the fourth segment 52, which means that the third segment 51 and the fourth segment 52 are not parallel. Whether the fourth segment 52 and the substrate surface where the P-type doped layer is located are parallel or not is not limited here. For example, they may be parallel to each other or not parallel.

[0059] Optionally, referring to Figure 1 and Figure 2 , the surface of the second segment 42 is a polished structure with a substantially flat surface. The surface of the second segment 42 is flatter, which is conducive to obtaining an N-type doped layer 2 with better film quality and the passivation and antireflection layer thereon, and can also ensure the quality and effect of passivation and antireflection in the adjacent area of the first surface 11 where the N-type doped layer 2 is provided.

[0060] Optionally, referring to Figure 2 , the first edge isolation region 4 further includes: a fifth segment 43 located between the first segment 41 and the second segment 42. The fifth segment 43 has a sidewall inclined relative to the surfaces of the second segment 42 and the first segment 41. The structure of the first edge isolation region 4 is more complex, increasing the creepage distance between the N-type doped layer 2 and the sidewall 13; the surface distance from the sidewall to the N-type doped layer is longer, which can increase the path length of water vapor entering, reduce the entry of water vapor, thereby preventing the influence of water vapor, and at the same time can also improve the light trapping effect. The fifth segment 43 having a sidewall inclined relative to the surfaces of the second segment 42 and the first segment 41 means that the sidewall of the fifth segment 43 is not parallel to both the second segment 42 and the first segment 41. Optionally, referring to Figure 2, the surface of the first segment 41 and the surface of the second segment 42 have a first included angle a, and the side wall of the fifth segment 43 and the surface of the second segment 42 have a second included angle b. The first included angle a is greater than the second included angle b. In contrast to b > a, in this application a > b. Then, the first segment 41, the fifth segment 43, and the second segment 42 are not arranged in a sequentially gentle manner, but have a large protrusion at the second segment 42 and the fifth segment 43, making the structure of the first edge isolation region 4 more complex, increasing the isolation effect between the N-type doping layer 2 and the side wall 13, as well as the water vapor isolation effect.

[0061] Optionally, the first included angle a here is 95° to 170°; the second included angle b here is 90° to 150°; the angle ranges of the above-mentioned included angles are easy to process and implement, and the protrusion is not too abrupt, avoiding hidden cracks, etc.

[0062] For example, the first included angle a here can be 95°, 100°, 105°, 110°, 120°, 125°, 130°, 140°, 145°, 150°, 160°, 170°. For another example, the second included angle b here can be 90°, 100°, 105°, 110°, 115°, 120°, 125°, 130°, 140°, 145°, 150°.

[0063] Optionally, the second edge isolation region 5 further includes a sixth segment 53. The sixth segment 53 is located between the fourth segment 52 and the P-type doping layer 3. The sixth segment 53 includes a side wall, and the sixth segment 53 has a side wall inclined with respect to the surface of the substrate 1 where the fourth segment 42 and the P-type doping layer 3 are located; this increases the creepage distance between the P-type doping layer 3 and the side wall 13; the surface distance from the side wall to the P-type doping layer 3 is longer, which can increase the path length of water vapor entering, reduce the entry of water vapor, thereby preventing the influence of water vapor, and at the same time can also improve the light trapping effect. The fact that the sixth segment 53 has a side wall inclined with respect to the surface of the substrate 1 where the fourth segment 42 and the P-type doping layer 3 are located means that the side wall of the sixth segment 53 is not parallel to the surface of the substrate 1 where the fourth segment 42 and the P-type doping layer 3 are located.

[0064] Optionally, the size of the sixth segment 53 in the thickness direction Q is 2 microns to 9 microns; the included angle between the sixth segment 53 and the fourth segment 52 is smaller than the included angle between the third segment 51 and the fourth segment 52. The above settings can increase or decrease the overall height difference of the second edge isolation region 5, increase the creepage distance and the isolation effect.

[0065] Optionally, the morphology of the first suede structure on the first edge isolation region 4 is different from that of the second suede structure on the third segment of the second edge isolation region. The difference in morphology here can refer to: the degree of protrusion, the degree of depression, the number of protrusions, the number of depressions, the distribution density of protrusions, the distribution density of depressions, etc. of the first suede structure, corresponding to those of the second suede structure on the third segment of the second edge isolation region.

[0066] Optionally, the first suede structure includes: a number of first-type pyramid structures, and the number of first-type pyramid structures in the first suede structure is not specifically limited; the second suede structure on the third segment includes: a number of second-type pyramid structures, and the number of second-type pyramid structures in the second suede structure on the third segment is not specifically limited; the distribution density of the first-type pyramid structures in the first suede structure is less than that of the second-type pyramid structures in the second suede structure on the third segment, that is, within the same area or unit area region, the number of first-type pyramid structures in the first suede structure is less than the number of second-type pyramid structures in the second suede structure on the third segment. The size of the same size or the size of the unit size here is not limited; it can be that the number of first-type pyramid structures in one or more same area or unit area regions of the first suede structure is less than the number of second-type pyramid structures in one or more same area or unit area regions of the second suede structure on the third segment. In the above solution, more consideration is given to effectively blocking the influence of water vapor or other undesirable elements on the edge of the P-type doping layer 3, while more consideration is given to the quality of the passivation antireflection layer on the edge of the N-type doping layer 2, thereby comprehensively improving the stability and efficiency of the battery cell.

[0067] For example, referring to Figure 3 , Figure 3 The second suede structure on the third segment 51 is outlined by a dotted line in the figure. The second-type pyramid structures of the second suede structure on the third segment 51 are densely and continuously distributed. For another example, Figure 4 is a partial SEM image of the second suede structure on the third segment 51, Figure 5 is a partial SEM image of the first suede structure, Figure 4 and Figure 5 are SEM images within the same area. The distribution density of the second-type pyramid structures in the second suede structure on the third segment 51 is greater than that of the first-type pyramid structures in the first suede structure.

[0068] Optionally, referring to Figure 4 and Figure 5, the undulation degree of the first suede structure is greater than that of the second suede structure on the third segment 51. In one case, it can be that the protrusion and / or depression degree of the first suede structure is greater than that of the second suede structure on the third segment 51; in another case, it can be that the protrusion and / or depression arrangement of the first suede structure is more disordered than that of the second suede structure on the third segment 51; in another case, it can be that the height of the protrusion and / or the depth of the depression of the first suede structure is greater than that of the second suede structure on the third segment 51.

[0069] Optionally, there is a gap between adjacent first-type pyramid structures in the first suede structure, or adjacent first-type pyramid structures are continuously distributed. For the case where adjacent first-type pyramid structures are continuously distributed, the gap between adjacent first-type pyramid structures is 0; optionally, there is a gap between adjacent second-type pyramid structures in the second suede structure on the third segment 51, or adjacent second-type pyramid structures are continuously distributed. For the case where adjacent second-type pyramid structures are continuously distributed, the gap between adjacent second-type pyramid structures is 0;

[0070] Optionally, referring to Figure 4 and Figure 5 , the average gap between adjacent first-type pyramid structures in the first suede structure is greater than the average gap between adjacent second-type pyramid structures in the second suede structure on the third segment 51. A larger average gap between adjacent first-type pyramid structures in the first suede structure is beneficial to the film-forming quality of the passivation antireflection layer. The average gap between such pyramid structures means: within a unit area or a specified area range, the average value of the gaps between various pyramids.

[0071] Optionally, the apex angle of the first-type pyramid structure is greater than that of the second-type pyramid structure. For a first-type pyramid structure, the apex angle of this type of pyramid structure is: for a pyramid structure, the included angle between two opposite side edges passing through the top of the tower. The top of the pyramid structure is the highest point in the pyramid. In the case where the highest part of the pyramid structure is a plane formed by multiple points of the same height, the tower here can be the geometric center of this plane. The apex angle of the first-type pyramid structure being greater than that of the second-type pyramid structure means: in the first suede structure, the apex angle of at least one first-type pyramid structure is greater than that of at least one second-type pyramid structure; or, the average value of the apex angles of multiple first-type pyramid structures in the first suede structure is greater than the average value of the apex angles of multiple second-type pyramid structures. A larger apex angle of the first-type pyramid structure is beneficial to the film-forming quality of the passivation antireflection film.

[0072] Optionally, the aspect ratio of the first type of pyramid structure is less than that of the second type of pyramid structure. The pyramid-like structure includes a bottom contour line opposite to the pyramid top, and the bottom contour line is the contour line of the pyramid-like structure closest to the substrate. The height of the pyramid-like structure refers to the distance between the pyramid top of the pyramid-like structure and the bottom contour line of the pyramid-like structure in the direction perpendicular to the plane where the bottom contour line is located. The width of the pyramid-like structure refers to the maximum dimension of the bottom contour line of the pyramid-like structure. The aspect ratio of the first type of pyramid structure refers to the ratio of the height of any first type of pyramid structure in the first textured surface to the width of the first type of pyramid structure, or the ratio of the average value of the heights of multiple first type of pyramid structures in the first textured surface to the average value of the widths of the multiple first type of pyramid structures; the determination method of the aspect ratio of the second type of pyramid structure is the same as that of the first type of pyramid structure, and for the sake of avoiding repetition, it will not be elaborated here. The second type of pyramid is taller and thinner, which is more conducive to increasing the surface creepage distance.

[0073] Figure 6 It is a partial SEM image of the second surface of the substrate 1. Optionally, referring to Figure 6 , the second surface of the substrate 1, that is, the light-facing surface of the substrate 1, has a third textured surface; the third textured surface includes a plurality of third type of pyramid structures, and the number of the third type of pyramid structures included in the third textured surface is not specifically limited. The determination method of the apex angle of the third type of pyramid structure is the same as that of the first type of pyramid structure described above. The apex angle of the second type of pyramid structure is greater than that of the third type of pyramid structure. Since the apex angle of the first type of pyramid structure is greater than that of the second type of pyramid structure, therefore, the apex angles of the first type of pyramid structure and the second type of pyramid structure are both greater than that of the third type of pyramid structure. The pyramid tops of the first type of pyramid structure and the second type of pyramid structure located on the backlight surface are relatively smooth, which is convenient for obtaining a film layer with better quality on the backlight surface, conducive to improving the passivation effect, etc., while the light-facing surface of the solar cell is more conducive to suppressing light reflection.

[0074] Optionally, the apex angle of the first type of pyramid structure is 70° to 100°, the apex angle of the second type of pyramid structure is 65° to 95°, and the apex angle of the third type of pyramid structure is 60° to 90°.

[0075] For example, the apex angles of the third type of pyramid structure can be 60°, 90°, 62°, 65°, 68°, 75°, 70°, 71°, 80°, 85°, 84°, 88°, 90°; for another example, the apex angles of the first type of pyramid structure can be 70°, 75°, 80°, 85°, 84°, 90°, 95°, 76.7°, 83.9°, 98.7, 100°; for another example, the apex angles of the second type of pyramid structure can be 65°, 70°, 75°, 80°, 85°, 90°, 88°, 95°, 77.8°, 86.3°, 91.7, 82.3°.

[0076] The orthographic projection of the matte surface structure on the first surface 11 refers to the projection of the matte surface structure on the first surface 11 when irradiated with light perpendicular to the first surface 11. Optionally, in the orthographic projection of the substrate, the projected area of the first matte surface structure is smaller than the projected area of the second matte surface structure. In the orthographic projection of the substrate, the projected area of the matte surface structure can refer to the area of the projection of the matte surface structure orthographically projected onto the first surface or the area of the projection of the matte surface structure orthographically projected onto the second surface. That is, the distribution range of the first matte surface structure is narrower than that of the second matte surface structure. The doping type of the substrate 1 is the same as that of the N-type doped layer structure and opposite to that of the P-type doped layer structure. Therefore, there is a risk of short circuit between the P-type doped layer and the substrate. The distribution range of the second matte surface structure is wider, further reducing the short circuit risk.

[0077] Figure 7 It is a view looking at the side wall along a direction perpendicular to the thickness direction Q of the substrate. Optionally, the contour line of the first edge isolation region on the side wall 13 includes a wavy section. The undulation degree of the contour line of the first edge isolation region on the side wall 13 is relatively large. The wavy section here can increase the surface area and the light absorption area, which is beneficial to improving the efficiency.

[0078] The first surface 11 includes: a third isolation region 6 located between adjacent N-type doped layer 2 and P-type doped layer 3. The third isolation region is used to prevent short circuit between adjacent N-type doped layer 2 and P-type doped layer 3.

[0079] Optionally, the third isolation region 6 has a fourth matte surface structure, and the fourth matte surface structure includes several fourth types of pyramid structures. The size of the fourth type of pyramid structure is larger than that of the second type of pyramid structure. The specific surface area of the fourth type of pyramid structure is larger, the isolation effect is more obvious, and the short circuit risk is lower.

[0080] Figure 8 It is a SEM image of the fourth type of pyramid structure at the position in the third isolation region 6 close to the N-type doped layer 2; Figure 9It is the SEM image of the fourth type of pyramid structure at the position near the P-type doping layer 3 in the third isolation region 6. The distribution density of the fourth type of pyramid structure at the position near the N-type doping layer 2 in the third isolation region 6 is less than or equal to the distribution density of the fourth type of pyramid structure at the position near the P-type doping layer in the third isolation region. That is to say, at the position near the N-type doping layer 2 in the third isolation region 6, within the same area or unit area region, the number of the fourth type of pyramid structure is less than or equal to the number of the fourth type of pyramid structure at the position near the P-type doping layer 3 in the third isolation region 6 within the same area or unit area region. Namely, at the position near the N-type doping layer 2 in the third isolation region 6, the fourth type of pyramid structure is more sparsely distributed, and at the position near the P-type doping layer 3 in the third isolation region 6, the fourth type of pyramid structure is more densely distributed within the same area or unit area region. The doping type of the substrate 1 is the same as that of the N-type doping layer structure and opposite to that of the P-type doping layer structure. Therefore, there is a risk of short circuit between the P-type doping layer and the substrate. At the position near the P-type doping layer in the third isolation region, the distribution density of the fourth type of pyramid structure is greater, further reducing the short circuit risk.

[0081] Optionally, referring to Figure 8 and Figure 9 , at the position near the N-type doping layer 2 in the third isolation region 6, the apex angle of the fourth type of pyramid structure is the first apex angle; at the position near the P-type doping layer 3 in the third isolation region 6, the apex angle of the fourth type of pyramid structure is the second apex angle; the ratio of the difference between the first apex angle and the second apex angle to the first apex angle or the second apex angle is less than or equal to 5%. That is to say, the first apex angle and the second apex angle are approximately equal with little difference, and the processes for forming the first apex angle and the second apex angle are compatible and the process is simpler. For example, both the first apex angle and the second apex angle are 70° to 80°.

[0082] Optionally, the second type of pyramid structure of the second surface texture on the fourth segment 52 is substantially the same as the fourth type of pyramid structure.

[0083] Optionally, referring to Figure 2, the lateral width d1 of the first edge isolation region 4 is 2 to 50 micrometers (μm). Exceeding 50 μm will cause a significant reduction in the collection efficiency of photo-generated carriers generated at the edge, while less than 2 μm will result in insufficient edge isolation distance of the N region, leading to insufficient protection of the N-type doped layer and the interface passivation layer. Therefore, setting the lateral width of the first edge isolation region 4 within the above range can improve the collection efficiency of photo-generated carriers and fully protect the N-type doped layer and the interface passivation layer. It should be noted that in this application, all the lateral widths mentioned are perpendicular to the direction of the thickness Q of the substrate 1 and parallel to the direction in which the N-type doped layer and the P-type doped layer are alternately arranged. Or rather, in this application, all the lateral widths mentioned refer to the vertical distance from the side wall of the cell to the inside of the cell in the vertical projection when looking down at the back of the solar cell.

[0084] For example, d1 can be 2μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm.

[0085] Optionally, the lateral width d2 of the second edge isolation region 5 is 20 to 300 micrometers. Since the second edge isolation region 5 is adjacent to the P-type doped layer for the isolation of the junction region, if the second edge isolation region is less than 20 μm, the isolation of the P region structure is insufficient and the protection is inadequate; while exceeding 300 μm will affect the junction area and the cell efficiency.

[0086] For example, d2 can be 20μm, 50μm, 100μm, 125μm, 150μm, 175μm, 200μm, 225μm, 250μm, 275μm, 300μm.

[0087] Optionally, the lateral width d2 of the second edge isolation region 5 is greater than the width d1 of the first edge isolation region 4. Further, the ratio of the lateral width of the second edge isolation region 5 to the lateral width of the first edge isolation region 4 is 3 - 50. To meet the different requirements of the P region and the N region for edge isolation and comprehensively ensure the efficiency of the cell and the stability of the module. For example, the ratio of the lateral width of the second edge isolation region 5 to the lateral width of the first edge isolation region 4 can be 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50.

[0088] Optionally, the lateral width d3 of the third isolation region 6 is 25 - 200 micrometers. Within this range, it can not only achieve effective isolation between the P region and the N region, but also ensure an effective junction area, which is beneficial to the performance of the solar cell. For example, d3 can be 20μm, 50μm, 100μm, 125μm, 150μm, 175μm, 200μm.

[0089] Optionally, the lateral width of the first segment 41 is 1 - 45 μm, the lateral width of the second segment 42 is 0.2 - 8 μm, and the lateral width of the fifth segment 43 is 0.5 - 10 μm. Within the above ranges, the edge isolation of the N region and the passivation and antireflection effects are considered comprehensively. For example, the lateral width of the first segment 41 can be 1μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, the lateral width of the second segment 42 can be 0.2μm, 0.5μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, and the lateral width of the fifth segment 43 can be 0.5μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 8.5μm, 9μm, 10μm.

[0090] Optionally, the lateral width d4 of the third segment 51 is 5 - 50 μm, the lateral width d5 of the fourth segment 52 is 5 - 250 μm; the lateral width d6 of the sixth segment 53 is 0.5 - 10 μm. Within the above ranges, the edge isolation of the P region and the passivation and antireflection effects are considered comprehensively. For example, the lateral width d4 of the third segment 51 can be 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, the lateral width d5 of the fourth segment 52 can be 5μm, 10μm, 50μm, 100μm, 150μm, 200μm, 250μm, and the lateral width d6 of the sixth segment 53 can be 0.5μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 8.5μm, 9μm, 10μm.

[0091] Optionally, the present application further includes a passivation and antireflection layer, and the passivation and antireflection layer covers the P-type doped layer 3, the N-type doped layer 2, and the first surface 11, the second surface 12, and the sidewall 13 of the substrate; optionally, the material of the passivation and antireflection layer can be one or more layers of superposition of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, silicon carbide, amorphous silicon, etc., to provide good passivation and antireflection effects.

[0092] Optionally, the present application further includes electrodes, including a first electrode in contact connection with the N-type doped layer 2, and a second electrode in contact connection with the P-type doped layer 3, to conduct current.

[0093] The present application also provides a method for manufacturing a back-contact solar cell, including the following steps.

[0094] Step 101, provide a substrate. Along the thickness direction of the substrate, the substrate has opposite first and second surfaces, and sidewalls connecting the first surface and the second surface.

[0095] Reference is made to the foregoing relevant descriptions. To avoid repetition, details are not elaborated herein.

[0096] Step 102: Form a P-type doped layer on the first surface of the substrate and pattern it; form an N-type doped layer on the first surface of the substrate and pattern it; when patterning the N-type doped layer and / or the P-type doped layer, form a first edge isolation region between the N-type doped layer and the sidewall, and a second edge isolation region between the P-type doped layer and the sidewall. The first edge isolation region includes: a first segment adjacent to the sidewall, the surface of the first segment having an inclined surface relative to the substrate surface where the N-type doped layer is located and including a first textured structure; and a second segment farther from the sidewall than the first segment, the surface of the second segment being substantially parallel to the substrate surface where the N-type doped layer is located. The second edge isolation region includes: a third segment adjacent to the sidewall, the surface of the third segment having an inclined surface relative to the substrate surface where the P-type doped layer is located; and a fourth segment adjacent to and continuous with the third segment. The third segment is inclined relative to the fourth segment, and both the third segment and the fourth segment include a second textured structure.

[0097] The method for preparing the back-contact solar cell may further include: forming a passivation and antireflection layer covering the N-type doped layer 2, the P-type doped layer 3, the first edge isolation region 4, and the second edge isolation region 5; forming a first electrode connected to the N-type doped layer 2 and a second electrode connected to the P-type doped layer 3.

[0098] Generally, the substrate 1 can be inserted into a carrier. The substrate 1 needs to be subjected to damage removal treatments such as polishing and cleaning. The processes for forming the N-type doped layer 2 and the P-type doped layer 3 on the substrate 1 can be plasma enhanced chemical vapor deposition (PECVD) process, hot wire chemical vapor deposition process, physical vapor deposition (PVD) process, low pressure chemical vapor deposition (LPCVD) process, or catalytic chemical vapor deposition process, etc. The patterning processes for the P-type doped layer and the N-type doped layer 2 can be laser etching process, ion milling etching process, plasma etching process, reactive ion etching process, alkali etching process, and acid etching process, etc.

[0099] In some embodiments, the formation methods of the N-type doped layer 2 and the P-type doped layer 3 are in-situ doping method or non-in-situ doping method. That is, the N-type doped layer 2 and the P-type doped layer 3 can be directly formed, or an intrinsic semiconductor layer can be formed first and then doped to form the N-type doped layer 2 and the P-type doped layer 3 respectively.

[0100] In some embodiments, the formation of the first edge isolation region 4 and the second edge isolation region can be achieved by combining an etching solution and a laser process. For example, to achieve a relatively uniform matte structure when forming the second edge isolation region 5, laser irradiation followed by cleaning with an etching solution can be used, and it can be adjusted by varying the laser energy, spot size, and the etching rate of the etching solution. When forming the first edge isolation region, local masking protection and a chain process for controlling liquid turnover can be used, providing a flexible implementation method.

[0101] It should be noted that when the etching solution or the polishing and cleaning solution in this application is an alkaline solution, a possible formulation of the alkaline solution can be: by volume ratio, 0.2% - 10% of NaOH (sodium hydroxide), 0.2% - 10% of an additive, and the remainder of the alkaline solution is mainly pure water.

[0102] In some embodiments, the width range of the first electrode and the second electrode is 5 μm to 100 μm. The processes for forming the first electrode and the second electrode can include electroplating, transfer printing processes (such as laser transfer printing, thermal transfer printing, etc.), screen printing, physical vapor deposition of metals or metal oxide electrodes, etc. Obviously, various processes can also be used in combination. For example, a seed layer can be printed first, and then the final first electrode and second electrode can be formed by electroplating on the seed layer; or metal oxide can be deposited by vapor deposition. For example, a transparent conductive oxide (TCO) can be used, and then the first electrode and the second electrode can be formed by screen printing or transfer printing.

[0103] In some embodiments, the process for forming the passivation and antireflection layer can be plasma enhanced chemical vapor deposition (PECVD) process, hot wire chemical vapor deposition process, physical vapor deposition (PVD) process, low pressure chemical vapor deposition (LPCVD) process, or catalysis, etc.

[0104] In some embodiments, the method for forming the first electrode and the second electrode may also be to coat the electrode paste on the passivation layer and then sinter it, so that the electrode paste penetrates through the passivation layer and forms electrical contacts with the N-type doped layer 2 and the P-type doped layer 3 respectively. When the back-contact solar cell has a passivation layer and the first electrode and the second electrode are local contact electrodes, the method for forming the first electrode and the second electrode may also be to first form a first opening and a second opening on the passivation layer, and then use methods such as printing paste, laser transfer printing, electroplating, electroless plating, photoinduced electroplating, or physical vapor deposition such as vacuum evaporation, magnetron sputtering, etc. to form the local contact first electrode and second electrode. The opening method may include laser film opening or using an etching paste that can react with the passivation layer to open the film. The method of making electrical contact through the opening can enable the back-contact solar cell to achieve lower recombination in the metal region and ensure the high conversion efficiency of the back-contact solar cell. Obviously, one or a combination of the above methods can also be used to form the first electrode and the second electrode. For example, the method of using a seed layer of physical vapor deposition (PVD) in combination with printing electrodes, or the method of screen printing electrode paste in combination with electroplating, or the combination of laser transfer printing method and screen printing sintering method, etc.

[0105] The present application may also provide a photovoltaic module, which may include several of any of the foregoing back-contact solar cells. The photovoltaic module may further include: encapsulation adhesive films located on the light-facing side and the backlight side of the back-contact solar cell, etc. The specific structure of the photovoltaic module is not limited.

[0106] The photovoltaic module may further include electrical connectors, and the electrical connectors here can play a role in conductive interconnection. For example, the electrical connectors may be solder tapes or conductive backplates, etc., and the electrical connectors are not specifically limited. The electrical connectors are electrically connected to the electrodes in at least two of the foregoing solar cells. Here, it may be that the electrical connectors are directly electrically connected to the foregoing electrodes or indirectly electrically connected, and neither is limited. The electrical connectors can electrically connect the first electrode in one of the two adjacent foregoing solar cells to the second electrode in the other solar cell to achieve conductive interconnection.

[0107] It should be noted that the relevant parts of the photovoltaic module, any of the foregoing back-contact solar cells, and the preparation method of the foregoing back-contact solar cells can be referred to each other and have the same or similar beneficial effects. To avoid repetition, they are not elaborated here.

[0108] It should be noted that in this article, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including that element.

[0109] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the purpose of the present invention and the scope protected by the claims. All of these are within the protection scope of the present invention.

Claims

1. A back contact solar cell, characterized in that: include: A substrate, wherein along a thickness direction of the substrate, the substrate has a first surface and a second surface opposite to each other, and a side wall connecting the first surface and the second surface; An N-type doped layer and a P-type doped layer are arranged on the first surface at intervals; A first edge isolation region is provided between the N-type doped layer and the sidewall; A second edge isolation region is provided between the P-type doped layer and the sidewall; The first edge isolation region comprises: a first segment, the first segment is adjacent to the side wall, the surface of the first segment has an inclined surface relative to the substrate surface where the N-type doped layer is located, and comprises a first velvet structure; and a second segment farther from the side wall than the first segment, the surface of the second segment is substantially parallel to the substrate surface where the N-type doped layer is located; The second edge isolation region includes: a third segment, the third segment is adjacent to the side wall, and the surface of the third segment has an inclined surface relative to the substrate surface where the P-type doped layer is located; and a fourth segment, the fourth segment is adjacent to the third segment and continuous with the third segment; the third segment is inclined relative to the fourth segment, and the third segment and the fourth segment both include a second velvet structure.

2. The back contact solar cell according to claim 1, characterized in that: The surface of the second segment is a substantially planar polished structure.

3. The back contact solar cell according to claim 1, characterized in that: It also includes a passivation anti-reflection layer, which covers the P-type doping layer, the N-type doping layer, the first surface of the substrate, the second surface and the side wall.

4. The back contact solar cell according to claim 1, characterized in that: An interface passivation layer is provided between the N-type doping layer and the substrate, and between the P-type doping layer and the substrate.

5. The back contact solar cell according to claim 1, characterized in that: The first edge isolation region further includes a fifth segment located between the first segment and the second segment, the fifth segment having a sidewall inclined relative to surfaces of the second segment and the first segment.

6. The back contact solar cell according to claim 5, characterized in that: The lateral width of the first segment is 1 micrometer to 45 micrometers, the lateral width of the second segment is 0.2 micrometer to 8 micrometers, and the lateral width of the fifth segment is 0.5 micrometer to 10 micrometers.

7. The back contact solar cell according to claim 1, characterized in that: The second edge isolation region further includes a sixth segment, and the sixth segment is located between the fourth segment and the P-type doping layer.

8. The back contact solar cell according to claim 7, characterized in that: The lateral width of the third segment is 5 micrometers to 50 micrometers, the lateral width of the fourth segment is 5 micrometers to 250 micrometers, and the lateral width of the sixth segment is 0.5 micrometers to 10 micrometers.

9. The back contact solar cell according to claim 1, characterized in that: The lateral width of the first edge isolation region is 2 micrometers to 50 micrometers, and the lateral width of the second edge isolation region is 20 micrometers to 300 micrometers; or, The lateral width of the second edge isolation region is greater than that of the first edge isolation region.

10. The back contact solar cell according to claim 1, characterized in that: The first velvet structure has a different morphology from the second velvet structure on the third segment.

11. The back-contact solar cell according to any one of claims 1 to 10, characterized in that: The first velvet structure includes: a plurality of first-type pyramid structures; the second velvet structure on the third segment includes: a plurality of second-type pyramid structures; The distribution density of the first type of pyramid structures is less than the distribution density of the second type of pyramid structures; or The average interval between adjacent pyramid structures of the first type is greater than the average interval between adjacent pyramid structures of the second type; or, The apex angle of the first type of pyramid structure is greater than the apex angle of the second type of pyramid structure; or The aspect ratio of the first type of pyramid structure is smaller than the aspect ratio of the second type of pyramid structure.

12. The back contact solar cell according to claim 11, characterized in that: The second surface has a third velvet structure; the third velvet structure includes: a plurality of third type pyramid structures; The top angle of the second type of pyramid structure is greater than the top angle of the third type of pyramid structure.

13. The back-contact solar cell according to any one of claims 1 to 10, characterized in that: In an orthographic projection of the substrate, a projection area of ​​the first velvet structure is smaller than a projection area of ​​the second velvet structure.

14. The back-contact solar cell according to any one of claims 1 to 10, characterized in that: A contour line of the first edge isolation region on the sidewall includes a wavy segment.

15. The back contact solar cell according to claim 11, characterized in that: The first surface includes: a third isolation region located between the adjacent N-type doped layer and the P-type doped layer; the third isolation region has a fourth velvet structure, and the fourth velvet structure includes: a plurality of fourth-type pyramid structures; the size of the fourth-type pyramid structure is larger than the size of the second-type pyramid structure.

16. The back contact solar cell according to claim 5, characterized in that: A surface of the first segment and a surface of the second segment have a first angle, a side wall of the fifth segment and a surface of the second segment have a second angle, and the first angle is greater than the second angle.

17. A photovoltaic module, characterized in that: include: A back-contact solar cell as claimed in any one of claims 1 to 16.

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