Solar cells and photovoltaic modules

Abstract

The application discloses a solar cell and a photovoltaic module, and relates to the technical field of solar cells, and aims to improve the photoelectric conversion efficiency of the solar cell. The solar cell comprises a first passivation contact structure formed on a first surface of a semiconductor substrate; a first bus electrode and a first collecting electrode formed above the first passivation contact structure; at least part of the first bus electrode comprises a first end plate close to a first edge of the semiconductor substrate and at least two first sub-bus electrodes connected to the first end plate; a region between the two outermost first sub-bus electrodes constitutes a first end bus electrode region; the first passivation contact structure has a first hollow region and a second hollow region; the first hollow region is located in the first end bus electrode region; and the second hollow region is located outside the first end bus electrode region and between the first collecting electrodes.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and more particularly to a solar cell and a photovoltaic module. Background Technology

[0002] A solar cell is a device that utilizes solar energy, converting light energy into electrical energy through the photovoltaic effect. The aforementioned solar cells include tunnel oxide passivated contact solar cells (TOPCon). TOPCon cells have a passivated contact structure on the back side consisting of a tunnel oxide layer and a doped polycrystalline silicon layer, improving the passivation performance of the back side.

[0003] Because the doped polycrystalline silicon layer formed on the back side parasitizes light absorption, it reduces light utilization and affects the light utilization and battery efficiency on the back side of the battery.

[0004] Therefore, improving the photoelectric conversion efficiency of solar cells is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] The purpose of this invention is to provide a solar cell and a photovoltaic module for improving the photoelectric conversion efficiency of solar cells.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a solar cell. The solar cell includes: a semiconductor substrate, a first passivation contact structure, a first bus electrode, and a first current collector electrode. The semiconductor substrate includes opposing first and second surfaces; along a first direction, the semiconductor substrate includes opposing first and second edges; the first passivation contact structure is formed on the first surface of the semiconductor substrate; the first current collector electrode is formed above the first passivation contact structure; a plurality of first current collector electrodes extend along a second direction and are spaced apart along the first direction. The first bus electrode is formed above the first passivation contact structure; the first bus electrode intersects with the plurality of first current collector electrodes. At least a portion of the first bus electrode includes: a first end pad near the first edge and a first end bus electrode connected to the first end pad, the first end bus electrode being located between the first end pad and the first edge. The first end bus electrode includes at least two first sub-bus electrodes; the region between the two outermost first sub-bus electrodes constitutes the first end bus electrode region. The first passivated contact structure has a first hollow area and a second hollow area; the first hollow area is located within the first end bus electrode area; the second hollow area is located outside the first end bus electrode area and between the first collector electrodes.

[0007] In the solar cell provided by this invention, the first bus electrode is formed above the first passivated contact structure. The first bus electrode does not directly contact the semiconductor substrate, which reduces metal recombination in the solar cell, increases the open-circuit voltage, and thus improves the cell efficiency. Furthermore, since the first current collector electrode is formed above the first passivated contact structure and is electrically connected to it, not only can the contact resistivity and series resistance be reduced to effectively collect current and reduce electrical losses, thus improving the cell efficiency, but the carrier transport distance can also be reduced to minimize recombination losses during transport. Further, the first passivated contact structure has a first hollow region and a second hollow region. The first hollow region is located within the first end bus electrode region; the second hollow region is located outside the first end bus electrode region and between the first current collector electrodes. This application achieves dual optimization of optical and electrical performance by introducing a first hollow region into the first end bus electrode region. This design firstly significantly improves the effective utilization rate of incident light by reducing light absorption losses in the power generation area of ​​the solar cell, enabling more photons to participate in the photoelectric conversion process. More importantly, by setting a first hollowed-out area within the first end busbar electrode region, it solves the current collection mismatch problem existing in the prior art, namely the phenomenon that the uneven distribution of the electric field inside the cell leads to low collection efficiency of photogenerated carriers in some areas. By matching the first hollowed-out area within the first end busbar electrode region with a second hollowed-out area outside the first end busbar electrode region, it not only significantly improves the effective collection efficiency of carriers in the electrode region, but also effectively suppresses non-radiative recombination losses. Thus, while increasing the short-circuit current (Jsc), it also improves key performance parameters such as fill factor (FF) and open-circuit voltage (Voc), ultimately achieving a significant improvement in the overall conversion efficiency of the solar cell.

[0008] In one implementation, at least a portion of the first bus electrode further includes: a first bus electrode connecting line, a plurality of first bus electrode connecting lines extending along a first direction and spaced apart along a second direction; and a first end pad disposed at one end of the first bus electrode connecting line near a first edge.

[0009] In one implementation, the widths of the first cutout area and the second cutout area are equal in the first direction; the first cutout area has a first center line extending in the second direction; and the second cutout area adjacent to the first cutout area has a second center line extending in the second direction.

[0010] The first center line and the second center line are collinear; and / or, along the first direction, the ratio of the distance between the first center line and the second center line to the width of the first hollow area along the first direction or to the width of the second hollow area along the first direction is less than or equal to 10%.

[0011] When using the above technical solution, the first and second hollowed-out areas are formed after laser processing of the first passivated contact structure. If the ratio is greater than 10%, it indicates that during the laser processing of the first passivated contact structure, the offset of the first hollowed-out area relative to the second hollowed-out area in the first direction is too large, or the offset of the second hollowed-out area relative to the first hollowed-out area in the first direction is too large. In this case, it is very easy for the first or second hollowed-out area to be located below the first collector electrode, causing the first passivated contact structure corresponding to the first collector electrode to be broken. That is, it is easy for the laser to remove part of the first passivated contact structure corresponding to the first collector electrode, resulting in the first collector electrode being directly welded to the semiconductor substrate when it is subsequently formed, generating carrier recombination centers and metal recombination, reducing the short-circuit current and fill factor of the solar cell, and increasing the contact resistance.

[0012] In summary, when the ratio of the distance between the first center line and the second center line to the width of the first hollow area along the first direction or to the width of the second hollow area along the first direction is less than or equal to 10%, the first collector electrode can be prevented from being directly welded to the semiconductor substrate, thus avoiding the generation of carrier recombination centers and metal recombination. This increases the open-circuit voltage of the solar cell, improves the short-circuit current and fill factor of the solar cell, reduces the contact resistance, and thereby improves the cell efficiency of the solar cell.

[0013] In one implementation, the first end busbar region has a plurality of first hollow regions spaced apart along a first direction.

[0014] By adopting the above technical solution, not only can the shading of the semiconductor substrate by the first passivation contact structure be effectively reduced, and the parasitic absorption of light by the first passivation contact structure be reduced, but also the light absorption loss in the power generation area of ​​the solar cell be reduced, and the light energy loss be reduced, significantly improving the effective utilization rate of incident light, allowing more photons to be transferred to the semiconductor substrate, thereby enabling more photons to participate in the photoelectric conversion process and improving the photoelectric conversion efficiency of the solar cell. Simultaneously, it can also increase the carrier generation rate in the first end current collector electrode region and reduce the recombination rate. Furthermore, it further solves the current collection mismatch problem existing in the prior art.

[0015] In one implementation, two adjacent first hollow areas are staggered in the first direction.

[0016] When the above technical solution is adopted, the first hollow area is opened on the first passivated contact structure, which will disrupt the original stress distribution and cause stress concentration at the edge of the first hollow area. When two adjacent first hollow areas are staggered in the first direction, the stress can be dispersed to different directions, avoiding the overlap of stress concentration areas and reducing the risk of local fracture. Furthermore, it can reduce the probability of the first passivated contact structure below the first current collector and the first bus electrode fractured due to stress concentration when the first current collector and the first bus electrode are subsequently fabricated on the first passivated contact structure with the first hollow area. This reduces or avoids the generation of carrier recombination centers and metal recombination, thereby increasing the open-circuit voltage of the solar cell, improving the short-circuit current and fill factor of the solar cell, and thus improving the cell efficiency of the solar cell. In addition, the staggered arrangement of two adjacent first hollow areas in the first direction can disperse processing errors, avoiding the cumulative errors during processing from causing the positional deviations of all first hollow areas to be superimposed along the first direction. This prevents processing errors from exceeding the design error, improves the fault tolerance rate, and thus improves the quality of the solar cell.

[0017] In one implementation, the distance between two second cutout regions located on both sides of the first end pad along the second direction is L1, and the distance between two second cutout regions located on both sides of the first bus electrode connection line along the second direction is L2, satisfying that L1 is greater than L2.

[0018] By adopting the above technical solution, the removal of the corresponding first passivation contact structure below the first end pad can be reduced or avoided when forming two second hollow areas located on both sides of the first end pad along the second direction, thereby reducing or avoiding direct contact between the first end pad and the semiconductor substrate below it. This not only reduces or avoids the formation of recombination centers, improving minority carrier lifetime and battery open-circuit voltage, but also reduces contact resistance and improves current collection efficiency.

[0019] In one implementation, along the second direction, the distances between the two second hollowed-out areas located on both sides of the first bus electrode connection line and the first bus electrode connection line are not equal.

[0020] When the above technical solution is adopted, during the subsequent formation of photovoltaic modules, conductive connectors such as solder strips are welded to the first busbar electrode connection line. Since the distance between the two second hollow areas located on both sides of the first busbar electrode connection line and the first busbar electrode connection line is not equal along the second direction in this application, stress concentration can be reduced and the mechanical strength of conductive connectors such as solder strips can be improved during welding.

[0021] In one implementation, along the second direction, the distance between the first hollow area and the adjacent second hollow area is L5, and the distance between two adjacent first hollow areas along the first direction is L6, satisfying that L5 is greater than L6.

[0022] In the above technical solution, the first passivation contact structure between the second hollow area adjacent to the first hollow area and the first hollow area corresponds to the first sub-bus electrode, and the first passivation contact structure between two adjacent first hollow areas corresponds to the first current collector electrode. Since the contact performance between the first bus electrode and the solar cell is lower than that of the first current collector electrode; or, since the first bus electrode needs to be welded to conductive connectors such as solder strips, the contact area with the solar cell surface or conductive connectors is usually increased by increasing the width of the first bus electrode to improve its contact and welding performance. Furthermore, since the first bus electrode includes a first sub-bus electrode, the width of the first sub-bus electrode is wider. Based on this, in this application, L5 is greater than L6. Further, since the paste forming the first bus electrode has high ductility, the width of the first bus electrode is greater than the width of the first current collector electrode, that is, the width of the first sub-bus electrode is greater than the width of the first current collector electrode. Based on this, in this application, L5 is greater than L6 to improve the tolerance of printing misalignment of the first sub-bus electrode. In addition, the above solution can reduce the parasitic absorption of light by the first passivation contact structure between two adjacent first hollow areas, thereby improving the utilization rate of light.

[0023] In one implementation, along the second direction, the distance between the first hollow area and the adjacent second hollow area is L5, which satisfies 50μm≤L5≤1.5mm.

[0024] When the above technical solution is adopted, if L5 is greater than or equal to 50 μm, along the second direction, the width of the first passivation contact structure between the second hollow area adjacent to the first hollow area and the first hollow area is greater than or equal to 50 μm. This width of the first passivation contact structure provides sufficient space for the subsequent formation of the first sub-bus electrode at the corresponding position above it, ensuring that the width of the first sub-bus electrode above the first passivation contact structure meets actual requirements. Furthermore, if along the second direction, the width of the first passivation contact structure between the second hollow area adjacent to the first hollow area and the first hollow area is less than 50 μm, the first conductive contact layer cannot effectively collect current and is easily removed during cleaning. When L5 is less than or equal to 1.5mm, along the second direction, the width of the first passivation contact structure between the second hollow area adjacent to the first hollow area and the first hollow area is less than or equal to 1.5mm. By controlling the size of the first passivation contact structure at this position, the parasitic absorption of light by the first passivation contact structure is reduced, the light absorption loss in the power generation area of ​​the solar cell is reduced, the light energy loss is reduced, the effective utilization rate of incident light is significantly improved, and more photons can be transmitted to the semiconductor substrate, so that more photons can participate in the photoelectric conversion process and improve the photoelectric conversion efficiency of the solar cell.

[0025] In one implementation, the distance between two adjacent first hollow areas along the first direction is L6, which satisfies 50μm≤L6≤1mm.

[0026] When the above technical solution is adopted, when L6 is greater than or equal to 50 μm, the width of the first passivation contact structure between two adjacent first hollow areas is greater than or equal to 50 μm. This width of the first passivation contact structure provides sufficient space for the subsequent formation of the first current collector electrode at the corresponding position above it, ensuring that the width of the first current collector electrode above the first passivation contact structure meets actual requirements. When L6 is less than or equal to 1 mm, the width of the first passivation contact structure between two adjacent first hollow areas is less than or equal to 1 mm. By controlling the size of the first passivation contact structure at this position, parasitic absorption of light by the first passivation contact structure is reduced, improving light utilization and thus increasing the photoelectric conversion efficiency of the solar cell.

[0027] In one implementation, a portion of the first collector electrode adjacent to the first edge is disconnected at the first end bus electrode region, and the first passivated contact structure corresponding to the first collector electrode extends through the first end bus electrode region along the extension direction of the first collector electrode.

[0028] By adopting the above technical solution, the impact of welding with conductive connectors such as solder strips on the first collector electrode in the first end busbar region can be reduced, minimizing or avoiding the number of damaged first collector electrodes. In particular, the first collector electrode located in the first end busbar region, especially in a portion near the first edge, experiences greater pressure from the conductive connectors such as solder strips after connection, making it more prone to welding failure and even damaging the first passivation contact structure at that location. Therefore, in this application, a portion of the first collector electrode near the first edge is disconnected in the first end busbar region.

[0029] Furthermore, since the first current collector electrode near the first edge is disconnected at the first end busbar region, there is a region without the first current collector electrode, i.e., a blank area, in the first end busbar region, particularly in the region near the first edge. During subsequent photovoltaic module manufacturing, the bent portion of conductive connectors such as solder ribbons utilizes this blank area to connect with other solar cells. This reduces or avoids microcracks or fragmentation of the solar cells caused by the elevation of the first current collector electrode, and lowers the height difference between the conductive connector to be welded to the first side of the first solar cell and the conductive connector to be welded to the second side of the second solar cell, thereby improving the yield of the cell string and solar module. In addition, the first passivated contact structure corresponding to the first current collector electrode extends through the first end busbar region along the extension direction of the first current collector electrode. This enhances the mechanical strength of the solar cell edge and provides a transport channel for charge carriers. Charge carriers can be collected and transported through the penetrating first passivated contact structure, improving short-circuit current and cell efficiency.

[0030] In one implementation, the size of the first cutout region closest to the first end pad is smaller than the size of the first cutout region farther from the first end pad.

[0031] In one implementation, the first cutout region closest to the first end pad is closer to the first collector electrode located within the first end bus electrode region than the first end pad.

[0032] By adopting the above technical solution, the probability of the first passivated contact structure below the first end pad being removed when forming the first cutout area closest to the first end pad can be reduced or avoided, thereby reducing or avoiding direct contact between the first end pad and the semiconductor substrate below it. This not only reduces or avoids the formation of recombination centers, improving minority carrier lifetime and battery open-circuit voltage, but also reduces contact resistance and improves current collection efficiency.

[0033] In one implementation, the solar cell further includes: connecting pads. A plurality of connecting pads are spaced apart along a first direction on a first bus electrode connecting line, and the length of a second hollowed-out area circumferential to the connecting pads along a second direction is less than the length of a second hollowed-out area distant from the connecting pads along the second direction.

[0034] By adopting the above technical solution, the probability of the first passivated contact structure below the connection pad being removed when forming the second cutout area located around the connection pad can be reduced or avoided, thereby reducing or avoiding direct contact between the connection pad and the semiconductor substrate below it. This not only reduces or avoids the formation of recombination centers, improving minority carrier lifetime and battery open-circuit voltage, but also reduces contact resistance and improves current collection efficiency.

[0035] In one implementation, the distance between the first hollowed-out region and the first sub-bus electrode is greater than the distance between the first hollowed-out region and the first collector electrode.

[0036] When the above technical solution is adopted, the function of the first collector electrode is to collect charge carriers. The closer the first hollow area is to the first collector electrode, the more charge carriers are generated around the first collector electrode due to the reduction of parasitic light absorption, and the more charge carriers are collected, which is beneficial to increasing the number of charge carriers. The first sub-collector electrode is used to collect and transmit the current on the first collector electrode. It is not responsible for collecting charge carriers itself. Maintaining a large safety distance can improve the reliability of solar energy and accommodate process errors.

[0037] In one implementation, the distance between the first hollowed-out area and the first sub-bus electrode is greater than or equal to 50 μm and less than or equal to 1.5 mm.

[0038] When the above technical solution is adopted, the first sub-busbar electrode is used to collect and transmit the current on the first collector electrode, and it is not responsible for collecting charge carriers itself. When the distance between the first hollowed-out area and the first sub-busbar electrode is within the above-mentioned range, a large safe distance is maintained between the first hollowed-out area and the first sub-busbar electrode to improve the reliability of solar energy and accommodate process errors.

[0039] In one implementation, the distance between the first hollowed-out area and the first current collector is greater than or equal to 50 μm and less than or equal to 1 mm.

[0040] When the above technical solution is adopted, the function of the first collector electrode is to collect charge carriers. The closer the first hollow region is to the first collector electrode, the more charge carriers are generated around the first collector electrode due to the reduction of parasitic absorption of light, and the more charge carriers are collected, which is beneficial to increasing the number of charge carriers. Therefore, in this application, the distance between the first hollow region and the first collector electrode is set to be greater than or equal to 50 μm and less than or equal to 1 mm.

[0041] In one implementation, for the same first end bus electrode, along the direction close to the first end pad, the spacing between the two outermost first sub-bus electrodes is reduced, the length of the first cutout region between two adjacent first sub-bus electrodes is reduced, and the length direction of the first cutout region is consistent with the second direction.

[0042] With the above technical solution, while ensuring that the first passivation contact structure is present at the corresponding position below the first sub-current collector electrode and the first current collector electrode, the area of ​​the first hollow area is made larger to reduce the parasitic absorption of light by the first passivation contact structure, reduce the light absorption loss in the power generation area of ​​the cell, reduce light energy loss, significantly improve the effective utilization rate of incident light, and enable more photons to be transmitted to the semiconductor substrate, so that more photons can participate in the photoelectric conversion process and improve the photoelectric conversion efficiency of the solar cell.

[0043] In one implementation, for the same first end bus electrode, any two adjacent first sub-bus electrodes are parallel to each other; along the first direction, the length of the first hollow region located between two adjacent first sub-bus electrodes remains unchanged, and the length direction of the first hollow region is consistent with the second direction.

[0044] In one implementation, the second hollow region includes multiple second sub-hollow regions. Along a second direction, the multiple second sub-hollow regions are spaced apart; and / or, along the second direction, the multiple second sub-hollow regions abut each other.

[0045] When the above technical solution is adopted, in the actual formation of the second hollow region, the first passivated contact structure is treated with a laser. The laser spots formed during the laser treatment are arranged along the second direction. When two adjacent laser spots overlap or abut, two adjacent second sub-hollow regions overlap or abut along the second direction. When two adjacent laser spots are spaced apart, two adjacent second sub-hollow regions are spaced apart along the second direction. Therefore, the method of forming the second hollow region can be selected according to actual needs, increasing the application scenarios of solar cells and expanding their applicability. Furthermore, when multiple second sub-hollow regions are spaced apart along the second direction, there is a first passivated contact structure between two adjacent second sub-hollow regions. This first passivated contact structure facilitates the transport of charge carriers, which are transported to the first current collector electrode through this first passivated contact structure, thereby improving the current collection capability of the solar cell.

[0046] In one implementation, a first surface of the semiconductor substrate includes a first region and a second region surrounding the first region; a first bus electrode and a first collector electrode are located within the first region; and a first passivation contact structure is located within both the first and second regions.

[0047] As can be seen from the above, when the above technical solution is adopted, the second region is located between the multiple edges of the semiconductor substrate and the first region. Since a first passivation contact structure is formed in the second region surrounding the first region, compared with the case where no first passivation contact structure is formed in the second region surrounding the first region, this application can improve the mechanical strength of the second region of the solar cell (i.e., the region near the edge of the solar cell) and reduce the breakage rate of the second region of the solar cell.

[0048] In one implementation, the first passivated contact structure also has a third hollowed-out area, which is located within the second area and close to the first edge.

[0049] By adopting the above technical solution, the parasitic absorption of light by the first passivated contact structure can be further reduced, the light utilization rate can be improved, and the photoelectric conversion efficiency of the solar cell can be increased.

[0050] In one implementation, the first end bus electrode includes three first sub-bus electrodes extending along a first direction and spaced apart along a second direction; the region between two adjacent first sub-bus electrodes constitutes a first sub-end bus electrode region; each first sub-end bus electrode region has a first hollowed-out region.

[0051] With the above technical solution, compared to the prior art where there is only a first busbar connection line and no first sub-busbar electrode, the present application increases the number of first sub-busbar electrodes and reduces the area of ​​charge carrier collection for each first sub-busbar electrode. This improves the first sub-busbar electrode's ability to collect charge carriers generated in that area, enhances its current collection ability, and makes the current collection more uniform. Furthermore, during the formation of the photovoltaic module, when conductive connectors such as solder ribbons are simultaneously connected to the first end pad and the first sub-busbar electrode located in the middle of the first end busbar electrode, compared to when the conductive connectors such as solder ribbons are only connected to the first end pad, the present application not only improves the speed of current transmission to the conductive connectors such as solder ribbons and the current collection ability of the conductive connectors such as solder ribbons, reducing current transmission losses, but also improves the connection strength of the conductive connectors such as solder ribbons, thus improving the yield of the solar cells.

[0052] In one implementation, the solar cell further includes:

[0053] A second passivated contact structure is formed on the second side of the semiconductor substrate;

[0054] The second bus electrode is formed above the second passivated contact structure; multiple second bus electrodes extend along the first direction and are spaced apart along the second direction;

[0055] The second bus electrode includes: a second bus electrode connecting line, a third end pad disposed along the first direction near the first edge of the second bus electrode connecting line, and a third end bus electrode connected to the third end pad;

[0056] The third end bus electrode includes at least two third sub-bus electrodes that extend along a first direction and are spaced apart along a second direction; the region between the two outermost third sub-bus electrodes constitutes the third end bus electrode region.

[0057] The second current collector electrode is formed above the second passivated contact structure; multiple second current collector electrodes extend along the second direction and are spaced apart along the first direction; the second bus electrode intersects with the multiple second current collector electrodes;

[0058] The second passivated contact structure has a fourth hollow region and a fifth hollow region; the fourth hollow region is located within the third end bus electrode region; the fifth hollow region is located outside the third end bus electrode region and between the second collector electrodes.

[0059] By adopting the above technical solution, this application achieves dual optimization of optical and electrical performance by introducing a fourth hollow region in the third end busbar electrode region. This design firstly significantly improves the effective utilization rate of incident light by reducing light absorption losses in the cell's power generation area, enabling more photons to participate in the photoelectric conversion process. More importantly, the fourth hollow region in the third end busbar electrode region solves the current collection mismatch problem existing in the prior art, namely, the phenomenon of low collection efficiency of photogenerated carriers in some areas due to uneven electric field distribution inside the cell. By matching the fourth hollow region in the third end busbar electrode region with the fifth hollow region outside the third end busbar electrode region, not only is the effective collection efficiency of carriers in the electrode region significantly improved, but non-radiative recombination losses are also effectively suppressed. This improves key performance parameters such as fill factor (FF) and open-circuit voltage (Voc) while increasing the short-circuit current (Jsc), ultimately achieving a significant improvement in the overall conversion efficiency of the solar cell. Furthermore, the bifaciality of the solar cell is improved by the combined effect of the first and second hollow areas of the first passivation contact structure and the fourth and fifth hollow areas of the second passivation contact structure.

[0060] Secondly, the present invention also provides a photovoltaic module. The photovoltaic module includes a battery string and an encapsulation layer; the battery string includes multiple conductive connectors and multiple solar cells as described in the above-described technical solutions; the conductive connectors connect the multiple solar cells in series; the encapsulation layer is used to cover the surface of the battery string.

[0061] The beneficial effects of the photovoltaic module provided by this invention are the same as those of the solar cell described in the above technical solution, and will not be repeated here. Attached Figure Description

[0062] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0063] Figure 1 This is a partial structural diagram of a solar cell in an embodiment of the present invention, where the first end busbar electrode includes two first sub-busbar electrodes. Figure 1 ;

[0064] Figure 2 This is a partial structural diagram of a solar cell in an embodiment of the present invention, where the first end busbar electrode includes two first sub-busbar electrodes. Figure 2 ;

[0065] Figure 3 This is a partial structural diagram of a solar cell in an embodiment of the present invention, where the first end busbar electrode includes three first sub-busbar electrodes;

[0066] Figure 4 This is a schematic diagram of the structure after the conductive connector and two solar cells are connected in an embodiment of the present invention.

[0067] Figure label:

[0068] 10-First edge, 11-First region, 12-Second region, 13-Third edge; 2-First passivated contact structure, 20-First hollowed-out region, 21-Second hollowed-out region, 22-Third sub-hollowed-out region, 23-Second sub-hollowed-out region, 24-Third hollowed-out region, 25-Sixth hollowed-out region; 3-First bus electrode, 30-First bus electrode connecting line, 31-First end pad, 320-First sub-bus electrode; 4-First current collector electrode; 5-Conductive connector, 50-First connecting segment, 51-Second connecting segment, 52-Third connecting segment, 53-First end segment, 54-Second end segment, 55-Third end segment, 56-Fourth end segment; 6-First solar cell, 7-Second solar cell. Detailed Implementation

[0069] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention 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 invention and are not intended to limit the present invention.

[0070] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0071] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0072] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0073] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0074] To address the aforementioned technical problems, in a first aspect, the present invention provides a solar cell. (See also...) Figures 1 to 3 The solar cell includes a semiconductor substrate, a first passivation contact structure 2, a first bus electrode 3, and a first current collector 4. The semiconductor substrate includes opposing first and second surfaces; along a first direction A, the semiconductor substrate includes opposing first and second edges; the first passivation contact structure 2 is formed on the first surface of the semiconductor substrate; the first current collector 4 is formed above the first passivation contact structure 2; a plurality of first current collectors 4 extend along a second direction B and are spaced apart along the first direction A. The first bus electrode 3 is formed above the first passivation contact structure 2; the first bus electrode 3 intersects with the plurality of first current collectors 4. At least a portion of the first bus electrode 3 includes a first end pad 31 near the first edge 10 and a first end bus electrode connected to the first end pad 31, the first end bus electrode being located between the first end pad 31 and the first edge 10. The first end bus electrode includes at least two first sub-bus electrodes 320; the region between the two outermost first sub-bus electrodes 320 constitutes the first end bus electrode region. The first passivation contact structure 2 has a first hollow region 20 and a second hollow region 21; the first hollow region 20 is located within the first end bus electrode region; the second hollow region 21 is located outside the first end bus electrode region and between the first current collectors 4. It should be noted that, along the thickness direction of the solar cell, the entire area covered by the projection of the region between the two outermost first sub-bus electrodes 320 onto the semiconductor substrate is considered the first end bus electrode region. For example, in the first passivation contact structure, along the thickness direction of the solar cell, the area covered by the projection of the region between the two outermost first sub-bus electrodes 320 onto the semiconductor substrate is also referred to as the first end bus electrode region.

[0075] See Figures 1 to 3In the solar cell provided by this embodiment of the invention, the first bus electrode 3 is formed above the first passivation contact structure 2. The first bus electrode 3 is not in direct contact with the semiconductor substrate. This reduces metal recombination in the solar cell, increases the open-circuit voltage, and thus improves the cell efficiency. Furthermore, since the first current collector 4 is formed above the first passivation contact structure 2 and is electrically connected to it, good ohmic contact is ensured, contact resistivity is reduced, and series resistance is decreased to effectively collect current, reduce electrical losses, and improve the cell efficiency. Simultaneously, the carrier transport distance is reduced to minimize recombination losses during transport. Further, the first passivation contact structure 2 has a first hollow region 20 and a second hollow region 21. The first hollow region 20 is located within the first end bus electrode region; the second hollow region 21 is located outside the first end bus electrode region and between the first current collectors 4. That is, both the first hollow region 20 and the second hollow region 21 are formed within the non-metallic paste region of the solar cell. This application achieves dual optimization of optical and electrical performance by introducing a first hollow region 20 in the first end busbar electrode region. This design firstly significantly improves the effective utilization rate of incident light by reducing light absorption losses in the power generation area of ​​the cell, enabling more photons to participate in the photoelectric conversion process. More importantly, the first hollow region 20 in the first end busbar electrode region solves the current collection mismatch problem existing in the prior art, namely, the phenomenon of low collection efficiency of photogenerated carriers in some areas due to uneven electric field distribution inside the cell. By matching the first hollow region 20 in the first end busbar electrode region with the second hollow region 21 outside the first end busbar electrode region, not only is the effective collection efficiency of carriers in the electrode region significantly improved, but non-radiative recombination losses are also effectively suppressed. This improves key performance parameters such as fill factor (FF) and open-circuit voltage (Voc) while increasing the short-circuit current (Jsc), ultimately achieving a significant improvement in the overall conversion efficiency of the solar cell.

[0076] As one possible implementation, the first and second directions described above can be any two different directions parallel to the surface of the semiconductor substrate. See also: Figures 1 to 3 The first direction A and the second direction B are orthogonal.

[0077] As one possible implementation, the first side is the backlight side of the solar cell, and the second side is the light-receiving side of the solar cell.

[0078] As one possible implementation, the aforementioned solar cell could be a TOPCon cell.

[0079] In practical applications, the specific structure of the aforementioned solar cell can be determined according to the actual application scenario, and no specific limitations are made here. For example, the aforementioned semiconductor substrate can simply be a semiconductor substrate. For instance, the aforementioned semiconductor substrate can be a silicon substrate. In terms of conductivity type, the semiconductor substrate can be an N-type conductive substrate or a P-type conductive substrate. Preferably, the semiconductor substrate is an N-type conductive substrate. N-type conductive substrates have significant advantages over traditional P-type conductive substrates, mainly in terms of longer carrier lifetime, improved efficiency, attenuation control, and long-term reliability, which helps to reduce the series resistance of the solar cell and improve the efficiency of the solar cell. In terms of structure, the first surface of the semiconductor substrate can be textured to improve the light-trapping effect of the light-facing surface of the solar cell, thereby improving the utilization rate of light by the solar cell. Of course, the first surface of the semiconductor substrate can also be polished. As for the second surface of the semiconductor substrate, it can be polished or textured, and no specific limitations are made here.

[0080] In one implementation, see Figures 1 to 3 At least part of the first bus electrode 3 also includes: a first bus electrode connecting line 30, a plurality of first bus electrode connecting lines 30 extending along a first direction A and distributed at intervals along a second direction B; a first end pad 31 is disposed at one end of the first bus electrode connecting line 30 near the first edge 10.

[0081] See Figures 1 to 3 In the metallization process of solar cells, burn-through paste penetrates the passivation layer through high-temperature sintering, resulting in low contact resistance but potentially damaging the passivation layer; while non-burn-through paste requires laser grooving, resulting in an intact passivation layer and low recombination loss. The paste used to form the first current collector 4 is a burn-through paste. Optionally, the first current collector 4 can also use a non-burn-through paste to achieve an ultra-fine first current collector electrode (<20μm) and reduce light shading; for the first bus electrode 3, burn-through paste is suitable for high current transmission, while non-burn-through paste is suitable for multi-busbar (MBB) and low-temperature processes. As one possible implementation, the pastes used to form the first bus electrode connection line 30, the first end pad 31, and the first end bus electrode are all non-burn-through pastes, and the specific paste materials used for the three can be the same or different. In some embodiments, the paste materials used to form the first bus electrode connection line 30, the first end pad 31, and the first end bus electrode are the same, allowing for simultaneous printing, simplifying the process, and reducing costs.

[0082] As one possible implementation, see Figures 1 to 3The first passivated contact structure 2 described above can be composed of a P-type doped conductive semiconductor layer and a tunneling layer, or it can be composed of an N-type doped conductive semiconductor layer and a tunneling layer. The tunneling layer can generate a tunneling effect. More specifically, the tunneling layer can act as a barrier for electrons and holes. That is, the tunneling layer can prevent the transmission of minority carriers. After minority carriers accumulate in the portion adjacent to the tunneling layer, only majority carriers with a specific level or higher of energy can pass through the tunneling layer. Majority carriers with a specific level or higher of energy can easily pass through the tunneling layer. Furthermore, the tunneling layer can also serve as a diffusion barrier to prevent the diffusion of dopants from the N-type or P-type doped conductive semiconductor layer into the semiconductor substrate. The tunneling layer can include various materials through which majority carriers can tunnel. For example, the tunneling layer can include oxides, nitrides, semiconductors, and conductive polymers.

[0083] Specifically, the tunneling layer can be formed of a silicon oxide layer, including silicon oxide (SiOx). This is because silicon oxide layers have excellent passivation properties, and charge carriers can easily tunnel through the silicon oxide layer.

[0084] In some embodiments, the tunneling layer can be made of a dielectric material including SiCx, which exhibits strong durability even during high-temperature processing, or it can be made of SiNx, hydrogenated SiNx, AlOx, SiON, or hydrogenated SiON. The tunneling layer is formed on a semiconductor substrate, and an N-type doped conductive semiconductor layer or a P-type doped conductive semiconductor layer is formed on the tunneling layer. The N-type doped conductive semiconductor layer or the P-type doped conductive semiconductor layer is formed by doping amorphous silicon, microcrystalline silicon, or polycrystalline silicon with impurities of different conductivity types. This structure not only effectively passivates the dangling bonds on the silicon surface but also provides an electric field, allowing majority carriers to form a current and preventing minority carriers from moving to the surface and recombinating. Furthermore, the metal recombination at the metal-semiconductor contact is minimal, thus improving the passivation effect of the solar cell. Further, the improved passivation effect can significantly increase the open-circuit voltage of the solar cell, thereby improving cell efficiency.

[0085] Based on the preceding description, see [link / reference]. Figures 1 to 3 When the first passivated contact structure 2 has a first hollow region 20 and a second hollow region 21, part of the doped conductive semiconductor layer and the tunneling layer corresponding to the doped conductive semiconductor layer are removed. This reduces the absorption of near-infrared light by the doped conductive semiconductor layer, reduces light energy loss, allows more photons to be transferred to the semiconductor substrate, improves photoelectric conversion efficiency, increases bifaciality, and enhances the power generation capacity of the solar cell. Furthermore, removing part of the doped conductive semiconductor layer can reduce the doping recombination effect, improve carrier lifetime, and optimize the open-circuit voltage (Voc).

[0086] See Figures 1 to 3 For metal recombination losses, the metal-semiconductor contact is not a simple metal-semiconductor connection, but rather the formation of a gold semi-alloy. During the alloy formation process, in addition to the alloy itself, some scattered metal powder remains free in the semiconductor. This state of metal in the semiconductor belongs to deep-level impurities, does not participate in conductivity, and simultaneously acts as recombination centers, capturing electrons transported from the valence band to the conduction band, thus causing very severe metal recombination. Because the first passivation contact structure 2 has a high doping concentration, it can form alloys with a large amount of metal, resulting in fewer free metal particles. Furthermore, because the first passivation contact structure 2 has a doped conductive semiconductor layer and a tunneling layer, the metal generally does not penetrate the tunneling layer to contact the semiconductor substrate, thus reducing metal recombination.

[0087] See Figures 1 to 3 For ease of description, the first passivation contact structure 2 directly below the first bus electrode 3 is defined as the first sub-passivation contact structure, and the first passivation contact structure 2 directly below the first collector electrode 4 is defined as the second sub-passivation contact structure. Besides serving as a passivating surface, the first sub-passivation contact structure also needs to collect the current collected by the first collector electrode 4. Since the metal used in the solar cells of this embodiment is generally a metal paste, the metal material used is mostly metal powder. These metal powders have a certain particle size, making them prone to downward corrosion during the formation of the metal-semiconductor alloy. Therefore, the first sub-passivation contact structure needs to have a certain thickness to prevent the metal from burning through and directly contacting the semiconductor substrate. Thus, the first sub-passivation contact structure needs to have a certain thickness to act as a barrier, reducing metal recombination. Furthermore, the main function of the first sub-passivation contact structures other than the one directly below the first bus electrode 3 is to assist the second sub-passivation contact structure in collecting current, reducing the carrier transport distance, and thus reducing recombination losses. However, due to the strong parasitic absorption of the first sub-passivation contact structure (i.e., when light passes through the first sub-passivation contact structure, most of the light energy is absorbed by the first sub-passivation contact structure, and no large number of photogenerated carriers are generated at the PN junction, resulting in significant ineffective absorption and thus current loss), a thicker first sub-passivation contact structure will lead to a decrease in current.

[0088] See Figures 1 to 3For the overall solar cell, the shading area of ​​the first passivation contact structure 2 cannot be too large, as this would reduce the absorption of light by the entire solar cell and reduce the generation of photogenerated carriers. However, the photogenerated carriers generated by the entire solar cell need to be collected. Therefore, considering the photogenerated carrier collection efficiency, the first passivation contact structure 2 should cover the entire surface as much as possible. However, the disadvantages of the first passivation contact structure 2 in shading must be considered, and the entire surface cannot be completely blocked. Taking all factors into account, a first hollow area 20 and a second hollow area 21 are formed on the first passivation contact structure 2, so that the remaining first passivation contact structures 2 are connected into a mesh, which avoids excessive shading and ensures current collection. At the same time, the good passivation effect of the first passivation contact structure 2 improves the passivation effect of the entire solar cell. However, if the area of ​​the first passivation contact structure 2 is too small, the current collection path will be longer, the series connection will be larger, and the recombination loss will be increased. A higher doping concentration of the first passivation contact structure 2 is conducive to the formation of good gold-semiconductor contacts, while a lower doping concentration is conducive to reducing recombination. Therefore, it is necessary to comprehensively consider the area ratio and doping concentration of the first passivation contact structure 2, so as to take into account the open-circuit voltage, short-circuit current and fill factor of the solar cell, in order to form a cell structure with high efficiency.

[0089] As one possible implementation, see Figure 2 The widths of the first hollow area 20 and the second hollow area 21 are equal in the first direction A; the first hollow area 20 has a first center line O extending along the second direction B; along the second direction B, the second hollow area 21 adjacent to the first hollow area 20 has a second center line P extending along the second direction B.

[0090] The relative positional relationship between the first centerline and the second centerline mentioned above can be:

[0091] Example 1: See Figure 2 The first center line O and the second center line P are collinear.

[0092] See Figure 2 Because the first current collector electrode 4 is fabricated using a burn-through paste, this paste can easily cause metal to reach the semiconductor substrate, leading to increased metal recombination. To avoid this, in this application, the first center line O and the second center line P are collinear. This ensures a safe distance between the first hollowed-out area 20 and the second hollowed-out area 21 and the first current collector electrode 4 located on both sides of the first hollowed-out area 20 and the second hollowed-out area 21. This prevents the first hollowed-out area 20 and the second hollowed-out area 21 from being too close to the first current collector electrode 4, thus avoiding the generation of carrier recombination centers and metal recombination. This increases the open-circuit voltage of the solar cell, improves the short-circuit current and fill factor, reduces contact resistance, and ultimately improves the cell efficiency of the solar cell.

[0093] Example 2: See Figure 2 Along the first direction A, the ratio of the distance between the first center line O and the second center line P to the width of the first hollow area 20 along the first direction A or to the width of the second hollow area 21 along the first direction A is less than or equal to 10%. For example, the ratio can be 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1%, etc.

[0094] Example 3: See Figure 2 When the first passivated contact structure 2 has multiple first hollow areas 20 and multiple second hollow areas 21, the first center line O and the second center line P are collinear at the same time; and the ratio of the distance between the first center line O and the second center line P along the first direction A to the width of the first hollow area 20 along the first direction A or the width of the second hollow area 21 along the first direction A is less than or equal to 10%.

[0095] See Figure 2 The first hollowed-out region 20 and the second hollowed-out region 21 are formed after laser processing of the first passivated contact structure 2. If the ratio is greater than 10%, it indicates that during the laser processing of the first passivated contact structure 2, the offset of the first hollowed-out region 20 relative to the second hollowed-out region 21 in the first direction A is too large, or the offset of the second hollowed-out region 21 relative to the first hollowed-out region 20 in the first direction A is too large. In this case, it is very easy for the first hollowed-out region 20 or the second hollowed-out region 21 to be located below the first collector electrode 4, causing the first passivated contact structure 2 corresponding to the first collector electrode 4 to be broken. That is, it is easy for the laser to remove part of the first passivated contact structure 2 corresponding to the first collector electrode 4, resulting in the first collector electrode 4 being directly welded to the semiconductor substrate when it is subsequently formed, generating carrier recombination centers and metal recombination, reducing the short-circuit current and fill factor of the solar cell, and increasing the contact resistance. In summary, when the ratio of the distance between the first center line O and the second center line P to the width of the first hollow area 20 along the first direction A or the width of the second hollow area 21 along the first direction A is less than or equal to 10%, the first collector electrode 4 can be prevented from being directly welded to the semiconductor substrate, thus avoiding the generation of carrier recombination centers and metal recombination. This increases the open-circuit voltage of the solar cell, improves the short-circuit current and fill factor of the solar cell, reduces the contact resistance, and thereby improves the cell efficiency of the solar cell.

[0096] As one possible implementation, see Figure 2 The first end busbar region has multiple first hollow regions 20 that are spaced apart along the first direction A.

[0097] See Figure 2At this point, not only can the shading of the semiconductor substrate by the first passivation contact structure 2 be effectively reduced, and the parasitic absorption of light by the first passivation contact structure 2 be reduced, but the light absorption loss in the power generation area of ​​the solar cell can also be reduced, thus reducing light energy loss and significantly improving the effective utilization rate of incident light. This allows more photons to be transferred to the semiconductor substrate, enabling more photons to participate in the photoelectric conversion process and improving the photoelectric conversion efficiency of the solar cell. Simultaneously, it can also increase the carrier generation rate in the first end current collector electrode region, reduce the recombination rate, and reduce current collection mismatch. Furthermore, it further solves the current collection mismatch problem existing in the prior art.

[0098] In some embodiments, see Figure 2 The two adjacent first hollow areas 20 are staggered in the first direction A.

[0099] See Figure 2 When the above technical solution is adopted, if the first hollow area 20 is opened on the first passivated contact structure 2, the first hollow area 20 will disrupt the original stress distribution, and stress concentration is likely to occur at the edge of the first hollow area 20. When two adjacent first hollow areas 20 are staggered in the first direction A, the stress can be dispersed to different directions, avoiding the overlap of stress concentration areas and reducing the risk of local fracture. Furthermore, it can reduce the probability of the first passivated contact structure 2 below the first current collector 4 and the first bus electrode 3 fractured due to stress concentration when the first current collector 4 and the first bus electrode 3 are subsequently fabricated on the first passivated contact structure 2 with the first hollow area 20, thereby reducing or avoiding the generation of carrier recombination centers and metal recombination, increasing the open-circuit voltage of the solar cell, improving the short-circuit current and fill factor of the solar cell, and thus improving the cell efficiency of the solar cell. Furthermore, the staggered arrangement of two adjacent first hollow areas 20 in the first direction A can disperse processing errors, avoid the cumulative errors during processing causing the positional deviations of all the first hollow areas 20 to overlap along the first direction A, thereby preventing processing errors from exceeding design errors, improving the fault tolerance rate, and thus improving the quality of solar cells.

[0100] As one possible implementation, see Figure 2 The distance between the two second cutout areas 21 located on both sides of the first end pad 31 along the second direction B is L1, and the distance between the two second cutout areas 21 located on both sides of the first bus electrode connection line 30 along the second direction B is L2, satisfying that L1 is greater than L2.

[0101] See Figure 2By adopting the above technical solution, the removal of the first passivation contact structure 2 corresponding to the first end pad 31 can be reduced or avoided when forming the two second hollow areas 21 located on both sides of the first end pad 31 along the second direction B, thereby reducing or avoiding direct contact between the first end pad 31 and the semiconductor substrate below it. This not only reduces or avoids the formation of recombination centers, improving minority carrier lifetime and battery open-circuit voltage, but also reduces contact resistance and improves current collection efficiency.

[0102] As one possible implementation, see Figure 2 Along the second direction B, the distances between the two second hollowed-out areas 21 located on both sides of the first busbar connection line 30 and the first busbar connection line 30 are not equal.

[0103] See Figure 2 In the subsequent formation of photovoltaic modules, conductive connectors 5 such as solder strips are welded to the connection line of the first busbar electrode 3. Since the distance between the two second hollow areas 21 located on both sides of the first busbar electrode connection line 30 along the second direction B in this application is not equal to the distance between the first busbar electrode connection line 30 and the second hollow area 21, stress concentration can be reduced and the mechanical strength of the conductive connectors 5 such as solder strips can be improved during welding.

[0104] For example, the two distances between the two second hollowed-out areas 21 located on both sides of the first bus electrode connection line 30 and the first bus electrode connection line 30 are L3 and L4, respectively, and L3 and L4 are not equal.

[0105] As one possible implementation, see Figure 1 Along the second direction B, the distance between the first hollow area 20 and the adjacent second hollow area 21 is L5, and the distance between two adjacent first hollow areas 20 along the first direction A is L6, satisfying that L5 is greater than L6.

[0106] See Figure 1In the case of the above technical solution, the first passivation contact structure 2 between the second hollow area 21 adjacent to the first hollow area 20 and the first hollow area 20 corresponds to the first sub-bus electrode 320, and the first passivation contact structure 2 between two adjacent first hollow areas 20 corresponds to the first current collector electrode 4. Since the contact performance between the first bus electrode and the solar cell is lower than that of the first current collector electrode 4; or, since the first bus electrode needs to be welded to conductive connectors 5 such as solder strips, the contact area with the solar cell surface or conductive connector 5 is usually increased by increasing the width of the first bus electrode to improve its contact and welding performance. Furthermore, since the first bus electrode includes the first sub-bus electrode 320, the width of the first sub-bus electrode 320 is relatively wide. Based on this, in this application, L5 is greater than L6. Further, since the paste forming the first bus electrode has high ductility, the width of the first bus electrode is greater than the width of the first current collector electrode 4, that is, the width of the first sub-bus electrode 320 is greater than the width of the first current collector electrode 4. Based on this, in this application, L5 is greater than L6 to improve the fault tolerance of the printing offset of the first sub-bus electrode 320. In addition, the above solution can also reduce the parasitic absorption of light by the first passivation contact structure 2 between two adjacent first hollow areas 20, thereby improving the light utilization rate.

[0107] In one alternative approach, see Figure 1 Along the second direction B, the distance L5 between the first hollowed-out area 20 and the adjacent second hollowed-out area 21 is greater than or equal to 50 μm and less than or equal to 1.5 mm. For example, the above distance can be 50 μm, 80 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, 800 μm, 850 μm, 900 μm, 950 μm, 1000 μm, 1100 μm, 1200 μm, 1300 μm, 1400 μm, or 1500 μm, etc.

[0108] When the above technical solution is adopted, when L5 is greater than or equal to 50 μm, along the second direction B, the width of the first passivation contact structure 2 between the second hollow region 21 adjacent to the first hollow region 20 and the first hollow region 20 is greater than or equal to 50 μm. This width of the first passivation contact structure 2 provides sufficient space for the subsequent formation of the first sub-bus electrode 320 at the corresponding position above it, ensuring that the width of the corresponding first sub-bus electrode 320 above the first passivation contact structure 2 meets actual needs. Furthermore, if along the second direction B, the width of the first passivation contact structure 2 between the second hollow region 21 adjacent to the first hollow region 20 and the first hollow region 20 is less than 50 μm, the first conductive contact layer cannot effectively collect current and is easily removed during cleaning. When L5 is less than or equal to 1.5mm, along the second direction B, the width of the first passivation contact structure 2 between the second hollow area 21 adjacent to the first hollow area 20 and the first hollow area 20 is less than or equal to 1.5mm. By controlling the size of the first passivation contact structure 2 at this position, the parasitic absorption of light by the first passivation contact structure 2 is reduced, the light absorption loss in the power generation area of ​​the solar cell is reduced, the light energy loss is reduced, the effective utilization rate of incident light is significantly improved, and more photons can be transmitted to the semiconductor substrate, so that more photons can participate in the photoelectric conversion process and improve the photoelectric conversion efficiency of the solar cell.

[0109] In one alternative approach, see Figure 1 The distance L6 between two adjacent first hollow areas 20 along the first direction A is greater than or equal to 50μm and less than or equal to 1mm. For example, the above distance can be 50μm, 80μm, 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm, 500μm, 550μm, 600μm, 650μm, 700μm, 750μm, 800μm, 850μm, 900μm, 950μm, or 1000μm, etc.

[0110] When the above technical solution is adopted, when L6 is greater than or equal to 50 μm, the width of the first passivation contact structure 2 between two adjacent first hollow areas 20 is greater than or equal to 50 μm. The width of the first passivation contact structure 2 provides sufficient space for the subsequent formation of the first current collector 4 at the corresponding position above it, ensuring that the width of the first current collector 4 above the first passivation contact structure 2 meets the actual needs. When L6 is less than or equal to 1 mm, the width of the first passivation contact structure 2 between two adjacent first hollow areas 20 is less than or equal to 1 mm. By controlling the size of the first passivation contact structure 2 at this position, the parasitic absorption of light by the first passivation contact structure 2 is reduced, the light utilization rate is improved, and thus the photoelectric conversion efficiency of the solar cell is improved.

[0111] As one possible implementation, see Figure 1 and Figure 3 The portion of the first collector electrode 4 adjacent to the first edge 10 is disconnected at the first end bus electrode region, and the first passivation contact structure 2 corresponding to the first collector electrode 4 extends through the first end bus electrode region along the extension direction of the first collector electrode 4. That is, below the disconnected, non-existent first collector electrode 4, there is a first passivation contact structure 2 extending through the first end bus electrode region along the extension direction of the first collector electrode 4.

[0112] See Figure 1 and Figure 3 By adopting the above technical solution, the impact of welding of the first current collector 4 with conductive connectors such as solder strips on the first end busbar region can be reduced, minimizing or avoiding the number of damaged first current collector 4s. In particular, the first current collector 4 located in the first end busbar region, and in a portion adjacent to the first edge 10, experiences greater pressure from the conductive connectors such as solder strips after being connected to them, making it more prone to welding failure and even damaging the first passivation contact structure 2 at that location. Therefore, in this application, a portion of the first current collector 4 adjacent to the first edge 10 is disconnected in the first end busbar region.

[0113] Further, see Figure 1 and Figure 3 Because the first current collector electrode 4 near the first edge 10 is disconnected at the first end busbar region, there is a blank area in the first end busbar region, particularly near the first edge 10, where the first current collector electrode 4 is absent. During subsequent photovoltaic module manufacturing, the bent portion of the conductive connector 5 (such as the solder ribbon) utilizes this blank area to connect with other solar cells. This reduces or avoids microcracks or fragmentation of the solar cells due to the elevation of the first current collector electrode 4, and lowers the height difference between the conductive connector 5 to be welded to the first side of the first solar cell and the conductive connector 5 to be welded to the second side of the second solar cell, thereby improving the yield of the cell string and solar module. Furthermore, the first passivated contact structure 2 corresponding to the first current collector electrode 4 extends through the first end busbar region along the direction of the first current collector electrode 4. This enhances the mechanical strength of the solar cell edge and provides a transport channel for charge carriers. Charge carriers can be collected and transported through the penetrating first passivated contact structure 2, improving short-circuit current and cell efficiency.

[0114] As one possible implementation, see Figure 1 and Figure 3 The number of first collector electrodes 4 that are adjacent to the first edge 10 and disconnected at the first end bus electrode region is less than or equal to 5.

[0115] When using the above technical solution, see Figure 1 and Figure 3 While ensuring a certain size of blank area, it is also necessary to ensure that the number of first current collector electrodes 4 included in the first end current collector electrode area meets the actual needs, so as to take into account the cell efficiency of the solar cell.

[0116] As one possible implementation, see Figure 2 The size of the first cutout area closest to the first end pad 31 (defined as the third sub-cutout area 22 for easy identification) is smaller than the size of the first cutout area 20 far from the first end pad 31.

[0117] In one alternative approach, see Figure 2 The first cutout region 20 (i.e., the third sub-cutout region 22) which is closest to the first end pad 31 is closer to the first collector electrode 4 located in the first end bus electrode region than the first end pad 31.

[0118] When using the above technical solution, see Figure 2 This reduces or avoids the probability that the first passivated contact structure 2 below the first end pad 31 will be removed when forming the first cutout region 20 closest to the first end pad 31, thereby reducing or avoiding direct contact between the first end pad 31 and the semiconductor substrate below it. This not only reduces or avoids the formation of recombination centers, improving minority carrier lifetime and battery open-circuit voltage, but also reduces contact resistance and improves current collection efficiency.

[0119] As another possible implementation, see Figures 1 to 3 Remove the first cutout area 20 closest to the first end pad 31 (i.e., do not create the first cutout area 20 closest to the first end pad 31, in other words, do not create the attached area). Figure 2 The third sub-cutout area 22) is used to completely prevent the first passivation contact structure 2 below the first end pad 31 from being removed when the first cutout area 20 closest to the first end pad 31 is formed.

[0120] As one possible implementation, see Figures 1 to 3The size of the second cutout region 21 located circumferentially around the first end pad 31 is smaller than the size of the second cutout region 21 located away from the first end pad 31, and the second cutout region 21 located circumferentially around the first end pad 31 is located away from the first end pad 31. That is, the small-sized second cutout region 21 located circumferentially around the first end pad 31 is formed at a position away from the first end pad 31 to reduce or avoid the probability that the first passivation contact structure 2 below the first end pad 31 will be removed when forming the second cutout region 21 located circumferentially around the first end pad 31, thereby reducing or avoiding direct contact between the first end pad 31 and the semiconductor substrate below it. At this time, not only can the generation of recombination centers be reduced or avoided, improving minority carrier lifetime and battery open-circuit voltage, but also the contact resistance can be reduced, improving current collection efficiency.

[0121] As another possible implementation, see Figures 1 to 3 The second cutout area 21 located around the first end pad 31 is removed (i.e., the second cutout area 21 located around the first end pad 31 is not formed) to completely avoid the removal of the first passivation contact structure 2 below the first end pad 31 when the second cutout area 21 located around the first end pad 31 is formed.

[0122] As one possible implementation, see Figures 1 to 3 The solar cell also includes: connecting pads. Multiple connecting pads are spaced apart along the first direction A on the first bus electrode connection line 30.

[0123] As one possible implementation, see Figures 1 to 3 The length of the second cutout region 21 located circumferentially to the connecting pad along the second direction B is less than the length of the second cutout region 21 located away from the connecting pad along the second direction B. In some embodiments, the second cutout region 21 located circumferentially to the connecting pad is located away from the connecting pad. That is, the small-sized second cutout region 21 located circumferentially to the connecting pad is formed at a position away from the connecting pad to reduce or avoid the probability that the corresponding first passivation contact structure 2 below the connecting pad is removed when forming the second cutout region 21 located circumferentially to the connecting pad, thereby reducing or avoiding direct contact between the connecting pad and the semiconductor substrate below it. At this time, not only can the generation of recombination centers be reduced or avoided, improving minority carrier lifetime and battery open-circuit voltage, but also the contact resistance can be reduced, improving current collection efficiency.

[0124] As another possible implementation, see Figures 1 to 3 The second cutout area 21 located around the connection pad is removed (i.e., the second cutout area 21 located around the connection pad is not formed) to completely avoid the removal of the corresponding first passivation contact structure 2 below the connection pad when the second cutout area 21 located around the connection pad is formed.

[0125] As one possible implementation, see Figure 2 The distance between the first hollowed-out region 20 and the first sub-bus electrode 320 is greater than the distance between the first hollowed-out region 20 and the first collector electrode 4. It should be noted that the distance between the first hollowed-out region 20 and the first sub-bus electrode 320 can be any distance between them, such as the minimum distance, the maximum distance, or the distance between the first sub-bus electrode 320 and the center line of the first hollowed-out region 20 along the first direction A.

[0126] See Figure 2 When the above technical solution is adopted, the function of the first collector electrode 4 is to collect charge carriers. The closer the first hollow region 20 is to the first collector electrode 4, the more charge carriers are generated around the first collector electrode 4 due to the reduction of parasitic light absorption, and the more charge carriers are collected, which is beneficial to increasing the number of charge carriers. The first sub-collector electrode 320 is used to collect and transmit the current on the first collector electrode 4. It is not responsible for collecting charge carriers itself. Maintaining a large safety distance can improve the reliability of solar energy and accommodate process errors.

[0127] As one possible implementation, see Figure 2 The distance between the first hollowed-out area 20 and the first sub-bus electrode 320 is greater than or equal to 50 μm and less than or equal to 1.5 mm. For example, the above distance can be 50 μm, 80 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, 800 μm, 850 μm, 900 μm, 950 μm, 1000 μm, 1100 μm, 1200 μm, 1300 μm, 1400 μm or 1500 μm, etc.

[0128] When using the above technical solution, see Figure 2 The first sub-bus electrode 320 is used to collect and transmit the current on the first collector electrode 4, but it is not responsible for collecting charge carriers itself. When the distance between the first hollowed-out region 20 and the first sub-bus electrode 320 is within the above-mentioned range, a larger safe distance is maintained between the first hollowed-out region 20 and the first sub-bus electrode 320 to improve the reliability of solar energy and accommodate process errors.

[0129] As one possible implementation, see Figure 2The distance between the first hollowed-out area 20 and the first current collector 4 is greater than or equal to 50 μm and less than or equal to 1 mm. For example, the above distance can be 50 μm, 80 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, 800 μm, 850 μm, 900 μm, 950 μm or 1000 μm, etc.

[0130] When using the above technical solution, see Figure 2 The function of the first collector electrode 4 is to collect charge carriers. The closer the first hollow region 20 is to the first collector electrode 4, the more charge carriers are generated around the first collector electrode 4 due to the reduction of parasitic absorption of light, and the more charge carriers are collected, which is beneficial to increasing the number of charge carriers. Therefore, in this application, the distance between the first hollow region 20 and the first collector electrode 4 is set to be greater than or equal to 50 μm and less than or equal to 1 mm.

[0131] The shape of the first hollowed-out area is related to the shape of the first end busbar electrode area. The following description uses two possible cases as examples. It should be understood that the following description is for understanding only and is not intended to limit the specific situation.

[0132] First scenario: See [link / reference] Figures 1 to 3 For the same first end bus electrode, along the direction close to the first end pad 31, the spacing between the two outermost first sub-bus electrodes 320 is reduced, the length of the first cutout region 20 between two adjacent first sub-bus electrodes 320 is reduced, and the length direction of the first cutout region 20 is consistent with the second direction B.

[0133] See Figures 1 to 3 With the above technical solution, while ensuring that the first passivation contact structure 2 is present at the corresponding position below the first sub-current collector electrode 320 and the first current collector electrode 4, the area of ​​the first hollow area 20 is made larger to reduce the parasitic absorption of light by the first passivation contact structure 2, reduce the light absorption loss in the power generation area of ​​the cell, reduce light energy loss, significantly improve the effective utilization rate of incident light, and enable more photons to be transmitted to the semiconductor substrate, so that more photons can participate in the photoelectric conversion process and improve the photoelectric conversion efficiency of the solar cell.

[0134] For example, see Figures 1 to 3When the two outermost first sub-bus electrodes 320 extend along an oblique line (the oblique line has an angle with respect to the first direction A) and the distance between them decreases, the two short sides of the first hollow region 20 located between two adjacent first sub-bus electrodes 320 also extend along an oblique line and the distance between the two short sides decreases, thereby reducing the length of the first hollow region 20. Alternatively, when the two outermost first sub-bus electrodes 320 extend along an oblique line and the distance between them decreases, one short side of the first hollow region 20 located between two adjacent first sub-bus electrodes 320 extends along an oblique line, and the other short side extends along the first direction. In this case, the distance between the two short sides also decreases, thereby reducing the length of the first hollow region 20. Alternatively, when one of the two outermost first sub-bus electrodes 320 extends along an oblique line and the other extends along the first direction A, with the distance between them decreasing, one short side of the first hollow region 20 located between the two adjacent first sub-bus electrodes 320 extends along an oblique line, and the other short side extends along the first direction A. In this case, the distance between the two short sides also decreases, thereby reducing the length of the first hollow region 20. Alternatively, when one of the two outermost first sub-bus electrodes 320 extends along an oblique line and the other extends along the first direction A, with the distance between them decreasing, both short sides of the first hollow region 20 located between the two adjacent first sub-bus electrodes 320 extend along oblique lines, and the distance between the two short sides decreases, thereby reducing the length of the first hollow region 20.

[0135] Second scenario: See Figures 1 to 3 For the same first end bus electrode, any two adjacent first sub-bus electrodes 320 are parallel to each other; along the first direction A, the length of the first hollow region 20 located between two adjacent first sub-bus electrodes 320 remains unchanged, and the length direction of the first hollow region 20 is consistent with the second direction B.

[0136] For example, see Figure 2For the same first end bus electrode, any two adjacent first sub-bus electrodes 320 extend along the first direction A; along the first direction A, the two short sides of the first hollow region 20 located between two adjacent first sub-bus electrodes 320 also extend along the first direction A, so that the length of the first hollow region 20 remains unchanged. Alternatively, for the same first end bus electrode, any two adjacent first sub-bus electrodes 320 extend along a diagonal line (the diagonal line has an angle with respect to the first direction A), and the two are parallel to each other; along the first direction A, the two short sides of the first hollow region 20 located between two adjacent first sub-bus electrodes 320 also extend along a diagonal line, and the two short sides are parallel to each other, so that the length of the first hollow region 20 remains unchanged. Further, the extension direction of the two short sides of the first hollow region 20 is consistent with the extension direction of the first sub-bus electrode.

[0137] In some embodiments, see Figure 2 For the same first end bus electrode, any two adjacent first sub-bus electrodes 320 are parallel to each other; along the first direction A, the length of the first hollow region 20 located between two adjacent first sub-bus electrodes 320 remains unchanged, and the length direction of the first hollow region 20 is consistent with the second direction B. Furthermore, at least one short side of the first hollow region 20 located between two adjacent first sub-bus electrodes 320 is parallel to the first sub-bus electrode 320.

[0138] It should be noted that the first and second cases described above do not limit the number of first sub-bus electrodes 320 included in the first end bus electrode.

[0139] As one possible implementation, see Figure 4 The second hollowed-out area 21 includes multiple second sub-hollowed-out areas 23. Along the second direction B, the multiple second sub-hollowed-out areas 23 are spaced apart; and / or, see... Figure 1 Along the second direction B, multiple second sub-hollow areas 23 abut together.

[0140] When using the above technical solution, see Figure 1 and Figure 4In the actual formation of the second hollow region 21, the first passivated contact structure 2 is processed by laser. The laser spots formed during the laser processing are arranged along the second direction B. When two adjacent laser spots overlap or abut, two adjacent second sub-hollow regions 23 overlap or abut along the second direction B. When two adjacent laser spots are spaced apart, two adjacent second sub-hollow regions 23 are spaced apart along the second direction B. Therefore, the method of forming the second hollow region 21 can be selected according to actual needs, increasing the application scenarios of solar cells and expanding their applicability. Furthermore, when multiple second sub-hollow regions 23 are spaced apart along the second direction B, there is a first passivated contact structure 2 between adjacent second sub-hollow regions 23. This first passivated contact structure 2 facilitates the transport of charge carriers, which are transported to the first current collector 4 through this first passivated contact structure 2, thereby improving the current collection capability of the solar cell.

[0141] As one possible implementation, see Figure 1 The first surface of the semiconductor substrate includes a first region 11 and a second region 12 surrounding the first region 11; a first bus electrode 3 and a first collector electrode 4 are located within the first region 11; and a first passivation contact structure 2 is located within both the first region 11 and the second region 12.

[0142] As can be seen from the above, the second region 12 is located between the multiple edges of the semiconductor substrate and the first region 11. Since the first passivation contact structure 2 is formed in the second region 12 surrounding the first region 11, compared with the case where the first passivation contact structure 2 is not formed in the second region 12 surrounding the first region 11, this application can improve the mechanical strength of the second region 12 of the solar cell (i.e., the region near the edge in the solar cell) and reduce the breakage rate of the second region 12 of the solar cell.

[0143] In one alternative approach, see Figure 1 The first passivated contact structure 2 also has a third hollow region 24, which is located within the second region 12 and close to the first edge 10. This further reduces parasitic absorption of light by the first passivated contact structure 2, improves light utilization, and enhances the photoelectric conversion efficiency of the solar cell.

[0144] In one alternative approach, see Figure 1 Along the second direction B, the semiconductor substrate includes opposing third edges 13 and fourth edges. The first passivation contact structure 2 also includes at least one sixth hollow region 25, which is located within the second region 12 and near the third edge 13 and / or near the fourth edge. This further reduces parasitic absorption of light by the first passivation contact structure 2, improves light utilization, and enhances the photoelectric conversion efficiency of the solar cell.

[0145] In some embodiments, see Figure 1 The second hollow area 21 located on one side of the sixth hollow area 25 along the second direction B is on the same straight line as the sixth hollow area 25, and the second hollow area 21 located on one side of the sixth hollow area 25 along the second direction B is distributed at intervals with the sixth hollow area 25.

[0146] In other embodiments, see Figure 1 The first passivated contact structure 2 includes a plurality of sixth hollow areas 25, with two adjacent sixth hollow areas 25 spaced apart along the first direction A, and / or, two adjacent sixth hollow areas 25 abutting or overlapping along the first direction A.

[0147] As described above, see [link / reference] Figures 1 to 3 The first end bus electrode includes at least two first sub-bus electrodes 320 that extend along a first direction A and are spaced apart along a second direction B.

[0148] As one possible implementation, see Figure 1 The first end bus electrode includes two first sub-bus electrodes 320 that extend along a first direction A and are spaced apart along a second direction B.

[0149] As another possible implementation, see Figure 3 The first end bus electrode includes three first sub-bus electrodes 320 extending along a first direction A and spaced apart along a second direction B; the area between two adjacent first sub-bus electrodes 320 constitutes a first sub-end bus electrode area; each first sub-end bus electrode area has a first hollow area 20.

[0150] When using the above technical solution, see Figure 3 Compared to the prior art where there is only a first busbar connection line 30 and no first sub-busbar electrode 320, the present application increases the number of first sub-busbar electrodes 320 and reduces the area of ​​each first sub-busbar electrode 320 that collects charge carriers. This improves the ability of the first sub-busbar electrode 320 to collect charge carriers generated in that area, enhances its current collection ability, and makes the current collection more uniform. Furthermore, during the formation of the photovoltaic module, when the conductive connector 5 such as the solder ribbon is simultaneously connected to the first end pad 31 and the first sub-busbar electrode 320 located in the middle of the first end busbar electrode, compared to when the conductive connector 5 is only connected to the first end pad 31, the present application not only improves the speed of current transmission to the conductive connector 5 and the current collection ability of the conductive connector 5, reducing current transmission loss, but also improves the connection strength of the conductive connector 5 and increases the yield of the solar cell.

[0151] As one possible implementation, see Figures 1 to 3 The first bus electrode 3 further includes: a second end pad disposed along the first direction A in the first bus electrode connection line 30 near the second edge, and a second end bus electrode connected to the second end pad; the second end bus electrode includes at least two second sub-bus electrodes; the area between the two outermost second sub-bus electrodes constitutes the second end bus electrode area; the first hollow area 20 is also located within the second end bus electrode area; the second hollow area 21 is also located outside the second end bus electrode area and between the first collector electrodes. In this way, the parasitic absorption of light by the first passivation contact structure 2 is further reduced, improving light utilization and thus improving the photoelectric conversion efficiency of the solar cell.

[0152] See Figures 1 to 3 It should be noted that the descriptions of the second end pad, the second end bus electrode, and the second end bus electrode region can be found in the previous descriptions of the first end pad 31, the first end bus electrode, and the first end bus electrode region, and will not be repeated here.

[0153] As one possible implementation, the solar cell further includes: a second passivated contact structure, a second bus electrode, and a second current collector electrode. The second passivated contact structure is formed on the second surface of the semiconductor substrate; the second bus electrode is formed above the second passivated contact structure; and multiple second bus electrodes extend along a first direction and are spaced apart along a second direction. The second bus electrode includes a second bus electrode connecting line, a third end pad disposed along a first direction near the first edge of the second bus electrode connecting line, and a third end bus electrode connected to the third end pad; the third end bus electrode includes at least two third sub-bus electrodes extending along the first direction and spaced apart along the second direction; the area between the two outermost third sub-bus electrodes constitutes the third end bus electrode area; the second collector electrode is formed above the second passivation contact structure; multiple second collector electrodes extend along the second direction and are spaced apart along the first direction; the second bus electrode intersects with the multiple second collector electrodes; the second passivation contact structure has a fourth cutout area and a fifth cutout area; the fourth cutout area is located within the third end bus electrode area; the fifth cutout area is located outside the third end bus electrode area and between the second collector electrodes.

[0154] By adopting the above technical solution, this application achieves dual optimization of optical and electrical performance by introducing a fourth hollow region in the third end busbar electrode region. This design firstly significantly improves the effective utilization rate of incident light by reducing light absorption losses in the cell's power generation area, enabling more photons to participate in the photoelectric conversion process. More importantly, the fourth hollow region in the third end busbar electrode region solves the current collection mismatch problem existing in the prior art, namely, the phenomenon of low collection efficiency of photogenerated carriers in some areas due to uneven electric field distribution inside the cell. By matching the fourth hollow region in the third end busbar electrode region with the fifth hollow region outside the third end busbar electrode region, not only is the effective collection efficiency of carriers in the electrode region significantly improved, but non-radiative recombination losses are also effectively suppressed. This improves key performance parameters such as fill factor (FF) and open-circuit voltage (Voc) while increasing the short-circuit current (Jsc), ultimately achieving a significant improvement in the overall conversion efficiency of the solar cell. Furthermore, the combined effect of the first and second hollow regions in the first passivated contact structure, and the fourth and fifth hollow regions in the second passivated contact structure, improves the bifaciality of the solar cell. In addition, since the second current collector is formed above the second passivated contact structure and is electrically connected to it, this not only reduces contact resistivity and series resistance to effectively collect current, reduce electrical losses, and improve the cell efficiency of the solar cell, but also shortens the carrier transport distance, thereby reducing recombination losses during transport.

[0155] In one alternative embodiment, the second bus electrode further includes: a fourth end pad disposed along a first direction in the second bus electrode connection line near the second edge, and a fourth end bus electrode connected to the fourth end pad. The fourth end bus electrode includes at least two fourth sub-bus electrodes; the region between the two outermost fourth sub-bus electrodes constitutes the fourth end bus electrode region; a fourth hollow region is also located within the fourth end bus electrode region; a fifth hollow region is also located outside the fourth end bus electrode region and between the second current collector electrodes. This further reduces the parasitic absorption of light by the second passivated contact structure, improves light utilization, and thus improves the photoelectric conversion efficiency and bifaciality of the solar cell.

[0156] It should be noted that the descriptions of the second passivated contact structure, the second current collector electrode, the fourth cutout area, the fifth cutout area, the third end pad, the third end bus electrode, the third end bus electrode area, the fourth end pad, the fourth end bus electrode, and the fourth end bus electrode area can be found in the previous descriptions of the relevant structures located on the first surface of the solar cell, and will not be repeated here.

[0157] From the perspective of the first bus electrode, the solar cell in this application can be one of three types of solar cells. It should be understood that the following description is for comprehension only and is not intended to limit the application.

[0158] First type of solar cell: See Figures 1 to 3 All first bus electrodes 3 include: a first end pad 31 near the first edge 10 and a first end bus electrode connected to the first end pad 31.

[0159] The second type of solar cell: See [link] Figures 1 to 3 All first bus electrodes 3 include: a first bus electrode connection line 30, a first end pad 31 disposed in the first bus electrode connection line 30 near the first edge 10 along the first direction A, and a first end bus electrode connected to the first end pad 31.

[0160] The third type of solar cell: See [link] Figures 1 to 3 A portion of the first bus electrode 3 includes: a first bus electrode connecting line 30, a first end pad 31 disposed along the first direction A near the first edge 10 in the first bus electrode connecting line 30, and a first end bus electrode connected to the first end pad 31. Another portion of the first bus electrode 3 includes only the first end pad 31 near the first edge 10 and the first end bus electrode connected to the first end pad 31. The first bus electrodes 3 including the first bus electrode connecting line 30 and the first bus electrodes 3 excluding the first bus electrode connecting line 30 are alternately distributed along the second direction B. A second cutout region 21 is correspondingly provided at the location where the first bus electrode connecting line 30 is not formed.

[0161] In some embodiments, see Figures 1 to 3 A first passivation contact structure 2 is formed at the location where the first busbar connection line 30 is formed in the solar cell, and the location where the first busbar connection line 30 is not formed does not have the first passivation contact structure 2.

[0162] See Figures 1 to 3By adopting the above technical solution, the shading of the first bus electrode connection line 30 on the semiconductor substrate is reduced, allowing more light to reach the semiconductor substrate, increasing the generation of photogenerated carriers, and improving the short-circuit current and photoelectric conversion efficiency. Furthermore, the amount of paste used in fabricating the first bus electrode connection line 30 is reduced (e.g., the amount of silver paste is reduced), lowering the raw material cost of the first bus electrode 3, and consequently reducing the raw material cost of the solar cell. In addition, due to the significant difference in thermal expansion coefficients between the first bus electrode 3 and the semiconductor substrate, the first bus electrode 3 is prone to thermal mismatch stress with the semiconductor substrate during temperature changes, leading to microcracks in the semiconductor substrate. In this application, reducing the number of first bus electrode connection lines 30 can reduce the probability of microcracks in the semiconductor substrate and improve the yield of the solar cell.

[0163] Secondly, embodiments of the present invention also provide a photovoltaic module. See [link to related document]. Figure 4 The photovoltaic module includes a battery string and an encapsulation layer; the battery string includes multiple conductive connectors 5 and multiple solar cells as described in the above technical solution; the conductive connectors 5 connect the multiple solar cells in series; the encapsulation layer is used to cover the surface of the battery string.

[0164] The beneficial effects of the photovoltaic modules provided in the embodiments of the present invention are the same as those of the solar cells described in the above technical solutions, and will not be repeated here.

[0165] The aforementioned solar cell can be a TOPCon cell.

[0166] See Figure 4 The conductive connector 5 can be a solder strip or other connector used to connect solar cells. When the conductive connector 5 is a solder strip, the solder strip can be a circular, triangular, or rectangular solder strip. Preferably, a circular solder strip is used. This can help to cope with the mechanical stress at the connection of the solar cells, eliminate the problem of microcracks in high-density solar modules, and improve the reliability of the solar modules.

[0167] As one possible implementation, see Figures 1 to 4When a solar cell includes a first end pad 31, a second end pad, a third end pad, and a fourth end pad, multiple solar cells arranged at intervals include adjacent first solar cells 6 and second solar cells 7; the conductive connector 5 includes a first connecting segment 50 located on a first surface of the first solar cell 6, a second connecting segment 51 located on a second surface of the second solar cell 7, and a third connecting segment 52 connecting the first connecting segment 50 and the second connecting segment 51; the first connecting segment 50 has a first end segment 53 and a second end segment 54, the first end segment 53 is welded to the first end pad of the first solar cell 6, and the second end segment 54 is welded to the second end pad of the first solar cell 6; the second connecting segment 51 includes a third end segment 55 and a fourth end segment 56, the third end segment 55 is welded to the third end pad of the second solar cell 7, and the fourth end segment 56 is welded to the fourth end pad of the second solar cell 7; the second end segment 54 and the third end segment 55 are connected through the third connecting segment 52.

[0168] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0169] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A solar cell, characterized by, The semiconductor substrate comprises opposite first and second faces; the first face is a back light face of a solar cell, and the second face is a light receiving face of the solar cell; In a first direction, the semiconductor substrate comprises opposite first and second edges; A first passivation contact structure is formed on the first face of the semiconductor substrate; The first passivation contact structure comprises a doped conductive semiconductor layer and a tunneling layer; A first current collecting electrode is formed above the first passivation contact structure; A plurality of the first current collecting electrodes extend in a second direction and are spaced apart in the first direction; A first busbar electrode is formed above the first passivation contact structure; the first busbar electrode intersects with the plurality of the first current collecting electrodes; At least part of the first busbar electrode comprises a first end pad near the first edge and a first end busbar electrode connected to the first end pad, the first end busbar electrode being located between the first end pad and the first edge; The first end busbar electrode comprises at least two first sub-busbar electrodes; a region between the two outermost first sub-busbar electrodes constitutes a first end busbar electrode region; The first passivation contact structure has a first hollow region and a second hollow region; the first hollow region is located within the first end busbar electrode region, and the first end busbar electrode region has a plurality of the first hollow regions spaced apart in the first direction, the first hollow regions being located between two adjacent first current collecting electrodes; the second hollow region is located outside the first end busbar electrode region and between the first current collecting electrodes; The first hollow region has a first center line extending in the second direction; the second hollow region adjacent to the first hollow region in the second direction has a second center line extending in the second direction; The first center line and the second center line are collinear; or, in the first direction, the ratio of the distance between the first center line and the second center line to the width of the first hollow region in the first direction or to the width of the second hollow region in the first direction is less than or equal to 10%. At least part of the first busbar electrode further comprises a first busbar electrode connecting line, a plurality of the first busbar electrode connecting lines extend in the first direction and are spaced apart in the second direction; the first end pad is arranged at one end of the first busbar electrode connecting line near the first edge.

2. The solar cell according to claim 1, characterized in that, The widths of the first hollow region and the second hollow region in the first direction are equal.

3. The solar cell of claim 1, wherein Two adjacent first hollow regions are arranged staggered in the first direction.

4. The solar cell of claim 1, wherein The distance between two second hollow regions located on both sides of the first end pad in the second direction is L1, and the distance between two second hollow regions located on both sides of the first busbar electrode connecting line in the second direction is L2, satisfying L1>L2.

5. The solar cell of claim 2, wherein In the second direction, the distances between the two second hollow regions located on both sides of the first busbar electrode connecting line and the first busbar electrode connecting line are not equal.

6. The solar cell of claim 2, wherein, ​ 7. The solar cell of claim 1, wherein In the second direction, the distance between the first hollow region and the adjacent second hollow region is L5, and the distance between two adjacent first hollow regions in the first direction is L6, satisfying L5>L6.

8. The solar cell according to claim 1 or 7, characterized in that, In the second direction, the distance between the first hollow region and the adjacent second hollow region is L5, satisfying 50μm≤L5≤1.5mm; The distance between two adjacent first hollow regions in the first direction is L6, satisfying 50μm≤L6≤1mm.

9. The solar cell of claim 1, wherein, The portion of the first current collecting electrode adjacent to the first edge is disconnected at the first end bus electrode region, and the first passivation contact structure corresponding to the first current collecting electrode extends through the first end bus electrode region along the extension direction of the first current collecting electrode.

10. The solar cell of claim 1, wherein, The size of the first hollow region closest to the first end pad is smaller than the size of the first hollow region away from the first end pad.

11. The solar cell of claim 10, wherein, The first hollow region closest to the first end pad is closer to the first current collecting electrode located in the first end bus electrode region than the first end pad.

12. The solar cell of claim 2, wherein, The solar cell further comprises: The connection pads are arranged on the first bus electrode connection line in the first direction; The length of the second hollow region located in the circumferential direction of the connection pad in the second direction is smaller than the length of the second hollow region away from the connection pad in the second direction.

13. The solar cell of claim 1, wherein, The distance between the first hollow region and the first sub-bus electrode is greater than the distance between the first hollow region and the first current collecting electrode.

14. The solar cell according to claim 1 or 13, characterized in that, The distance between the first hollow region and the first sub-bus electrode is greater than or equal to 50μm and less than or equal to 1.5mm; The distance between the first hollow region and the first current collecting electrode is greater than or equal to 50μm and less than or equal to 1mm.

15. The solar cell of claim 1, wherein, For the same first end bus electrode, in the direction close to the first end pad, the distance between the two outermost first sub-bus electrodes decreases, and the length of the first hollow region between the two adjacent first sub-bus electrodes decreases, and the length direction of the first hollow region is consistent with the second direction.

16. The solar cell of claim 1, wherein, For the same first end bus electrode, any two adjacent first sub-bus electrodes are parallel to each other; in the first direction, the length of the first hollow region between the two adjacent first sub-bus electrodes is constant, and the length direction of the first hollow region is consistent with the second direction.

17. The solar cell of claim 1, wherein, The second hollow region comprises a plurality of second sub-hollow regions; In the second direction, a plurality of second sub-hollow regions are spaced apart; and / or, in the second direction, a plurality of second sub-hollow regions are in abutment.

18. The solar cell of claim 2, wherein, The first surface of the semiconductor substrate comprises a first region and a second region surrounding the first region; The first bus electrode and the first current collecting electrode are located in the first region; The first passivation contact structure is located in both the first region and the second region; The first passivation contact structure is located in both the first region and the second region; The first passivation contact structure further has a third hollow region, which is located in the second region and close to the first edge.

19. The solar cell of claim 1, wherein, The first end bus electrode includes three first sub-bus electrodes extending along the first direction and spaced along the second direction; The region between two adjacent first sub-bus electrodes constitutes a first sub-end bus electrode region; each first sub-end bus electrode region has the first hollow region.

20. The solar cell of claim 1, wherein, The solar cell further includes: A second passivation contact structure formed on the second surface of the semiconductor substrate; A second bus electrode formed above the second passivation contact structure; a plurality of second bus electrodes extend along the first direction and are spaced along the second direction; The second bus electrode includes a second bus electrode connecting line, a third end pad disposed in the second bus electrode connecting line close to the first edge along the first direction, and a third end bus electrode connected to the third end pad; The third end bus electrode includes at least two third sub-bus electrodes extending along the first direction and spaced along the second direction; the region between the two outermost third sub-bus electrodes constitutes a third end bus electrode region; A second current collecting electrode formed above the second passivation contact structure; a plurality of second current collecting electrodes extend along the second direction and are spaced along the first direction; the second bus electrode intersects with the plurality of second current collecting electrodes; The second passivation contact structure has a fourth hollow region and a fifth hollow region; the fourth hollow region is located in the third end bus electrode region; the fifth hollow region is located outside the third end bus electrode region and between the second current collecting electrodes.

21. A photovoltaic module, characterized by, It includes a cell string and a packaging layer; The cell string includes a plurality of conductive connectors and a plurality of solar cells according to any one of claims 1 to 20; the conductive connectors connect the plurality of solar cells in series; The packaging layer is used to cover the surface of the cell string. The solar cell includes: A semiconductor substrate having a first surface and a second surface opposite to the first surface; A first passivation contact structure formed on the first surface of the semiconductor substrate; A first bus electrode formed above the first passivation contact structure; a plurality of first bus electrodes extend along the second direction and are spaced along the first direction; The first bus electrode includes a first bus electrode connecting line, a first end pad disposed in the first bus electrode connecting line close to the first edge along the second direction, and a first end bus electrode connected to the first end pad; The first end bus electrode includes at least two first sub-bus electrodes extending along the first direction and spaced along the second direction; the region between the two outermost first sub-bus electrodes constitutes a first end bus electrode region; A first current collecting electrode formed above the first passivation contact structure; a plurality of first current collecting electrodes extend along the first direction and are spaced along the second direction; the first bus electrode intersects with the plurality of first current collecting electrodes; The first passivation contact structure has a first hollow region and a second hollow region; the first hollow region is located in the first end bus electrode region; the second hollow region is located outside the first end bus electrode region and between the first current collecting electrodes. It includes a cell string and a packaging layer; The cell string includes a plurality of conductive connectors and a plurality of solar cells according to any one of claims 1 to 20; the conductive connectors connect the plurality of solar cells in series; The packaging layer is used to cover the surface of the cell string.

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