Screen printing plate and manufacturing method thereof, solar cell and production method thereof, and photovoltaic module

Abstract

The invention relates to the technical field of printing screens, in particular to a screen and a manufacturing method thereof, a solar cell and a production method thereof, and a photovoltaic module. The screen printing plate comprises a film body, graphical grid line printing holes are formed in the film body, the grid line printing holes comprise grid line main body printing holes and lap joint printing holes which are communicated, and the grid line main body printing holes are configured to be consistent with an auxiliary grid printing area or a main grid printing area in graph. The lap joint printing hole is configured to be consistent with the pattern of the lap joint printing area; in the thickness direction of the film body, one end of each grid line main body printing hole is exposed out of the first surface, and the other end of each grid line main body printing hole is positioned in the film body; the lap joint printing hole penetrates through the film body, and the two ends of the lap joint printing hole are exposed out of the first face and the second face respectively. When the screen printing plate is used for printing, not only can the slurry cost be reduced, but also higher printing quality can be achieved.

Description

Technical Field

[0001] This application relates to the field of printing screen technology, and in particular to a screen and its manufacturing method, a solar cell and its production method, and a photovoltaic module. Background Technology

[0002] Low-solids paste reduces the production cost of solar cells by decreasing metal consumption. However, when printing grid lines using a low-solids paste through a printing screen, the lower metal content results in poor grid line morphology, which can easily lead to solder joint breakage during module welding. This makes it difficult to balance low cost and high printing quality in the solar cell production process. Summary of the Invention

[0003] This application discloses a screen printing plate and its manufacturing method, a solar cell and its production method, and a photovoltaic module, which can reduce the cost of printing paste while achieving high printing quality.

[0004] To achieve the above objectives, in a first aspect, embodiments of this application disclose a screen printing plate configured to print on the printing surface of a solar cell. The printing surface has a sub-grid printing area, a main grid printing area, and an overlap printing area, wherein the overlap printing area is located at the intersection of the sub-grid printing area and the main grid printing area.

[0005] The screen printing plate includes a film body, and in the thickness direction of the film body, the film body has a first side and a second side disposed opposite to each other, wherein the first side is configured to be opposite to the surface to be printed when the screen printing plate is being printed.

[0006] The film body is provided with patterned grid line printing holes, the grid line printing holes include interconnected grid line main printing holes and overlapping printing holes, the grid line main printing holes are configured to be consistent with the pattern of the sub-grid printing area or the main grid printing area, and the overlapping printing holes are configured to be consistent with the pattern of the overlapping printing area.

[0007] In the thickness direction of the film body, one end of the main printing hole of the grid line is exposed on the first surface, and the other end of the main printing hole of the grid line is located inside the film body; the printing hole at the overlap penetrates the film body, and the two ends of the printing hole at the overlap are exposed on the first surface and the second surface, respectively.

[0008] In one possible implementation of the first aspect, the thin film body includes:

[0009] A first film layer, configured to face the surface to be printed during printing on the screen; the main printing holes of the grid lines are disposed on the first film layer and penetrate the thickness direction of the first film layer; the first film layer is also provided with a first printing through-hole penetrating the thickness direction of the first film layer, the first printing through-hole being configured to correspond to the pattern of the printing area at the overlap; and

[0010] A second film layer is stacked on the first film layer. The second film layer has a second printed through-hole that extends through the thickness direction of the second film layer. The second printed through-hole is configured to match the pattern of the printing area at the overlap. The second printed through-hole is stacked on the first printed through-hole and combined with the first printed through-hole to form the printing hole at the overlap.

[0011] In one possible implementation of the first aspect, the first film layer is a first PI film;

[0012] And / or, the second film layer is a second PI film;

[0013] And / or, the thickness of the first film layer is 2 μm to 4 μm;

[0014] And / or, the thickness of the second film layer is 1 μm to 3 μm.

[0015] In a possible implementation of the first aspect, the main printing hole of the gate line is configured to correspond to the pattern of the sub-gate printing area, and the width of the widest part of the overlapping printing hole is greater than the width of the main printing hole of the gate line.

[0016] And / or, along the length direction of the printed hole at the overlap, the width of the printed hole at the overlap decreases from the middle to both ends.

[0017] In one possible implementation of the first aspect, the width of the widest point of the printed hole at the overlap is 40μm to 53μm; the width of the printed hole in the main body of the grid line is 15μm to 17μm.

[0018] Secondly, embodiments of this application disclose a method for manufacturing a screen printing plate as described in the first aspect, comprising the following steps:

[0019] Patterned grid lines are printed by oriented openings on the thin film body.

[0020] In a possible implementation of the second aspect, the step of orientedly opening holes in the thin film body to obtain patterned grid line printed holes includes:

[0021] Laser-guided drilling is performed on the first film layer to obtain the main printed hole of the grid line and the first printed through hole; wherein, the main printed hole of the grid line and the first printed through hole both penetrate the thickness direction of the first film layer, and the pattern of the first printed through hole is consistent with the pattern of the printing area at the overlap.

[0022] A second film layer is superimposed on the first film layer; wherein the second film layer and the first film layer are adsorbed and bonded in a vacuum environment, and the edges of the second film layer and the edges of the first film layer are bonded together with an adhesive;

[0023] A second printed through-hole is obtained by laser-directed drilling on the second film layer; wherein the second printed through-hole penetrates the thickness direction of the second film layer, and the pattern of the second printed through-hole is consistent with that of the printing area at the overlap, and the second printed through-hole and the first printed through-hole are stacked to form the printing hole at the overlap.

[0024] Thirdly, embodiments of this application disclose a method for producing a solar cell, which uses a screen as described in the first aspect to produce the solar cell, or uses a screen obtained by the manufacturing method as described in the second aspect to produce the solar cell.

[0025] The method for producing the solar cell includes the following steps:

[0026] The screen is placed on the printing surface of the solar cell; wherein the first surface is opposite to the printing surface, and the second surface is opposite to the printing surface;

[0027] A paste is applied to the screen printing plate and printed onto the surface to be printed; wherein, the paste enters the overlapping printing hole from one end exposed on the second surface, and then enters the grid line main body printing hole through the overlapping printing hole; the paste flows out from one end exposed on the first surface through the overlapping printing hole and is printed on the overlapping printing area, and the paste also flows out from one end exposed on the first surface through the grid line main body printing hole and is printed on the sub-grid printing area or the main grid printing area;

[0028] The paste on the surface to be printed is sintered; wherein, the paste on the overlapping printing area is sintered to obtain an overlapping structure; the paste on the sub-grid printing area is sintered to obtain a sub-grid, or the paste on the main grid printing area is sintered to obtain a main grid.

[0029] In a possible implementation of the third aspect, the solid content of the slurry is 85% to 87%;

[0030] And / or, prior to the step of placing the screen printing plate on the printing surface of the solar cell, the method of producing the solar cell further includes the following steps:

[0031] The main grid is fabricated on the main grid printing area of ​​the surface to be printed;

[0032] In the step of applying paste to the screen and printing the paste onto the surface to be printed, the paste is printed on the sub-grid printing area;

[0033] In the step of sintering the paste on the surface to be printed, the paste on the sub-grid printing area is sintered to obtain a sub-grid; the sub-grid overlaps with the main grid through the overlapping structure.

[0034] Fourthly, embodiments of this application disclose a solar cell, comprising:

[0035] Battery body; and

[0036] The grid line is disposed on the surface of the battery body and electrically connected to the battery body. The grid line includes a main grid, an overlapping structure, and a sub-grid. The overlapping structure is disposed at the intersection of the sub-grid and the main grid. The overlapping structure is configured such that the sub-grid overlaps the main grid. The height of the overlapping structure is greater than the height of the sub-grid or the main grid. The grid line is manufactured using the solar cell manufacturing method as described in the third aspect.

[0037] In a possible implementation of the fourth aspect, the height of the overlapping structure is 6μm to 9μm; the height of the sub-gate is 3μm to 7μm.

[0038] And / or, the width of the widest part of the overlapping structure is greater than the width of the sub-gate;

[0039] And / or, the width of the widest part of the overlapping structure is 50μm to 60μm, and the width of the sub-gate is 16μm to 23μm.

[0040] Fifthly, embodiments of this application disclose a photovoltaic module comprising a plurality of parallel and / or series-connected solar cells, at least one of which is the solar cell described in the fourth aspect.

[0041] Compared with the prior art, the beneficial effects of this application are: the overlapping printed holes in the screen printing plate penetrate the film body, while one end of the main printed hole of the grid line is exposed on the first surface, and the other end of the main printed hole of the grid line is located within the film body. The depth of the overlapping printed holes is consistent with the thickness of the film body, while the depth of the main printed holes of the grid line is less than the thickness of the film body. In other words, the depth of the overlapping printed holes is greater than the depth of the main printed holes of the grid line.

[0042] When printing using this screen, the ink is applied to the second surface. When the squeegee applies pressure to the ink area on the second surface and moves, the ink enters the printing hole at the overlap from one end exposed on the second surface. After filling the printing holes at the overlap and the main printing holes of the grid lines, the ink is extruded from the first surface, achieving graphic printing of the ink. Because the printing holes at the overlap are deeper, more ink is printed in them, resulting in a richer ink concentration and better shaping. The resulting overlapping structure has a better morphology and fewer defects due to sufficient metal material, thus allowing the main and secondary grids to form a good overlap. Meanwhile, the printing holes of the main printing lines are shallower, resulting in less ink printing, which helps reduce the amount of ink printed and lower costs.

[0043] In conclusion, using this screen printing method can reduce pulp costs while maintaining high print quality. Attached Figure Description

[0044] 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.

[0045] Figure 1 This is a schematic diagram of printing a solar cell using a screen printing plate as disclosed in an embodiment of this application;

[0046] Figure 2 This is a schematic diagram of the structure of the web version disclosed in the embodiments of this application;

[0047] Figure 3 for Figure 2 Internal structure diagram;

[0048] Figure 4 This is another structural schematic diagram of the web version disclosed in the embodiments of this application;

[0049] Figure 5 for Figure 2 A schematic diagram of the structure of the first side of the screen print;

[0050] Figure 6 For along Figure 5 A sectional view of section AA shown in the figure;

[0051] Figure 7 This is a schematic diagram of the structure of the solar cell disclosed in the embodiments of this application;

[0052] Figure 8 yes Figure 7 The sectional view of section BB shown.

[0053] Explanation of reference numerals in the attached figures:

[0054] 100. Screen printing plate; 110. Thin film body; 111. First side; 112. Second side; 113. First film layer; 114. Second film layer; 120. Grid line printing hole; 121. Grid line main body printing hole; 122. Overlap printing hole; 1221. First printing through hole; 1222. Second printing through hole; 200. Solar cell; 210. Surface to be printed; 211. Sub-grid printing area; 212. Main grid printing area; 213. Overlap printing area; 220. Cell body; 230. Grid line; 231. Main grid; 232. Overlap structure; 233. Sub-grid; 300. Squeegee; 400. Paste. Detailed Implementation

[0055] 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 some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0056] In this application, the terms "upper," "inner," 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.

[0057] 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.

[0058] Furthermore, the terms "set up," "equipped with," "connected," 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.

[0059] 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.

[0060] Screen printing plates are used in the fabrication of solar cell grids to print paste onto specific areas of the surface to be printed. Furthermore, to reduce the manufacturing cost of solar cells, low-solids pastes can be used for printing. Low-solids pastes have a lower metal content, which reduces costs by decreasing the amount of metal material used.

[0061] However, the inventors discovered that when using current screen printing plates with low-solids content pastes to create grid lines, insufficient metal material at the connection between the sub-grid and the main grid results in defective grid line morphology and excessively low grid line height, making it difficult for the sub-grid and main grid to form a good overlap. This makes it extremely easy for the solar cells to break during welding, causing grid breakage and poor contact, leading to low overall efficiency of the photovoltaic module and even collective blackening. These phenomena even hinder the reduction of printing costs for solar cells through the use of low-solids content pastes.

[0062] Based on the above analysis, this application provides a screen printing plate. When printing with this plate, the ink fills the printing holes at the overlap. Because the printing holes at the overlap are deeper, more ink is printed in them, resulting in a richer ink concentration and better shaping. The resulting overlap structure has a better morphology and fewer defects due to sufficient metal material, thus allowing the main grid and sub-grids to form a good overlap. Meanwhile, the printing holes in the main grid lines are shallower, which helps reduce the amount of ink printed and lower costs. In summary, using this screen printing plate can reduce ink costs while maintaining high printing quality.

[0063] The technical solution of the present invention will now be described in conjunction with the embodiments and accompanying drawings.

[0064] Firstly, combining Figures 1 to 3 This application discloses a screen printing plate 100 configured to print on the printing surface 210 of a solar cell 200. The solar cell 200 refers to a solar cell 200 for which grid lines are to be fabricated, such as a solar cell 200 after the fabrication of an anti-reflection film or a passivation film. The printing surface 210 can be the light-receiving surface or the backlighting surface of the solar cell 200. The printing surface 210 has a sub-grid printing area 211, a main grid printing area 212, and an overlap printing area 213. Specifically, the main grid printing area 212 is located on... Figure 3 and Figure 4 The middle section is set along the Y-axis direction, while the secondary grid printing area 211 is located in... Figure 3 and Figure 4 It is set along the X-axis. The overlapping printing area 213 is located at the intersection of the secondary grid printing area 211 and the main grid printing area 212.

[0065] The screen printing plate 100 includes a thin film body 110, the thickness direction of which is as follows: Figure 3and Figure 4 In the Z-axis direction shown, along the thickness direction of the film body 110, the film body 110 has a first surface 111 and a second surface 112 arranged opposite to each other. The first surface 111 is configured to face the surface to be printed 210 when the screen 100 is printing. In other words, the second surface 112 is configured to face away from the surface to be printed 210 when the screen 100 is printing.

[0066] Reference Figure 3 and Figure 4 The thin film body 110 is provided with patterned grid line printing holes 120. The grid line printing holes 120 include interconnected grid line main printing holes 121 and overlapping printing holes 122. The grid line main printing holes 121 are configured to be consistent with the pattern of the sub-grid printing area 211 or the main grid printing area 212. The overlapping printing holes 122 are configured to be consistent with the pattern of the overlapping printing area 213. The term "pattern consistency" means that the patterns are the same.

[0067] In the thickness direction of the thin film body 110, one end of the grid line main body printing hole 121 is exposed on the first surface 111, and the other end of the grid line main body printing hole 121 is located inside the thin film body 110. The overlap printing hole 122 penetrates the thin film body 110, and the two ends of the overlap printing hole 122 are exposed on the first surface 111 and the second surface 112, respectively.

[0068] The overlapping printing hole 122 in the screen printing plate 100 penetrates the film body 110, while one end of the main grid line printing hole 121 is exposed on the first surface 111, and the other end of the main grid line printing hole 121 is located inside the film body 110. The depth of the overlapping printing hole 122 is the same as the thickness of the film body 110, while the depth of the main grid line printing hole 121 is less than the thickness of the film body 110. In other words, the depth of the overlapping printing hole 122 is greater than the depth of the main grid line printing hole 121.

[0069] When printing using the screen 100, the paste is applied to the second surface 112. When the squeegee 300 applies a certain pressure to the paste 400 on the second surface 112 and moves, the paste 400 enters the overlapping printing hole 122 from one end exposed on the second surface 112. After the paste 400 fills the overlapping printing hole 122 and the grid line body printing hole 121, it is pressed out from the first surface 111, thus realizing the graphic printing of the paste 400.

[0070] For example, the screen printing plate 100 is used in one of the more than 200 printing processes of a solar cell. When the main grid line printing hole 121 is configured to match the pattern of the sub-grid printing area 211, the screen printing plate 100 is used to print the sub-grid and the overlapping structure, while the main grid is printed in another printing process using a different screen printing plate, and the sub-grid overlaps with the main grid using the overlapping structure. When the main grid line printing hole 121 is configured to match the pattern of the main grid printing area 212, the screen printing plate 100 is used to print the main grid and the overlapping structure, while the sub-grid is printed in another printing process using a different screen printing plate, and the sub-grid overlaps with the main grid using the overlapping structure.

[0071] Because the printing holes 122 at the overlap are deeper, more paste is printed in the holes 122, resulting in a richer paste concentration and better shaping. The resulting overlap structure has a better morphology and fewer defects due to sufficient metal material, thus enabling the main grid and sub-grid to form a good overlap. Meanwhile, the printing holes 121 on the grid line body are shallower, requiring less paste, which helps reduce the amount of paste needed and lower costs.

[0072] In conclusion, using screen printing with 100 screens can reduce pulp costs while maintaining high print quality.

[0073] In the possible implementation of the first aspect, refer to Figure 5 and Figure 6 The thin film body 110 includes a first film layer 113 and a second film layer 114.

[0074] The first film layer 113 is configured to face the surface to be printed 210 during printing on the screen 100. A grid line main printing hole 121 is provided on the first film layer 113 and extends through the thickness direction of the first film layer 113, as shown in the image. Figure 6 The Z0-Z1 direction is shown in the figure. A first printed through hole 1221 penetrating the thickness direction of the first film layer 113 is also provided on the first film layer 113. The first printed through hole 1221 is configured to match the pattern of the printing area 213 at the overlap.

[0075] The second film layer 114 is stacked on the first film layer 113. A second printed through-hole 1222 penetrating the thickness direction of the second film layer 114 is provided on the second film layer 114. The thickness direction of the second film layer 114 is as follows: Figure 6 The Z0-Z1 direction is shown. The second printed through-hole 1222 is configured to correspond to the pattern of the overlapping printed area 213. The second printed through-hole 1222 is superimposed on the first printed through-hole 1221 and combined with the first printed through-hole 1221 to form the overlapping printed hole 122.

[0076] The screen printing plate 100 forms a grid line main body printing hole 121 and a first printing through hole 1221 on a first film layer 113, and a second printing through hole 1222 on a second film layer 114. By stacking the first film layer 113 and the second film layer 114, the first printing through hole 1221 and the second printing through hole 1222 combine to form an overlap printing hole 122 with a depth greater than the grid line main body printing hole 121. This reduces the manufacturing difficulty of the overlap printing hole 122. On the other hand, a thinner first film layer 113 is stacked with a thinner second film layer 114 to obtain a thin film body 110 of the required thickness. When using laser drilling to create the grid line main body printing hole 121 and the overlap printing hole 122, precise drilling is more easily achieved on the thinner first film layer 113 and the second film layer 114.

[0077] Preferably, the first film layer 113 is a first PI film; and / or, the second film layer 114 is a second PI film. PI (Polyimide) film, compared to films made of other materials, allows for precise fabrication of grid line printing holes 120 using laser perforation.

[0078] The thickness of the first film layer 113 should not be less than 2 μm to avoid insufficient depth of the gate line main body printed hole 121 and the first printed through hole 1221 provided on the first film layer 113; the thickness of the first film layer 113 should also not be greater than 4 μm to avoid difficulty in accurately opening the gate line main body printed hole 121 and the first printed through hole 1221 due to excessive thickness of the first film layer 113. Preferably, the thickness of the first film layer 113 is 2 μm to 4 μm, including any value within this thickness range, such as 2 μm, 3 μm or 4 μm, which can both meet the depth requirements of the gate line main body printed hole 121 and the first printed through hole 1221 and enable accurate opening of the gate line main body printed hole 121 and the first printed through hole 1221.

[0079] The thickness of the second film layer 114 should not be less than 1 μm to avoid insufficient depth of the second printed via 1222 on the second film layer 114; the thickness of the second film layer 114 should also not be greater than 3 μm to avoid difficulty in accurately opening the second printed via 1222 due to excessive thickness of the second film layer 114. The thickness of the second film layer 114 is 1 μm to 3 μm, including any value within this thickness range, such as 1 μm, 2 μm or 3 μm, which can both meet the depth requirement of the second printed via 1222 and allow for accurate opening of the second printed via 1222.

[0080] In one possible implementation of the first aspect, the main printing hole 121 of the grid line is configured to correspond to the pattern of the sub-grid printing area 211. In other words, the main printing hole 121 of the grid line is used to print the sub-grid. Since the solid content of the paste used for printing the sub-grid is higher than that of the paste used for printing the main grid, when making an overlapping structure of the same height, the printing height required for the paste used for printing the sub-grid will be lower than that required for the paste used for printing the main grid. In other words, the screen 100 prints the sub-grid and the overlapping structure simultaneously, which reduces the requirement for the depth of the printing hole 122 at the overlapping point, further reducing the thickness requirement for the film body 110. A thinner film body 110 can be used to reduce the difficulty of opening the printing hole 122 at the overlapping point.

[0081] Furthermore, the width of the widest point of the overlapping printed hole 122 is greater than the width of the main printed hole 121 of the grid line. In other words, the width of the widest point of the overlapping mechanism printed by the overlapping printed hole 122 is greater than that of the sub-grid.

[0082] Furthermore, referring to Figure 5 The length direction of the printed hole 122 at the overlap is in Figure 5 In the X0-X1 direction, the width direction of the printing hole 122 at the overlap and the printing hole 121 of the grid line body is as follows: Figure 5 The Y0-Y1 direction is shown. Along the length of the overlapping printed hole 122, the width of the overlapping printed hole 122 decreases from the middle to both ends. The width of the overlapping structure printed by the overlapping printed hole 122 also decreases from the middle to both ends. By using the middle of the overlapping structure to overlap the sub-gate and the main gate, a better overlapping effect can be obtained. The reduction at both ends of the overlapping structure can reduce the light-blocking area and form a good connection effect with the sub-gate.

[0083] The width of the widest point of the printing hole 122 at the overlap should not be too high, so as to avoid the printed overlap structure being too wide and causing serious light shading; the width of the widest point of the printing hole 122 at the overlap should also not be too narrow, so as to avoid the printed overlap structure being too narrow and affecting the overlap effect. Preferably, the width of the widest point of the printing hole 122 at the overlap is 40μm to 53μm, which can save the amount of ink to print, and the printed overlap structure can have a good overlap effect without excessive light shading.

[0084] The width of the printed aperture 121 of the main grid line should not be too wide, so as not to make the printed grid line too wide and affect the light blocking. The width of the printed aperture 121 of the main grid line should not be too narrow, so as not to make the printed grid line too narrow and affect the collection of charge carriers. The width of the printed aperture 121 of the main grid line is 15μm to 17μm, including any value within this width range, such as 15μm, 16μm or 17μm. This can save the amount of paste to be printed, and the printed sub-grid can have a good charge carrier collection effect without excessive light blocking.

[0085] Secondly, embodiments of this application disclose a method for manufacturing a screen printing plate as described in the first aspect, comprising the following steps:

[0086] Patterned grid lines are printed by directional openings on the thin film body.

[0087] In this manufacturing method, the overlapping printed holes in the screen printing plate penetrate the film body, while one end of the main printed hole of the grid line is exposed on the first surface, and the other end of the main printed hole of the grid line is located within the film body. The depth of the overlapping printed holes is the same as the thickness of the film body, while the depth of the main printed holes of the grid line is less than the thickness of the film body. In other words, the depth of the overlapping printed holes is greater than the depth of the main printed holes of the grid line.

[0088] When using this screen printing plate, the deeper printing holes at the overlap allow for a greater amount of ink to be printed, resulting in a richer ink concentration and better shaping. The resulting overlap structure, with ample metal material, has a better morphology and fewer defects, thus enabling a good overlap between the main and secondary grids. Conversely, the shallower printing holes in the main grid lines result in less ink printing, reducing ink usage and costs. Printing with a screen printing plate manufactured using this method can both reduce ink costs and achieve high print quality.

[0089] In a possible implementation of the second aspect, the step of directionally opening holes in the thin film body to obtain patterned grid line printed holes includes:

[0090] Laser-guided drilling is used to obtain the main printed holes of the grid lines and the first printed through holes on the first film layer; wherein, the main printed holes of the grid lines and the first printed through holes both penetrate the thickness direction of the first film layer, and the pattern of the first printed through hole is consistent with the pattern of the printing area at the overlap.

[0091] A second film layer is superimposed on a first film layer; wherein the second film layer and the first film layer are adsorbed and bonded in a vacuum environment, and the edges of the second film layer and the edges of the first film layer are bonded together with an adhesive.

[0092] A second printed through-hole is obtained by laser-directed drilling on the second film layer; wherein the second printed through-hole penetrates the thickness direction of the second film layer, and the pattern of the second printed through-hole is consistent with that of the printing area at the overlap. The second printed through-hole and the first printed through-hole are stacked to form the printing hole at the overlap.

[0093] The screen printing method involves laser-directed drilling on a first film layer to obtain the main printed holes for the grid lines and the first printed through-holes. Then, a second film layer and the first film layer are bonded together using vacuum adsorption, avoiding the introduction of external substances, such as adhesives, into the drilling area, thus improving the drilling accuracy. The edges of the second film layer and the first film layer are bonded together using adhesive; no drilling is performed in the edge areas. Using adhesive ensures the adhesion between the first and second film layers. Furthermore, by stacking the first and second film layers, laser-directed drilling is performed on the second film layer to obtain the second printed through-holes. The combination of the first and second printed through-holes creates overlapping printed holes with a depth greater than the main printed holes for the grid lines, reducing the difficulty of manufacturing the overlapping printed holes. On the other hand, a thinner first film layer is stacked with a thinner second film layer to obtain a film body of the required thickness. When performing laser-directed drilling on the thinner first and second film layers, a lower-power laser, such as a picosecond laser with a power ≤5W, can be used, thereby reducing laser damage to the first and second film layers and improving drilling accuracy.

[0094] Thirdly, embodiments of this application disclose a method for producing solar cells, which uses a screen as described in the first aspect to produce solar cells, or uses a screen obtained by the manufacturing method described in the second aspect to produce solar cells.

[0095] The method for producing this solar cell includes the following steps:

[0096] The screen is placed on the surface of the solar cell to be printed; wherein the first side faces the surface to be printed, and the second side faces away from the surface to be printed.

[0097] The paste is applied to the screen and printed onto the surface to be printed; wherein, the paste enters the printing hole at the overlap point from one end exposed on the second side, and then enters the main printing hole of the grid line through the printing hole at the overlap point; the paste flows out from one end exposed on the first side of the printing hole at the overlap point and is printed on the printing area at the overlap point, and the paste also flows out from one end exposed on the first side of the printing hole of the main printing hole of the grid line and is printed on the secondary grid printing area or the main grid printing area;

[0098] The paste on the printing surface is sintered; among them, the paste on the overlapping printing area is sintered to obtain an overlapping structure; the paste on the sub-grid printing area is sintered to obtain a sub-grid, or the paste on the main grid printing area is sintered to obtain a main grid.

[0099] The solar cells produced by this method have deeper printed holes at the overlap joints, resulting in a larger and more concentrated paste, better shaping, and a better morphology with fewer defects due to sufficient metal material. This allows for a better overlap between the main and sub-grids. Conversely, the shallower printed holes in the main grid lines result in less paste, reducing the amount of paste needed and lowering costs. In summary, this method reduces the manufacturing cost of the solar cell and provides high-quality printing of the overlap structure.

[0100] Preferably, the solid content of the paste is 85% to 87%, including any value within this range, such as 85%, 86%, or 87%. By reducing the solid content of the paste, and since the solid components of the paste are mainly metallic materials, such as silver, the cost of the paste can be reduced while maintaining good printing results. In other words, using this paste can reduce the manufacturing cost of solar cells, and when used with the screen printing plate, it can also achieve good printing results.

[0101] Optionally, prior to the step of placing the screen on the printing surface of the solar cell, the method for producing the solar cell further includes the following steps:

[0102] The main grid is fabricated on the main grid printing area of ​​the surface to be printed;

[0103] In the step of applying paste to a screen and printing the paste onto the surface to be printed, the paste is printed on the sub-grid printing area;

[0104] In the step of sintering the paste on the printing surface, the paste on the sub-grid printing area is sintered to obtain the sub-grid; the sub-grid overlaps with the main grid through an overlapping structure.

[0105] In other words, this production method first manufactures the main grid, and then uses the paste used for printing the secondary grid to simultaneously manufacture the secondary grid and the overlapping structure.

[0106] Fourthly, refer to Figure 7 and Figure 8 This application discloses a solar cell 200, including a cell body 220 and grid lines 230. The grid lines 230 are disposed on the surface of the cell body 220 and electrically connected to the cell body 220. The grid lines 230 include a main grid 231, an overlapping structure 232, and a sub-grid 233. The overlapping structure 232 is disposed at the intersection of the sub-grid 233 and the main grid 231. The overlapping structure 232 is configured such that the sub-grid 233 overlaps the main grid 231. The height of the overlapping structure 232 is greater than the height of either the sub-grid 233 or the main grid 231, and the height direction is as follows: Figure 8 The Z0-Z1 direction is shown. The grid lines 230 are manufactured using the production method of the solar cell 200 as described in the third aspect.

[0107] It should be noted that, although Figure 8 In the solar cell 200, the main grid 231, the overlapping structure 232 and the sub-grid 233 are provided on only one surface, but the solar cell 200 can also have the main grid 231, the overlapping structure 232 and the sub-grid 233 provided on both surfaces.

[0108] Optionally, the battery type of the battery body can be a passivated contact solar cell, a back contact solar cell, a heterojunction solar cell, or a perovskite solar cell. Taking one type of passivated contact solar cell as an example, the passivated contact solar cell includes a silicon substrate, a diffusion layer, a dielectric layer, a doped polycrystalline silicon layer, a first functional film, and a second functional film. The diffusion layer and the first functional film are sequentially stacked on the silicon substrate in a direction away from the silicon substrate. The dielectric layer, the doped polycrystalline silicon layer, and the second functional film are sequentially stacked on the silicon substrate in a direction away from the silicon substrate. The grid lines penetrate the first functional film and make ohmic contact with the diffusion layer, or the grid lines penetrate the second functional film and make ohmic contact with the doped polycrystalline silicon layer.

[0109] In a possible implementation of the fourth aspect, the height of the overlap structure 232 is 6μm to 9μm, including any value within this height range, such as 6μm, 8μm, or 9μm. This height of the overlap structure 232 can achieve a good overlap effect while saving paste. The height of the sub-gate 233 is 3μm to 7μm, including any value within this height range, such as 3μm, 5μm, or 7μm. This height of the sub-gate 233 can save paste while also having a good carrier collection effect.

[0110] Furthermore, the width of the widest part of the overlapping structure 232 is greater than the width of the sub-gate 233. By using the widest part of the overlapping structure 232 to overlap the main gate 231 and the sub-gate 233, a good overlapping effect can be formed.

[0111] Preferably, the width of the widest part of the overlapping structure 232 is 50μm to 60μm, including any value within this range, such as 50μm, 55μm, or 60μm. This overlapping structure 232 does not excessively block light, saves the amount of ink required for printing, and also has a good overlapping effect. The width of the sub-gate 233 is 15μm to 23μm, including any value within this range, such as 16μm, 19μm, or 23μm. This sub-gate 233 does not excessively block light, saves the amount of ink required for printing, and also has a good carrier collection effect.

[0112] Fifthly, embodiments of this application disclose a photovoltaic module comprising a plurality of parallel and / or series-connected solar cells, at least one of which is the solar cell described in the fourth aspect. Due to the high printing quality of the solar cell's overlapping structure, the sub-busbars and main busbars achieve a good overlapping effect, thereby reducing grid breakage and poor contact during solar cell welding. The photovoltaic module with this solar cell has the advantages of high overall efficiency and high stability.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A screen, characterized by, The screen plate is configured to print a to-be-printed surface of a solar cell, the to-be-printed surface having a sub-grid printing area, a main-grid printing area, and an overlap printing area at an intersection of the sub-grid printing area and the main-grid printing area; The screen plate includes a thin film body having a first surface and a second surface arranged opposite to each other in a thickness direction of the thin film body, the first surface being configured to face the to-be-printed surface when the screen plate is printing; The thin film body is provided with patterned grid line printing holes, the grid line printing holes including connected grid line body printing holes and overlap printing holes, the grid line body printing holes being configured to be consistent with a pattern of the sub-grid printing area or the main-grid printing area, and the overlap printing holes being configured to be consistent with a pattern of the overlap printing area; In the thickness direction of the thin film body, one end of the grid line body printing hole is exposed to the first surface, and the other end of the grid line body printing hole is located in the thin film body; the overlap printing hole penetrates through the thin film body, and both ends of the overlap printing hole are exposed to the first surface and the second surface, respectively.

2. The screen printing screen of claim 1, wherein The thin film body includes: a first film layer configured to face the to-be-printed surface when the screen plate is printing; the grid line body printing holes are arranged on the first film layer and penetrate through a thickness direction of the first film layer, and the first film layer is further provided with first printing through holes penetrating through the thickness direction of the first film layer, the first printing through holes being configured to be consistent with the pattern of the overlap printing area; and a second film layer stacked on the first film layer, the second film layer being provided with second printing through holes penetrating through a thickness direction of the second film layer, the second printing through holes being configured to be consistent with the pattern of the overlap printing area; the second printing through holes are stacked on the first printing through holes and combined with the first printing through holes to form the overlap printing hole.

3. The screen printing screen of claim 2, wherein The first film layer is a first PI film; and / or, the second film layer is a second PI film; and / or, the thickness of the first film layer is 2 μm to 4 μm; and / or, the thickness of the second film layer is 1 μm to 3 μm.

4. The screen printing screen according to any one of claims 1 to 3, characterized in that The grid line body printing holes are configured to be consistent with the pattern of the sub-grid printing area, and a width of the widest part of the overlap printing hole is greater than a width of the grid line body printing hole; and / or, along a length direction of the overlap printing hole, the width of the overlap printing hole decreases from a middle of the overlap printing hole to both ends.

5. The screen printing screen of claim 4, wherein The width of the widest part of the overlap printing hole is 40 μm to 53 μm, and the width of the grid line body printing hole is 15 μm to 17 μm.

6. A method of manufacturing the screen as claimed in any one of claims 1 to 5, characterized in that, The method includes the following steps: directly opening holes on the thin film body to obtain the patterned grid line printing holes.

7. The method of claim 6, wherein The step of directly opening holes on the thin film body to obtain the patterned grid line printing holes includes: The laser is used to direct the perforation on the first film layer to obtain the grid line body printing hole and the first printing through hole; wherein, the grid line body printing hole and the first printing through hole both penetrate the thickness direction of the first film layer, and the first printing through hole is consistent with the pattern of the overlap printing area; The second film layer is stacked on the first film layer; wherein, the second film layer and the first film layer are adsorbed and bonded in a vacuum environment, and the edges of the second film layer and the edges of the first film layer are bonded by using an adhesive; The laser is used to direct the perforation on the second film layer to obtain the second printing through hole; wherein, the second printing through hole penetrates the thickness direction of the second film layer, and the second printing through hole is consistent with the pattern of the overlap printing area, and the second printing through hole and the first printing through hole are stacked to form the overlap printing hole.

8. A method for producing a solar cell, characterized by, The solar cell is produced by using the screen printing plate according to any one of claims 1 to 5, or by using the screen printing plate prepared by the manufacturing method according to claim 6 or 7; The production method of the solar cell comprises the following steps: The screen printing plate is placed on the printing surface of the solar cell; wherein, the first surface is opposite to the printing surface, and the second surface is away from the printing surface; The paste is coated on the screen printing plate to print the paste on the printing surface; wherein, the paste enters the overlap printing hole from one end of the overlap printing hole exposed to the second surface, and then the paste enters the grid line body printing hole through the overlap printing hole; the paste flows out from one end of the overlap printing hole exposed to the first surface to be printed on the overlap printing area, and the paste also flows out from one end of the grid line body printing hole exposed to the first surface to be printed on the auxiliary grid printing area or the main grid printing area; The paste on the printing surface is sintered; wherein, the paste on the overlap printing area is sintered to form an overlap structure; the paste on the auxiliary grid printing area is sintered to form an auxiliary grid, or the paste on the main grid printing area is sintered to form a main grid.

9. The method for producing a solar cell according to claim 8, wherein The solid content of the paste is 85% to 87%; And / or, before the step of placing the screen printing plate on the printing surface of the solar cell, the production method of the solar cell further comprises the following steps: A main grid is made on the main grid printing area of the printing surface; In the step of coating the paste on the screen printing plate to print the paste on the printing surface, the paste is printed on the auxiliary grid printing area; In the step of sintering the paste on the printing surface, the paste on the auxiliary grid printing area is sintered to form an auxiliary grid; the auxiliary grid is overlapped with the main grid through the overlap structure.

10. A solar cell, characterized by Comprise: A cell body; And The grid lines are arranged on the surface of the battery body and are electrically connected to the battery body, and the grid lines comprise a main grid, a lap joint structure and a sub-grid, the lap joint structure is arranged at the intersection of the sub-grid and the main grid, the lap joint structure is configured to lap the sub-grid on the main grid, and the height of the lap joint structure is greater than the height of the sub-grid or the main grid.

11. The solar cell according to claim 10, characterized in that, The height of the lap joint structure is 6 μm to 9 μm, and the height of the sub-grid is 3 μm to 7 μm. And / or, the width of the widest part of the lap joint structure is greater than the width of the sub-grid. And / or, the width of the widest part of the lap joint structure is 50 μm to 60 μm, and the width of the sub-grid is 16 μm to 23 μm.

12. A photovoltaic module, characterized by The solar cell comprises a plurality of solar cells connected in parallel and / or in series, and at least one of the solar cells is the solar cell according to claim 10 or 11.

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