Screen structure, solar cell, photovoltaic module, and method for printing solar cell

Abstract

The present application discloses a screen structure, a solar cell, a photovoltaic module, and a method for printing the solar cell. The screen structure comprises a first screen and a second screen. The first screen comprises a substrate. The substrate is provided with a plurality of finger printing areas. The plurality of finger printing areas are arranged at intervals in a first direction. Each finger printing area comprises a plurality of finger printing holes. The plurality of finger printing holes are arranged at intervals in a second direction. The plurality of finger printing holes in each finger printing area are configured such that fingers provided with gaps are formed on a semi-finished solar cell. The second screen is provided with connection printing areas. The connection printing areas are configured to form on the semi-finished solar cell connection structures located at the gaps. Each connection structure is configured to be connected between the fingers located at two sides of the corresponding gap in the second direction. The screen structure, the solar cell, the photovoltaic module, and the method for printing the solar cell of the present application can reduce the occurrence of defects of the fingers such as finger break and weak printing while narrowing the linewidth of the fingers and reducing the cost of a paste.

Description

Methods for screen printing structure, solar cells, photovoltaic modules, and printed solar cells Technical Field

[0001] This application relates to the field of solar cell technology, and more particularly to a screen printing structure, a solar cell, a photovoltaic module, and a method for printing solar cells. Background Technology

[0002] Currently, the electrode structure of solar cells mainly adopts screen printing technology, which prints grid lines on the semi-finished solar cell by printing a preset pattern on the screen.

[0003] In related technologies, in order to reduce paste loss and lower the manufacturing cost of solar cells, the linewidth of the sub-grid is usually narrowed. However, narrowing the linewidth of the sub-grid can lead to printing defects such as broken grids and incomplete printing. Summary of the Invention

[0004] This application discloses a screen printing structure, a solar cell, a photovoltaic module, and a method for printing solar cells. While narrowing the sub-grid linewidth and reducing paste costs, it can also reduce printing defects such as broken grids and incomplete printing of sub-grids.

[0005] To achieve the above objectives, in a first aspect, embodiments of this application disclose a screen printing structure applied to a solar cell, the solar cell including a solar cell semi-finished product, and the screen printing structure including:

[0006] The first screen printing plate includes a substrate. The substrate has multiple sub-gate printing areas. The multiple sub-gate printing areas are spaced apart along a first direction. Each sub-gate printing area includes multiple sub-gate printing holes. The multiple sub-gate printing holes are spaced apart in a second direction. The multiple sub-gate printing holes in each sub-gate printing area are configured to form a sub-gate with a break on the solar cell semi-finished product.

[0007] The second screen has a connecting printing area, which is configured to form a connecting structure on the solar cell semi-finished product located at the break, and the connecting structure is configured to connect between the sub-grids located on both sides of the break in the second direction.

[0008] The first direction and the second direction intersect.

[0009] As an optional implementation, in the embodiment of the first aspect of this application, the width D1 of the sub-gate printed hole in the first direction is 2μm to 30μm.

[0010] As an optional implementation, in the embodiment of the first aspect of this application, in the second direction, a gap region is formed between two adjacent sub-gate printing holes, the length of the sub-gate printing holes in the second direction is D2, the width of the gap region in the second direction is D3, and D2 / D3 is 35 to 240.

[0011] As an optional implementation, in the embodiment of the first aspect of this application, the length D2 of the sub-gate printing hole in the second direction is 5mm to 30mm, and the width D3 of the spacing region in the second direction is 0.05mm to 1.5mm.

[0012] As an optional implementation, in an embodiment of the first aspect of this application, the connection printing area includes a first connection printing hole, a second connection printing hole, and an intermediate connection printing hole. The intermediate connection printing hole communicates between the first connection printing hole and the second connection printing hole. The first connection printing hole is configured to form a first connection line on the solar cell semi-finished product, and the first connection line is connected to a sub-gate located on one side of the break in a second direction. The second connection printing hole is configured to form a second connection line on the solar cell semi-finished product, and the second connection line is connected to a sub-gate located on the other side of the break in a second direction. The intermediate connection printing hole is configured to form an intermediate connection line on the solar cell semi-finished product, and the intermediate connection line is connected between the first connection line and the second connection line.

[0013] As an optional implementation, in the embodiment of the first aspect of this application, the width of the sub-gate printing hole in the first direction is D1, and the shortest length of the first connecting printing hole and the second connecting printing hole in the first direction is D4, where D4≥D1.

[0014] As an alternative implementation, in the embodiment of the first aspect of this application, the length D5 of the connecting printing area in the second direction is 0.05mm to 1.5mm.

[0015] As an optional implementation, in the embodiment of the first aspect of this application, the shortest length D4 of the first connecting printed hole and the second connecting printed hole in the first direction is 20μm to 200μm, and / or, the width D6 of the first connecting printed hole and the second connecting printed hole in the second direction is 10μm to 200μm, and / or, the width D7 of the intermediate connecting printed hole in the first direction is 10μm to 200μm.

[0016] As an alternative implementation, in the embodiments of the first aspect of this application, the shape of the connecting printing area includes at least one of H-shape, N-shape or inverted figure-eight shape.

[0017] As an optional implementation, in the embodiment of the first aspect of this application, the second screen does not have a main grid printing area. In the second direction, an interval area is formed between two adjacent sub-grid printing holes. The length of the sub-grid printing hole in the second direction is D2, the width of the interval area in the second direction is D3, the number of interval areas is M, and the aperture ratio of the first screen is F, F = D2(M+1) / [D2(M+1)+D3*M], 90% ≤ F < 100%.

[0018] As an alternative implementation, in an embodiment of the first aspect of this application, the second screen printing plate is further provided with a main grid printing area, which is configured to form a main grid on the solar cell semi-finished product;

[0019] The main grid printing area is spaced apart from the connecting printing area in the second direction, and / or the connecting printing area is at least partially connected to the main grid printing area.

[0020] As an optional implementation, in the embodiment of the first aspect of this application, the number of main grid printing areas is N, and in the second direction, a gap area is formed between two adjacent sub-grid printing holes. The number M of the gap area of ​​each sub-grid printing area is: 1 / 10N≤M≤20N; where N is an integer and N≥1, and M is an integer.

[0021] As an optional implementation, in the embodiment of the first aspect of this application, the main grid printing area includes multiple main grid printing areas, which are spaced apart along the second direction. When the main grid printing areas are spaced apart from the connecting printing areas in the second direction, the connecting printing areas are located between two adjacent main grid printing areas.

[0022] As an optional implementation, in an embodiment of the first aspect of this application, when the main grid printing area is spaced apart from the connecting printing area in the second direction, the second screen is further provided with a main grid overlapping printing area. The main grid overlapping printing area is at least partially located on the main grid printing area and communicates with the main grid printing area. The main grid overlapping printing area is configured to form a main grid overlapping structure located at the intersection of the main grid and the sub-grid on the solar cell semi-finished product.

[0023] As an optional implementation, in an embodiment of the first aspect of this application, the substrate further includes a sub-gate overlap printing area, which is at least partially located on the sub-gate printing area and communicates with the sub-gate printing hole. The sub-gate overlap printing area is configured to form a sub-gate overlap structure on the solar cell semi-finished product, and the sub-gate overlap structure is at least partially overlapped with the main gate overlap structure.

[0024] As an optional implementation, in the embodiment of the first aspect of this application, the main gate overlap structure covers the secondary gate overlap structure; or,

[0025] The sub-gate overlap structure covers the main gate overlap structure.

[0026] As an optional implementation, in the embodiment of the first aspect of this application, when the main gate overlap structure covers the sub-gate overlap structure, the maximum width T1 of the main gate overlap printing area in the first direction is 30μm to 80μm, the minimum width T2 of the main gate overlap printing area in the first direction is 13μm to 80μm, the length T3 of the main gate overlap printing area in the second direction is 0.6mm to 1.6mm, the maximum width T4 of the sub-gate overlap printing area in the first direction is 15μm to 70μm, the minimum width T5 of the sub-gate overlap printing area in the first direction is 10μm to 70μm, and the length T6 of the sub-gate overlap printing area in the second direction is 0.5mm to 1.5mm; or,

[0027] When the sub-grid overlap structure covers the main grid overlap structure, the maximum width T1 of the main grid overlap printed area in the first direction is 15μm to 70μm, the minimum width T2 of the main grid overlap printed area in the first direction is 10μm to 70μm, the length T3 of the main grid overlap printed area in the second direction is 0.5mm to 1.5mm, the maximum width T4 of the sub-grid overlap printed area in the first direction is 30μm to 80μm, the minimum width T5 of the sub-grid overlap printed area in the first direction is 13μm to 80μm, and the length T6 of the sub-grid overlap printed area in the second direction is 0.6mm to 1.6mm. In a second aspect, this application also discloses a solar cell, comprising:

[0028] Semi-finished solar cells;

[0029] The electrode structure includes multiple sub-gates and a connecting structure. The multiple sub-gates are spaced apart along a first direction. Each sub-gate includes multiple sub-sub-gates. The multiple sub-sub-gates are spaced apart in a second direction to form a break between two adjacent sub-sub-gates. The connecting structure is located at the break and is connected between two adjacent sub-sub-gates in the second direction.

[0030] The first direction and the second direction intersect.

[0031] As an optional implementation, in an embodiment of the second aspect of this application, the width W1 of the sub-gate in the first direction is 4μm to 30μm.

[0032] As an optional implementation, in an embodiment of the second aspect of this application, the height H of the cross-section of the sub-gate is 1 μm to 10 μm, and / or the smoothing factor of the sub-gate in the height direction is less than or equal to 1.

[0033] As an optional implementation, in an embodiment of the second aspect of this application, the connection structure includes a first connecting line, a second connecting line, and an intermediate connecting line. The first connecting line is connected to one of the sub-gates located on one side of the break in the second direction, the second connecting line is connected to another sub-gate located on the other side of the break in the second direction, and the intermediate connecting line is connected between the first connecting line and the second connecting line.

[0034] As an optional implementation, in an embodiment of the second aspect of this application, the width of the sub-gate in the first direction is W1, and the shortest length of the first connecting line and the second connecting line in the first direction is W2, where W2 ≥ W1.

[0035] As an alternative implementation, in an embodiment of the second aspect of this application, the length W3 of the connecting structure in the second direction is 0.05 mm to 1.6 mm.

[0036] As an optional implementation, in an embodiment of the second aspect of this application, the shortest length W2 of the first connecting line and the second connecting line in the first direction is 40μm to 120μm, and / or the width W4 of the first connecting line and the second connecting line in the second direction is 2μm to 60μm, and / or the width W5 of the intermediate connecting line in the first direction is 2μm to 60μm.

[0037] As an alternative implementation, in an embodiment of the second aspect of this application, the shape of the connection structure includes at least one of H-shape, N-shape, or inverted figure-eight shape.

[0038] As an alternative implementation, in an embodiment of the second aspect of this application, the electrode structure further includes a main grid, which is spaced apart from the break in a second direction, and / or the break is located on the main grid.

[0039] As an optional implementation, in an embodiment of the second aspect of this application, the main grid includes multiple main grids, which are spaced apart along a second direction. When the main grids are spaced apart from the break in the second direction, the break is located between two adjacent main grids.

[0040] As an optional implementation, in an embodiment of the second aspect of this application, when the main grid is spaced apart from the break in the second direction, the electrode structure further includes a main grid overlap structure, which is connected to the main grid and located at the intersection of the main grid and the sub-grid.

[0041] As an optional implementation, in an embodiment of the second aspect of this application, the electrode structure further includes a sub-gate overlap structure, which is connected to the sub-sub-gate, and the sub-gate overlap structure and the main gate overlap structure are at least partially overlapped.

[0042] As an optional implementation, in an embodiment of the second aspect of this application, the main gate overlap structure covers the secondary gate overlap structure; or,

[0043] The sub-gate overlap structure covers the main gate overlap structure.

[0044] As an optional implementation, in the embodiment of the second aspect of this application, when the main gate overlap structure covers the sub-gate overlap structure, the maximum width L1 of the main gate overlap structure in the first direction is 35μm to 90μm, the minimum width L2 of the main gate overlap structure in the first direction is 20μm to 90μm, the length L3 of the main gate overlap structure in the second direction is 0.65mm to 1.7mm, the maximum width L4 of the sub-gate overlap structure in the first direction is 20μm to 75μm, the minimum width L5 of the sub-gate overlap structure in the first direction is 15μm to 75μm, and the length L6 of the sub-gate overlap structure in the second direction is 0.55mm to 1.6mm; or,

[0045] When the sub-gate overlap structure covers the main gate overlap structure, the maximum width L1 of the main gate overlap structure in the first direction is 20μm to 75μm, the minimum width L2 of the main gate overlap structure in the first direction is 15μm to 75μm, the length L3 of the main gate overlap structure in the second direction is 0.55mm to 1.6mm, the maximum width L4 of the sub-gate overlap structure in the first direction is 35μm to 90μm, the minimum width L5 of the sub-gate overlap structure in the first direction is 20μm to 90μm, and the length L6 of the sub-gate overlap structure in the second direction is 0.65mm to 1.7mm.

[0046] As an optional implementation, in the embodiment of the second aspect of this application, the electrode structure further includes pads and a fork. The pads include first pads and second pads. First pads are provided at both ends of the main gate, and the second pads are provided on the main gate and located between the two first pads. The fork is located at both ends of the main gate and connected to the first pads.

[0047] The area of ​​the first pad is larger than the area of ​​the second pad.

[0048] Thirdly, this application also discloses a photovoltaic module, including a solar cell as described in the second aspect above.

[0049] Fourthly, this application also discloses a method for printing solar cells using the screen printing structure as described in the first aspect above, the method comprising:

[0050] Using the first screen printing plate, a sub-grid with a break is printed on the semi-finished solar cell;

[0051] Multiple connection structures are printed on the semi-finished solar cell using a second screen printing plate, so that the connection structures connect between the sub-grids located on both sides of the break.

[0052] This application discloses a screen printing structure comprising a first screen and a second screen. By directly setting a sub-grid printing area on the substrate of the first screen, the ink can directly penetrate the sub-grid printing area during printing, resulting in a smoother and more uniform ink penetration process. This prevents printing defects such as broken sub-grids and incomplete printing. Furthermore, by directly opening holes in the steel plate, the width of the sub-grid printing area can be made smaller as needed, thereby enabling the printing of sub-grids with narrower linewidths and reducing wet weight.

[0053] Based on this, the sub-grid printing area is divided into spaced sub-grid printing holes. When there are a large number of sub-grid printing areas, the structural strength of the first screen is increased, the mechanical structural stability of the first screen is improved, thereby reducing the risk of the first screen bursting during printing and thus extending the service life of the first screen.

[0054] Meanwhile, by setting a connecting printing area on the second screen, the paste forms a connecting structure on the substrate through the connecting printing area, connecting the sub-grids located on both sides of the fracture, so that the sub-grids with fractures form complete grid lines. This setting allows current to be collected through the sub-grids, and during laser-induced sintering and IV / EL testing, the entire solar cell can be powered on and tested without modifying the equipment, which is beneficial to improving the versatility of the measurement equipment. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 is a schematic diagram of the structure of the first web version disclosed in the first aspect of this application.

[0057] Figure 2 is a schematic diagram of the structure of the second web version disclosed in the first aspect of this application.

[0058] Figure 3 is an enlarged schematic diagram of point A in Figure 1.

[0059] Figure 4 is a schematic diagram of the structure of the connecting printing area disclosed in the first aspect of this application.

[0060] Figure 5a is a schematic diagram of a modified structure of the connecting printing area disclosed in the first aspect of this application.

[0061] Figure 5b is a schematic diagram of another modified structure of the connecting printing area disclosed in the first aspect of this application.

[0062] Figure 5c is a schematic diagram of another modified structure of the connecting printing area disclosed in the first aspect of this application.

[0063] Figure 6 is an enlarged view of point B in Figure 2.

[0064] Figure 7 is a schematic diagram of the structure of the main grid overlap printing area disclosed in the first aspect of this application.

[0065] Figure 8 is a schematic diagram of the structure of the sub-gate overlap printing area disclosed in the first aspect of this application.

[0066] Figure 9 is a partial structural diagram of the first web version disclosed in the second aspect of this application.

[0067] Figure 10 is a partial structural diagram of the second web version disclosed in the second aspect of this application.

[0068] Figure 11 is a schematic diagram of the connection between the main gate and the sub-gate disclosed in the second aspect of this application.

[0069] Figure 12 is a schematic diagram of the electrode structure disclosed in the third aspect of this application.

[0070] Figure 13 is an enlarged schematic diagram of point C in Figure 12.

[0071] Figure 14 shows a schematic cross-sectional view of the sub-gate disclosed in the third aspect of this application.

[0072] Figure 15 shows a schematic diagram of the connection structure disclosed in the third aspect of this application.

[0073] Figure 16 is a schematic diagram of the structure disclosed in the third aspect of this application, in which the fracture is located on the main gate.

[0074] Figure 17 is a schematic diagram of the structure of the main grid overlap printing area covering the sub-grid overlap structure disclosed in the third aspect of this application.

[0075] Figure 18 is a schematic diagram of the structure of the sub-gate overlap printing area covering the main gate overlap structure disclosed in the third aspect of this application.

[0076] Figure 19 shows one of the topographic images of the sub-grid formed by wire mesh printing.

[0077] Figure 20 is the second morphological diagram of the sub-grid formed by wire mesh printing.

[0078] Figure 21 is one of the topographic images of the sub-grid formed by printing using the first screen printing method of this application.

[0079] Figure 22 is a second morphological diagram of the sub-grid formed by printing using the first screen printing method of this application.

[0080] Figure 23 is a cross-sectional profile of the sub-grid formed by wire mesh printing.

[0081] Figure 24 is a cross-sectional profile of the sub-grid formed by printing using the first screen printing method of this application.

[0082] Reference numerals: 10, Screen structure; 11, First screen; 110, Substrate; 111, Sub-gate printing area; 111a, Sub-gate printing hole; 111b, Spacing area; 112, Sub-gate overlapping printing area; 12, Second screen; 121, Connecting printing area; 1211, First connecting printing hole; 1212, Second connecting printing hole; 1213, Intermediate connecting printing hole; 122, Main gate printing area; 123, Main gate overlapping printing area; 20. Solar cell; 21. Solar cell semi-finished product; 22. Electrode structure; 221. Sub-grid; 221a. Break; 221b. Sub-grid; 222. Connection structure; 2221. First connecting line; 2222. Second connecting line; 2223. Intermediate connecting line; 223. Main grid; 224. Main grid overlap structure; 225. Sub-grid overlap structure; 226. Pad; 226a. First pad; 226b. Second pad; 227. Harpoon; X. First direction; Y. Second direction; D1. Width of sub-grid printed hole in the first direction; D2. Length of sub-grid printed hole in the second direction; D3. Width of spacing area in the second direction; D4. Shortest length of first and second connecting printed holes in the first direction; D5. Length of connecting printed area in the second direction; D6. Width of first and second connecting printed holes in the second direction; D7. Width of intermediate connecting printed hole in the first direction; T1, maximum width of the main grid overlap printing area in the first direction; T2, minimum width of the main grid overlap printing area in the first direction; T3, length of the main grid overlap printing area in the second direction; T4, maximum width of the secondary grid overlap printing area in the first direction; T5, minimum width of the secondary grid overlap printing area in the first direction; T6, length of the secondary grid overlap printing area in the second direction; W1, width of the secondary grid in the first direction; H, height of the secondary grid cross-section; W2, shortest length of the first connecting line and the second connecting line in the first direction; W3, length of the connecting structure in the second direction; W4, width of the first connecting line and the second connecting line in the second direction; W5, width of the intermediate connecting line in the first direction; L1, maximum width of the main grid overlap structure in the first direction; L2, minimum width of the main grid overlap structure in the first direction; L3, length of the main grid overlap structure in the second direction; L4, maximum width of the secondary grid overlap structure in the first direction; L5, minimum width of the secondary grid overlap structure in the first direction; L6, length of the secondary grid overlap structure in the second direction. Detailed Implementation

[0083] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0084] In this application, the terms "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0085] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0086] Furthermore, the terms "set up," "equipped with," and "connected" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0087] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0088] Solar cells, due to their cleanliness, safety, convenience, and high efficiency, have become a globally recognized and key industry for development. With continuous technological innovation, the conversion efficiency of solar cells is increasing dramatically, and high efficiency at low cost is gradually becoming the trend in solar cell technology development. For example, tunneling oxide passivated contact solar cells solve the problem of selective passivation contacts for charge carriers and improve the conversion efficiency of solar cells, achieving a conversion efficiency of up to 28.7%.

[0089] In related technologies, narrowing the grid linewidth is a common technique to obtain low-wet-weight solar cells while maintaining or reducing conductivity resistance. This reduces surface shading and conductive paste consumption, thereby lowering the cost of solar cells, which is significant for overall cost reduction and efficiency improvement in solar cell manufacturing. To narrow the grid linewidth, the main method is to optimize the screen printing process, shrinking the linewidth of the wire mesh for grid line printing. While this method effectively reduces the production cost of solar cells, the pressure to reduce costs and increase efficiency in the photovoltaic market limits the ability to simply optimize the screen to accommodate narrower linewidths. Specifically, currently used wire mesh printing processes experience significant printing defects after the linewidth is reduced to a certain level.

[0090] The inventors discovered that because the wire mesh is woven, the wires are interwoven and not on the same plane. This interweaving obstructs ink flow at the printing holes, hindering ink penetration and resulting in low transfer rates. Consequently, the printed image is uneven, with problems such as broken grids, incomplete printing, and poor flatness. Furthermore, the wire mesh's line width cannot be narrowed further beyond a certain limit, otherwise, severe printing defects will occur. This makes the wire mesh narrowing method a significant obstacle to reducing costs and improving efficiency in solar cells.

[0091] Based on this, the inventors attempted to introduce a new process screen, which includes a substrate with printing holes on the substrate. These holes are unobstructed, achieving a 100% opening rate. During printing, the ink can pass through the printing holes without obstruction, resulting in smoother and more uniform ink penetration, thus achieving ultra-fine line printing. This narrows the linewidth of the grid lines, resulting in low-wet-weight solar cells. It also reduces conductive ink loss and defects such as grid breakage, incomplete printing, and poor flatness. However, the inventors discovered that using screens with unobstructed printing holes leads to a short lifespan. Specifically, current screens are mainly used for printing sub-grids. When used for printing sub-grids, transverse openings are usually required on the screen surface to allow the ink to pass smoothly and unobstructed through the printing areas. To improve printing efficiency, multiple sub-grids are often formed during printing, resulting in 150 or more transverse openings on the screen surface. This significantly compromises the mechanical stability of the screen, making it prone to bursting during printing.

[0092] To address the aforementioned issue of low screen printing lifespan, the inventors modified the original long, straight sub-grid printing holes into segmented sub-grid printing holes, thereby enhancing the mechanical properties of the screen. Sub-grids typically use burn-through silver paste to etch a passivation layer in contact with the silicon substrate, collecting current and converging it at the main grid for conduction via solder ribbon or directly through the solder ribbon. However, segmented sub-grid printing holes on the screen create discontinuous sub-grids, which impair current transmission and prevent electro-injection onto the battery surface.

[0093] Based on this, this application provides a screen printing structure, which may include a first screen and a second screen. By directly setting sub-grid printing holes on the substrate of the first screen, the ink can directly seep into the sub-grid printing holes during printing. The ink seepage process is smoother and more uniform, thereby preventing printing defects such as broken sub-grids and incomplete printing. Moreover, the direct opening method allows for a smaller width of the sub-grid printing holes as needed, enabling the printing of sub-grids with narrower linewidths. Furthermore, dividing the sub-grid printing area into spaced sub-grid printing holes increases the structural strength of the first screen when there are a large number of sub-grid printing areas, improving the mechanical stability of the first screen and reducing the risk of screen bursting during printing, thus extending the service life of the first screen. Therefore, while achieving narrower linewidth sub-grids, reducing wet weight, and improving defects such as broken sub-grids and incomplete printing, the structural strength of the screen is increased, thereby reducing the risk of screen bursting during printing and extending the service life of the screen.

[0094] Building upon this, this application further incorporates a connecting printing area on the second screen, allowing the paste to form a connecting structure on the substrate, connecting the sub-grids located on both sides of the fracture, thereby enabling the sub-grids with fractures to form complete grid lines. This configuration allows current to be collected through the sub-grids, and during laser-induced sintering and IV (I-V curve testing, photoelectric performance testing) / EL (Electroluminescent testing) testing, the entire solar cell can be powered on and tested without equipment modification, thus improving the versatility of the measurement equipment.

[0095] The technical solution of this application will be further described below with reference to the embodiments and accompanying drawings.

[0096] In a first aspect, referring to Figures 1 and 12, this application provides a screen printing structure 10, which can be applied to a solar cell 20. The solar cell 20 includes a solar cell semi-finished product 21 and an electrode structure 22. Using the screen printing structure 10, paste can be printed onto the surface of the solar cell semi-finished product 21 according to a certain printing pattern through a printing process, and then sintered to form the electrode structure 22.

[0097] It should be noted that the solar cell semi-finished product 21 can refer to the semi-finished structure of the solar cell 20 before the electrode structure 22 is printed, or it can refer to the semi-finished structure of the solar cell 20 where the back electrode structure 22 has been printed, but the front electrode structure 22 has not yet been printed. For example, the solar cell 20 may include silicon material, and a dielectric layer, a front passivation layer, and a front anti-reflection layer sequentially formed on the front side of the silicon material, and a dielectric layer, a back passivation layer, and a back anti-reflection layer sequentially formed on the back side of the silicon material.

[0098] In related technologies, wire mesh printing involves weaving steel wires of a certain mesh count and diameter together to form a screen with a specific pattern. Based on the selective ink penetration principle of the resulting printing holes, a screen is created, and then printing is performed to form fixed grid lines on the semi-finished solar cell 21. However, because the steel wires are interwoven and not on the same plane, and the intersections can obstruct the printing holes, the ink cannot penetrate properly during printing, resulting in a low transfer rate and uneven printing, with problems such as broken grid lines, incomplete printing, and poor flatness. Furthermore, while a larger screen opening ratio results in better printability and a higher degree of fineness, the presence of knots in the wire mesh limits the flatness of the grid lines. Furthermore, even though current knotless printing screens can place the pattern opening between two parallel warp or weft lines to improve ink penetration, a large number of wide-arranged warp or weft lines still exist at the pattern opening. These lines, perpendicular to the pattern, still obstruct the printing of silver paste, resulting in uneven grid lines. This increases the resistivity of the printed electrode pattern, reduces the effective utilization of silver paste, and negatively impacts the power generation efficiency of the solar cells.

[0099] Therefore, in order to solve the above problems, in some embodiments, referring to FIG1, the screen printing structure 10 may include a first screen printing plate 11, the first screen printing plate 11 may include a substrate 110, the substrate 110 is provided with a plurality of sub-gate printing areas 111, the plurality of sub-gate printing areas 111 are spaced apart along a first direction X, and each sub-gate printing area 111 extends along a second direction Y. Wherein, the first direction X and the second direction Y intersect.

[0100] It should be noted that the sub-grid printing area 111 on the substrate 110 is unobstructed. Compared to the wire or mesh obstruction at the printing holes of wire mesh stencils in related technologies, the sub-grid printing area 111 on the substrate 110 can directly absorb the ink during printing. This allows for a smoother and more uniform ink absorption process, preventing printing defects such as broken sub-grids 221 or incomplete printing, and avoiding uneven ink distribution caused by obstruction. Furthermore, the direct opening method allows for a smaller width of the sub-grid printing area 111, enabling the printing of sub-grids 221 with narrower linewidths.

[0101] It is understood that the substrate 110 of the first screen printing plate 11 can be sheet-like, and the sub-grid printing area 111 can be a printing channel formed on the substrate 110 and extending through the thickness direction of the substrate 110, so that the paste can seep down onto the solar cell semi-finished product 21 through the sub-grid printing area 111. Specifically, during printing, the first screen printing plate 11 is set to correspond to the solar cell semi-finished product 21, paste is poured into one side of the substrate 110, a certain pressure is applied to the part of the substrate 110 with paste by a squeegee, and at the same time the squeegee moves toward the other side of the substrate 110, so that the paste can be squeezed from the sub-grid printing hole 111a onto the solar cell semi-finished product 21 by the squeegee during the movement, thereby realizing the printing of the sub-grid 221.

[0102] In this embodiment, the first direction X can be longitudinal, the second direction Y can be transverse, and multiple sub-gate printing areas 111 can be arranged longitudinally at intervals and parallel or approximately parallel. Each sub-gate printing area 111 is elongated and extends transversely.

[0103] Optionally, the substrate 110 can be a metal or polymer material substrate 110 or a substrate. When the substrate 110 is a metal substrate 110, it can be an alloy substrate, such as an iron sheet, a stainless steel sheet, or a nickel-cobalt-iron alloy sheet. When the substrate 110 is a polymer material substrate 110, it can be a polyimide (PI) sheet, a nylon substrate, etc.

[0104] Optionally, the first screen 11 may also include a frame that can be connected to the outer periphery of the substrate 110 for fixing the substrate 110.

[0105] Since the sub-gate printing area 111 is formed by opening a transverse and elongated opening on the substrate 110, when a large number of sub-gate printing areas 111 are opened on the substrate 110 to meet the requirement of the number of sub-gates 221, it will greatly damage the structural strength of the first screen 11, which may lead to the situation of screen bursting during printing. In order to improve the structural stability of the first screen 11, in some embodiments, referring to FIG3, each sub-gate printing area 111 may include a plurality of sub-gate printing holes 111a, which are spaced apart in the second direction Y. The plurality of sub-gate printing holes 111a in each sub-gate printing area 111 are configured to form a sub-gate 221 with a break 221a on the solar cell semi-finished product 21 (refer to FIG13). Dividing the sub-grid printing area 111 into spaced sub-grid printing holes 111a increases the structural strength of the first screen 11 when there are a large number of sub-grid printing areas 111, improves the mechanical structural stability of the first screen 11, thereby reducing the risk of the first screen 11 bursting during printing and thus improving the service life of the first screen 11.

[0106] As can be seen, by opening multiple sub-gate printing areas 111 on the substrate 110 of the first screen printing plate 11 and dividing each sub-gate printing area 111 into spaced sub-gate printing holes 111a, this application can print sub-gates 221 with narrower linewidths, obtain a low-wet-weight solar cell 20, and reduce printing defects such as broken grids, incomplete printing, and poor flatness of sub-gates 221. At the same time, it can also improve the structural stability of the first screen printing plate 11, thereby helping to extend the service life of the first screen printing plate 11.

[0107] Since the sub-grid 221 uses burn-through silver paste to etch the passivation layer and contact the silicon material, the collected current converges to the main grid 223 and is conducted through the solder ribbon or directly through the solder ribbon. The sub-grid 221 with a break 221a is formed on the solar cell semi-finished product 21 by the sub-grid printing holes 111a spaced apart on the first screen 11. In order not to affect the current transmission, referring to FIG2, in some embodiments, the screen structure 10 may also include a second screen 12. The second screen 12 is provided with a connecting printing area 121. The connecting printing area 121 is configured to form a connecting structure 222 located at the break 221a on the solar cell semi-finished product 21. The connecting structure 222 is configured to connect the sub-grids 221 located on both sides of the break 221a in the second direction Y.

[0108] It is understood that since the connection printing area 121 for forming the connection structure 222 on the solar cell semi-finished product 21 is set on another screen, the sub-grids 221 with the break 221a can be connected without affecting the structural strength of the first screen 11.

[0109] By setting a connecting printing area 121 on the second screen 12, the connecting structure 222 formed by the connecting printing area 121 is connected between the sub-grids 221 located on both sides of the break 221a, so that the sub-grids 221 with the break 221a on the surface of the solar cell semi-finished product 21 form continuous grid lines. In this way, the current is collected and transmitted through the sub-grids 221. Furthermore, when performing laser-induced sintering and IV (I-V curve test, photoelectric performance test) and EL (Electroluminescent test), the solar cell 20 can be powered on and tested as a whole without modifying the equipment, which is beneficial to improving the versatility of the measurement equipment.

[0110] The printed subgrid 221 uses a burn-through silver paste, typically a conductive paste with high corrosion resistance (e.g., silver paste), which can burn through the silicon nitride on the surface of the solar cell semi-finished product 21, allowing the conductive metal powder to contact the silicon material and form a conductive metal-silicon alloy to collect the current inside the solar cell 20. The paste used for the printed connection structure 222 can be either a non-burn-through silver paste or a burn-through silver paste. The non-burn-through silver paste has a lower degree of corrosion and will not damage the surface film layer of the solar cell 20, thus reducing damage to the PN junction of the solar cell 20.

[0111] In some embodiments, the sub-grid printing holes 111a can be formed on the first screen 11 using processes such as laser etching or electroplating, so that unobstructed printing holes are formed on the first screen 11. Correspondingly, the connecting printing area 121 provided on the second screen 12 can also be formed using processes such as laser etching or electroplating.

[0112] In some possible implementations, referring to FIG3, the width D1 of the sub-gate printed aperture 111a in the first direction X is 2μm to 30μm. Optionally, D1 can be 4μm to 20μm, for example, 8μm, 10μm or 18μm; or, D1 can be 4μm to 15μm, for example, 7μm, 12μm or 16μm; or, D1 can be 4μm to 11μm, for example, 6.5μm, 9μm or 10μm; or, D1 can be 4μm to 8μm, for example, 3μm, 5μm or 7μm; or, D1 can be 4μm to 6μm, for example, 2.5μm, 4μm or 6μm.

[0113] By limiting the width of the sub-grid printing hole 111a in the first direction X to a reasonable range, while ensuring the processing and forming of the first screen 11, the linewidth of the formed sub-grid 221 can be further narrowed. This helps reduce the wet weight of the conductive paste printing, reduces optical loss caused by linewidth obstruction, effectively reduces paste consumption, increases the light-receiving area of ​​the cell, and improves short-circuit current and on-state voltage. If D1 is less than 4μm, the width of the sub-grid printing hole 111a is too small, which not only requires high precision in the forming process of the first screen 11 and affects the printing difficulty, but also results in a small linewidth of the formed sub-grid 221, a reduced cross-sectional area of ​​the sub-grid 221, and an increase in contact resistance and line resistance, ultimately affecting the current transmission capability of the solar cell 20. If D1 is greater than 30μm, the linewidth of the formed sub-grid 221 increases, leading to increased paste consumption and affecting the light-receiving area of ​​the solar cell 20.

[0114] As can be seen, the screen structure 10 of this application is not only suitable for printing sub-grids 221 with a larger width (e.g., line width of 11μm, 13μm or 15μm), but also suitable for printing sub-grids 221 with a smaller width (e.g., line width of 7μm or less, such as 3μm, 4μm, 5μm or 6μm), thus making the screen structure 10 more widely applicable.

[0115] In some possible implementations, a gap region 111b is formed between two adjacent sub-gate printed holes 111a in the second direction Y. This gap region 111b refers to the substrate 110 body located between two adjacent sub-gate printed holes 111a, through which the paste will not seep down. It is evident that the gap region 111b is provided to disconnect the two adjacent sub-gate printed holes 111a, that is, the sub-gate printed area 111 is discontinuous, thereby avoiding the potential impact on the structural strength of the substrate 110 caused by the continuity of the sub-gate printed area 111.

[0116] Optionally, the length of the sub-grid printing hole 111a in the second direction Y is D2, and the width of the spacing region 111b in the second direction Y is D3, with D2 / D3 ranging from 25 to 240. For example, it can be 60, 80, 100, etc. By limiting the ratio of the length of the sub-grid printing hole 111a in the second direction Y to the width of the spacing region 111b in the second direction Y to a reasonable range, the specifications of the formed sub-grid 221 can be met, while ensuring that the first screen 11 has reasonable structural strength, thereby greatly guaranteeing the lifespan of the first screen 11.

[0117] In some embodiments, the length D2 of the secondary gate printed hole 111a in the second direction Y is 5mm to 30mm. Optionally, D2 can be 5mm to 20mm, for example, 8mm, 10mm or 18mm; or, D2 can be 5mm to 15mm, for example, 11mm, 12mm or 13mm; or, D2 can be 5mm to 10mm, for example, 6mm, 7mm or 9mm.

[0118] In some implementations, the width of the interval 111b in the second direction Y, D3, is 0.05mm to 1.5mm. Optionally, D3 can be 0.05mm to 1.2mm, for example, 0.2mm, 0.7mm, or 1mm; or D3 can be 0.05mm to 1.0mm, for example, 0.3mm, 0.6mm, or 0.8mm; or D3 can be 0.05mm to 0.6mm, for example, 0.1mm, 0.4mm, or 0.5mm.

[0119] By limiting the dimensions of the sub-grid printing holes 111a and the spacing area 111b in the second direction Y, the structural stability of the first screen 11 is satisfied while the aperture ratio of the substrate 110 of the first screen 11 is made larger, which effectively ensures the transmission of the paste and makes the grid line effect after printing better. Thus, the first screen 11 has the dual advantages of structural stability and paste transmission.

[0120] In some embodiments, the connecting printing area 121 can be a rectangular printing hole, which can be configured to make the connecting structure 222 formed on the solar cell semi-finished product 21 rectangular. The rectangular connecting structure 222 connects between the sub-gates 221 located on both sides of the break 221a, such that each sub-gate 221 forms an uninterrupted gate line in the second direction Y.

[0121] Of course, in other embodiments, the connecting printing area 121 may also be, for example, a circular printing hole, a near-circular printing hole, or other polygonal holes (e.g., triangular, pentagonal, or hexagonal, etc.).

[0122] Furthermore, in some embodiments, referring to Figures 4 and 15, the connection printing area 121 may include a first connection printing hole 1211, a second connection printing hole 1212, and an intermediate connection printing hole 1213. The intermediate connection printing hole 1213 communicates between the first connection printing hole 1211 and the second connection printing hole 1212. The first connection printing hole 1211 is configured to form a first connection line 2221 on the solar cell semi-finished product 21, and the first connection line 2221 is connected to the sub-gate 221 located on one side of the break 221a in the second direction Y. The second connection printing hole 1212 is configured to form a second connection line 2222 on the solar cell semi-finished product 21, and the second connection line 2222 is connected to the sub-gate 221 located on the other side of the break 221a in the second direction Y. The intermediate connection printing hole 1213 is configured to form an intermediate connection line 2223 on the solar cell semi-finished product 21, and the intermediate connection line 2223 is connected between the first connection line 2221 and the second connection line 2222.

[0123] Compared to the relatively regular rectangle of the connecting printing area 121, this configuration allows the first connecting line 2221 formed through the first connecting printing hole 1211 to connect to the sub-gate 221 located on one side of the break 221a, and the second connecting line 2222 formed through the second connecting printing hole 1212 to connect to the sub-gate 221 located on the other side of the break 221a. The intermediate connecting line 2223 formed through the intermediate connecting printing hole 1213 connects between the first connecting line 2221 and the second connecting line 2222. This enables the sub-gate 221 with the break 221a to form a continuous sub-gate 221, thereby achieving the current transmission function while reducing the amount of paste used, reducing the wet weight of the printing paste, and reducing the manufacturing cost of the solar cell 20.

[0124] It should be noted that the first connecting printing hole 1211, the second connecting printing hole 1212, and the intermediate connecting printing hole 1213 are interconnected to form the connecting printing area 121. Furthermore, the first connecting printing hole 1211 and the second connecting printing hole 1212 can extend along the first direction X. The shapes of the first connecting printing hole 1211, the second connecting printing hole 1212, and the intermediate connecting printing hole 1213 can be different. The width of the intermediate connecting printing hole 1213 in the first direction X can be smaller than the width of the first connecting printing hole 1211 and the second connecting printing hole 1212 in the first direction X. Alternatively, the width of the intermediate connecting printing hole 1213 in the first direction X can gradually change from the first connecting printing hole 1211 towards the second connecting printing hole 1212, making the connecting printing holes non-rectangular, non-trapezoidal, or other shapes with a large opening area. This avoids forming a connecting structure 222 on the solar cell semi-finished product 21 that consumes excessive paste.

[0125] In some possible implementations, in order to improve the fault tolerance of the connection between the sub-gates 221 on both sides of the break 221a, that is, to facilitate the connection between the sub-gates 221 on both sides of the break 221a and the connecting structure 222, the width of the sub-gate printing hole 111a in the first direction X is D1, and the shortest length of the first connecting printing hole 1211 and the second connecting printing hole 1212 in the first direction X is D4, where D4 ≥ D1. By limiting the length of the first connecting printing hole 1211 and the second connecting printing hole 1212 in the first direction X to be greater than the width of the sub-gate printing hole 111a in the first direction X, that is, during printing, a sufficiently large connection area can be provided to stably connect with the sub-gate 221. During the formation of the connecting structure 222, the connection offset of the first connecting line 2221 and the second connecting line 2222 can be controlled, improving the finished product defects caused by offset.

[0126] It should be noted that the shortest length D4 of the first connecting printed hole 1211 and the second connecting printed hole 1212 in the first direction X means that the lengths of the first connecting printed hole 1211 and the second connecting printed hole 1212 in the first direction X can be equal, or the length of the first connecting printed hole 1211 in the first direction X is greater than the length of the second connecting printed hole 1212 in the first direction X, or the length of the first connecting printed hole 1211 in the first direction X is less than the length of the second connecting printed hole 1212 in the first direction X.

[0127] In some possible implementations, the length D5 of the connecting printing area 121 in the second direction Y is 0.05mm to 1.5mm. Optionally, D5 can be 0.1mm to 1.2mm, 0.1mm to 1.0mm, or 0.1mm to 0.8mm, for example, 0.5mm, 1.0mm, or 1.2mm. Since the connecting structure 222 formed by the connecting printing area 121 needs to be located at the break 221a so that it can connect between the grid lines located on both sides of the break 221a, by limiting the overall length of the connecting printing area 121 to accommodate the width of the spacing area 111b in the second direction Y, the connecting structure 222 can have an offset allowance in the second direction Y, reducing printing difficulty and thus reducing printing defects caused by grid breakage due to offset.

[0128] In some embodiments, the shortest length D4 of the first connecting printed hole 1211 and the second connecting printed hole 1212 in the first direction X is 20μm to 200μm. Optionally, D4 can be 20μm to 180μm, 20μm to 150μm, or 20μm to 80μm, for example, it can be 50μm, 80μm, or 100μm. By limiting the range of D4, a certain offset is reserved when printing the connecting line, which can reduce the printing difficulty.

[0129] In some embodiments, the width D6 of the first connecting printed hole 1211 and the second connecting printed hole 1212 in the second direction Y is 10μm to 200μm. Optionally, D6 can be 10μm to 150μm, 10μm to 100μm, or 10μm to 60μm, for example, 40μm, 80μm, or 120μm. By limiting the range of D6, the amount of paste used can be reduced while still allowing the connecting structure 222 to be connected to the sub-gate 221.

[0130] In some embodiments, the width D7 of the intermediate connecting printed hole 1213 in the first direction X is 10 μm to 200 μm. Optionally, D7 can be 10 μm to 150 μm, 10 μm to 100 μm, or 10 μm to 60 μm, for example, 40 μm, 80 μm, or 120 μm. By limiting the range of D7, while ensuring that the formed intermediate line is effectively connected between the first connecting line 2221 and the second connecting line 2222, the amount of paste used can be reduced, the wet weight can be reduced, and the light-blocking area can be reduced.

[0131] It can be seen that by limiting the range of D4, D6, and D7, a certain offset can be reserved to provide a sufficiently large connection area for stable connection with the sub-gate 221, while also avoiding the situation where excessive paste usage and increased material costs are caused by the excessive size of the first connection printing hole 1211 and the second connection printing hole 1212.

[0132] In some possible implementations, referring to Figures 5a to 5c, the shape of the connecting printing area 121 includes at least one of H-shape, N-shape, or inverted figure-eight shape. It is understood that the second screen 12 may have multiple connecting printing areas 121, which may have the same shape or different shapes. Using connecting printing areas 121 with these shapes can reduce paste loss while ensuring effective connection between the connecting structure 222 and the sub-grids 221 located on both sides of the break 221a.

[0133] In one example, the width of the intermediate connecting printing hole 1213 in the first direction X can be less than the shortest length of the first connecting printing hole 1211 and the second connecting printing hole 1212 in the first direction X, making the shape of the intermediate connecting printing hole 1213 rectangular. The first connecting printing hole 1211 and the second connecting printing hole 1212 can have the same shape and size, both being rectangular, thus making the overall shape of the connecting printing area 121 H-shaped. This configuration, on the one hand, provides a symmetrical and regular shape that facilitates the processing of the second screen 12; on the other hand, it ensures that when the first connecting line 2221 and the second connecting line 2222 formed on the solar cell semi-finished product 21 are connected to the sub-grid 221, even with offset errors, the connection between the sub-grid 221 and the connecting line can be guaranteed. This allows the connecting structure 222 to effectively connect the sub-grids 221 located on both sides of the break 221a, and reduces paste loss, thus helping to reduce costs.

[0134] In another example, the width of the intermediate connecting printing hole 1213 in the first direction X can be less than the shortest length of the first connecting printing hole 1211 and the second connecting printing hole 1212 in the first direction X, making the shape of the intermediate connecting printing hole 1213 rectangular. The first connecting printing hole 1211 and the second connecting printing hole 1212 can have the same shape, both being rectangular, but the lengths of the first connecting printing hole 1211 and the second connecting printing hole 1212 in the first direction X are not equal, making the overall shape of the connecting printing area 121 an inverted I-shape. This setting can also ensure the effective connection between the connecting structure 222 and the sub-grid 221, and can reduce the loss of paste, thereby helping to reduce costs.

[0135] In another example, the width of the intermediate connecting printing hole 1213 in the first direction X can also be less than the shortest length of the first connecting printing hole 1211 and the second connecting printing hole 1212 in the first direction X. However, the intermediate connecting printing hole 1213 is connected between the first connecting printing hole 1211 and the second connecting printing hole 1212 in an inclined manner, so that the connecting printing area 121 presents a parallelogram. The first connecting printing hole 1211 and the second connecting printing hole 1212 can have the same shape and size, so that the overall shape of the connecting printing area 121 is N-shaped. This also enables the connecting structure 222 formed by the connecting printing area 121 to be effectively connected between the sub-grids 221 located on both sides of the break 221a, and can reduce the loss of slurry.

[0136] Of course, in other embodiments, the width of the intermediate connecting printing hole 1213 in the first direction X can be set to be gradually changing from the first connecting printing hole 1211 to the second connecting printing hole 1212, for example, it can be smaller and then larger, and the overall shape of the connecting printing area 121 can be an inverted figure 8.

[0137] Preferably, the shape of the connecting printing area 121 is H-shaped, which not only makes it easier to process and form from the perspective of the second screen 12, but also makes it easier to ensure the connection between the formed connecting structure 222 and the sub-grid 221 from the printing perspective, thereby reducing paste loss.

[0138] It should also be noted that the connection position of the intermediate connection printing hole 1213 in the connection printing area 121 in the above examples can be offset in the second direction Y, as long as the formed intermediate connection line 2223 can be connected between the first connection line 2221 and the second connection line 2222, so that the sub-gate 221 can ensure current transmission. This can effectively improve the design flexibility of the connection printing area 121.

[0139] It is understood that the screen printing structure 10 in this embodiment can be applied to OBB (OBusbar, no main busbar), MBB (Multi Busbar, multiple main busbars), SMBB (Super Multi Busbar, super multi busbars), etc. OBB technology eliminates the main busbar 223 in the printing process, using finer solder strips to directly replace and connect the sub-busbars 221 to collect and conduct current. This significantly reduces the metal shading area on the surface of the solar cell semi-finished product 21, increases the light-receiving area, and thus improves the power generation efficiency of the solar cell 20. MBB and SMBB technologies primarily collect the current from the sub-busbars 221 through the main busbar 223 and conduct the current through solder strips.

[0140] When using OBB technology, i.e., a solar cell 20 without a main grid 223, as an example, the second screen 12 does not have a main grid printing area 122. In the second direction Y, a spacer area 111b is formed between two adjacent sub-grid printing holes 111a. The length of the sub-grid printing hole 111a in the second direction Y is D2, the width of the spacer area 111b in the second direction Y is D3, and the number of spacer areas 111b is M. The aperture ratio of the first screen 11 is F, F = D2(M+1) / [D2(M+1)+D3*M], 90%≤F<100%. For example, the width of the spacer area 111b is designed to be 0.2mm, and the number is 17. The total length of all the sub-grid printing holes 111a and spacer areas 111b on each sub-grid printing area 111 is 208.6mm, then its aperture ratio is (208.6-0.2*17) / 208.6*100% = 98.37%.

[0141] When the main grid printing area 122 is not set on the second screen 12 to form a main gridless solar cell 20, by limiting the length of the sub-grid printing hole 111a, the width of the interval area 111b, and the number of interval areas 111b, the ratio of the size of the interval area 111b to the total length of the sub-grid printing area 111 can be controlled. On the basis of ensuring smooth and uniform slurry seepage, the sub-grid printing area 111 can be segmented more reasonably, effectively ensuring the structural stability of the first screen 11.

[0142] Since OBB technology involves directly welding the solder strip to the relatively thin sub-grid 221, problems such as broken grids, open welds, and incomplete welds are prone to occur during welding. Therefore, in some embodiments, the second screen 12 may have a main grid printing area 122, configured to form the main grid 223 on the solar cell semi-finished product 21. Referring to Figure 6, by also providing a main grid printing area 122 on the second screen 12 to form the main grid 223 on the solar cell semi-finished product 21, the current formed by collecting charge carriers through the sub-grid 221 is concentrated on the main grid 223, and then welded to the solder strip through the main grid 223 to conduct the current, effectively ensuring the welding area between the solder strip and the main grid 223.

[0143] Optionally, the main grid printing area 122 is spaced apart from the connecting printing area 121 in the second direction Y, and / or the connecting printing area 121 is at least partially connected to the main grid printing area 122.

[0144] In one example, the main grid printing area 122 is spaced apart from the connecting printing area 121 in the second direction Y. Since the connecting structure 222 formed by the connecting printing area 121 is located at the break 221a of the sub-grid 221, this arrangement allows the break 221a on the solar cell semi-finished product 21 to also be spaced apart from the main grid 223, and the connecting structure 222 located at the break 221a is spaced apart from the main grid 223.

[0145] In this way, the break 221a and the main gate 223 do not affect each other. By setting the connecting structure 222 at the break 221a and connecting it between the secondary gates 221 located on both sides of the break 221a, the current can be transmitted through the secondary gates 221, so that the current can be normally converged on the main gate 223.

[0146] In another example, the connecting printing area 121 is at least partially connected to the main grid printing area 122. Since the connecting structure 222 formed by the connecting printing area 121 is located at the break 221a of the sub-grid 221, this arrangement makes the main grid 223 intersect with the break 221a of the sub-grid 221. In this case, the connecting structure 222 located at the break 221a is also connected to the main grid 223.

[0147] This method utilizes the connecting structure 222 at the break 221a to strengthen the connection between the main grid 223 and the secondary grid 221. However, it should be noted that this method places requirements on the dimensions of the connecting structure 222. Specifically, since the connecting structure 222 is printed simultaneously with the main grid 223 and uses the same printing paste as the main grid 223, the final connecting structure 222 has a lower line height, which may lead to grid breakage during welding.

[0148] In another example, the main grid printing area 122 is spaced apart from a portion of the connecting printing area 121 in the second direction Y, and the other portion of the connecting printing area 121 is at least partially connected to the main grid printing area 122. That is, a portion of the break 221a on the solar cell semi-finished product 21 is spaced apart from the main grid 223, and another portion of the break 221a intersects with the main grid 223. It is understood that in this example, the connection structure 222 formed by the connecting printing areas 121 spaced apart from the main grid printing area 122 can be the same as or different from the connection structure 222 formed by the connecting printing areas 121 connected to the main grid printing area 122. For example, the connecting printing area 121, which is spaced apart from the main grid printing area 122, has a connecting structure 222 that connects the sub-grid 221 with a break 221a. As long as the connection is satisfied, the size (width, length, height, etc.) of the corresponding connecting printing area 121 can be set smaller to reduce paste loss. However, the connecting printing area 121, which is connected to the main grid printing area 122, needs to meet the requirements of connecting the broken sub-grid 221, as well as the current convergence and welding requirements. Therefore, the size of the connecting printing area 121 needs to be set larger so that the size of the connecting structure 222 meets the above requirements. This avoids the situation where the grid breaks due to the reaction between the solder strip and the conductive metal powder (such as silver powder) contained in the sub-grid 221 during welding.

[0149] For example, there can be three main grid printing areas 122 and two columns of connecting printing areas 121. One column of connecting printing areas 121 is located between two columns of main grid printing areas 122, and at least a portion of the other column of connecting printing areas 121 is connected to the last column of main grid printing areas 122. Accordingly, there are three main grids 223 and two columns of connecting structures 222. One column is located between two main grids 223, and the other column of connecting structures 222 is located on the last main grid 223.

[0150] In some possible implementations, the number of main grid printing areas 122 is N. In the second direction Y, a spacing region 111b is formed between two adjacent sub-grid printing holes 111a. The number M of spacing regions 111b in each sub-grid printing area 111 is: 1 / 10N≤M≤20N; where N is an integer and N≥1, and M is an integer. Optionally, the number M of spacing regions 111b can be 1N≤M≤20N, 5N≤M≤20N, or 10N≤M≤20N, etc. For example, when the number of main grid printing areas 122 is 10, the number M of spacing regions 111b is: 1≤M≤200, for example, it can be 10, 20, or 30, etc. By establishing a relationship between the number of main grid printing areas 122 on the second screen 12 and the number of interval areas 111b on the first screen 11, that is, by establishing a relationship between the number of main grids 223 formed on the solar cell semi-finished product 21 and the number of breaks 221a, while taking into account the structural strength of the first screen 11 and achieving continuous connection of the sub-grids 221, the number of main grids 223 can be reduced, the amount of paste used can be reduced, and the light-shielding area can be reduced.

[0151] Optionally, the main grid printing area 122 includes multiple main grid printing areas 122, which are spaced apart along the second direction Y. When the main grid printing areas 122 are spaced apart from the connecting printing areas 121 in the second direction Y, the connecting printing areas 121 are located between two adjacent main grid printing areas 122. Since a reasonable increase in the number of main grids 223 can reduce the transmission distance of the sub-grids 221, this application sets multiple main grid printing areas 122 so that multiple main grids 223 are formed on the solar cell semi-finished product 21, thereby shortening the distance of the sub-grids 221 between two connected main grids 223, thereby reducing the grid line transmission resistance and reducing the series resistance, which is beneficial to improving the photoelectric conversion efficiency.

[0152] In this embodiment, SMBB technology can be used, and the number of main grid printing areas 122 can be 16 to 26. For example, if the number of main grid printing areas 122 is 16, 18, 22 or 24, more main grids 223 with smaller spacing can be obtained.

[0153] It should be noted that the sub-grid 221 is mainly for collecting current. The connection printing area 121 is located between two adjacent main grid printing areas 122, meaning the break 221a is located between two adjacent main grids 223, making each sub-grid 221 an independent region. During laser-induced sintering, the surface of the solar cell 20 needs to be energized before laser-induced sintering. If there is a break 221a between the sub-grids 221, the entire cell cannot be energized, making the process impossible. Furthermore, the IV and EL testing machines used in production lines typically use probes, and the probe pressing position is mainly on the main grid 223, and not every main grid 223 has one. Therefore, current mass-production IV and EL testing machines and laser-induced sintering equipment cannot be used, requiring modification. Therefore, the connection structure 222 improves the energizing situation of laser-induced sintering while also improving the current transmission method, achieving versatility without changing the current testing equipment.

[0154] In some embodiments, referring to FIG6, when the main grid printing area 122 is spaced apart from the connecting printing area 121 in the second direction Y, the second screen 12 is also provided with a main grid overlapping printing area 123. The main grid overlapping printing area 123 is at least partially located on the main grid printing area 122 and communicates with the main grid printing area 122. The main grid overlapping printing area 123 is configured to form a main grid overlapping structure 224 at the intersection of the main grid 223 and the sub-grid 221 on the solar cell semi-finished product 21. With this configuration, the main grid overlapping printing area 123 on the second screen 12 forms a main grid overlapping structure 224 at the intersection of the main grid 223 and the sub-grid 221, which can be used to collect the photocurrent generated by the solar cell 20 when receiving light. It can also strengthen the connection between the main grid 223 and the sub-grid 221, further ensuring good contact between the main grid 223 and the sub-grid 221 while reducing metal recombination, effectively reducing metal resistance, improving current transmission, and thus improving cell efficiency. Meanwhile, the main grid overlap structure 224 is formed on the second screen plate 12, so that its structural strength is not affected by being formed on the first screen plate 11, which is conducive to greatly improving the life of the first screen plate 11.

[0155] Because the main grid overlap printing area 123 is set on the second screen 12, the main grid overlap structure 224 is printed synchronously with the main grid 223. Compared with the synchronous printing with the sub-grid 221, the height of the main grid overlap structure 224 will be reduced, for example, from 7μm to 4μm. This will greatly increase the risk of grid breakage during subsequent welding. In addition, the material used for soldering will react with the silver in the main grid 223 and the sub-grid 221, causing the silver at the junction of the main grid 223 and the sub-grid 221 to be reacted off, which will also result in grid breakage.

[0156] Based on the above problems, in some possible embodiments, referring to Figures 3 to 7, the substrate 110 further includes a sub-gate overlap printing area 112. The sub-gate overlap printing area 112 is at least partially located on the sub-gate printing area 111 and communicates with the sub-gate printing hole 111a. The sub-gate overlap printing area 112 is configured to form a sub-gate overlap structure 225 on the solar cell semi-finished product 21, and the sub-gate overlap structure 225 at least partially overlaps with the main gate overlap structure 224. By printing the main gate overlap structure 224 and the sub-gate overlap structure 225 respectively during the printing of the main gate 223 and the sub-gate 221, making them at least partially overlapped, the height of the overlap structure at the intersection of the main gate 223 and the sub-gate 221 can be further increased. This reduces the risk of gate breakage due to the reduced height of the overlap structure at the intersection of the main gate 223 and the sub-gate 221 caused by low wet weight, thereby improving the welding effect.

[0157] Optionally, the main grid overlap structure 224 covers the sub-grid overlap structure 225, that is, the projection of the sub-grid overlap structure 225 on the solar cell semi-finished product 21 falls within the projection range of the main grid overlap structure 224 on the solar cell semi-finished product 21. Alternatively, the sub-grid overlap structure 225 covers the main grid overlap structure 224, that is, the projection of the main grid overlap structure 224 on the solar cell semi-finished product 21 falls within the projection range of the sub-grid overlap structure 225 on the solar cell semi-finished product 21.

[0158] It is understandable that by designing the size and position of the sub-gate overlap printing area 112 on the substrate 110 and the main gate overlap printing area 123 on the second screen 12, the degree of overlap between the main gate overlap structure 224 and the sub-gate overlap structure 225 can be controlled. By setting the main gate overlap structure 224 to cover the sub-gate overlap structure 225 or the sub-gate overlap structure 225 to cover the main gate overlap structure 224, on the one hand, the overlap structure area formed by overlap can be larger, which means that a larger area has a higher height, thus making it more conducive to meeting welding requirements; on the other hand, since the paste will diffuse to a certain extent after printing, this form of covering is beneficial to the aesthetics of the appearance.

[0159] Referring to Figures 7 and 8, when the main gate overlap structure 224 covers the secondary gate overlap structure 225, the maximum width T1 of the main gate overlap printing area 123 in the first direction X is 30μm to 80μm. Optionally, T1 can be 40μm to 70μm, 40μm to 60μm, or 40μm to 50μm, for example, it can be 50μm, 60μm, or 70μm.

[0160] The minimum width T2 of the main grid overlap printing area 123 in the first direction X is 13μm to 80μm. Optionally, T2 can be 13μm to 25μm, 25μm to 45μm, 45μm to 60μm, or 60μm to 80μm, for example, it can be 15μm, 25μm, 40μm, 60μm, or 80μm.

[0161] The length T3 of the main grid overlap printing area 123 in the second direction Y is 0.6mm to 1.6mm. Optionally, T3 can be 0.6mm to 1.4mm, 0.6mm to 1.2mm, or 0.6mm to 1.0mm, for example, it can be 0.7mm, 1.0mm, or 1.3mm.

[0162] The maximum width T4 of the sub-gate overlap printing area 112 in the first direction X is 15μm to 70μm. Optionally, T4 can be 15μm to 60μm, 15μm to 50μm, or 15μm to 40μm, for example, it can be 45μm, 55μm, or 65μm.

[0163] The minimum width T5 of the sub-gate overlap printing area 112 in the first direction X is 10μm to 70μm. Optionally, T5 can be 10μm to 20μm, 10μm to 30μm, or 15μm to 30μm, for example, it can be 16μm, 20μm, or 24μm.

[0164] The length T6 of the sub-gate overlap printing area 112 in the second direction Y is 0.5mm to 1.5mm. Optionally, T6 can be 0.5mm to 1.3mm, 0.5mm to 1.1mm, or 0.5mm to 0.8mm, for example, it can be 0.6mm, 0.8mm, or 1.2mm.

[0165] When the main gate overlap structure 224 covers the sub-gate overlap structure 225, by limiting the size of the main gate overlap printing area 123 and the sub-gate overlap printing area 112 to be within a reasonable range, it can prevent the printing grid from being broken due to the huge difference in width and height from the main gate 223 to the sub-gate 221 during printing, while ensuring sufficient area to meet the welding needs, and preventing the sub-gate 221 from being broken due to the melting of solder after welding.

[0166] It is understandable that the widths of the main gate overlap structure 224 and the sub-gate overlap structure 225 are gradually varied along the second direction Y. Controlling the minimum width ensures a stable connection between the sub-gate 221b and the main gate 223, preventing breakage. Controlling the maximum width allows for a larger area to collect current, maximizing the conduction current and reducing conduction resistance, thus facilitating effective contact and stable current transmission. Simultaneously, setting the size of the printing area of ​​the main gate overlap structure 224 to be compatible with the size of the sub-gate overlap printing area 112 allows for a certain offset allowance when the sub-gate overlap structure 225 falls within the range of the main gate overlap structure 224, avoiding a poor overall appearance of the overlap structure.

[0167] Accordingly, when the sub-gate overlap structure 225 covers the main gate overlap structure 224, the maximum width T1 of the main gate overlap printing area 123 in the first direction X is 15μm to 70μm. Optionally, T1 can be 15μm to 60μm, 15μm to 50μm, or 15μm to 40μm, for example, it can be 20μm, 30μm, or 60μm.

[0168] The minimum width T2 of the main grid overlap printing area 123 in the first direction X is 10μm to 70μm. Optionally, T2 can be 10μm to 40μm, 10μm to 50μm, or 10μm to 60μm, for example, it can be 20μm, 30μm, or 40μm.

[0169] The length T3 of the main grid overlap printing area 123 in the second direction Y is 0.5mm to 1.5mm. Optionally, T3 can be 0.5mm to 1.3mm, 0.5mm to 1.1mm, or 0.5mm to 0.8mm, for example, it can be 0.6mm, 0.8mm, or 1.2mm.

[0170] The maximum width T4 of the sub-gate overlap printing area 112 in the first direction X is 30μm to 80μm. Optionally, T4 can be 30μm to 70μm, 30μm to 60μm, or 30μm to 50μm, for example, it can be 40μm, 60μm, or 70μm.

[0171] The minimum width T5 of the sub-gate overlap printing area 112 in the first direction X is 13μm to 80μm. Optionally, T5 can be 13μm to 23μm, 13μm to 40μm, or 13μm to 60μm, for example, it can be 20μm, 40μm, or 60μm.

[0172] The length T6 of the sub-gate overlap printing area 112 in the second direction Y is 0.6mm to 1.6mm. Optionally, T6 can be 0.6mm to 1.4mm, 0.6mm to 1.2mm, or 0.6mm to 1.0mm, for example, it can be 0.7mm, 1.0mm, or 1.3mm.

[0173] When the sub-gate overlap structure 225 covers the main gate overlap structure 224, by limiting the size of the sub-gate overlap printing area 112 and the main gate overlap printing area 123 to be within a reasonable range, it can prevent the printing grid from being broken due to the huge difference in width and height from the main gate 223 to the sub-gate 221 during printing, while ensuring sufficient area to meet the welding needs, and preventing the sub-gate 221 from being broken due to the melting of solder after welding.

[0174] It is understandable that the widths of the main gate overlap structure 224 and the sub-gate overlap structure 225 are gradually varied along the second direction Y. Controlling the minimum width ensures a stable connection between the sub-gate 221b and the main gate 223, preventing breakage. Controlling the maximum width allows for a larger area to collect current, maximizing the conduction current and reducing conduction resistance, thus facilitating effective contact and stable current transmission. Simultaneously, setting the size of the printing area of ​​the main gate overlap structure 224 to be compatible with the size of the sub-gate overlap printing area 112 allows for a certain offset allowance when the sub-gate overlap structure 225 falls within the range of the main gate overlap structure 224, preventing a poor overall appearance of the overlap structure.

[0175] Referring to Figures 9 to 11, in a second aspect, this application also discloses a screen printing structure 10, which may include a first screen 11 and a second screen 12. A plurality of sub-grid printing areas 111 may be disposed on the first screen 11, the plurality of sub-grid printing areas 111 being spaced apart along a first direction X and extending along a second direction Y. The sub-grid printing areas 111 can be used to form sub-grids 221 on the solar cell semi-finished product 21 during printing, wherein the first direction X intersects the second direction Y.

[0176] The second screen printing plate 12 may be provided with a main grid printing area 122, which can be used to form the main grid 223 during the printing of the solar cell semi-finished product 21.

[0177] Optionally, a sub-grid overlap printing area 112 may be provided on the first screen 11, and a main grid overlap printing area 123 may be provided on the second screen 12. The sub-grid overlap printing area 112 is at least partially located on the sub-grid printing area 111 and communicates with the sub-grid printing hole 111a. The sub-grid overlap printing area 112 is configured to form a sub-grid overlap structure 225 on the solar cell semi-finished product 21. The main grid overlap printing area 123 is at least partially located on the main grid printing area 122 and communicates with the main grid printing area 122. The main grid overlap printing area 123 is configured to form a main grid overlap structure 224 located at the intersection of the main grid 223 and the sub-grid 221 on the solar cell semi-finished product 21, and the main grid overlap structure 224 and the sub-grid overlap structure 225 are at least partially overlapped. This configuration increases the height of the overlap structure at the intersection of the main gate 223 and the secondary gate 221, which can reduce the risk of gate breakage caused by the reduced height of the overlap structure at the intersection of the main gate 223 and the secondary gate 221 due to low wet weight, thereby improving the welding effect.

[0178] It is understood that the sub-grid printing area 111 on the first screen 11 of the screen structure 10 may also include a plurality of sub-grid printing holes 111a. The plurality of sub-grid printing holes 111a are spaced apart in the second direction Y. The plurality of sub-grid printing holes 111a in each sub-grid printing area 111 are configured to form a sub-grid 221 with a break 221a on the solar cell semi-finished product 21. This enables the printing of sub-grids 221 with narrower linewidths, resulting in a low-wet-weight solar cell 20. It also reduces printing defects such as broken grids, incomplete printing, and poor flatness of the sub-grids 221, while improving the structural stability of the first screen 11, thereby helping to extend the service life of the first screen 11.

[0179] Correspondingly, a connecting printing area 121 may also be provided on the second screen 12. The connecting printing area 121 is configured to form a connecting structure 222 on the solar cell semi-finished product 21 located at the break 221a. The connecting structure 222 is configured to connect the sub-grids 221 located on both sides of the break 221a in the second direction Y.

[0180] It is understood that the structure of the sub-gate printing area 111, the sub-gate printing hole 111a, the main gate printing area 122, the connecting printing area 121, the sub-gate overlapping printing area 112, and the main gate overlapping printing area 123, etc., can be referred to the description in the first aspect above, and will not be repeated here.

[0181] Thirdly, this application also discloses a solar cell 20. Referring to Figures 12 and 13, the solar cell 20 may include a solar cell semi-finished product 21 and an electrode structure 22.

[0182] In this application, the electrode structure 22 can be disposed on the front side of the solar cell semi-finished product 21, on the back side of the solar cell semi-finished product 21, or on both sides.

[0183] In this application, the electrode structure 22 is disposed on the front side of the solar cell semi-finished product 21, that is, the electrode structure 22 of this application is a front electrode. The following description will take the example of the electrode structure 22 being disposed on the front side of the solar cell semi-finished product 21.

[0184] In some embodiments, the electrode structure 22 may include a plurality of sub-gates 221, which are spaced apart along a first direction X, and each sub-gate 221 extends along a second direction Y.

[0185] Since the sub-busbar 221 can achieve effective current transmission while obtaining a low-wet-weight solar cell and reducing surface shading and conductive paste consumption, it is of great significance for reducing the overall manufacturing cost of the solar cell 20.

[0186] In some embodiments, each sub-gate 221 includes multiple sub-gates 221b, which are spaced apart in the second direction Y to form a break 221a between adjacent sub-gates 221b. This arrangement can reduce surface shading and conductive paste consumption without affecting the current collection of the sub-gate 221.

[0187] To avoid affecting current transmission, in some embodiments, the electrode structure 22 may further include a connection structure 222. The connection structure 222 is located at the break 221a and is connected between two adjacent sub-gates 221b in the second direction Y. By providing the connection structure 222 at the break 221a and connecting it between the sub-gates 221 located on both sides of the break 221a, current can be transmitted through the sub-gates 221, thus realizing the current transmission function of the sub-gates 221.

[0188] In some embodiments, referring to FIG14, the width W1 of the sub-gate 221 in the first direction X is 4μm to 30μm. Optionally, W1 can be 4μm to 20μm, for example, 8μm, 10μm or 14μm; or, W1 can be 4μm to 10μm, for example, 5μm, 7μm or 9μm. By limiting the range of the width W1 of the sub-gate 221 in the first direction X, the sub-gate 221 is narrowed, resulting in a low-wet-weight solar cell 20 and reducing the manufacturing cost of the solar cell 20.

[0189] In some embodiments, the height H of the cross-section of the sub-gate 221 is 1 μm to 10 μm. Optionally, H can be 1 μm to 8 μm, 1 μm to 6 μm, or 1 μm to 4 μm, for example, 2 μm, 6 μm, or 8 μm. By limiting the height H of the cross-section of the sub-gate 221, the cross-sectional area of ​​the sub-gate 221 can be better controlled, resulting in better current transmission capability. If the height of the cross-section is too low, the contact resistance and line resistance of the sub-gate 221 will increase, ultimately affecting the transmission capability of the solar cell 20.

[0190] In some embodiments, the smoothing factor of the sub-gate 221 in the height direction is less than or equal to 1. Optionally, the smoothing factor can be 0.01 to 1, 0.01 to 0.8, or 0.1 to 0.3, for example, it can be 0.02, 0.06, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0. As can be seen from Figures 21 and 22, the sub-gate 221 printed using the first screen 11 of this application can have better smoothness, and the height profile curve of the sub-gate 221 is smoother. Therefore, the resistance of the sub-gate 221 is smaller, and the loss during current transmission is reduced, thereby improving the output power and efficiency of the solar cell 20. Furthermore, the relatively flat sub-gate 221 can ensure smoother current transmission, reduce losses during current transmission, and further improve the performance of the solar cell 20.

[0191] In some embodiments, the connection structure 222 can be a rectangular connection structure 222, the area of ​​which is filled with slurry. The rectangular connection structure 222 is connected between the sub-gates 221b located on both sides of the break 221a, such that each sub-gate 221 extends into a continuous gate line in the second direction Y.

[0192] Of course, in other embodiments, the connection structure 222 may also be, for example, circular, near-circular, or other polygonal holes (e.g., triangular, pentagonal, or hexagonal).

[0193] In addition, in some embodiments, referring to FIG15, the connection structure 222 may include a first connection line 2221, a second connection line 2222, and an intermediate connection line 2223. The first connection line 2221 is connected to one of the sub-gates 221b located on one side of the break 221a in the second direction Y. The second connection line 2222 is connected to another sub-gate 221b located on the other side of the break 221a in the second direction Y. The intermediate connection line 2223 is connected between the first connection line 2221 and the second connection line 2222.

[0194] Compared to the relatively regular rectangle of the connection structure 222, this configuration allows the sub-gate 221b located on one side of the break 221a to be connected by the first connection line 2221, and the sub-gate 221b located on the other side of the break 221a to be connected by the second connection line 2222. The sub-gate 221 with the break 221a can form a continuous sub-gate 221, thereby achieving the current transmission function while reducing the amount of paste used, reducing the wet weight of the printing paste, and reducing the manufacturing cost of the solar cell 20.

[0195] It should be noted that the first connecting line 2221 and the second connecting line 2222 can extend along the first direction X. The shapes of the first connecting line 2221, the second connecting line 2222, and the intermediate connecting line 2223 can be different. The width of the intermediate connecting line 2223 in the first direction X can be smaller than the width of the first connecting line 2221 and the second connecting line 2222 in the first direction X. Alternatively, the width of the intermediate connecting line 2223 in the first direction X can gradually change from the first connecting line 2221 towards the second connecting line 2222, making the connecting structure 222 a non-rectangular, non-trapezoidal shape with a large area. This avoids forming a connecting structure 222 on the solar cell semi-finished product 21 that consumes too much paste, increases the shading area, and affects the shading efficiency of the solar cell 20.

[0196] In some possible implementations, the width of the sub-gate 221 in the first direction X is W1, and the shortest length of the first connecting line 2221 and the second connecting line 2222 in the first direction X is W2, where W2 ≥ W1. By limiting the length of the first connecting line 2221 and the second connecting line 2222 in the first direction X to be greater than the width of the sub-gate 221 line in the first direction X, that is, a sufficiently large connection area can be provided to stably connect with the sub-gate 221b. During the formation of the connection structure 222, the connection offset of the first connecting line 2221 and the second connecting line 2222 can be controlled, improving the finished product defects caused by the offset.

[0197] In some embodiments, the length W3 of the connecting structure 222 in the second direction Y is 0.05mm to 1.6mm. Optionally, W3 can be 0.05mm to 1.3mm, 0.05mm to 1.0mm, or 0.05mm to 0.8mm, for example, 0.2mm, 0.6mm, or 1.0mm. Since the connecting structure 222 needs to be located at the break 221a and can connect between the grid lines located on both sides of the break 221a, by limiting the overall length of the connecting structure 222, the connecting structure 222 has an offset allowance in the second direction Y, reducing printing difficulty and thus reducing printing defects caused by grid breakage due to offset.

[0198] In some embodiments, the shortest length W2 of the first connecting line 2221 and the second connecting line 2222 in the first direction X is 40μm to 120μm. Optionally, W2 can be 40μm to 100μm, 40μm to 80μm, or 40μm to 60μm, for example, 50μm, 70μm, or 100μm. By limiting the range of W2, a certain offset can be reserved in the first direction X when connecting with the sub-gate 221b, thereby reducing the printing difficulty.

[0199] It should be noted that the shortest length W2 of the first connecting line 2221 and the second connecting line 2222 in the first direction X means that: the lengths of the first connecting line 2221 and the second connecting line 2222 in the first direction X can be equal, or the length of the first connecting line 2221 in the first direction X is greater than the length of the second connecting line 2222 in the first direction X, or the length of the first connecting line 2221 in the first direction X is less than the length of the second connecting line 2222 in the first direction X.

[0200] In some embodiments, the width W4 of the first connecting line 2221 and the second connecting line 2222 in the second direction Y is 2μm to 60μm. Optionally, W4 can be 2μm to 40μm, 2μm to 30μm, or 2μm to 20μm, for example, it can be 4μm, 10μm, or 20μm. By limiting the range of W4, when connecting with the sub-gate 221b, the amount of paste used can be reduced while still allowing the connecting structure 222 to be connected to the sub-gate 221b.

[0201] In some embodiments, the width W5 of the intermediate connecting line 2223 in the first direction X is 2μm to 60μm. Optionally, W5 can be 2μm to 40μm, 2μm to 30μm, or 2μm to 20μm, for example, 4μm, 10μm, or 20μm. By limiting the range of W5, while ensuring that the intermediate line is effectively connected between the first connecting line 2221 and the second connecting line 2222, the amount of slurry used can be reduced, the wet weight can be reduced, and the light-blocking area can be reduced.

[0202] In some embodiments, the shape of the connection structure 222 includes at least one of H-shape, N-shape, or inverted figure-eight shape. By employing a connection structure 222 with these shapes, effective connection between the connection structure 222 and the sub-grids 221b located on both sides of the break 221a can be ensured while reducing slurry loss.

[0203] It is understood that the shape of the connecting structure 222 is roughly the same as the shape of the connecting printing area 121 on the second screen 12, but the specific dimensions are different. The specific structure can be referred to the shape of the connecting printing area 121.

[0204] In one example, the width of the intermediate connecting line 2223 in the first direction X can be less than the shortest length of the first connecting line 2221 and the second connecting line 2222 in the first direction X, making the intermediate connecting line 2223 rectangular. The first connecting line 2221 and the second connecting line 2222 can have the same shape and size, both being rectangular, thus making the overall shape of the connecting structure 222 H-shaped. This configuration ensures that when the first connecting line 2221 and the second connecting line 2222 formed on the solar cell semi-finished product 21 are connected to the sub-grid 221, even with offset errors, the connection between the sub-grid 221b and the connecting line can be guaranteed. This allows the connecting structure 222 to effectively connect the sub-grids 221b located on both sides of the break 221a, and reduces paste loss, which is beneficial for cost reduction.

[0205] In another example, the width of the intermediate connecting line 2223 in the first direction X can be less than the shortest length of the first connecting line 2221 and the second connecting line 2222 in the first direction X, making the intermediate connecting line 2223 rectangular. Both the first connecting line 2221 and the second connecting line 2222 are rectangular, and their lengths in the first direction X can be unequal, allowing the overall shape of the connecting structure 222 to be an inverted I-shape. This configuration also ensures effective connection between the connecting structure 222 and the sub-grid 221 and reduces slurry loss, thereby helping to reduce costs.

[0206] In another example, the width of the intermediate connecting line 2223 in the first direction X can also be less than the shortest length of the first connecting line 2221 and the second connecting line 2222 in the first direction X. However, the intermediate connecting line 2223 is connected between the first connecting structure 222 and the second connecting structure 222 in an inclined manner, so that the intermediate connecting structure 222 presents a parallelogram. The first connecting line 2221 and the second connecting line 2222 can have the same shape and size, so that the overall shape of the connecting structure 222 is N-shaped. This also enables the connecting structure 222 formed by the connecting structure 222 to be effectively connected between the sub-grids 221 located on both sides of the break 221a, and can reduce the loss of slurry.

[0207] Of course, in other embodiments, the width of the intermediate connecting line 2223 in the first direction X is gradually changing from the first connecting line 2221 to the second connecting line 2222, for example, it first becomes smaller and then larger, and the overall shape of the connecting structure 222 is an inverted figure 8.

[0208] Preferably, the connection structure 222 is H-shaped, which is more conducive to ensuring the connection between the formed connection structure 222 and the sub-grid 221, reducing paste loss, reducing the shading area, and thus improving the conversion efficiency of the solar cell 20.

[0209] In this application embodiment, the solar cell can be 0BB (OBusbar, no main busbar), MBB (Multi Busbar, multiple main busbars 223), or SMBB (Super Multi Busbar). 0BB technology eliminates the main busbar 223 and uses solder ribbons to directly connect the sub-busbars 221 to collect and conduct current. This significantly reduces the metal shading area on the surface of the solar cell semi-finished product 21, increases the light-receiving area, and thus improves the power generation efficiency of the solar cell 20. MBB and SMBB technologies primarily collect the current from the sub-busbars 221 through the main busbar 223 and conduct the current through solder ribbons.

[0210] Taking the solar cell 20 in this application as an example, which is either MBB or SMBB.

[0211] In some embodiments, the electrode structure 22 further includes a main grid 223 extending along a first direction X. By setting the main grid 223 on the solar cell semi-finished product 21, the current formed by the collection of charge carriers by the secondary grid 221 is converged onto the main grid 223, and the current is discharged by welding the main grid 223 to the solder strip, effectively ensuring the welding area between the solder strip and the main grid 223.

[0212] That is, the electrode structure 22 may include a main gate 223 and a sub-gate 221. The main gate 223 extends along the first direction X, while the sub-gate 221 extends along the second direction Y. The main gate 223 and the sub-gate 221 intersect, so that the sub-gate 221 can concentrate the current onto the main gate 223.

[0213] Optionally, if a break 221a is formed on the sub-gate 221, the main gate 223 is spaced apart from the break 221a in the second direction Y, and / or the break 221a is located on the main gate 223.

[0214] Understandably, in one example, the main gate 223 is spaced apart from the break 221a in the second direction Y. Since the connecting structure 222 is located at the break 221a of the secondary gate 221, this arrangement allows the connecting structure 222 at the break 221a to be spaced apart from the main gate 223. In this way, the break 221a and the main gate 223 do not affect each other. By placing the connecting structure 222 at the break 221a and connecting it between the secondary gates 221 located on both sides of the break 221a, current can be transmitted through the secondary gates 221, thus allowing the current to converge normally onto the main gate 223.

[0215] In another example, referring to Figure 16, the break 221a is located on the main grid 223, meaning the main grid 223 can pass through the break 221a. In this case, the main grid 223 is connected to the sub-grids 221b on both sides through the connecting structure 222. This method utilizes the connecting structure 222 at the break 221a to strengthen the connection between the main grid 223 and the sub-grids 221. However, it should be noted that this method places requirements on the dimensions of the connecting structure 222. Specifically, because the connecting structure 222 is printed simultaneously with the main grid 223 and uses the same printing paste as the main grid 223, the final connecting structure 222 has a low line height, making it highly susceptible to grid breakage during welding.

[0216] In another example, the main grid 223 is spaced apart from a portion of the break 221a in the second direction Y, while another portion of the break 221a is located on the main grid 223. It is understood that in this example, the connection structure 222 spaced apart from the main grid 223 can be the same as or different from the connection structure 222 located on the main grid 223. For example, the function of the connection structure 222 spaced apart from the main grid 223 is to connect the sub-grid 221 with the break 221a. As long as the connection is satisfied, the dimensions (width, length, height, etc.) of the corresponding connection structure 222 can be set smaller to reduce slurry loss. However, the connection structure 222 located on the main grid 223 needs to be larger to meet the requirements of connecting the disconnected sub-grid 221b while also satisfying the current convergence and welding requirements. This is to avoid grid breakage due to the reaction between the solder strip and the silver contained in the sub-grid 221 during welding.

[0217] For example, there are three main gates 223 and two columns of connecting structures 222, one column of which is located between two main gates 223 and the other column of connecting structures 222 is located on the last main gate 223.

[0218] It should be noted that the sub-grid 221 is mainly for collecting current. When the break 221a is spaced apart from the main grid 223, each main and sub-grid 221 becomes an independent region. Since the surface of the solar cell 20 needs to be energized during laser-induced sintering, and if there is a break 221a between the sub-grids 221, the entire cell cannot be energized, making the process impossible. Furthermore, the IV and EL testing machines used in production lines typically use probes, and the probe pressing position is mainly on the main grid 223, and not every main grid 223 has one. Therefore, current mass-produced IV and EL testing machines cannot be used, requiring modification of these devices. Therefore, by setting the main grid 223 on the electrode structure 22 to collect the current collected by the sub-grids 221, the connection structure 222 can improve the energizing situation of laser-induced sintering while also improving the current transmission method, achieving versatility without changing the current testing equipment.

[0219] In some embodiments, the main gate 223 includes multiple main gates 223, which are spaced apart along the second direction Y. When the main gates 223 are spaced apart from the break 221a along the second direction Y, the break 221a is located between two adjacent main gates 223. Since a reasonable increase in the number of main gates 223 can reduce the transmission distance of the sub-gates 221, this application shortens the distance between the sub-gates 221 between two connected main gates 223 by setting multiple main gates 223, thereby reducing the gate line transmission resistance and the series resistance, which is beneficial to improving the photoelectric conversion efficiency.

[0220] It should be noted that when the break 221a is located between two adjacent main gates 223, there can be multiple breaks 221a. That is, there are multiple breaks on the sub-gate 221 located between the two main gates 223, and the multiple breaks 221a can be set at intervals along the second direction Y.

[0221] In this embodiment, SMBB technology can be used, and the number of main grids 223 can be 16 to 26. For example, the number of main grid printed areas 122 can be 16, 18, 22, or 24, resulting in a larger number of main grids 223 with smaller spacing. Of course, in other embodiments, the number of main grids 223 can also be other numbers. This embodiment does not specifically limit the number of main grids 223, as long as it meets the requirements of the solar cell.

[0222] Since the overlap state at the junction of the main grid 223 and the sub-grid 221 directly affects the collection and extraction of photogenerated carriers, the short-circuit current of the solar cell 20 will decrease significantly when the overlap is poor due to a broken wire or grid. Therefore, an overlap structure is usually set at the junction of the main grid 223 and the sub-grid 221.

[0223] It is understandable that when the break 221a is located on the main gate 223, the connection structure 222 is equivalent to an overlapping structure. Based on the ability to connect the sub-gates 221b located on both sides of the break 221a, the main gate 223 and the sub-gate 221 are also overlapped to satisfy the collection and extraction of photogenerated carriers. However, since there is only one layer of connection structure 222 at the intersection of the main gate 223 and the sub-gate 221, and this connection structure 222 is formed simultaneously with the main gate 223, it may not meet the welding requirements. Therefore, in this embodiment, it is preferable to space the break 221a and the main gate 223, so that not only can the main gate overlapping structure 224 be formed simultaneously during the printing of the main gate 223, but also the sub-gate overlapping structure 225 can be formed simultaneously during the printing of the sub-gate 221, and the two can be overlapped.

[0224] In some embodiments, when the sub-gate 221 has the aforementioned break 221a, and the main gate 223 is spaced apart from the break 221a in the second direction Y, the electrode structure 22 further includes a main gate overlap structure 224. The main gate overlap structure 224 is connected to the main gate 223 and is located at the intersection of the main gate 223 and the sub-gate 221b. This configuration, by providing the main gate overlap structure 224 located at the intersection of the main gate 223 and the sub-gate 221b, strengthens the connection between the main gate 223 and the sub-gate 221b, further ensuring good contact between the main gate 223 and the sub-gate 221b while reducing metal recombination, effectively lowering metal resistance, improving current transmission, and thus improving battery efficiency. Simultaneously, it saves on paste usage and reduces costs.

[0225] Because a separate main gate overlap structure 224 is set up to connect the main gate 223 and the sub-gate 221b, the height of the main gate overlap structure 224 will be reduced. This will greatly increase the risk of gate breakage during subsequent welding.

[0226] Based on this, in some possible embodiments, referring to Figures 17 and 18, the electrode structure 22 further includes a sub-grid overlap structure 225, which is connected to the sub-grid 221b, and the sub-grid overlap structure 225 and the main grid overlap structure 224 are at least partially overlapped. By simultaneously setting the main grid overlap structure 224 and the sub-grid overlap structure 225 on the solar cell semi-finished product 21, and making them at least partially overlapped, the height of the overlap structure located at the intersection of the main grid 223 and the sub-grid 221b can be further increased. This can reduce the risk of grid breakage caused by the reduced height of the overlap structure at the intersection of the main grid 223 and the sub-grid 221 due to low wet weight, thereby improving the welding effect.

[0227] Optionally, the main grid overlap structure 224 covers the secondary grid overlap structure 225, that is, the projection of the secondary grid overlap structure 225 on the solar cell semi-finished product 21 falls within the projection range of the main grid overlap structure 224 on the solar cell semi-finished product 21. Alternatively, the secondary grid overlap structure 225 covers the main grid overlap structure 224, that is, the projection of the main grid overlap structure 224 on the solar cell semi-finished product 21 falls within the projection range of the secondary grid overlap structure 225 on the solar cell semi-finished product 21. By setting the main grid overlap structure 224 to cover the secondary grid overlap structure 225 or the secondary grid overlap structure 225 to cover the main grid overlap structure 224, on the one hand, the overlapping structure area can be larger, which means that a larger area has a higher height, thus making it more conducive to meeting welding requirements; on the other hand, since the paste will diffuse to a certain extent after printing, this form of covering is beneficial to the consistency of appearance.

[0228] When the main gate overlap structure 224 covers the secondary gate overlap structure 225, the maximum width L1 of the main gate overlap structure 224 in the first direction X is 35μm to 90μm. Optionally, L1 can be 35μm to 80μm, 35μm to 70μm, 35μm to 60μm, or 50μm to 90μm, for example, it can be 60μm, 70μm, or 80μm.

[0229] The minimum width L2 of the main gate overlap structure 224 in the first direction X is 20μm to 90μm. Optionally, L2 can be 20μm to 30μm, 20μm to 50μm, 20μm to 60μm or 20μm to 70μm, for example, it can be 30μm, 50μm or 80μm.

[0230] The length L3 of the main grid overlap structure 224 in the second direction Y is 0.65mm to 1.7mm. Optionally, L3 can be 0.65mm to 1.5mm, 0.65mm to 1.2mm, or 0.65mm to 1.0mm, for example, it can be 0.7mm, 1.0mm, or 1.3mm.

[0231] The maximum width L4 of the subgate overlap structure 225 in the first direction X is 20μm to 75μm. Optionally, L4 can be 20μm to 60μm, 20μm to 50μm, 20μm to 40μm, or 35μm to 75μm, for example, it can be 45μm, 55μm, or 65μm.

[0232] The minimum width L5 of the subgate overlap structure 225 in the first direction X is 15μm to 75μm. Optionally, L5 can be 5μm to 20μm, 15μm to 30μm, or 15μm to 50μm, for example, it can be 20μm, 30μm, or 50μm.

[0233] The length L6 of the sub-gate overlap structure 225 in the second direction Y is 0.55mm to 1.6mm. Optionally, L6 can be 0.55mm to 1.4mm, 0.55mm to 1.0mm, or 0.5mm to 0.8mm, for example, it can be 0.6mm, 0.8mm, or 1.2mm.

[0234] When the main gate overlap structure 224 covers the sub-gate overlap structure 225, by limiting the size of the main gate overlap printing area 123 and the sub-gate overlap printing area 112 to be within a reasonable range, it can prevent the printing grid from being broken due to the huge difference in width and height from the main gate 223 to the sub-gate 221 during printing, while ensuring sufficient area to meet the welding needs, and preventing the sub-gate 221 from being broken due to the melting of solder after welding.

[0235] It is understandable that the widths of the main gate overlap structure 224 and the sub-gate overlap structure 225 are gradually varied along the second direction Y. Controlling the minimum width ensures a stable connection between the sub-gate 221b and the main gate 223, preventing breakage. Controlling the maximum width allows for a larger area to collect current, maximizing the conduction current and reducing conduction resistance, thus facilitating effective contact and stable current transmission. Simultaneously, setting the size of the printing area of ​​the main gate overlap structure 224 to be compatible with the size of the sub-gate overlap printing area 112 allows for a certain offset allowance when the sub-gate overlap structure 225 falls within the range of the main gate overlap structure 224, avoiding a poor overall appearance of the overlap structure.

[0236] When the subgate overlap structure 225 covers the main gate overlap structure 224, the maximum width L1 of the main gate overlap structure 224 in the first direction X is 20μm to 75μm. Optionally, L1 can be 20μm to 60μm, 20μm to 50μm, 20μm to 40μm, or 35μm to 75μm, for example, it can be 45μm, 55μm, or 65μm.

[0237] The minimum width L2 of the main gate overlap structure 224 in the first direction X is 15μm to 75μm. Optionally, L2 can be 5μm to 20μm, 15μm to 30μm, or 15μm to 50μm, for example, it can be 16μm, 17μm, or 18μm.

[0238] The length L3 of the main grid overlap structure 224 in the second direction Y is 0.55mm to 1.6mm. Optionally, L3 can be 0.55mm to 1.4mm, 0.55mm to 1.0mm, or 0.5mm to 0.8mm, for example, it can be 0.6mm, 0.8mm, or 1.2mm.

[0239] The maximum width L4 of the subgate overlap structure 225 in the first direction X is 35μm to 90μm. Optionally, L4 can be 35μm to 80μm, 35μm to 70μm, 35μm to 60μm or 50μm to 90μm, for example, it can be 60μm, 70μm or 80μm, etc.

[0240] The minimum width L5 of the subgate overlap structure 225 in the first direction X is 20μm to 90μm. Optionally, L5 can be 20μm to 30μm, 20μm to 50μm, 20μm to 60μm or 20μm to 70μm, for example, it can be 30μm, 50μm or 80μm.

[0241] The length L6 of the sub-gate overlap structure 225 in the second direction Y is 0.65mm to 1.7mm. Optionally, L6 can be 0.65mm to 1.5mm, 0.65mm to 1.2mm, or 0.65mm to 1.0mm, for example, it can be 0.7mm, 1.0mm, or 1.3mm.

[0242] When the sub-gate overlap structure 225 covers the main gate overlap structure 224, by limiting the size of the sub-gate overlap printing area 112 and the main gate overlap printing area 123 to be within a reasonable range, it can prevent the printing grid from being broken due to the huge difference in width and height from the main gate 223 to the sub-gate 221 during printing, while ensuring sufficient area to meet the welding needs, and preventing the sub-gate 221 from being broken due to the melting of solder after welding.

[0243] In other embodiments, when the sub-gate 221 does not have a break 221a and the battery structure does not have a connection structure 222, the connection between the main gate 223 and the sub-gate 221 can also be provided with the above-mentioned main gate overlap structure 224 and sub-gate overlap structure 225. The design of the main gate overlap structure 224 and the sub-gate overlap structure 225 can be referred to the above description, and will not be repeated here.

[0244] In some embodiments, referring to Figures 12 and 13, the electrode structure 22 further includes pads 226 and harpoons 227. The pads 226 include first pads 226a and second pads 226b. The first pads 226a are provided at both ends of the main gate 223, and the second pads 226b are provided on the main gate 223 and located between the two first pads 226a. The harpoons 227 are located at both ends of each main gate 223 and connected to the first pads 226a. The area of ​​the first pads 226a is larger than the area of ​​the second pads 226b, so that the first pads 226a are more conducive to the connection with the harpoons 227.

[0245] Optionally, the first pad 226a and the second pad 226b can be strip structures that extend along the second direction Y. Of course, the first pad 226a and the second pad 226b can also be inclined. This application embodiment does not impose specific limitations on this.

[0246] It should be noted that the harpoon 227 in this embodiment can be printed simultaneously with the main grid 223. By placing the harpoon 227 on the main grid 223, the silver paste used in the main grid 223 typically has a lower solid content, thereby reducing burn-through silver paste loss. Moreover, since the conductive paste solid content of the main grid 223 is lower than that of the conductive paste of the sub-grid 221, due to the influence of the paste solid content and its organic carrier expansion, the actual height after sintering is lower when the ink application amount is consistent. Therefore, in the electrode printing structure of this application, placing the harpoon 227 structure 14 on the main grid 223 can also reduce the height of the harpoon 227, thereby reducing passivation damage, increasing the open-circuit voltage, and thus improving the photoelectric conversion efficiency.

[0247] The following will compare and explain the method of forming the sub-gate printing area 111 on the substrate 110 and the method of forming the sub-gate printing area 111 using a wire mesh.

[0248] Referring to Figures 19 to 22, Figure 19(a), (b), and (c) correspond to the three-dimensional topography, cutting center line, and height profile curve of the sub-grid 221 formed by setting the sub-grid printing area 111 on the wire mesh at cutting position 1, respectively. Figure 20(a), (b), and (c) correspond to the three-dimensional topography, cutting center line, and height profile curve of the sub-grid 221 formed by setting the sub-grid printing area 111 on the wire mesh at cutting position 2, respectively. Figure 21(a), (b), and (c) correspond to the three-dimensional topography, cutting center line, and height profile curve of the sub-grid 221 formed by setting the sub-grid printing area 111 on the first screen 11 of this application at cutting position 1, respectively. Figure 22(a), (b), and (c) correspond to the three-dimensional topography, cutting center line, and height profile curve of the sub-grid 221 formed by setting the sub-grid printing area 111 on the first screen 11 of this application at cutting position 2, respectively.

[0249] Among them, the height profile curve shown in Figure 19 to Figure 22(c) is a profile curve obtained by taking the center line on the width of the sub-gate as the selection line and referring to the surface of the solar cell as the reference. The upper and lower straight lines shown in Figure 19 to Figure 21(b) represent the width profile of the sub-gate, and the straight line with the arrow is the selection line.

[0250] As can be seen from the figure, when printing the sub-grid 221 using a wire mesh screen, the paste exhibits severe concavity, causing the waveform of the height profile curve of the sub-grid 221 to dip at the corresponding positions, resulting in large fluctuations. In contrast, the sub-grid 221 formed using the sub-grid printing area 111 on the first screen 11 of this application has a smoother height profile curve. The sub-grid 221 exhibits a flatter shape in the height direction and a better narrowing effect in the width direction, resulting in superior overall smoothness.

[0251] Referring to Table 1, Table 1 shows the detection of any two positions (as shown in Figures 19 to 22 of the sub-grid 221) of the formed sub-grid 221 when printing with a wire mesh and the first screen of this application, respectively. The smoothing factor is compared by selecting the center line through the width of the sub-grid 221 as the selection line (see (b) in Figures 19 to 22, where the upper and lower straight lines represent the width outline of the sub-grid, and the straight line with the arrow is the selection line) and calculating the height value of the sub-grid 221 with the surface of the solar cell as the reference.

[0252] Specifically, referring to Figures 19 to 22, the height profile of the sub-grating 221 is measured using a 3D microscope at 50x magnification. Based on the height curve obtained from the height profile, height values ​​are derived from the height curve. For example, this application derives 1024 height point values, and calculates the variance of these 1024 height point values ​​using the mathematical statistical concept. This variance is used to characterize the fluctuation of the height of the sub-grating 221, which is the smoothing factor described in this application. It should be noted that, depending on the system settings of different 3D microscope models, any number of height point values ​​can be derived. To reduce the impact of outlier data points on the error calculation of the smoothing factor, this application needs to remove outlier height point values. Outlier data points are defined as height data point values ​​that exceed 30% of the average height point values. For example, assuming the average of the 1024 height point values ​​is X... ave The outlier data point is X. i When |X i -X ave | / X ave The height data point value when it is >30% belongs to the abnormal height data point value described in this application.

[0253] When using a wire mesh screen, the smoothing factors obtained at two different locations were 5.12 and 6.82, respectively. However, when using the first screen printing plate of this application, the smoothing factors obtained at the same two locations were 0.23 and 0.12, respectively. It is evident that the smoothing factor of the sub-grid formed using the first screen printing plate is smaller. Furthermore, referring to Figures 19 to 22, it can be seen that compared to the uneven sub-grid produced by wire mesh screen printing, the sub-grid obtained by the first screen printing plate of this application is smoother and has a more even overall outline.

[0254] Table 1

[0255] Please refer to Figures 23 and 24. In Figure 23, (a), (b), and (c) are cross-sectional profile views of the sub-grid 221 formed using a wire mesh at different positions. In Figure 24, (a), (b), and (c) are cross-sectional profile views of the sub-grid 221 formed using the first screen 11 of this application at different positions. Figures 23 and 24 are cross-sectional profile views of the sub-grid 221 printed using the wire mesh and the first screen 11 with a width of 8 μm for the sub-grid printing holes 111a.

[0256] See Table 2, which shows comparative data on the width and height of cross sections taken at any three positions of the printed subgrid 221 when printing with a wire mesh and a first screen printing plate.

[0257] It is evident that, considering uncontrollable factors such as process fluctuations and ink flowability in actual printing, the actual width of the sub-grid formed by wire mesh printing is wider. In contrast, the actual width of the sub-grid formed by the first screen printing is smaller than that of the sub-grid 221 obtained by wire mesh printing, resulting in a narrower line width for the sub-grid 221. Referring to Figures 19 to 22, it can be seen that when using wire mesh printing, the ink penetration is affected at the locations where the wire is blocked, leading to uneven ink penetration at those locations. This results in a depression on the sub-grid 221 corresponding to the blocked area, while other areas protrude, creating an uneven surface and causing greater fluctuations in the actual printed width. However, the method of printing the sub-grid 221 using the first screen 11 of this application not only results in a flatter printing of the sub-grid but also reduces the difference between the designed and actual shape of the sub-grid 221, making the printing process more controllable and more conducive to narrowing the line width.

[0258] Table 2

[0259] Fourthly, embodiments of this application also include a photovoltaic module (not shown), which may include the solar cell 20 described in the third aspect above. Of course, it may also include a frame, photovoltaic glass, encapsulation materials, etc., together constituting a photovoltaic module suitable for various outdoor environments, such as rooftops and building surfaces, and widely used in solar photovoltaic systems.

[0260] Fifthly, embodiments of this application also disclose a method for printing a solar cell 20 using the screen printing structure 10 as described above, the method comprising:

[0261] Using the first screen 11, a sub-grid 221 with a break 221a is printed on the solar cell semi-finished product 21;

[0262] Multiple connection structures 222 are printed on the solar cell semi-finished product 21 using a second screen 12, so that the connection structures 222 connect the sub-grids 221 located on both sides of the break 221a.

[0263] Optionally, firstly, a second screen 12 can be used to print multiple connection structures 222 on the solar cell semi-finished product 21; secondly, the first screen 11 is used to print sub-grids 221 with breaks 221a on the solar cell semi-finished product 21, so that the connection structures 222 are located at the breaks 221a and connected between the sub-grids 221 located on both sides of the breaks 221a.

[0264] In this embodiment, the printing path for the electrode structure 22 can be as follows: first, print the main grid 223 on the back of the solar cell semi-finished product 21, then print the sub-grid 221 on the back, then print the main grid 223 on the front, and finally print the sub-grid 221 on the front. It is understood that the sub-grid 221 is thinner, and if it is printed first, it is easy to scratch the sub-grid 221 when printing the main grid 223, which will affect the current transmission.

[0265] It should be noted that the method of printing solar cells using the screen structure described above in the embodiments of this application is suitable for application in the field of solar cells. It can be applied to the preparation of various solar cells such as bifacial cells, such as heterojunction cells, passivated contact solar cells, etc.

[0266] The foregoing has provided a detailed description of the screen printing structure, solar cell, photovoltaic module, and method for printing solar cells disclosed in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the screen printing structure, solar cell, photovoltaic module, and method for printing solar cells of this application and their core ideas. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A screen printing structure, characterized in that, Applied to solar cells, the solar cells include semi-finished solar cells, and the screen structure includes: The first screen printing plate includes a substrate, the substrate having multiple sub-gate printing areas, the multiple sub-gate printing areas being spaced apart along a first direction, each sub-gate printing area including multiple sub-gate printing holes, the multiple sub-gate printing holes being spaced apart in a second direction, the multiple sub-gate printing holes of each sub-gate printing area being configured to form a sub-gate with a break on the solar cell semi-finished product. The second screen has a connecting printing area, which is configured to form a connecting structure on the solar cell semi-finished product located at the break, and the connecting structure is configured to connect the sub-grids located on both sides of the break in the second direction. The first direction and the second direction intersect.

2. The screen printing structure according to claim 1, characterized in that, The width D1 of the sub-gate printed hole in the first direction is 2μm to 30μm.

3. The screen printing structure according to claim 1 or 2, characterized in that, In the second direction, a gap region is formed between two adjacent sub-gate printing holes, the length of the sub-gate printing hole in the second direction is D2, the width of the gap region in the second direction is D3, and D2 / D3 is 35~240.

4. The screen printing structure according to claim 3, characterized in that, The length D2 of the sub-gate printing hole in the second direction is 5mm to 30mm, and the width D3 of the interval area in the second direction is 0.05mm to 1.5mm.

5. The screen printing structure according to any one of claims 1 to 4, characterized in that, The connection printing area includes a first connection printing hole, a second connection printing hole, and an intermediate connection printing hole. The intermediate connection printing hole connects the first connection printing hole and the second connection printing hole. The first connection printing hole is configured to form a first connection line on the solar cell semi-finished product, and the first connection line is connected to the sub-gate located on one side of the break in the second direction. The second connection printing hole is configured to form a second connection line on the solar cell semi-finished product, and the second connection line is connected to the sub-gate located on the other side of the break in the second direction. The intermediate connection printing hole is configured to form an intermediate connection line on the solar cell semi-finished product, and the intermediate connection line is connected between the first connection line and the second connection line.

6. The screen printing structure according to claim 5, characterized in that, The width of the sub-gate printing hole in the first direction is D1, and the shortest length of the first connecting printing hole and the second connecting printing hole in the first direction is D4, where D4 ≥ D1.

7. The screen printing structure according to claim 6, characterized in that, The length D5 of the connecting printing area in the second direction is 0.05mm to 1.5mm.

8. The screen printing structure according to claim 7, characterized in that, The shortest length D4 of the first connecting printed hole and the second connecting printed hole in the first direction is 20μm to 200μm, and / or the width D6 of the first connecting printed hole and the second connecting printed hole in the second direction is 10μm to 200μm, and / or the width D7 of the intermediate connecting printed hole in the first direction is 10μm to 200μm.

9. The screen printing structure according to any one of claims 1 to 8, characterized in that, The second screen does not have a main grid printing area. In the second direction, a gap area is formed between two adjacent sub-grid printing holes. The length of the sub-grid printing hole in the second direction is D2, the width of the gap area in the second direction is D3, and the number of gap areas is M. The aperture ratio of the first screen is F, F = D2(M+1) / [D2(M+1)+D3*M], 90% ≤ F < 100%.

10. The screen printing structure according to any one of claims 1 to 8, characterized in that, The second screen printing plate also has a main grid printing area, which is configured to form a main grid on the solar cell semi-finished product; The main grid printing area is spaced apart from the connecting printing area in the second direction, and / or the connecting printing area is at least partially connected to the main grid printing area.

11. The screen printing structure according to claim 10, characterized in that, The number of main grid printing areas is N. In the second direction, a gap area is formed between two adjacent sub-grid printing holes. The number M of the gap area of ​​each sub-grid printing area is: 1 / 10N≤M≤20N; where N is an integer and N≥1, and M is an integer.

12. The screen printing structure according to claim 10 or 11, characterized in that, The main grid printing area includes multiple main grid printing areas, which are spaced apart along the second direction. When the main grid printing areas are spaced apart from the connecting printing areas in the second direction, the connecting printing areas are located between two adjacent main grid printing areas.

13. The screen printing structure according to any one of claims 10 to 12, characterized in that, When the main grid printing area is spaced apart from the connecting printing area in the second direction, the second screen also has a main grid overlapping printing area. The main grid overlapping printing area is at least partially located on the main grid printing area and is connected to the main grid printing area. The main grid overlapping printing area is configured to form a main grid overlapping structure at the intersection of the main grid and the sub-grid on the solar cell semi-finished product.

14. The screen printing structure according to claim 13, characterized in that, The substrate also has a sub-gate overlap printing area, which is at least partially located on the sub-gate printing area and communicates with the sub-gate printing hole. The sub-gate overlap printing area is configured to form a sub-gate overlap structure on the solar cell semi-finished product, and the sub-gate overlap structure is at least partially overlapped with the main gate overlap structure.

15. The screen printing structure according to claim 14, characterized in that, When the main gate overlapping structure covers the secondary gate overlapping structure, the maximum width T1 of the main gate overlapping printing area in the first direction is 30μm to 80μm, the minimum width T2 of the main gate overlapping printing area in the first direction is 13μm to 80μm, the length T3 of the main gate overlapping printing area in the second direction is 0.6mm to 1.6mm, the maximum width T4 of the secondary gate overlapping printing area in the first direction is 15μm to 70μm, the minimum width T5 of the secondary gate overlapping printing area in the first direction is 10μm to 70μm, and the length T6 of the secondary gate overlapping printing area in the second direction is 0.5mm to 1.5mm; or, When the sub-gate overlapping structure covers the main gate overlapping structure, the maximum width T1 of the main gate overlapping printing area in the first direction is 15μm to 70μm, the minimum width T2 of the main gate overlapping printing area in the first direction is 10μm to 70μm, the length T3 of the main gate overlapping printing area in the second direction is 0.5mm to 1.5mm, the maximum width T4 of the sub-gate overlapping printing area in the first direction is 30μm to 80μm, the minimum width T5 of the sub-gate overlapping printing area in the first direction is 13μm to 80μm, and the length T6 of the sub-gate overlapping printing area in the second direction is 0.6mm to 1.6mm.

16. A solar cell, characterized in that, include: Semi-finished solar cells; An electrode structure includes multiple sub-gates and a connecting structure. The multiple sub-gates are spaced apart along a first direction. Each sub-gate includes multiple sub-sub-gates. The multiple sub-sub-gates are spaced apart in a second direction to form a break between two adjacent sub-sub-gates. The connecting structure is located at the break and is connected between two adjacent sub-sub-gates in the second direction. The first direction and the second direction intersect.

17. The solar cell according to claim 16, characterized in that, The width W1 of the sub-gate in the first direction is 4μm to 30μm.

18. The solar cell according to claim 16 or 17, characterized in that, The height H of the cross-section of the sub-gate is 1 μm to 10 μm, and / or the smoothing factor of the sub-gate in the height direction is less than or equal to 1.

19. The solar cell according to any one of claims 16 to 18, characterized in that, The connection structure includes a first connecting line, a second connecting line, and an intermediate connecting line. The first connecting line is connected to one of the sub-gates located on one side of the break in the second direction. The second connecting line is connected to another sub-gate located on the other side of the break in the second direction. The intermediate connecting line is connected between the first connecting line and the second connecting line.

20. The solar cell according to claim 19, characterized in that, The width of the sub-gate in the first direction is W1, and the shortest length of the first connecting line and the second connecting line in the first direction is W2, where W2 ≥ W1.

21. The solar cell according to claim 20, characterized in that, The length W3 of the connecting structure in the second direction is 0.05mm to 1.6mm.

22. The solar cell according to claim 21, characterized in that, The shortest length W2 of the first connecting line and the second connecting line in the first direction is 40μm to 120μm, and / or the width W4 of the first connecting line and the second connecting line in the second direction is 2μm to 60μm, and / or the width W5 of the intermediate connecting line in the first direction is 2μm to 60μm.

23. The solar cell according to any one of claims 16 to 22, characterized in that, The electrode structure further includes a main grid, which is spaced apart from the break in the second direction, and / or the break is located on the main grid.

24. The solar cell according to claim 23, characterized in that, When the main grid is spaced apart from the break in the second direction, the electrode structure further includes a main grid overlap structure, which is connected to the main grid and located at the intersection of the main grid and the sub-grid.

25. The solar cell according to claim 24, characterized in that, The electrode structure further includes a sub-gate overlap structure, which is connected to the sub-gate, and the sub-gate overlap structure and the main gate overlap structure are at least partially overlapped.

26. The solar cell according to claim 25, characterized in that, When the main gate overlap structure covers the secondary gate overlap structure, the maximum width L1 of the main gate overlap structure in the first direction is 35μm to 90μm, the minimum width L2 of the main gate overlap structure in the first direction is 20μm to 90μm, the length L3 of the main gate overlap structure in the second direction is 0.65mm to 1.7mm, the maximum width L4 of the secondary gate overlap structure in the first direction is 20μm to 75μm, the minimum width L5 of the secondary gate overlap structure in the first direction is 15μm to 75μm, and the length L6 of the secondary gate overlap structure in the second direction is 0.55mm to 1.6mm. or, When the sub-gate overlapping structure covers the main gate overlapping structure, the maximum width L1 of the main gate overlapping structure in the first direction is 20μm to 75μm, the minimum width L2 of the main gate overlapping structure in the first direction is 15μm to 75μm, the length L3 of the main gate overlapping structure in the second direction is 0.55mm to 1.6mm, the maximum width L4 of the sub-gate overlapping structure in the first direction is 35μm to 90μm, the minimum width L5 of the sub-gate overlapping structure in the first direction is 20μm to 90μm, and the length L6 of the sub-gate overlapping structure in the second direction is 0.65mm to 1.7mm.

27. The solar cell according to any one of claims 23 to 26, characterized in that, The electrode structure further includes pads and a fork. The pads include a first pad and a second pad. The first pads are provided at both ends of the main gate. The second pad is provided on the main gate and located between the two first pads. The fork is located at both ends of the main gate and connected to the first pads. The area of ​​the first pad is larger than the area of ​​the second pad.

28. A photovoltaic module, characterized in that, Includes the solar cell as described in any one of claims 16 to 27.

29. A method for printing solar cells using a screen printing structure as described in any one of claims 1 to 15, characterized in that, The method includes: The sub-grid with the fracture is printed on the solar cell semi-finished product using the first screen printing plate; Multiple connection structures are printed on the solar cell semi-finished product using the second screen printing plate, so that the connection structures are connected between the sub-grids located on both sides of the break.

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