Photovoltaic cell and photovoltaic module

Abstract

The embodiment of the invention provides a photovoltaic cell and a photovoltaic module. The photovoltaic cell piece comprises a silicon substrate, the silicon substrate comprises a backlight surface and a light receiving surface which are arranged oppositely along a first direction, and a side surface connected with the backlight surface and the light receiving surface, and the side surface comprises a cutting surface and a non-cutting surface; wherein a first conductive region is arranged on the backlight surface, a first isolation groove is formed between the first conductive region and the cutting surface, a height difference exists between the surface of the first isolation groove and the surface of the first conductive region, and a connecting side surface is arranged between the first conductive region and the first isolation groove; the first doped conductive layer is arranged in the first conductive region; and the first passivation layer covers the surface, far away from the silicon substrate, of the first doped conductive layer, the surface of the first isolation groove and the surface of the connecting side surface. According to the embodiment of the invention, the edge of the first doped conductive layer can be prevented from being damaged. And moreover, the efficiency loss of the battery can be reduced.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic processing technology, and specifically to a photovoltaic cell and a photovoltaic module. Background Art

[0002] Photovoltaic cells are a key component of photovoltaic modules, and their manufacturing process directly affects the performance and cost of solar cells. Half-split and quarter-split cells are common photovoltaic cells, offering advantages such as low power loss and high output power and energy yield.

[0003] Currently, laser cutting is commonly used to cut full-cell cells into two half-cells or four quarter-cells, which are then packaged into photovoltaic modules. However, during the laser cutting process to form half-cells or quarter-cells, the doped layers adjacent to the cut surfaces are easily damaged. Furthermore, significant carrier recombination occurs between the cell edges near the cut surfaces, significantly increasing cell efficiency losses. Summary of the Invention

[0004] The present application aims to provide a photovoltaic cell and a photovoltaic module to solve the problem of large efficiency loss near the cutting surface of the existing cell.

[0005] In order to solve the above technical problems, this application is implemented as follows: In a first aspect, the present application discloses a photovoltaic cell, comprising: a silicon substrate, the silicon substrate comprising a backlight surface and a light-receiving surface disposed in a first direction away from each other, and a side surface connecting the backlight surface and the light-receiving surface, the side surface comprising a cutting surface and a non-cutting surface; wherein, A first conductive area is provided on the backlight surface, a first isolation groove is provided between the first conductive area and the cutting surface, a height difference is provided between the surface of the first isolation groove and the surface of the first conductive area, and a connecting side surface is provided between the first conductive area and the first isolation groove; a first doped conductive layer, wherein the first doped conductive layer is disposed in the first conductive region; A first passivation layer covers a surface of the first doped conductive layer away from the silicon substrate, a surface of the first isolation trench, and a surface of the connection side surface.

[0006] Optionally, the height difference is a first height, and the first height ranges from 1 micron to 10 microns.

[0007] Optionally, a surface of the first isolation trench is provided with a pyramid structure or a texture structure.

[0008] Optionally, there are multiple first conductive areas, and multiple groove areas are further provided on the backlight surface. The multiple first conductive areas and the multiple groove areas are alternately provided on the backlight surface along a second direction, and the second direction is perpendicular to the cutting surface. The width of the first isolation trench along the second direction is a first width, the width of the recess region along the second direction is a second width, and the first width is smaller than the second width.

[0009] Optionally, a ratio of the first width to the second width ranges from 25% to 75%.

[0010] Optionally, there are multiple first conductive areas, and multiple groove areas are further provided on the backlight surface. The multiple first conductive areas and the multiple groove areas are alternately provided on the backlight surface along a second direction, and the second direction is perpendicular to the cutting surface. The height difference between the surface of the first isolation groove and the surface of the first conductive area is a first height, the height difference between the surface of the groove area and the surface of the first conductive area is a second height, and the difference between the first height and the second height is less than or equal to 1 micron.

[0011] Optionally, along the extension direction of the cutting surface, the length of the first isolation groove accounts for 50% to 100% of the length of the cutting surface.

[0012] Optionally, the cutting surface includes a first cutting surface and a second cutting surface, and the first cutting surface and the second cutting surface are arranged opposite to each other; A second isolation trench is further provided between the second cutting surface and the first conductive region, and a height difference exists between a surface of the second isolation trench and a surface of the first conductive region; The first passivation layer is disposed on a surface of the second isolation trench.

[0013] Optionally, along the extension length direction of the first isolation groove, the first isolation groove includes a middle area and edge areas arranged on both sides of the middle area, the edge areas are provided with cutting grooves, and the recessed depth of the cutting grooves is greater than the recessed depth of the middle area.

[0014] Optionally, along the extension direction of the first isolation trench, the first isolation trench includes a middle region and edge regions provided on both sides of the middle region, the edge regions are provided with cutting grooves, and the width of the cutting grooves is smaller than the width of the first isolation trench; And / or, the length of the cutting groove ranges from 1 mm to 5 mm.

[0015] Optionally, the light-receiving surface includes a second conductive region, and the second conductive region is provided with a second doped conductive layer; A third isolation trench is provided between the second conductive area and the cutting surface, and a height difference is formed between a surface of the third isolation trench and a surface of the second conductive area, wherein the height difference ranges from 1 micron to 10 microns; The first isolation groove and the third isolation groove are correspondingly arranged along the thickness direction of the photovoltaic cell; The first passivation layer is disposed on a side of the second doped conductive layer away from the silicon substrate and on a surface of the third isolation trench.

[0016] Optionally, the photovoltaic cell further comprises a second passivation layer, and the second passivation layer is located on the surface of the cut surface; The second passivation layer extends to the backlight surface and is located on the side of the first passivation layer away from the silicon substrate, and the second passivation layer at least covers the first isolation groove and the first conductive area adjacent to the first isolation groove, and the second passivation layer covers the side of the first doped conductive layer away from the silicon substrate.

[0017] Optionally, the photovoltaic cell further comprises a second passivation layer, and the second passivation layer is located on the surface of the cut surface; The second passivation layer extends to the backlight surface and is located on a side of the first passivation layer away from the silicon substrate. The second passivation layer at least covers the first isolation trench and the first conductive region adjacent to the first isolation trench, and covers a side of the first doped conductive layer away from the silicon substrate. The second passivation layer extends to the light-receiving surface and is located on the side of the first passivation layer away from the silicon substrate, and the second passivation layer at least covers the third isolation groove and the second conductive area adjacent to the third isolation groove, and the second passivation layer covers the side of the second doped conductive layer away from the silicon substrate.

[0018] Optionally, a fourth isolation trench is further provided between the first conductive area and the non-cutting surface; A difference between a surface height of the fourth isolation trench and a surface height of the first conductive region is less than 1 micrometer, and a width of the fourth isolation trench is smaller than a width of the first isolation trench.

[0019] In a second aspect, the present application further discloses a photovoltaic assembly, comprising: a plurality of battery strings; The cell string comprises a plurality of photovoltaic cells as described in any one of the above items and a plurality of interconnecting elements; The photovoltaic cells are electrically connected via the interconnectors.

[0020] In the embodiments of the present application, a first isolation trench is provided between the first conductive region of the backlight surface of the photovoltaic cell and the cut surface. During the slicing process of the photovoltaic cell, the first isolation trench prevents the slicing force generated by the cut surface from being transmitted to the first doped conductive layer, thereby preventing damage to the edges of the first doped conductive layer. Furthermore, the first isolation trench can also cut off the carrier transmission path from the first conductive region to the cut surface, suppressing significant carrier recombination on the cut surface and at the edges near the cut surface, thereby reducing cell efficiency losses.

[0021] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which: Figure 1 This is a schematic diagram of the light-receiving surface structure of a photovoltaic cell according to an embodiment of the present application; Figure 2 yes Figure 1 Schematic diagram of the backlight structure of the photovoltaic cell shown; Figure 3 yes Figure 1 Schematic diagram of the cross-sectional structure of the photovoltaic cell shown; Figure 4 This is a schematic diagram of the backlight structure of another photovoltaic cell according to an embodiment of the present application; Figure 5 yes Figure 4 Schematic diagram of the cross-sectional structure of the photovoltaic cell shown; Figure 6 It is a schematic diagram of the cross-sectional structure of another photovoltaic cell described in an embodiment of the present application.

[0023] Figure numerals: 10-silicon substrate, 101-backlight surface, 102-light receiving surface, 103-cutting surface, 1031-first cutting surface, 1032-second cutting surface, 104-first conductive area, 105-first isolation groove, 106-first passivation layer, 107-tunneling layer, 108-first doped conductive layer, 109-second conductive area, 1010-second isolation groove, 1011-non-cutting surface, 1012-second doped conductive layer, 1013-third isolation groove, 110-second passivation layer, 111-groove area, X-first direction, Y-second direction, W1-first width, W2-second width. DETAILED DESCRIPTION

[0024] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention and are not to be construed as limiting the present invention. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of this application.

[0025] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly refer to one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more. Furthermore, the term "and / or" in the specification and claims refers to at least one of the connected entities, and the character " / " generally indicates an "or" relationship between the connected entities.

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0027] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0028] Reference Figure 1 , shows a schematic diagram of the light-receiving surface structure of a photovoltaic cell according to an embodiment of the present application, with reference to Figure 2 , showing Figure 1 The backlight structure diagram of the photovoltaic cell shown in FIG. Figure 3 , showing Figure 1 The cross-sectional structure diagram of the photovoltaic cell shown in FIG. Figure 4 , shows a schematic diagram of the backlight structure of another photovoltaic cell according to an embodiment of the present application, referring to Figure 5 , showing Figure 4 Schematic diagram of the cross-sectional structure of the photovoltaic cell shown.

[0029] like Figures 1 to 5 As shown, the photovoltaic cell may specifically include: a silicon substrate 10, the silicon substrate 10 may include a backlight surface 101 and a light-receiving surface 102 arranged in a first direction X away from each other, and a side surface connecting the backlight surface 101 and the light-receiving surface 102, the side surface may include a cutting surface 103 and a non-cutting surface 1011; wherein, a first conductive area 104 is provided on the backlight surface 101, a first isolation groove 105 is provided between the first conductive area 104 and the cutting surface 103, a height difference is provided between the surface of the first isolation groove 105 and the surface of the first conductive area 104, and a connecting side surface is provided between the first conductive area 104 and the first isolation groove 105; a first doped conductive layer 108, the first doped conductive layer 108 is provided in the first conductive area 104.

[0030] In the embodiment of the present application, since a first isolation trench 105 is provided between the first conductive region 104 of the backlight surface 101 of the photovoltaic cell and the cut surface 103, during the slicing process of the photovoltaic cell, the first isolation trench 105 can prevent the force generated by the cut surface 103 from being transmitted to the edge of the first doped conductive layer 108 near the cut surface 103, thereby preventing damage to the edge of the first doped conductive layer 108 and the formation of carrier recombination centers. Furthermore, the first isolation trench 105 can also cut off the carrier transmission channel from the first conductive region 104 to the cut surface 103, suppressing significant carrier recombination at the cut surface and the edge near the cut surface 103, thereby reducing cell efficiency loss.

[0031] In a specific application, a first doped conductive layer 108 can be deposited as a whole layer on the backlight surface 101 of the entire cell, and an inner expansion layer of a certain depth can be formed on the backlight surface 101 of the silicon substrate 10, and a doped glass layer can be formed on the surface of the first doped conductive layer 108. In the area where the entire cell needs to be sliced, the first doped conductive layer 108 on the area is removed, that is, a first isolation groove 105 can be formed between the first conductive area 104 and the cutting surface 103. Specifically, the doped glass layer in the area of ​​the first isolation groove 105 can be formed by laser etching first, and then the residue on the surface of the area where the first isolation groove 105 is formed can be removed by a wet method, and part of the silicon substrate in the area can be etched downward to finally form the first isolation groove 105. In the wet process, the area outside the first isolation groove 105 is formed because the outermost side is covered with a doped glass layer, and the first doped conductive layer in this part will not react with the solution. As Figure 3 and Figure 5As shown, the first doped conductive layer 108 is not provided in the region corresponding to the first isolation trench 105. The surface of the first isolation trench 105 is lower than the surface of the first conductive region 104, that is, there is a height difference between the surface of the first isolation trench 105 and the surface of the first conductive region 104. In actual applications, a connecting side surface is provided between the first conductive region 104 and the first isolation trench 105. The connecting side surface can be a vertical side surface or an inclined side surface. The embodiment of the present application does not specifically limit the shape of the connecting side surface.

[0032] In an embodiment of the present application, the height difference between the surface of the first conductive region 104 and the surface of the first isolation trench 105 can ensure that in the process of forming the first isolation trench 105, the inner expansion layer in the area of ​​the first isolation trench 105 is completely removed, further cutting off the transmission channel of the photogenerated carriers from the inner expansion layer to the cutting surface 103, thereby suppressing significant carrier recombination at the cutting surface and the edge position near the cutting surface 103, thereby reducing the battery efficiency loss.

[0033] In specific applications, the silicon substrate 10 can serve as the structural main body of the photovoltaic cell. The material of the silicon substrate 10 may include one or more of single crystal silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In some embodiments, the material of the silicon substrate 10 may also be silicon carbide, an organic material, or a multi-component compound. The multi-component compound may include, but is not limited to, perovskite, gallium arsenide, cadmium telluride, copper indium selenide, and the like.

[0034] Exemplarily, the silicon substrate 10 in the present application is a single crystal silicon substrate. The silicon substrate 10 contains doping elements, and the conductivity type of the doping elements can be N-type or P-type. The N-type element can be a V-group element such as phosphorus (P), bismuth (Bi), antimony (Sb) or arsenic (As), and the P-type element can be a III-group element such as boron (B), aluminum (Al), gallium (Ga) or indium (In). For example, when the silicon substrate 10 is a P-type silicon substrate, the conductivity type of the doping elements inside it is P-type. For another example, when the silicon substrate 10 is an N-type silicon substrate, the conductivity type of the doping elements inside it is N-type. Exemplarily, in the embodiment of the present application, the silicon substrate 10 can be an N-type silicon substrate to improve the conversion efficiency of the solar cell and reduce the manufacturing cost.

[0035] In the embodiment of the present application, the photovoltaic cell can be applied to various types of cell structures, including but not limited to tunnel oxide passivated contact cells (TOPCon), interdigitated back contact cells (IBC), and passivated emitter rear cell (PERC). The light-receiving surface 102 described in the embodiment of the present application can be the front side of the photovoltaic cell for receiving sunlight, and the backlight surface 101 can be the back side of the photovoltaic cell away from sunlight.

[0036] In practical applications, when cutting the full-cell into the half-cell or quarter-cell, laser cutting can be used to form the photovoltaic cell described in the embodiment of the present application. The side surface of the photovoltaic cell formed by laser cutting is the cutting surface 103, while the side surface directly formed from the side surface of the original full-cell can be the non-cutting surface 1011.

[0037] For example, Figures 1 to 3 In the half-cut cell shown in FIG, the four side surfaces of the photovoltaic cell may include one cutting surface 103 and three non-cutting surfaces 1011. Figure 4 and Figure 5 In the illustrated four-slice photovoltaic cell, the four side surfaces of the photovoltaic cell may include two cut surfaces 103 and two non-cut surfaces 1011 .

[0038] In a specific application, the backlight surface 101 of the cell includes a first conductive area 104 , on which a tunneling layer 107 , a first doped conductive layer 108 and an electrode are disposed, and the electrode is electrically connected to the first doped conductive layer 108 .

[0039] In the embodiment of the present application, after forming the first isolation trench 105, a first passivation layer 106 may be further formed on the surface of the first doped conductive layer 108 away from the silicon substrate 10, the surface of the first isolation trench 105, and the surface of the connecting side surface. The first passivation layer 106 may be used to achieve surface passivation of the first isolation trench 105 and the first doped conductive layer 108. The electrode may be electrically connected to the first doped conductive layer 108 by burning through at least a portion of the first passivation layer 106 below the electrode through a high-temperature sintering process, or the first passivation layer 106 below the electrode may be first removed using a laser or etching paste, and then the electrode may be provided to achieve electrical connection between the electrode and the first doped conductive layer 108.

[0040] In specific applications, since the first isolation groove 105 can make the edge of the first doped conductive layer 108 close to the cutting surface 103 away from the cutting position of the laser slicing during the slicing process, the damage to the surface of the first doped conductive layer 108 or the surface of the first isolation groove 105 caused by particles splashed during the laser slicing process is reduced; in addition, the first passivation layer 106 can cover part of the surface and edge of the first doped conductive layer 108 of the first conductive region 104, the first isolation groove 105 and the connecting side surface, effectively compounding the dangling bonds or other defects on these surfaces, reducing the recombination on the surface of the photovoltaic cell, and improving the cell efficiency.

[0041] For example, the first passivation layer 106 may also be provided on the light-receiving surface 102, the cut surface 103, and the non-cut surface 1011 of the silicon substrate 10. The material of the first passivation layer 106 may include, but is not limited to, at least one of aluminum oxide, silicon nitride, silicon oxynitride, and silicon dioxide. The first passivation layer 106 may be a stacked structure of one or more of the above materials. The embodiment of the present application does not specifically limit the material of the first passivation layer 106. For example, the structure of the first passivation layer 106 may be a stacked structure of aluminum oxide, silicon nitride, and silicon oxynitride.

[0042] It should be noted that the stacking structure and thickness of the first passivation layer on the light-receiving surface 102 and the backlight surface 101 of the silicon substrate 10 may be the same or different, and this embodiment of the present application does not specifically limit this.

[0043] Optionally, the height difference is a first height, and the first height ranges from 1 micron to 10 microns. By setting the depth of the first isolation trench 105 within the range of 1 to 10 microns, it is possible to ensure that the inner expansion layer formed in the silicon substrate 10 below the first doped conductive layer 108 is removed, cutting off the transmission path of photogenerated carriers from the inner expansion layer to the cut surface 103. In addition, the influence of the doping elements of the inner expansion layer on the passivation effect of the first passivation layer 106 is reduced.

[0044] For example, the first height can be 1 micron, 2 microns, 5 microns, 8.5 microns, and 10 microns, etc., and the embodiment of the present application does not specifically limit the value of the first height. Preferably, the depth of the first isolation trench 105 is set in the range of 2 to 6 microns.

[0045] Reference Figure 6 , shows a schematic cross-sectional structure diagram of another photovoltaic cell according to an embodiment of the present application, such as Figure 6As shown, when a first conductive region 104 is provided on the backlight surface 101, a first doped conductive layer 108 is provided on the first conductive region 104, a second conductive region 109 is provided on the light-receiving surface 102, and a second doped conductive layer 1012 is provided on the second conductive region 109, a third isolation trench 1013 can be provided between the second conductive region 109 and the cutting surface 103. By controlling the depth of the first isolation trench 105 and the third isolation trench 1013 within the above range, the inner expansion layer can be removed. During the laser slicing process, reducing the pushing effect of the laser thermal effect on the inner expansion layer can reduce the probability of doped conductive layers of different polarities contacting on the cutting surface 103, reducing the risk of leakage at the edge of the cell.

[0046] It should be noted that the material of the first doped conductive layer 108 and the second doped conductive layer 1012 may include at least one semiconductor material selected from the group consisting of single crystal silicon, polycrystalline silicon, microcrystalline silicon, and amorphous silicon. The doping type of the doped conductive layer may be N-type or P-type. Specifically, an N-type doped conductive layer may be obtained by introducing the aforementioned donor impurities into these semiconductor materials, or a P-type doped conductive layer may be obtained by introducing the aforementioned acceptor impurities into these semiconductor materials. Specifically, the first doped conductive layer 108 may be an N-type doped polycrystalline silicon layer, and the second doped conductive layer 1012 may be a P-type doped single crystal silicon layer. That is, a P-type diffusion layer is formed on the surface of the silicon substrate by diffusion or other means. In this case, the surface of the second doped conductive layer 1012 is co-surface with the surface of the second conductive region 109.

[0047] In some optional embodiments of the present application, a pyramid structure or a texture structure is provided on the surface of the first isolation trench 105 to reduce the reflectivity of the first isolation trench 105 and improve the light absorption efficiency of the first isolation trench 105 .

[0048] In some optional embodiments of the present application, a pyramid structure or a texture structure is provided on the surface of the third isolation trench 1013 to reduce the reflectivity of the third isolation trench 1013 and improve the light absorption efficiency of the third isolation trench 1013 .

[0049] In some optional embodiments of the present application, the texture structure may be presented as a pit structure recessed in the surface of the first isolation groove 105 or the third isolation groove 1013, and the projection shape of its bottom surface or opening is rectangular, rhombus, parallelogram, approximate rectangle, approximate rhombus or parallelogram structure. The bottom surface size range of the texture structure is 1 to 10 microns, specifically 1 micron, 2 microns, 5 microns, 8.5 microns and 10 microns. The bottom surface size can be the distance between the long side, short side, diagonal or farthest point of the bottom surface or opening projection shape, and is not specifically limited here. The bottom surface size of the texture structure can be the size of the bottom surface size of a single texture structure or the average value of the bottom surface size of the texture structure within a certain area.

[0050] In some optional embodiments of the present application, the dimensions of the pyramid structure include the base size or tower height of the pyramid structure. The base size of the pyramid structure ranges from 1 to 3 microns. The base size to the longest side, short side, diagonal, or end points of the projection of the pyramid structure base on the backlight surface can be 1 micron, 1.5 microns, 2 microns, 2.5 microns, or 3 microns. The tower height of the pyramid structure refers to the vertical distance from the top of the pyramid structure to the base, and can be 1 micron, 1.5 microns, 2 microns, 2.5 microns, or 3 microns. The dimensions of the pyramid structure include the base size or tower height of a single pyramid structure or the average of the base size or tower height of the pyramid structures within a certain area.

[0051] like Figure 2 and Figure 4 As shown, there are multiple first conductive areas 104, and multiple groove areas 111 are also provided on the backlight surface 101. The multiple first conductive areas 104 and the multiple groove areas 111 are alternately provided along the second direction Y on the backlight surface 101, and the second direction Y is perpendicular to the cutting surface 103. Figure 3 and Figure 5 As shown, the width of the first isolation trench 105 along the second direction Y is a first width W1 , the width of the recess region 111 along the second direction Y is a second width W2 , and the first width W1 is smaller than the second width W2 .

[0052] In practical applications, the recessed region 111 primarily serves to reduce the negative impact of parasitic absorption caused by the doped conductive layer on cell efficiency and to increase the area of ​​the backlight surface 101 receiving incident light. The first isolation trench 105, on the other hand, primarily serves to prevent stress transfer and reduce carrier recombination. Therefore, while meeting operational requirements, setting the area of ​​the first isolation trench 105 smaller than the width of the recessed region 111 can increase the area of ​​the first conductive region 104 while still meeting other structural requirements. Furthermore, since printing grid lines at the cell edge is more prone to offset, increasing the width of the first conductive region 104 at the edge can reduce alignment difficulties during subsequent electrode printing.

[0053] Optionally, the ratio of the first width W1 to the second width W2 is in the range of 25%-75%, so that the first isolation groove 105 can prevent the stress of the cutting surface 103 from being transferred to the first doped conductive layer 108, avoid damage to the edge of the first doped conductive layer 108 and carrier recombination, and at the same time, reduce the impact of the setting of the first isolation groove 105 on the energy collection of the photovoltaic cell.

[0054] In some optional embodiments of the present application, the first width W1 ranges from 150 to 700 microns, and specifically may be 150 microns, 200 microns, 250 microns, 300 microns, 400 microns, 500 microns, 600 microns, or 700 microns. The second width W2 ranges from 400 to 1500 microns, and specifically may be 400 microns, 500 microns, 600 microns, 700 microns, 800 microns, 900 microns, 1100 microns, 1300 microns, or 1500 microns.

[0055] In a specific application, there are multiple first conductive areas 104, and multiple groove areas 111 are also provided on the backlight surface 101. The multiple first conductive areas 104 and the multiple groove areas 111 are alternately arranged along the second direction Y on the backlight surface 101, and the second direction Y is perpendicular to the cutting surface 103; wherein, the height difference between the surface of the first isolation groove 105 and the surface of the first conductive area 104 is a first height, and the height difference between the surface of the groove area 111 and the surface of the first conductive area 104 is a second height, and the difference between the first height and the second height is less than or equal to 1 micron, so that the height difference between the surface of the first isolation groove 105 and the surface of the groove area 111 is controlled within a reasonable range.

[0056] In practical applications, the first isolation trench 105 and the recessed area 111 can be formed in the same process to control the height difference between the two. This avoids the need for a separate process to form the first isolation trench 105, greatly simplifying the photovoltaic cell manufacturing process and reducing the photovoltaic cell manufacturing cost.

[0057] In the embodiment of the present application, along the extension direction of the cutting surface 103, the length of the first isolation groove 105 accounts for 50% to 100% of the length of the cutting surface 103, so as to increase the area of ​​the first conductive region 104 and prepare for the subsequent setting of the edge gate line, thereby reducing the contact resistance between the edge gate line and the silicon substrate 10.

[0058] In practical applications, when the length of the first isolation trench 105 accounts for 50% to 100% of the length of the cutting surface 103, it can be avoided that the length of the first isolation trench 105 is too short and cannot cut off the transmission channel of carriers from the first conductive region 104 or the inner expansion layer to the cutting surface 103.

[0059] In addition, the length of the first isolation trench 105 can be selected based on the actual electrode pattern. For example, the length of the first isolation trench 105 can account for 50%, 65%, 78%, 95%, or 100% of the length of the cutting surface 103. The embodiment of the present application does not specifically limit the ratio of the length of the first isolation trench 105 to the length of the cutting surface 103.

[0060] In practical applications, during the process of cutting the full-sheet cell into four-sheet cells, the photovoltaic cell at the head and tail ends has only one cutting surface 103 (e.g. Figures 1 to 3 As shown in FIG), the two photovoltaic cells located in the middle will have two cutting surfaces 103 (as shown in FIG). Figure 4 and Figure 5 shown).

[0061] like Figure 4 and Figure 5 As shown, the cutting surface 103 may specifically include a first cutting surface 1031 and a second cutting surface 1032, and the first cutting surface 1031 and the second cutting surface 1032 are arranged opposite to each other; a second isolation groove 1010 may also be included between the second cutting surface 1032 and the first conductive area 104, and there is a height difference between the surface of the second isolation groove 1010 and the surface of the first conductive area 104, and the height difference ranges from 2 microns to 6 microns; the first passivation layer 106 is arranged on the surface of the second isolation groove 1010.

[0062] In specific applications, the second isolation trench 1010 functions similarly to the first isolation trench 105. Because the second isolation trench 1010 is provided between the first conductive region 104 of the backlight surface 101 of the photovoltaic cell and the second cut surface 1032, during the slicing process of the photovoltaic cell, the second isolation trench 1010 can prevent the force generated by the second cut surface 1032 from being transmitted to the edge of the first doped conductive layer 108 near the second cut surface 1032, thereby preventing damage to the edge of the first doped conductive layer 108 and the formation of carrier recombination centers. Furthermore, the second isolation trench 1010 can also cut off the carrier transmission channel from the first conductive region 104 to the second cut surface 1032, suppressing significant carrier recombination at the cut surface and the edge near the second cut surface 1032, thereby reducing cell efficiency loss.

[0063] In addition, the height difference control principle between the second isolation trench 1010 and the surface of the first conductive region 104, the width of the second isolation trench 1010, the structure of the first passivation layer 106 and the description of related beneficial effects can refer to the description of the first isolation trench 105 mentioned above and will not be repeated here.

[0064] In some optional embodiments of the present application, along the extension direction of the first isolation trench 105, the first isolation trench 105 may include a middle region and edge regions disposed on both sides of the middle region. The edge regions are provided with cutting grooves, and the recessed depth of the cutting grooves is greater than the recessed depth of the middle region of the first isolation trench 105. The deeper recessed depth of the cutting grooves increases the likelihood of cell breakage in the edge regions during laser slicing, thereby reducing the difficulty of slicing the cell into half-cells. Furthermore, the deeper recesses are controlled in the edge regions to minimize damage to the cell surface by laser or wet slicing, thereby reducing cutting damage.

[0065] In a specific application, the first isolation groove 105 is located on the backlight surface 101 of the photovoltaic cell, and the active area of ​​the laser slicing can be the backlight surface 101 of the photovoltaic cell. In this case, the impact on the velvet surface on the front side of the photovoltaic cell can be reduced, ensuring the consistency of the light trapping effect of the velvet structure on the light-receiving surface 102. Due to the height difference between the first isolation groove 105 and the first conductive area 104, during the laser slicing process, it can help the laser to be positioned and improve the accuracy of the laser action. In addition, the reduced depth of the middle area of ​​the first isolation groove 105 can thin the photovoltaic cell in advance before laser slicing, reducing the difficulty of laser slicing.

[0066] Optionally, the width of the cutting groove is smaller than the width of the middle area of ​​the first isolation groove 105. Since the cutting groove is formed to a deeper depth, its width needs to be controlled so that it is within the first isolation groove 105, thereby reducing cutting damage by controlling the size of its affected area.

[0067] In practical applications, during the laser slicing process, a laser can be used to form a cutting groove about 5 mm long in the edge area of ​​the first isolation groove 105. Since the height of the surface of the first isolation groove 105 is less than the height of the surface of the first conductive area, the edge area can help the laser to position and improve the accuracy of the laser action.

[0068] Optionally, the edge region of the first isolation groove 105 has a length ranging from 1 mm to 5 mm, and cutting damage is reduced by controlling the size of the laser-affected region.

[0069] For example, the edge area length of the first isolation groove 105 can be 1 mm, 1.8 mm, 2.5 mm, 3.2 mm or 5 mm, etc. The embodiment of the present application does not specifically limit the length of the cutting groove.

[0070] In some optional embodiments of the present application, such as Figure 6As shown, the light-receiving surface 102 may include a second conductive region 109, which is provided with a second doped conductive layer 1012. A third isolation trench 1013 is provided between the second conductive region 109 and the cut surface 103. The surface of the third isolation trench 1013 has a height difference with the surface of the second conductive region 109, and the height difference ranges from 2 microns to 10 microns. The first isolation trench 105 and the third isolation trench 1013 are correspondingly provided along the thickness direction of the photovoltaic cell. A first passivation layer 106 is provided on the side of the second doped conductive layer 1012 away from the silicon substrate 10 and on the surface of the third isolation trench 1013.

[0071] In a specific application, the second doped conductive layer 1012 near the edge of the cut surface 103 on the light-receiving surface 102 is removed to cut off the transmission channel of carriers to the cut surface 103 , thereby suppressing carrier recombination caused by defects in the cut surface 103 .

[0072] In specific applications, when the doping type of the second doped conductive layer 1012 is P-type, the second doped conductive layer 1012 on the light-receiving surface 102 of the photovoltaic cell forms a PN junction with the silicon substrate 10. In this case, the second doped conductive layer 1012 on the edge of the light-receiving surface 102 near the cut surface 103 is removed, cutting off the carrier transmission path to the cut surface 103. This can inhibit carrier recombination caused by defects on the cut surface 103, reduce the negative impact of carriers in the P-type doped layer on the field passivation effect of passivation layer materials such as aluminum oxide, and improve the passivation effect on the cut surface 103. This structure can be applied to batteries to reduce dark current loss, increase open-circuit voltage and fill factor, and improve photoelectric conversion efficiency.

[0073] In actual applications, the formation method of the third isolation groove 1013, the realization method and beneficial effects of the height difference between the surface of the third isolation groove 1013 and the surface of the second conductive region 109, and the setting method and effect of the first passivation layer 106 can refer to the first isolation groove 105, the first conductive region 104 and the first passivation layer 106 in the aforementioned embodiment, and will not be elaborated here.

[0074] It should be noted that when the second doped conductive layer 1012 is a doped single crystal silicon layer, the depth of its diffusion in the silicon substrate 10 is greater than the depth of the inner expansion layer formed in the silicon substrate below the first doped conductive layer 108. Therefore, the minimum height difference formed between the surface of the third isolation trench 1013 and the surface of the second conductive region 109 should be greater than the minimum height difference formed between the surface of the first isolation trench 105 and the surface of the first conductive region 104.

[0075] In some optional embodiments of the present application, such as Figure 3 、 Figure 5 as well as Figure 6As shown, the photovoltaic cell may further include a second passivation layer 110, which is located on the surface of the cut surface 103; the second passivation layer 110 extends to the backlight surface 101, and is located on the side of the first passivation layer 106 away from the silicon substrate 10, and the second passivation layer 110 at least covers the first isolation trench 105 and the first conductive region 104 adjacent to the first isolation trench 105, and the second passivation layer 110 covers the side of the first doped conductive layer 108 away from the silicon substrate 10.

[0076] In a specific application, the second passivation layer 110 may at least cover the cut surface 103 to passivate the surface of the cut surface 103. Since the second passivation layer 110 may also extend to the backlight surface 101 and cover the first isolation trench 105 and the first conductive region 104 adjacent to the first isolation trench 105, the second passivation layer 110 may further passivate the first isolation trench 105 and the side surfaces resulting from the recess of the first isolation trench 105 and the silicon substrate 10 portion of the first conductive region 104, thereby passivating the surface of such portions and further enhancing the surface passivation effect of the first isolation trench 105 and the first doped conductive layer 108 adjacent to the first isolation trench 105.

[0077] Specifically, the material of the second passivation layer 110 can be aluminum oxide, silicon oxide, silicon nitride, etc., and the present embodiment does not specifically limit the material of the second passivation layer 110. The thickness of the second passivation layer 110 can be selected from 60 to 150 nanometers as needed, and the present embodiment does not specifically limit the thickness of the second passivation layer 110.

[0078] In some optional embodiments of the present application, such as Figure 6 As shown, the photovoltaic cell may further include a second passivation layer 110, which is located on the surface of the cut surface 103; the second passivation layer 110 extends to the backlight surface 101, and is located on the side of the first passivation layer 106 away from the silicon substrate 10, and the second passivation layer 110 at least covers the first isolation groove 105 and the first conductive region 104 adjacent to the first isolation groove 105, and the second passivation layer 110 covers the side of the first doped conductive layer 108 away from the silicon substrate 10; the second passivation layer 110 extends to the light-receiving surface 102, and is located on the side of the first passivation layer 106 away from the silicon substrate 10, and the second passivation layer 110 at least covers the third isolation groove 1013 and the second conductive region 109 adjacent to the third isolation groove 1013, and the second passivation layer 110 covers the side of the second doped conductive layer 1012 away from the silicon substrate 10.

[0079] like Figure 6As shown, the second passivation layer 110 can at least cover the cut surface 103, passivating the surface of the cut surface 103. In addition, the second passivation layer 110 can not only extend to the backlight surface 101 and cover the first isolation trench 105 and the first doped conductive layer 108 on the first conductive region 104 adjacent to the first isolation trench 105, but can also extend to the light-receiving surface 102 and cover the third isolation trench 1013 and the second doped conductive layer 1012 on the second conductive region 109 adjacent to the third isolation trench 1013. In other words, the second passivation layer 110 can further passivate the side surface of the third isolation trench 1013 and the side surface formed by the recess of the third isolation trench 1013 and the silicon substrate 10 portion of the second conductive region 109, thereby achieving surface passivation of this portion and further improving the surface passivation effect of the third isolation trench 1013 and the second doped conductive layer 1012 adjacent to the third isolation trench 1013.

[0080] In some other optional embodiments of the present application, a fourth isolation trench is further provided between the first conductive region 104 and the non-cutting surface 1011; the difference between the surface height of the fourth isolation trench and the surface height of the first conductive region 104 is less than 1 micron, and the width of the fourth isolation trench is less than the width of the first isolation trench 105.

[0081] In specific applications, during the processing of the photovoltaic cell, the cell needs to float in the processing liquid. By providing the fourth isolation trench between the non-cut surface 1011 and the first conductive region 104, the processing liquid can be prevented from excessively etching the first doped conductive layer 108 at the upper edge of the backlight surface, thereby improving the yield of the photovoltaic cell during processing. By controlling the surface height of the fourth isolation trench to within 1 micron of the surface height of the first conductive region 104 and the width of the fourth isolation trench to be smaller than the width of the first isolation trench 105, the impact of the fourth isolation trench on the structure of the photovoltaic cell itself can be minimized.

[0082] In summary, the photovoltaic cell described in the embodiments of the present application can at least include the following advantages: In the embodiments of the present application, a first isolation trench is provided between the first conductive region of the backlight surface of the photovoltaic cell and the cut surface. During the slicing process of the photovoltaic cell, the first isolation trench can prevent the force generated by the cut surface from being transmitted to the edge of the first doped conductive layer near the cut surface, thereby preventing damage to the edge of the first doped conductive layer and the formation of carrier recombination centers. Furthermore, the first isolation trench can also cut off the transmission path of carriers from the first conductive region to the cut surface, suppressing significant carrier recombination at the cut surface and the edge near the cut surface, thereby reducing cell efficiency losses.

[0083] The present application also provides a photovoltaic assembly, which may include: a plurality of cell strings; the cell strings include a plurality of photovoltaic cells described in any of the above embodiments and a plurality of interconnecting components; the photovoltaic cells are electrically connected via the interconnecting components. Specifically, the interconnecting components may be conductive components such as photovoltaic ribbons.

[0084] It should be noted that in the embodiment of the present application, the structure of the photovoltaic cell in the photovoltaic assembly is the same as the structure of the photovoltaic cell described in any of the above embodiments, and its beneficial effects are also similar, which is not limited here.

[0085] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0086] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A photovoltaic cell, characterized in that: The photovoltaic cell comprises: a silicon substrate, the silicon substrate comprising a backlight surface and a light-receiving surface arranged in a first direction away from each other, and a side surface connecting the backlight surface and the light-receiving surface, the side surface comprising a cutting surface and a non-cutting surface; wherein, A first conductive area is provided on the backlight surface, a first isolation groove is provided between the first conductive area and the cutting surface, a height difference is provided between the surface of the first isolation groove and the surface of the first conductive area, and a connecting side surface is provided between the first conductive area and the first isolation groove; a first doped conductive layer, wherein the first doped conductive layer is disposed in the first conductive region; A first passivation layer covers a surface of the first doped conductive layer away from the silicon substrate, a surface of the first isolation trench, and a surface of the connection side surface.

2. The photovoltaic cell according to claim 1, characterized in that: The height difference is a first height, and the first height ranges from 1 micrometer to 10 micrometers.

3. The photovoltaic cell according to claim 1, characterized in that: A surface of the first isolation trench is provided with a pyramid structure or a texture structure.

4. The photovoltaic cell according to claim 1, characterized in that: There are multiple first conductive areas, and multiple groove areas are further provided on the backlight surface. The multiple first conductive areas and the multiple groove areas are alternately provided on the backlight surface along a second direction, and the second direction is perpendicular to the cutting surface. The width of the first isolation trench along the second direction is a first width, the width of the recess region along the second direction is a second width, and the first width is smaller than the second width.

5. The photovoltaic cell according to claim 4, characterized in that: The ratio of the first width to the second width ranges from 25% to 75%.

6. The photovoltaic cell according to claim 1, characterized in that: There are multiple first conductive areas, and multiple groove areas are further provided on the backlight surface. The multiple first conductive areas and the multiple groove areas are alternately provided on the backlight surface along a second direction, and the second direction is perpendicular to the cutting surface. The height difference between the surface of the first isolation groove and the surface of the first conductive area is a first height, the height difference between the surface of the groove area and the surface of the first conductive area is a second height, and the difference between the first height and the second height is less than or equal to 1 micron.

7. The photovoltaic cell according to claim 1, characterized in that: Along the extending direction of the cutting surface, the length of the first isolation groove accounts for 50% to 100% of the length of the cutting surface.

8. The photovoltaic cell according to claim 1, characterized in that: The cutting surface includes a first cutting surface and a second cutting surface, and the first cutting surface and the second cutting surface are arranged opposite to each other; A second isolation trench is further provided between the second cutting surface and the first conductive region, and a height difference exists between a surface of the second isolation trench and a surface of the first conductive region; The first passivation layer is disposed on a surface of the second isolation trench.

9. The photovoltaic cell according to claim 1, characterized in that: Along the extending length direction of the first isolation trench, the first isolation trench includes a middle area and edge areas arranged on both sides of the middle area, and the edge areas are provided with cutting grooves; The recessed depth of the cutting groove is greater than the recessed depth of the middle region of the first isolation groove.

10. The photovoltaic cell according to claim 1, characterized in that: Along the extending length direction of the first isolation trench, the first isolation trench includes a middle area and edge areas arranged on both sides of the middle area, and the edge areas are provided with cutting grooves; The width of the cutting groove is smaller than the width of the first isolation groove; And / or, the length of the cutting groove ranges from 1 mm to 5 mm.

11. The photovoltaic cell according to claim 1, characterized in that: The light receiving surface includes a second conductive area, and the second conductive area is provided with a second doped conductive layer; A third isolation trench is provided between the second conductive area and the cutting surface, and a height difference is formed between a surface of the third isolation trench and a surface of the second conductive area, wherein the height difference ranges from 2 microns to 10 microns; The first isolation groove and the third isolation groove are correspondingly arranged along the thickness direction of the photovoltaic cell; The first passivation layer is disposed on a side of the second doped conductive layer away from the silicon substrate and on a surface of the third isolation trench.

12. The photovoltaic cell according to claim 1, characterized in that: The photovoltaic cell further comprises a second passivation layer, and the second passivation layer is located on the surface of the cut surface; The second passivation layer extends to the backlight surface and is located on the side of the first passivation layer away from the silicon substrate, and the second passivation layer at least covers the first isolation groove and the first conductive area adjacent to the first isolation groove, and the second passivation layer covers the side of the first doped conductive layer away from the silicon substrate.

13. The photovoltaic cell according to claim 12, characterized in that: The photovoltaic cell further comprises a second passivation layer, and the second passivation layer is located on the surface of the cut surface; The second passivation layer extends to the backlight surface and is located on a side of the first passivation layer away from the silicon substrate. The second passivation layer at least covers the first isolation trench and the first conductive region adjacent to the first isolation trench, and covers a side of the first doped conductive layer away from the silicon substrate. The second passivation layer extends to the light-receiving surface and is located on the side of the first passivation layer away from the silicon substrate, and the second passivation layer at least covers the third isolation groove and the second conductive area adjacent to the third isolation groove, and the second passivation layer covers the side of the second doped conductive layer away from the silicon substrate.

14. The photovoltaic cell according to claim 1, characterized in that: A fourth isolation trench is further provided between the first conductive area and the non-cutting surface; A difference between a surface height of the fourth isolation trench and a surface height of the first conductive region is less than 1 micrometer, and a width of the fourth isolation trench is smaller than a width of the first isolation trench.

15. A photovoltaic module, characterized in that: The photovoltaic assembly includes: a plurality of battery strings; The cell string comprises a plurality of photovoltaic cells according to any one of claims 1 to 14 and a plurality of interconnectors; The photovoltaic cells are electrically connected via the interconnectors.

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