Solar cell and preparation method therefor, and photovoltaic module

Abstract

The present application relates to the technical field of solar cells, and discloses a solar cell and a preparation method therefor, and a photovoltaic module, used for solving the problem in the prior art of the photoelectric conversion efficiency of shingled solar cells being affected due to the passivation performance and other performance of shingled solar cells being affected by laser damage areas of the shingled solar cells. The solar cell comprises a first surface and a second surface opposite to each other, and a side surface connecting the first surface and the second surface. The side surface comprises at least one first area, the at least one first area comprising a plurality of fused silicon areas, and a first texture area between at least two fused silicon areas.

Description

Solar cell, preparation method thereof and photovoltaic module TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, and in particular to a solar cell, a preparation method thereof and a photovoltaic module. BACKGROUND

[0002] A solar cell is a device for converting solar energy into electricity through photoelectric effect or photochemical effect. The solar cell includes a split solar cell. Currently, the split solar cell is usually manufactured by cutting a solar cell having multiple film layers to divide the solar cell into at least two split solar cells, such as two half pieces. Then, the split solar cell is used to manufacture a photovoltaic module.

[0003] However, after cutting, the cutting surface of the split solar cell often has a laser damage area. For example, a guide groove for splitting is formed by melting a part of a silicon substrate of the solar cell by laser. At this time, the molten silicon recrystallizes and is partially oxidized during temperature drop, and silicon slag and silicon oxide are attached to the surface of the cutting surface. The above-mentioned situation affects the passivation performance of the split solar cell, and further affects the photoelectric conversion efficiency of the split solar cell. SUMMARY

[0004] The present application aims to provide a solar cell, a preparation method thereof and a photovoltaic module. By controlling the relative area and distribution form of the molten silicon area, the passivation performance and light absorption performance of the laser damage area are improved, so as to improve the photoelectric conversion efficiency of the solar cell.

[0005] In order to achieve the above-mentioned purpose, in a first aspect, the present application provides a solar cell. The solar cell includes opposite first and second surfaces, and a side surface connecting the first and second surfaces. The side surface includes at least one first area, the at least one first area includes a plurality of molten silicon areas, and a first textured area between the at least two molten silicon areas.

[0006] In actual production of solar cells, the side surface of a solar cell generally includes a "non-cutting side surface" which is not cut and a "cutting side surface" formed after cutting. The non-cutting side surface is generally not attached with silicon slag and silicon oxide, and even if attached, the amount is negligible. Therefore, the analysis focuses on the silicon slag and silicon oxide on the cutting side surface. An important source of the silicon slag and silicon oxide is that the silicon substrate of the solar cell is irradiated by a lossy laser during cutting of the cell, and the silicon substrate is melted and oxidized to form the silicon slag and silicon oxide. The part of the silicon slag and silicon oxide remaining after treatment is the molten silicon region in the present application. In the solar cell provided by the present application, the cutting side surface includes a first region, which is a laser cutting groove region (laser loss cutting region), and at least two molten silicon regions in the first region include a first textured region. Compared with the prior art in which the laser cutting groove region on the cutting surface is entirely covered with silicon slag and silicon oxide, the relative area of the molten silicon region in the present application is controlled to be within a reasonable range. Furthermore, the molten silicon region is also provided with a first textured region. The side surface of the first textured region and the molten silicon region can improve the light trapping effect of the side surface of the solar cell and increase the light absorption rate. Further, the relatively regular morphology of the first textured region can improve the film formation quality of the passivation layer and thus improve the passivation effect.

[0007] In an implementation manner, in the first region, the ratio of the total area of the molten silicon region to the total area of the first textured region is greater than or equal to 30% and less than or equal to 120%.

[0008] In the above technical solution, the ratio of the total area of the molten silicon region to the total area of the first textured region is within the above range, which not only reduces the complexity of the manufacturing process caused by the pursuit of too small total area of the molten silicon region, but also ensures the utilization rate of light by the side surface of the solar cell and optimizes the overall passivation effect of the first region, thereby improving the photoelectric conversion efficiency of the solar cell.

[0009] In an implementation manner, the plurality of molten silicon regions are distributed in the first region in an island shape; and / or, the maximum width of the molten silicon region is less than 100 microns.

[0010] In the above technical solution, the plurality of molten silicon regions are distributed in the first region in an isolated island shape. The plurality of island-shaped molten silicon regions are beneficial to reflecting more light to the first textured region through the side wall, thereby improving the light trapping effect of the cutting side surface of the solar cell, increasing the light absorption rate, and improving the utilization rate of light by the side surface of the solar cell. The maximum width of the molten silicon region is less than 100 microns, which can further limit the size of the molten silicon region and optimize the light trapping effect and light absorption efficiency.

[0011] In an implementation, a ratio of the width of the first region to the thickness of the solar cell is greater than or equal to 30% and less than or equal to 100%; the width direction of the first region and the thickness direction of the solar cell are both consistent with the direction from the first surface to the second surface.

[0012] In the case of using the above technical solution, when the ratio is greater than or equal to 30% or the ratio is equal to 100%, it can be ensured that the first region formed as a guide region effectively divides the whole solar cell into two split solar cells. Further, when the ratio is less than 100%, the damage of the solar cell caused by the lossy laser can be reduced.

[0013] In an implementation, the first region includes a groove structure.

[0014] In an implementation, the groove structure extends in any one or more of a dendritic shape, a straight line, a broken line, and a curve; and / or, the depth of the groove structure is 1-10 microns; and / or, the cross section of the groove structure is any one or more of a V shape and a U shape.

[0015] In an implementation, the molten silicon region includes a multi-layer structure arranged in a stack; and / or, the molten silicon region includes a porous structure; and / or, the molten silicon region includes an oxide of silicon.

[0016] In an implementation, the side surface further includes a second region, and the second region includes a second textured region.

[0017] In the case of using the above technical solution, it is beneficial to improve the light trapping effect of the second region, and it is beneficial to more light being refracted into the solar cell through the second region and being utilized by the solar cell. In addition, in the process of manufacturing the solar cell, a passivation layer will be formed on the second region of the side surface of the solar cell, and the texture structure of the second textured region is beneficial to the passivation effect, so as to improve the photoelectric conversion efficiency of the solar cell.

[0018] In an implementation, the side surface includes a cut side surface and a non-cut side surface. The first region is located on the cut side surface; and the second region is located on the cut side surface and / or the non-cut side surface.

[0019] In the technical scheme, when the first region and the second region are located on the cutting side surface of the solar cell, the cutting side surface comprises the molten silicon region, the first textured region and the second textured region. Compared with the prior art in which the laser guide groove region on the cutting surface is entirely silicon slag and silicon oxide, the relative area of the side molten silicon region is within a reasonable range by controlling the area and distribution form of the molten silicon region on the cutting side surface. In addition, the first textured region is further comprised between the molten silicon regions, and the second textured region is further comprised on the cutting side surface. The first textured region and the second textured region can improve the light trapping effect of the side surface of the solar cell and increase the light absorption rate. Further, the relatively regular form of the first textured region and the second textured region can improve the film forming quality of the passivation layer, thereby improving the passivation effect.

[0020] In an implementation manner, the first textured region comprises a textured structure, and the second textured region comprises a textured structure. The textured structure comprised by the first textured region and the textured structure comprised by the second textured region each comprises a pyramid structure.

[0021] In the technical scheme, when the textured structure on the first textured region and the second textured region is a pyramid structure, the specific surface area of the side surface where the first textured region and the second textured region are located can be increased. Based on this, the side surface where the first textured region and the second textured region are located has a good light trapping effect, and the utilization rate of light by the solar cell is further improved.

[0022] In an implementation manner, the average height of the pyramid structure of the first textured region is less than the average height of the pyramid structure of the second textured region, or the average base width of the pyramid structure of the first textured region is less than the average base width of the pyramid structure of the second textured region.

[0023] In the technical scheme, the passivation layer can be formed on the first textured region in the later stage, so as to improve the passivation effect of the solar cell and further improve the photoelectric conversion efficiency of the solar cell.

[0024] In an implementation manner, the first textured region comprises a tower base structure, and the second textured region comprises a tower base structure. The tower base transverse dimension of the tower base structure of the first textured region is less than the tower base transverse dimension of the tower base structure of the second textured region.

[0025] In the technical scheme, the passivation layer can be formed on the first textured region in the later stage, so as to improve the passivation effect of the solar cell and further improve the photoelectric conversion efficiency of the solar cell.

[0026] In an implementation manner, the tower base structure of the first textured region comprises a convex boss type structure or a recessed groove type structure, and the tower base structure of the second textured region comprises a convex boss type structure or a recessed groove type structure.

[0027] In the above technical solution, the tower base structure with the convex structure or the concave groove structure can further increase the roughness of the side surface where the first textured area and the second textured area are located, thereby reducing the reflectivity of the side surface where the first textured area and the second textured area are located, and further improving the utilization rate of the solar cell to light.

[0028] In an implementation, the solar cell includes opposite first and second chamfers. The side surface of the first chamfer includes a first area.

[0029] In an implementation, the first chamfer is smaller than the second chamfer.

[0030] In the above technical solution, the first and second chamfers can reduce or avoid damage of external stress to the corner of the solar cell, reduce or eliminate the probability of damage of the solar cell due to corner drop, and ensure the quality of the solar cell.

[0031] In an implementation, the solar cell further includes a passivation layer including a portion located on the side surface.

[0032] In an implementation, the passivation layer further includes a portion located on the first surface and the second surface; the first surface is a light-receiving surface, and the average thickness of the passivation layer located on the side surface is smaller than the average thickness of the passivation layer located on the first surface.

[0033] In an implementation, the solar cell further includes a passivation layer including a first passivation layer and a second passivation layer; the first passivation layer includes a portion located on the first surface or the second surface, and the second passivation layer includes a portion located on the cut side surface; the average thickness of the second passivation layer located on the cut side surface is greater than the average thickness of the first passivation layer located on the first surface or the second surface.

[0034] In an implementation, the second passivation layer further includes a portion located on the first surface and close to the edge of the cut side surface, and the portion of the second passivation layer located on the edge of the first surface is located above the first passivation layer; and / or,

[0035] The second passivation layer further includes a portion located on the second surface and close to the edge of the cut side surface, and the portion of the second passivation layer located on the edge of the second surface is located above the first passivation layer.

[0036] In an implementation, the average thickness of the second passivation layer on the cutting side surface is greater than or equal to 10 nm and less than or equal to 120 nm; and / or, the average thickness of the second passivation layer on the edge of the first surface is less than the average thickness of the second passivation layer on the cutting side surface; and / or, the average thickness of the second passivation layer on the edge of the second surface is less than the average thickness of the second passivation layer on the cutting side surface.

[0037] In an implementation, the coverage of the passivation layer on the first region is less than the coverage of the passivation layer on regions other than the first region in the side surface; and / or, the coverage of the passivation layer on the first region is greater than 80%.

[0038] In a second aspect, the present application provides a method for manufacturing a solar cell. The method comprises:

[0039] First, a semiconductor substrate is provided, which includes a first surface and a second surface opposite to each other;

[0040] Next, a first laser process is used to treat the first surface to form a groove as a guide groove on the first surface; the groove extends along a first direction;

[0041] Next, a second laser process is used to heat treat a portion of the first surface located in the middle of the guide groove along the first direction to form a heat treatment path;

[0042] Next, the semiconductor substrate is divided into at least two split semiconductor substrates along the heat treatment path;

[0043] Next, the cutting surface of the split semiconductor substrate is subjected to damage cleaning; the cutting surface includes at least one first region; the at least one first region includes a plurality of molten silicon regions and a first textured region located between the at least two molten silicon regions.

[0044] In the case of using the above technical solution, the damage cleaning is performed on the cutting surface of the split semiconductor substrate, and at this time, the laser damage layer generated by the first laser process can be removed to reduce the lattice defects.

[0045] In actual production of solar cells, the side surface of the split semiconductor substrate generally includes a "non-cutting surface" which is not cut and a "cutting surface" formed after cutting. The non-cutting surface is generally not attached with silicon slag and silicon oxide, or even if attached, the amount is so small that it can be ignored. Therefore, the analysis focuses on the silicon slag and silicon oxide on the cutting surface. An important source of the silicon slag and silicon oxide is that the silicon substrate of the solar cell is irradiated by a lossy laser during cutting of the cell, and the silicon substrate is melted and oxidized to form the silicon slag and silicon oxide after absorbing the laser energy. The part of the silicon slag and silicon oxide remaining after treatment is the molten silicon area in the present application. In the split semiconductor substrate provided in the present application, the cutting surface includes a first region, which is a laser cutting groove region (laser loss cutting region), and at least two molten silicon areas in the first region include a first texture region. Compared with the prior art in which the laser cutting groove region on the cutting surface is full of silicon slag and silicon oxide, the relative area of the molten silicon area in the present application is controlled to be within a reasonable range. Furthermore, the molten silicon area also includes a first texture region. The side surface of the first texture region and the molten silicon area can improve the light trapping effect of the side surface of the solar cell and increase the light absorption rate. Further, the relatively regular morphology of the first texture region can improve the film formation quality of the passivation layer, thereby improving the passivation effect.

[0046] In an implementation manner, after the cutting surface of the split semiconductor substrate is subjected to damage cleaning, the method for manufacturing the solar cell further includes: forming a passivation layer on at least the cutting surface of the split semiconductor substrate.

[0047] In the case of adopting the technical solution, the passivation effect of the solar cell can be improved to improve the photoelectric conversion efficiency of the solar cell. In addition, due to the formation of the passivation layer on the cutting surface of the split semiconductor substrate after cleaning, the surface dangling bonds generated due to the direct exposure of the cutting surface of the split semiconductor substrate to the air can be saturated under the action of the passivation layer. Based on this, the minority carrier lifetime of the cutting surface can be improved to reduce the recombination current, thereby improving the conversion efficiency of the solar cell and the module power.

[0048] In an implementation manner, the groove includes a first portion, a second portion and a third portion; a first end of the first portion and a first end of the second portion are connected to one end of the third portion; the distance between the first portion and the second portion gradually increases in a direction away from the third portion; and a second end of the first portion and a second end of the second portion are close to the edge of the semiconductor substrate.

[0049] In the technical solution, the split semiconductor substrate formed by splitting along the heat treatment path has a chamfer, compared with the case where the angle of the split semiconductor substrate cutting side is a right angle, external stress can be reduced or avoided to damage the corner of the split semiconductor substrate, the probability of damage of the split semiconductor substrate due to corner drop can be reduced or eliminated, so as to ensure the quality of the split semiconductor substrate, and further ensure the quality of the solar cell.

[0050] In an implementation manner, the included angle between the first part and the third part is equal to the included angle between the second part and the third part.

[0051] In an implementation manner, the ratio of the depth of the groove to the thickness of the semiconductor substrate is greater than or equal to 30% and less than or equal to 100%, and the depth direction of the groove is consistent with the thickness direction of the semiconductor substrate.

[0052] In the technical solution, when the ratio is greater than or equal to 30% or the ratio is equal to 100%, the first region formed as a guide region can effectively split the whole semiconductor substrate into two split semiconductor substrates. Further, when the ratio is less than 100%, the damage of the semiconductor substrate by the lossy laser can be reduced.

[0053] And / or, the second laser process adopts a non-lossy thermal laser.

[0054] In the technical solution, the non-lossy thermal laser is used to heat treat the part of the whole semiconductor substrate located in the middle of the guide groove, so that the damage to the semiconductor substrate can be reduced.

[0055] In a third aspect, the application further provides a photovoltaic module. The photovoltaic module comprises:

[0056] A plurality of solar cells as described in the first aspect, or a plurality of solar cells prepared by the preparation method of the solar cell as described in the second aspect; an encapsulation layer covering the surface of the plurality of solar cells; and a cover plate covering the surface of the encapsulation layer away from the solar cells. BRIEF DESCRIPTION OF DRAWINGS

[0057] The accompanying drawings, which are included to provide a further understanding of the application, constitute a part of the application and serve to explain the application together with the specification, and do not limit the application in any way. In the drawings:

[0058] FIG. 1 is a schematic view of a part of the cutting side surface of the solar cell when the ratio of the width of the first region to the thickness of the solar cell is less than 100% in the embodiment of the application;

[0059] Fig. 2 is a structure diagram of a partial cut side surface of a solar cell when the ratio of the width of the first region to the thickness of the solar cell is equal to 100% in the embodiment of the present application;

[0060] Fig. 3 is a SEM diagram of a partial cut side surface when the ratio of the width of the first region to the thickness of the solar cell is equal to 100% in the embodiment of the present application;

[0061] Fig. 4 is a SEM diagram of other regions of a cut side surface when the ratio of the width of the first region to the thickness of the solar cell is equal to 100% in the embodiment of the present application;

[0062] Fig. 5 is a schematic diagram of the relationship between light and a solar cell in the embodiment of the present application;

[0063] Fig. 6 is a SEM diagram of a second textured region being a tower base structure in the embodiment of the present application;

[0064] Fig. 7 is a top view of a solar cell in the embodiment of the present application;

[0065] Fig. 8 is a schematic diagram of the relationship between a semiconductor substrate, a groove and a heat treatment path in the embodiment of the present application;

[0066] Fig. 9 is a top view of a groove in the embodiment of the present application;

[0067] Fig. 10 is a SEM diagram of a partial cut surface of a diced semiconductor substrate after the semiconductor substrate is processed by a lossy laser in the embodiment of the present application;

[0068] Fig. 11 is a SEM diagram of a partial cut surface of a diced semiconductor substrate after the semiconductor substrate is processed by a lossless heat laser in the embodiment of the present application.

[0069] Reference signs: 1-side surface, 2-first region, 20-melted silicon region, 21-first textured region, 22-groove structure, 3-second region, 4-first chamfer, 5-second chamfer, 6-solar cell, 7-semiconductor substrate, 70-diced semiconductor substrate, 8-groove, 80-first part, 81-second part, 82-third part. DETAILED DESCRIPTION

[0070] In order to make the technical problems to be solved, technical solutions and beneficial effects of the present application more clearly understood, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0071] It should be noted that when an element is referred to as being "fixed" or "set" on another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or indirectly connected to the other element.

[0072] In addition, the terms "first", "second", "third", "fourth" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", "third", "fourth" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0073] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0074] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0075] In a first aspect, the embodiments of the present application provide a solar cell. Referring to FIGS. 1-5, the above-mentioned solar cell includes opposite first and second surfaces, and a side surface 1 connecting the first and second surfaces. The side surface 1 includes at least one first region 2, the at least one first region 2 including a plurality of molten silicon regions 20 and a first textured region 21 between the at least two molten silicon regions 20.

[0076] The solar cell can include a semiconductor substrate. For example, the semiconductor substrate can be a silicon substrate. The solar cell can be an intrinsic conductive substrate, an N-type conductive substrate or a P-type conductive substrate. Preferably, the semiconductor substrate is an N-type conductive substrate or a P-type conductive substrate. Compared with the intrinsic conductive substrate, the N-type conductive substrate or the P-type conductive substrate has higher conductivity, which is conducive to reducing the series resistance of the solar cell and improving the efficiency of the solar cell. In terms of structure, the first surface of the solar cell can be a textured surface to improve the light trapping effect of the light surface of the solar cell, thereby improving the utilization rate of light of the solar cell. Of course, the first surface of the solar cell can also be a flat surface. As for the second surface of the solar cell, it can be a polished surface or a textured surface, which is not limited here.

[0077] In actual production of the solar cell, the side surface of the solar cell generally includes a "non-cutting side surface" that is not cut and a "cutting side surface" formed after cutting. The non-cutting side surface is generally not attached with silicon slag and silicon oxide, or even if it is attached, the amount is very small and can be ignored. Therefore, the analysis here focuses on the silicon slag and silicon oxide on the cutting side surface, and an important source of the silicon slag and silicon oxide is that the silicon substrate of the solar cell is irradiated by a lossy laser during cutting of the cell piece, and the silicon substrate is melted and oxidized after absorbing laser energy.

[0078] The number of the first regions can be determined according to actual conditions, for example, it can be one, two, three, four or more. Further, the position of the first region on the side surface of the solar cell can also be set according to actual conditions, for example, the upper right corner region, the lower right corner region, the upper left corner region, the lower left corner region, the upper middle region, the lower middle region, the left side region, the right side region, the middle region, etc. of the cutting side surface included in the side surface, which depends on the specific way of dividing, for example, laser grooving from the light surface or the back surface of the solar cell, and the depth of the laser grooving.

[0079] Generally, by cutting the whole solar cell according to the division number N, N divided solar cells can be obtained, and the division number N can be any positive integer greater than or equal to 2.

[0080] The following describes three possible cases, and it should be understood that the following description is only for understanding and is not used for specific limitation.

[0081] Example one: when cutting a whole solar cell, if there is only one cutting side surface (i.e. a whole solar cell is divided into two split solar cells along its length direction), and a non-through guide groove is opened by laser at both ends of the first surface of the whole solar cell. At this time, the side surface (or cutting side surface) includes two first regions, which are respectively located in the right upper corner region and the left upper corner region of the cutting side surface. Of course, a guide groove can also be opened by laser from the second surface of the solar cell opposite to the first surface, at this time, the two first regions are respectively located in the right lower corner region and the left lower corner region of the cutting side surface. That is, the solar cell can open the guide groove from the light side, or from the back light side.

[0082] Example two: when cutting a whole solar cell, if there are two cutting side surfaces (i.e. a whole solar cell is divided into three split solar cells along its length direction), and a non-through guide groove is opened by laser at both ends of the first surface of the whole solar cell. At this time, the side surface of the middle split solar cell includes four first regions, wherein the four first regions are respectively located in the right upper corner region and the left upper corner region of the two cutting side surfaces.

[0083] Example three: when cutting a whole solar cell, if there are two cutting side surfaces (i.e. a whole solar cell is divided into three split solar cells along its length direction), and a non-through guide groove is opened by laser at both ends of the first surface of the whole solar cell. Further, a guide groove is added at the middle position of one of the cutting side surfaces, at this time, the side surface of the middle split solar cell includes five first regions. Among them, for the first cutting side surface, two first regions are respectively located in the right upper corner region and the left upper corner region of the first cutting side surface. For the second cutting side surface, three first regions are respectively located in the right upper corner region, the left upper corner region and the middle upper region of the second cutting side surface.

[0084] Referring to FIGS. 1-3, in the solar cell provided by the embodiments of the present application, the cutting side surface includes a first region 2, which is a laser opening guide groove region (laser loss cutting region), and at least two molten silicon regions 20 in the first region 2 include a first texture region 21. In comparison with the prior art in which the laser opening guide groove region on the cutting surface is entirely silicon slag and silicon oxide, the embodiments of the present application control the area and distribution form of the molten silicon region 20 on the cutting side surface, so that the relative area of the molten silicon region 20 is within a reasonable range. Moreover, the molten silicon region 20 further includes the first texture region 21. The side surface of the first texture region 21 and the molten silicon region can improve the light trapping effect of the side surface 1 of the solar cell and increase the light absorption rate. Further, the relatively regular form of the first texture region 21 can improve the film forming quality of the passivation layer and thus improve the passivation effect.

[0085] From the material aspect, the molten silicon region 20 includes silicon and silicon oxide.

[0086] As a possible implementation, referring to FIG. 1, in the first region 2, the ratio of the total area of the molten silicon region 20 to the total area of the first texture region 21 is greater than or equal to 30% and less than or equal to 120%. For example, the ratio of the total area of the molten silicon region 20 to the total area of the first texture region 21 can be 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, or 120%, etc.

[0087] The ratio of the total area of the molten silicon region 20 to the total area of the first texture region 21 within the above range not only can reduce the complexity of the manufacturing process caused by pursuing too small total area of the molten silicon region 20, but also can ensure the utilization rate of light by the side surface 1 of the solar cell and optimize the overall passivation effect of the first region, so as to improve the photoelectric conversion efficiency of the solar cell.

[0088] In an optional manner, the plurality of molten silicon regions 20 are distributed in a scattered manner in the first region.

[0089] In an optional manner, the distribution range of the maximum width of the molten silicon region 20 is wide, that is, there are both small molten silicon regions and large molten silicon regions. The maximum width of a single molten silicon region 20 is preferably less than 100 microns, and the average maximum width of the molten silicon regions 20 in the first region 2 is preferably greater than or equal to 10 microns and less than or equal to 80 microns. For example, the average maximum width can be 10 microns, 20 microns, 50 microns, 60 microns, 70 microns, or 80 microns, etc. The maximum width of the molten silicon region is the maximum line segment length passing through the molten silicon region 20.

[0090] Referring to FIGS. 1-5, in the embodiments of the present application, the plurality of molten silicon regions are distributed in the first region in the form of isolated islands. The plurality of island-distributed molten silicon regions are beneficial to reflect more light to the first textured region through the sidewalls thereof, thereby improving the light trapping effect of the cut side surface of the solar cell, increasing the light absorption rate, and increasing the utilization rate of the side surface of the solar cell to light, thereby improving the photoelectric conversion efficiency of the solar cell. Preferably, the projection of the molten silicon region in the first region is an irregular polygon, and is uniformly distributed in the first region.

[0091] Referring to FIG. 5, according to the foregoing description, the solar cell includes opposite first and second surfaces. When the first surface S1 is a light-receiving surface and the second surface is a back surface, in order to better utilize light, the incident angle of the first surface of the solar cell is as close to 0° as possible. However, at this time, the incident angle of the incident light on the side surface is large, for example, close to 90°, thereby resulting in a low utilization rate of the side surface to light. In the embodiments of the present application, the first region includes a plurality of molten silicon regions and a first textured region between the molten silicon regions, the projection of the molten silicon region in the first region is in the shape of a polygonal irregular shape, and is distributed in the form of isolated islands and is uniformly distributed. At this time, it is beneficial to improve the utilization rate of the side surface of the solar cell to light. For example, in FIG. 5, after the incident light L1 and L2 pass through the molten silicon region, more light can be reflected to the first textured region, thereby improving the utilization rate of the side surface of the solar cell to light. Further, the maximum width of a single molten silicon region 20 is preferably less than 100 microns, and the average maximum width of the molten silicon region 20 in the first region 2 is preferably greater than or equal to 10 microns and less than or equal to 80 microns, which can balance the absorption and light trapping effect of light.

[0092] Preferably, the thickness of the molten silicon region on the side surface is greater than or equal to 1 micron and less than or equal to 50 microns. The thickness of the molten silicon region is the height difference between the top surface of the molten silicon region and the first textured region. For example, the thickness of the molten silicon region on the side surface can be 1 micron, 5 microns, 10 microns, 15 microns, 20 microns, 25 microns, 30 microns, 35 microns, 40 microns, 45 microns, or 50 microns, etc.

[0093] Further, the first region includes micro-cracks, i.e. groove structures 22, which extend in any one or more of a dendritic shape, a straight line shape, a zigzag shape, a curved shape, etc. As shown in FIG. 3 and FIG. 5, the groove structures 22 facilitate the light to penetrate deeper into the side surface of the solar cell and into the silicon substrate, thereby improving the utilization of the light. Preferably, the depth of the groove structure is 1-10 microns, and the cross section of the groove structure is any one or more of a V shape and a U shape. The bottom and the sidewall of the groove structure can be a relatively flat planar structure or a textured structure. For example, the depth of the groove structure can be 1 micron, 2 microns, 3 microns, 4 microns, 5 microns, 6 microns, 7 microns, 8 microns, 9 microns or 10 microns, etc.

[0094] Further, the molten silicon region can include a multi-layer structure arranged in layers, and the edges of each layer of the molten silicon region are irregular. The multi-layer structure arranged in layers facilitates the scattering of light at the edges of the molten silicon region. In addition, the molten silicon region includes a porous structure, which further facilitates the utilization of light.

[0095] As a possible implementation, referring to FIG. 1, the ratio of the width W of the first region 2 to the thickness D of the solar cell is greater than or equal to 30% and less than or equal to 100%; the width direction of the first region 2 and the thickness direction of the solar cell are both consistent with the direction from the first surface to the second surface. For example, the ratio of the width of the first region to the thickness of the solar cell can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100%, etc.

[0096] In the case of using the above technical solution, when the ratio is greater than or equal to 30% or the ratio is equal to 100%, it can be ensured that the first region formed as a guide region effectively divides the whole solar cell into two partial solar cells. Further, when the ratio is less than 100%, the damage of the solar cell caused by the lossy laser can be reduced.

[0097] For example, referring to FIG. 1, FIG. 1 is a structure diagram of partially cutting the side surface when the ratio of the width W of the first region 2 to the thickness D of the solar cell is less than 100%.

[0098] Referring to FIG. 2, FIG. 2 is a structure diagram of partially cutting the side surface when the ratio of the width W of the first region 2 to the thickness D of the solar cell is equal to 100%. FIG. 3 is a SEM diagram of partially cutting the side surface when the ratio of the width of the first region 2 to the thickness of the solar cell is equal to 100%. FIG. 4 is a SEM diagram of other regions of the cut side surface when the ratio of the width of the first region to the thickness of the solar cell is equal to 100%.

[0099] As a possible implementation, referring to FIG. 1, the side surface 1 further comprises a second region 3, and the second region 3 comprises a second textured area, which is beneficial to improve the light trapping effect of the second region 3. In addition, in the process of manufacturing the solar cell, a passivation layer will be formed on the second region 3 of the side surface 1 of the solar cell, and the texture structure of the second textured area is beneficial to the passivation effect, so as to improve the photoelectric conversion efficiency of the solar cell.

[0100] In combination with the foregoing description, the side surface comprises a cut side surface and a non-cut side surface. The first region is located on the cut side surface; and the second region is located on the cut side surface and / or the non-cut side surface.

[0101] For example, the first region and the second region are both located on the cut side surface of the solar cell. Or, the second region is located on the non-cut side surface of the solar cell, and the first region is located on the cut side surface of the solar cell. Or, the first region is located on the cut side surface of the solar cell, and the second region is located on the non-cut side surface and the cut side surface of the solar cell.

[0102] Referring to FIG. 1, when the first region 2 and the second region 3 are both located on the cut side surface of the solar cell, the cut side surface comprises a molten silicon area 20, a first textured area 21 and a second textured area. Compared with the case that the laser guide groove area on the cut surface in the prior art is all silicon slag and silicon oxide, in the embodiment of the present application, the relative area of the side molten silicon area is controlled within a reasonable range by controlling the area and distribution form of the molten silicon area on the cut side surface. In addition, the first textured area is further comprised between the molten silicon areas, and the cut side surface further comprises the second textured area. The first textured area and the second textured area can improve the light trapping effect of the side surface of the solar cell and increase the light absorption rate. Further, the relatively regular form of the first textured area and the second textured area can improve the film forming quality of the passivation layer, thereby improving the passivation effect.

[0103] The structure comprised by the first textured area and the structure comprised by the second textured area can be the same or different. Further, the structure comprised by the first textured area and the structure comprised by the second textured area can be a velvet structure or a tower base structure. The following will be described by taking two possible cases as examples, and it should be understood that the following description is only for understanding and is not used for specific definition.

[0104] Firstly, the first textured area comprises a velvet structure, and the second textured area comprises a velvet structure (for example, the structure shown in FIG. 4), and the velvet structure comprised by the first textured area and the velvet structure comprised by the second textured area both comprise a pyramid structure.

[0105] In the technical solution, when the first and second textured regions have pyramid structures, the specific surface area of the side surface where the first and second textured regions are located can be increased, so that the side surface where the first and second textured regions are located has a good light trapping effect, and the utilization rate of the solar cell to light is further improved.

[0106] Further, the average height of the pyramid structure of the first textured region is less than the average height of the pyramid structure of the second textured region, or the average base width of the pyramid structure of the first textured region is less than the average base width of the pyramid structure of the second textured region. At this time, it is beneficial to form a passivation layer on the first textured region later to improve the passivation effect of the solar cell, and further improve the photoelectric conversion efficiency of the solar cell.

[0107] The second kind: the first textured region includes a tower base structure, and the second textured region includes a tower base structure (for example, the structure shown in FIG. 6). The tower base transverse dimension of the tower base structure of the first textured region is less than the tower base transverse dimension of the tower base structure of the second textured region. At this time, it is beneficial to form a passivation layer on the first textured region later to improve the passivation effect of the solar cell, and further improve the photoelectric conversion efficiency of the solar cell. It should be noted that when the top view of the tower base is a quadrilateral, the tower base transverse dimension can be the length of any side or diagonal of the quadrilateral.

[0108] In an optional manner, the tower base structure of the first textured region includes a convex boss structure or a recessed groove structure, and the tower base structure of the second textured region includes a convex boss structure or a recessed groove structure.

[0109] The tower base structure of the convex boss structure or the recessed groove structure can further increase the roughness of the side surface where the first and second textured regions are located, and thus beneficially reduce the reflectivity of the side surface where the first and second textured regions are located, to further improve the utilization rate of the solar cell to light.

[0110] As a possible implementation manner, referring to FIG. 7, the solar cell 6 includes opposite first and second chamfers 4 and 5. The side surface of the first chamfer 4 includes the first region 2, and the first chamfer 4 is smaller than the second chamfer 5. The first and second chamfers 4 and 5 can reduce or avoid damage of external stress to the corner of the solar cell, reduce or eliminate the probability of damage of the solar cell due to corner falling, to ensure the quality of the solar cell.

[0111] For example, the solar cell 6 generally includes two first chamfers 4 and two second chamfers 5, the two first chamfers 4 are close to the cut side surface, the two second chamfers 5 are close to the surface opposite to the cut side surface, and the first chamfer 4 is smaller than the second chamfer 5.

[0112] In one implementation, the above solar cell further comprises a passivation layer, which can be located on the cut side surface, the non-cut side surface, the first surface and the second surface. The following description is given by way of example in several possible cases, it should be understood that the following description is only for understanding, not for specific definition.

[0113] Example one: the passivation layer is on the side surface of the solar cell, including the cut side surface and the non-cut side surface.

[0114] Example two: the passivation layer is on the side surface of the solar cell, including the cut side surface and the non-cut side surface, the first surface and the second surface, and is formed in the same process. That is, the passivation layer on the side surface is integrally formed and continuously distributed with the passivation layer on the first surface and the passivation layer on the second surface. When the first surface is the light-receiving surface and the second surface is the back surface, the passivation layer on the second surface can be located only in a certain range of the edge of the second surface, for example, within 5 microns of the edge of the second surface, while the average thickness of the passivation layer located on the side surface is less than the average thickness of the passivation layer located on the first surface. The passivation layer preferably includes at least one of aluminum oxide, silicon oxide and silicon nitride.

[0115] Example three: the passivation layer of the above solar cell comprises a first passivation layer and a second passivation layer. The first passivation layer includes a portion located on the first surface or the second surface, and the second passivation layer includes a portion located on the cut side surface, and the average thickness of the second passivation layer located on the cut side surface is greater than the average thickness of the first passivation layer located on the first surface or the second surface.

[0116] Example four: the passivation layer of the above solar cell comprises a first passivation layer and a second passivation layer. The first passivation layer includes a portion located on the first surface and / or the second surface, and the second passivation layer includes a portion located on the cut side surface, and the average thickness of the second passivation layer located on the cut side surface is greater than the average thickness of the first passivation layer located on the first surface or the second surface. The second passivation layer further includes a portion located on the first surface and close to the edge of the cut side surface, and the portion of the second passivation layer located on the edge of the first surface is located above the first passivation layer; and / or, the second passivation layer further includes a portion located on the second surface and close to the edge of the cut side surface, and the portion of the second passivation layer located on the edge of the second surface is located above the first passivation layer.

[0117] For example, the passivation layer of the solar cell includes a first passivation layer and a second passivation layer. The first passivation layer includes a portion on the first surface and / or the second surface; the second passivation layer includes a portion on the cut side surface and a portion on the first surface and / or the second surface within a certain range close to the edge of the cut side surface; and the second passivation layer covers the first passivation layer within the certain range on the first surface and / or the second surface close to the edge of the cut side surface, so as to realize the laminated structure of the first passivation layer and the second passivation layer. The first passivation layer and the second passivation layer can be formed in different process steps. Since the cut side surface includes the first region with the molten silicon area, the second passivation layer covering the cut side surface can be formed in a separate step, so that the passivation requirement of the first region can be better met. Preferably, the average thickness of the second passivation layer on the cut side surface is greater than the average thickness of the first passivation layer on the first surface or the second surface. The average thickness of the second passivation layer on the cut side surface is greater than or equal to 10 nm and less than or equal to 120 nm. For example, the average thickness of the second passivation layer on the cut side surface can be 10 nm, 30 nm, 50 nm, 80 nm, 90 nm, 100 nm or 120 nm, etc. The material of the first passivation layer and the second passivation layer can be selected from the group consisting of aluminum oxide, silicon oxide and silicon nitride, and can include at least one of aluminum oxide, silicon oxide and silicon nitride; the material and structure of the first passivation layer can be the same as or different from those of the second passivation layer; and the first passivation layer and the second passivation layer can be a single-layer film or a laminated structure of multiple-layer films. Further, the average thickness of the second passivation layer on the edge of the first surface is less than the average thickness of the second passivation layer on the cut side surface; and / or, the average thickness of the second passivation layer on the edge of the second surface is less than the average thickness of the second passivation layer on the cut side surface.

[0118] As a possible implementation, regarding the passivation layer formed at different positions, the coverage of the passivation layer on the first region is less than that on the region other than the first region in the side surface of the solar cell; or the coverage of the passivation layer on the first region 2 is less than that on the second region 3 in the cut side surface. Since the first region has the molten silicon area and the surface structure thereof is more complex than that of the second region 3, the overall coverage of the passivation layer on the first region is less than that on the second region after the passivation layer is formed. Preferably, the coverage of the passivation layer on the first region 2 is greater than 80%, so as to ensure the overall passivation effect of the first region and avoid other problems caused by excessive setting of the passivation layer, such as increase of process time and material.

[0119] In a second aspect, the embodiments of the present application further provide a preparation method of a solar cell. Referring to FIGS. 8 to 11, the preparation method of the solar cell includes:

[0120] First, a semiconductor substrate 7 is provided, the semiconductor substrate 7 comprising opposite first and second surfaces.

[0121] Exemplarily, the semiconductor substrate can be a silicon substrate. In terms of conductive type, the semiconductor substrate can be an intrinsic conductive substrate, an N-type conductive substrate or a P-type conductive substrate. Preferably, the semiconductor substrate is an N-type conductive substrate or a P-type conductive substrate. Compared with the intrinsic conductive substrate, the N-type conductive substrate or the P-type conductive substrate has higher conductivity, which is conducive to reducing the series resistance of the solar cell and improving the efficiency of the solar cell.

[0122] Next, the semiconductor substrate is cut into pieces. For example, by cutting the whole semiconductor substrate into pieces according to a division number N, N pieces of semiconductor substrates can be obtained, wherein the division number N can be any positive integer greater than or equal to 2. A first laser process is performed on the first surface to form a groove 8 on the first surface, the groove 8 extending along a first direction;

[0123] Exemplarily, the first laser process adopts a lossy laser. The groove formed on the semiconductor substrate by the lossy laser serves as a guide groove, which is conducive to the subsequent separation of the piece of semiconductor substrate along the guide groove to ensure that the shape of the piece of semiconductor substrate meets the actual requirements.

[0124] In an example, the ratio of the depth of the groove to the thickness of the semiconductor substrate is greater than or equal to 30% and less than or equal to 100%, and the depth direction of the groove is consistent with the thickness direction of the semiconductor substrate. For example, the ratio can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100%, etc.

[0125] In the case of using the above technical solution, when the ratio is greater than or equal to 30% or the ratio is equal to 100%, the first region formed as a guide region can effectively separate the whole semiconductor substrate into two pieces of semiconductor substrates. Further, when the ratio is less than 100%, the damage of the lossy laser to the semiconductor substrate can be reduced.

[0126] Further, referring to Fig. 9, as an alternative, the groove 8 comprises a first portion 80, a second portion 81 and a third portion 82, the first end of the first portion 80 and the first end of the second portion 81 are connected to one end of the third portion 82. The distance between the first portion 80 and the second portion 81 gradually increases in the direction away from the third portion 82, and the second end of the first portion 80 and the second end of the second portion 81 are close to the edge of the semiconductor substrate 7. Exemplarily, the groove can be a Y-shaped groove. In this case, the length direction of the third portion 82 in the groove 8 is the extension direction of the groove, i.e. the first direction.

[0127] In the case of adopting the technical scheme, the split semiconductor substrate formed by splitting along the heat treatment path has a chamfer, compared to the case that at least two corners of the split semiconductor substrate are right angles, the damage of external stress to the corner of the split semiconductor substrate can be reduced or avoided, the probability of damage of the split semiconductor substrate due to corner drop can be reduced or eliminated, so as to ensure the quality of the split semiconductor substrate, and further ensure the quality of the solar cell.

[0128] As a possible implementation, referring to Fig. 9, the included angle A between the first portion 80 and the third portion 82 is equal to the included angle B between the second portion 81 and the third portion 82. As for the size of the two included angles, it can be set according to actual conditions, which is not limited here.

[0129] Next, a second laser process is used to heat treat the first surface in the first direction to form a heat treatment path L;

[0130] Exemplarily, the second laser process uses a lossless thermal intense laser. Using a lossless thermal intense laser to heat treat the part of the whole semiconductor substrate located in the guide groove can reduce the damage to the semiconductor substrate.

[0131] Next, the semiconductor substrate 7 is split into at least two split semiconductor substrates 70 along the heat treatment path L;

[0132] Exemplarily, after the heat treatment path and the two grooves are formed on the first surface of the semiconductor substrate, water is sprayed on the semiconductor substrate, at this time the semiconductor substrate naturally cracks to form at least two split semiconductor substrates. Referring to Fig. 10, Fig. 10 shows the appearance of part of the cutting surface of the split semiconductor substrate after the semiconductor substrate is treated by a lossy laser. It can be observed that there is silicon slag and silicon oxide in Fig. 10. Referring to Fig. 11, Fig. 11 shows the appearance of part of the cutting surface of the split semiconductor substrate after the semiconductor substrate is treated by a lossless thermal intense laser. It can be observed that there is no silicon slag and silicon oxide on the cutting surface in Fig. 11.

[0133] Next, the cutting surface of the diced semiconductor substrate is subjected to damage cleaning, at which time the laser damage layer resulting from the first laser process cutting can be removed to reduce lattice defects.

[0134] For example, in a chain cleaning machine, the diced semiconductor substrate is placed in an HF and HNO3 tank, and subjected to cleaning in a roller liquid or water floating mode to remove part of the silicon slag and silicon oxide on the cutting surface of the diced semiconductor substrate. Since the cutting surface is not protected by the phosphosilicate glass layer, the concentration of HF and HNO3 is increased to increase the corrosion of the cutting surface, thereby increasing the cleaning of the cutting surface, making the cutting surface smoother than the cutting surface in the prior art, and making the cleaning effect of the cutting surface similar to the cleaning effect of the other surfaces of the diced semiconductor substrate. Then, the alkali texturing and additive ratio adjustment are performed when passing through the tank cleaner, and the cutting surface is subjected to texturing and corrosion, so that the effects of the texturing on each surface of the diced semiconductor substrate are similar, thereby improving the passivation effect of the solar cell after forming a passivation layer on the diced semiconductor substrate.

[0135] The cutting surface includes at least one first region, and the at least one first region includes a plurality of molten silicon regions and a first textured region between the at least two molten silicon regions. The number and position of the first region can be referred to the description of the first aspect, which will not be repeated here.

[0136] In actual production of solar cells, the side surface of the diced semiconductor substrate generally includes a "non-cutting surface" (i.e. the "non-cutting side surface" described in the first aspect) that is not cut and a "cutting surface" (i.e. the "cutting side surface" described in the first aspect) formed after cutting. The non-cutting surface is generally not attached with silicon slag and silicon oxide, and even if it is attached, the amount is negligible. Therefore, the analysis here focuses on the silicon slag and silicon oxide on the cutting surface, which is an important source of the silicon slag and silicon oxide formed by irradiating the silicon substrate of the solar cell with a lossy laser during cutting of the cell. The part of the silicon slag and silicon oxide that remains after processing is the molten silicon region in the present application. In the diced semiconductor substrate provided in the present application, the cutting surface includes a first region, which is a laser cutting guide groove region (laser loss cutting region), and the first region includes a first textured region between the at least two molten silicon regions. Compared to the case where the laser cutting guide groove region on the cutting surface is entirely covered with silicon slag and silicon oxide in the prior art, the relative area of the molten silicon region in the present application is controlled to be within a reasonable range, and the first region further includes a first textured region. The side surface of the first textured region 21 and the molten silicon region can improve the light trapping effect of the side surface 1 of the solar cell, increase the light absorption rate, and the relatively regular shape of the first textured region 21 can improve the film formation quality of the passivation layer, thereby improving the passivation effect.

[0137] In an alternative, the ratio of the total area of the molten silicon regions to the total area of the first textured region in the first region is greater than or equal to 30% and less than or equal to 120%. For example, the ratio of the total area of the molten silicon regions to the total area of the first textured region can be 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 110%, or 120%, etc.

[0138] The ratio of the total area of the molten silicon regions 20 to the total area of the first textured region 21 in the above range not only can reduce the complexity of the manufacturing process caused by pursuing too small total area of the molten silicon regions 20, but also can ensure the utilization of the light by the side surface 1 of the solar cell and optimize the overall passivation effect of the first region to improve the photoelectric conversion efficiency of the solar cell. The plurality of molten silicon regions are distributed in the first region in the form of isolated islands. The plurality of island-distributed molten silicon regions are conducive to reflecting more light to the first textured region through the sidewalls thereof, thereby improving the light trapping effect of the cut surface of the solar cell, increasing the light absorption rate, and improving the utilization of the light by the side surface of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell. Preferably, the projection of the molten silicon regions in the first region is an irregular polygon and is uniformly distributed in the first region.

[0139] As a possible implementation, the cut surface further comprises a third region, and the third region comprises a third textured region, which is conducive to improving the light trapping effect and passivation effect of the third region.

[0140] The structure included in the first textured region and the structure included in the third textured region can be the same or different. Further, the structure included in the first textured region and the structure included in the third textured region can be a velvet structure or a tower base structure. The following describes two possible cases, and it should be understood that the following description is only for understanding and is not used for specific definition.

[0141] Example one: the first textured region includes a velvet structure, the third textured region includes a velvet structure, and the velvet structure included in the first textured region and the velvet structure included in the third textured region each includes a pyramid structure.

[0142] In the case of using the above technical solution, when the velvet structure on the first textured region and the third textured region is a pyramid structure, it is conducive to increasing the specific surface area of the cut surface. Based on this, it is conducive to making the cut surface have a good light trapping effect and further improving the utilization of the light by the solar cell.

[0143] Since the first region includes a plurality of molten silicon regions, when wet processing is performed, the first textured region in the first region grows for a shorter time than the third textured region in the third region. Therefore, the average height of the pyramid structures of the first textured region is smaller than the average height of the pyramid structures of the third textured region, or the average base width of the pyramid structures of the first textured region is smaller than the average base width of the pyramid structures of the third textured region.

[0144] Secondly, the first textured region includes a tower base structure, and the third textured region includes a tower base structure. The tower base lateral dimension of the tower base structure of the first textured region is smaller than the tower base lateral dimension of the tower base structure of the third textured region. It should be noted that when the top view of the tower base is a quadrilateral, the tower base lateral dimension can be the length of any side or diagonal of the quadrilateral.

[0145] In an alternative, the tower base structure of the first textured region includes a boss type structure or a recessed groove type structure, and the tower base structure of the third textured region includes a boss type structure or a recessed groove type structure.

[0146] Compared with the tower base structure forming a flat surface, the tower base structure of the boss type structure or the recessed groove type structure can further increase the roughness of the cutting surface, thereby facilitating the reduction of the reflectivity of the cutting surface, so as to further improve the utilization rate of the solar cell to the light.

[0147] It should be understood that the semiconductor substrate further includes a side surface connecting the first surface and the second surface. According to the final result of the cutting, the side surface includes a cutting surface and a non-cutting surface. The description of the cutting surface can be referred to the foregoing, and will not be repeated here. The non-cutting surface can include a fourth textured region, and the fourth textured region can include a textured structure and a tower base structure. The textured structure can include a pyramid structure, and the tower base structure can include a boss type structure or a recessed groove type structure. The sizes of the textured structure and the tower base structure of the third textured region and the textured structure and the tower base structure of the fourth textured region can be the same or different. The sizes of the textured structure and the tower base structure of the fourth textured region are generally larger than the sizes of the textured structure and the tower base structure of the first textured region.

[0148] After the damage cleaning of the cutting surface of the diced semiconductor substrate, the method for manufacturing the solar cell further includes: forming a passivation layer on at least the cutting surface of the diced semiconductor substrate.

[0149] At this time, the passivation of the solar cell can be improved, so as to improve the photoelectric conversion efficiency of the solar cell. In addition, since the passivation layer is formed on the cutting surface of the diced semiconductor substrate after the cleaning, the surface dangling bonds generated due to the direct exposure of the cutting surface of the diced semiconductor substrate to the air can be saturated under the action of the passivation layer. Based on this, the minority carrier lifetime of the cutting surface can be improved, so as to reduce the recombination current, thereby improving the conversion efficiency of the solar cell and the module power.

[0150] In an optional manner, the passivation layer comprises a multi-layer structure arranged in a stack, such as a stack of aluminum oxide and silicon nitride, and is arranged on the cutting surface of the semiconductor substrate to improve the protection of the cutting surface.

[0151] In the case of the above technical solution, the aluminum oxide passivation layer and the silicon nitride passivation layer arranged in a stack can passivate the cutting surface, reduce the recombination rate of carriers at the cutting surface, and further improve the photoelectric conversion efficiency of the solar cell. Further, the silicon nitride passivation layer can reduce reflection, which is conducive to allowing more light to be refracted from the cutting surface into the semiconductor substrate to further improve the utilization rate of light by the solar cell.

[0152] The following describes the position of the "cutting and slicing" step described above in the manufacturing process of two types of solar cells. It should be understood that the following description is for understanding only and is not used to specifically limit.

[0153] The first type is for a TOPCon cell. The manufacturing process of the TOPCon cell includes:

[0154] S1, providing a semiconductor substrate;

[0155] S2, cleaning and texturing the semiconductor substrate;

[0156] S3, performing boron diffusion treatment and etching treatment on the textured semiconductor substrate to form a PN junction on the light-receiving side of the semiconductor substrate;

[0157] S4, polishing the back surface of the semiconductor substrate to remove the diffusion layer on the back surface of the semiconductor substrate;

[0158] S5, sequentially forming a tunneling oxide layer and a doped polysilicon layer on the back surface of the semiconductor substrate;

[0159] S6, cleaning the semiconductor substrate to remove the PSG layer around the light-receiving surface and side surface of the semiconductor substrate, and to remove the BSG layer on the light-receiving surface and the PSG layer on the back surface;

[0160] S7, forming a passivation and anti-reflection layer on the surface of the structure formed in the above steps.

[0161] The step of "singulating the wafer" described above can be located anywhere between S1 and S6, for example, after S1, before S2, or after S2, before S3, or after S3, before S4, or after S4, before S5, or after S5, before S6; after the step of singulating the wafer, the solar cell of the first aspect of the present application can be obtained by controlling the cleaning solution, process parameters, etc. in the step of S6. In the present embodiment, it is preferred that the first texturing region comprises a tower base structure, and the second texturing region comprises a tower base structure; in another case, the semiconductor substrate provided in the step of S1 is a pre-singulated semiconductor substrate, for example, the semiconductor substrate has been singulated before entering the solar cell production process.

[0162] The second type is for BC solar cells. The first type of BC solar cell is produced by the following steps:

[0163] S1, providing a semiconductor substrate, the semiconductor substrate comprising a first surface and a second surface;

[0164] S2, cleaning the semiconductor substrate;

[0165] S3, forming a first doped semiconductor material layer on the second surface;

[0166] S4, patterning the first doped semiconductor material layer to form a first doped semiconductor layer on a part of the second surface;

[0167] S5, forming a second doped semiconductor material layer on the second surface;

[0168] S6, patterning the second doped semiconductor material layer so that the first doped semiconductor layer and the second doped semiconductor layer are arranged alternately and spaced apart;

[0169] S7, cleaning and / or texturing the semiconductor substrate;

[0170] S8, forming a passivation anti-reflection layer on the first surface of the semiconductor substrate, the first doped semiconductor material layer and the second doped semiconductor material layer.

[0171] The step of "singulation" described above can be located at any position between S1 and S7, for example, after S1, before S2, or after S2, before S3, or after S3, before S4, or after S4, before S5, or after S5, before S6, or after S5, before S6, or after S6, before S7; after the step of singulation, the liquid, process parameters, etc. in step S7 can be controlled to obtain the solar cell of the first aspect of the present application. In addition, in another case, the semiconductor substrate provided in the step S1 is a pre-singulated semiconductor substrate, for example, it has been singulated before entering the cell production process.

[0172] The second BC cell manufacturing process includes:

[0173] S1, providing a semiconductor substrate, the semiconductor substrate including opposite first and second surfaces;

[0174] S2, cleaning the semiconductor substrate;

[0175] S3, forming a first doped semiconductor material layer on the second surface;

[0176] S4, patterning the first doped semiconductor material layer to form a first doped semiconductor layer on a portion of the semiconductor substrate;

[0177] S5, cleaning and / or texturing the semiconductor substrate;

[0178] S6, forming a passivation anti-reflection layer on the first surface of the semiconductor substrate, the first doped semiconductor material layer, and the second surface of the semiconductor substrate exposed to the area outside the first doped semiconductor layer.

[0179] The step of "singulation" described above can be located at any position between S1 and S5, for example, after S1, before S2, or after S2, before S3, or after S3, before S4, or after S4, before S5; after the step of singulation, the liquid, process parameters, etc. in step S5 can be controlled to obtain the solar cell of the first aspect of the present application. In addition, in another case, the semiconductor substrate provided in the step S1 is a pre-singulated semiconductor substrate, for example, it has been singulated before entering the cell production process.

[0180] In a third aspect, the embodiments of the present application also provide a photovoltaic module. The photovoltaic module includes: a plurality of solar cells as described in the first aspect, or prepared by the second aspect; and a packaging layer covering the surface of the plurality of solar cells; and a cover plate covering the surface of the packaging layer away from the solar cells.

[0181] In the description of the above-mentioned embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0182] The above description is merely illustrative of the application and is not intended to limit the scope of the application. Any changes or modifications that can be made to the application in accordance with the principle of the application should be encompassed within the scope of the application. Therefore, the scope of the application should be determined by the scope of the claims.

Claims

1. A solar cell, comprising opposite first and second surfaces, and a side surface connecting the first and second surfaces; the side surface comprises at least one first region; at least one of the first regions comprises a plurality of fused silicon regions, and a first textured region between at least two of the fused silicon regions.

2. The solar cell of claim 1, wherein, In the first region, a ratio of a total area of the fused silicon regions to a total area of the first textured region is greater than or equal to 30% and less than or equal to 120%.

3. The solar cell of claim 1, wherein, The plurality of fused silicon regions are distributed in the first region in an island-like manner; and / or, a maximum width of the fused silicon regions is less than 100 microns.

4. The solar cell of claim 1, wherein, A ratio of a width of the first region to a thickness of the solar cell is greater than or equal to 30% and less than or equal to 100%; the width of the first region and the thickness of the solar cell are both in a direction from the first surface to the second surface.

5. The solar cell of claim 1, wherein, The first region comprises a trench structure.

6. The solar cell of claim 5, wherein, The trench structure extends in any one or more of a dendritic, linear, zigzag, and curved manner; and / or, a depth of the trench structure is 1-10 microns; and / or, a cross-section of the trench structure is any one or more of V-shaped and U-shaped.

7. The solar cell of claim 1, wherein, The fused silicon region comprises a multi-layer structure arranged in a stack; and / or, the fused silicon region comprises a porous structure; and / or, the fused silicon region comprises an oxide of silicon.

8. The solar cell according to any one of claims 1 to 7, wherein, The side surface further comprises a second region, the second region comprising a second textured region.

9. The solar cell of claim 8, wherein, The side surface comprises a cut side surface and a non-cut side surface; The first region is located at the cut side surface; The second region is located at the cut side surface and / or the non-cut side surface.

10. The solar cell of claim 8, wherein, The first textured region comprises a textured structure, and the second textured region comprises a textured structure; the textured structure of the first textured region and the textured structure of the second textured region each comprise a pyramid structure; an average height of the pyramid structure of the first textured region is less than an average height of the pyramid structure of the second textured region, or an average base width of the pyramid structure of the first textured region is less than an average base width of the pyramid structure of the second textured region.

11. The solar cell of claim 8, wherein, The first textured region comprises a tower base structure, and the second textured region comprises a tower base structure; a tower base lateral dimension of the tower base structure of the first textured region is less than a tower base lateral dimension of the tower base structure of the second textured region.

12. The solar cell of claim 11, wherein, The tower base structure of the first textured region comprises a boss-type structure or a recessed groove-like structure; The tower base structure of the second textured region comprises a boss-type structure or a recessed groove-like structure.

13. The solar cell of any of claims 1-7, wherein, The solar cell comprises opposite first and second chamfers; a side surface of the first chamfer comprises the first region.

14. The solar cell of claim 13, wherein, The first chamfer is smaller than the second chamfer.

15. The solar cell of any of claims 1-7, wherein, The solar cell further comprises a passivation layer, the passivation layer comprising a portion located at the side surface.

16. The solar cell of claim 15, wherein, The passivation layer further comprises a portion located at the first and second surfaces; the first surface is a light-receiving surface, and an average thickness of the passivation layer located at the side surface is less than an average thickness of the passivation layer located at the first surface.

17. The solar cell of claim 9, wherein, The solar cell further includes a passivation layer, the passivation layer includes a first passivation layer and a second passivation layer; the first passivation layer includes a portion located on the first surface or the second surface, and the second passivation layer includes a portion located on the cut side surface, the average thickness of the second passivation layer located on the cut side surface is greater than the average thickness of the first passivation layer located on the first surface or the second surface.

18. The solar cell of claim 17, the second passivation layer further includes a portion located on the first surface near an edge of the cut side surface, and the portion of the second passivation layer located on the edge of the first surface is located above the first passivation layer; and / or, The second passivation layer further includes a portion located on the second surface near an edge of the cut side surface, and the portion of the second passivation layer located on the edge of the second surface is located above the first passivation layer.

19. The solar cell of claim 18, the average thickness of the second passivation layer located on the cut side surface is greater than or equal to 10 nanometers and less than or equal to 120 nanometers; and / or, the average thickness of the second passivation layer located on the edge of the first surface is less than the average thickness of the second passivation layer located on the cut side surface; and / or, the average thickness of the second passivation layer located on the edge of the second surface is less than the average thickness of the second passivation layer located on the cut side surface.

20. The solar cell of claim 15, the coverage of the passivation layer on the first region is less than the coverage on a region other than the first region in the side surface; and / or, the coverage of the passivation layer on the first region is greater than 80%.

21. A method for manufacturing a solar cell, comprising: providing a semiconductor substrate, the semiconductor substrate including opposite first and second surfaces; treating the first surface with a first laser process to form a groove as a guide groove on the first surface, the groove extending along a first direction; treating a portion of the first surface located in the middle of the guide groove along the first direction with a second laser process to form a heat treatment path; splitting the semiconductor substrate along the heat treatment path into at least two split semiconductor substrates; damaging and cleaning the cut surface of the split semiconductor substrate; the cut surface includes at least one first region; the at least one first region includes a plurality of molten silicon regions and a first textured region located between at least two of the molten silicon regions.

22. The method of producing a solar cell according to claim 21, wherein After damaging and cleaning the cut surface of the split semiconductor substrate, the method for manufacturing a solar cell further comprises: forming a passivation layer on at least the cut surface of the split semiconductor substrate.

23. The method of producing a solar cell according to claim 21, wherein The groove includes a first portion, a second portion, and a third portion; each of the first portion and the second portion has a first end away from an edge of the semiconductor substrate and a second end close to the edge of the semiconductor substrate, and the first end of the first portion and the first end of the second portion are connected to one end of the third portion; The distance between the first portion and the second portion gradually increases in a direction away from the third portion; An included angle between the first portion and the third portion is equal to an included angle between the second portion and the third portion.

24. The method of producing a solar cell according to claim 21, wherein A ratio of a depth of the groove to a thickness of the semiconductor substrate is greater than or equal to 30% and less than or equal to 100%, a depth direction of the groove is consistent with a thickness direction of the semiconductor substrate; And / or; the second laser process employs a lossy heat intense laser.

25. A photovoltaic module, comprising: a plurality of solar cells as claimed in any one of claims 1-20, or a plurality of solar cells prepared by the method as claimed in any one of claims 21-24; an encapsulation layer covering surfaces of the plurality of solar cells; a cover plate covering surfaces of the encapsulation layer away from the solar cells.

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