Solar cells and solar modules
The solar cell design with passivation layers on the cut and edge regions addresses efficiency losses by reducing carrier recombination and enhancing photoelectric conversion efficiency through improved passivation and light confinement.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- LONGI PHOTOVOLTAIC TECHNOLOGY (ORDOS) CO LTD
- Filing Date
- 2025-11-28
- Publication Date
- 2026-04-22
AI Technical Summary
The efficiency of solar cells is reduced due to varying shapes and complex surface morphologies on the cut surfaces of cut solar cells, leading to increased defect formation and carrier recombination.
A solar cell design with a first passivation layer on the cut surface and a second passivation layer on the edge region, featuring groove and crack structures, to reduce carrier recombination and improve photoelectric conversion efficiency.
The passivation layers effectively reduce carrier recombination and enhance the photoelectric conversion efficiency of the solar cell by passivating the cut and edge regions, improving light confinement and reducing defects.
Smart Images
Figure 2026068733000001_ABST
Abstract
Description
Technical Field
[0001] (Cross - reference to related applications) This application claims the priority and benefits of a Chinese patent application with application number 202411404868.8, filed on October 10, 2024, the content of which is incorporated herein by reference.
[0002] This application relates to the technical field of solar cells, and particularly to solar cells and solar modules.
Background Art
[0003] A solar cell is a device that utilizes solar energy and directly converts light energy into electrical energy through the photovoltaic effect or the photochemical effect. Solar cells include cut solar cells. Currently, in the production of cut solar cells, usually, a cutting process is performed on a solar cell with multiple formed film layers to cut the entire solar cell into at least two cut solar cells, for example, two half - cut cells. Then, the cut solar cells are used in the production of solar modules.
[0004] However, after cutting, the shapes of different regions on the cut surface of the cut solar cell are significantly different, which reduces the efficiency of the solar cell.
Summary of the Invention
Problems to be Solved by the Invention
[0005] The purpose of this application is to provide a solar cell and a solar module for improving the efficiency of solar cells.
Means for Solving the Problems
[0006] To achieve the above objective, in a first embodiment, the present application provides a solar cell. The solar cell includes a first surface and a second surface facing each other, and a side surface connecting the first surface and the second surface, wherein the side surface includes a cut surface including a cutting edge adjacent to the first surface and a fracture edge adjacent to the second surface, the solar cell includes a first passivation layer formed on the cut surface, and a second passivation layer formed in the edge region of the first surface and continuously distributed with the first passivation layer, wherein the first passivation layer includes an aluminum oxide passivation layer, the cut surface includes a first groove structure and a crack structure, the first surface includes a second groove structure, the second groove structure is adjacent to the cutting edge, and the edge region of the first surface is close to the cut surface.
[0007] The first region near the cut edge is a region greatly affected by direct external forces, and therefore has complex components and surface morphology, such as silicon shapes other than single-crystal silicon. The silicon in this region contains irregularly arranged amorphous shapes, and in many cases there are a large number of defects and dangling bonds, and the complex surface morphology makes defect formation serious. Therefore, by providing a first passivation layer, passivation of the cut surface can be achieved, and the recombination of nearby carriers and defects can be reduced. In addition, because the second groove structure exists on the first surface, it itself creates defects on the first surface of the battery cell, and then carriers generated in the edge region near the cut surface inside the battery cell body move close to the cut surface and easily recombine with defects on it, resulting in efficiency loss, and therefore the edge region also requires better passivation. The second passivation layer passivates the edge region near the cut surface of the first surface, reduces the rate of carrier recombination on the first surface, and can improve the photoelectric conversion efficiency of the solar cell.
[0008] In one implemented form, the extension length of the second groove structure in the direction away from the cutting edge is 20 μm or more and 100 μm or less.
[0009] In one realized form, the solar cell further includes a second passivation layer formed on the edge region of the first surface, the edge region of the first surface is close to the cut surface, and the second passivation layer and the first passivation layer are continuously distributed.
[0010] When the above technical solution is adopted, the second passivation layer can passivate the edge region near the cut surface on the first surface, reducing the carrier recombination rate on the first surface and improving the photoelectric conversion efficiency of the solar cell. Furthermore, when the second passivation layer covers the second groove structure, it can passivate and repair the second groove structure, thereby improving the conversion efficiency of the solar cell.
[0011] In one embodiment, the width of the second passivation layer is greater than the extension length of the second groove structure in the direction from the edge of the first surface to the central region of the first surface.
[0012] The second passivation layer covers the second groove structure, allowing it to passivate and repair the structure, thereby improving the conversion efficiency of the solar cell.
[0013] In one implementation, the width of the second passivation layer is 0.05 mm or more and 2 mm or less in the direction from the edge of the first surface to the central region of the first surface.
[0014] In one implementation, the thickness of the first passivation layer is greater than the thickness of the second passivation layer.
[0015] In one implementation, the thickness of the second passivation layer gradually decreases in the direction from the edge of the first surface to the central region of the first surface.
[0016] In one implementation, the thickness of the second passivation layer is between 30 nm and 200 nm.
[0017] In one embodiment, the cut surface includes a first region adjacent to the cutting edge and a second region further from the cutting 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.
[0018] The first region, near the cutting edge, is greatly affected by direct external forces and therefore has complex components and surface morphology, such as silicon shapes other than single-crystal silicon. The silicon in this region contains irregularly arranged amorphous shapes, and in many cases, there are a large number of defects and dangling bonds. Furthermore, the complex surface morphology leads to serious defect formation. Therefore, the presence of more oxygen elements can sufficiently react the silicon in this region, eliminating the resulting negative effects. However, the second region, compared to the first region, is not directly affected by external forces, or the direct external forces are weaker, and its crystal structure is basically that of perfect single-crystal silicon. Introducing too much oxygen in this region may generate more surface defects. Therefore, by setting the ratio of oxygen elements to aluminum elements in at least a part of the first region to be greater than the ratio of oxygen elements to aluminum elements in at least a part of the second region, the effects of the different surface morphologies in the first and second regions are balanced, further improving the overall efficiency of the solar cell.
[0019] In one realized form, 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.
[0020] When the above technical solution is adopted, a first passivation layer is formed on the cut surface. The first passivation layer passivates the cut surface, reducing the recombination rate of photoexcited carriers at the cut surface and improving the photoelectric conversion efficiency of the solar cell. Furthermore, the first groove structure is densely distributed and has a complex structure, and may contain non-single-crystal silicon components. As a result, the surface shape and composition of this region become complex, and the density of surface recombination centers increases. Therefore, if the thickness of the first passivation layer is set to be greater than the depth of the first groove structure, the first passivation layer can completely fill the first groove structure, passivating and repairing it to the maximum extent, thereby improving the conversion efficiency of the solar cell. Furthermore, since many of the crack structures are formed by spontaneous fracture due to stress and have smooth surfaces, setting the thickness of the first passivation layer to be smaller than the depth of the crack structure is sufficient for the limited passivation in that region. Also, the first passivation layer formed on the cut surface becomes higher and lower, improving the light confinement effect on the cut surface and increasing the photoexcited carrier concentration on the cut surface. This improves the light utilization rate of the solar cell cut surface and further improves the photoelectric conversion efficiency of the solar cell. In one realized embodiment, the depth of the first groove structure is smaller than 1.2 μm, which reduces the degree of damage to the solar cell caused by the first groove structure and ensures that the cells do not crack or have too many defects introduced during subsequent manufacturing.
[0021] In one realized form, the depth of the crack structure is 1 μm or more, which ensures uniformity of the plating film and light confinement during the passivation process.
[0022] In one implementation, the thickness of the first passivation layer is 30 nm to 200 nm. When the above technical solution is adopted, the passivation effect of the solar cell gradually increases, and the conversion efficiency increases with increasing thickness of the first passivation layer.
[0023] In one implementation form, the difference between the aluminum content in at least a part of the second region and the aluminum content in at least a part of the first region is greater than 3%.
[0024] When adopting the above technical solution, it can be ensured that different passivation surfaces (i.e., different regions) achieve the required passivation effects.
[0025] In one implementation form, the first groove structure is close to the cutting edge. The first groove structure includes an end portion extending from the cutting edge towards the fracture edge, and the end boundary of the first groove structure is wavy or serrated.
[0026] When adopting the above technical solution, it is possible to avoid excessive concentration of the stress on the cutting surface of the solar cell and improve the quality of the cutting surface.
[0027] In one implementation form, the cutting surface includes an edge region and an intermediate region. The edge region is close to the cutting edge or the fracture edge. The intermediate region is located in the middle part of the cutting surface, and the roughness of the first passivation layer located in the intermediate region is smaller than the roughness of the first passivation layer located in the edge region.
[0028] When adopting the above technical solution, it is possible to avoid sunlight leakage as much as possible and ensure the passivation effect.
[0029] In one implementation form, the distance between the peaks of the wave shape or the serrations is 3 μm or more and 20 μm or less.
[0030] When adopting the above technical solution, since the distance between the peaks is 3 μm or more, it is possible to avoid excessive concentration and distribution of the first groove structure at this time, thereby avoiding excessive concentration of the stress on the cutting surface of the solar cell and improving the quality of the cutting surface.
[0031] In one implementation form, there is an included angle between the extending direction of the crack structure and the extending direction of the first groove structure, and the included angle is 45° or more and less than 90°.
[0032] In one implemented form, the extension length of the first groove structure in the cross-section is 1 μm or more and 20 μm or less.
[0033] By employing the above technical solution, damage to the silicone sheet due to cracks can be reduced.
[0034] In one implementation, the first surface is either a light-receiving surface or a non-light-receiving surface.
[0035] In a second embodiment, the application further provides a solar module including the solar cell described in the first embodiment.
[0036] Compared to conventional technology, the beneficial effects of the solar module provided in this application are the same as the beneficial effects of the solar cell described in the technical solution above, and will not be explained again here. [Brief explanation of the drawing]
[0037] The drawings described herein are intended to further illustrate this application and to constitute part of it, and the exemplary embodiments and descriptions herein are for interpretive purposes only and are not intended to improperly limit this application.
[0038] [Figure 1] This is an SEM view of a cross-section in an embodiment of this application. [Figure 2] This is a schematic diagram of the structure of a solar cell in which a first passivation layer, a second passivation layer, and a third passivation layer are formed according to an embodiment of this application. [Figure 3] This is an SEM diagram of the embodiment of this application after the first passivation layer has been formed on the cross-section. [Modes for carrying out the invention]
[0039] To make the technical problem, technical solution, and beneficial effects that this application aims to solve clearer and easier to understand, this application will be described in more detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are for interpretation purposes only and are not intended to limit this application.
[0040] When an element is described as being "fixed to" or "installed" on another element, it is necessary to explain that it may be directly attached to the other element or indirectly attached to it. When an element is described as being "connected" to another element, it may be directly connected to the other element or indirectly connected to it.
[0041] Furthermore, the terms “first” and “second” are used solely for descriptive purposes and should not be understood as indicating or implying relative importance or the quantity of the technical feature being referred to. Accordingly, features designated as “first” or “second” may be explicitly or implicitly defined as including one or more such features. In this application, unless explicitly and specifically limited, “multiple” means two or more. Unless explicitly and specifically limited, “several” means one or more.
[0042] In the description of this application, the directions or positional relationships indicated by terms such as "up," "down," "front," "back," "left," and "right" are directions or positional relationships shown based on the drawings. The purpose of this is simply to make the description of this application easier to understand and to simplify the description. It is important to understand that this does not explicitly or implicitly suggest that the shown devices or elements necessarily have a specific direction, or are composed and operated in a specific direction, and therefore should not be understood as limiting this application.
[0043] In the description of this application, unless otherwise explicitly defined or limited, the terms “attach,” “connect,” and “join” should be understood in a broad sense. For example, a connection may be fixed, detachable, integral, mechanical, electrically, directly, indirectly via an intermediate medium, or it may be an internal communication between two elements or an interaction between two elements. Those skilled in the art will understand the specific meaning of the above terms in this application depending on the specific situation.
[0044] To solve the above technical problems, in a first embodiment, the present application provides a solar cell. Referring to Figures 1 and 2, the solar cell includes opposing first and second surfaces and a side surface connecting the first and second surfaces. The side surface includes a cut surface 1 and a first passivation layer 4 formed on the cut surface 1, and the cut surface 1 includes opposing cutting edges and fracture edges. In the battery cell cutting process, the battery cell is made breakable or fracture is induced by causing a certain degree of damage to the first surface of the battery cell by an external direct action. For example, first, a certain amount of damage is formed on the first surface by mechanically cutting or irradiating it with a laser, and then the entire solar cell is fractured by stress changes to form a complete cut surface 1. Here, the cutting edge is the first surface on the cut surface 1 that is subjected to an external direct action applied in close proximity to the battery cell, and the fracture edge is in close proximity to the second surface.
[0045] The solar cell further includes a first passivation layer 4 formed on the cut surface 1, and a second passivation layer formed in the edge region of the first surface and continuously distributed with respect to the first passivation layer. The first passivation layer includes an aluminum oxide passivation layer. The cut surface includes a first groove structure 2 and a crack structure 3. The first surface includes the second groove structure, the second groove structure is close to the cut edge, and the edge region of the first surface is close to the cut surface.
[0046] The first region near the cut edge is a region greatly affected by direct external forces, and therefore has complex components and surface morphology, such as silicon shapes other than single-crystal silicon. The silicon in this part contains irregularly arranged amorphous shapes, and in many cases there are a large number of defects and dangling bonds, and the complex surface morphology makes defect formation serious. Therefore, by providing the first passivation layer 4, passivation of the cut surface can be achieved, and the recombination of nearby carriers and defects can be reduced. In addition, because the second groove structure exists on the first surface, it itself causes defects on the first surface of the battery cell, and then carriers generated in the edge region close to the cut surface 1 inside the battery cell body move close to the cut surface and are more likely to recombine with defects on it, resulting in efficiency loss, and therefore the edge region also requires better passivation. The second passivation layer passesivates the edge region of the first surface close to the cut surface 1, reduces the rate of carrier recombination on the first surface, and can improve the photoelectric conversion efficiency of the solar cell.
[0047] In one selectable form, the extension length of the second groove structure in the direction away from the cutting edge is 20 μm or more and 100 μm or less. 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, etc.
[0048] One possible implementation is, as shown in Figure 2, where the width W of the second passivation layer 5 is greater than the extension length of the second groove structure in the direction from the edge of the first surface to the central region of the first surface.
[0049] As one possible implementation, referring to Figure 2, the width W of the second passivation layer 5 is 0.05 mm or more and 2 mm or less. For example, the width W of the second passivation layer 5 may 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 1 mm or more and 2 mm or less. For example, the width of the second passivation layer may be 1 mm, 1.05 mm, 1.35 mm, 1.55 mm, 1.85 mm, or 2 mm.
[0050] In one of the selectable configurations, the thickness of the first passivation layer is greater than the thickness of the second passivation layer.
[0051] In one of the selectable configurations, the thickness of the second passivation layer gradually decreases in the direction from the edge of the first surface to the central region of the first surface.
[0052] In one selectable configuration, the thickness of the second passivation layer in the direction from the edge of the first surface to the central region of the first surface is between 30 nm and 200 nm. For example, the thickness of the second passivation layer may 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.
[0053] In one selectable form, the cross-section includes a first region close to the cutting edge and a second region further from the cutting 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. The first region, close to the cutting edge, is a region greatly affected by direct external forces and therefore has complex components and surface morphology, such as silicon shapes other than single-crystal silicon. The silicon in this region contains irregularly arranged amorphous shapes, often containing a large number of defects and dangling bonds, and the complex surface morphology leads to serious defect formation. Therefore, the presence of more oxygen can sufficiently react the silicon in this region, eliminating the resulting undesirable effects. However, the second region, compared to the first region, is not directly affected by external forces, or is only weakly affected by them, and basically has a perfect single-crystal silicon crystalline structure. Introducing too much oxygen may generate more surface defects. Therefore, by setting the ratio of oxygen to aluminum elements in at least a portion of the first region to be greater than the ratio of oxygen to aluminum elements in at least a portion of the second region, the effects of the different surface shapes of the first and second regions are balanced, and the overall efficiency of the solar cell is further improved.
[0054] One possible implementation is that the first region is the area extending 30 μm from the cut edge to the fracture edge, and the second region is the area other than the first region. When the first region is the area extending 30 μm from the cut edge to the fracture edge, the area where external forces directly act is limited, the stress on the cut surface of the solar cell is balanced overall, the risk of the cell tearing during solar module packaging is reduced, and by employing this passivation means, the cut and fractured area can be effectively passivated and repaired, ensuring a repair effect.
[0055] The aluminum content in at least a portion of the area located in the first region is less than the aluminum content in at least a portion of the area located in the second region. For example, the difference between the aluminum content in at least a portion of the second region and at least a portion of the first region is greater than 3%. In this case, it can be ensured that different passivation surfaces (i.e., different regions) achieve the required passivation effect.
[0056] In one of the selectable forms, the aluminum content in at least a portion of the first region is 1% or more and 3% or less. 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%, etc. The aluminum content in at least a portion of the second region is 4% or more and 7% or less. 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%, etc.
[0057] [Table 1]
[0058] As can be seen from Table 1, the ratio of oxygen to aluminum in the first region is greater than 3, but 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 5 or greater, for example, 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 between 3 and 8, for example, 3, 4, 5, 6, 7, or 8.
[0059] The above-mentioned solar cell includes a semiconductor substrate. For example, the semiconductor substrate may be a silicon substrate. In terms of conductivity type, the solar cell may be an intrinsically 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 to an intrinsically conductive substrate, an N-type conductive substrate or a P-type conductive substrate has higher conductivity, which is advantageous in reducing the series connection resistance of the solar cell and improving the efficiency of the solar cell. In terms of structure, the first surface of the solar cell may be a suede surface, which improves the light confinement effect of the light-receiving surface in the solar cell and further improves the light utilization rate of the solar cell. Naturally, the first surface of the solar cell may also be a flat polished surface. The second surface of the solar cell may be a polished surface or a suede surface, and is not specifically limited here.
[0060] In another embodiment of this application, the first groove structure 2 is located in a first region, and the thickness of the first passivation layer 4 is greater than the depth of the first groove structure 2 but less than the depth of the crack structure 3. For example, the crack structure extends roughly across the entire cut surface, from the cutting edge to the fracture edge.
[0061] Referring to Figures 1 and 2, in the solar cell provided in the embodiment of this application, a first passivation layer 4 is formed on the cut surface. Therefore, the first passivation layer 4 passivates the cut surface 1, reducing the recombination rate of photoexcited carriers at the cut surface and improving the photoelectric conversion efficiency of the solar cell. Furthermore, since the first groove structure is densely distributed and has a complex structure, and may contain non-single-crystal silicon components, the surface shape and composition of this region become complex, and the density of surface recombination centers increases. Consequently, if the thickness of the first passivation layer 4 is set to be greater than the depth of the first groove structure 2, the first passivation layer 4 can completely fill the first groove structure 2, passivating and repairing it to the maximum extent, thereby improving the conversion efficiency of the solar cell. Furthermore, since many of the crack structures 3 are formed by spontaneous fracture due to stress, and their surfaces are smooth, setting the thickness of the first passivation layer 4 to be smaller than the depth of the crack structures 3 is sufficient for the limited passivation in that region. Also, the first passivation layer 4 formed on the cut surface 1 becomes uneven in height, improving the light confinement effect of the cut surface 1 and increasing the photoexcited carrier concentration of the cut surface 1. This improves the light utilization rate of the solar cell cut surface 1 and further improves the photoelectric conversion efficiency of the solar cell. In addition, since the entire surface of the crack structure 3 is smooth and regular, it is advantageous for light absorption.
[0062] One possible implementation is that the statement that 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 can be understood as the average thickness of the first passivation layer being greater than the maximum depth of the first groove structure and less than the minimum depth of the crack structure. Alternatively, it can be understood as the average thickness of the first passivation layer being greater than the average depth of the first groove structure and less than the average depth of the crack structure.
[0063] One possible implementation is that the thickness of the first passivation layer is between 30 nm and 200 nm. For example, the thickness of the first passivation layer may 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 increases with increasing thickness of the first passivation layer. Furthermore, if the passivation layer is too thin, the passivation effect will be insufficient, and if the passivation layer is too thick, the edge effect of the resulting passivation effect will decrease, as well as the process time and material consumption will increase.
[0064] Next, we will explain the relevant parameters of a solar cell using a first passivation layer of different thicknesses as an example.
[0065] [Table 2]
[0066] Here, BSL represents the control group, and 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 curve factor.
[0067] One possible implementation is shown in Figures 1 and 3, where the cut surface 1 includes an edge region 11 and an intermediate region 12. The edge region 11 is close to the cutting edge or fracture edge, and the intermediate region 12 is located in the middle of the cut surface 1. The roughness of the first passivation layer 4 located in the intermediate region 12 is smaller than the roughness of the first passivation layer 4 located in the edge region 11. In this case, it is possible to avoid sunlight escaping as much as possible and ensure the passivation effect.
[0068] One possible implementation is that, in the direction away from the cutting edge, the extension length of the first groove structure on the cut surface is between 1 μm and 20 μm. In this case, by controlling the overall distribution area of the first groove structure, effective cutting of the battery cell can be guaranteed without introducing too many defects to the cut surface. For example, the extension length of the first groove structure may be 1 μm, 3 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, or 20 μm.
[0069] One possible implementation is that the depth of the first groove structure is less than 1.2 μm. This reduces the degree of damage to the solar cell caused by the first groove structure, ensuring that the cells do not tear or have too many defects introduced during subsequent fabrication.
[0070] As one possible implementation, referring to Figure 1, the first groove structure 2 is distributed in the first region, is close to the cutting edge, extends from the cutting edge to the fracture edge, includes an end that extends from the cutting edge to the fracture edge, and the end boundary M of the first groove structure 2 is wavy or sawtooth-shaped.
[0071] At this time, it is possible to avoid excessive stress accumulation at the cut surface of the solar cell and improve the quality of the cut surface. Note that the first groove end boundary mentioned above refers to the boundary away from the cutting edge.
[0072] One possible implementation is a crack structure with a depth of 1 μm or more and a smooth surface, which ensures uniformity of the plating film and light confinement during the passivation process.
[0073] One possible implementation is that the depth of the crack structure located within the region where the first groove structure exists is between 1 μm and 2 μm. For example, the depth of the crack structure may be 1 μm, 1.2 μm, 1.5 μm, 1.7 μm, 1.9 μm, or 2 μm.
[0074] The depth of the crack structure, which is located away from the region where the first groove structure exists, is between 1 μm and 2 μm. For example, the depth of the crack structure may be 1 μm, 1.2 μm, 1.5 μm, 1.7 μm, 1.9 μm, or 2 μm.
[0075] As one possible implementation, referring to Figure 1, the first groove structure 2 may be distributed in a dendritic, branched, or curved manner. In this case, it is possible to avoid excessive accumulation of stress on the cross-section of the solar cell and improve the quality of the cross-section.
[0076] In one selectable configuration, referring to Figure 1, the horizontal spacing L between the wavy or sawtooth peaks is between 3 μm and 20 μm. For example, the horizontal spacing L may be 3 μm, 5 μm, 8 μm, 10 μm, 12 μm, 13 μm, 15 μm, 18 μm, 19 μm, or 20 μm. Because the spacing between peaks is 3 μm or more, it is possible to avoid excessive concentration and distribution of the first groove structure, thereby preventing excessive accumulation of stress on the cross-section of the solar cell and improving the quality of the cross-section.
[0077] In one selectable embodiment, referring to Figure 1, there is an angle A between the extending direction of the crack structure 3 and the extending direction of the first groove structure 2, and the presence of angle A can induce further uniformity of the distribution of crack depth and width. Angle A is preferably 45° or more and less than 90°. For example, angle A may be 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, or 89°.
[0078] In one selectable embodiment, referring to Figure 2, the solar cell further includes a second passivation layer 5 formed on the 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.
[0079] When the above technical solution is adopted, the second passivation layer can passivate the edge region near the cut surface on the first surface, reducing the carrier recombination rate on the first surface and improving the photoelectric conversion efficiency of the solar cell. Furthermore, when the second passivation layer covers the second groove structure, it can passivate and repair the second groove structure, thereby improving the conversion efficiency of the solar cell.
[0080] One possible implementation is that the solar cell further includes a third passivation layer formed in the edge region of the second surface, where the edge region of the second surface is close to the cut surface, and the third passivation layer and the first passivation layer are continuously distributed.
[0081] When the above technical solution is adopted, the third passivation layer passivates the edge region near the cut surface on the second surface, reducing the carrier recombination rate on the second surface and improving the photoelectric conversion efficiency of the solar cell.
[0082] One possible implementation may include, in addition to the first passivation layer, the second passivation layer, and the third passivation layer, at least one of other passivation layers laminated above or below the first passivation layer, the second passivation layer, or the third passivation layer, such as silicon oxide, silicon nitride, or silicon oxynitride.
[0083] In one selectable configuration, the width of the third passivation layer in the direction from the edge of the second surface to the central region of the second surface is between 20 μm and 100 μm. For example, the width of the third passivation layer 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.
[0084] In one of the selectable configurations, the thickness of the first passivation layer is greater than the thickness of the third passivation layer.
[0085] In one of the selectable configurations, the thickness of the third passivation layer gradually decreases in the direction from the edge of the second surface to the central region of the second surface.
[0086] In one selectable configuration, the thickness of the third passivation layer is 30 nm to 200 nm in the direction from the edge of the second surface to the central region of the second surface. For example, the thickness of the third passivation layer may 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.
[0087] In one selectable form, the first surface is either a light-receiving surface or a non-light-receiving surface. The solar cell may be a double-sided 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, and of course, the solar cell may be a solar cell including a tunnel passivation structure or other types of solar cells including a heterojunction structure.
[0088] In a second embodiment, the embodiments of this application further provide a solar module including the solar cell described in the first embodiment.
[0089] The solar module includes a battery string formed by interconnecting a plurality of solar cells, wherein the battery string includes a welded interconnection structure, such as a welding strip or welding wire, which electrically interconnects two adjacent solar cells, wherein the welded interconnection structure has a head and a tail, and at least one of the head and tail of the welded interconnection structure is close to the cut surface of the solar cell. For example, the two adjacent solar cells are a first solar cell and a second solar cell. The welded interconnection structure electrically interconnects the adjacent first solar cell and second solar cell, and 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 the side surface of the second solar cell facing the cut surface, or from a position near the side surface of the first solar cell facing the cut surface to a position near the cut surface of the second solar cell. The head and tail portions of a welded interconnect structure are difficult to control in terms of position and displacement during the welding process, which can damage the passivation dielectric layer and even penetrate it. In this application, a first passivation layer is formed on the cut surface of the battery cell, and a second passivation layer is separately formed on the edge regions of the first and second surfaces adjacent to the cut surface. As a result, these edge regions of the first and second surfaces have a thick dielectric layer, providing sufficient protection for these edges of the battery cell and reducing the probability that the head and tail portions of the welded interconnect structure will penetrate the passivation dielectric layer. Furthermore, at least one of the head and tail portions of the welded interconnect structure extends above the second passivation layer in the edge region of the first or second surface.
[0090] The beneficial effects of the solar module provided in the embodiments of this application are the same as the beneficial effects of the solar cell described in the technical solution above, and will not be explained again here.
[0091] In the above description of embodiments, specific features, structures, materials, or characteristics can be combined in an appropriate manner in any one or more embodiments or examples.
[0092] The above are merely specific embodiments of the present application, and the scope of protection of this application is not limited thereto. Any changes or replacements that a person skilled in the art could easily conceive of within the scope of the art described in this application are all included in the scope of protection of this application. Therefore, the scope of protection of this application shall be the same as the scope of protection of the claims. [Explanation of Symbols]
[0093] 1 Cut surface 11 Edge region 12 Intermediate area 2 First groove structure 3. Crack structure 4. First Passivation Layer 5. Second Passivation Layer
Claims
1. It is a solar cell, Including opposing first and second surfaces, and a side surface connecting the first and second surfaces, The aforementioned side surface includes a cut surface that includes a cutting edge adjacent to the first surface and a fracture edge adjacent to the second surface. The solar cell includes a first passivation layer formed on the cut surface and a second passivation layer formed in the edge region of the first surface and continuously distributed with respect to the first passivation layer. The first passivation layer comprises an aluminum oxide passivation layer, and the cross-section comprises a first groove structure and a crack structure. A solar cell characterized in that the first surface includes a second groove structure, the second groove structure is close to the cutting edge, and the edge region of the first surface is close to the cutting surface.
2. The solar cell according to claim 1, characterized in that the extension length of the second groove structure in the direction away from the cutting edge is 20 μm or more and 100 μm or less.
3. The solar cell according to claim 1, characterized in that the width of the second passivation layer is greater than the extending length of the second groove structure in the direction from the edge of the first surface to the central region of the first surface.
4. The solar cell according to claim 1, characterized in that the width of the second passivation layer is 0.05 mm or more and 2 mm or less in the direction from the edge of the first surface to the central region of the first surface.
5. The solar cell according to claim 1, characterized in that the thickness of the first passivation layer is greater than the thickness of the second passivation layer.
6. The solar cell according to claim 1, characterized in that the thickness of the second passivation layer gradually decreases in the direction from the edge of the first surface toward the central region of the first surface.
7. The solar cell according to claim 1, characterized in that the thickness of the second passivation layer is 30 nm or more and 200 nm or less.
8. The cut surface includes a first region adjacent to the cutting edge and a second region further from the cutting edge than the first region. The solar cell according to claim 1, characterized in that 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.
9. The solar cell according to claim 8, characterized in that the first groove structure is located in the first region, and 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.
10. The solar cell according to claim 1, characterized in that the depth of the first groove structure is less than 1.2 μm, or the depth of the crack structure is 1 μm or more.
11. The solar cell according to claim 1, characterized in that the thickness of the first passivation layer is 30 nm or more and 200 nm or less.
12. The solar cell according to claim 8, characterized in that 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%.
13. The solar cell according to claim 1, characterized in that the first groove structure is close to the cutting edge, the first groove structure includes an end extending from the cutting edge toward the fracture edge, and the end boundary of the first groove structure is wavy or sawtooth-shaped.
14. The solar cell according to claim 1, wherein the cut surface includes an edge region and an intermediate region, the edge region is close to the cut edge or the fracture edge, the intermediate region is located in the intermediate portion of the cut surface, and the roughness of the first passivation layer located in the intermediate region is smaller than the roughness of the first passivation layer located in the edge region.
15. The solar cell according to claim 13, characterized in that the spacing between the wavy or sawtooth-shaped peaks is 3 μm or more and 20 μm or less.
16. The solar cell according to claim 1, characterized in that there is an angle between the extending direction of the crack structure and the extending direction of the first groove structure, and the angle is 45° or more and less than 90°.
17. The solar cell according to claim 1, characterized in that the extension length of the first groove structure in the cross-section is 1 μm or more and 20 μm or less.
18. The solar cell according to any one of claims 1 to 17, characterized in that the first surface is a light-receiving surface or a non-light-receiving surface.
19. A solar module characterized by including a solar cell according to any one of claims 1 to 19.