Solar cells and photovoltaic modules

Abstract

This invention provides a solar cell and a photovoltaic module, belonging to the field of semiconductor technology. The solar cell includes a semiconductor substrate, which includes opposing first and second surfaces; and a plurality of first current collector electrodes disposed on the first surface of the semiconductor substrate. The plurality of first current collector electrodes extend along a first direction and are spaced apart along a second direction. Each first current collector electrode includes a plurality of first contact portions and a first transmission portion. The plurality of first contact portions are spaced apart along the first direction. The first transmission portion is disposed on the side of the first contact portion away from the semiconductor substrate and is in contact with and connected to the plurality of first contact portions, extending along the first direction. In at least one pair of adjacent first current collector electrodes, the spacing between at least one pair of adjacent first contact portions in the first direction is less than or equal to the spacing between the pair of adjacent first current collector electrodes in the second direction.

Description

Technical Field

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

[0002] Currently, in the fabrication process of solar cells, high-temperature paste is usually printed on the passivation layer first, or electrodes are formed by laser grooving combined with electroplating (or vapor deposition), and then sintering is performed so that the high-temperature paste or electroplating material burns through the passivation layer and comes into contact with the doped conductive layer.

[0003] Current electrode fabrication processes require the use of large amounts of high-temperature paste or electroplating materials to form the electrode, ensuring it penetrates the passivation layer and achieves good contact with the doped conductive layer, resulting in high battery costs. Furthermore, because the entire electrode burns through the passivation layer to contact the doped conductive layer, the passivation effect is poor. Therefore, a solution is needed that balances electrode contact performance, fabrication cost, and passivation performance. Summary of the Invention

[0004] In view of the above, in order to at least partially solve at least one of the aforementioned technical problems, the present invention provides a solar cell and a photovoltaic module.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] According to one embodiment of the present invention, a solar cell is provided, comprising:

[0007] A semiconductor substrate, the semiconductor substrate including opposing first and second surfaces;

[0008] In addition, a plurality of first collector electrodes are disposed on a first surface of a semiconductor substrate, the plurality of first collector electrodes extending along a first direction and spaced apart along a second direction; the first collector electrode includes a plurality of first contact portions and a first transmission portion, the plurality of first contact portions being spaced apart along the first direction; the first transmission portion is disposed on the side of the first contact portion away from the semiconductor substrate and is in contact with the plurality of first contact portions, the first transmission portion extending along the first direction;

[0009] In this configuration, among at least one pair of adjacent first collector electrodes, the spacing between at least one pair of adjacent first contacts in the first direction is less than or equal to the spacing between the pair of adjacent first collector electrodes in the second direction.

[0010] According to another aspect of the present invention, a photovoltaic module is provided, comprising: a plurality of the above-described solar cells connected to form a solar cell string; and an encapsulation layer covering the surface of the plurality of solar cells.

[0011] According to the solar cell provided in the above embodiments of the present invention, by configuring the first current collector electrode as including a plurality of discontinuously distributed contact portions and a transmission portion connected to the plurality of contact portions, wherein the contact portions can be made of high-temperature paste, the amount of high-temperature paste used to fabricate the contact portions can be saved while ensuring contact performance, thereby reducing the cost of electrode fabrication and thus reducing the cost of the battery. Simultaneously, the discontinuous distribution of the plurality of contact portions can reduce damage to the passivation layer and the doped conductive layer, thus improving passivation performance. Furthermore, in at least one pair of adjacent first current collector electrodes, by setting the spacing between adjacent first contact portions to be smaller than the spacing between adjacent first current collector electrodes in the second direction, electrode paste can be saved while maintaining the electrode carrier collection effect. Attached Figure Description

[0012] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0013] Figure 1 A top view schematic diagram of a solar cell provided in an embodiment of the present invention;

[0014] Figure 2 for Figure 1 A schematic cross-sectional view along line A1-A2;

[0015] Figure 3 A side view of a solar cell provided in an embodiment of the present invention;

[0016] Figure 4 A side view schematic diagram of a solar cell provided according to another embodiment of the present invention;

[0017] Figure 5 A top view of the first collector electrode and the second collector electrode provided in an embodiment of the present invention;

[0018] Figures 6A-6B SEM images of the cross-sections of the first contact portion and the first transmission portion provided in the embodiments of the present invention;

[0019] Figure 7 A top view schematic diagram of a solar cell provided in an embodiment of the present invention;

[0020] Figure 8 A top view schematic diagram of a solar cell provided in another embodiment of the present invention;

[0021] Figure 9 This is a top view of the first current collector electrode and the first welding point provided in an embodiment of the present invention;

[0022] Figure 10A top view schematic diagram of a solar cell provided in another embodiment of the present invention;

[0023] Figure 11 A top view schematic diagram of the first collector electrode provided in an embodiment of the present invention;

[0024] Figure 12 A top view schematic diagram of the first collector electrode provided in another embodiment of the present invention.

[0025] Explanation of reference numerals in the attached figures:

[0026] 10: Semiconductor substrate; 21: First doped conductive layer; 22: Second doped conductive layer; 30: Passivation layer; 31: First passivation layer; 32: Second passivation layer; 41: First collector electrode; 411: First contact portion; 412: First transmission portion; 413: Third contact portion; 42: Second collector electrode; 421: Second contact portion; 422: Second transmission portion; 43: First bus; 431: First bus electrode; 432: First solder joint; 433: First terminal line; 44: Second bus; 442: Second solder joint; 411a: First metal particle; 411b: First organic material; 411c: Metal silicide particle; 412a: Second metal spherical particle; 412b: Second metal sheet particle; 50: Tunneling layer; 51: First tunneling layer; 52: Second tunneling layer; 60: Anti-reflection layer; B: End. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0028] In the following detailed description, numerous specific details are set forth for ease of explanation to provide a full understanding of embodiments of the invention. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the invention.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0030] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). When using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0031] In this invention, the relative position between two components (e.g., a membrane or region), referred to as "above," "over," or "above," can mean that the two components are in direct contact or that they are not in direct contact. Similarly, the relative position between two components, referred to as "below," "under," or "below," can mean that the two components are in direct contact or that they are not in direct contact. For example, when one component (e.g., a membrane or region) is referred to as "on another component," it can be directly on the other component, or there may be other components between them. On the other hand, when a component is referred to as "directly on another component," there are no components between them. Furthermore, when one component is referred to as "on another component," the two have a vertical relationship in the planar view, and this component can be above or below the other component, thus this vertical relationship depends on the orientation of the device.

[0032] In related technologies, the fabrication process of solar cells typically involves first printing a high-temperature paste onto a passivation layer to form electrodes, followed by sintering to allow the high-temperature paste to penetrate the passivation layer and contact the doped conductive layer. Current electrode fabrication processes require a large amount of high-temperature paste to form the electrodes, ensuring they penetrate the passivation layer and achieve good contact with the doped conductive layer, resulting in high cell costs. Furthermore, because the entire electrode burns through the passivation layer to contact the doped conductive layer, the passivation effect is poor. Therefore, a solution is needed that balances electrode contact performance, manufacturing cost, and passivation performance.

[0033] In realizing the concept of this invention, it was discovered that by configuring the electrode to include multiple discontinuously distributed contact portions and a transmission portion connected to these contact portions, the contact portions can be made of high-temperature paste or electroplating material. Since the discontinuous distribution of the multiple contact portions ensures contact performance, the amount of high-temperature paste or electroplating material used to fabricate the contact portions can be reduced. Furthermore, the transmission portion can be made of base metal paste, thereby reducing the cost of electrode fabrication. However, in the extension direction of the current collector electrode, excessively large spacing between adjacent contact portions is detrimental to carrier collection, while excessively small spacing leads to large-area burn-through of the passivation layer, making it prone to passivation damage and hindering the passivation effect.

[0034] In view of this, the present invention proposes a solar cell and a photovoltaic module that improves cell efficiency by balancing the length of the contact portion along the extension direction of the current collector electrode with the spacing between adjacent contact portions.

[0035] Figure 1 This is a top view schematic diagram of a solar cell provided in an embodiment of the present invention.

[0036] Figure 2 for Figure 1 A schematic diagram of the cross section along line A1-A2.

[0037] According to one embodiment of the present invention, a solar cell is provided, with reference to... Figure 1 , Figure 2 As shown, it includes a semiconductor substrate 10 and a plurality of first collector electrodes 41, wherein:

[0038] A plurality of first collector electrodes 41 are disposed on a first surface 10a of a semiconductor substrate 10. The plurality of first collector electrodes 41 extend along a first direction X and are spaced apart along a second direction Y. Each first collector electrode 41 includes a plurality of first contact portions 411 and a first transmission portion 412. The plurality of first contact portions 411 are spaced apart along the first direction X. The first transmission portion 412 is disposed on the side of the first contact portion 411 away from the semiconductor substrate 10 and is in contact with the plurality of first contact portions 411. The first transmission portion 412 extends along the first direction X. The first direction X and the second direction Y intersect.

[0039] In some embodiments, in at least one pair of adjacent first collector electrodes 41, the distance R2 between at least one pair of adjacent first contact portions 411 in the first direction X is less than or equal to the distance P between the pair of adjacent first collector electrodes 41 in the second direction Y.

[0040] According to an embodiment of the present invention, the spacing P between adjacent first collector electrodes 41 in the second direction Y balances the material usage of the first collector electrodes 41 and the carrier collection distance in the second direction Y. If the spacing P is too small, the material usage of the first collector electrodes 41 will be excessive, and light shading will be severe. If the spacing P is too large, the carrier collection distance will be large, which is not conducive to the carrier collection efficiency and will cause severe internal carrier recombination. Therefore, the spacing P that can be designed is often different when the material, band structure, doping concentration, etc. of the first doped conductive layer are different. After the spacing P of the first collector electrodes 41 is optimized and determined, the spacing R2 between the first contacts in the first direction X depends on the setting of the spacing P of the first collector electrodes 41. In order to ensure that the first contacts collect carriers along the first direction, the spacing R2 needs to be set to be less than or equal to the spacing P. If the spacing R2 is too large, it will hinder carrier collection between two adjacent first contact portions; if the spacing R2 is too small, while the improvement in carrier collection efficiency will be limited, it will also lead to excessive use of first contact portions, resulting in unnecessary material consumption. Furthermore, since a large proportion of the length of the first contact portion will cause greater damage to the passivation layer and the doped conductive layer, it will reduce the passivation effect of the passivation layer. Therefore, the spacing R2 is set to be less than or equal to the spacing P. Moreover, in order to collect and extract the collected carriers more quickly, it is preferable that the spacing R2 is less than the spacing P.

[0041] In some embodiments, in at least one pair of adjacent first collector electrodes 41, the ratio of the distance R2 between the at least one pair of adjacent first contact portions 411 in the first direction X and the distance P between the pair of adjacent first collector electrodes 41 in the second direction Y is less than or equal to 0.8. The ratio can be, for example, 0.2, 0.4, 0.5, or 0.8, but is not limited to these values. The first collector electrode 41 collects current in the second direction Y; its first transmission portion 412 mainly performs transmission, while the first contact portion 411 mainly collects charge carriers from the semiconductor layer. Thus, by further controlling the ratio of distance R2 / distance P, it is ensured that the first contact portion can withstand a larger current or collect more charge carriers.

[0042] It should be noted that the distance P between adjacent first collector electrodes 41 in the second direction Y can be expressed as the distance between the center lines of adjacent first collector electrodes 41 extending along the first direction X. The distance R2 between adjacent first contact portions 411 in the first direction is the distance between two relatively close edges of adjacent first contact portions 411.

[0043] The distance P between adjacent first collector electrodes 41, or the distance R2 between adjacent first contact portions 411, can be measured using a scanning electron microscope (SEM) or a ruler. For example, a top view of the first collector electrode can be obtained first, and the center line of the first collector electrode can be extracted using image processing algorithms or visual inspection. The distance P between the center lines of adjacent first collector electrodes can then be measured. Alternatively, based on the height difference between the area with the first contact portion and other areas on the first collector electrode, and the obvious brightness difference in the image, the distance between two relatively close edges of the first contact portions can be directly measured on the image.

[0044] It is understood that the aforementioned "at least one pair of adjacent first collector electrodes 41" can be a pair of adjacent first collector electrodes or multiple pairs of adjacent first collector electrodes. In the case of multiple pairs of adjacent first collector electrodes, it can be some or all of the adjacent first collector electrodes. Similarly, the aforementioned "at least one pair of adjacent second collector electrodes 42" is also like this, and will not be elaborated further. Unless otherwise specified, "at least one first collector electrode 41" and "at least one second collector electrode 42" mentioned below refer to the aforementioned meanings.

[0045] According to some embodiments of the present invention, the plurality of first contact portions 411 included by each of the plurality of first current collector electrodes 41 are regularly arranged on at least a portion of the passivation layer 30, and the plurality of second contact portions 421 included by each of the plurality of second current collector electrodes 42 are regularly arranged on at least a portion of the passivation layer 30. It is understood that "regular arrangement" refers to one or more first contact portions 411, and the spacing between one or more adjacent first contact portions 411, forming a repeating unit, which is repeated according to the same pattern. For example, for each first current collector electrode 41, the plurality of first contact portions 411 may be spaced apart in a first direction with the same spacing. In this case, the lengths of the plurality of first contact portions 411 along the first direction may be equal or periodically varied, for example, alternating between a first length and a second length. Alternatively, "regular arrangement" may also mean, for example, for each first current collector electrode 41, the plurality of first contact portions 411 have the same length along the first direction and are spaced apart in the first direction with periodically varying spacing. The same applies to a second current collector electrode 42, and will not be elaborated further. Unless otherwise specified, "regular arrangement" as used below refers to the foregoing meaning.

[0046] According to embodiments of the present invention, the semiconductor substrate 10 can be an N-type, P-type, or intrinsic crystalline silicon substrate, such as a semiconductor material selected from monocrystalline silicon, polycrystalline silicon, and microcrystalline silicon. It can also be an N-type or P-type monocrystalline silicon substrate, where the cell conversion efficiency is higher than that of other types, such as polycrystalline silicon cells. An N-type crystalline silicon substrate is obtained by introducing donor impurities such as group VA elements like phosphorus (P), arsenic (As), or antimony (Sb) into these semiconductor materials, or a P-type crystalline silicon substrate is obtained by introducing acceptor impurities such as group IIIA elements like boron (B), aluminum (Al), or gallium (Ga).

[0047] According to an embodiment of the present invention, the first surface 10a of the semiconductor substrate 10 can be either the front or the back of the battery, without limitation. Generally, the front of the battery serves as the light-receiving surface and the back as the back-lighting surface, or it can be light-receiving on both sides, in which case both the front and the back serve as light-receiving surfaces.

[0048] According to embodiments of the present invention, by configuring the first current collector electrode as comprising a plurality of discontinuously distributed contact portions and a transmission portion connected to the plurality of contact portions, wherein the contact portions can be made of high-temperature slurry, or by laser grooving combined with electroplating or vapor deposition, the discontinuous distribution of the plurality of contact portions can save material used to fabricate the contact portions while ensuring contact performance, thereby reducing the cost of electrode fabrication and thus reducing battery cost. Furthermore, in at least one pair of adjacent first current collector electrodes, by setting the spacing between adjacent first contact portions to be smaller than the spacing between adjacent first current collector electrodes in the second direction, electrode slurry can be saved while maintaining electrode carrier collection performance.

[0049] In an embodiment of the present invention, the solar cell further includes: a first doped conductive layer 21 disposed on a first surface 10a of a semiconductor substrate 10; a passivation layer 30 disposed on the side of the first doped conductive layer 21 away from the semiconductor substrate 10; wherein a plurality of first current collector electrodes 41 are disposed on the side of the passivation layer away from the first doped conductive layer 21; a plurality of first contact portions 411 pass through the passivation layer and are electrically connected to the first doped conductive layer 21; the conductivity type of the first doped conductive layer 21 is the same as the conductivity type of the semiconductor substrate 10.

[0050] According to an embodiment of the present invention, since the conductivity type of the first doped conductive layer 21 is the same as that of the semiconductor substrate 10, the first doped conductive layer 21 transmits majority carriers. The spacing R2 between adjacent first contact portions 411 in the first collector electrode 41 in the first direction X can be appropriately enlarged to ensure the collection effect of majority carriers. At the same time, the amount of electrode material used can be reduced and the damage to the passivation layer 30 can be reduced. However, the requirement that the spacing R2 should be less than or equal to the spacing P should still be met, otherwise it will be detrimental to the collection and transmission of majority carriers.

[0051] According to an embodiment of the present invention, the first doped conductive layer 21 may be a semiconductor material, which may be one of monocrystalline silicon, polycrystalline silicon, or microcrystalline silicon. It may be formed by in-situ doping in the semiconductor substrate 10, or by additional deposition (e.g., ALD, CVD, etc.). When it is an additionally deposited layer, an interface layer may also be present between the first doped conductive layer 21 and the semiconductor substrate 10, such as intrinsic amorphous silicon (corresponding to a heterojunction passivation structure) or an oxide layer (e.g., silicon oxide, corresponding to a TOPCon passivation structure).

[0052] According to embodiments of the present invention, the passivation layer 30 can be an interface passivation layer, an anti-reflection layer, or a stacked interface passivation layer and an anti-reflection layer, which can protect and passivate the semiconductor substrate 10 or other functional layers such as the first doped conductive layer 21 located below the passivation layer 30. Exemplarily, the passivation layer 30 can be a single-layer film formed from one of the following materials: silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, silicon carbide, and amorphous silicon, or a stacked film composed of one or more materials. For example, an aluminum oxide passivation layer can be prepared first using, for example, ALD (atomic layer deposition), and then one or more silicon nitride layers can be formed thereon using, for example, PECVD.

[0053] In some embodiments, the spacing P of the first collector electrode can be designed differently depending on the type of solar cell or the material, band structure, doping concentration, etc. of the first doped conductive layer. Generally, the spacing P of at least one pair of adjacent first collector electrodes 41 in the second direction Y is 0.5~1.5mm, for example, it can be 0.5mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.5mm, but is not limited to the values ​​listed. If the spacing P is too large, for example, greater than 1.5mm, the carrier collection distance between adjacent first collector electrodes is large, which easily causes internal carrier recombination and is not conducive to carrier collection; if the spacing P is too small, for example, less than 0.2mm, the first collector electrode will severely block light, which will reduce the light utilization rate and waste the material used to prepare the first collector electrode.

[0054] In some embodiments, the spacing P between different adjacent first collector electrodes 41 in the second direction Y may be the same or different.

[0055] In some embodiments, in at least one first current collector electrode 41, the spacing R2 between at least one pair of adjacent first contacts 411 in the first direction X is less than or equal to 1.5 mm. Extensive verification results have confirmed that when R2 exceeds 1.5 mm, it is related to the spacing P between adjacent first current collector electrodes 41, resulting in reduced battery power and hindering current collection. Further, the value of R2 is between 0.2 and 1.5 mm, for example, 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1 mm, and 1.5 mm, but not limited to these values. If R2 is less than 0.2, it will reduce the passivation effect of the passivation layer and cause unnecessary material waste; therefore, the preferred value range for R2 is 0.2-1.2 mm.

[0056] In some embodiments, the solar cell may be a bifacial contact cell, in which case the solar cell may further include a plurality of second current collectors 42 disposed on the second surface 10b, or the solar cell may be a back contact cell, in which case a plurality of second current collectors 42 are disposed on the first surface 10a and are alternately disposed with a plurality of first current collectors 41.

[0057] In some embodiments, the second collector electrode 42 may adopt a structure similar to the first collector electrode, with discontinuously distributed second contact portions. Specifically, a plurality of second collector electrodes 42 extend along a first direction X and are spaced apart along a second direction Y. The second collector electrode 42 includes a plurality of second contact portions 421 and a second transmission portion 422. The plurality of second contact portions 421 are spaced apart along the first direction X; the second transmission portion 422 is disposed on the side of the second contact portions 421 away from the semiconductor substrate 10 and is in contact with the plurality of second contact portions 421, and the second transmission portion 422 extends along the first direction X. This is advantageous in further saving the amount of high-temperature paste or electroplating material while ensuring the carrier collection effect. It is understood that this is not a limitation. In other embodiments, the second collector electrode 42 may also adopt a conventional electrode structure, that is, the second contact portions extend continuously and the second transmission portion 422 is an integral structure.

[0058] To further illustrate the specific applicable structures of the discontinuously distributed contact portions in the first current collector 41 and the second current collector 42 for different types of solar cells, we will first take a double-sided contact solar cell as an example. Figure 3 This is a side view of a solar cell provided in an embodiment of the present invention. Figure 3As shown, the solar cell further includes a second doped conductive layer 22 disposed on the second surface 10b of the semiconductor substrate 10. The second doped conductive layer 22 and the first doped conductive layer 21 are disposed opposite to each other, and the conductivity types of the second doped conductive layer 22 and the semiconductor substrate 10 are opposite. A passivation layer 30 is also disposed on the side of the second doped conductive layer 22 away from the semiconductor substrate 10. Specifically, it may include a first passivation layer 31 and a second passivation layer 32. The first passivation layer 31 is disposed on the side of the first doped conductive layer 21 away from the semiconductor substrate 10, and the second passivation layer 32 is also disposed on the side of the second doped conductive layer 22 away from the semiconductor substrate 10. A plurality of second current collectors 42 are disposed on the side of the second passivation layer 32 away from the second doped conductive layer 22, and a plurality of second contacts 421 of the second current collectors 42 pass through the second passivation layer 32 and are electrically connected to the second doped conductive layer 22.

[0059] At this time, the first surface 10a of the semiconductor substrate 10 can be either the front or the back of the battery, without limitation. Generally speaking, the front of the battery is the light-receiving surface and the back is the backlighting surface, or it can be light-receiving on both sides, in which case both the front and the back are light-receiving surfaces.

[0060] In embodiments of the present invention, the second doped conductive layer 22 may be a semiconductor material, which may be one of monocrystalline silicon, polycrystalline silicon, or microcrystalline silicon. It may be formed by in-situ doping in the semiconductor substrate 10, or by additional deposition (e.g., ALD, CVD, etc.). When it is an additionally deposited layer, there may also be an interface layer between the second doped conductive layer and the semiconductor substrate, such as intrinsic amorphous silicon (corresponding to a heterojunction passivation structure) or an oxide layer (e.g., silicon oxide, corresponding to a TOPCon passivation structure).

[0061] For example, taking a double-sided contact battery as a tunneling oxide passivation contact (TOPCon) battery, the semiconductor substrate 10 can be an N-type silicon substrate, the first doped conductive layer 21 can be an N-type doped polycrystalline silicon layer prepared on the second surface 10b by low-pressure chemical vapor deposition, and the second doped conductive layer 22 can be a P-type doped layer formed by boron diffusion doping in the first surface 10a of the semiconductor substrate 10.

[0062] At this time, the solar cell may also include a tunneling layer 50, located between the first doped conductive layer 21 and the semiconductor substrate 10, forming a tunneling passivation contact structure with the first doped conductive layer 21.

[0063] According to embodiments of the present invention, the passivation layer 30 can be an interface passivation layer, an anti-reflection layer, or a stacked interface passivation layer and an anti-reflection layer, which can protect and passivate the semiconductor substrate or other functional layers, such as the first doped conductive layer or the second doped conductive layer, located below the passivation layer 30. Exemplarily, the passivation layer 30 can be a single-layer film formed from one of the following materials: silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, silicon carbide, or amorphous silicon, or a stacked film composed of one or more materials. For example, an aluminum oxide passivation layer can be prepared first using, for example, ALD (atomic layer deposition), and then one or more silicon nitride layers can be formed thereon using, for example, PECVD.

[0064] Secondly, taking solar cells as an example of back-contact batteries, Figure 4 This is a side view schematic diagram of a solar cell provided according to another embodiment of the present invention. Figure 4 As shown, the main difference from the aforementioned double-sided contact solar cell is that the second doped conductive layer 22 and the first doped conductive layer 21 are alternately disposed on the first surface 10a; the passivation layer 30 is also disposed on the side of the second doped conductive layer 22 away from the semiconductor substrate 10. At this time, a plurality of second current collectors 42 are disposed on the side of the passivation layer 30 away from the second doped conductive layer 22, and a plurality of second contact portions 421 of the second current collectors 42 pass through the passivation layer 30 and are electrically connected to the second doped conductive layer 22.

[0065] In this case, the first surface 10a of the semiconductor substrate 10 can be the back side of the battery to reduce the shading of the first and second collector electrodes on the front side of the battery and improve light utilization. Similarly, the front side of the battery can be the light-receiving surface and the back side can be the backlighting surface, or it can be light-receiving on both sides, in which case both the front and back sides can be light-receiving surfaces.

[0066] According to embodiments of the present invention, optionally, the first surface 10a and / or the second surface 10b may have a textured or polished structure. The textured structure may include a combination of one or more structures such as pyramids or cones; for example, the textured structure may include multiple pyramids. The polished structure may include a combination of one or more structures such as frustums or truncated cones; for example, the polished surface may include multiple polygonal or arc-shaped bases. The selection can be made specifically according to the contact requirements of the first doped conductive layer and the second doped conductive layer, and is not specifically limited.

[0067] According to an embodiment of the present invention, since the first doped conductive layer 21 and the second doped conductive layer 22 have different conductivity types, their requirements for carrier collection are different. Specifically, when the conductivity types of the second doped conductive layer 22 and the semiconductor substrate 10 are opposite, the second doped conductive layer 22 transports minority carriers, which are prone to recombination during the transport process. Therefore, the spacing Q2 between adjacent second contact portions 421 in the first direction X in the corresponding second collector electrode should be appropriately reduced to quickly collect minority carriers and achieve a collection balance between majority carriers and minority carriers.

[0068] Therefore, the arrangement of the first contact portion 411 in the first collector electrode 41 and the second contact portion 421 in the second collector electrode 42 is differentiated. To facilitate understanding of this differentiated arrangement, Figure 5 This is a top view schematic diagram of the first and second collector electrodes provided in an embodiment of the present invention. Figure 5 As shown, in at least one first collector electrode 41, the spacing R2 between at least one pair of adjacent first contact portions 411 is greater than the spacing Q2 between at least one pair of adjacent second contact portions 421 in at least one second collector electrode 42. In some embodiments, the length Q1 of the second contact portion 421 along the first direction X can be greater than the length R1 of the first contact portion 411 along the first direction X. This arrangement is more conducive to the second collector electrode 42 quickly collecting minority carriers, thus balancing the collection effect with that of majority carriers.

[0069] In embodiments of the present invention, in at least one first collector electrode 41, the spacing R2 between at least one pair of adjacent first contact portions 411 is 0.3 to 1.5 mm, for example, it can be 0.3 mm, 0.5 mm, 0.6 mm, 0.8 mm, 0.9 mm, 1.2 mm, or 1.5 mm, and is not limited to the values ​​listed. This arrangement takes into account that when the first collector electrode 41 is used to collect majority carriers, its spacing R2 can be appropriately increased, but it still needs to be less than or equal to the spacing P between adjacent first collector electrodes 41. The spacing Q2 between at least one pair of adjacent second contact portions 421 is 0.2 to 1.2 mm, for example, it can be 0.2 mm, 0.5 mm, 0.8 mm, 0.9 mm, 1 mm, or 1.2 mm, but is not limited to the values ​​listed. This setting is based on the consideration that when the second collector electrode 42 is used to collect minority carriers, its spacing Q2 can be appropriately reduced. However, when it is less than 0.2, the improvement of minority carrier collection effect is limited, resulting in unnecessary consumption of electrode materials. Furthermore, due to the greater damage to the passivation layer 30, it is not conducive to improving the passivation performance.

[0070] In embodiments of the present invention, the length R1 of the first contact portion 411 in the first direction X also affects the carrier collection effect. Increasing the length is beneficial for rapid carrier collection; however, an excessively long length has limited effect on improving the carrier collection effect and increases unnecessary electrode material consumption. Therefore, the length R1 of the first contact portion 411 is 0.2~3mm, for example, R1 can be 0.2mm, 0.4mm, 0.6mm, 0.8mm, 1mm, 2mm, 3mm, but is not limited to the values ​​listed. Thus, by setting the length R1 of the first contact portion 411 within the above range, it is possible to balance the carrier collection effect and electrode manufacturing cost, and it can also be matched with the spacing between adjacent first contact portions 411 to uniformly collect carriers in the first direction X, avoiding excessive local current density and resulting in local hot spot effects.

[0071] In embodiments of the present invention, similarly, in the first direction X, the length Q1 of the second contact portion 421 is 0.2~3mm, for example, Q1 can be 0.2mm, 0.4mm, 0.6mm, 0.8mm, 1mm, 2mm, 3mm, but is not limited to the values ​​listed. Its effect is the same as that of the first contact portion 411, and will not be repeated here. In some embodiments, the length Q1 of the second contact portion 421 along the first direction X can be greater than the length R1 of the first contact portion 411 along the first direction X.

[0072] In an embodiment of the present invention, the first contact portion 411 in the first collector electrode 41 includes at least one of silver, nickel, titanium, and transparent conductive oxide (TCO). Examples of TCOs include indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), and tungsten-doped indium oxide (IWO). The material selection for the first contact portion 411 is based on the consideration of forming a good ohmic contact with the first doped conductive layer 21, thereby facilitating carrier collection, while preventing the diffusion of elements from the first transport portion 412 into the first doped conductive layer 21, which could adversely affect the first doped conductive layer 21 (for example, copper can damage the doped conductive layer).

[0073] In embodiments of the present invention, in the first current collector electrode 41, the first transmission portion 412 can be made of a base metal, including at least one of copper, aluminum, silver-clad copper, and silver-copper alloys. The material selection of the first transmission portion 412 is primarily based on its conductivity, which is used to transmit charge carriers from the first contact portion 411; therefore, a base metal material that is inexpensive and has good conductivity is preferred. Similarly, in the second current collector electrode 42, the range of possible materials for the second contact portion 421 is the same as that for the first contact portion 411, and the range of possible materials for the second transmission portion 422 is the same as that for the first transmission portion 412, so further details are omitted.

[0074] In an embodiment of the present invention, in at least one first collector electrode 41, the ratio of the length R1 of at least one first contact portion 411 along the first direction X to the spacing R2 between another first contact portion 411 adjacent to the first contact portion 411 is less than the ratio of the length Q1 of at least one second contact portion 421 along the first direction X to the spacing Q2 between another second contact portion 421 adjacent to the second contact portion 421 in at least one second collector electrode 42. Thus, by controlling the ratio of length to spacing, the influence of the length and spacing of the first contact portion 411 and the second contact portion 421 on the carrier collection effect can be comprehensively considered, thereby more effectively controlling the carrier collection on the first collector electrode 41 and the second collector electrode 42. Based on this, since the minority carrier lifetime is shorter than the majority carrier lifetime, by controlling the ratio of the length of the second contact portion of the second current collector electrode (the second doped conductive layer has the opposite conductivity type to the semiconductor substrate, and the second doped conductive layer is suitable for collecting minority carriers) along the first direction to a larger ratio of the distance between the second contact portion and the other contact portion adjacent to the second contact portion, minority carriers can be collected more effectively. This can achieve a balance in carrier collection between the first doped conductive layer and the second doped conductive layer, thereby improving battery efficiency.

[0075] In embodiments of the present invention, in at least one first collector electrode 41, the ratio of the length R1 of at least one first contact portion 411 along the first direction X to the distance R2 between another first contact portion 411 adjacent to the first contact portion 411, or in at least one second collector electrode 42, the ratio of the length Q1 of at least one second contact portion 421 along the first direction X to the distance Q2 between another second contact portion 421 adjacent to the second contact portion 421, is 0.3 to 3, for example, 0.3, 0.5, 1, 2, 3, but is not limited to the values ​​listed. Thus, by comprehensively considering the influence of the length and distance of the first contact portion 411 and the second contact portion 421 on the carrier collection effect, controlling the ratio of their length to distance within the above range can avoid unnecessary electrode material loss due to an excessively high length ratio, or poor carrier collection effect due to an excessively low length ratio.

[0076] At this time, the setting of the ratio of the length to the spacing of the two is in conjunction with the aforementioned specific length and spacing settings, which is conducive to the uniform arrangement of the first contact part and the second contact part in the first direction X, thereby controlling the current density at each position on the first collector electrode and the second collector electrode to be balanced and avoiding local overheating.

[0077] Figures 6A-6B SEM images of the cross-sections of the first contact portion and the first transmission portion provided in an embodiment of the present invention.

[0078] In an embodiment of the present invention, reference is made to... Figure 6A , Figure 6BAs shown, the first contact portion 411 includes: a plurality of first metal particles 411a stacked to form a honeycomb structure with a plurality of holes, and a first organic matter 411b distributed among the plurality of first metal particles 411a.

[0079] In an embodiment of the present invention, the first contact portion 411 may further include: a plurality of metal silicide particles 411c embedded in the first doped conductive layer 21, thereby forming an ohmic contact with the first doped conductive layer 21 and improving the carrier collection efficiency.

[0080] In an embodiment of the present invention, the first transmission unit 412 includes: a plurality of second metal spherical particles 412a and a plurality of second metal sheet particles 412b, wherein some of the second metal particles are dispersed in at least some of the pores of the honeycomb structure.

[0081] In some embodiments, the cross-sectional shape of the first transmission section 412 may be, for example, trapezoidal. A trapezoidal first transmission section is more conducive to metal welding, reducing the risk of short circuits caused by welding. The cross-sectional shape of the first transmission section 412 may also be, for example, elliptical. Compared to a trapezoidal first transmission section, an elliptical first transmission section 412 reflects less light from the sides, reducing light obstruction.

[0082] According to an embodiment of the present invention, the surface and edge of the first contact portion are generally irregularly stacked with uneven grains, and the line width is 12.6 μm on average (which varies depending on the printing screen specifications); the silver grains have a diameter of 1.1~1.8 μm and have a relatively regular hexagonal plate-like stacked morphology (which may also be regular spherical depending on the paste composition system).

[0083] According to an embodiment of the present invention, the overall height of the first contact portion is 0.5~8μm, the width is 9~25μm, and the aspect ratio is about 23% (which varies depending on the printing screen specifications). It has a honeycomb structure with a hole diameter of 0.5~1.5μm. The silver is stacked in hexagonal flakes, presenting a distinct layered structure (which may also be regular spherical depending on the composition of the paste). There are some organic residues between the silver grains and at the silver-silicon contact surface (the contact surface between the first contact portion and the first doped conductive layer), which to some extent increases the pull-out force.

[0084] Figure 7 This is a top view schematic diagram of a solar cell provided in an embodiment of the present invention.

[0085] Figure 8 This is a top view schematic diagram of a solar cell provided in another embodiment of the present invention.

[0086] Figure 9 This is a top view of the first current collector electrode and the first welding point provided in an embodiment of the present invention.

[0087] In an embodiment of the present invention, the solar cell further includes a plurality of first busbars 43 disposed on the side of the passivation layer 30 away from the semiconductor substrate 10. The plurality of first busbars 43 are arranged at intervals along a first direction X and each extends along a second direction Y. The first busbars 43 are electrically connected to the first current collector 41.

[0088] In some embodiments, reference Figure 7 As shown, the solar cell is a bifacial solar cell. The bifacial solar cell also includes multiple second busbars, which are disposed on a surface opposite to the first busbars. The bifacial solar cell can have a main grid structure, a main gridless structure, or a partially main gridless structure.

[0089] In some embodiments, the first busbar 43 of the bifacial solar cell without a main grid structure includes a first solder joint 432. Further, at least a portion of the first busbar 43 may also include two sets of first terminal lines disposed opposite each other (only one set of first terminal lines is shown in the figure), with the first solder joint 432 located between the two sets of first terminal lines.

[0090] In some embodiments, reference Figure 7 As shown, at least part of the first busbar 43 may also include a first busbar electrode 431 (with a main grid structure) that extends continuously along the second direction, and the first welding point 432 is electrically connected to the first busbar electrode 431.

[0091] like Figure 7 The diagram shows a combination of a main gate structure and a main gateless structure, but it is not limited to this. It can also be that multiple first busbars 43 are all main gate structures or all are main gateless structures.

[0092] In some embodiments, reference Figure 8 As shown, the solar cell is a back-contact solar cell. Back-contact solar cells can have a main grid structure, a no-main-grid structure, or a partially no-main-grid structure.

[0093] In some embodiments, the first busbar 43 of the back-contact solar cell without a main grid structure includes a first solder joint 432. Further, it may also include two sets of first end lines 433 disposed opposite each other, with the first solder joint 432 located between the first end lines 433.

[0094] In some embodiments, reference Figure 8 As shown, the first bus 43 can also be replaced with a first bus electrode (with a main grid structure) that extends continuously along the second direction.

[0095] In some embodiments, reference Figure 8 As shown, one of the first collector electrode 41 and the second collector electrode 42 is in a discontinuous state.

[0096] In some embodiments, the first collector electrode 41 and the second collector electrode 42 are both continuous. The first bus electrode 431 of the back-contact solar cell with a main grid structure is connected to one of the first collector electrode 41 and the second collector electrode 42, and an insulating block is disposed between them.

[0097] Among them, reference Figure 7 , Figure 8 , Figure 9 As shown, the first busbar 43 includes a plurality of first welding points 432 spaced apart along the second direction Y. At the connection point of at least one first current collector electrode 41 with the first welding point 432, the length W3 of the first welding point 432 along the first direction X is greater than the distance R2 between adjacent first contact portions 411. This arrangement results in a first contact portion below the first welding point, thereby improving the surface roughness of the first welding point and increasing the contact area between the first welding point and the busbar structure (e.g., solder strip, electrical connection wire, or other busbar structure), thus improving the welding tensile strength and connection reliability of the busbar structure.

[0098] According to embodiments of the present invention, the plurality of first contact portions 411 included in each of the plurality of first current collector electrodes 41 can be arranged in a regular manner on the passivation layer 30. For example, the lengths of the plurality of first contact portions 411 are all equal, and the spacing between adjacent first contact portions 411 is all equal, thereby enabling relatively uniform collection of charge carriers at different locations of the solar cell. However, this is not a limitation. Considering the different factors such as charge carrier collection, mechanical stress, and passivation effect at different locations of the solar cell, the arrangement of the contact portions of the first current collector electrode and the second current collector electrode can be specially designed in specific areas of the solar cell.

[0099] Figure 10 This is a top view schematic diagram of a solar cell provided according to another embodiment of the present invention. Specifically, taking at least one first current collector electrode 41 as an example, refer to... Figure 10 As shown, the first transmission section 412 has disconnected portions spaced apart along a first direction at its middle position. The disconnected portions and / or ends of the first transmission section 412 have third contact portions 413, the length R3 of which is different from the length R2 of the first contact portion. Similarly, the second current collector 42 can be configured in the same way as the first current collector 41, and will not be described again. Furthermore, the specific applicability of the third contact portion configuration at the disconnected portions and / or ends of the first transmission section 412 in different solar cells is explained below.

[0100] like Figure 4 and Figure 8As shown, taking a back-contact battery as an example, the solar cell may also include a plurality of second busbars 44, with a passivation layer 30 disposed on the side away from the semiconductor substrate 10. The plurality of second busbars 44 are arranged at intervals along the first direction X and each extends along the second direction Y. The second busbars 44 are electrically connected to the second current collector 42.

[0101] Similar to the first busbar 43, in a back-contact solar cell without a main grid structure, such as Figure 8 As shown, the second bus 44 may include a second solder point 442. Further, at least a portion of the second bus 44 may include two opposing second terminal lines (only one second terminal line is shown in the figure), with the second solder point 442 electrically connected to the second terminal line.

[0102] At this time, in at least one first collector electrode, the first transmission section 412 is disconnected at the intersection with the second terminal line or the second solder point 442, forming a disconnection section A, thereby electrically isolating it from the second bus 44. At this time, the disconnection section A of the first collector electrode 41 has a third contact portion that contacts through the passivation layer 30 and the first doped conductive layer 21. By setting the length of the third contact portion at the disconnection section A to be different from the length of the first contact portion, space can be provided for the arrangement of the second bus, thereby better avoiding the risk of short circuits at the intersection with the second bus 44.

[0103] Of course, this is not the only possibility. In back-contact solar cells with a main grid structure, at least part of the busbar may include a second busbar electrode that extends continuously in the second direction, and a second solder joint that is electrically connected to the second busbar electrode. In this case, the first collector electrode 41 is disconnected at the intersection with the second busbar electrode or the second solder joint, forming a disconnection portion A. Similarly, by setting the length of the third contact portion at the disconnection portion A to be different from the length of the first contact portion, the risk of short circuit at the intersection with the second busbar 44 can be better avoided.

[0104] In some embodiments, such as Figure 7 As shown, taking a bifacial contact cell as an example, in the first current collector electrode located at the edge of the cell, the first current collector electrode 41 is disconnected at the connection point with the first end line, forming a disconnection portion A. This reduces the mechanical stress at the edge of the solar cell, thereby lowering the risk of cracking. At this time, the first current collector electrode 41 has a third contact portion near its disconnection portion A along the first direction X, which contacts the passivation layer 30 and the first doped conductive layer 21. By setting the length of the third contact portion at the disconnection portion A to be different from the length of the first contact portion, both the mechanical stress at the edge of the solar cell and the carrier collection effect can be considered.

[0105] In some embodiments, in a bifacial contact cell, a third contact portion is provided at the end B of the first current collector 41 near the cell edge, and the third contact portion contacts the passivation layer 30 and the first doped conductive layer 21. For a back-contact cell, the same arrangement is made at the end B of the first current collector 41 near the cell edge, and will not be described further. By setting the length of the third contact portion at end B to be different from the length of the first contact portion, both the mechanical stress at the edge of the solar cell and the carrier collection effect can be considered.

[0106] Figure 11 This is a top view schematic diagram of the first collector electrode provided in an embodiment of the present invention.

[0107] In an embodiment of the present invention, reference is made to... Figure 11 As shown, along the second direction Y, the width D1 of the first contact portion 411 along the second direction Y is smaller than the width D2 of the first transmission portion 412 along the second direction Y.

[0108] In some embodiments, the ratio of the width D2 of the first transmission portion 412 along the second direction Y to the width D1 of the first contact portion 411 along the second direction Y is 0.8 to 2.5; for example, it can be 0.8, 1.0, 1.5, 2, 2.5, but is not limited to the values ​​mentioned.

[0109] In some embodiments, the width D1 of the first contact portion 411 along the second direction Y is 10~50μm, and the width D2 of the first transmission portion 412 along the second direction Y is 30~100μm.

[0110] In an embodiment of the present invention, the width of the first contact portion along the second direction is smaller than the width of the first transmission portion along the second direction, which is beneficial to increase the contact area between the first contact portion and the first transmission portion, thereby reducing the transmission resistance of the first collector electrode.

[0111] Figure 12 A top view schematic diagram of the first collector electrode provided in another embodiment of the present invention.

[0112] In an embodiment of the present invention, reference is made to... Figure 12 As shown, in at least one first transmission section 412, a plurality of first contact sections 411 electrically connected to the first transmission section 412 are distributed in at least two rows along the second direction Y.

[0113] Each row includes a plurality of first contact portions 411 arranged along the first direction X, and the first contact portions 411 of adjacent rows are staggered along the second direction.

[0114] In some embodiments, each row includes a plurality of first contact portions 411 arranged along a first direction X, and the first contact portions 411 of adjacent rows are end-aligned along a second direction.

[0115] In some embodiments, in at least one first transmission section 412, a plurality of first contact sections 411 electrically connected to the first transmission section 412 are distributed in multiple rows along the second direction Y, for example, in 3, 4, 5, 6, or 7 rows, but not limited to the values ​​mentioned above.

[0116] In an embodiment of the present invention, the first contact portions 411 of two adjacent rows in the same first collector electrode are staggered along the second direction Y, which is more conducive to collecting charge carriers and improves the uniformity and effectiveness of charge carrier collection.

[0117] In an embodiment of the present invention, the first contact portions 411 of two adjacent rows are aligned at their ends along the second direction Y, which helps to simplify the fabrication process of the first collector electrode.

[0118] In embodiments of the present invention, in at least one pair of adjacent first collector electrodes 41, the first contact portions 411 are staggered along the second direction Y. In some embodiments, in at least one pair of adjacent first collector electrodes 41, the first contact portions 411 may also be aligned along the second direction Y.

[0119] According to an embodiment of the present invention, in a pair of adjacent first collector electrodes 41, the first contact portions 411 are staggered along the second direction Y, which can be more conducive to collecting charge carriers and improve the uniformity and effectiveness of charge carrier collection.

[0120] In an embodiment of the present invention, in a pair of adjacent first collector electrodes 41, the first contact portion 411 is end-aligned along the second direction Y. This arrangement is beneficial to simplifying the fabrication process of the first collector electrode.

[0121] To facilitate understanding of the specific application of the first and second current collector electrodes provided by this invention in solar cells, a TBC cell will be used as an example for detailed explanation below. The solar cell of this invention may include a semiconductor substrate 10, a first doped conductive layer 21, a second doped conductive layer 22, a passivation layer 30, a plurality of first current collector electrodes 41, and a plurality of second current collector electrodes 42.

[0122] refer to Figure 4As shown, the solar cell is a TBC cell, wherein the first doped conductive layer 21 can be a P-type doped polycrystalline silicon layer, and the second doped conductive layer 22 can be an N-type doped polycrystalline silicon layer, which are alternately disposed on the first surface of the semiconductor substrate 10. The solar cell may further include a first tunneling layer 51 and a second tunneling layer 52. The first tunneling layer 51 is located between the semiconductor substrate 10 and the first doped conductive layer 21, forming a TOPCon structure with the first doped conductive layer 21. The second tunneling layer 52 is located between the semiconductor substrate 10 and the second doped conductive layer 22, forming a TOPCon structure with the second doped conductive layer 22. The solar cell may further include another antireflection layer 60, located on the second surface of the semiconductor substrate 10 opposite to the first surface.

[0123] The first collector electrode 41 includes a plurality of first contact portions 411 and a first transmission portion 412. The plurality of first contact portions 411 pass through the passivation layer 30 and are electrically connected to the first doped conductive layer 21. The plurality of first contact portions 411 are spaced apart along the first direction S1. The first transmission portion 412 is disposed on the side of the first contact portion 411 away from the semiconductor substrate 10 and is in contact with the plurality of first contact portions 411. The first transmission portion 412 extends along the first direction S1.

[0124] The second collector electrode 42 includes a plurality of second contact portions 421 and a second transmission portion 422. The plurality of second contact portions 421 pass through the passivation layer 30 and are electrically connected to the second doped conductive layer 22. The plurality of second contact portions 421 are spaced apart along the first direction S1. The second transmission portion 422 is disposed on the side of the second contact portions 421 away from the semiconductor substrate 10 and is in contact with the plurality of second contact portions 421. The second transmission portion 422 extends along the first direction S1. The specific arrangement of the first collector electrode 41 and the second collector electrode 42 is the same as described above, so it will not be repeated. Of course, in some other examples, the second collector electrode 42 can also adopt a conventional electrode structure, that is, the second collector electrode 42 is an integral structure that directly passes through the passivation layer 30 and is electrically connected to the second doped conductive layer 22.

[0125] According to another embodiment of the present invention, a method for fabricating a solar cell is also provided. This method can be used to fabricate the solar cells provided in any of the above embodiments. (Refer to...) Figure 3 As shown, the method for fabricating a solar cell according to an embodiment of the present invention includes operations S101 to S104. It should be noted that the sequence numbers of S101 to S104 do not indicate that these operations must be performed in sequence; the order of these operations can be adjusted as needed.

[0126] In operation S101, a first doped conductive layer 21 and a second doped conductive layer 22 are fabricated on the semiconductor substrate 10.

[0127] In operation S102, a passivation layer 30 is formed on the first doped conductive layer 21 and the second doped conductive layer 22.

[0128] In operation S103, a plurality of first contact portions 411 are formed on the side of the passivation layer 30 away from the first doped conductive layer 21, and a plurality of second contact portions 421 are formed on the side of the passivation layer 30 away from the second doped conductive layer 22. The plurality of first contact portions 411 pass through the passivation layer 30 to contact the first doped conductive layer 21, and the plurality of second contact portions 421 pass through the passivation layer 30 to contact the second doped conductive layer 22.

[0129] In operation S104, a plurality of first transmission portions 412 extending in a first direction and spaced apart in a second direction are formed on a plurality of first contact portions 411. Each first transmission portion 412 is electrically connected to the plurality of first contact portions 411 spaced apart in the first direction and forms a first collector electrode 41. A plurality of second transmission portions 422 extending in the first direction and spaced apart in the second direction are formed on a plurality of second contact portions 421. Each second transmission portion 422 is electrically connected to the plurality of second contact portions 421 spaced apart in the first direction and forms a second collector electrode 42.

[0130] According to embodiments of the present invention, based on the original preparation process of the first doped conductive layer, the second doped conductive layer, and the passivation layer, the present invention improves the preparation method of the first current collector electrode and the second current collector electrode by using high-temperature slurry to prepare multiple intermittently distributed contact portions. This reduces the amount of high-temperature slurry used and lowers the process cost while ensuring contact performance. At the same time, by differentiating the dimensions of the first contact portion and the second contact portion, the balance of carrier collection of the first doped conductive layer and the second doped conductive layer can be taken into account, thereby improving the battery efficiency.

[0131] According to embodiments of the present invention, prior to operation S101, a surface treatment operation on the semiconductor substrate 10 may be included, such as texturing and / or polishing. Exemplarily, a silicon substrate is texturized to form a textured structure including multiple pyramids.

[0132] According to embodiments of the present invention, a first doped conductive layer 21 and a second doped conductive layer 22 can be fabricated on the surface of a semiconductor substrate by combining techniques such as diffusion, laser drilling, ion implantation and annealing, masking, and etching. Since existing fabrication processes in the art can be used and are not key points of the present invention, they will not be described in detail.

[0133] According to an embodiment of the present invention, in operation S102, the passivation layer of the present invention can be a single layer or multiple layers. The specific material selection is the same as described above and will not be repeated here. As for the preparation method of the passivation layer, it can be specifically selected according to its material and structure. It can be ALD, various CVD (e.g., PECVD, APCVD, LPCVD, MOCVD, etc.), various PVD (evaporation, sputtering, etc.).

[0134] For example, an alumina passivation layer is first prepared using ALD (atomic layer deposition), and then one or more silicon nitride layers are formed on top of it using PECVD. Of course, it is not limited to ALD and PECVD methods; it can also be prepared using APCVD, LPCVD, MOCVD, PVD (such as evaporation and sputtering), etc.

[0135] According to some embodiments of the present invention, the solar cell can be a double-sided contact cell, with the first doped conductive layer 21 and the second doped conductive layer 22 respectively located on the opposite first and second surfaces of the semiconductor substrate 10, and the passivation layer 30 can be formed on the first doped conductive layer 21 and the second doped conductive layer 22 respectively; or, the solar cell can be a back contact cell, with the first doped conductive layer 21 and the second doped conductive layer 22 alternately disposed on the first surface, and the passivation layer 30 can be formed on the first doped conductive layer 21 and the second doped conductive layer 22 simultaneously.

[0136] According to an embodiment of the present invention, in operation S103, a first contact portion 411 and a second contact portion 421 can be prepared on the passivation layer using a screen printing method, and then sintered, so that the electrode paste passes through the passivation layer 30 and contacts the first doped conductive layer 21 and the second doped conductive layer 22 respectively. The first contact portion 411 and the second contact portion 421 can be prepared simultaneously or separately. Further optionally, the electrode paste can include metal particles such as silver, nickel, copper, and / or zinc.

[0137] According to an embodiment of the present invention, in operation S104, electrode paste, which may be the same as or different from the first contact portion or the second contact portion, can be printed on the first contact portion 411 and the second contact portion 421 to form the first transport portion 412 and the second transport portion 422. The first transport portion 412 and the second transport portion 422 can be fabricated simultaneously or separately. Further optionally, the electrode paste may include base metal particles, such as low-temperature silver-coated copper paste, low-temperature copper paste, low-temperature nickel paste, etc. Here, "low-temperature" can mean that the sintering temperature of the paste is below 300°C, especially below 250°C.

[0138] The above describes the fabrication of the first and second current collector electrodes using printing and sintering methods. However, this method is not limited to these techniques. For example, the first and second contact portions can be fabricated by laser grooving the passivation layer followed by electroplating, and then the first and second transmission portions can be printed. In this case, using electroplating to prepare the seed layer helps reduce metal recombination and minimize battery efficiency loss.

[0139] According to an exemplary embodiment of the present invention, the present invention provides a photovoltaic module, including a plurality of the above-described solar cells connected to form a solar cell string; and an encapsulation layer covering the surface of the plurality of solar cells.

[0140] According to embodiments of the present invention, the number of solar cells connected in series can be 4 to 80 or even more. Multiple solar cells can form several battery strings, each battery string containing the same number of solar cells. The cells within a battery string are connected in series, and the battery strings can be connected in series or in parallel.

[0141] According to embodiments of the present invention, the encapsulation layer may include a backsheet, an encapsulating film, a glass panel, etc., to improve the stability of the solar cell string. The glass panel is located on the front of the solar cell string, and the backsheet is located on the back of the solar cell string, both serving a protective function. The adhesive film is an adhesive film between the solar cell string and the glass panel and backsheet, serving a bonding and fixing function, and must be made of a transparent material.

[0142] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A solar cell, characterized by, Comprising: a semiconductor substrate comprising a first surface and a second surface; a first doped conductive layer disposed on the first surface of the semiconductor substrate, the first doped conductive layer having the same conductivity type as the semiconductor substrate; a first tunneling layer disposed between the first doped conductive layer and the semiconductor substrate, the first tunneling layer and the first doped conductive layer forming a tunneling passivation contact structure; a second doped conductive layer disposed on the second surface of the semiconductor substrate, the second doped conductive layer being disposed opposite to the first doped conductive layer, or the second doped conductive layer and the first doped conductive layer being alternately disposed on the first surface; the second doped conductive layer having a different conductivity type from the semiconductor substrate; a plurality of first current collecting electrodes disposed on the first surface of the semiconductor substrate, the plurality of first current collecting electrodes extending along a first direction and being spaced apart along a second direction; the first current collecting electrode comprising a plurality of first contact portions and a first transmission portion, the plurality of first contact portions being spaced apart along the first direction, the plurality of first contact portions being electrically connected to the first doped conductive layer; the first transmission portion being disposed on a side of the first contact portion away from the semiconductor substrate and being in contact with the plurality of first contact portions, the first transmission portion extending along the first direction; a plurality of second current collecting electrodes disposed on the first surface and being alternately spaced apart from the plurality of first current collecting electrodes, or disposed on the second surface, the plurality of second current collecting electrodes extending along a first direction and being spaced apart along a second direction; the second current collecting electrode comprising a plurality of second contact portions and a second transmission portion, the plurality of second contact portions being spaced apart along the first direction, the plurality of second contact portions being electrically connected to the second doped conductive layer; the second transmission portion being disposed on a side of the second contact portion away from the semiconductor substrate and being in contact with the plurality of second contact portions, the second transmission portion extending along the first direction; wherein, in at least one pair of adjacent first current collecting electrodes, a spacing between at least one pair of adjacent first contact portions in the first direction is less than or equal to a spacing between the pair of adjacent first current collecting electrodes in the second direction; in at least one first current collecting electrode, a ratio of a length of at least one first contact portion along the first direction to a spacing between the first contact portion and another first contact portion adjacent to the first contact portion is less than a ratio of a length of at least one second contact portion along the first direction to a spacing between the second contact portion and another second contact portion adjacent to the second contact portion in at least one second current collecting electrode; in at least one first current collecting electrode, a spacing between at least one pair of adjacent first contact portions is greater than a spacing between at least one pair of adjacent second contact portions in at least one second current collecting electrode.

2. The solar cell according to claim 1, characterized in that, Further comprising: a passivation layer disposed on a side of the first doped conductive layer away from the semiconductor substrate; The first contact portions are arranged on the first surface of the first doped conductive layer, and the first contact portions are electrically connected to the first doped conductive layer.

3. The solar cell of claim 1, wherein In at least one of the first collecting electrodes, a spacing between at least one pair of adjacent first contact portions in the first direction is less than or equal to 1.5 mm. In at least one of the first collecting electrodes, a spacing between at least one pair of adjacent first contact portions in the first direction is less than or equal to 1.5 mm.

4. The solar cell according to claim 1 or 2, characterized in that, In at least one of the first collecting electrodes, a spacing between at least one pair of adjacent first contact portions in the first direction is less than or equal to 1.5 mm.

5. The solar cell of claim 1, wherein In at least one of the first collecting electrodes, a spacing between at least one pair of adjacent first contact portions in the first direction is less than or equal to 1.5 mm. In at least one of the first collecting electrodes, a spacing between at least one pair of adjacent first contact portions in the first direction is less than or equal to 1.5 mm.

6. The solar cell of claim 1, wherein In at least one of the first collecting electrodes, a spacing between at least one pair of adjacent first contact portions in the first direction is less than or equal to 1.5 mm.

7. The solar cell of claim 1, wherein In at least one of the first collecting electrodes, a spacing between at least one pair of adjacent first contact portions in the first direction is less than or equal to 1.5 mm.

8. The solar cell of claim 1, wherein, In at least one of the first collecting electrodes, a spacing between at least one pair of adjacent first contact portions in the first direction is less than or equal to 1.5 mm. The first contact portions comprise at least one of silver, nickel, titanium, and a transparent conductive oxide.

9. The solar cell of claim 1, wherein, The first transmission portion comprises at least one of copper, aluminum, silver-coated copper, and silver-copper alloy.

10. The solar cell of claim 1, wherein, The solar cell further comprises at least one first soldering point arranged on the first surface and connected to at least one first collecting electrode, and a length of the first soldering point in the first direction is greater than a spacing between adjacent first contact portions.

11. The solar cell of claim 1, wherein, In at least one of the first collecting electrodes, a middle position of the first transmission portion has a plurality of broken portions arranged at intervals in the first direction, and the first transmission portion has a third contact portion at a broken portion and / or an end portion, and a length of the third contact portion is different from a length of the first contact portion. In the second direction, a width of the first contact portion in the second direction is less than a width of the first transmission portion in the second direction. In the second direction, a width of the first contact portion in the second direction is less than a width of the first transmission portion in the second direction.

12. The solar cell of claim 1, wherein, In the second direction, a width of the first contact portion in the second direction is less than a width of the first transmission portion in the second direction. In at least one of the first transmission portions, a plurality of first contact portions electrically connected to the first transmission portion are distributed in at least two rows in the second direction. Each row comprises a plurality of first contact portions arranged in the first direction, and adjacent rows of first contact portions are arranged in a staggered manner in the second direction.

13. The solar cell of claim 1, wherein, In at least one pair of adjacent first current collecting electrodes, the first contact portions are staggered in a second direction.

14. A photovoltaic module, characterized by, Comprising: a plurality of solar cells as claimed in any one of claims 1 to 13 connected into a solar cell string; and a packaging layer covering the surface of the plurality of solar cells.

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