Back contact battery and photovoltaic module

Abstract

The utility model discloses a back contact battery and a photovoltaic assembly, and relates to the field of photovoltaic technology. The method is used for reducing the process difficulty of forming a patterned first transparent conductive layer during mass production and is beneficial to prolonging the service life of a screen printing plate for manufacturing the patterned first transparent conductive layer. The back contact battery comprises a semiconductor substrate, a first doped semiconductor part, a second doped semiconductor part and a first transparent conductive layer. The second doped semiconductor portion is disposed on the second region and extends to cover the first doped semiconductor portion in the overlapping region. The first transparent conductive layer is disposed on the second doped semiconductor portion. A partial region in the overlapping region is a reverse electric leakage region. And a first transparent conductive layer extending from the second region is arranged in the reverse electric leakage region. The side line of the side, close to the first area, of the first transparent conducting layer is a first side line, the first side line is of a periodically repeated convex-concave alternating structure, and transition lines between convex and concave in the convex-concave alternating structure are not parallel to the first direction.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic technology, and in particular to a back contact battery and a photovoltaic module. Background Technology

[0002] Back-contact solar cells are solar cells with no electrodes on the light-facing side, and both the positive and negative electrodes are located on the back-facing side of the cell. This reduces the shading of the cells by the electrodes, increases the short-circuit current, and improves the energy conversion efficiency of the cells.

[0003] During actual use, back-contact solar cells may be obstructed by objects such as bird droppings, leaves, and dust. This obstruction can cause the cells to overheat and develop hot spots. If the temperature of these hot spots exceeds a certain threshold, it can lead to problems such as photovoltaic module delamination, backsheet burning, and glass shattering, ultimately rendering the entire solar cell unusable. In severe cases, it can even pose a fire risk. Utility Model Content

[0004] The purpose of this invention is to provide a back-contact battery and photovoltaic module to reduce the risk of hot spots in the back-contact battery. Furthermore, it helps to reduce the difficulty of forming a patterned first transparent conductive layer during mass production, and also helps to extend the lifespan of the screen used to manufacture the patterned first transparent conductive layer.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a back-contact battery. The back-contact battery includes: a semiconductor substrate, a first doped semiconductor portion, a second doped semiconductor portion, and a first transparent conductive layer. The second doped semiconductor portion and the first doped semiconductor portion have opposite conductivity types. The semiconductor substrate includes opposing first and second surfaces. The first surface includes a plurality of first regions and a plurality of second regions, as well as an overlapping region located between the first and second regions. The first regions, the overlapping region, and the second regions are arranged along a first direction. The first doped semiconductor portion is disposed in the first regions and the overlapping region.

[0006] The second doped semiconductor portion is disposed on the second region and extends to cover the first doped semiconductor portion located in the overlapping region.

[0007] A first transparent conductive layer is disposed on a second doped semiconductor portion. A portion of the overlapping region is a reverse leakage region. Within the reverse leakage region, a first transparent conductive layer extending from the second region is disposed, and the first transparent conductive layer is electrically connected to the first doped semiconductor portion via the second doped semiconductor portion. The edge of the first transparent conductive layer near the first region is a first edge line, which has a periodically repeating alternating convex and concave structure. The transition lines between the convex and concave sections in the alternating convex and concave structure are not parallel to the first direction.

[0008] With the above technical solution, when the back contact battery is in operation, the first doped semiconductor portion and the second doped semiconductor portion can effectively shunt carriers, which is beneficial for forming photocurrent. The first transparent conductive layer covering the second doped semiconductor portion has high conductivity, which can promptly discharge the carriers collected by the second doped semiconductor portion, thus facilitating carrier collection. The second doped semiconductor portion is not only disposed on the second region but also extends to cover the first doped semiconductor portion in the overlapping region. Furthermore, a portion of the overlapping region is a reverse leakage region. In this reverse leakage region, the portion of the first transparent conductive layer extending from the second region into the overlapping region can be electrically connected to the first doped semiconductor portion, which has an opposite conductivity type, through the second doped semiconductor portion. At this time, the overlapping portion of the first and second doped semiconductor portions forms a built-in diode structure with a low reverse breakdown voltage. When the back contact battery is blocked, the leakage current flows through the overlapping portion of the first and second doped semiconductor portions, then through the first transparent conductive layer, and is discharged through the electrode in contact with it. It should be noted that in the reverse leakage region, the aforementioned first transparent conductive layer is electrically connected to the first doped semiconductor portion, which has the opposite conductivity type, through the second doped semiconductor portion. This electrical connection does not include electrical connections achieved through the semiconductor substrate. It is understood that the second doped semiconductor portion and the first doped semiconductor portion can also be electrically connected through a tunneling mechanism or a thin dielectric layer.

[0009] Furthermore, in the back contact battery provided by this invention, only a portion of the overlapping area is a reverse leakage region, meaning that a portion of the overlapping area is a non-reverse leakage region. This facilitates control over the effective leakage contact area between the first doped semiconductor portion and the second doped semiconductor portion, reducing carrier recombination between the first and second doped semiconductor portions in the forward voltage region, thereby contributing to higher conversion efficiency of the back contact battery. In addition, the first edge of the first transparent conductive layer near the first region has a periodically repeating convex-concave alternating structure. On one hand, the concave portion can control the effective leakage contact area between the first and second doped semiconductor portions; on the other hand, it facilitates the uniform distribution of the reverse leakage region with the convex portion of the first transparent conductive layer along the periodic repeating direction of the convex-concave alternating structure in the overlapping area. This, in turn, helps to evenly distribute the heat generated when the back contact battery is shielded throughout the entire battery area, preventing localized heat accumulation that could lead to reliability issues and improving the back contact battery's resistance to burnout. Secondly, in the above-mentioned alternating convex and concave structure, the transition line between the convex and concave parts is not parallel to the first direction. At this time, the screen used to form the patterned first transparent conductive layer also does not have an outline line parallel to the first direction in its pattern outline. This improves the structural strength of the screen along the first direction and prevents damage to its morphology due to repeated use of the screen during mass production, which would affect the forming accuracy of the first transparent conductive layer near the first edge line. This is beneficial for achieving a higher yield of the back contact battery, while also extending the service life of the screen and controlling the manufacturing cost of the back contact battery.

[0010] In one possible implementation, the transition line is a curve or an oblique line. In this case, the transition line can be not only a curve with a bend, but also a straight or nearly straight oblique line, with various examples. The specific shape of the transition line can be set according to different needs, improving the applicability of the back contact battery provided by this invention in different application scenarios. Furthermore, it can reduce the manufacturing difficulty of the back contact battery.

[0011] In one possible implementation, the first edge line is a wavy line, a zigzag line, or a trapezoidal broken line. The principle behind the beneficial effects in this case can be referenced from the principle behind the beneficial effects of transition lines being curves or oblique lines, as described above, and will not be repeated here.

[0012] In one possible implementation, when the transition line is a diagonal line, the angle between the diagonal line and the first direction is greater than or equal to 5° and less than or equal to 85°.

[0013] With the above technical solution, it is understood that, since the width of the reverse leakage region along the first direction and other factors are the same, when the transition line is a diagonal line, the angle between the diagonal line and the first direction will affect the area of ​​the reverse leakage region. Therefore, when the angle between the diagonal line and the first direction is within the aforementioned range, it is beneficial to control the effective leakage contact area of ​​the reverse leakage region within a reasonable range, which is beneficial for balancing the burn-out resistance and conversion efficiency of the back contact battery. Simultaneously, the angle between the diagonal line and the first direction being within the aforementioned range also allows the outline of the screen used to form the patterned first transparent conductive layer to form a triangular shape with high structural stability, similar to its other parts. This further strengthens the structural strength of the screen along the first direction and helps to improve the lifespan of the screen.

[0014] In one possible implementation, within a unit length of 1 cm along the length extension direction of the first side line, the number of convex and concave structures is greater than or equal to 1 and less than or equal to 200.

[0015] With the above technical solution, it is understood that the number of protrusions and concaves in the alternating convex-concave structure per unit length affects the density of the protrusions, i.e., the density of the reverse leakage area in the overlapping area. Therefore, when the number of protrusions and concaves in the alternating convex-concave structure is within the above range per 1cm unit length, it can prevent excessive heat concentration when the back contact battery is blocked due to an insufficient number of protrusions and concaves, resulting in a small proportion of the reverse leakage area in the alternating area. This extends the lifespan of the screen and further improves the burn-out resistance of the back contact battery. Additionally, it can prevent damage such as excessive pressure from the etching paste on the contour lines corresponding to the first edge line of the screen due to an excessive number of protrusions and concaves in the alternating convex-concave structure, thus reducing the risk of hot spots on the back contact battery and extending the lifespan of the screen.

[0016] In one possible implementation, multiple reverse leakage regions are spaced apart along a second direction in the overlapping region, and the second direction intersects with the first direction. In this case, the distribution of the first transparent conductive layer in the overlapping region along the second direction can be provided as an implementation method. At this time, not only can the reverse breakdown voltage and forward carrier recombination loss of the back contact battery be controlled by adjusting the width of the first transparent conductive layer in the overlapping region along the first direction, but also the reverse breakdown voltage and forward carrier recombination loss of the back contact battery can be controlled by adjusting the length of the continuous and discontinuous portions of the first transparent conductive layer in the overlapping region along the second direction, thereby improving the applicability of the back contact battery provided by this invention in different application scenarios.

[0017] In one possible implementation, the recess of the first edge extends into the second region.

[0018] In the above-described technical solution, the second doped semiconductor portion is not only disposed on the second region but also extends to cover the first doped semiconductor portion on the overlapping region. In this case, the second doped semiconductor portion is located not only on the side of the first doped semiconductor portion on the overlapping region away from the semiconductor substrate but also on the sidewall of the first doped semiconductor portion on the overlapping region. Furthermore, the first transparent conductive layer is located on the second doped semiconductor portion, allowing it to contact the second doped semiconductor portion disposed on the sidewall of the first doped semiconductor portion on the overlapping region. In this case, when the recess of the first edge extends into the second region, it ensures that the first transparent conductive layer disposed in the second region will not be electrically connected to the second doped semiconductor portion at the recess. This ensures that the contact area between the second doped semiconductor portion and the first transparent conductive layer in the reverse leakage region can be effectively adjusted by adjusting the length of the disconnected and continuous portions of the first transparent conductive layer along the second direction, thereby achieving precise control of the reverse breakdown voltage and forward carrier recombination loss of the back contact battery. At the same time, in the actual application manufacturing process, there is no need to strictly require the screen printing precision and the placement precision (i.e., alignment precision) of the screen printing on one side of the battery in order to achieve the patterned first transparent conductive layer, which helps to reduce the manufacturing difficulty of the back contact battery.

[0019] In one possible implementation, a second region of the semiconductor substrate is recessed into the semiconductor substrate relative to the overlapping region. A step is formed at the intersection of the second region and the overlapping region. A first edge line crosses the step along a first direction.

[0020] With the above technical solution, the second region of the semiconductor substrate is recessed into the semiconductor substrate relative to the overlapping region. This helps to prevent the presence of a first doped semiconductor portion with a conductivity type opposite to that of the second doped semiconductor portion in the second region, thereby further reducing the carrier recombination rate on the first side of the back contact cell and improving the conversion efficiency of the back contact cell. Furthermore, the first edge line crosses the step formed by the second region and the overlapping region along the first direction. Since the transition line in the first edge line is not parallel to the first direction, this further reduces the overflow of etching paste at the step, which helps improve the printing accuracy of the screen. Simultaneously, reusable screens are more prone to damage at the step; the transition line of the first edge line crossing the step at an angle helps reduce damage at the step.

[0021] In one possible implementation, the ratio of the width of at least one reverse leakage region in the first direction to the width of the overlapping region in the first direction is greater than or equal to 0.5% and less than or equal to 100%.

[0022] With the above technical solution, all other factors being equal, the width of the reverse leakage region in the first direction affects the effective leakage contact area and the magnitude of the leakage current. Therefore, when the ratio of the width of at least one reverse leakage region in the first direction to the width of the overlapping region in the first direction is within the aforementioned range, the width of the reverse leakage region in the first direction has a relatively large selectable range. In this case, when the back contact battery provided by this invention is installed in an environment with few obstructions such as bird droppings, leaves, or sand, the width of the reverse leakage region in the first direction can be set within a smaller range to reduce the recombination rate of carriers with opposite conductivity types between the first and second doped semiconductor portions within the reverse leakage region. This helps to reduce carrier recombination losses in the forward voltage region of the back contact battery, ensuring high operating efficiency. Conversely, when the back contact battery provided by this invention is installed in an environment with many obstructions such as bird droppings, leaves, or sand, the width of the reverse leakage region in the first direction can be set within a larger range to improve the conductivity of the second doped semiconductor portion. This helps to reduce the reverse breakdown voltage of the back contact battery, ensuring a lower risk of hot spots. Therefore, the width of the reverse leakage area in the first direction can be set according to different environmental requirements, thereby improving the applicability of the back contact battery provided by this utility model in different practical application scenarios.

[0023] In one possible implementation, the back contact battery further includes a second transparent conductive layer disposed on the first doped semiconductor portion. The first and second transparent conductive layers are physically insulated from each other.

[0024] When the above technical solution is adopted, the presence of the second transparent conductive layer can reduce the contact barrier between the first doped semiconductor part and the corresponding electrode, improve the contact performance between the two, and help to further improve the conversion efficiency of the back contact battery.

[0025] In one possible implementation, the second transparent conductive layer extends from the first region and covers a portion of the second doped semiconductor portion located in the overlapping region. In this case, it can be ensured that the second transparent conductive layer covers all portions of the first doped semiconductor portion located in the first region, which is beneficial for improving carrier collection efficiency. Furthermore, it eliminates the need for strict control over manufacturing precision to align the edge of the second transparent conductive layer with the boundary between the first region and the overlapping region, reducing the manufacturing difficulty of the back contact cell.

[0026] In one possible implementation, the edge of the second transparent conductive layer near the second region is designated as the second edge, which can be a straight line, a diagonal line, a zigzag line, a trapezoidal zigzag line, or a wavy line. The application principle of the beneficial effect in this case can be referenced to the application principle of the beneficial effect of the first edge being a wavy line, a zigzag line, or a trapezoidal zigzag line as described above, and will not be repeated here.

[0027] In one possible implementation, the back contact battery further includes a first interface passivation layer located between the first doped semiconductor portion and the semiconductor substrate. The back contact battery also includes a second interface passivation layer, which is located at least between the second doped semiconductor portion and the semiconductor substrate. The first interface passivation layer and the first doped semiconductor portion constitute a first passivated contact structure, and the second interface passivation layer and the second doped semiconductor portion constitute a second passivated contact structure. The first passivated contact structure is a tunneling passivated contact structure. The second passivated contact structure is a heterogeneous contact structure. In this case, it is beneficial to reduce carrier recombination in the forward voltage region of the back contact battery, and simultaneously improve the structural yield of the back contact battery.

[0028] Secondly, this utility model provides a photovoltaic module. The photovoltaic module includes the back-contact battery provided in the first aspect and its various implementations described above.

[0029] The beneficial effects of the second aspect and its various implementations in this utility model can be analyzed with reference to the beneficial effects of the first aspect and its various implementations, and will not be repeated here. Attached Figure Description

[0030] The accompanying drawings, which are included to provide a further understanding of the present invention and constitute a part of this invention, illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the present invention and do not constitute an undue limitation thereof. In the drawings:

[0031] Figure 1 A longitudinal sectional view of the back contact battery provided in an embodiment of this utility model. Figure 1 ;

[0032] Figure 2 Top view of the structure of the back contact battery provided in the embodiment of this utility model Figure 1 ;

[0033] Figure 3 Top view of the structure of the back contact battery provided in the embodiment of this utility model Figure 2 ;

[0034] Figure 4 A longitudinal sectional view of the back contact battery provided in an embodiment of this utility model. Figure 2 ;

[0035] Figure 5 A longitudinal sectional view of the back contact battery provided in an embodiment of this utility model. Figure 3 ;

[0036] Figure 6 A longitudinal sectional view of the back contact battery provided in an embodiment of this utility model. Figure 4 ;

[0037] Figure 7 Top view of the structure of the back contact battery provided in the embodiment of this utility model Figure 3 ;

[0038] Figure 8 Top view of the structure of the back contact battery provided in the embodiment of this utility model Figure 4 ;

[0039] Figure 9 Top view of the structure of the back contact battery provided in the embodiment of this utility model Figure 5 ;

[0040] Figure 10 Top view of the structure of the back contact battery provided in the embodiment of this utility model Figure 6 ;

[0041] Figure 11 Top view of the structure of the back contact battery provided in the embodiment of this utility model Figure 7 ;

[0042] Figure 12 A longitudinal sectional view of the back contact battery provided in an embodiment of this utility model. Figure 5 ;

[0043] Figure 13 A longitudinal sectional view of the back contact battery provided in an embodiment of this utility model. Figure 6 ;

[0044] Figure 14 Top view of the structure of the back contact battery provided in the embodiment of this utility model Figure 8 ;

[0045] Figure 15 Top view of the structure of the back contact battery provided in the embodiment of this utility model Figure 9 ;

[0046] Figure 16 This is a top view of the structure of the back contact battery provided as a comparative example of this utility model.

[0047] Reference numerals: 11 is a semiconductor substrate, 12 is a first doped semiconductor portion, 13 is a second doped semiconductor portion, 14 is a first transparent conductive layer, 15 is a first region, 16 is a second region, 17 is an overlapping region, 18 is a first edge line, 19 is a concave portion, 20 is a convex portion, 21 is a second transparent conductive layer, 22 is a second edge line, 23 is a first electrode, 24 is a second electrode, 25 is a first interface passivation layer, 26 is a second interface passivation layer, and 27 is a surface passivation layer. Detailed Implementation

[0048] To make the technical problems, technical solutions, and beneficial effects of this utility model clearer, the present utility model 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 merely illustrative of the present utility model and are not intended to limit the present utility model.

[0049] 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.

[0050] 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 utility model, "a plurality of" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0051] In the description of this utility model, 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 utility model 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 utility model.

[0052] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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 utility model according to the specific circumstances.

[0053] Firstly, embodiments of this utility model provide a back-contact battery. For example... Figures 1 to 3As shown, the back contact battery includes: a semiconductor substrate 11, a first doped semiconductor portion 12, a second doped semiconductor portion 13, and a first transparent conductive layer 14. The second doped semiconductor portion 13 and the first doped semiconductor portion 12 have opposite conductivity types. The semiconductor substrate 11 includes opposing first and second surfaces. The first surface includes a plurality of first regions 15 and a plurality of second regions 16, and an overlapping region 17 located between the first regions 15 and the second regions 16. The first regions 15, the overlapping region 17, and the second regions 16 are arranged along a first direction. The first doped semiconductor portion 12 is disposed on the first regions 15 and the overlapping region 17. The second doped semiconductor portion 13 is disposed on the second regions 16 and extends to cover the first doped semiconductor portion 12 located in the overlapping region 17. The first transparent conductive layer 14 is disposed on the second doped semiconductor portion 13.

[0054] Among them, a portion of the overlapping region 17 is a reverse leakage region. In the reverse leakage region, a first transparent conductive layer 14 extending from the second region 16 is provided, and the first transparent conductive layer 14 is electrically connected to the first doped semiconductor section 12 through the second doped semiconductor section 13.

[0055] When the back-contact battery is in operation, the first and second doped semiconductor portions can effectively shunt charge carriers, facilitating the formation of photocurrent. The first transparent conductive layer covering the second doped semiconductor portion has high conductivity, which can promptly drain the charge carriers collected by the second doped semiconductor portion, thus promoting carrier collection. Figures 1 to 3As shown, the second doped semiconductor portion 13 is not only disposed on the second region 16, but also extends to cover the first doped semiconductor portion 12 in the overlapping region 17. Furthermore, a portion of the overlapping region 17 is a reverse leakage region. In this reverse leakage region, the portion of the first transparent conductive layer 14 extending from the second region 16 into the overlapping region 17 can be electrically connected through the second doped semiconductor portion 13 to the first doped semiconductor portion 12, which has an opposite conductivity type. At this time, the overlapping portion of the first doped semiconductor portion 12 and the second doped semiconductor portion 13 forms a built-in diode structure with a low reverse breakdown voltage. When the back contact battery is blocked, the leakage current (it should be emphasized that, for convenience and clarity, when the leakage current mentioned in the embodiments of this utility model is...) The term "transmission method" encompasses not only the transmission path but also the transmission direction. However, it does not mean that the transmission direction of the leakage current can only be the single direction described. When the conductivity type of the first doped semiconductor portion 12 and the second doped semiconductor portion 13 changes, the transmission direction of the leakage current can also be opposite to the direction described. That is, in this embodiment of the present invention, only the transmission path of the leakage current is limited, not the transmission direction. The leakage current is discharged through the overlapping portion of the first doped semiconductor portion 12 and the second doped semiconductor portion 13, then through the first transparent conductive layer 14, and through the electrode in contact with it. It should be noted that in the reverse leakage region, the first transparent conductive layer 14 is electrically connected to the first doped semiconductor portion 12, which has the opposite conductivity type, through the second doped semiconductor portion 13. This electrical connection does not include electrical connections achieved through the semiconductor substrate 11. It is understood that the second doped semiconductor portion 13 and the first doped semiconductor portion 12 can also be electrically connected through a tunneling mechanism or a thin dielectric layer.

[0056] Among them, the edge line of the first transparent conductive layer 14 near the first region 15 is the first edge line 18. The first edge line 18 has a periodically repeating convex-concave alternating structure. The transition line between the convex and concave in the convex-concave alternating structure is not parallel to the first direction.

[0057] like Figures 1 to 3As shown, in the back contact battery provided in this embodiment of the present invention, only a portion of the overlapping region 17 is a reverse leakage region, that is, a portion of the overlapping region 17 is a non-reverse leakage region. This is beneficial for controlling the effective leakage contact area between the first doped semiconductor portion 12 and the second doped semiconductor portion 13, reducing the carrier recombination rate between the first doped semiconductor portion 12 and the second doped semiconductor portion 13 when the back contact battery is in the forward voltage region, thereby contributing to a higher conversion efficiency of the back contact battery. In addition, the first edge 18 of the first transparent conductive layer 14 near the first region 15 has a periodically repeating convex-concave alternating structure. On the one hand, the concave portion 19 in the convex-concave alternating structure can be used to control the effective leakage contact area between the first doped semiconductor portion 12 and the second doped semiconductor portion 13. On the other hand, it is beneficial for the reverse leakage region of the convex portion 20 of the first transparent conductive layer 14 to be evenly distributed in the overlapping region 17 along the periodic repeating direction of the convex-concave alternating structure. This is beneficial for the heat generated when the back contact battery is shielded to be evenly distributed throughout the battery area, preventing local heat accumulation and reliability problems, and improving the burn-out resistance of the back contact battery. Secondly, the patterning process of the first transparent conductive layer generally involves screen printing and etching the paste. In the aforementioned alternating convex and concave structure, the transition lines between the convex and concave sections are not parallel to the first direction. Therefore, the screen used to form the patterned first transparent conductive layer 14 also lacks outlines parallel to the first direction in its pattern contour. This improves the structural strength of the screen along the first direction, preventing damage to its morphology during mass production due to repeated use of the screen, which would affect the forming accuracy of the first transparent conductive layer 14 near the first edge line 18. This contributes to a higher yield rate for the back contact battery, extends the lifespan of the screen, and helps control the manufacturing cost of the back contact battery.

[0058] In practical applications, this embodiment of the invention does not specifically limit the material and conductivity type of the semiconductor substrate. For example, the semiconductor substrate can be a silicon substrate. Alternatively, the semiconductor substrate can be any semiconductor material such as a germanium-silicon substrate, a germanium substrate, or a gallium arsenide substrate.

[0059] Secondly, the aforementioned semiconductor substrate includes a first surface and a second surface opposite to each other. The first surface of the semiconductor substrate corresponds to the back-lighting surface of the back contact battery, and the second surface of the semiconductor substrate corresponds to the light-facing surface of the back contact battery. The distribution of the first region, second region, and overlapping region on the first surface can be determined based on the distribution of the first doped semiconductor portion and the second doped semiconductor portion formed on one side of the first surface. Specifically, since the first doped semiconductor portion of the back contact battery is disposed in the first region and the overlapping region, the distribution range of the first region and the overlapping region on the first surface can be determined according to the distribution requirements of the first doped semiconductor portion in the actual application scenario. Since a portion of the second doped semiconductor portion of the back contact battery is disposed on the second region of the first surface, the distribution range of the second region on the first surface can be determined according to the distribution requirements of the second doped semiconductor portion on the semiconductor substrate in the actual application scenario.

[0060] It is understandable that the first region roughly corresponds to the first emitter region, and the second region roughly corresponds to the second emitter region; one of the first region and the second region is a P region, and the other is an N region, while the overlapping region is a PN overlapping region.

[0061] The shapes of the first, second, and third regions are determined by actual needs. For example, the first and second regions can be distributed in alternating stripe patterns or in alternating interdigitated patterns.

[0062] The arrangement direction (i.e., the first direction) of the first region, overlapping region, and second region can be determined based on the distribution of the first region, second region, and overlapping region on the first surface, and is not specifically limited here. For example, when the first region and second region are distributed in alternating strip-like patterns, the first direction is parallel to the arrangement direction of the two adjacent strip-like regions. Another example: when the first region and second region are distributed in alternating interdigitated patterns, the first direction is parallel to the arrangement direction of the two adjacent U-shaped regions.

[0063] From the perspective of surface morphology, such as Figure 1 As shown, the first and second surfaces of the semiconductor substrate 11 can be planar. Alternatively, as... Figure 4 As shown, the second surface of the semiconductor substrate 11 can also be textured to improve the light-trapping effect of the second surface and increase the utilization rate of light by the semiconductor substrate 11. Secondly, the surface of the second region 16 of the first surface can also be textured to increase the contact area between the second doped semiconductor portion 13 on the second region 16 and the first transparent conductive layer 14 on the second region 16, and to increase the contact area between the first transparent conductive layer 14 on the second region 16 and the corresponding electrode, which helps to reduce transmission loss.

[0064] Secondly, such as Figure 1As shown, in the first surface, the surface of the second region 16 can be flush with both the first region 15 and the overlapping region 17. Alternatively, as... Figure 5 As shown, the second region 16 of the semiconductor substrate 11 can be recessed into the semiconductor substrate 11 relative to the overlapping region 17. In this case, a step is formed between the second region 16 and the overlapping region 17. Because the second region 16 of the semiconductor substrate 11 is recessed into the semiconductor substrate 11 relative to the overlapping region 17, no first doped semiconductor portion 12 with a conductivity type opposite to the second doped semiconductor portion 13 remains on the second region 16. This facilitates further reducing the carrier recombination rate on the first side of the back contact cell and improving the conversion efficiency of the back contact cell.

[0065] The height difference between the surface of the second region and the surface of the overlapping region can be set according to actual needs, and no specific limitation is made here.

[0066] Regarding the first doped semiconductor portion, in terms of conductivity type, this embodiment of the invention does not specifically limit the conductivity type of the first doped semiconductor portion, as long as the conductivity types of the first doped semiconductor portion and the second doped semiconductor portion are opposite. Specifically, the conductivity type of the first doped semiconductor portion can be N-type, in which case the conductivity type of the second doped semiconductor portion is P-type; or, the conductivity type of the first doped semiconductor portion can also be P-type, in which case the conductivity type of the second doped semiconductor portion is N-type.

[0067] In terms of formation location, such as Figure 1 As shown, the first doped semiconductor portion 12 can be disposed on the first region 15 and the overlapping region 17 of the semiconductor substrate 11; or, as... Figure 6 As shown, the first doped semiconductor portion 12 can also be disposed within the first region 15 and the overlapping region 17 of the semiconductor substrate 11. In this case, it can be formed by diffusion or ion implantation.

[0068] When the first doped semiconductor portion is disposed on the first region and the overlapping region of the semiconductor substrate, the material of the first doped semiconductor portion may include any semiconductor material such as silicon, silicon germanium, germanium, or gallium arsenide. In terms of the arrangement of matter, the crystal phase of the first doped semiconductor portion may be amorphous, microcrystalline, nanocrystalline, single crystal, or polycrystalline.

[0069] Secondly, such as Figure 1 As shown, the first doped semiconductor portion 12 can be directly disposed on the first region 15 and the overlapping region 17. Alternatively, as... Figure 5As shown, the aforementioned back contact battery may further include a first interface passivation layer 25 located between the first doped semiconductor portion 12 and the semiconductor substrate 11. In this case, the passivated contact structure formed by the first interface passivation layer 25 and the first doped semiconductor portion 12 has excellent interface passivation effect and can achieve selective collection of charge carriers, reducing the carrier recombination rate of the first region 15 and the overlapping region 17 on the first surface of the semiconductor substrate 11, and further improving the photoelectric conversion efficiency of the back contact battery. The material and thickness of the first interface passivation layer 25 can be set according to the material of the first doped semiconductor portion 12 and actual needs, and are not specifically limited here. For example, when the material of the first doped semiconductor portion is doped polycrystalline silicon, the first interface passivation layer is a tunneling passivation layer. As another example, when the material of the first doped semiconductor portion includes at least one of doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon, the first interface passivation layer is an intrinsic amorphous silicon layer, an intrinsic microcrystalline silicon layer, an intrinsic nanocrystalline silicon layer, or a mixture of the above three.

[0070] For example, the thickness of the first doped semiconductor portion can be greater than or equal to 50 nm and less than or equal to 200 nm. For instance, the thickness of the first doped semiconductor portion can be 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 150 nm, 180 nm, or 200 nm. In this case, the thickness of the first doped semiconductor portion within the above range can prevent a lower field passivation effect due to a smaller layer thickness; it can also prevent a larger material consumption for manufacturing the first doped semiconductor portion due to a larger thickness, thus helping to control the manufacturing cost of the back contact battery. Furthermore, the thickness of the first doped semiconductor portion affects the mating height between the side surfaces of the first and second doped semiconductor portions, which in turn affects the junction area of ​​the PN junction formed between the first and second doped semiconductor portions in the reverse leakage region. Based on this, when the thickness of the first doped semiconductor portion is within the above-mentioned range, it can also prevent the leakage current of the first doped semiconductor portion and the second doped semiconductor portion at the side joint from being too large due to the large thickness of the first doped semiconductor portion resulting in a large docking height. This ensures that the leakage loss and reverse breakdown voltage of the back contact battery can be effectively controlled by adjusting the width of the first transparent conductive layer in the first direction and the width of the overlapping area in the first direction, so that the back contact battery has high working performance and working reliability.

[0071] For example, the doping concentration of the dopant in the first doped semiconductor portion can be greater than or equal to 1E19 cm⁻¹. -3 And less than or equal to 5E20cm -3 For example, the doping concentration of the dopant in the first doped semiconductor section can be 1E19cm⁻¹.-3 2E19cm -3 4E19cm -3 6E19cm -3 8E19cm -3 1E20cm -3 3E20cm -3 Or 5E20cm -3 In this case, the doping concentration of the dopant in the first doped semiconductor portion is within the aforementioned range. This prevents a low doping concentration of the dopant in the first doped semiconductor portion from causing a low field passivation effect on the semiconductor substrate, ensuring that the first region and overlapping region of the back contact battery have a relatively low carrier recombination rate under normal operating conditions. Simultaneously, it also facilitates good conductivity in the first doped semiconductor portion, ensuring a relatively low transmission resistance in the reverse leakage region of the first doped semiconductor portion when the back contact battery is shielded, further reducing the reverse breakdown voltage of the back contact battery. Furthermore, it prevents a high doping concentration of the dopant in the first doped semiconductor portion from causing a high difficulty in doping the intrinsic semiconductor layer used to manufacture the first doped semiconductor portion, reducing process difficulty and improving the yield of the back contact battery.

[0072] Regarding the aforementioned second-doped semiconductor section, in terms of materials, the material of the second-doped semiconductor section can include any semiconductor material such as silicon, germanium-silicon, germanium, or gallium arsenide. In terms of the arrangement of matter, the crystal phase of the second-doped semiconductor section can be amorphous, microcrystalline, nanocrystalline, single crystal, or polycrystalline.

[0073] In terms of doping, the present invention does not specifically limit the doping concentration of the dopant in the second doped semiconductor section, as long as it can be applied to the back contact battery provided in the present invention.

[0074] For example, the doping concentration of the dopant in the second doped semiconductor portion can be greater than or equal to 1E19 cm⁻¹. -3 And less than or equal to 5E20cm -3 For example, the doping concentration of the dopant in the second doped semiconductor section can be 1E19cm⁻¹. -3 2E19cm -3 4E19cm -3 6E19cm -3 8E19cm -3 1E20cm -3 3E20cm -3 Or 5E20cm -3In this case, the doping concentration of the dopant in the second doped semiconductor is within the aforementioned range. This prevents a low doping concentration in the second doped semiconductor from causing a low field passivation effect on the semiconductor substrate, ensuring that the second region of the back contact battery has a relatively low carrier recombination rate under normal operating conditions. Simultaneously, it also facilitates good conductivity in the second doped semiconductor, ensuring a relatively low transmission resistance in the reverse leakage region when the back contact battery is shielded, further reducing the reverse breakdown voltage of the back contact battery. Furthermore, it prevents a high doping concentration in the second doped semiconductor from making the intrinsic semiconductor layer used to manufacture the second doped semiconductor more difficult to dope, thus improving the yield of the back contact battery.

[0075] Regarding the layer thickness, this embodiment of the invention does not specifically limit the thickness of the second doped semiconductor portion. For example, the thickness of the second doped semiconductor portion can be greater than or equal to 5 nm and less than or equal to 50 nm. For instance, the thickness of the second doped semiconductor portion can be 5 nm, 10 nm, 15 nm, 20 nm, 30 nm, 40 nm, or 50 nm, etc. The application principle of the beneficial effects in this case is the same as the application principle of the beneficial effects of the first doped semiconductor portion having a thickness greater than or equal to 50 nm and less than or equal to 200 nm as described above, and will not be repeated here.

[0076] In terms of formation location, such as Figure 1 As shown, the second doped semiconductor portion 13 can be directly disposed on the first doped semiconductor portion 12 in the second region 16 and extending to cover the overlapping region 17. Alternatively, as... Figure 5 As shown, the aforementioned back contact battery may further include a second interface passivation layer 26, which is located between the second region 16 and the second doped semiconductor portion 13 on the first surface, and extends between the second doped semiconductor portion 13 and the first doped semiconductor portion 12. In this case, the passivated contact structure formed by the second interface passivation layer 26 and the portion of the second doped semiconductor portion 13 located on the second region 16 can achieve selective collection of charge carriers and reduce the carrier recombination rate of the second region 16 on the first surface of the semiconductor substrate 11. The material and thickness of the second interface passivation layer 26 can be set according to the material of the second doped semiconductor portion 13 and actual needs, and are not specifically limited here. For example, when the material of the second doped semiconductor portion is doped polycrystalline silicon, the second interface passivation layer is a tunneling passivation layer. As another example, when the material of the second doped semiconductor portion includes doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon, the second interface passivation layer is an intrinsic amorphous silicon layer, an intrinsic microcrystalline silicon layer, an intrinsic nanocrystalline silicon layer, or a mixture of the above three layers.

[0077] As for the thickness of the second interface passivation layer, since the thickness of the second interface passivation layer will affect its own transmission resistance and passivation effect, and thus affect the forward leakage loss and reverse breakdown voltage of the back contact battery, the thickness of the second interface passivation layer can be determined according to the requirements of the forward leakage loss and reverse breakdown voltage of the back contact battery in the actual application scenario. No specific limit is made here.

[0078] For example, the thickness of the second interface passivation layer can be greater than or equal to 2 nm and less than or equal to 20 nm. For instance, the thickness of the second interface passivation layer can be 2 nm, 5 nm, 8 nm, 10 nm, 12 nm, 15 nm, 18 nm, or 20 nm, etc. In this case, based on this, the thickness of the second interface passivation layer within the above range helps to prevent a poor passivation effect on the second region due to a small thickness of the second interface passivation layer, ensuring a low carrier recombination rate on the surface of the second region. It also prevents a large thickness of the second interface passivation layer from causing a large transmission resistance, which would result in low carrier collection efficiency of the second doped semiconductor portion under normal operation of the back contact battery, and a smaller reduction in reverse breakdown voltage when the back contact battery is blocked, further facilitating a balance between the reverse breakdown voltage and operating efficiency of the back contact battery.

[0079] In addition, when the back contact battery includes a first interface passivation layer and a second interface passivation layer, the first interface passivation layer and the first doped semiconductor portion constitute a first passivation contact structure, and the second interface passivation layer and the second doped semiconductor portion constitute a second passivation contact structure.

[0080] The passivation contact types of the first passivation contact structure and the second passivation contact structure can be the same. For example, both the first passivation contact structure and the second passivation contact structure can be tunneling passivation contact structures or heterogeneous contact structures. Alternatively, the passivation contact types of the first passivation contact structure and the second passivation contact structure can be different. For example, one of the first passivation contact structure and the second passivation contact structure can be a tunneling passivation contact structure, and the other can be a heterogeneous contact structure. In this case, when the passivation contact types of the first passivation contact structure and the second passivation contact structure are different, the passivation contact types of the first passivation contact structure and the second passivation contact structure can be adjusted according to different actual application scenarios to improve the applicability of the back contact battery provided by this utility model embodiment in different application scenarios.

[0081] Regarding the first transparent conductive layer mentioned above, this embodiment of the invention does not specifically limit the material and thickness of the first transparent conductive layer.

[0082] For example, the material of the first transparent conductive layer may include at least one of fluorine-doped tin oxide, aluminum-doped zinc oxide, tin-doped indium oxide, tungsten-doped indium oxide, molybdenum-doped indium oxide, cerium-doped indium oxide, and indium hydroxide.

[0083] For example, the thickness of the first transparent conductive layer can be greater than or equal to 10 nm and less than or equal to 100 nm.

[0084] As for the specific morphology of the first edge line and transition line of the first transparent conductive layer, it can be determined according to the actual application scenario. As long as the first edge line has a periodically repeating alternating convex and concave structure, and the transition line between the convex and concave in the alternating convex and concave structure is not parallel to the first direction, it is acceptable.

[0085] For example, such as Figure 2 and Figure 3 As shown, the transition line can be a curve or a slant line. In this case, the transition line can be not only a curve with a bend, but also a straight or nearly straight slant line, with various examples. The specific shape of the transition line can be set according to different needs, improving the applicability of the back contact battery provided by this utility model embodiment in different application scenarios. Furthermore, it can reduce the manufacturing difficulty of the back contact battery. The curve mentioned above can be an arc or a non-arc line with a bend. The angle and magnitude of the curve can be determined according to the requirements of the hot spot risk and conversion efficiency of the back contact battery in the actual application scenario, as well as the requirements of the screen life for manufacturing the first transparent conductive layer 14, and are not specifically limited here.

[0086] Regarding the aforementioned diagonal line, it is understandable that, assuming other factors such as the width of the reverse leakage region along the first direction are constant, when the transition line is diagonal, the angle between the diagonal line and the first direction will affect the size of the reverse leakage region. Furthermore, the size of this angle will also affect the strength of the screen printing plate along the first direction. Based on this, the specific requirements for hot spot risk and conversion efficiency of the back contact battery, as well as the lifespan requirements for the screen printing plate used to manufacture the first transparent conductive layer, can be determined according to the actual application scenario; no specific limitations are made here.

[0087] For example, when the transition line is a diagonal line, the angle between the diagonal line and the first direction is greater than or equal to 5° and less than or equal to 85°. For instance, the angle between the diagonal line and the first direction can be 5°, 10°, 15°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, or 85°. In this case, when the angle between the diagonal line and the first direction is within the above range, it is beneficial to control the effective leakage contact area of ​​the reverse leakage region within a reasonable range, which is beneficial to the balance adjustment between the back contact battery's burn-out resistance and conversion efficiency. Simultaneously, the angle between the diagonal line and the first direction being within the above range also helps to ensure that the outline of the screen used to form the patterned first transparent conductive layer, corresponding to the first edge line, can form a similar triangular shape with high structural stability with its other parts, further strengthening the structural strength of the screen along the first direction and improving the screen's service life.

[0088] For example, such as Figures 7 to 10 As shown, the first edge line 18 can be a wavy line, a zigzag line, or a trapezoidal zigzag line. The application principle of the beneficial effect in this case can refer to the application principle of the beneficial effect of the transition line being a curve or a diagonal line as described above, and will not be repeated here. Among them, the curvature of the concave part 19 and the convex part 20 in the wavy line, the angle of each zigzag angle in the zigzag line, and the inclination angle and horizontal length of the inclined line in the trapezoidal zigzag line can be determined according to the proportion of the reverse leakage area in the overlapping area 17 in the actual application scenario, as well as the screen life of manufacturing the first transparent conductive layer 14, and are not specifically limited here.

[0089] Regarding the extension direction of the first sideline and the frequency of the convex and concave arrangement in the alternating convex-concave structure, it can be understood that since the dimensions of the convex and concave parts in the alternating convex-concave structure are constant, the number of convex and concave parts per unit length will affect the density of the convex parts, i.e., the density of the reverse leakage region in the overlapping region. Based on this, the number of convex and concave parts per unit length in the alternating convex-concave structure can be determined according to the requirements of hot spot risk and conversion efficiency of the back contact battery in the actual application scenario; no specific limit is made here.

[0090] For example, within a 1cm unit length along the length of the first edge, the number of protrusions and concaves in the alternating convex-concave structure is greater than or equal to 1 and less than or equal to 200. For instance, within a 1cm unit length along the length of the first edge, the number of protrusions and concaves in the alternating convex-concave structure can be 1, 10, 30, 50, 80, 100, 120, 150, 180, or 200, etc. In this case, it is understood that controlling the effective leakage contact area of ​​the reverse leakage region within a reasonable range can prevent the heat generated when the back contact battery is blocked due to an insufficient number of protrusions and concaves in the alternating structure, resulting in a small proportion of the reverse leakage region in the alternating area. This extends the lifespan of the screen and further improves the burn-out resistance of the back contact battery. In addition, it can prevent the risk of damage such as the etching paste squeezing the contour line corresponding to the first edge line in the screen due to the large number of protrusions and concavities in the alternating structure. This helps to reduce the risk of hot spots on the back contact battery and extend the service life of the screen.

[0091] It should be noted that in the actual manufacturing process, because the etching paste for etching the first transparent conductive layer has a certain degree of fluidity, when manufacturing the first transparent conductive layer using a screen, after placing the etching paste on the exposed area of ​​the screen and removing the screen, the edge of the etching paste may undergo morphological changes due to its fluidity. This results in a slight change in the morphology of the first edge line of the first transparent conductive layer at the edge of the etching paste after etching. However, this slight change does not affect the macroscopic appearance of the first edge line as a periodic morphology of alternating convex and concave sections. Secondly, the curves, diagonal lines, sawtooth lines, or trapezoidal broken lines mentioned above can be... Figures 7 to 9 The regular line type shown; or, it could be as follows: Figure 10 The irregular shapes shown are generally curves, oblique lines, zigzag lines, or trapezoidal broken lines.

[0092] Furthermore, it is understandable that the width of the reverse leakage region in the first direction affects the effective leakage contact area and the magnitude of the leakage current. Specifically, the larger the width of the reverse leakage region in the first direction, the lower the hot spot risk of the back contact battery. However, in the forward voltage region, the carrier recombination rate between the first and second doped semiconductor parts of the back contact battery is higher, resulting in lower battery conversion efficiency. Therefore, the width of the reverse leakage region in the first direction and the proportion of the reverse leakage region in the overlapping region can be determined according to the hot spot risk and conversion efficiency requirements of the back contact battery in the actual application scenario; no specific limitations are made here.

[0093] For example, the ratio of the width of at least one reverse leakage region in the first direction to the width of the overlapping region in the first direction can be greater than or equal to 0.5% and less than or equal to 100%. For instance, the ratio of the width of at least one reverse leakage region in the first direction to the width of the overlapping region in the first direction can be 0.5%, 1%, 10%, 20%, 30%, 50%, 50%, 80%, 90%, or 100%, etc. In this case, the width of the reverse leakage region in the first direction has a relatively large selectable range. When the back contact battery provided in this embodiment is installed in an environment with few obstructions such as bird droppings, leaves, or sand, the width of the reverse leakage region in the first direction can be set within a smaller range to reduce the recombination rate of carriers with opposite conductivity types in the reverse leakage region between the first doped semiconductor portion and the second doped semiconductor portion. This helps to reduce carrier recombination losses in the forward voltage region of the back contact battery, ensuring that the back contact battery has high operating efficiency. When the back contact battery provided in this embodiment is installed in an environment with many obstructions such as bird droppings, leaves, or sand, the width of the reverse leakage region in the first direction can be set within a larger range to improve the conductivity of the second doped semiconductor portion. This helps to reduce the reverse breakdown voltage of the back contact battery and reduces the risk of hot spots. Therefore, the width of the reverse leakage region in the first direction can be set according to different environmental requirements, improving the applicability of the back contact battery provided in this embodiment in different practical application scenarios.

[0094] Secondly, in practical applications, such as Figure 2 and Figure 3 As shown, the first edge 18 of the first transparent conductive layer 14 may only be located in the overlapping region 17. Specifically, a portion of the first edge 18 that coincides with the boundary of the overlapping region 17 and the second region 16 is also located in the overlapping region 17. In this case, as... Figure 2 and Figure 3 As shown, within the overlapping region 17, the reverse leakage region can be continuously distributed along the second direction; or, as... Figure 11 As shown, within the overlapping region 17, multiple reverse leakage regions are provided at intervals along the second direction. The aforementioned second direction intersects with the first direction.

[0095] Or, such as Figure 5As shown, a portion of the first edge line 18 may be located in the overlapping region 17, and another portion in the second region 16. In this case, when a step is formed between the second region 16 and the overlapping region 17, the first edge line 18 crosses the step along the first direction. In this case, when the first edge line 18 crosses the step formed by the second region 16 and the overlapping region 17 along the first direction, the transition line in the first edge line 18 is not parallel to the first direction. This can prevent the etching paste from filling the gap between the screen and the step at a vertical angle when the patterned first transparent conductive layer 14 is manufactured based on the screen, which would cause the etching paste to accumulate at the bottom of the step, resulting in poor formation quality of the first transparent conductive layer 14 at the bottom of the step. This is beneficial for the coverage of the first transparent conductive layer 14 at the step and helps to further reduce the risk of hot spots on the back contact battery.

[0096] Where a portion of the first edge line is located in the overlapping region and another portion is located in the second region, such as Figures 7 to 9 As shown, the recess 19 of the first edge 18 may extend into the second region 16. In this case, the second doped semiconductor portion 13 is not only disposed on the second region 16, but also extends to cover the first doped semiconductor portion 12 on the overlapping region 17. At this time, the second doped semiconductor portion 13 can be located not only on the side of the first doped semiconductor portion 12 on the overlapping region 17 away from the semiconductor substrate 11, but also on the sidewall of the first doped semiconductor portion 12 on the overlapping region 17. Furthermore, the first transparent conductive layer 14 is located on the second doped semiconductor portion 13, and at this time, the first transparent conductive layer 14 can contact the second doped semiconductor portion 13 disposed on the sidewall of the first doped semiconductor portion 12 on the overlapping region 17. In this case, when the recess 19 of the first edge 18 extends into the second region 16, the first transparent conductive layer 14 disposed in the second region 16 will not be electrically connected to the second doped semiconductor portion 13 at the recess 19. This ensures that the contact area between the second doped semiconductor portion 13 and the first transparent conductive layer 14 in the reverse leakage region can be effectively adjusted by adjusting the length of the disconnected portion and the continuous portion of the first transparent conductive layer 14 along the second direction, thereby achieving precise control of the reverse breakdown voltage and forward carrier recombination loss of the back contact battery. At the same time, in the actual application manufacturing process, it is not necessary to strictly require the screen printing precision and the placement precision of the screen on one side of the battery (i.e., alignment precision) in order to achieve the patterned first transparent conductive layer 14, which helps to reduce the manufacturing difficulty of the back contact battery.

[0097] Additionally, when part of the first edge line is located in the overlapping area and another part is located in the second area, such as Figures 7 to 10 As shown, in the overlapping region 17, multiple reverse leakage regions are distributed at intervals along the second direction, and the second direction intersects with the first direction.

[0098] It is worth noting that, such as Figures 7 to 11As shown, when multiple reverse leakage regions are spaced apart in the overlapping region 17 along the second direction, this provides an implementation method for the distribution of the first transparent conductive layer 14 disposed in the overlapping region 17 along the second direction. In this case, not only can the reverse breakdown voltage and forward carrier recombination loss of the back contact battery be controlled by adjusting the width of the first transparent conductive layer 14 disposed in the overlapping region 17 along the first direction, but also the reverse breakdown voltage and forward carrier recombination loss of the back contact battery can be controlled by adjusting the length of the continuous and discontinuous portions of the first transparent conductive layer 14 disposed in the overlapping region 17 along the second direction. This improves the applicability of the back contact battery provided in this embodiment of the invention in different application scenarios.

[0099] As for the second direction mentioned above, it can be any direction parallel to the first surface and different from the first direction. Preferably, the second direction is orthogonal to the first direction.

[0100] Regarding the size of the recessed portion of the first edge extending into the second region, it can be understood that in the transparent conductive layer, the portion disposed on the side of the second doped semiconductor portion away from the semiconductor substrate (needs to guide the carriers collected in the portion of the second doped semiconductor portion corresponding to the second region to the corresponding electrode when the back contact battery is in operation, and can reduce the contact barrier between the second doped semiconductor portion and the corresponding electrode, thereby reducing carrier transport loss). Based on this, the width of the portion of the recessed portion of the first edge extending into the second region along the first direction can be determined according to the requirements for carrier transport loss, leakage current control, and actual manufacturing process in the actual application scenario, and is not specifically limited here.

[0101] For example, along the first direction, the width of the recess of the first edge extending into the second region can be less than or equal to 100 μm. For instance, the width of the recess of the first edge extending into the second region can be 1 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 80 μm, or 100 μm, etc. In this case, the range of the recess of the first edge extending into the second region is relatively small, which helps to reduce the difficulty of selective etching while controlling the transport loss of carriers collected in the second doped semiconductor section within a certain range, ensuring that the back contact cell has a high photoelectric conversion efficiency.

[0102] In one possible implementation, such as Figure 12 and Figure 13 As shown, the back contact battery may further include a second transparent conductive layer 21 disposed on the first doped semiconductor portion 12. The first transparent conductive layer 14 and the second transparent conductive layer 21 are physically insulated. In this case, the presence of the second transparent conductive layer 21 can reduce the contact barrier between the first doped semiconductor portion 12 and the corresponding electrode, improve their contact performance, and further improve the conversion efficiency of the back contact battery.

[0103] Specifically, the spacing between the first transparent conductive layer and the second transparent conductive layer along the first direction can be determined based on the requirements for the carrier recombination rate between the first and second regions in the actual application scenario, and is not specifically limited here. Additionally, as... Figure 12 As shown, the second transparent conductive layer 21 may be disposed only on the first doped semiconductor portion 12 located in the first region 15. In this case, the second transparent conductive layer 21 may only cover a portion of the first doped semiconductor portion 12, or the second transparent conductive layer 21 may be close to the second edge 22 of the overlapping region 17, or it may coincide with the boundary between the first region 15 and the overlapping region 17.

[0104] Or, such as Figure 13 As shown, the second transparent conductive layer 21 can also extend from the first region 15 to cover a portion of the second doped semiconductor portion 13 located in the overlapping region 17. In this case, it can be ensured that the second transparent conductive layer 21 covers each portion of the first doped semiconductor portion 12 located in the first region 15, which is beneficial to improving carrier collection efficiency. In addition, it is not necessary to strictly control the manufacturing precision in order to align the edge of the second transparent conductive layer 21 with the boundary between the first region 15 and the overlapping region 17, reducing the manufacturing difficulty of the back contact battery. As for the width of the second transparent conductive layer 21 located in the overlapping region 17 along the first direction, it can be determined based on the width of the first transparent conductive layer 14 located in the overlapping region 17 along the first direction and the width of the overlapping region 17, and is not specifically limited here.

[0105] Among them, such as Figure 14 and Figure 15 As shown, the second side line 22 can be in the shape of a straight line, a diagonal line, a zigzag line, a trapezoidal broken line, or a wavy line. The application principle of the beneficial effect when there is no line segment parallel to the first direction in the second side line 22 can refer to the application principle of the beneficial effect of the first side line 18 being a wavy line, a zigzag line, or a trapezoidal broken line as described above, and will not be repeated here.

[0106] Regarding the material and thickness of the second transparent conductive layer, refer to the material and thickness of the first transparent conductive layer described above; they will not be repeated here. The material of the second transparent conductive layer can be the same as or different from that of the first transparent conductive layer. Specifically, when the materials of the second and first transparent conductive layers are the same, the second transparent conductive layer can be integrally formed with the first transparent conductive layer to simplify the manufacturing process of the back contact battery and help control the manufacturing cost of the back contact battery; of course, the second and first transparent conductive layers can also be formed separately in different operational steps.

[0107] In one example, such as Figure 13As shown, the aforementioned back-contact battery further includes a first electrode 23 and a second electrode 24. The first electrode 23 is disposed on the side of the first doped semiconductor portion 12 facing away from the semiconductor substrate 11 and is electrically connected to the first doped semiconductor portion 12. The second electrode 24 is disposed on the portion of the first transparent conductive layer 14 corresponding to the second region 16 and is electrically connected to the second doped semiconductor portion 13 through the first transparent conductive layer 14. The materials of the first electrode 23 and the second electrode 24 may include any conductive material such as silver, aluminum, copper, titanium, and nickel.

[0108] In one example, such as Figure 13 As shown, the aforementioned back contact battery also includes a surface passivation layer 27 disposed on one side of the second surface of the semiconductor substrate 11 to passivate the second surface of the semiconductor substrate 11 and reduce the carrier recombination rate on the second surface. The structure and material of the surface passivation layer 27 can be determined at least according to the requirements of the carrier recombination rate on the second surface in the actual application scenario and the actual manufacturing process, and are not specifically limited here.

[0109] For example, the surface passivation layer may include an intrinsic semiconductor passivation layer and a silicon nitride passivation layer sequentially stacked along the thickness direction of the semiconductor substrate on one side of the second surface. The material of the intrinsic semiconductor passivation layer includes amorphous silicon and / or microcrystalline silicon. In this case, the intrinsic semiconductor passivation layer included in the surface passivation layer can be formed simultaneously with the interface passivation layer included in the heterogeneous contact structure on one side of the first surface. The silicon nitride passivation layer included in the surface passivation layer can be formed simultaneously with the mask material for realizing the second passivation contact structure on one side of the first surface, without the need for additional operation steps to form the surface passivation layer, which is beneficial to improving the manufacturing efficiency of the back contact battery.

[0110] This utility model also provides the following three specific embodiments and a comparative example to illustrate the working performance of the back contact battery provided by this utility model:

[0111] Example 1

[0112] First, the silicon wafers are polished and cleaned. Specifically, the silicon wafers are immersed in a tank-type polishing and cleaning machine for polishing to remove the cutting damage layer. The polishing morphology of the first and second sides of the silicon wafer is controlled by adjusting the temperature, time, and solution concentration.

[0113] Next, the first deposition operation is performed. Specifically, a tunneling silicon oxide layer and an intrinsic polycrystalline silicon layer are deposited sequentially on one side of the first surface of the silicon wafer. Both the tunneling silicon oxide layer and the intrinsic polycrystalline silicon layer are achieved using a low-pressure chemical vapor deposition (LPCVD) furnace. Furthermore, the thickness of the tunneling silicon oxide layer is 1.4 nm, and the thickness of the intrinsic polycrystalline silicon layer is 120 nm.

[0114] Next, the phosphorus diffusion process is carried out. Specifically, intrinsic polysilicon is doped to form an N-type polysilicon layer through high-temperature diffusion, and a phosphosilicate glass layer is formed on the side of the N-type polysilicon layer facing away from the silicon wafer.

[0115] Next, the first wet etching operation is performed. Specifically, this step removes the aforementioned phosphosilicate glass layer using an HF solution. The HF solution concentration is 5%, and the etching time is 2 minutes.

[0116] Next, a second deposition operation is performed. A silicon nitride layer with a thickness of 80 nm and a refractive index of 2.0 is deposited on one side of the first surface of the silicon wafer using a plasma chemical vapor deposition (PCVD) system.

[0117] Next, the first laser etching operation is performed. Specifically, a laser etching process is used to remove the portion of the silicon nitride layer corresponding to the second region and the portion of the N-type doped polysilicon layer corresponding to the second region. The laser used can be a 532 picosecond laser.

[0118] Next, a second wet etching operation is performed. The purpose of this step is to create a pyramidal textured surface on the surface of the second region and the second face, while removing the silicon nitride layer deposited in the second deposition operation.

[0119] Next, a third deposition operation is performed. Specifically, a continuous intrinsic silicon layer and a P-type silicon layer are sequentially formed on one side of the silicon wafer using chemical vapor deposition (CVD). The intrinsic silicon layer has a thickness of 8 nm, and the P-type silicon layer has a thickness of 15 nm with a crystallinity of 5%. Simultaneously, in this step, an intrinsic silicon layer and an antireflection layer are deposited on the second side of the silicon wafer. The antireflection layer is a 75 nm thick silicon nitride layer.

[0120] Next, a second laser etching operation and a second wet etching operation are performed. Specifically, a laser etching process is used to remove the portion of the intrinsic silicon layer corresponding to the first region and the portion of the P-type silicon layer corresponding to the first region. A 532 picosecond laser is used. Then, using a chain-like device, the second side of the semi-finished product is placed facing upwards and protected with a water film. The first side of the semi-finished product is then brought into contact with an HF solution to remove the oxide layer formed during the doping of the P-type silicon layer and the silicon nitride layer deposited around the first side during the third deposition operation.

[0121] Next, a transparent conductive layer is deposited on one side of the first surface. This transparent conductive layer is made of an indium tin oxide layer with a thickness of 50 nm.

[0122] Next, the transparent conductive layer connecting the N-region and P-region is isolated, while the intrinsic silicon layer and P-type silicon layer above the overlapping region are also isolated to achieve complete structural insulation between the two polarity regions. Isolation is achieved using an etching paste. The etching pattern ensures that at least a portion of the transparent conductive layer overlaps across the P-region and the overlapping region, and that the transparent conductive layers on the N-region and P-region are physically insulated. The structure of the transparent conductive layer overlapping across the P-region and the overlapping region is uniformly distributed throughout the entire cell area. The ratio of the width of the portion of the transparent conductive layer extending into the overlapping region to the width of the overlapping region is 5%, and the first edge of the transparent conductive layer extending from the P-region to the overlapping region is... Figure 8 The arc shown.

[0123] Next, a metallization process is performed. Specifically, metallic silver electrodes are fabricated above the two transparent conductive layers to enable carrier collection and interconnection of the electrodes throughout the battery.

[0124] Example 2

[0125] In the back contact battery provided in Example 2, the first edge of the transparent conductive layer extending from the P region to the overlapping region is... Figure 7 Apart from the serrated lines shown, the rest of the configuration is the same as the back contact battery provided in Example 1.

[0126] Example 3

[0127] In the back contact battery provided in Example 3, the first edge of the transparent conductive layer extending from the P region to the overlapping region is... Figure 9 Apart from the trapezoidal broken line shown, the rest of the configuration is the same as the back contact battery provided in Example 1.

[0128] Comparative Example

[0129] In the comparative example of the back contact battery, the first edge of the transparent conductive layer extending from the P-region to the overlapping region is... Figure 16 Apart from the rectangular broken line shown, the rest of the configuration is the same as the back contact battery provided in Example 1.

[0130] Table 1 shows the test parameters for the back contact batteries provided in Examples 1 to 3 and the comparative examples.

[0131] project efficiency(%) Reverse bias voltage (V) Screen printing plate lifespan (10,000 cycles) Comparative Example 26.7 -5 5 Example 1 26.82 -5 8 Example 2 26.83 -5 8.5 Example 3 26.81 -5 9

[0132] It should be noted that the data in Table 1 were obtained by selecting 10,000 back-contact batteries as samples from each of the back-contact battery product lines corresponding to Examples 1-3 and the comparative examples. Efficiency tests were conducted on 10,000 samples from each example, and the average value was calculated to obtain the efficiency data in the table. Specifically, reverse breakdown voltage tests were performed on 10% of the 10,000 samples from each example, and the average value was calculated to obtain the reverse breakdown voltage data in the table. Under the above conditions, it can be seen from the data in Table 1 that when the transition line between the unevenness and concavity in the first edge of the transparent conductive layer extending from the P-region to the overlapping region is not parallel to the first direction, the lifespan of the screen used to manufacture the transparent conductive layer is longer. Furthermore, this is beneficial for improving the yield and conversion efficiency of the back-contact battery.

[0133] Secondly, embodiments of the present invention provide a photovoltaic module. This photovoltaic module includes the back-contact battery provided in the first aspect and its various implementations described above.

[0134] The beneficial effects of the second aspect and its various implementations in the embodiments of this utility model can be referred to the analysis of the beneficial effects of the first aspect and its various implementations, and will not be repeated here.

[0135] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model 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 this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A back-contact battery, characterized in that, include: A semiconductor substrate, a first doped semiconductor portion, a second doped semiconductor portion, and a first transparent conductive layer; the second doped semiconductor portion and the first doped semiconductor portion have opposite conductivity types; The semiconductor substrate includes a first surface and a second surface opposite to each other; the first surface includes a plurality of first regions and a plurality of second regions, and an overlapping region located between the first regions and the second regions; the first regions, the overlapping region, and the second regions are arranged along a first direction; The first doped semiconductor portion is disposed in the first region and the overlapping region; The second doped semiconductor portion is disposed on the second region and extends to cover the first doped semiconductor portion located in the overlapping region; The first transparent conductive layer is disposed on the second doped semiconductor portion; Among them, a portion of the overlapping region is a reverse leakage region; In the reverse leakage region, a first transparent conductive layer extending from the second region is provided, and the first transparent conductive layer is electrically connected to the first doped semiconductor portion through the second doped semiconductor portion. The edge of the first transparent conductive layer near the first region is called the first edge. The first edge has a periodically repeating alternating convex and concave structure, and the transition line between the convex and concave parts in the alternating convex and concave structure is not parallel to the first direction.

2. The back contact battery according to claim 1, characterized in that, The transition line is a curve or a sloping line; Alternatively, the first edge line may be a wavy line, a sawtooth line, or a trapezoidal broken line.

3. The back contact battery according to claim 2, characterized in that, When the transition line is a diagonal line, the angle between the diagonal line and the first direction is greater than or equal to 5° and less than or equal to 85°.

4. The back contact battery according to claim 1, characterized in that, Along the length extension direction of the first edge line, within a unit length of 1 cm, the number of convex and concave structures is greater than or equal to 1 and less than or equal to 200.

5. The back contact battery according to claim 1, characterized in that, In the overlapping region, a plurality of the reverse leakage regions are distributed at intervals along the second direction, and the second direction intersects the first direction.

6. The back contact battery according to claim 5, characterized in that, The recessed portion of the first edge extends into the second region.

7. The back contact battery according to claim 6, characterized in that, The second region of the semiconductor substrate is recessed into the semiconductor substrate relative to the overlapping region; a step is formed at the intersection of the second region and the overlapping region. The first edge line crosses the step along the first direction.

8. The back contact battery according to claim 1, characterized in that, The ratio of the width of at least one of the reverse leakage regions in the first direction to the width of the overlapping region in the first direction is greater than or equal to 0.5% and less than or equal to 100%.

9. The back contact battery according to claim 1, characterized in that, The back contact battery further includes a second transparent conductive layer disposed on the first doped semiconductor portion; the first transparent conductive layer and the second transparent conductive layer are physically insulated from each other.

10. The back contact battery according to claim 9, characterized in that, The second transparent conductive layer extends from the first region and covers a portion of the second doped semiconductor portion located in the overlapping region; And / or, the edge of the second transparent conductive layer on the side closest to the second region is the second edge, which is a straight line, a diagonal line, a zigzag line, a trapezoidal zigzag line, or a wavy line.

11. The back contact battery according to claim 1, characterized in that, The back contact battery further includes a first interface passivation layer located between the first doped semiconductor portion and the semiconductor substrate; The back contact battery further includes a second interface passivation layer, which is located at least between the second doped semiconductor portion and the semiconductor substrate. The first interface passivation layer and the first doped semiconductor portion constitute a first passivation contact structure, and the second interface passivation layer and the second doped semiconductor portion constitute a second passivation contact structure. Wherein, the first passivation contact structure is a tunneling passivation contact structure; the second passivation contact structure is a heterogeneous contact structure.

12. A photovoltaic module, characterized in that, Including the back contact battery as described in any one of claims 1 to 11.

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