Back contact solar cell with no busbars

Abstract

The present disclosure relates to the technical field of solar cells, and discloses a main grid-free back contact solar cell. The cell comprises a base layer, a first doped structure, a second doped structure, a first grid line, a second grid line, a first auxiliary doped structure and / or a second auxiliary doped structure. The auxiliary doped structure is arranged in the broken area of the doped structure, and the auxiliary doped structure and the pad point with the same polarity as the auxiliary doped structure are further limited to have different widths, which helps to expand the carrier collection area of the broken area, realize independent function implementation of the pad point and the auxiliary doped structure, and on-demand optimization of the functions. When the width of the auxiliary doped structure is greater than the width of the pad point, it helps to enhance the current plane transmission capacity, improve the redundancy and process tolerance of the virtual connection resistance; when the width of the pad point is greater than the width of the auxiliary doped structure, it helps to lengthen the length of the doped structure and the grid line with different polarities on both sides of the broken area and the auxiliary doped structure, and the carrier collection area becomes larger.

Description

Technical Field

[0001] This disclosure relates to the field of solar cell technology, specifically to a gridless back-contact solar cell. Background Technology

[0002] Back-contact solar cells, with all electrodes located on the back of the cell, effectively improve solar energy utilization and cell conversion efficiency, making them a key development direction for high-efficiency photovoltaic cells. In back-contact solar cells, n-type and p-type doped regions are typically arranged alternately in an interdigitated pattern on the back of the cell. Each doped region has a corresponding polarity sub-grid line to achieve effective separation and collection of photogenerated carriers. As a core cost-reduction technology for back-contact solar cells, gridless patterning technology is being gradually promoted. In gridless back-contact solar cells, several pads are usually set on the sub-grid lines so that the pads can be directly connected via solder ribbons to achieve reliable current collection and extraction.

[0003] However, current gridless patterned solutions still face the following technical challenges in practical applications: First, to ensure that grid lines of different polarities do not short-circuit when connecting solder strips, insulating adhesive is typically placed at the boundary between the n-type and p-type doped regions. Due to the thickness of the insulating adhesive, the solder strip often needs to cross the adhesive or areas of significant height change when overlapping with the pads, resulting in an undulating welding state. This makes it impossible for the solder strip to reliably overlap all the pre-set pads, leading to incomplete connections or detachment between some pads and the solder strip, causing current transmission obstacles and affecting module reliability and output power. Based on this, some solutions attempt to remove grid lines of opposite polarity at the pad locations to avoid direct contact between the solder strip and the insulating adhesive, thereby reducing the risk of poor solder strip overlap. However, this results in a lack of carrier collection capacity for the opposite polarity grid lines in that area, preventing the effective extraction of locally generated photocarriers and reducing the overall carrier collection efficiency and photoelectric conversion efficiency of the cell. Summary of the Invention

[0004] This disclosure provides a gridless back-contact solar cell to solve the problem that existing gridless back-contact solar cells cannot simultaneously achieve reliable current output and efficient photogenerated carrier collection.

[0005] In a first aspect, this disclosure provides a gridless back-contact solar cell, comprising: a substrate layer, a first doped structure, a second doped structure, a first grid line, a second grid line, a first auxiliary doped structure, and / or a second auxiliary doped structure. The substrate layer includes a light-receiving surface and a back-lighting surface opposite to each other; the first doped structure and the second doped structure extend along a first direction and are alternately formed along a second direction on the back-lighting surface, the doping types of the first and second doped structures are opposite, the first direction and the second direction form a predetermined angle, the first doped structure has a first interruption region in the first direction, the second doped structure has a second interruption region in the first direction, and the first and second interruption regions are staggered in the first direction; a first grid line is correspondingly disposed on the first doped structure, and a second grid line is correspondingly disposed on the second doped structure; the first grid line also has a first bonding pad, and the second grid line also has a second bonding pad; multiple first bonding pads are provided. The pads are collinearly arranged along a second direction and adapted to correspond to a second interruption region; multiple second pads are collinearly arranged along a second direction and adapted to correspond to a first interruption region; both a first auxiliary doping structure and a second auxiliary doping structure extend along a second direction; the first auxiliary doping structure is adapted to be formed within the second interruption region and connects multiple first doping structures; the second auxiliary doping structure is adapted to be formed within the first interruption region and connects multiple second doping structures; the width of the first pad in the first direction is not equal to the width of the first auxiliary doping structure in the first direction, and / or the width of the second pad in the first direction is not equal to the width of the second auxiliary doping structure in the first direction.

[0006] Beneficial effects: This disclosure provides an auxiliary doped structure extending along a second direction within the interrupted region of the doped structure, and further defines that the auxiliary doped structure and its corresponding pad with the same polarity have different widths. First, the auxiliary doping structure expands the carrier collection area at the break point, which helps improve the photogenerated carrier collection efficiency in this region and the overall battery. Second, setting different widths for the auxiliary doping structure and the pads with the same polarity breaks the one-to-one width constraint of conventional solutions. This helps to achieve independent functionality of the pads and auxiliary doping structures and optimize functions as needed. Specifically, on the one hand, when the width of the auxiliary doping structure is greater than the width of the pads, it helps to enhance the current plane transmission capability, improve the resistance to virtual connection redundancy and process tolerance, and improve the reliability and manufacturing yield of the module. That is, even if the welding reliability is poor, there are still enough carriers to be collected and output. On the other hand, when the width of the pads is greater than the width of the auxiliary doping structure, that is, the width of the auxiliary doping structure can be narrowed, it helps to extend the length of the doped structures with different polarities from the auxiliary doping structure on both sides of the break region and the grid lines on the doped structures. This makes the carrier collection area larger, reduces recombination losses, and improves the battery conversion efficiency.

[0007] In one alternative implementation, the width of the first pad in the first direction is greater than the width of the first auxiliary doped structure in the first direction; and / or, the width of the second pad in the first direction is greater than the width of the second auxiliary doped structure in the first direction.

[0008] Beneficial effects: This setting further narrows the width of the auxiliary doped structure, which helps to extend the length of the doped structures with different polarities from the auxiliary doped structure on both sides of the interruption region and the gate lines on the doped structure, thus making the carrier collection region larger.

[0009] In one optional embodiment, the system further includes: a first auxiliary gate line and / or a second auxiliary gate line, both extending along a second direction; the first auxiliary gate line is adapted to be disposed on a first auxiliary doped structure and to connect at least a portion of the first pad; the second auxiliary gate line is adapted to be formed on a second auxiliary doped structure and to connect at least a portion of the second pad.

[0010] Beneficial effects: Even if the solder ribbon is laid on each pad point along the second direction and some pad points cannot be effectively overlapped by the solder ribbon due to the undulation, the current of these unoverlapped pad points can still be diverted to the pad points at the overlap by the auxiliary grid line, ensuring reliable output of charge carriers and the overall photoelectric conversion efficiency of the battery.

[0011] In one alternative implementation, the first auxiliary gate line connects all first pads arranged along the second direction; and / or, the second auxiliary gate line connects all second pads arranged along the second direction.

[0012] Beneficial effects: The interconnected first and second auxiliary grid lines and the corresponding first and second auxiliary doped structures ensure, on the one hand, that the disconnection points have carrier collection capabilities with opposite polarities, ensuring that photogenerated carriers in this region and the entire battery can be effectively extracted and utilized; on the other hand, even if the solder ribbon is laid on each pad point along the second direction and some pad points cannot be effectively overlapped by the solder ribbon due to the undulations, the current of these unoverlapped pad points can still be guided by the auxiliary grid lines to the pad points at the overlap points, ensuring reliable output of carriers and the overall photoelectric conversion efficiency of the battery.

[0013] In one alternative implementation, in the first direction, the centerline of the first auxiliary gate line is configured to coincide with the centerline of the first auxiliary doped structure, or to be offset relative to the centerline of the first auxiliary doped structure; and / or, the centerline of the second auxiliary gate line is configured to coincide with the centerline of the second auxiliary doped structure, or to be offset relative to the centerline of the second auxiliary doped structure.

[0014] In one optional embodiment, the width of the first gate line and the second gate line in the second direction ranges from 5 to 30 μm, and the width of the first auxiliary gate line and the second auxiliary gate line in the first direction ranges from 10 to 50 μm.

[0015] Beneficial effects: The auxiliary grid lines are different from the main grid lines that are conventionally laid along the second direction. Their width is smaller than that of the conventional main grid lines, which helps to reduce costs. The width of the auxiliary grid lines can be equal to or similar to the width of the sub-grid lines, that is, the first grid line and the second grid line. For example, they can be equal to the width of the sub-grid lines, which facilitates the integral molding of the grid lines during printing and simplifies the process preparation.

[0016] In one alternative implementation, it further includes: A first insulating layer is adapted to be disposed on a first doped structure; the first insulating layer is located at least at the end of the first doped structure near the first break region to cover the corresponding first doped structure and the first gate line, and at least exposes the first pad point; A second insulating layer is adapted to be disposed on the second doped structure; the second insulating layer is located at least at the end of the second doped structure near the second break region to cover the corresponding second doped structure and the second gate line, and at least exposes the second pad point.

[0017] Beneficial effects: After the fabrication of complete unit cells, including the first doped structure, second doped structure, first auxiliary doped structure, second auxiliary doped structure, first grid line, second grid line, first auxiliary grid line, and second auxiliary grid line, multiple cells are connected by solder ribbons. Insulating layers are placed in areas where welding is unnecessary and short circuits are likely to occur to provide electrical isolation, ensuring efficient extraction of photogenerated carriers and improving the overall photoelectric conversion efficiency of the battery. A first insulating layer is placed at the end of the first doped structure near the first break region to prevent incorrect connection between the solder ribbon and the second auxiliary grid line / second pad when the ribbon is laid on the second auxiliary doped structure, thus avoiding short circuits between the different polarity structures. Similarly, a second insulating layer is placed at the end of the second doped structure near the second break region to prevent incorrect connection between the solder ribbon and the second doped structure and second grid line / second pad when the ribbon is laid on the first auxiliary doped structure, thus avoiding short circuits between the different polarity structures.

[0018] In one alternative embodiment, the surface of the second doped structure is relatively higher than the surface of the first doped structure in the thickness direction of the substrate layer.

[0019] Beneficial effects: In the gridless back-contact solar cell disclosed herein, the two different doping types of doping structures have a high relative difference. This structure can be determined by the order of preparation of different doping structures. For example, if the first doping structure is prepared first and the second doping structure is prepared later, the height of the first doping structure is often higher than that of the second doping structure. Such a structure with a high difference helps to carry out differentiated design for different doping structures in the future, improving the flexibility of cell design. At the same time, such a structure with different heights makes the cell surface have an uneven structure, which improves the light trapping performance to a certain extent.

[0020] In one alternative embodiment, the surface of the substrate layer corresponding to the second doped structure is higher than the surface of the substrate layer corresponding to the first doped structure.

[0021] Beneficial effects: Specifically, the surface of the first doped structure being relatively higher than the surface of the second doped structure can be such that the surface of the substrate layer corresponding to the second doped structure is higher than the surface of the substrate layer corresponding to the first doped structure. In this disclosure, the height of the second region is greater than the height of the first region, and the height of the first region is greater than the height of the isolation region. This directly presents an uneven morphology on the surface of the substrate layer, further optimizing light-trapping performance, ensuring optimized subsequent film deposition quality, and simultaneously helping to reduce parasitic absorption at the interface.

[0022] In one alternative implementation, only the second doped structure forms the second break region, the second break region is correspondingly disposed with the first pad point in the first direction, the plurality of first doped structures are connected by a first auxiliary doped structure formed in the second break region, and the plurality of first pad points are adapted to be connected by a first auxiliary gate line. The first insulating layer is configured to at least cover a portion of the first doped structure corresponding to the second pad and to at least expose the first pad; in the thickness direction of the substrate layer, the surface of the second pad is relatively higher than the surface of the first insulating layer.

[0023] Beneficial effects: Given that the second doped structure is relatively higher than the first doped structure, a second interruption region can be formed only in the second doped structure, while the first doped structure does not have a first interruption region. This is because when the solder ribbon is placed on the relatively protruding second doped structure to connect with the second gate line and the second pad, even if a first insulating layer is placed on the first doped structure, it will not be higher than the original second doped structure, thus not affecting the reliable connection between the solder ribbon and the second gate line and the second pad. Therefore, it can be designed that the first doped structure has a first insulating layer to avoid contact with the solder ribbon, achieving carrier extraction from the second doped structure; while the second doped structure has a second interruption region, and a first auxiliary doped structure and a first auxiliary gate line are placed in the second interruption region to facilitate the connection between the solder ribbon and the first gate line and the first pad, achieving carrier extraction from the first doped structure.

[0024] In one alternative embodiment, a solder layer is also adapted to be disposed on the first solder pad and / or the second solder pad.

[0025] Beneficial effects: The solder layer can be solder paste or other solder materials, which helps to further enhance the reliability of the connection between the solder strip and the pad. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the specific embodiments of this disclosure or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of a gridless back-contact solar cell according to an embodiment of the present disclosure; Figure 2 This is a top view schematic diagram of a gridless back-contact solar cell according to an embodiment of the present disclosure; Figure 3 This is a partial top view of a gridless back-contact solar cell according to an embodiment of the present disclosure; Figure 4 This is another partial top view of a gridless back-contact solar cell according to an embodiment of the present disclosure; Figure 5 This is another top view schematic diagram of a gridless back-contact solar cell according to an embodiment of the present disclosure.

[0028] Explanation of reference numerals in the attached figures: 1. Substrate layer; 101. Light-receiving surface; 102. Backlight-receiving surface; A. First region; B. Second region; C. Isolation region; 2. First doped structure; 201. First interruption region; 3. Second doped structure; 301. Second interruption region; 4. First gate line; 5. Second gate line; 6. First auxiliary doped structure; 7. Second auxiliary doped structure; 8. First auxiliary gate line; 9. Second auxiliary gate line; 10. First pad; 11. Second pad; 12. First insulating layer; 13. Second insulating layer; 14. Passivation antireflection layer. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0030] In related gridless patterning schemes, to ensure that grid lines of different polarities do not short-circuit when connecting solder pads, insulating adhesive is usually placed at the boundary between the n-type and p-type doped regions. However, placing insulating adhesive can easily lead to poor soldering, affecting current output; while removing the insulating adhesive and the grid lines of opposite polarity at the solder pad location will result in insufficient carrier collection in that area, and local photogenerated carriers cannot be effectively discharged, reducing the overall photoelectric conversion efficiency of the battery. To balance carrier collection capability and solder pad overlap reliability, related schemes usually set an auxiliary doped structure extending along the second direction in the interrupted region to connect doped structures of the same polarity to achieve current transmission. However, the setting of the auxiliary doped structure in this scheme changes the effective collection area of ​​doped structures of different polarities, thus limiting the effective collection of photogenerated carriers and restricting further improvement of the battery's photoelectric conversion efficiency. Therefore, how to further improve the photogenerated carrier collection efficiency in each region on the back of the battery, and improve the overall photoelectric conversion efficiency of the battery, while ensuring reliable overlap between the solder pad and the solder pad to ensure current output, is one of the problems that urgently need to be solved in this field.

[0031] Based on this, refer to Figures 1 to 5This disclosure provides a gridless back-contact solar cell, comprising: a substrate layer 1, a first doped structure 2, a second doped structure 3, a first grid line 4, a second grid line 5, a first auxiliary doped structure 6, and a second auxiliary doped structure 7. The substrate layer 1 includes a light-receiving surface 101 and a back-lighting surface 102 facing each other; the first doped structure 2 and the second doped structure 3 extend along a first direction and are alternately formed on the back-lighting surface 102 along a second direction, with opposite doping types. The first direction and the second direction form a predetermined angle. The first doped structure 2 has a first interruption region 201 in the first direction, and the second doped structure 3 has a second interruption region 301 in the first direction. The first interruption region 201 and the second interruption region 301 are staggered in the first direction. The first grid line 4 is correspondingly disposed on the first doped structure 2, and the second grid line 5 is correspondingly disposed on the second doped structure 3. The first grid line 4 also has a first pad 10, and the second grid line 5 also has a second pad 10. 1. A plurality of first pads 10 are collinearly arranged along a second direction and adapted to correspond to a second interruption region 301; a plurality of second pads 11 are collinearly arranged along a second direction and adapted to correspond to a first interruption region 201; a first auxiliary doping structure 6 and a second auxiliary doping structure 7 both extend along a second direction; the first auxiliary doping structure 6 is adapted to be formed within the second interruption region 301 and connects to a plurality of first doping structures 2; the second auxiliary doping structure 7 is adapted to be formed within the first interruption region 201 and connects to a plurality of second doping structures 3; the width of the first pads 10 in the first direction is not equal to the width of the first auxiliary doping structure 6 in the first direction; the width of the second pads 11 in the first direction is not equal to the width of the second auxiliary doping structure 7 in the first direction.

[0032] The aforementioned substrate 1 can be a silicon substrate. A first doped structure 2 and a second doped structure 3, arranged in an interdigitated pattern, are formed on the back surface 102 of the substrate 1. One of the first doped structure 2 and the second doped structure 3 is p-type doped, and the other is n-type doped. Figures 2 to 5 As shown, both the first doped structure 2 and the second doped structure 3 extend along a first direction and are arranged alternately along a second direction, with the first direction perpendicular to the second direction. Based on this, a first grid line 4 is provided on the first doped structure 2, and a second grid line 5 is provided on the second doped structure 3. Both the first grid line 4 and the second grid line 5 are highly corrosive sub-grid lines, meeting the requirements of a gridless cell. A widened and thickened first solder pad 10 is also provided on the first grid line 4. The first solder pad 10 increases the contact area between the solder strip and the first grid line 4 when they are connected, ensuring a reliable connection. Similarly, a widened and thickened second solder pad 11 is provided on the second grid line 5. The second solder pad 11 increases the contact area between the solder strip and the second grid line 5 when they are connected, ensuring a reliable connection.

[0033] Based on the above solutions, such as Figure 2 As shown, in one embodiment, at least a portion of the first doped structure 2 has a first interruption region 201 in its extension direction, i.e., the first direction. Multiple first interruption regions 201 are collinearly arranged along the second direction. The straight line containing multiple second pads 11 in the second direction corresponds to the straight line containing multiple first interruption regions 201, i.e., they coincide or have a slight displacement in the first direction, ensuring that when the solder strip is connected to the second pad 11, the sides do not exceed the area containing the first interruption region 201 in the first direction. Similarly, at least a portion of the second doped structure 3 has a first interruption region 201 in its extension direction, i.e., the first direction. The second interruption region 301 is provided. Multiple second interruption regions 301 are arranged collinearly along the second direction. The straight lines of multiple first pad points 10 in the second direction correspond to the straight lines of multiple second interruption regions 301, that is, they coincide or have a slight displacement in the first direction, to ensure that when the solder strip is connected to the first pad point 10, the two sides in the first direction will not exceed the area of ​​the second interruption region 301. The straight lines of multiple first interruption regions 201 and multiple second interruption regions 301 are staggered in the first direction, that is, there is a certain gap between them, which facilitates the connection of solder strips of different polarities. At the same time, a second auxiliary doping structure 7 extending along the second direction is provided in the first interruption region 201 to connect multiple second doping structures 3 to form an overall structure of the second doping type. Similarly, a first auxiliary doping structure 6 extending along the second direction is provided in the second interruption region 301 to connect multiple first doping structures 2 to form an overall structure of the first doping type. Based on this, the width of the first pad 10 in the first direction is not equal to the width of the first auxiliary doped structure 6 in the first direction. Similarly, the width of the second pad 11 in the first direction can be set to be not equal to the width of the second auxiliary doped structure 7 in the first direction. Here, the widths can be greater than or less than each other.

[0034] This auxiliary doping structure, extending along the second direction within the interrupted region, further defines different widths for the auxiliary doping structure and its corresponding pad with the same polarity. Firstly, the auxiliary doping structure expands the carrier collection area at the interruption point, helping to improve the photogenerated carrier collection efficiency in this region and the overall battery. Secondly, setting different widths for the auxiliary doping structure and the pad with the same polarity breaks the conventional one-to-one width constraint, facilitating independent functional implementation of the pad and auxiliary doping structure, as well as on-demand functional optimization. Specifically, on the one hand, such as... Figure 3 As shown, when the width of the auxiliary doped structure is greater than the width of the solder pad, it helps to enhance the current plane transport capability, improve the resistance to virtual connections and redundancy, and increase process tolerance, thereby improving component reliability and manufacturing yield. That is, even if the soldering reliability is poor, there are still enough charge carriers to be collected and output. On the other hand, as Figure 4 As shown, when the width of the pad is greater than the width of the auxiliary doped structure, that is, the width of the auxiliary doped structure can be narrowed, it helps to extend the length of the doped structures with different polarities from the auxiliary doped structure on both sides of the interruption region and the gate line on the doped structure, thereby making the carrier collection area larger, reducing recombination loss and improving the battery conversion efficiency.

[0035] like Figure 5 As shown, in another embodiment, only one of the first interruption region 201 and the second interruption region 301 may be provided, and correspondingly, only one of the first auxiliary doping structure 6 and the second auxiliary doping structure 7 may be provided. Exemplarily, the other part without interruption regions can achieve reliable electrical connection with the solder strip by means of providing an insulating layer or the like.

[0036] In some embodiments, such as Figure 3 As shown, to facilitate the formation of the solder pads and ensure the number of charge carriers in the opposite polarity doped structures within the interrupted region, the width of the first auxiliary doped structure 6 in the first direction is greater than the width of the first solder pad 10 in the first direction. Similarly, the width of the second auxiliary doped structure 7 in the first direction is greater than the width of the second solder pad 11 in the first direction. Of course, this arrangement is based on the presence of the first auxiliary doped structure 6 and the second auxiliary doped structure 7. When the first auxiliary doped structure 6 or the second auxiliary doped structure 7 is not present, the above arrangement is naturally not applicable, and the same applies below.

[0037] Similarly, provided that the first auxiliary doping structure 6 and / or the second auxiliary doping structure 7 are present, in other embodiments, such as Figure 2 , Figure 4 and 5 As shown, the width L1 of the first pad 10 in the first direction is greater than the width L2 of the first auxiliary doped structure 6 in the first direction; the width of the second pad 11 in the first direction is greater than the width of the second auxiliary doped structure 7 in the first direction. This further narrows the width of the auxiliary doped structure, which helps to extend the length of the doped structures with different polarities from the auxiliary doped structure on both sides of the interruption region and the gate lines on the doped structure, thus making the carrier collection region larger.

[0038] In some embodiments, such as Figure 2 As shown, the above-mentioned gridless back contact solar cell further includes: a first auxiliary grid line 8 and a second auxiliary grid line 9, both of which extend along a second direction. The first auxiliary grid line 8 is adapted to be disposed on the first auxiliary doped structure 6 and connects to at least a portion of the first pad 10. The second auxiliary grid line 9 is adapted to be formed on the second auxiliary doped structure 7 and connects to at least a portion of the second pad 11.

[0039] Even if the solder ribbon is laid on each pad along the second direction and some pads cannot be effectively overlapped due to the undulations, the current of these unoverlapped pads can still be diverted to the pads at the overlap by the auxiliary grid line, ensuring reliable output of charge carriers and the overall photoelectric conversion efficiency of the battery.

[0040] Of course, the first auxiliary gate line 8 and the second auxiliary gate line 9 can be set separately. For example, only the first auxiliary gate line 8 or only the second auxiliary gate line 9 can be set. The auxiliary gate lines and the auxiliary doped structures do not have a corresponding relationship. That is, the region with the auxiliary doped structure does not necessarily have an auxiliary gate line.

[0041] Furthermore, such as Figure 2 As shown, in some embodiments, the first auxiliary doped structure 6 connects to all the first doped structures 2 arranged along the second direction, and correspondingly, the first auxiliary gate line 8 connects to all the first pads 10 arranged along the second direction; the second auxiliary doped structure 7 connects to all the second doped structures 3 arranged along the second direction, and correspondingly, the second auxiliary gate line 9 connects to all the second pads 11 arranged along the second direction.

[0042] That is, the first auxiliary doped structure 6 and the second auxiliary doped structure 7 are both arranged to penetrate the entire substrate layer 1 along the second direction. The first auxiliary doped structure 6 is connected to all the first doped structures 2 arranged along the second direction, and the second auxiliary doped structure 7 is connected to all the second doped structures 3 arranged along the second direction. The first auxiliary gate line 8 and the second auxiliary gate line 9 are both arranged to penetrate the entire substrate layer 1 along the second direction. The first auxiliary gate line 8 is connected to all the first gate lines 4 arranged along the second direction, and the second auxiliary gate line 9 is connected to all the second gate lines 5 arranged along the second direction.

[0043] The interconnected first auxiliary grid line 8 and second auxiliary grid line 9, along with the corresponding first auxiliary doped structure 6 and second auxiliary doped structure 7, ensure, on the one hand, that carriers with opposite polarities can be collected at the break points, ensuring that photogenerated carriers in this region and the entire battery can be effectively extracted and utilized; on the other hand, even if the solder ribbon is laid along the second direction on each pad point and some pad points cannot be effectively overlapped by the solder ribbon due to the undulations, the current of these unoverlapped pad points can still be guided by the auxiliary grid line to the pad points at the overlap points, ensuring reliable output of carriers and the overall photoelectric conversion efficiency of the battery.

[0044] Of course, in other embodiments, some auxiliary grid lines can be set through the entire structure, while other auxiliary grid lines can be set locally in the second direction according to specific requirements, such as only in the edge area or other locations where cold solder joints are likely to occur.

[0045] In some embodiments, in a first direction, the centerline of the first auxiliary gate line 8 is configured to coincide with the centerline of the first auxiliary doped structure 6, or to be offset relative to the centerline of the first auxiliary doped structure 6; and / or, the centerline of the second auxiliary gate line 9 is configured to coincide with the centerline of the second auxiliary doped structure 7, or to be offset relative to the centerline of the second auxiliary doped structure 7.

[0046] In other words, the auxiliary gate line does not necessarily have to be located at the center of both the auxiliary doped structure and the pad simultaneously with the solder ribbon. When the solder ribbon is placed on the auxiliary doped structure, its centerline can be located on the centerline of the auxiliary doped structure or it can be offset to some extent. Similarly, the auxiliary gate line can correspond to the centerline of the auxiliary doped structure or be offset relative to it. The offset can be set within the width range of the pad in the first direction, as long as a good connection between the auxiliary gate line and the pad is achieved. That is, the auxiliary gate line does not necessarily have to be located in the middle of the solder ribbon. Since the width of the solder ribbon is much larger than the width of the auxiliary gate line, when the solder ribbon is placed on the auxiliary doped structure, as long as the auxiliary gate line and the pad are reliably connected, even if the auxiliary gate line has a certain offset, it will not affect the carrier output performance of the area where the auxiliary gate line is located. More importantly, the offset auxiliary gate line can also avoid further thickening the height of the pad, which helps the solder ribbon overlap to each pad.

[0047] It is known that the width of the main gate line in conventional schemes is usually above 100 μm. However, in this disclosure, the width of the first gate line 4 and the second gate line 5 in the second direction ranges from 5 to 30 μm, and the width of the first auxiliary gate line 8 and the second auxiliary gate line 9 in the first direction ranges from 10 to 50 μm. That is, the auxiliary gate lines are different from the main gate lines conventionally laid along the second direction; their width is smaller than that of conventional main gate lines, which helps to reduce costs. Moreover, the width of the auxiliary gate lines can be equal to or equivalent to the width of the sub-gate lines, i.e., the width of the first gate line 4 and the second gate line 5. For example, it can be equal to the width of the sub-gate lines, which facilitates integral molding during gate line printing and simplifies the manufacturing process.

[0048] In some embodiments, such as Figure 2 As shown, the aforementioned gridless back-contact solar cell further includes: a first insulating layer 12 and a second insulating layer 13. The first insulating layer 12 is adapted to be disposed on the first doped structure 2. The first insulating layer 12 is located at least at the end of the first doped structure 2 near the first interruption region 201 to cover the corresponding first doped structure 2 and the first grid line 4, and exposes at least the first pad 10. The second insulating layer 13 is adapted to be disposed on the second doped structure 3. The second insulating layer 13 is located at least at the end of the second doped structure 3 near the second interruption region 301 to cover the corresponding second doped structure 3 and the second grid line 5, and exposes at least the second pad 11.

[0049] Specifically, after the first doped structure 2, the second doped structure 3, the first auxiliary doped structure 6, the second auxiliary doped structure 7, the first grid line 4, the second grid line 5, the first auxiliary grid line 8, and the second auxiliary grid line 9 are fabricated to obtain a complete unit cell, before connecting multiple cells with solder ribbons, an insulating layer is set in the area where welding is not required and welding short circuits are prone to occur for electrical isolation, to ensure the efficient export of photogenerated carriers and improve the overall photoelectric conversion efficiency of the cell. For example, a first insulating layer 12 is provided at the end of the first doped structure 2 near the first break region 201 to prevent the solder ribbon from being mistakenly connected to the first doped structure 2 and the first gate line 4 on both sides of the first break region 201 when it is laid on the second auxiliary doped structure 7 and connected to the second auxiliary gate line 9 and the second pad 11, thereby causing a short circuit in the connection between structures of different polarities. Similarly, a second insulating layer 13 is provided at the end of the second doped structure 3 near the second break region 301 to prevent the solder ribbon from being mistakenly connected to the second doped structure 3 and the second gate line 5 on both sides of the second break region 301 when it is laid on the first auxiliary doped structure 6 and connected to the first auxiliary gate line 8 and the first pad 10, thereby causing a short circuit in the connection between structures of different polarities.

[0050] Of course, the first insulating layer 12 and the second insulating layer 13 can not only cover the ends of the first doped structure 2 and the second doped structure 3, as long as they can expose the gate lines and pads that need to be exposed, so as to ensure the electrical connection effect.

[0051] like Figure 1 As shown, in one embodiment, in the above-described gridless back contact solar cell, the surface of the second doped structure 3 is relatively higher than the surface of the first doped structure 2 in the thickness direction of the substrate layer 1.

[0052] The first doped structure 2 and the second doped structure 3 here are not limited to specific doping types. That is, in the gridless back contact solar cell of this disclosure, the two doped structures of different doping types have a high relative difference. This structure can be determined by the order of preparation of different doped structures. For example, if the first doped structure 2 is prepared first and the second doped structure 3 is prepared later, the height of the first doped structure 2 is often higher than the height of the second doped structure 3. Such a structure with a high difference helps to carry out differentiated design for different doped structures in the future, improves the flexibility of cell design, and at the same time, such a structure with different heights makes the cell surface present an uneven structure, which improves the light trapping performance to a certain extent.

[0053] This disclosure takes the second doped structure 3 as a p-type doped structure and the first doped structure 2 as an n-type doped structure as an example, that is, the p-type doped structure is superior to the n-type doped structure.

[0054] Specifically, the surface of the first doped structure 2 being relatively higher than the surface of the second doped structure 3 can be that the surface of the substrate layer 1 corresponding to the second doped structure 3 is higher than the surface of the substrate layer 1 corresponding to the first doped structure 2.

[0055] Taking a portion of the backlight surface 102 corresponding to the first doped structure 2 as region A, a portion of the backlight surface 102 corresponding to the second doped structure 3 as region B, and an isolation region C between region A and region B as an example, this disclosure sets the height of region B to be greater than the height of region A, and the height of region A to be greater than the height of isolation region C. This directly presents an uneven morphology on the surface of the substrate layer 1, further optimizing light-trapping performance, ensuring optimized subsequent film deposition quality, and simultaneously helping to reduce parasitic absorption at the interface.

[0056] Based on the fact that the surface of the second doped structure 3 is relatively higher than the surface of the first doped structure 2, in some embodiments, such as Figure 5 As shown, the second doped structure 3 forms a second interruption region 301, which is correspondingly disposed with the first pad 10 in the first direction. Multiple first doped structures 2 are connected by a first auxiliary doped structure 6 formed within the second interruption region 301, and multiple first pads 10 are connected by a first auxiliary gate line 8. Based on this, the first insulating layer 12 is configured to at least cover a portion of the first doped structure 2 corresponding to the second pad 11, and at least expose the first pad 10; in the thickness direction of the substrate layer 1, the surface of the second pad 11 is relatively higher than the surface of the first insulating layer 12.

[0057] That is, based on the fact that the second doped structure 3 is relatively higher than the first doped structure 2, it is possible to set only the second doped structure 3 to form the second interruption region 301, while the first doped structure 2 does not have the first interruption region 201. This is because when the solder strip is set on the relatively protruding second doped structure 3 to connect with the second gate line 5 and the second pad 11, even if the first insulating layer 12 is set on the first doped structure 2, it will not be higher than the original second doped structure 3, and will not affect the reliable connection between the solder strip and the second gate line 5 and the second pad 11. Therefore, it can be designed that the first insulating layer 12 is set on the first doped structure 2 to avoid contact with the solder strip, so as to realize the carrier output of the second doped structure 3; while the second doped structure 3 has the second interruption region 301, and the first auxiliary doped structure 6 and the first auxiliary gate line 8 are set in the second interruption region 301 to facilitate the connection between the solder strip and the first gate line 4 and the first pad 10, so as to realize the carrier output of the first doped structure 2.

[0058] Of course, if the first doped structure 2 is higher than the second doped structure 3, a second insulating layer 13 can be designed on the second doped structure 3 to avoid contact with the solder strip, thereby realizing the outflow of charge carriers from the first doped structure 2. The first doped structure 2 is provided with a first interruption region 201, and a second auxiliary doped structure 7 and a second auxiliary gate line 9 are provided in the first interruption region 201 to facilitate the connection between the solder strip and the second gate line 5 and the second solder pad 11, thereby realizing the outflow of charge carriers from the second doped structure 3.

[0059] In some embodiments, such as Figure 5 As shown, the width of the first insulating layer 12 in the first direction is greater than the width of the second pad 11 in the first direction, ensuring that when the solder ribbon is connected to the second pad 11, the first insulating layer 12 fully covers the first gate line 4 in the first direction, thereby achieving electrical isolation.

[0060] In some embodiments, in the above-described gridless back contact solar cell, a solder layer is also suitable for being provided on the first solder pad 10 and / or the second solder pad 11. The solder layer may be solder paste or other solder materials, which helps to further enhance the connection reliability between the solder strip and the solder pad.

[0061] Of course, by setting a first insulating layer 12 on the first doped structure 2 to avoid contact with the solder strip, the carriers of the second doped structure 3 are extracted. The second doped structure 3 is provided with a second interruption region 301, and in the scheme of setting a first auxiliary doped structure 6 and a first auxiliary gate line 8 in the second interruption region 301, the height difference between the first region A and the second region B on the backlight surface 102, plus the setting of the doped structure, plus the solder layer, helps to further increase the height difference.

[0062] In some embodiments, such as Figure 1 As shown, the light-receiving surface 101 of the substrate 1 is configured with a textured surface, and a passivation antireflection layer 14 is covered on it to reduce the loss of reflected light.

[0063] Further functional descriptions of the above structures are the same as those of the corresponding embodiments described above, and will not be repeated here.

[0064] Although embodiments of the present disclosure have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present disclosure, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A gridless back-contact solar cell, characterized in that, include: A substrate layer, the substrate layer comprising an opposing light-receiving surface and a backlighting surface; A first doped structure and a second doped structure are provided extending along a first direction and alternately formed along a second direction on the backlight surface. The doping types of the first doped structure and the second doped structure are opposite. The first direction and the second direction form a preset angle. The first doped structure has a first interruption region in the first direction, and / or the second doped structure has a second interruption region in the first direction. The first interruption region and the second interruption region are staggered in the first direction. A first gate line and a second gate line are respectively disposed on the first doped structure and the second gate line is respectively disposed on the second doped structure. A first pad is also disposed on the first gate line and a second pad is also disposed on the second gate line. A plurality of first pads are collinearly disposed along the second direction and adapted to correspond to the second interruption region. A plurality of second pads are collinearly disposed along the second direction and adapted to correspond to the first interruption region. The first auxiliary doping structure and / or the second auxiliary doping structure are both extended along the second direction; the first auxiliary doping structure is adapted to be formed in the second interruption region and connects to a plurality of the first doping structures; the second auxiliary doping structure is adapted to be formed in the first interruption region and connects to a plurality of the second doping structures; the width of the first pad in the first direction is not equal to the width of the first auxiliary doping structure in the first direction, and / or the width of the second pad in the first direction is not equal to the width of the second auxiliary doping structure in the first direction.

2. The gridless back-contact solar cell according to claim 1, characterized in that, The width of the first pad in the first direction is greater than the width of the first auxiliary doped structure in the first direction; And / or, the width of the second pad in the first direction is greater than the width of the second auxiliary doped structure in the first direction.

3. The gridless back-contact solar cell according to claim 1, characterized in that, Also includes: The first auxiliary gate line and / or the second auxiliary gate line are both extended along the second direction; the first auxiliary gate line is adapted to be disposed on the first auxiliary doped structure and connects to at least a portion of the first pad; the second auxiliary gate line is adapted to be formed on the second auxiliary doped structure and connects to at least a portion of the second pad.

4. The gridless back-contact solar cell according to claim 3, characterized in that, The first auxiliary gate line connects all first pads arranged along the second direction; and / or, the second auxiliary gate line connects all second pads arranged along the second direction.

5. The gridless back-contact solar cell according to claim 3, characterized in that, In the first direction, the centerline of the first auxiliary gate line is configured to coincide with the centerline of the first auxiliary doped structure, or to be offset relative to the centerline of the first auxiliary doped structure; and / or, the centerline of the second auxiliary gate line is configured to coincide with the centerline of the second auxiliary doped structure, or to be offset relative to the centerline of the second auxiliary doped structure.

6. The gridless back-contact solar cell according to claim 3, characterized in that, The width of the first gate line and the second gate line in the second direction ranges from 5 to 30 μm, and the width of the first auxiliary gate line and the second auxiliary gate line in the first direction ranges from 10 to 50 μm.

7. The gridless back-contact solar cell according to claim 1, characterized in that, Also includes: A first insulating layer is adapted to be disposed on the first doped structure; the first insulating layer is located at least at the end of the first doped structure near the first break region to cover the corresponding first doped structure and the first gate line, and at least exposes the first pad point; A second insulating layer is adapted to be disposed on the second doped structure; the second insulating layer is located at least at the end of the second doped structure near the second break region to cover the corresponding second doped structure and the second gate line, and at least exposes the second pad.

8. The gridless back-contact solar cell according to claim 1, characterized in that, In the thickness direction of the substrate layer, the surface of the second doped structure is relatively higher than the surface of the first doped structure.

9. The gridless back-contact solar cell according to claim 8, characterized in that, The surface of the substrate layer corresponding to the second doped structure is higher than the surface of the substrate layer corresponding to the first doped structure.

10. The gridless back-contact solar cell according to claim 8, characterized in that, Only the second doped structure forms the second interruption region, the second interruption region and the first pad point are correspondingly arranged in the first direction, the multiple first doped structures are connected by a first auxiliary doped structure formed in the second interruption region, and the multiple first pad points are adapted to be connected by a first auxiliary gate line; The first insulating layer is configured to at least cover a portion of the first doped structure corresponding to the second pad and to at least expose the first pad; in the thickness direction of the substrate layer, the surface of the second pad is relatively higher than the surface of the first insulating layer.

11. The gridless back-contact solar cell according to any one of claims 1-10, characterized in that, A solder layer is also suitable for being disposed on the first solder pad and / or the second solder pad.

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