Solar cell and photovoltaic module

Abstract

The present application relates to the technical field of solar cells. Disclosed are a solar cell and a photovoltaic module, so as to solve the problem of different regions of a cut face of a shingled solar cell varying significantly in terms of morphology, leading to a reduction in the efficiency of the solar cell. The solar cell comprises a first face and a second face opposite each other, and a side surface connecting the first face and the second face. The side face comprises: a cut face, the cut face comprising a cut edge adjacent to the first face and a fractured edge adjacent to the second face; and a first passivation layer formed on the cut face, the first passivation layer comprising an aluminum oxide passivation layer. The cut face comprises a first region adjacent to the cut edge and a second region farther away from the cut edge than the first region, with the ratio of oxygen to aluminum in at least part of the first region being greater than the ratio of oxygen to aluminum in at least part of the second region.

Description

Solar cell and photovoltaic module

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and benefits of Chinese patent application No. 202411404868.8, filed on October 10, 2024, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present application relates to the technical field of solar cells, and in particular to a solar cell and a photovoltaic module. Background Art

[0004] A solar cell is a device that utilizes solar energy, directly converting light energy into electrical energy through the photoelectric or photochemical effects. Solar cells include slicing solar cells. Currently, slicing solar cells typically involves cutting a solar cell that has already been formed with multiple film layers into at least two slicing solar cells, such as two halves. These slicing solar cells are then used to make photovoltaic modules.

[0005] However, after cutting, the morphologies of different regions of the cut surface of the sliced ​​solar cell vary greatly, resulting in reduced efficiency of the solar cell. Summary of the Invention

[0006] The purpose of this application is to provide a solar cell and a photovoltaic module for improving the efficiency of the solar cell.

[0007] To achieve the above objectives, in a first aspect, the present application provides a solar cell. The solar cell includes 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 includes a cut surface, the cut surface including a cut edge adjacent to the first surface and a fracture edge adjacent to the second surface. A first passivation layer is formed on the cut surface, the first passivation layer including an aluminum oxide passivation layer. The cut surface includes a first region adjacent to the cut edge and a second region further away from the cut edge than the first region, wherein the ratio of oxygen to aluminum in at least a portion of the first region is greater than the ratio of oxygen to aluminum in at least a portion of the second region.

[0008] Since the first area close to the cutting edge is the area that is most affected by direct external forces, it has a more complex composition and surface morphology. For example, the morphology of silicon other than single crystal silicon includes irregularly arranged amorphous morphologies, which often contain a large number of defects and dangling bonds, and the complex surface morphology exacerbates the formation of defects. Therefore, the presence of more oxygen elements can fully react this part of silicon and eliminate the adverse effects it brings. Compared with the first area, the second area is not directly affected by external forces or the direct external forces are weaker, and is basically a single crystal silicon morphology with a complete crystal structure. The introduction of too much oxygen may bring more surface defects. Therefore, the ratio of oxygen elements to aluminum elements in at least part of the first area is set to be greater than the ratio of oxygen elements to aluminum elements in at least part of the second area to balance the impact of the difference in surface morphology between the first area and the second area, thereby improving the overall efficiency of the solar cell.

[0009] In one implementation, the cutting surface includes a first trench structure and a crack structure, the first trench structure is located in the first region, and the thickness of the first passivation layer is greater than the depth of the first trench structure and less than the depth of the crack structure.

[0010] When the above technical solution is adopted, since a first passivation layer is formed on the cut surface, the first passivation layer can passivate the cut surface, reduce the recombination rate of photogenerated carriers at the cut surface, and improve the photoelectric conversion efficiency of the solar cell. Furthermore, since the first groove structure is densely distributed and complex in structure, and sometimes contains non-single-crystal silicon components of silicon, resulting in complex surface morphology and composition in this area, and a high density of surface recombination centers, the thickness of the first passivation layer is set to be greater than the depth of the first groove structure. At this time, the first passivation layer can completely fill the first groove structure to maximize passivation repair and improve the conversion efficiency of the solar cell. Furthermore, since the crack structure is mostly formed by natural fracture under stress, its surface is relatively smooth. Setting the thickness of the first passivation layer to be less than the depth of the crack structure is sufficient to perform limited passivation on the area. At the same time, the first passivation layer formed on the cut surface is in an undulating state, which can enhance the light trapping effect of the cut surface and increase the concentration of photogenerated carriers on the cut surface, thereby improving the utilization rate of light on the cut surface of the solar cell, and further improving the photoelectric conversion efficiency of the solar cell. In one implementation, the depth of the first trench structure is less than 1.2 μm. This can reduce the degree of damage to the solar cell caused by the first trench structure, thereby ensuring that no cracks are caused or excessive defects are introduced during subsequent production.

[0011] In one implementation, the depth of the crack structure is greater than or equal to 1 μm, which can ensure uniform coating and light trapping during the passivation process.

[0012] In one implementation, the thickness of the first passivation layer is greater than or equal to 30 nm and less than or equal to 200 nm. When the above technical solution is adopted, the passivation effect of the solar cell gradually increases, and the conversion efficiency of the solar cell increases with the increase in the thickness of the first passivation layer.

[0013] In one implementation, the difference between the aluminum content in at least a portion of the second region and the aluminum content in at least a portion of the first region is greater than 3%.

[0014] When the above technical solution is adopted, it can be ensured that different passivation surfaces (ie different areas) achieve the required passivation effects.

[0015] In one implementation, the first groove structure is adjacent to the cutting edge, and the first groove structure includes an end portion extending from the cutting edge toward the breaking edge, and the end portion boundary of the first groove structure is wavy or sawtooth-shaped.

[0016] When the above technical solution is adopted, it is possible to avoid excessive stress concentration on the cut surface of the solar cell and improve the quality of the cut surface.

[0017] In one implementation, the cutting surface includes an edge area and a middle area, the edge area is adjacent to the cutting edge or the broken edge, and the middle area is located in the middle part of the cutting surface; the roughness of the first passivation layer located in the middle area is less than the roughness of the first passivation layer located in the edge area.

[0018] When the above technical solution is adopted, the escape of sunlight can be avoided as much as possible and the passivation effect can be guaranteed.

[0019] In one implementation, the distance between the wave crests of the wave shape or sawtooth shape is greater than or equal to 3 um and less than or equal to 20 um.

[0020] When the above technical solution is adopted, since the spacing between the wave peaks is greater than or equal to 3 μm, the first groove structure can be prevented from being too concentrated, thereby preventing excessive stress concentration on the cut surface of the solar cell and improving the quality of the cut surface.

[0021] In one implementation, an angle is formed between an extension direction of the crack structure and an extension direction of the first groove structure, and the angle is greater than or equal to 45° and less than 90°.

[0022] In one implementation, within the cutting plane, an extension length of the first trench structure is greater than or equal to 1 um and less than or equal to 20 um.

[0023] When the above technical solution is adopted, the damage caused by cracks to the silicon wafer can be reduced.

[0024] In one implementation, the first surface includes a second groove structure, and the second groove structure is adjacent to the cutting edge.

[0025] In one implementation, along a direction away from the cutting edge, an extension length of the second trench structure is greater than or equal to 20 um and less than or equal to 100 um.

[0026] In one implementation, the solar cell further includes: a second passivation layer formed in an edge region of the first surface, the edge region of the first surface is close to the cut surface, and the second passivation layer is continuously distributed with the first passivation layer.

[0027] When using the above technical solution, the second passivation layer can passivate the edge area of ​​the first surface near the cut surface, reducing the carrier recombination rate at the first surface and improving the photoelectric conversion efficiency of the solar cell. Furthermore, when the second passivation layer covers the second trench structure, the second passivation layer can passivate and repair the second trench structure to improve the conversion efficiency of the solar cell.

[0028] In one implementation, along a direction from an edge of the first surface to a central region of the first surface, a width of the second passivation layer is greater than an extension length of the second trench structure.

[0029] In one implementation, along a direction from an edge of the first surface to a central area of ​​the first surface, a width of the second passivation layer is greater than or equal to 0.05 mm and less than or equal to 2 mm.

[0030] In one implementation, the thickness of the first passivation layer is greater than the thickness of the second passivation layer.

[0031] In one implementation, the thickness of the second passivation layer gradually decreases along a direction from the edge of the first surface to the central area of ​​the first surface.

[0032] In one implementation, the thickness of the second passivation layer is greater than or equal to 30 nm and less than or equal to 200 nm.

[0033] In one implementation, the first surface is a light-facing surface or a backlight surface.

[0034] In a second aspect, the present application further provides a photovoltaic module, which includes the solar cell described in the first aspect.

[0035] Compared with the prior art, the beneficial effects of the photovoltaic module provided in this application are the same as the beneficial effects of the solar cell described in the above technical solution, and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0037] FIG1 is a SEM image of a cut surface in an embodiment of the present application;

[0038] FIG2 is a schematic structural diagram of a solar cell having a first passivation layer, a second passivation layer, and a third passivation layer formed therein according to an embodiment of the present application;

[0039] FIG3 is a SEM image of a first passivation layer formed on a cut surface in an embodiment of the present application.

[0040] Reference numerals: 1 - cutting surface, 11 - edge region, 12 - middle region, 2 - first trench structure, 3 - crack structure, 4 - first passivation layer, 5 - second passivation layer. DETAILED DESCRIPTION

[0041] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is 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 this application and are not intended to limit this application.

[0042] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may 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 may be directly connected to the other element or indirectly connected to the other element.

[0043] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" means two or more, unless otherwise clearly and specifically defined. "Several" means one or more, unless otherwise clearly and specifically defined.

[0044] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on this application.

[0045] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0046] In order to solve the above technical problems, in the first aspect, the present application provides a solar cell. Referring to Figures 1 and 2, the above solar cell includes a first surface and a second surface relative to each other, and a side surface connecting the first surface and the second surface. The side surface includes a cutting surface 1, and the cutting surface 1 includes a relative cutting edge and a breaking edge. In the cell slicing process, the first surface of the cell is damaged to a certain extent by direct external action, so that the cell can be broken or the cell is guided to break. For example, the first surface is first damaged by mechanical cutting or laser irradiation, and then the entire solar cell is broken by stress changes, thereby forming a complete cutting surface 1. Among them, the cutting edge is the first surface of the cutting surface 1 adjacent to the cell that is directly affected by the outside, and the breaking edge is adjacent to the second surface.

[0047] A first passivation layer 4 is formed on the cutting surface 1, the first passivation layer comprising an aluminum oxide passivation layer. The cutting surface comprises a first region and a second region, the first region being adjacent to the cutting edge and the second region being further away from the cutting edge than the first region, and the ratio of oxygen to aluminum in at least a portion of the first region being greater than the ratio of oxygen to aluminum in at least a portion of the second region.

[0048] Since the first area close to the cutting edge is the area that is most affected by direct external forces, it has a more complex composition and surface morphology. For example, the morphology of silicon other than single crystal silicon includes irregularly arranged amorphous morphologies, which often contain a large number of defects and dangling bonds, and the complex surface morphology exacerbates the formation of defects. Therefore, the presence of more oxygen elements can fully react this part of silicon and eliminate the adverse effects it brings. Compared with the first area, the second area is not directly affected by external forces or the direct external forces are weaker, and is basically a single crystal silicon morphology with a complete crystal structure. The introduction of too much oxygen may bring more surface defects. Therefore, the ratio of oxygen elements to aluminum elements in at least part of the first area is set to be greater than the ratio of oxygen elements to aluminum elements in at least part of the second area to balance the impact of the difference in surface morphology between the first area and the second area, thereby improving the overall efficiency of the solar cell.

[0049] As one possible implementation, the first region is defined as the area extending 30 μm from the cut edge toward the fracture edge, and the second region is defined as the area outside the first region. When the first region is defined as the area extending 30 μm from the cut edge toward the fracture edge, the area directly affected by external forces is limited, resulting in a more balanced stress on the cut surface of the solar cell and a reduced risk of PV module package cracking. This passivation method effectively repairs the cut fractures, ensuring a successful repair.

[0050] The aluminum content in at least a portion of the first region is less than the aluminum content in at least a portion of the second region. For example, the difference between the aluminum content in at least a portion of the second region and the aluminum content in at least a portion of the first region is greater than 3%. In this case, the desired passivation effect can be achieved on different passivation surfaces (i.e., different regions).

[0051] In one embodiment, the aluminum content in at least a portion of the first region is greater than or equal to 1% and less than or equal to 3%. For example, the aluminum content in at least a portion of the first region may be 1%, 1.5%, 2%, 2.5%, 2.8%, or 3%. The aluminum content in at least a portion of the second region is greater than or equal to 4% and less than or equal to 7%. For example, the aluminum content in at least a portion of the second region may be 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, or 7%.

[0052] Table 1 The proportion of different elements in the first area and the second area

[0053] As can be seen from Table 1, the ratio of oxygen to aluminum in the first region is greater than 3, while the ratio of oxygen to aluminum in the second region is less than 3. For example, when the thickness of the aluminum oxide passivation layer is less than 50 nm, the ratio of oxygen to aluminum in the first region is greater than or equal to 5, such as 5, 6, 7, 8, or 9. When the thickness of the aluminum oxide passivation layer is greater than 50 nm, the ratio of oxygen to aluminum in the first region is greater than or equal to 3 and less than or equal to 8, such as 3, 4, 5, 6, 7, or 8.

[0054] The above-mentioned solar cell includes a semiconductor substrate. Exemplarily, the above-mentioned semiconductor substrate can be a silicon substrate. In terms of conductivity type, 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 a higher conductivity, which is beneficial to reduce the series resistance of the solar cell and improve the efficiency of the solar cell. From a structural point of view, the first side of the solar cell can be a velvet surface to improve the light trapping effect of the solar cell to the light surface, thereby improving the utilization rate of light by the solar cell. Of course, the first side of the solar cell can also be a flat polished surface. As for the second side of the solar cell, it can be a polished surface or a velvet surface, which is not specifically limited here.

[0055] In another aspect of the present application, the cut surface includes a first trench structure 2 and a crack structure 3; the first trench structure 2 is located in the first region; the thickness of the first passivation layer 4 is greater than the depth of the first trench structure 2 and less than the depth of the crack structure 3. Exemplarily, the crack structure substantially runs through the entire cut surface, extending from the cut edge to the fracture edge.

[0056] Referring to Figures 1 and 2, in the solar cell provided by the embodiment of the present application, since a first passivation layer 4 is formed on the cut surface, the first passivation layer 4 can passivate the cut surface 1, reduce the recombination rate of photogenerated carriers at the cut surface, and improve the photoelectric conversion efficiency of the solar cell. Furthermore, since the first groove structure is densely distributed and complex in structure, and sometimes contains non-single-crystal silicon components of silicon, resulting in complex surface morphology and composition in this area and a high density of surface recombination centers, the thickness of the first passivation layer 4 is set to be greater than the depth of the first groove structure 2. At this time, the first passivation layer 4 can completely fill the first groove structure 2 to maximize the passivation repair and improve the conversion efficiency of the solar cell. Furthermore, since the crack structure 3 is mostly formed by natural fracture under stress, its surface is relatively smooth. Setting the thickness of the first passivation layer 4 to be less than the depth of the crack structure 3 is sufficient to perform limited passivation on this area. At the same time, the first passivation layer 4 formed on the cut surface 1 is in an undulating state, which can enhance the light trapping effect of the cut surface 1 and increase the concentration of photogenerated carriers on the cut surface 1, thereby improving the utilization rate of light by the cut surface 1 of the solar cell, thereby further improving the photoelectric conversion efficiency of the solar cell. In addition, since the overall surface of the crack structure 3 is relatively smooth and regular, the crack structure 3 is conducive to light absorption.

[0057] As a possible implementation, the thickness of the first passivation layer being greater than the depth of the first trench structure and less than the depth of the crack structure can be understood as meaning that the average thickness of the first passivation layer is greater than the maximum depth of the first trench structure and less than the minimum depth of the crack structure. Alternatively, the average thickness of the first passivation layer is greater than the average depth of the first trench structure and less than the average depth of the crack structure.

[0058] As a possible implementation, the thickness of the first passivation layer is greater than or equal to 30 nm and less than or equal to 200 nm. For example, the thickness of the first passivation layer can be 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, 145 nm, 150 nm, 155 nm, 160 nm, 165 nm, 170 nm, 175 nm, 180 nm, 185 nm, 190 nm, 195 nm, or 200 nm. When the above technical solution is adopted, the passivation effect of the solar cell gradually increases, and the conversion efficiency of the solar cell increases with the increase of the thickness of the first passivation layer. Furthermore, a passivation layer that is too thin will result in insufficient passivation effect, while a passivation layer that is too thick will reduce the marginal effect of the passivation effect and increase the process time and material consumption.

[0059] The following describes relevant parameters of solar cells using first passivation layers of different thicknesses as an example.

[0060] Table 2 Related parameters of solar cells

[0061] Here, BSL represents the control group, 30nm-BSL represents the difference between the 30nm-thick first passivation layer and the control group, Eta represents the conversion efficiency, Isc represents the short-circuit current, Voc represents the open-circuit voltage, and FF represents the fill factor.

[0062] As a possible implementation, referring to Figures 1 and 3 , the cut surface 1 includes an edge region 11 and a middle region 12. The edge region 11 is adjacent to the cut edge or fracture edge, and the middle region 12 is located in the middle portion of the cut surface 1. The roughness of the first passivation layer 4 in the middle region 12 is less than that of the first passivation layer 4 in the edge region 11. In this manner, the escape of sunlight can be minimized while maintaining the passivation effect.

[0063] As a possible implementation, the first groove structure extends for a length greater than or equal to 1 μm and less than or equal to 20 μm within the cut surface, away from the cutting edge. Controlling the overall distribution of the first groove structure ensures efficient cell cutting without introducing excessive defects on the cut surface. For example, the first groove structure can extend for a length of 1 μm, 3 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, or 20 μm.

[0064] As a possible implementation, the depth of the first trench structure is less than 1.2 μm. In this case, the degree of damage to the solar cell caused by the first trench structure can be reduced, thereby ensuring that no cracks are caused and no excessive defects are introduced during post-production.

[0065] As a possible implementation method, referring to Figure 1, the first groove structure 2 is distributed in the first area, the first groove structure 2 is adjacent to the cutting edge, the first groove structure 2 extends from the cutting edge to the breaking edge, the first groove structure 2 includes an end extending from the cutting edge to the breaking edge, and the end boundary M of the first groove structure 2 is wavy or sawtooth.

[0066] In this case, excessive stress concentration on the cut surface of the solar cell can be avoided, thereby improving the quality of the cut surface. It should be noted that the first groove end boundary is the boundary away from the cut edge.

[0067] As a possible implementation method, the depth of the crack structure is greater than or equal to 1 μm and the surface is smooth, which can ensure the uniformity of the coating and the light trapping effect during the passivation process.

[0068] As a possible implementation method, the depth of the crack structure located in the area where the first groove structure is located is greater than or equal to 1um and less than or equal to 2um; illustratively, the depth of the above crack structure can be 1um, 1.2um, 1.5um, 1.7um, 1.9um or 2um, etc.

[0069] The depth of the crack structure away from the area where the first groove structure is located is greater than or equal to 1um and less than or equal to 2um. Exemplarily, the depth of the crack structure can be 1um, 1.2um, 1.5um, 1.7um, 1.9um or 2um.

[0070] As a possible implementation, referring to FIG1 , the first groove structure 2 can be distributed in any of a dendritic, bifurcated, or curved manner, thereby avoiding excessive stress concentration on the cut surface of the solar cell and improving the quality of the cut surface.

[0071] In one optional embodiment, referring to FIG1 , the horizontal spacing L between the wave-shaped or sawtooth-shaped peaks is greater than or equal to 3 μm and less than or equal to 20 μm. For example, the horizontal spacing L can be 3 μm, 5 μm, 8 μm, 10 μm, 12 μm, 13 μm, 15 μm, 18 μm, 19 μm, or 20 μm. Since the spacing between the wave peaks is greater than or equal to 3 μm, the first groove structure can be prevented from being too concentrated, thereby preventing excessive stress concentration on the cut surface of the solar cell and improving the quality of the cut surface.

[0072] In one alternative embodiment, referring to FIG1 , an angle A is formed between the extension direction of the crack structure 3 and the extension direction of the first groove structure 2. The presence of angle A can guide the depth and width of the crack to be more uniform. Angle A is preferably greater than or equal to 45° and less than 90°. For example, angle A can be 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, or 89°, etc.

[0073] As a possible implementation manner, the first surface includes a second groove structure, and the second groove structure is adjacent to the cutting edge.

[0074] In one embodiment, the second groove structure extends for a length greater than or equal to 20 μm and less than or equal to 100 μm in a direction away from the cutting edge. For example, the length of the second groove structure may be 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, or 100 μm.

[0075] In an optional manner, referring to FIG. 2 , the solar cell further includes: a second passivation layer 5 formed in an edge region of the first surface, the edge region of the first surface being close to the cut surface, and the second passivation layer 5 and the first passivation layer 4 being continuously distributed.

[0076] When using the above technical solution, the second passivation layer can passivate the edge area of ​​the first surface near the cut surface, reducing the carrier recombination rate at the first surface and improving the photoelectric conversion efficiency of the solar cell. Furthermore, when the second passivation layer covers the second trench structure, the second passivation layer can passivate and repair the second trench structure to improve the conversion efficiency of the solar cell.

[0077] As a possible implementation, referring to FIG. 2 , along the direction from the edge of the first surface to the center region of the first surface, the width W of the second passivation layer 5 is greater than the extension length of the second trench structure.

[0078] As a possible implementation, referring to FIG2 , the width W of the second passivation layer 5 is greater than or equal to 0.05 mm and less than or equal to 2 mm. For example, the width W of the second passivation layer 5 can be 0.05 mm, 0.15 mm, 0.55 mm, 1 mm, 1.05 mm, 1.55 mm, or 2 mm. Preferably, the width W of the second passivation layer 5 is greater than or equal to 1 mm and less than or equal to 2 mm. For example, the width of the second passivation layer can be 1 mm, 1.05 mm, 1.35 mm, 1.55 mm, 1.85 mm, or 2 mm.

[0079] In an optional manner, the thickness of the first passivation layer is greater than the thickness of the second passivation layer.

[0080] In an optional manner, the thickness of the second passivation layer gradually decreases along a direction from the edge of the first surface to the central area of ​​the first surface.

[0081] In an optional embodiment, the thickness of the second passivation layer is greater than or equal to 30 nm and less than or equal to 200 nm along the direction from the edge of the first surface to the central area of ​​the first surface. Exemplarily, the thickness of the second passivation layer can be 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, 145 nm, 150 nm, 155 nm, 160 nm, 165 nm, 170 nm, 175 nm, 180 nm, 185 nm, 190 nm, 195 nm or 200 nm, etc.

[0082] As a possible implementation, the solar cell further includes: a third passivation layer formed in an edge region of the second surface, the edge region of the second surface being close to the cut surface, and the third passivation layer and the first passivation layer being continuously distributed.

[0083] When the above technical solution is adopted, the third passivation layer can passivate the edge area of ​​the second surface close to the cut surface, reduce the recombination rate of carriers at the second surface, and improve the photoelectric conversion efficiency of the solar cell.

[0084] As a possible implementation method, in addition to the first passivation layer, the second passivation layer and the third passivation layer, other passivation layers stacked on or under the first passivation layer, the second passivation layer or the third passivation layer may also be included, such as at least one of silicon oxide, silicon nitride and silicon oxynitride.

[0085] In one embodiment, the width of the third passivation layer along the direction from the edge of the second surface to the center area of ​​the second surface is greater than or equal to 20 μm and less than or equal to 100 μm. For example, the width of the third passivation layer can be 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, or 100 μm.

[0086] In an optional manner, the thickness of the first passivation layer is greater than the thickness of the third passivation layer.

[0087] In an optional manner, the thickness of the third passivation layer gradually decreases along a direction from the edge of the second surface to the central area of ​​the second surface.

[0088] In an optional embodiment, the thickness of the third passivation layer is greater than or equal to 30 nm and less than or equal to 200 nm along the direction from the edge of the second surface to the central area of ​​the second surface. Exemplarily, the thickness of the third passivation layer can be 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, 145 nm, 150 nm, 155 nm, 160 nm, 165 nm, 170 nm, 175 nm, 180 nm, 185 nm, 190 nm, 195 nm or 200 nm, etc.

[0089] In one optional embodiment, the first surface is a light-facing surface or a backlight-facing surface. The solar cell may be a bifacial solar cell or a back-contact solar cell. The solar cell may be a PERC cell, a TOPCON cell, a TBC cell, or a heterojunction solar cell. Of course, the solar cell may also include a tunneling passivation structure or other types of solar cells including a heterojunction structure.

[0090] In a second aspect, an embodiment of the present application further provides a photovoltaic assembly, which includes the solar cell described in the first aspect.

[0091] The photovoltaic assembly includes a cell string formed by interconnecting a plurality of solar cells, wherein the cell string includes a welding interconnection structure, such as a welding ribbon or welding wire, that electrically interconnects two adjacent solar cells. The welding interconnection structure has a head and a tail, and at least one of the head and tail of the welding interconnection structure is adjacent to a cut surface of the solar cell. For example, the two adjacent solar cells are a first solar cell and a second solar cell. The welding interconnection structure electrically interconnects the first and second adjacent solar cells, and the welding interconnection structure extends from a position near the cut surface of the first solar cell to a position near the cut surface of the second solar cell, or from a position near the cut surface of the first solar cell to a position near a side surface of the second solar cell opposite the cut surface, or from a position near the side surface of the first solar cell opposite the cut surface to a position near the cut surface of the second solar cell. Because the position and offset of the head and tail of the welding interconnection structure are difficult to control during the welding process, there is a certain probability that the passivation dielectric layer will be damaged or even punctured. The cell of the present application has a first passivation layer formed on the cut surface, and a second passivation layer is additionally formed in the edge regions of the first and second surfaces adjacent to the cut surface. This provides a relatively thick dielectric layer in the edge regions of the first and second surfaces, providing adequate protection for the edge regions of the cell and reducing the probability of the head and tail portions of the solder interconnect structure puncturing the passivation dielectric layer. Furthermore, at least one of the head and tail portions of the solder interconnect structure extends above the second passivation layer in the edge region of the first or second surface.

[0092] The beneficial effects of the photovoltaic module provided in the embodiment of the present application are the same as the beneficial effects of the solar cell described in the above technical solution, and will not be described in detail here.

[0093] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0094] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A solar cell, characterized in that: The solar cell includes 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 includes a cutting surface; the cutting surface includes a cutting edge adjacent to the first surface and a breaking edge adjacent to the second surface; forming a first passivation layer on the cutting surface; The first passivation layer comprises an aluminum oxide passivation layer; The cutting surface includes a first region adjacent to the cutting edge and a second region further away from the cutting edge than the first region; The ratio of oxygen to aluminum in at least a portion of the first region is greater than the ratio of oxygen to aluminum in at least a portion of the second region.

2. The solar cell according to claim 1, wherein The cutting surface includes a first groove structure and a crack structure; the first groove structure is located in the first region; the thickness of the first passivation layer is greater than the depth of the first groove structure and less than the depth of the crack structure.

3. The solar cell according to claim 2, wherein The depth of the first groove structure is less than 1.2 μm; or the depth of the crack structure is greater than or equal to 1 μm.

4. The solar cell according to claim 1 or 2, characterized in that The thickness of the first passivation layer is greater than or equal to 30 nm and less than or equal to 200 nm.

5. The solar cell according to claim 1, wherein A difference between the aluminum content in at least a portion of the second region and the aluminum content in at least a portion of the first region is greater than 3%.

6. The solar cell according to claim 2, wherein The first groove structure is adjacent to the cutting edge. The first groove structure includes an end portion extending from the cutting edge toward the breaking edge. The end portion boundary of the first groove structure is wavy or sawtooth-shaped.

7. The solar cell according to claim 1, wherein The cutting surface includes an edge area and a middle area, the edge area is adjacent to the cutting edge or the broken edge, and the middle area is located in the middle part of the cutting surface; the roughness of the first passivation layer located in the middle area is less than the roughness of the first passivation layer located in the edge area.

8. The solar cell according to claim 6, wherein The distance between the wave crests of the wave or sawtooth shape is greater than or equal to 3 μm and less than or equal to 20 μm.

9. The solar cell according to claim 6 or 8, characterized in that An angle is formed between an extension direction of the crack structure and an extension direction of the first groove structure, and the angle is greater than or equal to 45° and less than 90°.

10. The solar cell according to claim 6 or 8, characterized in that In the cutting plane, an extension length of the first groove structure is greater than or equal to 1 um and less than or equal to 20 um.

11. The solar cell according to any one of claims 1 to 3 and 5 to 8, characterized in that: The first side includes a second groove structure adjacent to the cutting edge.

12. The solar cell according to claim 11, characterized in that Along a direction away from the cutting edge, an extension length of the second groove structure is greater than or equal to 20 um and less than or equal to 100 um.

13. The solar cell according to claim 11, wherein The solar cell further includes: a second passivation layer formed in an edge region of the first surface, the edge region of the first surface being close to the cut surface; the second passivation layer and the first passivation layer being continuously distributed.

14. The solar cell according to claim 13, characterized in that Along a direction from an edge of the first surface to a central region of the first surface, a width of the second passivation layer is greater than an extension length of the second trench structure.

15. The solar cell according to claim 13, wherein Along a direction from an edge of the first surface to a central area of ​​the first surface, a width of the second passivation layer is greater than or equal to 0.05 mm and less than or equal to 2 mm.

16. The solar cell according to claim 13, wherein The thickness of the first passivation layer is greater than the thickness of the second passivation layer.

17. The solar cell according to claim 13, wherein The thickness of the second passivation layer gradually decreases along a direction from an edge of the first surface to a central area of ​​the first surface.

18. The solar cell according to claim 13, wherein The thickness of the second passivation layer is greater than or equal to 30 nm and less than or equal to 200 nm.

19. The solar cell according to any one of claims 1 to 3 and 5 to 8, characterized in that: The first surface is a light-facing surface or a backlight surface.

20. A photovoltaic module, characterized in that: The solar cell comprises the solar cell according to any one of claims 1 to 19.

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