Back contact solar cell, method of manufacturing the same, and photovoltaic module

Abstract

The application provides a back contact solar cell, a preparation method thereof and a photovoltaic module, and relates to the technical field of photovoltaics. The back contact solar cell comprises a silicon substrate; a first surface of the silicon substrate comprises a first conductive region, a second conductive region and a laminated region between the first conductive region and the second conductive region; a first transport layer is located on the first conductive region and the laminated region; a second transport layer is located on the second conductive region and the laminated region, and in the laminated region, the second transport layer is located on a side of the first transport layer away from the silicon substrate; in the laminated region: a side of the first transport layer close to the second conductive region has a first concave-convex morphology, and a side of the second transport layer close to the first conductive region has a second concave-convex morphology; and the first concave-convex morphology is different from the second concave-convex morphology. The passivation effect of the application at the junction of the first transport layer close to the second conductive region is good, and the power generation efficiency of the back contact solar cell is improved.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to a back-contact solar cell, its preparation method, and a photovoltaic module. Background Technology

[0002] Back-contact solar cells, due to their grid-free structure on the light-facing side, can make full use of sunlight, resulting in higher efficiency. Furthermore, the grid-free structure on the light-facing side makes the module appearance more aesthetically pleasing, thus offering broad application prospects.

[0003] In back-contact solar cells, both types of conductive transport layers are located on the same side of the silicon substrate. Therefore, a stacked region is usually set between the two conductive regions, and an opening is set in the stacked region to reduce the risk of leakage.

[0004] However, the passivation effect of the stacked region in the back contact solar cell is not good, which affects the power generation efficiency of the cell. Summary of the Invention

[0005] This invention provides a back-contact solar cell, its fabrication method, and a photovoltaic module, aiming to solve the problem of poor passivation effect in the stacked region of existing back-contact solar cells.

[0006] A first aspect of the present invention provides a back-contact solar cell, comprising: a silicon substrate; the silicon substrate comprising: a first surface and a second surface opposite to each other; the first surface comprising: a first conductive region, a second conductive region, and a stacked region located between the first conductive region and the second conductive region; the first conductive region, the stacked region, and the second conductive region are sequentially distributed in a first direction;

[0007] A first transmission layer is located on the first conductive region and the stacked region;

[0008] A second transport layer is located on the second conductive region and the stacked region, and at least a portion of the second transport layer is located on the side of the first transport layer away from the silicon substrate in the stacked region; the first transport layer and the second transport layer have different conductivity types.

[0009] In the stacked region: the first transport layer has a first uneven morphology extending along a second direction on the side near the second conductive region, and the second transport layer has a second uneven morphology extending along the second direction on the side near the first conductive region. The first uneven morphology is different from the second uneven morphology. The second direction intersects with the first direction and is perpendicular to the direction of the thickness of the silicon substrate.

[0010] In this application, the second transport layer is superimposed on the first transport layer, meaning that the second transport layer is fabricated after the first transport layer is completed. In the stacked region, the first and second uneven morphologies differ. Because of these differences, the films grown on these two different morphologies exhibit randomness, which allows for better coverage of the underlying layer structure, improving the passivation effect in the stacked region and enhancing the power generation efficiency of the solar cell.

[0011] Optionally, the first uneven morphology is different from the second uneven morphology, including: the unevenness amplitude of the first uneven morphology is different from the unevenness amplitude of the second uneven morphology, and / or the unevenness frequency of the first uneven morphology is different from the unevenness frequency of the second uneven morphology.

[0012] The difference between the first and second convex morphologies can be further refined into the following: the convex amplitude of the first convex morphology is different from that of the second convex morphology, and / or the convex frequency of the first convex morphology is different from that of the second convex morphology. By using the convex amplitude and / or convex frequency, it is easy to achieve different first and second convex morphologies from a manufacturing perspective.

[0013] Optionally, the unevenness of the first unevenness morphology differs from that of the second unevenness morphology, including:

[0014] In the first direction, the concavity and convexity of the first concavity and convexity is smaller than that of the second concavity and convexity.

[0015] The convexity frequency of the first convexity morphology is different from that of the second convexity morphology, including:

[0016] In the second direction, the convexity frequency of the first convexity is greater than the convexity frequency of the second convexity.

[0017] In this application, the second transport layer is overlaid on the first transport layer, meaning it is fabricated after the first transport layer is completed. Firstly, the first unevenness of the first transport layer near the second conductive region has a smaller amplitude and / or a larger frequency, making it relatively flat and / or more regular and consistent. This results in a higher quality second transport layer film, leading to better passivation at the boundary between the first transport layer and the second conductive region, or at the boundary between the second conductive region and the stacked region. This improves the passivation effect at the boundary of the first transport layer near the second conductive region in the back-contact solar cell, thereby increasing the power generation efficiency of the back-contact solar cell. Secondly, the first transport layer beneath the second transport layer near the first conductive region provides good passivation performance. The larger amplitude and / or smaller frequency of the second unevenness of the second unevenness of the second transport layer near the first conductive region results in a larger specific surface area and / or greater irregularity, which further enhances the light-trapping effect at the boundary between the first conductive region and the stacked region, improving the light utilization rate of the silicon substrate. Similarly, it improves the power generation efficiency of back-contact solar cells; thirdly, the shape of the first uneven morphology on the side of the first transport layer near the second conductive region is relatively regular with varying heights. When a passivation layer, a second transport layer, or a transparent conductive layer is deposited on the side of the first transport layer near the second conductive region, the quality of these films is better, more uniform and neat. In particular, when using vapor deposition such as CVD (chemical vapor deposition), the regular shape of the first uneven morphology has a regular influence on the atmosphere in vapor deposition, making the distribution of the atmosphere in the space of this region more uniform. It will not disrupt the atmosphere environment due to irregular shading, thus enabling better production and deposition of the above-mentioned films in this region; fourthly, the first uneven morphology on the side of the first transport layer near the second conductive region and the second uneven morphology on the side of the second transport layer near the first conductive region both have regular shapes with varying heights. The regular shapes located at the edges can also provide a larger error margin for subsequent patterning accuracy, improving the process yield.

[0018] Optionally, at the boundary between the stacked region and the second conductive region, the second transmission layer covers the side of the first transmission layer.

[0019] Optionally, the first uneven topography includes: a first sub-uneven topography and a second sub-uneven topography; along the first direction, a second conductive region includes opposing first ends and second ends;

[0020] The first sub-concave-convex shape is adjacent to the first end, and the second sub-concave-convex shape is adjacent to the second end;

[0021] The first sub-concave-convex morphology and the second sub-concave-convex morphology have different concave-convex amplitudes.

[0022] Optionally, the back-contact solar cell further includes: a transparent conductive layer, wherein the transparent conductive layer is disposed at least on the first transmission layer of the first conductive region and on the second transmission layer of the second conductive region;

[0023] The transparent conductive layer has a break opening, which is provided at least in the stacked region.

[0024] Optionally, the back-contact solar cell further includes: a transparent conductive layer disposed on a first transmission layer in the first conductive region, a second transmission layer in the second conductive region, and a second transmission layer in the stacked region; wherein, at a local location in the stacked region, the transparent conductive layer and the second transmission layer have a disconnection opening;

[0025] Along the first direction, the second transmission layer includes opposing third and fourth ends at one of the openings;

[0026] The side surface of the third end and the side surface of the fourth end both have a third concave-convex shape, which is different from the first concave-convex shape and the second concave-convex shape.

[0027] Optionally, the third convex-concave morphology differs from both the first and second convex-concave morphologies, including:

[0028] The concavity and convexity of the third concavity and convexity are different from the concavity and convexity of the first concavity and convexity and the concavity and convexity of the second concavity and convexity.

[0029] And / or, the convexity frequency of the third convexity is different from the convexity frequency of the first convexity and the convexity frequency of the second convexity.

[0030] Optionally, the first uneven morphology is formed by a first laser, and the second uneven morphology is formed by a second laser;

[0031] The overlap rate of the first laser beam is greater than that of the second laser beam.

[0032] Optionally, the power density of the first laser is greater than or equal to the power density of the second laser.

[0033] Optionally, the spot size of the first laser is larger than the spot size of the second laser.

[0034] Optionally, the first transport layer has a third surface and a fourth surface opposite to each other, the third surface being the surface of the first transport layer away from the silicon substrate, and the fourth surface being the surface of the first transport layer close to the silicon substrate;

[0035] The second transport layer has a fifth surface and a sixth surface opposite to each other, the fifth surface being the surface of the second transport layer away from the silicon substrate, and the sixth surface being the surface of the second transport layer close to the silicon substrate;

[0036] In the thickness direction of the silicon substrate, the distance from the third surface of the first transport layer to the silicon substrate is greater than the distance from the fifth surface of the second transport layer to the fourth surface of the first transport layer.

[0037] Optionally, in the first direction, the width of the second conductive region is greater than the width of the first conductive region.

[0038] Optionally, in the first direction, the width of the first conductive region is greater than or equal to the spot size of the second laser.

[0039] Optionally, the first uneven morphology is formed by a first laser, the second uneven morphology is formed by a second laser, and the third uneven morphology is formed by a third laser;

[0040] The beam overlap rate of the third laser is different from that of the first laser, and the beam overlap rate of the third laser is different from that of the second laser.

[0041] A second aspect of the present invention provides a method for fabricating a back-contact solar cell, comprising:

[0042] A silicon substrate is provided; the silicon substrate includes: a first surface and a second surface opposite to each other; the first surface includes: a first conductive region, a second conductive region, and a stacked region located between the first conductive region and the second conductive region; the first conductive region, the stacked region, and the second conductive region are distributed in a first direction;

[0043] A first transport layer, consisting of an entire layer, is formed on the first surface;

[0044] The portion of the first transmission layer located on the second conductive region is processed using a first laser to expose the second conductive region.

[0045] A second transport layer is formed on the second conductive region and the first transport layer; the first transport layer and the second transport layer have different conductivity types;

[0046] A second laser is used to remove the portion of the second transmission layer located on the first conductive region, exposing the first transmission layer.

[0047] In the stacked region, at least a portion of the second transport layer is located on the side of the first transport layer facing away from the silicon substrate; in the stacked region: the side of the first transport layer near the second conductive region has a first uneven morphology extending along a second direction, and the side of the second transport layer near the first conductive region has a second uneven morphology extending along the second direction, the first uneven morphology being different from the second uneven morphology; the second direction intersects the first direction and is perpendicular to the direction of the thickness of the silicon substrate.

[0048] Optionally, the power density of the first laser is greater than or equal to the power density of the second laser.

[0049] Optionally, the method for fabricating the back-contact solar cell further includes:

[0050] A full-length transparent conductive layer is formed on the side of the first and second transport layers opposite to the silicon substrate;

[0051] A third laser is used to form openings in local locations of the transparent conductive layer and the second transmission layer in the stacked region.

[0052] A third aspect of the present invention provides a photovoltaic module comprising: a plurality of any of the aforementioned back-contact solar cells.

[0053] The aforementioned back-contact solar cells and their preparation methods have the same or similar beneficial effects as photovoltaic modules, and will not be repeated here to avoid repetition. Attached Figure Description

[0054] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 A partial structural schematic diagram of a back-contact solar cell according to an embodiment of the present invention is shown;

[0056] Figure 2 A partial structural schematic diagram of the first concave-convex morphology in an embodiment of the present invention is shown;

[0057] Figure 3 A partial structural schematic diagram of the second concave-convex morphology in an embodiment of the present invention is shown;

[0058] Figure 4 A partial structural schematic diagram of another back-contact solar cell according to an embodiment of the present invention is shown;

[0059] Figures 5 to 11 A schematic diagram of the process steps of a back-contact solar cell according to an embodiment of the present invention is shown.

[0060] Explanation of the attached drawing numbers:

[0061] 1-Silicon substrate, 2-Tunneling oxide layer, 3-N-type doped polycrystalline silicon layer, 4-Dielectric layer, 5-Break position, 6-Intrinsic amorphous silicon layer, 7-P-type doped amorphous silicon layer, 8-Front-side passivation layer, 9-Front-side anti-reflection layer, 10-Notch, 11-Transparent conductive layer, 12-Opening, 13-Electrode. Detailed Implementation

[0062] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0063] This invention provides a back-contact solar cell, as shown in the reference. Figure 1 The back-contact solar cell includes a silicon substrate 1, a first transport layer, and a second surface. The silicon substrate 1 includes opposing first and second surfaces. The first surface serves as its back-light-receiving surface, and the second surface is its light-facing surface. During normal operation of the back-contact solar cell, the surface of the silicon substrate 1 that primarily absorbs light is the light-facing surface. Figures 1 to 11 The upper surface of the silicon substrate 1 is its first surface (see reference). Figure 5 As shown in Figure B), the lower surface is its second surface (refer to Figure B). Figure 5 (As shown in Figure F). The first surface includes: a first conductive region, a second conductive region, and a stacked region located between the first conductive region and the second conductive region. (Refer to...) Figure 1 In the first surface, the region to the left of the dashed line L1 is the first conductive region, the region between dashed lines L1 and L2 is the stacked region, and the region to the right of dashed line L2 is the second conductive region. The direction in which the first conductive region, the stacked region, and the second conductive region are distributed sequentially on the first surface is the first direction M.

[0064] The first transport layer is located on the first conductive region and the stacked region; the second transport layer is located on the second conductive region and the stacked region, that is, the first transport layer is located on the region to the left of the dashed line L2 on the first surface. The second transport layer is located on the region to the right of the dashed line L1 on the first surface, and within the stacked region from dashed line L1 to dashed line L2, at least a portion of the second transport layer is farther away from the silicon substrate than the first transport layer. In other words, during the formation of the back-contact solar cell, the first transport layer is formed first, followed by the second transport layer. The first and second transport layers have different conductivity types; one is an N-type transport layer, and the other is a P-type transport layer. The specific materials used for the N-type and P-type transport layers are not limited.

[0065] For example, the first transport layer can be an N-type transport layer, and the second transport layer can be a P-type transport layer. The first transport layer may include a tunneling oxide layer 2 and an N-type doped polycrystalline silicon layer 3. The second transport layer may include an intrinsic amorphous silicon layer 6 and a P-type doped amorphous silicon layer 7.

[0066] It should be noted that the dashed lines L1 to L2 mentioned in the full text and figures of this application are only for distinguishing different areas and do not exist in actual back-contact solar cells.

[0067] In the stacked region: refer to Figure 2 The side of the first transport layer near the second conductive region has a first uneven morphology extending along the second direction Q, which is... Figure 1 In the diagram, the first transmission layer has a first uneven morphology extending along the second direction Q on the side at the location of the dashed line L2, as shown in the reference diagram. Figure 3 The second transport layer has a second uneven morphology extending along the second direction Q on its side near the first conductive region. Figure 1 In the diagram, the second transport layer has a second uneven morphology extending along the second direction Q on the side surface at the location of the dashed line L1. The first uneven morphology is different from the second uneven morphology. The second direction Q intersects the first direction M and is perpendicular to the thickness direction N of the silicon substrate 1. In this application, the second transport layer is overlaid on the first transport layer, meaning that the second transport layer is fabricated after the first transport layer is fabricated. In the stacked region, the first uneven morphology and the second uneven morphology are different. Because the two morphologies are different, the film layers grown on the two different morphologies have randomness, which can better cover the underlying layer structure, improve the passivation effect of the stacked region, and improve the power generation efficiency of the solar cell.

[0068] It should be noted that the difference between the first and second concave-convex morphologies is that the various parameters related to the shape of the first concave-convex morphology are not equal to those related to the shape of the second concave-convex morphology.

[0069] Optional, refer to Figure 2 and Figure 3 The aforementioned difference between the first and second concave-convex topography includes: the concave-convex amplitude R1 of the first concave-convex topography is different from the concave-convex amplitude R2 of the second concave-convex topography; and / or, the concave-convex frequency of the first concave-convex topography is different from the concave-convex frequency of the second concave-convex topography. Here, the concave-convex amplitude refers to: [referring to...] Figure 2 and Figure 3 The first convex-concave topography includes peaks and troughs in the first direction M. The convex-concave amplitude R1 of the first convex-concave topography refers to the distance between a peak and a trough in the first direction M, or it can be the average of the distances between multiple peaks and multiple troughs in the first convex-concave topography in the first direction M. The determination of the convex-concave amplitude R2 of the second convex-concave topography is similar. The convex-concave frequency here refers to the number of concave points (troughs) and / or convex points (peaks) in the first convex-concave topography and the number of concave points and / or convex points in the second convex-concave topography within the same size along the second direction Q; or the number of times concave points and / or convex points are counted in the first convex-concave topography and the number of times concave points or convex points are counted in the second convex-concave topography per unit size along the second direction Q. The more times the count, the greater the convex-concave frequency. It should be noted that the determination method for the convex-concave frequency of the first convex-concave topography is the same as that for the second convex-concave topography. The difference between the first and second convex morphologies can be further refined into the following: the convex amplitude R1 of the first convex morphology is different from the convex amplitude R2 of the second convex morphology, and / or the convex frequency of the first convex morphology is different from the convex frequency of the second convex morphology. By using the convex amplitude and / or convex frequency, it is easy to achieve different first and second convex morphologies from a manufacturing perspective.

[0070] Optional, refer to Figure 2 and Figure 3 The aforementioned unevenness amplitude R1 of the first unevenness morphology differs from that of the second unevenness morphology, including: in the first direction M, the unevenness amplitude R1 of the first unevenness morphology is smaller than that of the second unevenness morphology; the aforementioned unevenness frequency of the first unevenness morphology differs from that of the second unevenness morphology, including: in the aforementioned second direction Q, the unevenness frequency of the first unevenness morphology is greater than that of the second unevenness morphology. For example, Figure 2 and Figure 3 In the first concave-convex morphology, along the second direction Q, the distance between adjacent valleys or adjacent peaks is d2, and along the second direction Q, the distance between adjacent valleys or adjacent peaks in the second concave-convex morphology is d3. Since d2 < d3, along the second direction Q, within the same size, the number of valleys or peaks in the first concave-convex morphology is greater than the number of valleys (concave points) or peaks (convex points) in the second concave-convex morphology. Consequently, the concave-convex frequency of the first concave-convex morphology is greater, and the distribution of the first concave-convex morphology is more regular or more systematic.

[0071] Specifically, the second transport layer is superimposed on the first transport layer, meaning it is fabricated after the first transport layer is completed. Firstly, the first unevenness morphology of the side of the first transport layer near the second conductive region has a smaller unevenness amplitude R1 and / or a larger unevenness frequency. This makes the side of the first transport layer near the second conductive region relatively flat and / or more regular and consistent, resulting in a better quality second transport layer film. Consequently, the passivation effect at the boundary between the first transport layer and the second conductive region, or at the boundary between the second conductive region and the stacked region, is better, improving the passivation effect at the boundary of the first transport layer near the second conductive region in the back-contact solar cell and thus increasing the power generation efficiency of the back-contact solar cell. Secondly, the first transport layer under the side of the second transport layer near the first conductive region can provide good passivation performance. The larger unevenness amplitude and / or smaller unevenness frequency of the second unevenness morphology on the side of the second transport layer near the first conductive region results in a larger specific surface area and / or greater irregularity, which is beneficial for further increasing the light-trapping effect at the boundary region between the first conductive region and the stacked region, improving the utilization of light by the silicon substrate. The first uneven morphology of the first transport layer near the second conductive region has a relatively regular shape with varying heights. When a passivation layer, a second transport layer, or a transparent conductive layer is deposited on the side of the first transport layer near the second conductive region, the quality of these films is better, more uniform and neat. In particular, when using vapor deposition such as CVD (chemical vapor deposition), the regular shape of the first uneven morphology has a regular influence on the atmosphere in vapor deposition, making the distribution of the atmosphere in the space of the region more uniform. It will not be disrupted by irregular shading, thus making the region better for the deposition of the above-mentioned films. Fourth, the first uneven morphology of the side of the first transport layer near the second conductive region and the second uneven morphology of the side of the second transport layer near the first conductive region both have regular shapes with varying heights. The regular shapes located at the edges can also provide a larger error margin for subsequent patterning accuracy, improving the process yield.

[0072] Optionally, the first uneven morphology is formed by a first laser, and the second uneven morphology is formed by a second laser. The overlap rate of the first laser spot is greater than that of the second laser spot. As a result, the unevenness amplitude R1 of the first uneven morphology is less than that of the second uneven morphology, and / or the unevenness frequency of the first uneven morphology is greater than that of the second uneven morphology.

[0073] Optional, refer to Figure 1 and Figure 4In the boundary region between the stacked region and the second conductive region, the second transport layer covers the side of the first transport layer. The second transport layer covers the side of the first transport layer in this boundary region, that is, in... Figure 1 In the diagram, at the location of the dashed line L2, the second transport layer covers the side of the first transport layer. The second transport layer provides comprehensive coverage of this boundary region, resulting in better passivation at the boundary between the first transport layer and the second conductive region, or at the boundary between the second conductive region and the stacked region. This improves the passivation effect at the boundary between the first transport layer and the second conductive region in the back-contact solar cell, thereby enhancing the power generation efficiency of the back-contact solar cell.

[0074] Optional, refer to Figure 1 and Figure 4 Along the first direction M, the width d1 of the stacked region is 20μm to 400μm. If d1 is too small, the electrical isolation effect is poor and may introduce short circuit risk. If d1 is too large, more carrier collection dead zone is introduced. If d1 is within the above range, not only is the electrical isolation effect good, but the introduced carrier collection dead zone is also small.

[0075] For example, along the first direction M, the width d1 of the stacked region can be 20μm, 40μm, 50μm, 100μm, 80μm, 120μm, 150μm, 180μm, 200μm, 250μm, 280μm, 300μm, 350μm, 330μm, or 400μm.

[0076] Optional, refer to Figure 4 The first uneven topography includes: a first sub-uneven topography and a second sub-uneven topography; along the first direction M, a second conductive region includes a first end and a second end opposite to each other; Figure 4 In this structure, the portion between L2 and L2 on the first surface constitutes a second conductive region. The positions of the two L2s are the first and second ends of the second conductive region, respectively. The first end is either of the two L2s, and the second end is the other of the two L2s. The first sub-undulation is adjacent to the first end, and the second sub-undulation is adjacent to the second end. The unevenness of the first and second sub-undulations differs, meaning their unevenness amplitudes R1 are different. However, both R1s are smaller than R2. For a single second conductive region, the two R1s at the two ends can be different, allowing for a larger processing window. Furthermore, since both R1s are still relatively small, the two sides of the first transport layer near the second conductive region are relatively flat, resulting in a better film quality for the second transport layer formed on it. Consequently, the passivation effect at the boundary between the first transport layer and the second conductive region, or at the boundary between the second conductive region and the stacked region, is better. This improves the passivation effect at the boundary between the first transport layer and the second conductive region in the back contact solar cell, thereby increasing the power generation efficiency of the back contact solar cell.

[0077] It should be noted that, for a second conductive region, the difference between the two R1 values ​​at both ends is not specifically limited, even if they are not identical. For a second conductive region, the two R1 values ​​at both ends can also be the same.

[0078] Optionally, the back-contact solar cell further includes: a transparent conductive layer, which is disposed at least on the first transport layer of the first conductive region and the second transport layer of the second conductive region; wherein the transparent conductive layer has a break opening, which is mainly used to provide good electrical isolation and prevent short circuits, and the break opening is disposed at least on the stacked region. Below the break opening, the second transport layer and the first transport layer can be continuously distributed. The break opening can be formed by etching paste. The relative relationship between the size of the break opening and the size of the stacked region is not specifically limited; they can be equal, or the break opening can be larger than the stacked region, or the break opening can be smaller than the stacked region.

[0079] Optional, refer to Figure 1 The back-contact solar cell further includes: a transparent conductive layer 11 located on a first transport layer in a first conductive region, a second transport layer in a second conductive region, and a second transport layer in a stacked region; the transparent conductive layer 11 and the second transport layer have a disconnection opening 12 at a local location in the stacked region, which can provide good electrical isolation and prevent short circuits. Along the first direction M, the second transport layer includes a third end and a fourth end at one opening; the sides of the third end and the sides of the fourth end both have a third unevenness extending along the second direction Q; along the first direction M, the difference between the unevenness amplitude of the third unevenness amplitude of the side of the third end and the side of the fourth end is less than or equal to 5% of the unevenness amplitude of the third unevenness amplitude of the side of either the third end or the fourth end. Here, the third end is any one end of the second transport layer at one opening along the first direction M, and the fourth end is the other end of the second transport layer at one opening along the first direction M. The difference between the concavity / convexity amplitude of the third concavity / convexity morphology on the third end side and the third concavity / convexity morphology on the fourth end side is less than or equal to 5% of the concavity / convexity amplitude of the third concavity / convexity morphology on either the third end side or the fourth end side. This indicates that the difference between the concavity / convexity amplitude of the third concavity / convexity morphology on the third end side and the third concavity / convexity morphology on the fourth end side is very small and almost equal. This suggests that the patterning process parameters on the third end and the fourth end side are roughly the same or identical, and the process parameters can be shared during their formation, making the process simple.

[0080] For example, the difference between the concavity / convexity amplitude of the third concavity / convexity morphology on the side of the third end and the concavity / convexity amplitude of the third concavity / convexity morphology on the side of the fourth end can be 5%, 4%, 4.5%, 3%, 3.5%, 2%, 2.5%, 1.5%, 0.5%, 0.3%, or 0% of the concavity / convexity amplitude of the third concavity / convexity morphology on the side of either the side of the third end or the side of the fourth end.

[0081] Optionally, the third uneven morphology differs from the aforementioned first and second uneven morphologies in that various parameters related to the shape of the third uneven morphology are not equal to those related to the shape of the first uneven morphology. Furthermore, the various parameters related to the shape of the third uneven morphology are also not equal to those related to the shape of the second uneven morphology. In other words, the first, second, and third uneven morphologies are each matched to their respective requirements, which can further improve the performance of the back-contact solar cell. It should be noted that the formation processes of the first, second, and third uneven morphologies may not be in the same step, or the formation process parameters for the three may be different.

[0082] Optionally, the aforementioned third concave-convex morphology differs from the first and second concave-convex morphologies in the following ways: the concave-convex amplitude of the third concave-convex morphology differs from that of the first concave-convex morphology, and the concave-convex amplitude of the third concave-convex morphology also differs from that of the second concave-convex morphology; and / or, the concave-convex frequency of the third concave-convex morphology differs from that of the first concave-convex morphology, and the concave-convex frequency of the third concave-convex morphology also differs from that of the second concave-convex morphology. Refining the difference in concave-convex morphology to differences in concave-convex amplitude and / or concave-convex frequency facilitates process control and makes it easier to form first, second, and third concave-convex morphologies with different morphologies. The definitions of concave-convex amplitude and concave-convex frequency here can refer to the corresponding definitions mentioned above; to avoid repetition, they will not be repeated here.

[0083] Optionally, the overlap rate of the third laser spot forming the opening 12 is different from the overlap rate of the first laser spot, and the overlap rate of the third laser spot is different from the overlap rate of the second laser spot. Therefore, the third concave-convex morphology formed on the side of the opposite third and fourth ends of the second transmission layer at an opening, extending along the second direction Q, is different from the shape of the first concave-convex morphology, and the shape of the third concave-convex morphology is also different from the shape of the second concave-convex morphology.

[0084] Optionally, the size of the first laser spot is larger than the size of the second laser spot. Here, the size of the second laser spot can be its length or its width. That is, the length and width of the second laser spot are both smaller than the length and width of the first laser spot. As a result, the concavity amplitude R1 of the first concavity-convex morphology is smaller than the concavity amplitude R2 of the second concavity-convex morphology, and / or, the concavity frequency of the first concavity-convex morphology is greater than the concavity frequency of the second concavity-convex morphology.

[0085] Optional, refer to Figure 1 The first transport layer has a third surface and a fourth surface opposite to each other. The third surface is the surface of the first transport layer away from the silicon substrate 1, and the fourth surface is the surface of the first transport layer close to the silicon substrate 1. The second transport layer has a fifth surface and a sixth surface opposite to each other. The fifth surface is the surface of the second transport layer away from the silicon substrate 1, and the sixth surface is the surface of the second transport layer close to the silicon substrate 1. In the thickness direction N of the silicon substrate 1, the distance d4 from the third surface of the first transport layer to the silicon substrate 1 is greater than the distance d5 from the fifth surface of the second transport layer to the fourth surface of the first transport layer, i.e., d4 > d5. Specifically, in the stacked region near the second conductive region, this area has photoelectric conversion and / or hot spot prevention functions. In the stacked region near the first conductive region, this area does not actually have photoelectric conversion and / or hot spot prevention functions. Therefore, especially in the stacked region near the second conductive region, the film quality in this area needs special consideration. The distance d4 from the third surface of the first transport layer to the silicon substrate 1 surface of the second conductive region is longer than the distance d5 from the fifth surface of the second transport layer to the fourth surface of the first transport layer. This improves the film quality in the stacked region near the second conductive region, and enhances the passivation and / or hot spot prevention effects to ensure the power generation efficiency of the solar cell. When the unevenness of the first transport layer's side surface near the second conductive region in the stacked region is small in amplitude and / or large in frequency, the passivation layer, second transport layer, or transparent conductive layer is deposited on this side surface. This results in better quality, more uniformity, and neatness of the deposited films. Especially when using vapor deposition such as CVD (chemical vapor deposition), the first unevenness has minimal impact on the atmosphere during vapor deposition, making the atmosphere distribution in this region more uniform. It prevents the atmosphere environment from being disrupted by excessively large unevenness amplitude and / or excessively small unevenness frequency, thus allowing for better deposition of the aforementioned films in this region, improving the passivation effect, and ultimately increasing the power generation efficiency of the solar cell. Here, the specific difference between d4 and d5 is not specifically defined.

[0086] Optionally, in the first direction M, the width of the second conductive region is greater than the width of the first conductive region, as shown in the reference. Figure 4In the first surface of the silicon substrate 1, the region corresponding to the left side of the opening from the left side of L1 to the leftmost side of the transparent conductive layer is the first conductive region. The size of the first conductive region in the first direction M is the width of the first conductive region. In the first surface of the silicon substrate 1, the region between the two L2s is the second conductive region. The size of the second conductive region in the first direction M is the width of the second conductive region. Because the materials of the transport layers on the first and second conductive regions are different, in order to improve production efficiency, different lasers are used to process and treat the first and second transport layers respectively, thereby improving production efficiency. In particular, the second conductive region is wider, which can more thoroughly remove laser damage in this area, resulting in a better quality film layer formed in this region. This improves the film layer quality near the second conductive region in the stacked region, and enhances the passivation effect and / or heat protection. The patterning effect ensures the power generation efficiency of the solar cell. Additionally, the second transport layer may contain a doped polycrystalline silicon layer. This doped polycrystalline silicon layer is laser-processed on the second conductive region. Because the doped polycrystalline silicon layer is difficult to etch, a high-energy laser with a high overlap rate is needed to achieve a wider opening in the doped polycrystalline silicon layer. The first transport layer may contain a doped amorphous silicon layer. This doped amorphous silicon layer is laser-processed on the first conductive region. Because the doped amorphous silicon layer is easier to etch, and it is necessary to minimize the impact on the doped polycrystalline silicon layer underneath during laser processing, a lower-energy laser with a lower overlap rate is needed to achieve a narrower opening in the doped amorphous silicon layer. Furthermore, since the processing width of the doped amorphous silicon layer does not need to be too wide—that is, processing the doped amorphous silicon layer with a single laser spot is sufficient to achieve patterning—the power generation efficiency is maximized.

[0087] Optionally, in the first direction M, the width of the first conductive region is greater than or equal to the spot size of the second laser. Specifically, after the second transmission layer on the first conductive region is treated with the spot opening of the second laser, wet etching may usually be required. After wet etching, the width of the opening will increase. Therefore, the width of the first conductive region is greater than or equal to the spot size of the second laser, which is easy to achieve in the process.

[0088] This application also provides a method for fabricating a back-contact solar cell, which includes the following steps.

[0089] Step 101, providing a silicon substrate; the silicon substrate includes: a first surface and a second surface opposite to each other; the first surface includes: a first conductive region, a second conductive region, and a stacked region located between the first conductive region and the second conductive region; the first conductive region, the stacked region, and the second conductive region are distributed in a first direction.

[0090] The silicon substrate described here is as described above, and will not be repeated here to avoid repetition.

[0091] Step 102: Form a complete first transmission layer on the first surface.

[0092] No specific restrictions are placed on the method of forming the first transport layer. For example, refer to... Figure 5 A tunneling oxide layer 2 (SiO2) was deposited on a silicon substrate 1 using an LPCVD (low-pressure chemical vapor deposition) device. x The tunneling oxide layer 2 consists of an N-type doped polysilicon layer 3 and a dielectric layer 4. The thickness of the tunneling oxide layer 2 can be from 0.5 nm to 5 nm; the thickness of the N-type doped polysilicon layer 3 can be from 30 nm to 300 nm; the thickness of the dielectric layer 4 is from 10 nm to 1000 nm, and the material of the dielectric layer 4 can be SiN. x (Silicon nitride) or SiO x (Silicon oxide), etc., in which x is greater than 0.

[0093] Step 103: Use a first laser to process the portion of the first transmission layer located on the second conductive region, exposing the second conductive region.

[0094] Reference Figure 6 and Figure 7 The portion of the first transmission layer located on the second conductive region is processed by a first laser, followed by wet processing to expose the second conductive region. Figure 6 and Figure 7 The number 5 in the text refers to the disconnection point between the first transport layer and the medium layer 4.

[0095] Specifically, a first laser can be used to break the dielectric layer 4 and the first transport layer. The width of the break point 5 can be between 20 μm and 2000 μm, and the direction of this width is parallel to the first direction M. The first laser used for breaking can be selected with a wavelength of 532 nm and a pulse width of picosecond. Since the film layer to be broken by the first laser is relatively thick, the power of the first laser will be greater than that of the second laser. For example, the power density of the first laser can be 200 mJ / cm². 2 The power range of the first laser can be 100 mJ / cm². 2 Up to 500mJ / cm 2 The first laser can be a 200μm spot with three lines to process the break position 5. The overlap rate of the first laser is about 60%, and the overlap rate can be changed. The higher the power used, the lower the overlap rate can be (for example, the overlap rate of the first laser can be in the range of 0-100%).

[0096] Next, a wet etching step is performed to remove the damaged layer caused by the first laser. Simultaneously, texturing is applied to the disconnection point 5, and the remaining dielectric layer is removed. This step can be done by etching the damaged layer while texturing, or by polishing to remove the damaged layer; the basic purpose is to remove the damaged layer. (Refer to...) Figure 2 This is a schematic diagram of the edge morphology after the first laser cuts off the edge and the cut-off position is etched by wet etching. It can be seen that the side of the first transmission layer near the second conductive region has a first concave-convex morphology extending along the second direction Q. In the first direction M, the concave-convex amplitude of the first concave-convex morphology is R1.

[0097] Step 104: A second transmission layer is formed on the second conductive region and the first transmission layer; the first transmission layer and the second transmission layer have different conductivity types.

[0098] Reference Figure 8 A second transport layer is formed on the second conductive region and the first transport layer; the first and second transport layers have different conductivity types. For example, the first transport layer can be an N-type transport layer, and the second transport layer can be a P-type transport layer. The first transport layer may include a tunneling oxide layer 2 and an N-type doped polycrystalline silicon layer 3. The second transport layer may include an intrinsic amorphous silicon layer 6 and a P-type doped amorphous silicon layer 7.

[0099] Reference Figure 8 This step can also form a front passivation layer 8 and a front antireflection layer 9 on the second surface of the silicon substrate. The front passivation layer 8 can be made of intrinsic amorphous silicon, or the front passivation layer 8 can be made of AlO. x The thicknesses of the (alumina) layer, the intrinsic amorphous silicon layer 6, and the front passivation layer 8 can all range from 3 nm to 20 nm. The thickness of the p-type doped amorphous silicon layer 7 can range from 3 nm to 100 nm. The front antireflection layer 9 can be made of SiN. x (Silicon nitride), the thickness of which can range from 10nm to 300nm.

[0100] Step 105: A second laser is used to process the portion of the second transmission layer located on the first conductive region, exposing the first transmission layer; in the stacked region, at least a portion of the second transmission layer is located on the side of the first transmission layer facing away from the silicon substrate; in the stacked region: the side of the first transmission layer near the second conductive region has a first uneven morphology extending along a second direction, and the side of the second transmission layer near the first conductive region has a second uneven morphology extending along the second direction, the first uneven morphology being different from the second uneven morphology; the second direction intersects the first direction and is perpendicular to the direction of the thickness of the silicon substrate.

[0101] Reference Figure 9A second laser is used to pattern the second transport layer, forming a notch 10. The width of the notch 10 can be between 150 μm and 200 μm, for example, 180 μm, and the direction of the width is parallel to the first direction M. The wavelength of the second laser is 532 nm, and the pulse width is picosecond. The power density used can be 120 mJ / cm², and the usable range of the second laser is 30 mJ / cm². 2 Up to 300mJ / cm 2 A single laser spot can be used, with a spot size of up to 180 μm. The overlap rate of the second laser spot is approximately 10%. When the second laser spot is shaped into a rectangular spot, tangency of the second laser spot is optimal. (Refer to...) Figure 4 The image is an optical microscope image after the second laser process. It can be seen that the side of the second transport layer near the first conductive region has a second uneven morphology extending along the second direction Q. The first uneven morphology is different from the second uneven morphology. The second direction intersects with the first direction and is perpendicular to the direction of the thickness of the silicon substrate.

[0102] The difference between the first and second concave-convex morphologies can be referred to the aforementioned relevant records. For example, in the first direction M, the concave-convex amplitude R1 of the first concave-convex morphology is smaller than the concave-convex amplitude R2 of the second concave-convex morphology.

[0103] The overlap rate of the first laser spot is greater than that of the second laser spot, resulting in the first uneven morphology having an uneven amplitude R1 that is smaller than the second uneven morphology having an uneven amplitude R2.

[0104] Optionally, the power density of the first laser is greater than or equal to the power density of the second laser. Specifically, the total thickness of the first transmission layer and the dielectric layer 4 above it is larger, while the thickness of the second transmission layer is smaller. Therefore, a larger power density is used to break the first transmission layer and the dielectric layer 4 above it.

[0105] Optionally, the first laser spot is at least one of a square spot, a circular spot, and an elliptical spot; and / or, the second laser spot is at least one of a square spot, a circular spot, and an elliptical spot. Laser spots of the above shapes easily achieve the desired overlap rates.

[0106] Optionally, the first laser spot is a square spot with a size ranging from 100 μm to 600 μm. More specifically, it can be between 200 μm and 520 μm. The size of this square spot within this range facilitates control of the overlap rate. For example, the first laser spot can be a square spot with sizes of 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 365 μm, 550 μm, and 600 μm. It should be noted that the size of the first laser spot can be either its length or its width; that is, both the length and width of the first laser spot are between 100 μm and 600 μm.

[0107] Optionally, the second laser spot is a square spot with a size ranging from 50 μm to 300 μm. Further, it can be 180 μm; the size of this square spot within the above range facilitates control of the overlap rate. For example, the second laser spot can be a square spot with sizes of 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 180 μm, 220 μm, and 280 μm. It should be noted that the size of the second laser spot can be either its length or its width; that is, both the length and width of the second laser spot are between 50 μm and 300 μm.

[0108] Optionally, the preparation method may further include: referring to Figure 10 A full-length transparent conductive layer 11 is formed on the side of the first and second transport layers opposite to the silicon substrate 1; (Refer to...) Figure 11 A third laser is used to form an opening 12 at a local location in the stacked region of the transparent conductive layer 11 and the second transport layer. The width of the opening 12 can be from 20 μm to 200 μm. The transparent conductive layer 11 can play a role in energy level matching, which can further improve the performance of the back contact solar cell. The opening 12 here can prevent short circuits. The transparent conductive layer 11 can be deposited using PVD (physical vapor deposition) or RPD (reactive plasma deposition) equipment, and the thickness of the transparent conductive layer 11 can range from 20 nm to 200 nm.

[0109] Optionally, the overlap rate of the third laser spot forming the opening 12 is different from the overlap rate of the first laser spot, and the overlap rate of the third laser spot is different from the overlap rate of the second laser spot. Therefore, the third concave-convex morphology formed on the side of the opposite third and fourth ends of the second transmission layer at an opening, extending along the second direction Q, is different from the shape of the first concave-convex morphology, and the shape of the third concave-convex morphology is also different from the shape of the second concave-convex morphology.

[0110] It should be noted that etching paste can also be used to etch the transparent conductive layer 11. Here, no opening will be formed on the second transport layer, and the first and second transport layers are continuously disposed below the opening.

[0111] Reference Figure 1 Electrode preparation can be carried out using screen printing, and the material of the electrode is not specifically limited.

[0112] The present application will be further explained below with reference to specific embodiments.

[0113] Example

[0114] The first step is to perform wet polishing on the silicon substrate. The wet polishing process mainly includes two steps: cleaning and alkaline polishing.

[0115] The cleaning steps are as follows: (1) Cleaning is performed using SC1 (Standard Clean 1) in the RCA cleaning (industrial standard wet cleaning) process. (2) The residual chemicals from the SC1 cleaning are neutralized by deionized water rinsing. Alkali polishing steps: (1) KOH is used to remove the surface damage layer caused by cutting, and the silicon substrate surface is polished. (2) High-efficiency SC1 cleaning is then performed. (3) SC2 (Standard Clean 2 in industrial standard wet cleaning) is used to remove residual metal ions. (4) Finally, the silicon substrate surface is cleaned with 5% wt (mass concentration 5%) hydrofluoric acid to complete the polishing of the silicon substrate surface. The polishing thickness of the front and back sides of the silicon substrate is 5 μm to 10 μm. The polished silicon substrate surface forms a silicon substrate with different crystal orientations. The silicon substrate includes: a first surface and a second surface opposite to each other. The first surface is the back surface of the subsequent back contact solar cell. The first surface includes: a first conductive region, a second conductive region, and an overlapping region located between the first conductive region and the second conductive region. The first conductive region, the overlapping region, and the second conductive region are distributed in the first direction M.

[0116] The second step, refer to Figure 5 A first transport layer is deposited using an LPCVD device. The first transport layer includes a tunneling oxide layer 2 and an N-type doped polysilicon layer 3. A dielectric layer 4 is also deposited on the first transport layer. The thickness of the tunneling oxide layer 2 can be 3 nm; the thickness of the N-type doped polysilicon layer 3 can be 100 nm; the thickness of the dielectric layer 4 is 300 nm, and the material of the dielectric layer 4 can be silicon nitride. Specifically, the tunneling oxide layer 2 is first prepared in an LPCVD device, then polysilicon is deposited, and then the N-type doped polysilicon layer 3 is prepared using a diffusion device.

[0117] Third step, refer to Figure 6 and Figure 7A first laser is used to remove portions of the first transmission layer and the dielectric layer 4 located on the second conductive region, thus exposing the second conductive region. The first laser can be selected with a wavelength of 532 nm and a pulse width of picosecond. The power density of the first laser can be 200 mJ / cm². 2 The overlap rate of the first laser beams is approximately 60%. (Refer to...) Figure 2 This is a schematic diagram of the edge morphology after the first laser cuts off the edge and the cut-off position is etched by wet etching. It can be seen that the side of the first transmission layer near the second conductive region has a first concave-convex morphology extending along the second direction Q. In the first direction M, the concave-convex amplitude of the first concave-convex morphology is R1.

[0118] Fourth step, refer to Figure 8 A second transport layer is formed on the second conductive region and the first transport layer; the second transport layer may include an intrinsic amorphous silicon layer 6 and a p-type doped amorphous silicon layer 7. A front passivation layer 8 and a front antireflection layer 9 are formed on the second surface of the silicon substrate. The front passivation layer 8 is an intrinsic amorphous silicon layer, and the thickness of both the intrinsic amorphous silicon layer 6 and the front passivation layer 8 can be in the range of 10 nm. The thickness of the p-type doped amorphous silicon layer 7 can be in the range of 40 nm. The front antireflection layer 9 can be made of SiN. x (Silicon nitride), its thickness can be 50nm.

[0119] Step 5, refer to Figure 9 A second laser is used to pattern the second transport layer, forming a notch 10, the width of which can be 180 μm. The wavelength of the second laser is 532 nm, the pulse width is picosecond, and the power density used can be 120 mJ / cm². 2 The second laser uses a single spot with a size of 180 μm. The overlap of the second laser spots is approximately 10%. (Refer to...) Figure 4 The image shown is an optical microscope image after the second laser process. It can be seen that the side of the second transmission layer near the first conductive region has a second uneven morphology extending along the second direction Q. In the first direction M, the unevenness amplitude R1 of the first uneven morphology is smaller than the unevenness amplitude R2 of the second uneven morphology. Wherein, R2 > R1, and d2 < d3.

[0120] Step 6, refer to Figure 10 A full-length transparent conductive layer 11 is formed on the side of the first and second transport layers opposite to the silicon substrate 1; (Refer to...) Figure 11A third laser is used to form an opening 12 at a local location in the stacked region of the transparent conductive layer 11 and the second transport layer. The width of the opening 12 can be 100 μm. The transparent conductive layer 11 can be deposited using a PVD or RPD device, and its thickness can range from 120 nm. The overlap rate of the third laser spot forming the opening 12 is different from that of the first laser spot, and also different from that of the second laser spot. Therefore, the third uneven morphology extending along the second direction Q formed on the side surface of the second transport layer at one opening, including the opposing third and fourth ends, has a different shape than the first uneven morphology, and also different from the shape of the second uneven morphology.

[0121] Step 7, refer to Figure 1 Electrode preparation can be performed using screen printing.

[0122] This application may also provide a photovoltaic module, which may include any of the aforementioned back-contact solar cells. The photovoltaic module may also include encapsulating films located on the light-facing side and the back-light-reflecting side of the back-contact solar cells. The specific structure of the photovoltaic module is not limited.

[0123] It should be noted that the photovoltaic module and the preparation method of the back contact solar cell have the same or similar beneficial effects as any of the aforementioned back contact solar cells, and the three can be referred to each other. To avoid repetition, they will not be described again here.

[0124] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0125] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A back-contact solar cell, characterized in that, include: Silicon substrate; The silicon substrate includes: a first surface and a second surface opposite to each other; the first surface includes: a first conductive region, a second conductive region, and a stacked region located between the first conductive region and the second conductive region; the first conductive region, the stacked region, and the second conductive region are distributed in a first direction; A first transmission layer is located on the first conductive region and the stacked region; A second transport layer is located on the second conductive region and the stacked region, and at least a portion of the second transport layer is located on the side of the first transport layer away from the silicon substrate in the stacked region; the first transport layer and the second transport layer have different conductivity types. In the stacked region: the first transport layer has a first uneven morphology extending along a second direction on the side near the second conductive region, and the second transport layer has a second uneven morphology extending along the second direction on the side near the first conductive region. The first uneven morphology is different from the second uneven morphology. The second direction intersects with the first direction and is perpendicular to the direction of the thickness of the silicon substrate.

2. The back-contact solar cell according to claim 1, characterized in that, The first uneven morphology is different from the second uneven morphology, including: the unevenness amplitude of the first uneven morphology is different from that of the second uneven morphology, and / or the unevenness frequency of the first uneven morphology is different from that of the second uneven morphology.

3. The back-contact solar cell according to claim 2, characterized in that, The unevenness of the first uneven morphology differs from that of the second uneven morphology, including: In the first direction, the concavity and convexity of the first concavity and convexity is smaller than that of the second concavity and convexity. The convexity frequency of the first convexity morphology is different from that of the second convexity morphology, including: In the second direction, the convexity frequency of the first convexity is greater than the convexity frequency of the second convexity.

4. The back-contact solar cell according to claim 1, characterized in that, In the boundary region between the stacked region and the second conductive region, the second transmission layer covers the side of the first transmission layer.

5. The back-contact solar cell according to claim 1, characterized in that, The first uneven topography includes: a first sub-uneven topography and a second sub-uneven topography; along the first direction, a second conductive region includes a first end and a second end opposite to each other; The first sub-concave-convex shape is adjacent to the first end, and the second sub-concave-convex shape is adjacent to the second end; The first sub-concave-convex morphology and the second sub-concave-convex morphology have different concave-convex amplitudes.

6. The back-contact solar cell according to claim 1, characterized in that, Also includes: A transparent conductive layer is disposed at least on the first transmission layer of the first conductive region and on the second transmission layer of the second conductive region; The transparent conductive layer has a break opening, which is provided at least in the stacked region.

7. The back-contact solar cell according to claim 1, characterized in that, Also includes: A transparent conductive layer is disposed on a first transmission layer of the first conductive region, a second transmission layer of the second conductive region, and a second transmission layer of the stacked region; Wherein, at a local location in the stacked region, the transparent conductive layer and the second transport layer have a disconnection opening; Along the first direction, the second transmission layer includes opposing third and fourth ends at one of the openings; The side surface of the third end and the side surface of the fourth end both have a third concave-convex shape, which is different from the first concave-convex shape and the second concave-convex shape.

8. The back-contact solar cell according to claim 7, characterized in that, The third concave-convex morphology differs from the first and second concave-convex morphologies, including: The concavity and convexity of the third concavity and convexity are different from the concavity and convexity of the first concavity and convexity and the concavity and convexity of the second concavity and convexity. And / or, the convexity frequency of the third convexity is different from the convexity frequency of the first convexity and the convexity frequency of the second convexity.

9. The back-contact solar cell according to any one of claims 1 to 8, characterized in that, The first uneven morphology is formed by a first laser, and the second uneven morphology is formed by a second laser; The overlap rate of the first laser beam is greater than that of the second laser beam.

10. The back-contact solar cell according to claim 9, characterized in that, The power density of the first laser is greater than or equal to the power density of the second laser.

11. The back-contact solar cell according to claim 9, characterized in that, The spot size of the first laser is larger than the spot size of the second laser.

12. The back-contact solar cell according to claim 1, characterized in that, The first transport layer has a third surface and a fourth surface opposite to each other, the third surface being the surface of the first transport layer away from the silicon substrate, and the fourth surface being the surface of the first transport layer close to the silicon substrate; The second transport layer has a fifth surface and a sixth surface opposite to each other, the fifth surface being the surface of the second transport layer away from the silicon substrate, and the sixth surface being the surface of the second transport layer close to the silicon substrate; In the thickness direction of the silicon substrate, the distance from the third surface of the first transport layer to the silicon substrate is greater than the distance from the fifth surface of the second transport layer to the fourth surface of the first transport layer.

13. The back-contact solar cell according to any one of claims 1 to 8, characterized in that, In the first direction, the width of the second conductive region is greater than the width of the first conductive region.

14. The back-contact solar cell according to claim 9, characterized in that, In the first direction, the width of the first conductive region is greater than or equal to the spot size of the second laser.

15. The back-contact solar cell according to claim 7, characterized in that, The first uneven morphology is formed by a first laser, the second uneven morphology is formed by a second laser, and the third uneven morphology is formed by a third laser; The beam overlap rate of the third laser is different from that of the first laser, and the beam overlap rate of the third laser is different from that of the second laser.

16. A method for fabricating a back-contact solar cell, characterized in that, include: Provide silicon substrate; The silicon substrate includes: a first surface and a second surface opposite to each other; the first surface includes: a first conductive region, a second conductive region, and a stacked region located between the first conductive region and the second conductive region; the first conductive region, the stacked region, and the second conductive region are distributed in a first direction; A first transport layer, consisting of an entire layer, is formed on the first surface; The portion of the first transmission layer located on the second conductive region is processed using a first laser to expose the second conductive region. A second transport layer is formed on the second conductive region and the first transport layer; the first transport layer and the second transport layer have different conductivity types; A second laser is used to process the portion of the second transmission layer located on the first conductive region, exposing the first transmission layer. In the stacked region, at least a portion of the second transport layer is located on the side of the first transport layer facing away from the silicon substrate; in the stacked region: the side of the first transport layer near the second conductive region has a first uneven morphology extending along a second direction, and the side of the second transport layer near the first conductive region has a second uneven morphology extending along the second direction, the first uneven morphology being different from the second uneven morphology; the second direction intersects the first direction and is perpendicular to the direction of the thickness of the silicon substrate.

17. The method for fabricating a back-contact solar cell according to claim 16, characterized in that, Also includes: A full-length transparent conductive layer is formed on the side of the first and second transport layers opposite to the silicon substrate; A third laser is used to form openings in local locations of the transparent conductive layer and the second transmission layer in the stacked region.

18. A photovoltaic module, characterized in that, include: The back-contact solar cell according to any one of claims 1 to 15.

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