Solar cell and method of manufacturing the same, photovoltaic module

Abstract

This application relates to the field of solar cell technology, and in particular to solar cells and their fabrication methods, and photovoltaic modules. In the embodiments of this application, by configuring the electrodes in the first region of a target surface as including a stacked seed layer and a metal layer, and setting the projected area of ​​the seed layer on the target surface to be smaller than the projected area of ​​the metal layer on the target surface, the seed layer is used to achieve electrical connection between the metal layer and the solar cell substrate. Simultaneously, the distribution density of the seed layer per unit area in the first region is configured to change in a positive correlation with the sheet resistance per unit area in the first region. Therefore, overall, the distribution density of the seed layer is greater in areas with higher sheet resistance in the first region and greater in areas with lower sheet resistance than in the first region, thereby improving current transmission efficiency, increasing cell conversion efficiency, and ultimately improving the performance of the solar cell.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to solar cells and their manufacturing methods, and photovoltaic modules. Background Technology

[0002] A solar cell is a device that converts solar energy into electrical energy. Specifically, a solar cell uses the photovoltaic principle to generate charge carriers, and then uses electrodes to extract these carriers, thus facilitating the efficient use of electrical energy. However, the performance of solar cells needs further improvement. Summary of the Invention

[0003] Therefore, it is necessary to provide a solar cell and its manufacturing method, as well as a photovoltaic module, to improve the performance of solar cells.

[0004] According to one aspect of this application, an embodiment of this application provides a solar cell, including a solar cell substrate, a passivation layer, and an electrode. The solar cell substrate has a first surface and a second surface disposed opposite to each other along a first direction, at least one of the first surface and the second surface being a target surface, the target surface including a first region and a second region. The passivation layer is disposed on the target surface. The electrode is located in the first region, and the electrode includes a stacked seed layer and a metal layer, the seed layer being in contact with the solar cell substrate. The projected area of ​​the seed layer on the solar cell substrate is smaller than the projected area of ​​the metal layer on the solar cell substrate; the distribution density of the seed layer per unit area in the first region shows a positive correlation with the sheet resistance per unit area in the first region.

[0005] In some embodiments, the distribution density of the seed layer in a unit area region of the first region decreases continuously as the sheet resistance of a unit area region of the first region decreases.

[0006] In some embodiments, the sheet resistance per unit area in the first region changes in a negatively correlated trend with the distribution distance; the distribution distance is the distance between the unit area in the first region and the center of the target surface.

[0007] In some embodiments, the sheet resistance per unit area in the first region decreases continuously as the distribution distance increases.

[0008] In some embodiments, the seed layer comprises a plurality of independent seed units.

[0009] In some embodiments, all seed units have the same orthographic projection area and shape on the target surface.

[0010] In some embodiments, the first region and the second region are alternately arranged along the second direction. The first region is provided with a plurality of units and extends along a third direction. The first direction, the second direction and the third direction intersect each other. The first region is provided with a plurality of independent seed units. Along the direction from the center of the first region to the edge of the first region, the spacing between two adjacent seed units along the third direction shows an increasing trend.

[0011] In some embodiments, within the same first region, the spacing between two adjacent seed units increases sequentially along a third direction from the center of the first region to the edge of the first region.

[0012] In some embodiments, in the same first region, along the direction from the center of the first region to the edge of the first region, the ratio q1 of the subsequent preset spacing to the previous preset spacing satisfies: 1 < q1 ≤ 1.2.

[0013] In some embodiments, the spacing between two adjacent seed units along a third direction is a preset spacing, and the minimum preset spacing among all the preset spacings corresponding to all seed units in the first region is the minimum preset spacing; along a third direction, the first region located at the center of the first surface is the middle first region, and the first region located at the edge of the first surface is the edge first region; along the direction from the middle first region to the edge first region, the minimum preset spacing shows an increasing trend.

[0014] In some embodiments, the minimum preset spacing increases sequentially along the direction from the middle first region to the edge first region.

[0015] In some embodiments, along the direction from the middle first region to the edge first region, the ratio q2 of the subsequent minimum preset spacing to the previous minimum preset spacing satisfies: 1 < q2 ≤ 1.5; and / or, the minimum preset spacing corresponding to the middle first region is 20 μm to 200 μm.

[0016] In some embodiments, the first region and the second region are alternately arranged along the second direction. Multiple first regions are provided, and each first region extends along a third direction, with the first direction, the second direction, and the third direction intersecting each other. Multiple independent seed units are provided on each first region. All seed units on the same first region are arranged at equal intervals along the third direction. The projected area of ​​the seed unit on the target surface shows a negative correlation with the arrangement distance; the arrangement distance is the distance between the seed unit and the center of the target surface.

[0017] In some embodiments, the projected area S of the seed unit on the target surface satisfies: 78.5 μm 2 ≤S≤2826μm 2 .

[0018] In some embodiments, the orthographic projection area S of the seed unit on the target surface satisfies: 314 μm 2 ≤S≤706.5μm 2 .

[0019] In some embodiments, the maximum extension dimension L of the seed unit's orthographic projection on the target surface satisfies: 10μm≤L≤60μm.

[0020] In some embodiments, the maximum extension dimension L of the seed unit's orthographic projection on the target surface satisfies: 20μm≤L≤30μm.

[0021] In some embodiments, the shape of the orthographic projection of the seed unit onto the target surface includes a circle, a rectangle, an ellipse, or a serrated shape.

[0022] In some embodiments, the solar cell substrate includes a substrate and functional layers located on both sides of the substrate along a first direction; wherein, one functional layer includes a doped region disposed on the substrate, and the other functional layer includes a tunneling layer and a doped semiconductor layer stacked on the substrate; or, one functional layer includes a first tunneling layer and a first doped semiconductor layer stacked on the substrate, and the other functional layer includes a second tunneling layer and a second doped semiconductor layer stacked on the substrate.

[0023] According to another aspect of this application, embodiments of this application provide a method for manufacturing a solar cell, comprising:

[0024] A solar cell intermediate is provided; the solar cell intermediate includes a solar cell substrate and a passivation layer, the solar cell substrate has a first surface and a second surface disposed opposite to each other along a first direction, at least one of the first surface and the second surface is a target surface, the target surface includes a first region and a second region, and the passivation layer is disposed on the target surface;

[0025] A seed layer is formed in the first region to contact the solar cell substrate; the distribution density of the seed layer in a unit area of ​​the first region is positively correlated with the sheet resistance of a unit area of ​​the first region.

[0026] A metal layer in contact with the seed layer is formed on the side of the passivation layer away from the solar cell substrate to form an electrode, thereby obtaining a solar cell; the orthogonal projection of the metal layer on the target surface is located in a first region, and the orthogonal projection area of ​​the seed layer on the target surface is smaller than the orthogonal projection area of ​​the metal layer on the target surface.

[0027] In some embodiments, a seed layer in contact with the solar cell substrate is formed on a first region, including:

[0028] An initial seed layer is printed on the side of the passivation layer away from the solar cell substrate using a screen printing process; the orthographic projection of the initial seed layer on the target surface is located in the first region; the distribution density of the initial seed layer on the target surface within a unit area of ​​the first region is positively correlated with the sheet resistance of the unit area of ​​the first region.

[0029] The initial seed layer is sintered to form a seed layer that contacts the solar cell substrate.

[0030] In some embodiments, the initial seed layer includes a plurality of independent initial seed units;

[0031] The initial seed layer is sintered to form a seed layer in contact with the solar cell substrate, including:

[0032] Multiple initial seed units are sintered to form multiple seed units in contact with the solar cell substrate; the multiple seed units correspond one-to-one with the multiple initial seed units, and the multiple seed units constitute a seed layer.

[0033] In some embodiments, the process of forming the metal layer includes a metallization heat treatment process or an electroplating process.

[0034] According to another aspect of this application, an embodiment of this application provides a photovoltaic module, including a cell string, an encapsulation layer, and a cover plate. The encapsulation layer is used to cover the surface of the cell string. The cover plate is used to cover the surface of the encapsulation layer away from the cell string. The cell string is formed by connecting multiple solar cells as described in any of the above embodiments; or, the cell string is formed by connecting multiple solar cells manufactured by the method described in any of the above embodiments.

[0035] In the aforementioned solar cells, manufacturing methods, and photovoltaic modules, by configuring the electrodes in the first region of the target surface as including a stacked seed layer and a metal layer, and setting the projected area of ​​the seed layer on the target surface to be smaller than that of the metal layer, the seed layer is used to achieve electrical connection between the metal layer and the solar cell substrate. This not only reduces the contact area between the metal layer and the solar cell substrate, thus lowering contact resistance, but also improves the reliability of the contact between the electrode and the solar cell substrate. Simultaneously, the distribution density of the seed layer per unit area in the first region is configured to change in a positive correlation with the sheet resistance per unit area in the first region. This results in a higher distribution density of the seed layer in areas with higher sheet resistance than in areas with lower sheet resistance, reducing the difference in contact resistance between the seed layer and different regions of the first region. This allows for more uniform conduction of charge carriers along all contact areas, reducing the risk of localized charge carrier accumulation and recombination losses, thereby improving current transport efficiency and cell conversion efficiency. Therefore, the solar cells, manufacturing methods, and photovoltaic modules provided in this application can improve the performance of solar cells.

[0036] Additional aspects and advantages of embodiments of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of embodiments of this application. Attached Figure Description

[0037] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the embodiments described below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0038] Figure 1 This is a partial cross-sectional view of the solar cell in some embodiments of this application;

[0039] Figure 2 This is a top view of the solar cell structure in some embodiments of this application;

[0040] Figure 3 This is a partial structural diagram of the first region in some embodiments of this application;

[0041] Figure 4 This is a schematic diagram of the distribution structure of seed units in a first region in some embodiments of this application;

[0042] Figure 5 This is a partial cross-sectional view of the solar cell in some other embodiments of this application;

[0043] Figure 6 This is a partial cross-sectional view of the solar cell in some embodiments of this application;

[0044] Figure 7 This is a schematic flowchart illustrating the method for manufacturing a solar cell in some embodiments of this application;

[0045] Figure 8 This is a flowchart illustrating step S120 in some embodiments of this application;

[0046] Figure 9 This is a flowchart illustrating step S122 in some embodiments of this application;

[0047] Figure 10 This is a schematic diagram of the structure of a photovoltaic module in some embodiments of this application.

[0048] Explanation of reference numerals in the attached figures:

[0049] Solar cells 100, 100a, 100b;

[0050] A solar cell substrate 110 has a first surface m1, a second surface m2, a first region z1, a unit area region z0, a middle first region z1a, an edge first region z1b, and a second region z2.

[0051] Solar cell substrates 110a and 110b, substrate 111, doped region 112, tunneling layer 113, doped semiconductor layer 114, first tunneling layer 113a, first doped semiconductor layer 114a, second tunneling layer 113b, second doped semiconductor layer 114b.

[0052] Passivation layer 120;

[0053] Electrode 130, seed layer 131, seed unit 1311, metal layer 132;

[0054] Preset spacing h, minimum preset spacing h min Diameter D;

[0055] Photovoltaic module 10, cell string 11, encapsulation layer 12, cover plate 13, conductive strip 14;

[0056] First direction F1, second direction F2, third direction F3. Detailed Implementation

[0057] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0058] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application.

[0059] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0060] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can be a mechanical connection or an electrical connection; they can be 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, unless otherwise expressly limited. It is worth noting that in the following description and the appended claims, "electrical connection" between one feature and another not only includes direct contact between the two features to form an electrical energy transmission or current transmission channel, but also includes an intermediate feature between the two features, which, along with the intermediate feature, forms an electrical energy transmission or current transmission channel to achieve electrical energy transmission or transmission. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0061] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0062] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0063] According to some embodiments of this application, please refer to Figure 1 and Figure 2 , Figure 1 This is a partial cross-sectional view of the solar cell 100 in some embodiments of this application. Figure 2 This is a top view schematic diagram of a solar cell 100 according to some embodiments of this application. The embodiments of this application provide a solar cell 100, including a solar cell substrate 110, a passivation layer 120, and an electrode 130. The solar cell substrate 110 has a first surface m1 and a second surface m2 disposed opposite each other along a first direction F1. At least one of the first surface m1 and the second surface m2 is a target surface, which includes a first region z1 and a second region z2. The passivation layer 120 is disposed on the target surface. The electrode 130 is located in the first region z1 and includes a stacked seed layer 131 and a metal layer 132. The seed layer 131 is in contact with the solar cell substrate 110. The projected area of ​​the seed layer 131 on the solar cell substrate 110 is smaller than the projected area of ​​the metal layer 132 on the solar cell substrate 110. The distribution density of the seed layer 131 within a unit area region z0 of the first region z1 shows a positive correlation with the sheet resistance of the unit area region z0 of the first region z1.

[0064] The solar cell substrate 110 includes a substrate 111 and a functional layer disposed on the substrate 111. Figure 1For example, the first direction F1 is the thickness direction of the solar cell substrate 110, and the second direction F2 and the third direction F3 can be the length direction and the width direction of the solar cell substrate 110, respectively. The first direction F1, the second direction F2, and the third direction F3 are perpendicular to each other. It should be noted that the dimension of the solar cell substrate 110 along the length direction can be greater than or equal to the dimension along the width direction, and no specific restriction is imposed here.

[0065] At least one of the first surface m1 and the second surface m2 is the target surface; that is, either the first surface m1 or the second surface m2 can be the target surface, or both the first surface m1 and the second surface m2 can be the target surface. Figure 1 For example, the case where both the first surface m1 and the second surface m2 are target surfaces is illustrated.

[0066] The passivation layer 120 can effectively passivate the target surface of the solar cell substrate 110, reduce the interface state density, thereby reducing minority carrier recombination, improving the carrier transport efficiency at the interface, and increasing the efficiency of the solar cell 100. The passivation layer 120 can also reduce or eliminate reflected light on the surface of the solar cell 100 and increase light transmittance, further improving the photoelectric conversion efficiency of the solar cell 100.

[0067] For example, the passivation layer 120 can be formed by plasma enhanced chemical vapor deposition (PECVD), but other methods, such as organic chemical vapor deposition, can also be used to form the passivation layer 120.

[0068] The passivation layer 120 can be a single-layer structure, a multilayer structure, or a combination of single-layer and multilayer structures, and the thickness of each layer can be designed accordingly, without limitation. For example, the passivation layer 120 can be any one or more combinations of silicon nitride, silicon oxynitride, silicon oxide, and aluminum oxide. Of course, the passivation layer 120 can also use other types of layers, without specific limitations.

[0069] Electrode 130 includes a seed layer 131 and a metal layer 132. The seed layer 131 is in contact with the solar cell substrate 110, enabling current collection and conduction, thereby forming an electrical connection between the metal layer 132 and the solar cell substrate 110. That is, since both the seed layer 131 and the metal layer 132 are conductive materials, the seed layer 131 and the solar cell substrate 110, and the seed layer 131 and the metal layer 132, form a physical channel for carrier flow through their physical contact. When the solar cell 100 is not in a power generation or supply state, the carriers are not effectively separated and driven to flow, and the carriers do not flow through this physical channel. When the solar cell 100 is in a power generation or supply state, the solar cell substrate 110 generates carriers, which are separated under the influence of its built-in electric field, and the carriers flow through this physical channel.

[0070] Electrode 130 is located in the first region z1, that is, both seed layer 131 and metal layer 132 are located in the first region z1. The projected area of ​​seed layer 131 on solar cell substrate 110 is smaller than the projected area of ​​metal layer 132 on solar cell substrate 110. That is, a part of metal layer 132 is in contact with seed layer 131, while another part of metal layer 132 is not in contact with seed layer 131, thereby reducing the contact area between metal layer 132 and solar cell substrate 110.

[0071] The unit area on the first region z1 is relative to the target surface of the solar cell substrate 110 and is related to the area of ​​the first region z1 on the target surface. The unit area region z0 is a region selected from the first region z1 on the target surface. The size and shape of the selected unit area region z0 depend on the different definitions of unit area size. After the unit area size is defined, the size of the unit area region z0 has a relative size and shape with respect to the first region z1. For example, the size of the unit area region z0 can be 1 cm. 2 (square centimeters), or 1 mm 2 (square millimeters), or 11mm 2 The size of a unit area, such as (square millimeters), can be determined based on the size of the first region z1 and the usage requirements; this embodiment does not impose specific limitations on this. Similarly, the division of the unit area region z0 can be customized according to the usage. For example, the first region z1 can be divided into N×M square regions of equal area, each region being a unit area region z0, where N and M are preset positive integers, and the selection of N and M is determined by the size of the first region z1. Of course, the shape of each unit area region z0 is not limited to a square. It is understood that the shape and size of each unit area region z0 are the same.

[0072] For example, in conjunction with reference Figure 3 , Figure 3 This is a partial structural diagram of the first region z1 in some embodiments of this application. Figure 3 The diagram illustrates the situation where the first region z1 is divided into unit area regions z0 along the second direction F2 and the third direction F3. The unit area regions z0 are arranged in a square. Multiple unit area regions z0 are arranged in an array along the second direction F2 and the third direction F3. Two adjacent unit area regions z0 along the second direction F2 are adjacent to each other, and two adjacent unit area regions z0 along the third direction F3 are adjacent to each other.

[0073] Of course, in some other embodiments, the shape of the unit area region z0 can also be a rectangle or other shapes. The unit area region z0 divided on the first region z1 may include an incomplete unit area region z0. For example, after dividing the unit area region z0 according to usage requirements, the remaining area is insufficient to divide a complete unit area region z0. The remaining area can be converted according to usage requirements. Figure 3 The illustrated scenarios all demonstrate that the first region z1 is divided into multiple complete unit-area regions z0. This can be configured according to usage, and no specific restrictions are imposed here.

[0074] The distribution density of seed layer 131 within a unit area region z0 of the first region z1 is the ratio of the area occupied by seed layer 131 within a unit area region z0 to the area of ​​that unit area region z0. The distribution density within a unit area region z0 characterizes the density of seed layer 131 distribution. For example, the distribution density within a unit area region z0 refers to the proportion of area occupied by seed layer 131 within that unit area region z0. The lower the distribution density of seed layer 131 within a unit area region z0, the sparser the distribution of seed layer 131, and vice versa.

[0075] The positive correlation trend refers to the relationship between the "distribution density of seed layer 131 within a unit area region z0 of the first region z1" and the "sheet resistance of a unit area region z0 of the first region z1". When the sheet resistance of a unit area region z0 of the first region z1 increases, the distribution density of seed layer 131 within a unit area region z0 of the first region z1 also tends to increase. When the sheet resistance of a unit area region z0 of the first region z1 decreases, the distribution density of seed layer 131 within a unit area region z0 of the first region z1 also tends to decrease. In other words, an increase or decrease in the sheet resistance of a unit area region z0 of the first region z1 does not necessarily lead to an increase or decrease in the distribution density of seed layer 131 within a unit area region z0 of the first region z1, as long as the "distribution density of seed layer 131 within a unit area region z0 of the first region z1" and the "sheet resistance of a unit area region z0 of the first region z1" show a roughly positive correlation trend.

[0076] For example, the positive correlation trend change can be that as the sheet resistance of the unit area region z0 on the first region z1 decreases, the distribution density of the seed layer 131 in the unit area region z0 on the first region z1 can first remain unchanged and then decrease, or it can first decrease and then remain unchanged, or it can decrease continuously, or it can first decrease, then remain unchanged and then decrease again. No specific restrictions are made here.

[0077] Therefore, by configuring the electrode 130 in the first region z1 of the target surface to include a stacked seed layer 131 and a metal layer 132, and setting the orthogonal projection area of ​​the seed layer 131 on the target surface to be smaller than the orthogonal projection area of ​​the metal layer 132 on the target surface, the electrical connection between the metal layer 132 and the solar cell substrate 110 is achieved by using the seed layer 131. In this way, not only can the contact area between the metal layer 132 and the solar cell substrate 110 be reduced, which is beneficial to reducing the contact resistance, but also the reliability of the contact between the electrode 130 and the solar cell substrate 110 can be improved. Simultaneously, the distribution density of the seed layer 131 within a unit area region z0 of the first region z1 is configured to exhibit a positive correlation with the sheet resistance of the unit area region z0 of the first region z1. This results in a higher overall distribution density of the seed layer 131 in regions with higher sheet resistance than in regions with lower sheet resistance. This reduces the difference in contact resistance between the seed layer 131 and different areas of the first region z1, allowing for more uniform conduction of charge carriers across all contact areas. This lowers the risk of localized charge carrier accumulation and recombination losses, thereby improving current transport efficiency and cell conversion efficiency. Consequently, the performance of the solar cell 100 can be enhanced.

[0078] It should be noted that, compared with the method of uniformly distributing the seed layer, the arrangement of the seed layer 131 provided in this application embodiment is combined with the variation law of sheet resistance, which is more conducive to reducing the difference in contact resistance, and thus has a greater advantage in improving the performance of solar cells.

[0079] It should also be noted that, in the embodiments of this application, the sheet resistance of the first region z1 can be detected by any method known to those skilled in the art. Those skilled in the art can choose the appropriate method based on their needs, for example, it can be tested using a four-probe tester. Those skilled in the art will understand that the sheet resistance of the first region z1 can be the sheet resistance detection data of any point in the first region z1, or it can be the average of the sheet resistance detection data from multiple points. Those skilled in the art can select any of the above-mentioned points for detection based on the detection conditions and the instruments used, or they can detect multiple points and calculate the average of the multiple points as the sheet resistance of the first region z1.

[0080] In this embodiment, the selection of the unit area region z0 on the first region z1 can be made according to the actual usage. For example, the sheet resistance of the unit area region z0 corresponding to the first region z1 can be calculated by selecting multiple sites of the unit area region z0 to calculate the average value, and the average value is used to characterize the sheet resistance of the unit area region z0. These multiple sites can be randomly selected on the unit area region z0, for example, arbitrarily selecting 2 sites, 3 sites, 4 sites, 5 sites, 6 sites, 7 sites, 8 sites, 9 sites, 10 sites or more for detection and calculation. Of course, it is also possible to select one site on the unit area region z0 corresponding to the first region z1 for detection and calculation.

[0081] In this embodiment, the distribution density of the seed layer 131 within a unit area region z0 on the first region z1 can be detected by any method known to those skilled in the art. Those skilled in the art can choose based on their needs; for example, they can use a scanning electron microscope (SEM) to acquire images of the solar cell 100 with the metal layer 132 removed. On the obtained SEM top view, at least one unit area of ​​the same size, for example, 1 cm², can be selected. 2 The area ratio of the seed layer 131 in each region is calculated, which is the distribution density of the seed layer 131 in the unit area region z0 on the first region z1. For example, the metal layer 132 can be removed by scraping. The area of ​​the seed unit 1311 and the maximum extension dimension L mentioned below can also be calculated by image acquisition using the scanning electron microscope mentioned above, and will not be repeated here.

[0082] Based on some embodiments of this application, please continue to refer to Figure 1 and Figure 2 The distribution density of seed layer 131 within a unit area region z0 in the first region z1 decreases continuously as the sheet resistance of the unit area region z0 in the first region z1 decreases. That is, as the sheet resistance of the unit area region z0 in the first region z1 decreases, the distribution density of seed layer 131 within the corresponding unit area region z0 decreases.

[0083] For example, when the sheet resistance of a unit area region z0 in the first region z1 increases, the distribution density of seed layer 131 within the unit area region z0 in the first region z1 will also increase. Conversely, when the sheet resistance of a unit area region z0 in the first region z1 decreases, the distribution density of seed layer 131 within the unit area region z0 in the first region z1 will also decrease. The trends of change in "distribution density of seed layer 131 within the unit area region z0 in the first region z1" and "sheet resistance of a unit area region z0 in the first region z1" are completely synchronized. There is no situation where the sheet resistance of a unit area region z0 in the first region z1 decreases but the distribution density of seed layer 131 within the unit area region z0 in the first region z1 increases, or where the sheet resistance of a unit area region z0 in the first region z1 changes but the distribution density of seed layer 131 within the unit area region z0 in the first region z1 remains unchanged.

[0084] Continuous decrease means that the change in the distribution density of seed layer 131 within a unit area region z0 of the first region z1 is smooth and gradual, rather than sudden. For example, as the sheet resistance of a unit area region z0 within the first region z1 gradually decreases, the distribution density of seed layer 131 within a unit area region z0 of the first region z1 will not jump directly from a high value to a low value. Throughout the entire change process, the magnitude of the distribution density of seed layer 131 within a unit area region z0 of the first region z1 is continuous, without any numerical gaps or sudden breaks.

[0085] In other words, the distribution density of seed layer 131 within a unit area region z0 of the first region z1 is positively correlated with the sheet resistance of the unit area region z0 of the first region z1, and the decrease in the distribution density of seed layer 131 within a unit area region z0 of the first region z1 is continuous and without jumps. For every slight decrease in sheet resistance of the unit area region z0 of the first region z1, the distribution density of seed layer 131 within the unit area region z0 of the first region z1 will decrease accordingly, without any sudden, abrupt changes.

[0086] Thus, by further controlling the distribution density of the seed layer 131 within the unit area region z0 on the first region z1, the contact resistance between the electrode 130 and the solar cell substrate 110 can be further controlled, thereby further reducing the difference in contact resistance between the seed layer 131 and each region of the first region z1, and further improving the current transmission efficiency.

[0087] Of course, in some other embodiments, the distribution density of the seed layer 131 within a unit area region z0 on the first region z1 may decrease in stages as the sheet resistance of the unit area region z0 on the first region z1 decreases. That is, as the sheet resistance of the unit area region z0 on the first region z1 decreases, the distribution density of the seed layer 131 within a unit area region z0 on the first region z1 may first remain unchanged, then decrease, and then remain unchanged again; or it may first decrease, then remain unchanged, and then decrease again, etc., without specific limitations here.

[0088] Based on some embodiments of this application, please continue to refer to Figure 1 and Figure 2 The sheet resistance of a unit area region z0 within the first region z1 shows a negative correlation with the distribution distance. The distribution distance is the distance between a unit area region z0 within the first region z1 and the center of the target surface. In other words, the sheet resistance of the first region z1 is generally larger in the middle and smaller at the edges.

[0089] The negative correlation trend can be understood by referring to the positive correlation trend illustrated above. The difference is that they are opposite trends; that is, the positive correlation trend is that both increase or decrease together, while the negative correlation trend is that one increases while the other decreases. This will not be elaborated further here.

[0090] Based on the relevant manufacturing processes of the solar cell substrate 110, such as diffusion and deposition processes, it is easy to form a situation where the sheet resistance is large in the middle and small at the edges. At this time, since the distribution density corresponding to the seed layer 131 varies with the sheet resistance of the unit area region z0 on the first region z1, the distribution density corresponding to the seed layer 131 is generally in a state of large in the middle and small at the edges.

[0091] In this way, by controlling the distribution density of the seed layer 131 according to the sheet resistance state formed by the process, the contact resistance difference of each region can be reduced, the carrier collection capacity of each region can be fully utilized, the fill factor can be improved, and the battery efficiency can be improved.

[0092] Based on some embodiments of this application, please continue to refer to Figure 1 and Figure 2 The sheet resistance of a unit area region z0 in the first region z1 decreases continuously as the distribution distance increases.

[0093] The meaning of continuous decrease can be understood by referring to the situations shown in some of the aforementioned embodiments, and will not be repeated here. Unlike some of the aforementioned embodiments, this reflects the relationship between "the sheet resistance of a unit area region z0 on the first region z1" and "distribution distance".

[0094] Thus, the distribution density corresponding to the seed layer 131 can be further controlled based on the further variation law of the sheet resistance. For example, the distribution density of the seed layer 131 in a unit area region z0 on the first region z1 can be continuously reduced as the sheet resistance of the unit area region z0 on the first region z1 decreases.

[0095] Based on some embodiments of this application, please continue to refer to Figure 2 Seed layer 131 includes multiple independent seed units 1311.

[0096] The distribution density of seed layer 131 within a unit area region z0 on the first region z1 is the ratio of the area occupied by seed units 1311 within a unit area region z0 to the area of ​​that unit area region z0. The distribution density within a unit area region z0 characterizes the density of seed units 1311. For example, the distribution density within a unit area region z0 refers to the proportion of area occupied by seed units 1311 within that unit area region z0. The lower the distribution density of seed units 1311 within a unit area region z0, the sparser the distribution of seed units 1311, and vice versa.

[0097] If all seed units 1311 are the same size and all seed units 1311 within a unit area region z0 are completely located within that unit area region z0, then the area occupied by seed units 1311 within the unit area region z0 is equal to the number of seed units 1311 within the unit area region z0 multiplied by the area occupied by a single seed unit 1311. If all seed units 1311 are not completely the same size and some seed units 1311 within a unit area region z0 are complete while others are incomplete, then the area occupied by seed units 1311 within a unit area region z0 is the sum of the total area occupied by all complete seed units 1311 within the unit area region z0 and the total area occupied by all incomplete seed units 1311 within the unit area region z0. Of course, depending on the division of different unit area regions z0, one seed unit 1311 can also be set on each unit area region z0. By controlling the size of the seed units 1311 on different unit area regions z0, that is, controlling the distribution density of the seed layer 131 within the unit area region z0 of the first region z1. No specific restrictions are imposed here.

[0098] Thus, by setting the seed layer 131 as multiple independent seed units 1311, it is convenient to manufacture the seed layer 131 while controlling the distribution density of the seed layer 131.

[0099] Of course, in some other embodiments, the seed layer 131 may not be a plurality of independent seed units 1311. For example, the seed layer 131 may be a continuous structure, and the distribution density of the seed layer 131 can be controlled by controlling the width of the seed layer 131 in different unit area regions z0. No specific limitation is made here.

[0100] Based on some embodiments of this application, please continue to refer to Figure 2 All seed units 1311 have the same orthographic projection area and shape on the target surface.

[0101] Thus, since the seed units 1311 are the same in size and shape, not only can the distribution density of the seed units 1311 be controlled based on the same seed units 1311, but it is also convenient to manufacture the seed units 1311.

[0102] Of course, in some other embodiments, the orthographic projection area of ​​the seed unit 1311 on the target surface may be different, and the shape may also be different, which is not specifically limited here.

[0103] Based on some embodiments of this application, please continue to refer to Figure 1 and Figure 2 and in conjunction with reference Figure 4 , Figure 4 This is a schematic diagram of the distribution structure of seed units 1311 on a first region z1 in some embodiments of this application. The first region z1 and the second region z2 are alternately arranged along the second direction F2. Multiple first regions z1 are provided, and the first region z1 extends along a third direction F3. The first direction F1, the second direction F2, and the third direction F3 intersect each other. Multiple independent seed units 1311 are provided on the first region z1. Along the direction from the center of the first region z1 to its edge, the spacing between two adjacent seed units 1311 along the third direction F3 shows an increasing trend.

[0104] For example, in the embodiments of this application, the first direction F1, the second direction F2, and the third direction F3 are perpendicular to each other.

[0105] For example, the size and shape of the seed unit 1311 may be the same or different.

[0106] For example, with Figure 2 and Figure 4For example, all seed units 1311 on the same first region z1 are arranged at intervals along the third direction F3. The distance between two adjacent seed units 1311 along the third direction F3 is a preset distance h. Thus, there are multiple preset distances h corresponding to the same first region z1. Among all the preset distances h, the preset distance h increases in the direction from the center of the first region z1 to the edge of the first region z1. That is, the preset distance h generally increases in the direction from the center of the first region z1 to the edge of the first region z1. The preset distance h can remain unchanged first and then increase, or it can increase first, remain unchanged, and then increase again, or it can increase continuously. No specific restrictions are made here.

[0107] Thus, by determining the spacing between two adjacent seed units 1311 along the third direction F3, it is not only easier to control the distribution density of the seed units 1311, but also easier to manufacture. Furthermore, if all seed units 1311 have the same orthographic projection area and shape on the target surface, it is even more advantageous to control and manufacture them.

[0108] Based on some embodiments of this application, please continue to refer to Figure 2 and Figure 4 Within the same first region z1, the spacing between two adjacent seed units 1311 increases sequentially along the direction from the center of the first region z1 to its edge. That is, along the direction from the center of the first region z1 to its edge, the previous preset spacing h is smaller than the next preset spacing h.

[0109] Thus, by further controlling the spacing between two adjacent seed units 1311 along the third direction F3, it is easier to control the distribution density of seed units 1311 more precisely, thereby enabling more accurate control of contact resistance.

[0110] Based on some embodiments of this application, please continue to refer to Figure 2 and Figure 4 In the same first region z1, along the direction from the center of the first region z1 to the edge of the first region z1, the ratio q1 of the subsequent preset spacing h to the previous preset spacing h satisfies: 1<q1≤1.2.

[0111] For example, q1 can be 1.01, 1.02, 1.05, 1.1, 1.15 or 1.2, and q1 can be any value within the aforementioned range, without any specific restrictions.

[0112] Thus, by controlling the ratio of the next preset spacing h to the previous preset spacing h, the distribution density of the seed layer 131 can be controlled more accurately.

[0113] It should be noted that the ratio q1 corresponding to the same first region z1 can be the same or different, and no specific restrictions are imposed here.

[0114] Based on some embodiments of this application, please continue to refer to Figure 2 and Figure 4 The spacing between two adjacent seed units 1311 along the third direction F3 is the preset spacing h, and the minimum preset spacing h among all the preset spacings h corresponding to all seed units 1311 in the first region z1 is the minimum preset spacing h. min Along the third direction F3, the first region z1 located at the center of the first surface m1 is the central first region z1a, and the first region z1 located at the edge of the first surface m1 is the edge first region z1b. The minimum preset spacing h along the direction from the central first region z1a to the edge first region z1b... min It shows an increasing trend.

[0115] The increasing trend can be understood by referring to the situations illustrated in some of the aforementioned embodiments, and will not be repeated here.

[0116] Thus, based on the positional distribution of the first region z1, the distribution density of seed units 1311 in different first regions z1 can be further controlled, which is more conducive to controlling the distribution density of seed units 1311 from the middle to the edge.

[0117] Based on some embodiments of this application, please continue to refer to Figure 2 and Figure 4 The minimum preset spacing h is along the direction from the middle first region z1a to the edge first region z1b. min The spacing increases sequentially. That is, along the direction from the middle first region z1a to the edge first region z1b, the previous minimum preset spacing h... min Less than the next minimum preset spacing h min .

[0118] Thus, by further controlling the minimum preset spacing h on different first regions z1 min This allows for more precise control of the distribution density of the seed unit 1311, thereby enabling more accurate control of the contact resistance.

[0119] Based on some embodiments of this application, please continue to refer to Figure 2 and Figure 4 Along the direction from the middle first region z1a to the edge first region z1b, the next minimum preset spacing h min The minimum preset distance h from the previous minThe ratio q2 satisfies: 1 < q2 ≤ 1.5. That is, along the direction from the middle first region z1a to the edge first region z1b, the minimum preset spacing h corresponding to the next first region z1 is... min The minimum preset spacing h corresponding to the previous first region z1 min The ratio q2 satisfies the aforementioned range.

[0120] For example, q2 can be 1.01, 1.02, 1.05, 1.1, 1.2, 1.4, or 1.5. q2 can be any value within the aforementioned range, without specific restrictions.

[0121] Thus, by controlling the next minimum preset spacing h min The minimum preset distance h from the previous min The ratio of the seed layer 131 can be used to more accurately control its distribution density.

[0122] It should be noted that all ratios q2 can be the same or different; no specific restrictions are imposed here.

[0123] Based on some embodiments of this application, please continue to refer to Figure 2 and Figure 4 The minimum preset spacing h corresponding to the first region z1a in the middle min The spacing ranges from 20 μm to 200 μm. For example, the minimum preset spacing h corresponds to the first intermediate region z1a. min It can be 20μm, 3μm, 50μm, 70μm, 100μm, 120μm, 130μm, 180μm or 200μm, and can be any value in the range of 20μm to 200μm, without specific restrictions.

[0124] Thus, by controlling the minimum preset spacing h corresponding to the first intermediate region z1a min This allows for easy control of the distribution density of the seed layer 131 while ensuring a certain level of connection reliability for the metal layer 132.

[0125] Based on some embodiments of this application, please continue to refer to Figure 2 and Figure 4 All the first regions z1 constitute a first edge region group, a middle region group, and a second edge region group. The first edge region group, the middle region group, and the second edge region group are arranged sequentially along the second direction F2. The first edge region group includes multiple first regions z1 spaced apart along the second direction F2; the middle region group includes multiple first regions z1 spaced apart along the second direction F2; and the second edge region group includes multiple first regions z1 spaced apart along the second direction F2. The minimum preset spacing h corresponding to all the first regions z1 in the middle region group is... minSimilarly, the minimum preset spacing h corresponding to all first regions z1 in the first edge region group min Similarly, the minimum preset spacing h corresponding to all first regions z1 in the second edge region group min Same. The minimum preset spacing h corresponding to the middle region group. min The minimum preset spacing h corresponding to the first edge region group is less than min and the minimum preset spacing h corresponding to the second edge region group. min .

[0126] In this way, all the first regions z1 are divided into three regions, which facilitates both control of the distribution density of the seed layer 131 and ease of fabrication.

[0127] Based on some embodiments of this application, please continue to refer to Figure 2 Seed units 1311 on all first regions z1 except the middle first region z1a are symmetrically arranged about the middle first region z1a; and seed units 1311 on all first regions z1 except the middle first region z1a are symmetrically arranged about a reference line that passes through the center of the target surface and is parallel to the second direction F2.

[0128] In this way, by arranging the seed units 1311 in a regular manner, it is not only easy to manufacture, but also easy to control the distribution density of the seed units 1311.

[0129] According to some embodiments of this application, a first region z1 and a second region z2 are alternately arranged along a second direction F2. Multiple first regions z1 are provided, and each first region z1 extends along a third direction F3. The first direction F1, the second direction F2, and the third direction F3 intersect each other. Multiple independent seed units 1311 are provided on the first region z1. All seed units 1311 on the same first region z1 are arranged at equal intervals along the third direction F3. The projected area of ​​the seed unit 1311 on the target surface shows a negative correlation with the arrangement distance. The arrangement distance is the distance between the seed unit 1311 and the center of the target surface.

[0130] The changes in the negative correlation trend can be understood by referring to the situations illustrated in some of the aforementioned embodiments, and will not be repeated here.

[0131] Thus, based on the equally spaced seed units 1311, the distribution density of the seed units 1311 can be controlled by controlling the size of the seed units 1311, which is beneficial for more accurate control of the required distribution density.

[0132] According to some embodiments of this application, the shape of the orthographic projection of the seed unit 1311 onto the target surface includes a circle, a rectangle, an ellipse, or a serrated shape.

[0133] For example, with Figure 2 and Figure 4 For example, the orthographic projection of the seed unit 1311 onto the target surface is circular.

[0134] In this way, the shape of the orthographic projection of the seed unit 1311 on the target surface can be flexibly set, without any specific restrictions.

[0135] Based on some embodiments of this application, please continue to refer to Figure 2 and Figure 4 The projected area S of seed unit 1311 on the target surface satisfies: 78.5 μm 2 ≤S≤2826μm 2 .

[0136] For example, the orthographic projection area S of the seed unit 1311 on the target surface can be 78.5 μm. 2 85μm 2 105μm 2 305μm 2 500μm 2 700μm 2 1000μm 2 1500μm 2 2000μm 2 2500μm 2 Or 2826μm 2 The orthographic projection area S of the seed unit 1311 on the target surface can be any value within the aforementioned range, and no specific restrictions are imposed here.

[0137] Thus, by controlling the projected area of ​​the seed unit 1311, it is not only beneficial to control the distribution density of the seed unit 1311, but also beneficial to improve the contact performance and the connection reliability of the metal layer 132 while making the seed unit 1311.

[0138] Based on some embodiments of this application, please continue to refer to Figure 2 and Figure 4 The orthographic projection area S of seed unit 1311 on the target surface satisfies: 314 μm 2 ≤S≤706.5μm 2 .

[0139] For example, the projected area S of the seed unit 1311 on the target surface can be 314 μm. 2 400μm 2 430μm 2 500μm 2 600μm 2 700μm 2Or 706.5μm 2 The orthographic projection area S of the seed unit 1311 on the target surface can be any value within the aforementioned range, and no specific restrictions are imposed here.

[0140] Thus, by further controlling the projected area of ​​the seed unit 1311, it is not only beneficial to further control the distribution density of the seed unit 1311, but also beneficial to improve the contact performance and the connection reliability of the metal layer 132 while further fabricating the seed unit 1311.

[0141] Based on some embodiments of this application, please continue to refer to Figure 2 and Figure 4 The maximum extension dimension L of the orthographic projection of seed unit 1311 on the target surface satisfies: 10μm≤L≤60μm.

[0142] For example, the maximum extension L of the orthographic projection of the seed unit 1311 onto the target surface is 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 55 μm, or 60 μm. The maximum extension L can be any value within the aforementioned range, and no specific limitation is imposed here.

[0143] For example, with Figure 2 and Figure 4 For example, the orthographic projection of the seed unit 1311 onto the target surface is a circle, that is, the diameter D of the orthographic projection of the seed unit 1311 onto the target surface satisfies: 10μm≤D≤60μm.

[0144] Thus, by controlling the maximum extension dimension of the orthographic projection of the seed unit 1311 on the target surface, that is, controlling the area of ​​the orthographic projection of the seed unit 1311 on the target surface, the distribution density of the seed unit 1311 can be controlled by controlling the size of the seed unit 1311. Through the aforementioned limitation, both controllability and fabrication are facilitated.

[0145] Based on some embodiments of this application, please continue to refer to Figure 2 and Figure 4 The maximum extension dimension L of the orthographic projection of seed unit 1311 on the target surface satisfies: 20μm≤L≤30μm.

[0146] For example, the maximum extension L of the orthographic projection of the seed unit 1311 onto the target surface is 20 μm, 23 μm, 25 μm, 28 μm, 29 μm, or 30 μm. The maximum extension L can be any value within the aforementioned range, and no specific limitation is imposed here.

[0147] Thus, by further controlling the maximum extension dimension of the orthographic projection of the seed unit 1311 on the target surface, it is possible to facilitate the control of the distribution density of the seed unit 1311 while also facilitating its fabrication and reducing manufacturing costs.

[0148] According to some embodiments of this application, please refer to Figure 5 , Figure 5 This is a partial cross-sectional view of a solar cell 100a in some other embodiments of this application. The solar cell substrate 110a includes a substrate 111 and functional layers located on both sides of the substrate 111 along a first direction F1. One of the functional layers includes a doped region 112 disposed on the substrate 111, and the other functional layer includes a tunneling layer 113 and a doped semiconductor layer 114 stacked on the substrate 111.

[0149] The substrate 111 is used to receive incident light and generate photogenerated carriers. The substrate 111 can be selected according to actual needs. For example, the substrate 111 can be a silicon substrate, which may include one or more of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. The doping type of the substrate 111 is not specifically limited. For example, the substrate 111 can be an N-type doped silicon substrate, or it can be a P-type doped silicon substrate; there is no specific limitation in this regard. The N-type doping element can be a group V element such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As), and the P-type doping element can be a group III element such as boron (B), aluminum (Al), gallium (Ga), or indium (In). In the embodiments of this application, the substrate 111 can be an N-type monocrystalline silicon wafer, which can improve the conversion efficiency of the solar cell 100 and reduce manufacturing costs.

[0150] The substrate 111 has two surfaces disposed opposite to each other along a first direction F1. One surface is a backlight surface, and the other surface is a light-receiving surface. It is understood that the terms "light-receiving surface" and "backlight surface" are relative; the light-receiving surface specifically refers to the surface on the substrate 111 in the solar cell 100 or photovoltaic module that is primarily exposed to sunlight. The light-receiving surface typically has a textured surface, which increases the light absorption area, improves the photocurrent, and helps to improve the efficiency of the cell.

[0151] The doped region 112 is located on one side of the substrate 111 along the first direction F1. The doped region 112 has a different conductivity type than the dopant element in the substrate 111, allowing them to form a PN junction structure together. For example, when the substrate 111 is an N-type silicon substrate, the doped region 112 can be a P-type emitter. As another example, when the substrate 111 is a P-type silicon substrate, the doped region 112 can be an N-type emitter.

[0152] For example, the doped region 112 can be formed by diffusing a dopant element into the substrate 111 on one side of the substrate 111 surface. When the substrate 111 is an N-type substrate, a P-type doped region 112 can be formed by boron diffusion into the substrate 111. Of course, the doped region 112 can also be a doped layer, and there is no specific limitation here.

[0153] The tunneling layer 113 is located on the other side of the substrate 111 along the first direction F1. The tunneling layer 113 is used to achieve interface passivation of the surface of the substrate 111, providing a chemical passivation effect. For example, by saturating the dangling bonds on the surface of the substrate 111 on the other side of the first direction F1, the density of interface defect states is reduced, thereby reducing the recombination centers on the other side of the substrate 111 along the first direction F1 and lowering the carrier recombination rate. The tunneling layer 113 can be made of a dielectric material. For example, the material of the tunneling layer 113 can be at least one of silicon oxide, magnesium fluoride, silicon oxide, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, or titanium oxide. In this embodiment, the tunneling layer 113 can be formed using low-pressure chemical vapor deposition (LPCVD). Of course, other processes such as thermal oxidation, plasma oxidation, or nitric acid oxidation can also be used to fabricate the tunneling layer 113; no specific limitations are imposed here.

[0154] A doped semiconductor layer 114 is disposed on the side of the tunneling layer 113 facing away from the substrate 111. The dopant element of the doped semiconductor layer 114 is adapted to the conductivity type of the dopant element of the substrate 111. For example, if the substrate 111 is an N-type substrate, the dopant element of the substrate 111 can be phosphorus and / or antimony. The dopant element of the doped semiconductor layer 114 is phosphorus. As another example, if the substrate 111 is a P-type substrate, the dopant element of the doped semiconductor layer 114 is boron. In the embodiments of this application, the doped semiconductor layer 114 is formed by doping amorphous silicon, microcrystalline silicon, polycrystalline silicon, etc. with an N-type dopant element. Exemplarily, the doped semiconductor layer 114 is a phosphorus-doped polycrystalline silicon layer. In this case, the stacked tunneling layer 113 and the doped semiconductor layer 114 together form a passivation contact structure, which provides good surface passivation for the other side of the substrate 111 along the first direction F1.

[0155] Passivation layers 120 can be provided on the side of the doped region 112 away from the substrate 111 and on the side of the doped semiconductor layer 114 away from the tunneling layer 113, without any specific restrictions.

[0156] For example, with Figure 5For example, both sides of the solar cell substrate 110a are target surfaces. The seed layer 131 on the first surface m1 side is in contact with the doped region 112, and the seed layer 131 on the second surface m2 side is in contact with the doped semiconductor layer 114.

[0157] According to some embodiments of this application, please refer to Figure 6 , Figure 6 This is a partial cross-sectional view of a solar cell 100b in some embodiments of this application. The solar cell substrate 110b includes a substrate 111 and functional layers located on both sides of the substrate 111 along a first direction F1. One of the functional layers includes a first tunneling layer 113a and a first doped semiconductor layer 114a stacked on the substrate 111, and the other functional layer includes a second tunneling layer 113b and a second doped semiconductor layer 114b stacked on the substrate 111.

[0158] The first tunneling layer 113a and the second tunneling layer 113b can be understood with reference to tunneling layer 113, and will not be described again. The first doped semiconductor layer 114a and the second doped semiconductor layer 114b can be understood with reference to doped semiconductor layer 114, and will not be described again. The first doped semiconductor layer 114a and the second doped semiconductor layer 114b have different doping types.

[0159] For example, with Figure 6 For example, both sides of the solar cell substrate 110b are target surfaces. The seed layer 131 and the second doped semiconductor layer 114b are in contact on the first surface m1 side, and the seed layer 131 and the first doped semiconductor layer 114a are in contact on the second surface m2 side.

[0160] Therefore, through the above embodiments, by configuring different solar cell substrates, the solar cells can be single-sided or double-sided TOPCon (Tunnel Oxide Passivated Contact) cells.

[0161] According to some embodiments of this application, please refer to Figure 7 , Figure 7 This is a flowchart illustrating a method for manufacturing a solar cell according to some embodiments of this application. Embodiments of this application provide a method for manufacturing a solar cell, including:

[0162] Step S110: Provide a solar cell intermediate; the solar cell intermediate includes a solar cell substrate and a passivation layer, the solar cell substrate has a first surface and a second surface disposed opposite to each other along a first direction, at least one of the first surface and the second surface is a target surface, the target surface includes a first region and a second region, and the passivation layer is disposed on the target surface;

[0163] Step S120: A seed layer in contact with the solar cell substrate is formed on the first region; the distribution density of the seed layer in a unit area of ​​the first region is positively correlated with the sheet resistance of a unit area of ​​the first region.

[0164] Step S130: A metal layer in contact with the seed layer is formed on the side of the passivation layer away from the solar cell substrate to form an electrode and obtain a solar cell; the orthogonal projection of the metal layer on the target surface is located in the first region, and the orthogonal projection area of ​​the seed layer on the target surface is smaller than the orthogonal projection area of ​​the metal layer on the target surface.

[0165] The advantages of the solar cells produced by the method of manufacturing solar cells can be seen in the solar cells illustrated in some of the foregoing embodiments, and will not be repeated here.

[0166] According to some embodiments of this application, please refer to Figure 8 , Figure 8 This is a flowchart illustrating step S120 in some embodiments of this application. Forming a seed layer in contact with the solar cell substrate in the first region (i.e., step S120) includes:

[0167] Step S121: Print an initial seed layer on the side of the passivation layer away from the solar cell substrate using a screen printing process; the orthographic projection of the initial seed layer on the target surface is located in the first region; the distribution density of the initial seed layer on the target surface within a unit area of ​​the first region is positively correlated with the sheet resistance of the unit area of ​​the first region.

[0168] Step S122: The initial seed layer is sintered to form a seed layer in contact with the solar cell substrate.

[0169] Thus, the seed layer can be produced using screen printing and sintering processes, facilitating manufacturing. For example, the initial seed layer paste can be silver paste, and the metal layer paste can be silver-coated copper paste.

[0170] According to some embodiments of this application, please refer to Figure 9 , Figure 9 The flowchart of step S122 in some embodiments of this application is shown. The initial seed layer includes multiple independent initial seed units. Sintering the initial seed layer to form a seed layer in contact with the solar cell substrate (i.e., step S122) includes:

[0171] Step S1221: Sinter multiple initial seed units to form multiple seed units in contact with the solar cell substrate; the multiple seed units correspond one-to-one with the multiple initial seed units, and the multiple seed units constitute a seed layer.

[0172] The advantages of setting seed units can be seen in the advantages illustrated in some of the foregoing embodiments, and will not be repeated here.

[0173] According to some embodiments of this application, the process for forming the metal layer includes a metallization heat treatment process or an electroplating process.

[0174] Thus, the process for forming the metal layer can be flexibly chosen, without specific restrictions.

[0175] According to some embodiments of this application, please refer to Figure 10 , Figure 10 This is a schematic diagram of the structure of a photovoltaic module 10 in some embodiments of this application. The embodiments of this application provide a photovoltaic module 10, including a battery string 11, an encapsulation layer 12, and a cover plate 13. The encapsulation layer 12 covers the surface of the battery string 11, and the cover plate 13 covers the surface of the encapsulation layer 12 away from the battery string 11. The battery string 11 is formed by connecting multiple solar cells as described in any of the above embodiments; or, the battery string 11 is formed by connecting multiple solar cells manufactured using the same method as described in any of the above embodiments.

[0176] Furthermore, the solar cells are electrically connected in whole or in multiple segments to form multiple cell strings 11, and the multiple cell strings 11 are electrically connected in series and / or in parallel.

[0177] In some embodiments, multiple cell strings 11 can be electrically connected via conductive strips 14. An encapsulation layer 12 covers both the front and back sides of the solar cell.

[0178] In some embodiments, the encapsulation layer 12 may be an organic encapsulation film such as ethylene-vinyl acetate copolymer (EVA) film, polyethylene octene coelastomer (POE) film, or polyethylene terephthalate (PET) film.

[0179] In some embodiments, the cover plate 13 can be a glass cover plate, a plastic cover plate, or other cover plate with light transmission function.

[0180] In some embodiments, the surface of the cover plate 13 facing the encapsulation layer 12 can be an uneven surface, thereby increasing the utilization rate of incident light.

[0181] The photovoltaic module 10 also possesses the advantages of the solar cells mentioned above, so they will not be repeated here.

[0182] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0183] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A solar cell, characterized in that, include: A solar cell substrate has a first surface and a second surface disposed opposite to each other along a first direction, wherein at least one of the first surface and the second surface is a target surface, and the target surface includes a first region and a second region. A passivation layer is provided on the target surface; and An electrode is located in the first region; the electrode includes a stacked seed layer and a metal layer, the seed layer being in contact with the solar cell substrate; Wherein, the projected area of ​​the seed layer on the solar cell substrate is smaller than the projected area of ​​the metal layer on the solar cell substrate; The distribution density of the seed layer within a unit area of ​​the first region is positively correlated with the sheet resistance within a unit area of ​​the first region.

2. The solar cell according to claim 1, characterized in that, The distribution density of the seed layer within a unit area of ​​the first region decreases continuously as the sheet resistance of the unit area of ​​the first region decreases.

3. The solar cell according to claim 1, characterized in that, The sheet resistance per unit area in the first region shows a negative correlation with the distribution distance. The distribution distance is the distance between a unit area region on the first region and the center of the target surface.

4. The solar cell according to claim 3, characterized in that, The sheet resistance per unit area in the first region decreases continuously as the distribution distance increases.

5. The solar cell according to any one of claims 1-4, characterized in that, The seed layer comprises multiple independent seed units.

6. The solar cell according to claim 5, characterized in that, The first region and the second region are alternately arranged along the second direction. Multiple first regions are provided and the first region extends along a third direction. The first direction, the second direction and the third direction intersect each other. The first region is provided with multiple independent seed units; Along the direction from the center of the first region to the edge of the first region, the spacing between two adjacent seed units in the third direction shows an increasing trend.

7. The solar cell according to claim 6, characterized in that, Within the same first region, the spacing between two adjacent seed units increases sequentially along the direction from the center of the first region to the edge of the first region.

8. The solar cell according to claim 6, characterized in that, The spacing between two adjacent seed units along the third direction is a preset spacing, and the minimum preset spacing among all the preset spacings corresponding to the seed units in the first region is the minimum preset spacing. Along the third direction, the first region located at the center of the first surface is the middle first region, and the first region located at the edge of the first surface is the edge first region; The minimum preset spacing increases along the direction from the middle first region to the edge first region.

9. The solar cell according to claim 8, characterized in that, The minimum preset spacing increases sequentially along the direction from the middle first region to the edge first region.

10. The solar cell according to claim 5, characterized in that, All the seed units have the same projected area and shape on the target surface; and / or The projected area S of the seed unit on the target surface satisfies: 78.5 μm. 2 ≤S≤2826μm 2 ; and / or The maximum extension dimension L of the orthographic projection of the seed unit on the target surface satisfies: 10μm≤L≤60μm.

11. The solar cell according to any one of claims 1-4, characterized in that, The solar cell substrate includes a substrate and functional layers located on both sides of the substrate along the first direction; One of the functional layers includes a doped region disposed on the substrate, and the other functional layer includes a tunneling layer and a doped semiconductor layer stacked on the substrate; or One of the functional layers includes a first tunneling layer and a first doped semiconductor layer stacked on the substrate, and the other functional layer includes a second tunneling layer and a second doped semiconductor layer stacked on the substrate.

12. A method for manufacturing a solar cell, characterized in that, include: Provide solar cell intermediates; The solar cell intermediate includes a solar cell substrate and a passivation layer. The solar cell substrate has a first surface and a second surface disposed opposite to each other along a first direction. At least one of the first surface and the second surface is a target surface. The target surface includes a first region and a second region. The passivation layer is disposed on the target surface. A seed layer is formed on the first region to contact the solar cell substrate; The distribution density of the seed layer in a unit area of ​​the first region is positively correlated with the sheet resistance of a unit area of ​​the first region. A metal layer in contact with the seed layer is formed on the side of the passivation layer opposite to the solar cell substrate to form an electrode, thereby obtaining a solar cell; The orthographic projection of the metal layer on the target surface is located within the first region, and the orthographic projection area of ​​the seed layer on the target surface is smaller than the orthographic projection area of ​​the metal layer on the target surface.

13. The method for manufacturing a solar cell according to claim 12, characterized in that, The process of forming a seed layer in contact with the solar cell substrate on the first region includes: An initial seed layer is printed on the side of the passivation layer opposite to the solar cell substrate using a screen printing process; the orthographic projection of the initial seed layer on the target surface is located within the first region; the distribution density of the orthographic projection of the initial seed layer on the target surface within a unit area of ​​the first region is positively correlated with the sheet resistance of a unit area of ​​the first region. The initial seed layer is sintered to form a seed layer in contact with the solar cell substrate.

14. The method for manufacturing a solar cell according to claim 13, characterized in that, The initial seed layer comprises multiple independent initial seed units; The sintering process of the initial seed layer to form a seed layer in contact with the solar cell substrate includes: The plurality of initial seed units are sintered to form a plurality of seed units in contact with the solar cell substrate; the plurality of seed units correspond one-to-one with the plurality of initial seed units, and the plurality of seed units constitute the seed layer.

15. A photovoltaic module, characterized in that, include: Battery string; An encapsulation layer is used to cover the surface of the battery string; and A cover plate, the cover plate being used to cover the surface of the encapsulation layer away from the battery string; The battery string is formed by connecting multiple solar cells as described in any one of claims 1-11; or, the battery string is formed by connecting multiple solar cells manufactured by the method of manufacturing solar cells as described in any one of claims 12-14.

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