Solar cell, preparation method thereof and photovoltaic module

Abstract

A solar cell includes a cell substrate, a conductive gate line and an alignment pattern. The battery substrate comprises a first surface and a second surface which are opposite, wherein at least one of the first surface and the second surface is a target surface. The conductive gate line includes a first metal layer disposed on the target surface. The alignment pattern is arranged on the target surface and located in the area where the conductive grid lines are located, and comprises a second metal layer. The second metal layer is connected with the first metal layer. The first metal layer and the second metal layer are used for transmitting carriers with the same polarity. The first metal layer of the conductive grid line is not disconnected in the region of the alignment pattern, and collection and transmission of carriers in the region of the alignment pattern are not affected. The invention also provides a photovoltaic module comprising the solar cell and a preparation method of the solar cell.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and more specifically, to a solar cell and a preparation method thereof, including a photovoltaic module of the solar cell. Background Art

[0002] The production process of solar cells generally includes a laser scribing step. During the laser scribing process, in addition to scribing the area for preparing the electrode, it is also necessary to scribble the MARK point (laser alignment point), and then accurately align the MARK point in the process of screen printing the slurry to form the metal electrode, so that the slurry completely covers the laser grooved area, thereby forming an aluminum-silicon alloy during the subsequent high-temperature sintering process for the extraction of current. Since the thickness of the screen-printed metal layer is usually thicker, usually reaching 10 to 50 μm. However, this thickness of metal printed on the MARK point is very likely to completely cover the laser grooved part of the MARK point, thereby submerging the MARK point, and then making it impossible for the camera to effectively capture the MARK point, and unable to achieve precise alignment of the battery in subsequent processes. Therefore, in order to facilitate the marking and tracking of the lines of the cell after screen printing, it is usually necessary to design a separate screen and set a shield at the position corresponding to the MARK point to prevent the paste from being printed on the MARK point; or, it is necessary to manually drip the sealing slurry at the position corresponding to the MARK point on each screen printing screen to form a screen glue point. During screen printing, the screen glue point cannot penetrate the slurry printing, thereby forming a mark point on the grid line of the cell where the slurry is not printed. When printing different lines, the position and number of the screen glue points are different, thus forming different marking patterns, and then distinguishing the printed lines.

[0003] Whether using a screen or manually dripping the sealing paste, a partition will be created at the grid line on the cell, thus isolating the grid line, disconnecting the carrier transmission path, and forming a short circuit at the partition. The carrier needs to be guided out through other non-disconnected paths, resulting in a longer carrier transmission path, and current loss during transmission, affecting power generation efficiency. At the same time, using traditional screen printing technology to print the paste at the partition so that the grid lines at both ends of the partition are connected, the production cost is huge. Summary of the invention

[0004] In view of this, the present application provides a solar cell, in which the metal layer of the conductive grid line is not disconnected in the area of ​​the alignment pattern, which will not affect the collection and transmission of carriers in the area of ​​the alignment pattern, avoid the formation of dead zones in the area of ​​the alignment pattern, and effectively improve the power generation efficiency of the battery cell.

[0005] A solar cell comprising:

[0006] a battery substrate, the battery substrate comprising a first surface and a second surface opposite to each other, wherein at least one of the first surface and the second surface is a target surface;

[0007] A conductive grid line, located on the target surface and comprising a first metal layer disposed on the target surface;

[0008] An alignment pattern, arranged on the target surface and located in the area where the conductive gate line is located, the alignment pattern comprising a second metal layer;

[0009] The second metal layer is connected to the first metal layer, and the first metal layer and the second metal layer are used to transmit carriers with the same polarity.

[0010] In the present application, a second metal layer is set in the alignment pattern, and the conductive grid lines at the partition are connected through the second metal layer, which will not affect the collection and transmission of carriers in the alignment pattern area. Compared with the method of connecting the two ends of the partition through other non-disconnection paths, the conductive path is shortened, the current flow path is saved, the current loss is reduced, and the power generation efficiency of the battery cell is improved.

[0011] As a possible implementation, the alignment pattern includes a groove that is sunken relative to the target surface, the groove wall includes a bottom wall and a side wall surrounding and connecting the bottom wall, and the second metal layer is attached to the bottom wall and the side wall; along the thickness direction of the battery substrate, the second metal layer has a height difference with the first metal layer.

[0012] Since there is a height difference between the first metal layer and the second metal layer, when the camera captures the alignment pattern from above the battery cell, there will be a large color difference between the second metal layer of the alignment pattern and the first metal layer of the conductive grid line due to light. Therefore, there is a strong contrast between the alignment pattern and its surrounding parts, which can ensure that the alignment pattern can be clearly captured by the camera and will not affect the alignment of the solar cell.

[0013] As a possible implementation manner, along the thickness direction of the battery substrate, the second metal layer on the bottom wall has the same thickness as the first metal layer; and / or,

[0014] The thickness of the second metal layer and the first metal layer are both in the range of 0.5 μm to 10 μm; and / or,

[0015] Along the thickness direction of the battery substrate, the height difference ΔH between the first metal layer and the second metal layer on the bottom wall is 0.5 μm to 50 μm, wherein ΔH is the height difference between the highest point of the first metal layer and the lowest point of the second metal layer on the bottom wall along the thickness direction of the battery substrate; and / or,

[0016] A carrier transport layer is also arranged between the bottom wall and the second metal layer on the bottom wall.

[0017] The carrier transport layer is mainly used to generate photogenerated current under illumination conditions and transport photogenerated carriers. As a possible implementation scheme, when the solar cell has a tunnel oxide passivated contact (Tunnel Oxide Passivated Contact, Topcon) structure, the carrier transport layer includes a tunnel oxide layer, a doped polysilicon layer, and the second metal layer is arranged on the doped polysilicon layer; or the carrier transport layer includes a tunnel oxide layer, a doped polysilicon layer and an insulating passivation layer or a passivation anti-reflection layer, and the second metal layer is arranged on the passivation layer or the passivation anti-reflection layer; or, the carrier transport layer includes a tunnel oxide layer, a doped polysilicon layer and a transparent conductive oxide layer (TCO, transparent conductive oxide) layer, and the second metal layer is arranged on the TCO layer. As a possible implementation scheme, when the solar cell has a heterojunction structure (HJT, Heterojunction), the carrier transport layer includes an intrinsic amorphous silicon layer, a doped amorphous silicon layer and a transparent conductive layer.

[0018] As a possible implementation, the alignment pattern further includes a pattern portion disposed in the groove, the pattern portion being protruding on the bottom wall and spaced apart from the side wall;

[0019] The pattern portion includes a top surface facing away from the bottom wall and a side surface connected to the top surface, wherein the side surface is connected between the bottom wall and the top surface.

[0020] As a possible implementation manner, the second metal layer is also provided on the top surface and the side surface;

[0021] Along the thickness direction of the battery substrate, the second metal layer on the top surface has a flush surface with the first metal layer; and / or,

[0022] Along the thickness direction of the battery substrate, the second metal layer on the top surface has the same thickness as the first metal layer; and / or,

[0023] The thickness of the second metal layer and the first metal layer on the pattern portion are both in the range of 0.5 μm to 10 μm; and / or,

[0024] Along the thickness direction of the battery substrate, the height difference ΔH between the second metal layer on the top surface and the second metal layer on the bottom wall is 0.5 μm to 50 μm, wherein ΔH is the height difference between the highest point of the second metal layer on the top surface and the lowest point of the second metal layer on the bottom wall along the thickness direction of the battery substrate; and / or,

[0025] A carrier transport layer is further provided between the top surface and the second metal layer on the top surface; and / or,

[0026] A groove recessed relative to the top surface is formed in the pattern portion, and a metal layer connected to the second metal layer is formed on the groove wall.

[0027] As a possible implementation manner, the second metal layer and the first metal layer both include a first sub-metal layer and a second sub-metal layer which are stacked, wherein the first sub-metal layer is located between the battery substrate and the second sub-metal layer;

[0028] The standard electrode potential difference between the first sub-metal layer and the second sub-metal layer is 0.1 to 3.5 V; and / or,

[0029] The material of the first sub-metal layer includes one or more of Al, Zn, Fe, Co, Mg, Cu, Ag and alloys thereof; and / or,

[0030] The material of the second sub-metal layer includes one or more of Cu, Ni, Cr, Ti, W, Mo, Ag, Sn and alloys thereof; and / or,

[0031] The thickness of the second sub-metal layer is less than or equal to 10% of the thickness of the first metal layer; and / or,

[0032] The first sub-metal layer is composed of two or more sub-layers, and the material of each sub-layer is selected from one or more of Al, Zn, Fe, Co, Mg, Cu, Ag and alloys thereof.

[0033] As a possible implementation manner, a buffer layer is further provided between the first sub-metal layer and the battery substrate, and the buffer layer includes one or more combinations of metal oxides, metal nitrides, metal fluorides, metal silicides and metals;

[0034] The metal oxides include AZO, TiO x 、Cu2O、MgO x 、TaO x , VO x CrO x 、SnO2、B:ZnO、CdO x and MoO x One or more combinations of; and / or,

[0035] The metal nitride includes TiN x and TiO x N y One or more combinations of; and / or,

[0036] The metal fluoride comprises one or more combinations of MgF2, LiF, YF3 and CeF3; and / or,

[0037] The metal silicide comprises one or more combinations of TiSi2, TaSi2, MOSi2, CoSi2, Ni2Si and WSi2; and / or,

[0038] The metal includes one or more combinations of Ni, Ti, Cr, Cu, W, Mo and Ag.

[0039] In a second aspect, the present application provides a method for preparing a solar cell, comprising:

[0040] providing a battery substrate, the battery substrate comprising a first surface and a second surface opposite to each other, wherein at least one of the first surface and the second surface is a target surface;

[0041] forming a groove of an alignment pattern on the target surface;

[0042] A first metal layer of conductive grid lines is formed on the target surface, and a second metal layer is formed on the groove wall of the groove, the first metal layer is connected to the second metal layer, and along the thickness direction of the battery substrate, the first metal layer and the second metal layer have a height difference.

[0043] As a possible implementation, when the groove is formed, a part of the battery substrate is retained in the space surrounded by the groove to form a pattern portion protruding on the bottom wall of the groove; and / or,

[0044] The metal layer on the bottom wall of the groove has the same thickness as the first metal layer; and / or,

[0045] The thickness of the second metal layer and the first metal layer are both in the range of 0.5 μm to 10 μm; and / or,

[0046] Along the thickness direction of the battery substrate, the height difference ΔH between the first metal layer and the metal layer on the bottom wall of the groove is 0.5μm to 50μm, where ΔH is the height difference between the highest point of the first metal layer and the lowest point of the metal layer on the bottom wall of the groove along the thickness direction of the battery substrate.

[0047] In a third aspect, the present application provides a photovoltaic module, comprising a glass cover plate, a film layer, a battery layer, a film layer and a transparent or opaque back plate stacked in sequence, wherein the solar cell comprises a plurality of solar cells described in the first aspect or solar cells prepared by the preparation method described in the second aspect connected in series. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a partial top view schematic diagram of the conductive grid line of the solar cell according to the first embodiment of the present application.

[0049] Figure 2for Figure 1 Schematic diagram of the cross section taken along section line AA.

[0050] Figure 3 It is a partial top view schematic diagram of the conductive grid lines of the solar cell according to the second embodiment of the present application.

[0051] Figure 4 for Figure 3 Schematic diagram of the cross section taken along section line BB.

[0052] Figure 5 It is a partial top view schematic diagram of the conductive grid lines of the solar cell according to the third embodiment of the present application.

[0053] Figure 6 It is a partial top view schematic diagram of the conductive grid lines of the solar cell according to the fourth embodiment of the present application.

[0054] Figure 7 It is a partial top view schematic diagram of the conductive grid lines of the solar cell according to the fifth embodiment of the present application.

[0055] Description of main component symbols:

[0056] Battery substrate 10

[0057] Conductive grid line 30

[0058] Positioning Graphics 50

[0059] First surface 11

[0060] Second surface 12

[0061] Groove 51

[0062] First metal layer 33

[0063] Second metal layer 53

[0064] Bottom wall 511

[0065] Side wall 513

[0066] Pattern 52

[0067] The first alignment pattern 50a

[0068] Second alignment pattern 50b

[0069] Top 521

[0070] Side 523 DETAILED DESCRIPTION

[0071] At present, the existing technology processes alignment points on the battery cell, which will form grooves and pattern areas on the battery cell. The grooves will isolate the pattern area, thereby forming an island on the battery cell, thereby isolating the gate line, disconnecting the carrier transmission path, and forming a short circuit at the partition. The carriers need to be exported through other non-disconnection paths, which leads to the increase of the carrier transmission path. Current will be lost during the transmission process, affecting the power generation efficiency.

[0072] The present application provides a solar cell, which adopts a coating process to form a conductive grid line and a metal layer of an alignment pattern in one piece, and the metal layer of the alignment pattern is connected to the metal layer of the conductive grid line. In this way, the metal layer of the conductive grid line is not disconnected in the area of ​​the alignment pattern, which will not affect the collection and transmission of carriers in the area of ​​the alignment pattern, avoid the formation of a dead zone in the area of ​​the alignment pattern, and effectively improve the power generation efficiency of the battery cell.

[0073] Please refer to Figure 1 and Figure 2 The solar cell of the first embodiment of the present application includes a cell substrate 10 , a conductive grid line 30 and an alignment pattern 50 arranged on the cell substrate 10 . Figure 1 Only a part of the area where the conductive gate line 30 is located is shown, and the alignment pattern 50 is arranged in the area where the conductive gate line 30 is located.

[0074] like Figure 2 As shown, the battery substrate 10 includes a first surface 11 and a second surface 12 relative to each other, wherein at least one of the first surface 11 and the second surface 12 is defined as a target surface. One of the first surface 11 and the second surface 12 is a light-receiving surface, and the other is a backlight surface. The embodiment of the present application is described by taking the first surface 11 as the target surface as an example. Although not shown in the figure, a plurality of conductive grid lines 30 and at least one alignment pattern 50 are arranged on the target surface. Each conductive grid line 30 includes a first metal layer 33 arranged on the target surface. The alignment pattern 50 includes a second metal layer 53. The second metal layer 53 is connected to the first metal layer 33. The second metal layer 53 and the first metal layer 33 are integrally formed by a coating process. The coating process can be a process such as physical vapor deposition (e.g., evaporation, magnetron sputtering), chemical vapor deposition, electroplating, screen printing, etc. The first metal layer 33 and the second metal layer 53 are used to transmit carriers of the same polarity. In this way, the first metal layer 33 of the conductive gate line 30 is not disconnected in the region of the alignment pattern 50 , and will not affect the collection and transmission of carriers in the region of the alignment pattern 50 .

[0075] Along the thickness direction of the battery substrate 10, the second metal layer 53 and the first metal layer 33 have a height difference. Figure 2The alignment pattern 50 includes a groove 51 that is recessed relative to the target surface (first surface 11). The second metal layer 53 is attached to the groove wall of the groove 51. There is a large color difference between the second metal layer 53 and the first metal layer 33 due to light. In this way, there is a strong contrast between the alignment pattern 50 and its surrounding parts, so the alignment pattern 50 can be clearly captured by the camera and will not affect the alignment of the solar cell.

[0076] In some embodiments, a carrier transport layer (not shown) is provided at a position of the battery substrate 10 corresponding to the conductive grid line 30. The carrier transport layer is mainly used to generate photocurrent under illumination conditions and transmit photogenerated carriers. The carriers generated by the carrier transport layer are transmitted through the conductive grid line 30. Along the thickness direction of the battery substrate 10, the position of the conductive grid line 30 is aligned with the carrier transport layer. The carrier transport layer is provided between the battery substrate 10 and the conductive grid line 30.

[0077] As a possible implementation scheme, when the solar cell has a tunnel oxide passivated contact (Tunnel Oxide Passivated Contact, Topcon) structure, the carrier transport layer includes a tunnel oxide layer and a doped polysilicon layer, and the conductive gate line 30 is arranged on the doped polysilicon layer; or, the carrier transport layer includes a tunnel oxide layer, a doped polysilicon layer and a transparent conductive oxide (transparent conductive oxide, TCO) layer, and the conductive gate line 30 is arranged on the TCO layer; or, the carrier transport layer includes a tunnel oxide layer, a doped polysilicon layer and an insulating passivation layer or a passivation anti-reflection layer, and the conductive gate line 30 is arranged on the passivation layer or the passivation anti-reflection layer.

[0078] As a possible implementation scheme, when the solar cell has a heterojunction (HJT) structure, the carrier transport layer includes an intrinsic amorphous silicon layer, a doped amorphous silicon layer and a transparent conductive oxide (TCO) layer.

[0079] like Figure 2 As shown, the groove wall of the groove 51 includes a bottom wall 511 and a side wall 513 surrounding and connecting the bottom wall 511, wherein the side wall 513 is connected between the target surface (first surface 11) and the bottom wall 511. A second metal layer 53 is attached to both the bottom wall 511 and the side wall 513, and the second metal layer 53 on the bottom wall 511 is connected to the second metal layer 53 on the side wall 513.

[0080] In addition, a carrier transport layer (not shown) is also provided between the bottom wall 511 of the groove 51 and the second metal layer 53, so that carriers can be generated in the groove 51 area and transmitted through the second metal layer 53. In this way, the conductive grid lines 30 on both sides of the alignment pattern 50 are connected through the second metal layer 53 on the bottom wall 511 and the side wall 513 of the groove 51. Therefore, the carriers generated in the groove 51 area can be transmitted to the conductive grid lines 30 through the second metal layer 53, thereby improving the power generation efficiency of the solar cell and solving the problem that the carriers in the groove 51 area cannot be transmitted. The carriers flowing through the second metal layer 53 of the groove 51 and the first metal layer 33 of the conductive grid lines 30 have the same polarity.

[0081] By setting the second metal layer 53 in the groove 51 of the alignment pattern 50, the conductive grid lines 30 on both sides of the alignment pattern 50 can be electrically connected, so that the carrier transmission path can remain unbroken. In addition, compared with the method of connecting the two ends of the partition through other non-disconnection paths, the method of the present application shortens the conductive path, saves the current flow path, reduces current loss, and improves the power generation efficiency of the solar cell.

[0082] In some embodiments, along the thickness direction of the battery substrate 10 (the distance between the first surface 11 and the second surface 12 is the thickness of the battery substrate 10 ), the second metal layer 53 on the bottom wall 511 and the first metal layer 33 of the conductive grid line 30 have the same thickness.

[0083] It can be understood that in the groove 51, the thickness of the second metal layer 53 on the side wall 513 may be the same as the thickness of the second metal layer 53 on the bottom wall 511, or less than the thickness of the second metal layer 53 on the bottom wall 511. The thickness direction of the second metal layer 53 on the side wall 513 of the groove 51 may be a direction perpendicular to the side wall 513. The thickness of the metal layer involved in the present application may be the average thickness of the metal layer.

[0084] The thickness of the second metal layer 53 in the groove 51 and the first metal layer 33 of the conductive gate line 30 are both in the range of 0.5 μm to 10 μm. Compared with the method of forming the metal layer by screen printing, the thickness of the second metal layer 53 and the first metal layer 33 formed by the nano-plating process is relatively thinner, thereby avoiding the problem of the second metal layer 53 filling the groove 51.

[0085] In some embodiments, along the thickness direction of the battery substrate 10, the height difference ΔH between the first metal layer 33 of the conductive grid line 30 and the second metal layer 53 on the bottom wall 511 of the groove 51 is 0.5 μm to 50 μm, where ΔH refers to: along the thickness direction of the battery substrate 10, the height difference between the highest point of the first metal layer 33 of the conductive grid line 30 and the lowest point of the second metal layer 53 on the bottom wall 511.

[0086] Along the thickness direction of the battery substrate 10, when the second metal layer 53 on the bottom wall 511 and the first metal layer 33 of the conductive grid line 30 have the same thickness, the height difference ΔH between the first metal layer 33 of the conductive grid line 30 and the lowest point of the second metal layer 53 in the groove 51 is substantially equal to the depth of the groove 51 along the thickness direction of the battery substrate 10. That is, in some embodiments, along the thickness direction of the battery substrate 10, the depth of the groove 51 may be 0.5 μm to 50 μm.

[0087] By controlling the height difference between the first metal layer 33 of the conductive grid line 30 and the second metal layer 53 in the groove 51, a large color difference is created between the second metal layer 53 and the first metal layer 33 due to light. Thus, there is a strong contrast between the alignment pattern 50 and its surroundings, ensuring that the alignment pattern 50 can be clearly captured by the camera.

[0088] In the second embodiment, Figure 3 and Figure 4 As shown, the alignment pattern 50 includes not only a groove 51 that is recessed relative to the target surface, but also a pattern portion 52 disposed in the groove 51. The pattern portion 52 is convexly disposed on the bottom wall 511 and is spaced apart from the side wall 513. The groove 51 is equivalent to the removal of a portion of the battery substrate 10 corresponding to the groove 51 area by digging out / etching, while the pattern portion 52 is equivalent to the portion of the battery substrate 10 corresponding to the pattern portion 52 that is not removed and is retained. The pattern portion 52 includes a top surface 521 that is away from the bottom wall 511 and a side surface 523 that is connected to the top surface 521, wherein the side surface 523 is connected between the bottom wall 511 and the top surface 521. In some embodiments, the top surface 521 of the pattern portion 52 is flush with the target surface, but is not limited thereto.

[0089] The second metal layer 53 is also disposed on the top surface 521 and the side surface 523 of the pattern portion 52, and the second metal layer 53 on the surface of the pattern portion 52 is connected to the second metal layer 53 in the groove 51. The second metal layer 53 of the pattern portion 52 and the first metal layer 33 of the conductive gate line 30 are also integrally formed by the coating process.

[0090] In addition, a carrier transport layer (not shown) is provided between the top surface 521 of the pattern portion 52 and the second metal layer 53, so that carriers can be generated in the pattern portion 52 area and transmitted through the second metal layer 53. Therefore, the carriers generated by the pattern portion 52 can be transmitted to the conductive grid line 30 through the second metal layer 53, thereby improving the power generation efficiency of the solar cell and solving the problem that the carriers of the pattern portion 52 cannot be transmitted. The polarity of the carriers flowing through the second metal layer 53 of the groove 51, the second metal layer 53 of the pattern portion 52 and the first metal layer 33 of the conductive grid line 30 is the same.

[0091] In some embodiments, along the thickness direction of the battery substrate 10, a height difference ΔH between the second metal layer 53 on the top surface 521 of the pattern portion 52 and the lowest point of the second metal layer 53 in the groove 51 is 0.5 μm to 50 μm, where ΔH refers to: along the thickness direction of the battery substrate 10, the distance between the highest point of the second metal layer 53 on the top surface 521 and the lowest point of the second metal layer 53 in the groove 51.

[0092] In some embodiments, along the thickness direction of the battery substrate 10, the second metal layer 53 on the top surface 521 of the pattern portion 52 and the first metal layer 33 of the conductive grid line 30 have a flush surface. In this way, the conductive grid line 30 region of the battery substrate 10 is highly uniform and flat.

[0093] In some embodiments, the first metal layer 33 of the conductive gate line 30 has the same thickness as the second metal layer 53 on the top surface 521 of the pattern portion 52. The thickness of the second metal layer 53 on the side surface 523 of the pattern portion 52 may be equal to or less than the thickness of the second metal layer 53 on the top surface 521 of the pattern portion 52.

[0094] The pattern portion 52 located in the groove 51 is formed by retaining a part of the battery substrate 10 in the groove 51 . Thus, due to the height difference, there is also a strong contrast between the groove 51 and the pattern portion 52 , so that the alignment pattern 50 can be captured more quickly.

[0095] In the solar cell provided in the present application, the first metal layer 33 and the second metal layer 53 are prepared to be thinner through a micro-nano metal plating process, so that after the first metal layer 33 covers the area where the conductive grid line 30 is located and the second metal layer 53 covers the area where the alignment pattern 50 is located, the difference in height of the second metal layer 53 in the groove 51 of the alignment pattern 50 and the height of the second metal layer 53 of the pattern portion 52 / the first metal layer 33 of the conductive grid line 30 can still be maintained within a larger range. Due to the large height difference, when the camera captures the alignment pattern 50 from above the solar cell, there will be a large color difference between the second metal layer 53 in the groove 51 area and the second metal layer 53 of the pattern portion 52 / the first metal layer 33 of the conductive grid line 30 due to light reasons. In this way, there is a strong contrast between the alignment pattern 50 and the surrounding parts, so that the alignment pattern 50 can still be clearly captured by the camera without affecting the alignment of the battery cell.

[0096] The solar cell provided by the present application does not need to prepare the metal layer by screen printing conductive paste, so there is no need to specially design a screen printing plate to shield the alignment pattern 50 and the surrounding area, which simplifies the process flow, and the alignment pattern 50 of this structure is applicable to various types of batteries, and has strong versatility. In addition, since the first metal layer 33 of the conductive grid line 30 is not disconnected in the alignment pattern 50 area, it will not cause the problem of large contact resistance and poor conductivity in this area, thereby improving the quality of the photovoltaic module.

[0097] Optionally, depending on the type of battery, the conductive grid lines 30 may include a main grid and a fine grid, or the conductive grid lines 30 may include only a fine grid, i.e., a design without a main grid. The alignment pattern 50 may be provided in the region of the main grid, or in the region of the fine grid, or in the region of both the main grid and the fine grid.

[0098] When the top view shape of the groove 51 of the alignment pattern 50 is not limited, the top view shape of the groove 51 can be any one of a circle, a ring, an ellipse, a square, a rectangle, a cross, a polygon, and an irregular shape. Figure 1 For example, the top view shape of the groove 51 is a cross. When the alignment pattern 50 also includes a pattern portion 52, the top view shape or top surface 521 of the pattern portion 52 is not limited, and can be any of a circle, a ring, an ellipse, a square, a rectangle, a cross, a polygon, or an irregular shape. Figure 3 For example, the top view shape or the top surface 521 shape of the pattern portion 52 is a cross shape.

[0099] In some embodiments, in order to make the alignment process more accurate and efficient, the alignment pattern 50 includes a first alignment pattern 50a and a second alignment pattern 50b set on the target surface, and the first alignment pattern 50a and the second alignment pattern 50b can play an alignment role in different steps respectively.

[0100] In the third embodiment, the second alignment pattern 50b and the first alignment pattern 50a do not overlap each other. Figure 5As shown. For example, the second alignment pattern 50b can be set at a position adjacent to the first alignment pattern 50a. The structures of the first alignment pattern 50a and the second alignment pattern 50b are the same as the structure of the above-mentioned alignment pattern 50. For example, the first alignment pattern 50a and the second alignment pattern 50b can also only include a groove 51 that is recessed relative to the target surface, or both include a groove 51 that is recessed relative to the target surface and a pattern portion 52 located in the groove 51. In addition, a second metal layer 53 is also attached to the groove wall of the groove 51 of the first alignment pattern 50a and the second alignment pattern 50b. The second metal layer 53 is connected to the first metal layer 33 of the conductive gate line 30. The second metal layer 53 in the groove 51 of the first alignment pattern 50a and the second alignment pattern 50b has a height difference with the first metal layer 33 of the conductive gate line 30, and the two are integrally formed by a coating process. Figure 5 In the embodiment, the first alignment pattern 50a includes a groove 51 having a square shape in a top view and a pattern portion 52 having a cross shape in a top view; the groove 51 of the second alignment pattern 50b has a circular shape in a top view.

[0101] In the fourth embodiment, the second alignment pattern 50b at least partially overlaps with the first alignment pattern 50a. Figure 6 As shown. When the first alignment pattern 50a only includes the groove 51 and does not include the pattern portion 52, the second alignment pattern 50b is disposed in the groove 51 of the first alignment pattern 50a. The second alignment pattern 50b is convexly disposed on the bottom wall of the groove 51 and is spaced from the side wall of the groove 51. Although not shown, the second alignment pattern 50b includes a top surface facing away from the bottom wall of the groove 51 and a side surface connected to the top surface, wherein the side surface is connected between the bottom wall 511 and the top surface. In some embodiments, the top surface of the second alignment pattern 50b is flush with the target surface. Figure 6 In the figure, the top view shape of the groove 51 is a cross, and the top view shape (top surface shape) of the second alignment pattern 50b is a circle as an illustration.

[0102] The second alignment pattern 50b also has a metal layer on its top and side surfaces, and the metal layer on its surface is connected to the metal layer in the groove 51. The metal layer of the second alignment pattern 50b and the metal layer of the conductive gate line 30 are also integrally formed by the coating process.

[0103] Along the thickness direction of the battery substrate 10, the thickness of the metal layer of the second alignment pattern 50b is the same as the thickness of the metal layer of the conductive gate line 30, both of which are 0.5μm to 10μm. The height difference ΔH between the lowest point of the metal layer in the groove 51 of the first alignment pattern 50a and the highest point of the metal layer of the second alignment pattern 50b or the metal layer of the conductive gate line 30 is 0.5μm to 50μm.

[0104] like Figure 7As shown, in Example 5, the second alignment pattern 50b overlaps with the first alignment pattern 50a, the first alignment pattern 50a includes a groove 51 and a pattern portion 52 arranged in the groove 51, and the second alignment pattern 50b is arranged in the pattern portion 52 of the first alignment pattern 50a, and is a groove recessed relative to the top surface of the pattern portion 52. Figure 7 In the embodiment, the first alignment pattern 50a includes a groove 51 having a square shape in a top view and a pattern portion 52 having a cross shape in a top view; the groove of the second alignment pattern 50b has a circular shape in a top view.

[0105] It can be understood that, although not shown in the figure, a metal layer is formed on the groove wall of the groove 51 of the first alignment pattern 50a and the surface of the pattern portion 52, and a metal layer is also formed on the groove wall of the groove of the second alignment pattern 50b, and the metal layer of the first alignment pattern 50a is connected to the metal layer of the second alignment pattern 50b and to the metal layer of the conductive gate line 30.

[0106] The first metal layer 33 of the conductive grid line 30 and the second metal layer 53 in the groove 51 and on the pattern portion 52 may include a first sub-metal layer and a second sub-metal layer stacked in sequence on the surface of the battery substrate 10, wherein the first sub-metal layer is located between the battery substrate 10 and the second sub-metal layer. The standard electrode potential difference between the first sub-metal layer and the second sub-metal layer is 0.1 to 3.5V.

[0107] It can be understood that the first sub-metal layer is not in direct contact with the battery substrate 10. For example, for a battery with a Topcon structure, a passivation layer or a passivation anti-reflection layer (for example, a silicon nitride layer and an aluminum oxide layer), a doped polysilicon layer and a tunneling oxide layer are further provided between the first sub-metal layer and the battery substrate 10, and the tunneling oxide layer is in contact with the battery substrate 10; or, a doped polysilicon layer and a tunneling oxide layer are further provided between the first sub-metal layer and the battery substrate 10, and the tunneling oxide layer is in contact with the battery substrate 10; or, a TCO layer, a doped polysilicon layer and a tunneling oxide layer are further provided between the first sub-metal layer and the battery substrate 10, and the tunneling oxide layer is in contact with the battery substrate 10. For example, for a battery with an HJT structure, a TCO layer, a doped amorphous silicon layer and an intrinsic amorphous silicon layer are further provided between the first sub-metal layer and the battery substrate 10, and the intrinsic amorphous silicon layer is in contact with the battery substrate 10.

[0108] In some embodiments, the material of the first sub-metal layer includes one or more of Al, Zn, Fe, Co, Mg, Cu, Ag and alloys thereof. The material of the second sub-metal layer includes one or more of Cu, Ni, Cr, Ti, W, Mo, Ag, Sn and alloys thereof.

[0109] In some embodiments, the thickness of the second sub-metal layer is less than or equal to 10% of the thickness of the first sub-metal layer. The second sub-metal layer is disposed on the first sub-metal layer to protect the first sub-metal layer, and the second sub-metal layer needs to be connected to other layers of the battery (such as the packaging layer) later, which can improve the bonding strength between the metal layer and the other layers (such as the packaging layer). Therefore, the thickness of the second sub-metal layer does not need to be set too thick, and can be less than or equal to 10% of the thickness of the first sub-metal layer.

[0110] In some embodiments, the first sub-metal layer is composed of two or more sub-layers, and the material of each sub-layer is selected from one or more of Al, Zn, Fe, Co, Mg, Cu, Ag and alloys thereof.

[0111] In some embodiments, the conductive grid line 30, the groove 51 and the pattern part 52 further include a buffer layer disposed between the first sub-metal layer and the battery substrate 10. The buffer layer includes one or more combinations of metal oxides, metal nitrides, metal fluorides, metal silicides and metals. The buffer layer serves to enhance the bonding strength between the first metal layer 33 / the second metal layer 53 and the battery substrate 10.

[0112] In some embodiments, the metal oxide includes AZO, TiO x 、Cu2O、MgO x 、TaO x , VO x CrO x 、SnO2、B:ZnO、CdO x and MoO x In some embodiments, the metal nitride includes TiN x and TiO x N y In some embodiments, the metal fluoride comprises one or more combinations of MgF2, LiF, YF3 and CeF3. In some embodiments, the metal silicide comprises one or more combinations of TiSi2, TaSi2, MOSi2, CoSi2, Ni2Si and WSi2. In some embodiments, the metal comprises one or more combinations of Ni, Ti, Cr, Cu, W, Mo and Ag.

[0113] The thickness of the buffer layer is less than or equal to 10% of the thickness of the first sub-metal layer, and the projection width of the buffer layer on the battery substrate 10 is less than or equal to the width of the corresponding doping region.

[0114] In one embodiment, the thickness of the buffer layer is 5 nm to 300 nm, the thickness of the first sub-metal layer is 0.5 μm to 20 μm, and the thickness of the second sub-metal layer is 5 nm to 300 nm.

[0115] The present application also provides a method for preparing the above-mentioned solar cell, which comprises the following steps S1 to S3.

[0116] S1: Provide a battery substrate 10, which includes a first surface 11 and a second surface 12 relative to each other, wherein at least one of the first surface 11 and the second surface 12 is a target surface.

[0117] S2: forming a groove 51 of the alignment pattern 50 on the target surface.

[0118] In some embodiments, when the groove 51 is formed, a part of the battery substrate 10 is retained in the space surrounded by the groove 51 to form a pattern portion 52 protruding from the bottom of the groove 51 .

[0119] The groove 51 can be formed by laser processing, photolithography processing, physical grinding, wet etching, dry etching, etc.

[0120] S3: forming the first metal layer 33 of the conductive gate line 30 on the target surface and forming the second metal layer 53 on the groove wall of the groove 51 at the same time, and the first metal layer 33 of the conductive gate line 30 is connected to the second metal layer 53 in the groove 51.

[0121] The first metal layer 33 and the second metal layer 53 may be formed by physical vapor deposition (eg, evaporation, magnetron sputtering), chemical vapor deposition, electroplating, screen printing, and the like.

[0122] In some embodiments, the second metal layer 53 in the groove 51 has the same thickness as the first metal layer 33 of the conductive gate line 30 .

[0123] In some embodiments, the thickness of the second metal layer 53 in the groove 51 and the first metal layer 33 of the conductive gate line 30 are both in the range of 0.5 μm to 10 μm.

[0124] In some embodiments, along the thickness direction of the battery substrate 10 , a height difference ΔH between the first metal layer 33 of the conductive grid line 30 and the lowest point of the second metal layer 53 in the groove 51 is 0.5 μm to 50 μm.

[0125] In some embodiments, forming the first metal layer and the second metal layer includes first forming a first sub-metal layer and then forming a second sub-metal layer stacked with the first sub-metal layer. The standard electrode potential difference between the first sub-metal layer and the second sub-metal layer is 0.1-3.5V.

[0126] In some embodiments, the material of the first sub-metal layer includes one or more of Al, Zn, Fe, Co, Mg, Cu, Ag and alloys thereof. The material of the second sub-metal layer includes one or more of Cu, Ni, Cr, Ti, W, Mo, Ag, Sn and alloys thereof.

[0127] In some embodiments, the thickness of the second sub-metal layer is less than or equal to 10% of the thickness of the first sub-metal layer.

[0128] When the pattern portion 52 is formed in the groove 51 , step S3 further includes forming a second metal layer 53 on the outer surface of the pattern portion 52 while forming the first metal layer 33 of the conductive gate line 30 .

[0129] The present application also provides a photovoltaic module comprising the above solar cell.

[0130] In some embodiments, the photovoltaic module includes a glass cover plate, a film layer, a battery layer, a film layer and a transparent or opaque back plate stacked in sequence, wherein when the back plate is transparent, a glass cover plate can be selected for the back plate. The battery layer includes a plurality of the above-mentioned solar cells connected in series. The number of solar cells connected in series can be, for example, 4 to 20. These solar cells form a plurality of battery modules, each of which has the same number of solar cells. The solar cells in the battery modules are connected in series, and the battery modules can be connected in series or in parallel. The spacing between two adjacent battery modules is 0.5 to 10 mm, and the spacing between two adjacent battery cells in each battery module is 0.5 to 10 mm.

[0131] The solar cell provided in the application does not need to prepare the metal layer of the conductive grid line 30 and the alignment pattern 50 by screen printing conductive paste, so there is no need to specially design a screen printing screen to shield the alignment pattern 50 and the surrounding area, which simplifies the process flow, and such an alignment pattern 50 structure is applicable to various types of batteries and has strong versatility. In addition, since the first metal layer 33 of the conductive grid line 30 is not disconnected in the area of ​​the alignment pattern 50, it will not affect the collection and transmission of carriers in the area of ​​the alignment pattern 50, nor will it cause the problem of large contact resistance and poor conductivity in the area of ​​the alignment pattern 50, thereby improving the quality of the photovoltaic module. There is a height difference between the second metal layer 53 in the groove 51 of the alignment pattern 50 and the first metal layer 33 of the conductive grid line 30. Due to light reasons, there is a large color difference and a strong contrast between the alignment pattern 50 and the surrounding area, so that the alignment pattern 50 can be clearly captured by the camera and will not affect the alignment of the solar cell.

[0132] The above implementation modes are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the above preferred implementation modes, a person skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A solar cell, characterized in that: include: a battery substrate, the battery substrate comprising a first surface and a second surface opposite to each other, wherein at least one of the first surface and the second surface is a target surface; A conductive grid line, located on the target surface and comprising a first metal layer disposed on the target surface; An alignment pattern, arranged on the target surface and located in the area where the conductive gate line is located, the alignment pattern comprising a second metal layer; The second metal layer is connected to the first metal layer, and the first metal layer and the second metal layer are used to transmit carriers with the same polarity.

2. The solar cell according to claim 1, characterized in that The alignment pattern comprises a groove that is concave relative to the target surface, the groove wall comprises a bottom wall and a side wall surrounding and connecting the bottom wall, and the second metal layer is attached to the bottom wall and the side wall; Along the thickness direction of the battery substrate, the second metal layer has a height difference with the first metal layer.

3. The solar cell according to claim 2, characterized in that: Along the thickness direction of the battery substrate, the second metal layer on the bottom wall has the same thickness as the first metal layer; and / or, The thickness of the second metal layer and the first metal layer are both in the range of 0.5 μm to 10 μm; and / or, Along the thickness direction of the battery substrate, the height difference ΔH between the first metal layer and the second metal layer on the bottom wall is 0.5 μm to 50 μm, wherein ΔH is the height difference between the highest point of the first metal layer and the lowest point of the second metal layer on the bottom wall along the thickness direction of the battery substrate; and / or, A carrier transport layer is also arranged between the bottom wall and the second metal layer on the bottom wall.

4. The solar cell according to claim 2, characterized in that: The alignment pattern further includes a pattern portion disposed in the groove, the pattern portion being convexly disposed on the bottom wall and spaced apart from the side wall; The pattern portion includes a top surface facing away from the bottom wall and a side surface connected to the top surface, wherein the side surface is connected between the bottom wall and the top surface.

5. The solar cell according to claim 4, characterized in that: The second metal layer is also disposed on the top surface and the side surface; Along the thickness direction of the battery substrate, the second metal layer on the top surface has a flush surface with the first metal layer; and / or, Along the thickness direction of the battery substrate, the second metal layer on the top surface has the same thickness as the first metal layer; and / or, The thickness of the second metal layer and the first metal layer on the pattern portion are both in the range of 0.5 μm to 10 μm; and / or, Along the thickness direction of the battery substrate, the height difference ΔH between the second metal layer on the top surface and the second metal layer on the bottom wall is 0.5 μm to 50 μm, wherein ΔH is the height difference between the highest point of the second metal layer on the top surface and the lowest point of the second metal layer on the bottom wall along the thickness direction of the battery substrate; and / or, A carrier transport layer is further provided between the top surface and the second metal layer on the top surface; and / or, A groove recessed relative to the top surface is formed in the pattern portion, and a metal layer connected to the second metal layer is formed on the groove wall.

6. The solar cell according to claim 1, characterized in that The second metal layer and the first metal layer both include a first sub-metal layer and a second sub-metal layer stacked in layers, wherein the first sub-metal layer is located between the battery substrate and the second sub-metal layer; The standard electrode potential difference between the first sub-metal layer and the second sub-metal layer is 0.1 to 3.5 V; and / or, The material of the first sub-metal layer includes one or more of Al, Zn, Fe, Co, Mg, Cu, Ag and alloys thereof; and / or, The material of the second sub-metal layer includes one or more of Cu, Ni, Cr, Ti, W, Mo, Ag, Sn and alloys thereof; and / or, The thickness of the second sub-metal layer is less than or equal to 10% of the thickness of the first sub-metal layer; and / or, The first sub-metal layer is composed of two or more sub-layers, and the material of each sub-layer is selected from one or more of Al, Zn, Fe, Co, Mg, Cu, Ag and alloys thereof.

7. The solar cell according to claim 6, characterized in that: A buffer layer is further provided between the first sub-metal layer and the battery substrate, wherein the buffer layer comprises one or more combinations of metal oxides, metal nitrides, metal fluorides, metal silicides and metals; The metal oxides include AZO, TiO x 、Cu2O、MgO x 、TaO x , VO x CrO x 、SnO2、B:ZnO、CdO x and MoO x One or more combinations of; and / or, The metal nitride includes TiN x and TiO x N y One or more combinations of; and / or, The metal fluoride comprises one or more combinations of MgF2, LiF, YF3 and CeF3; and / or, The metal silicide comprises one or more combinations of TiSi2, TaSi2, MOSi2, CoSi2, Ni2Si and WSi2; and / or, The metal includes one or more combinations of Ni, Ti, Cr, Cu, W, Mo and Ag.

8. A method for preparing a solar cell, characterized in that: include: providing a battery substrate, the battery substrate comprising a first surface and a second surface opposite to each other, wherein at least one of the first surface and the second surface is a target surface; forming a groove of an alignment pattern on the target surface; A first metal layer of conductive grid lines is formed on the target surface and a second metal layer is formed on the groove wall of the groove, the first metal layer is connected to the second metal layer, and along the thickness direction of the battery substrate, the first metal layer and the second metal layer have a height difference.

9. The method for preparing a solar cell according to claim 8, characterized in that: The groove wall of the groove includes a bottom wall and a side wall surrounding and connecting the bottom wall. When the groove is formed, a part of the battery substrate is retained in the space surrounded by the groove to form a pattern portion protruding on the bottom wall; and / or, The second metal layer on the bottom wall has the same thickness as the first metal layer; and / or, The thickness of the second metal layer and the first metal layer are both in the range of 0.5 μm to 10 μm; and / or, Along the thickness direction of the battery substrate, the height difference ΔH between the first metal layer and the second metal layer on the bottom wall is 0.5μm to 50μm, where ΔH is the height difference between the highest point of the first metal layer and the lowest point of the second metal layer on the bottom wall along the thickness direction of the battery substrate.

10. A photovoltaic module, comprising a glass cover plate, a film layer, a battery layer, a film layer and a transparent or opaque back plate stacked in sequence, characterized in that: The cell layer includes a plurality of solar cells according to any one of claims 1 to 7 or solar cells prepared by the preparation method according to claim 8 or 9 connected in series.

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