A method for manufacturing a solar cell and a solar cell

Abstract

The application provides a preparation method of a solar cell and the solar cell, and relates to the technical field of solar cells. The method comprises the following steps: arranging a mask layer on a first surface of a cell base; opening a groove in the mask layer, so that a region to be provided with a metal electrode on the first surface of the cell base is exposed; depositing a metal layer on the remaining mask layer and the region to be provided with the metal electrode on the first surface of the cell base; taking the region to be provided with the metal electrode on the first surface of the cell base and the metal layer on the remaining mask layer as a cathode and an anode respectively, and performing electroplating, so that the metal in the metal layer on the remaining mask layer is electroplated to the region to be provided with the metal electrode on the first surface of the cell base. The distance between the anode and the cathode is greatly reduced, the difficulty and cost of electroplating are reduced, and the replenishment speed of metal ions and the production speed of the metal electrode electroplating are improved.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a method for preparing a solar cell and the solar cell itself. Background Technology

[0002] Currently, electroplating can be used to set metal electrodes for solar cells. During electroplating, the area of ​​the solar cell where the metal electrode will be placed is used as the cathode, and the metal material is used as the anode. The anode and cathode are placed in an electroplating solution. Under the influence of an electric field, metal ions move through the electroplating solution to the area of ​​the solar cell where the metal electrode needs to be placed, thus forming the metal electrode of the solar cell.

[0003] In existing electroplating methods, the distance between the cathode and anode ranges from 1 to 100 mm. However, as the distance between the cathode and anode increases, the difficulty of electroplating increases exponentially, and the cost of electroplating rises significantly. Summary of the Invention

[0004] This invention provides a method for preparing a solar cell and a solar cell, aiming to solve the problems of high difficulty and high cost in the process of electroplating metal electrodes.

[0005] A first aspect of the present invention provides a method for preparing a solar cell, the method comprising: A mask layer is disposed on a first surface of a battery substrate; the battery substrate includes a silicon substrate; the first surface of the battery substrate is the surface on which a metal electrode is to be disposed; A groove is formed in the mask layer so that the area on the first surface of the battery substrate to be provided with metal electrodes is exposed. A metal layer is deposited on the remaining mask layer and on the area on the first surface of the battery substrate where the metal electrode is to be disposed; The areas on the first surface of the battery substrate where metal electrodes are to be disposed, which are all located on the same side of the silicon substrate, and the remaining metal layer on the mask layer are used as the cathode and anode, respectively, and electroplating is performed so that the metal in the remaining metal layer on the mask layer is electroplated onto the areas on the first surface of the battery substrate where metal electrodes are to be disposed, thereby forming the metal electrodes of the battery substrate.

[0006] In this embodiment of the invention, the area on the first surface of the battery substrate where the metal electrode is to be disposed, and the metal layer on the remaining mask layer, located on the same side of the silicon substrate, are used as the cathode and anode, respectively, for electroplating. During the electroplating process, the entire battery substrate is placed in the electroplating solution. The electroplating device does not require an anode. Through the distribution of the transverse electric field, metal ions move laterally from the metal layer on the remaining mask layer to the area on the first surface of the battery substrate where the metal electrode is to be disposed, thereby forming the metal electrode of the battery substrate. The area on the first surface of the battery substrate where the metal electrode is to be disposed, which serves as the cathode, and the metal layer on the remaining mask layer, which serves as the anode, are located on the same side of the silicon substrate. During the electroplating process to form the metal electrode, the distance between the anode and the cathode is the distance between the area on the first surface of the battery substrate where the metal electrode is to be disposed and the metal layer on the remaining mask layer, both located on the same side of the silicon substrate. In this embodiment of the invention, the distance between the anode and the cathode is only at the micrometer level. This significantly reduces the distance between the anode and the cathode, which not only reduces the difficulty and cost of electroplating but also enables the nearby replenishment of metal ions, increases the replenishment speed of metal ions, and accelerates the mass production of metal electrode electroplating.

[0007] Optionally, the opening of the tank is located at the end of the tank away from the silicon substrate, and the bottom of the tank is distributed opposite to the opening of the tank; when the battery substrate is an HJT battery substrate or an HBC battery substrate: After the metal layers are deposited, they are all located on the same side of the silicon substrate. The metal layer on the bottom of the trench is farther away from the surface of the silicon substrate and closer to the surface of the mask layer than the metal layer on the remaining mask layer, and closer to the silicon substrate. Electroplating includes: using a metal layer located on the same side of the silicon substrate, on the bottom of the tank and the remaining metal layer on the mask layer as the cathode and anode, respectively, for electroplating.

[0008] Optionally, the tank wall is located between the opening of the tank and the bottom of the tank; when the surface of the mask layer away from the silicon substrate blocks the tank wall, during the deposition of the metal layer: both are located on the same side of the silicon substrate, and the metal layer on the bottom of the tank and the remaining metal layer on the mask layer are naturally separated. In other cases, prior to electroplating, the method further includes removing metal layers from the tank walls such that they are all located on the same side of the silicon substrate, and the metal layers on the tank bottom are disconnected from the remaining metal layers on the mask layer.

[0009] Optionally, if the battery substrate is an HJT battery substrate: The method of setting a mask layer includes: setting a front mask layer on the light-facing surface of the battery substrate, and / or setting a back mask layer on the back-facing surface of the battery substrate; The process of creating a groove includes: creating a groove in the front mask layer, and / or creating a groove in the back mask layer; The deposition of a metal layer includes: depositing a front metal layer on the remaining front mask layer and on the bottom of a trench on the light-facing side of the battery substrate; and / or depositing a back metal layer on the remaining back mask layer and on the bottom of a trench on the back side of the battery substrate. Electroplating includes: electroplating a metal layer on the bottom of the tank on the light-facing side of the silicon substrate and a metal layer on the remaining front mask layer, respectively, as the cathode and anode; and / or electroplating a metal layer on the bottom of the tank on the back-facing side of the silicon substrate and a metal layer on the remaining back mask layer, respectively, as the cathode and anode.

[0010] Optionally, when the battery substrate is an HBC battery substrate: The method of setting a mask layer includes: setting a back mask layer on the back surface of the battery substrate; Creating a groove includes: creating a groove in the back mask layer; Depositing a metal layer includes: depositing a back metal layer on the remaining back mask layer and on the bottom of the trench on the back surface of the battery substrate; Electroplating includes: using the metal layer on the bottom of the tank on the backlight side of the silicon substrate and the remaining metal layer on the back mask layer as the cathode and anode, respectively, for electroplating.

[0011] Optionally, the opening of the tank is located at the end of the tank away from the silicon substrate, the bottom of the tank is opposite to the opening of the tank, and the tank wall is located between the opening of the tank and the bottom of the tank; when the battery substrate is a TOPCon battery substrate, the battery substrate includes a silicon nitride layer: The deposition of a metal layer includes: sequentially depositing an electrode metal layer and a contact barrier metal layer on the remaining mask layer and on the area on the first surface of the battery substrate where a metal electrode is to be disposed; When the surface of the mask layer away from the silicon substrate obstructs the trench wall, during the deposition of the electrode metal layer and the contact barrier metal layer: both are located on the same side of the silicon substrate, and the electrode metal layer on the bottom of the trench and the remaining electrode metal layer on the mask layer are naturally disconnected; and both are located on the same side of the silicon substrate, and the contact barrier metal layer on the bottom of the trench and the remaining contact barrier metal layer on the mask layer are naturally disconnected; after the electrode metal layer and the contact barrier metal layer are deposited sequentially, the method further includes: during the trenching process in the silicon nitride layer, removing both the electrode metal layer and the contact barrier metal layer on the bottom of the trench; In other cases, after sequentially depositing the electrode metal layer and the contact barrier metal layer, the method further includes: during the process of trenching in the silicon nitride layer, removing the electrode metal layer and the contact barrier metal layer on the trench wall, as well as the electrode metal layer and the contact barrier metal layer on the trench bottom. Electroplating includes: performing a first electroplating on the same side of the silicon substrate, where the electrode metal layer and contact barrier metal layer have been removed from the bottom of the tank, and the remaining contact barrier metal layer on the mask layer, respectively serving as the cathode and anode; and performing a second electroplating on the same side of the silicon substrate, where the contact barrier metal layer has been electroplated on the bottom of the tank, and the remaining electrode metal layer on the mask layer, respectively serving as the cathode and anode.

[0012] Optionally, the mask layer is provided, including: providing a front mask layer on the light-facing surface of the battery substrate, and / or providing a back mask layer on the back-facing surface of the battery substrate; The process of creating a groove includes: creating a groove in the front mask layer, and / or creating a groove in the back mask layer; Sequentially depositing an electrode metal layer and a contact barrier metal layer, including: On the remaining front mask layer and on the bottom of the trench on the light-facing side of the battery substrate, a front electrode metal layer and a front contact barrier metal layer are sequentially deposited; and / or, on the remaining back mask layer and on the bottom of the trench on the back side of the battery substrate, a back electrode metal layer and a back contact barrier metal layer are sequentially deposited. The silicon nitride layer includes a front silicon nitride layer and a back silicon nitride layer; the process of removing the electrode metal layer and contact barrier metal layer on the bottom of the trench during the trenching process in the silicon nitride layer includes: when the surface of the front mask layer away from the silicon substrate blocks the trench wall on the light-facing side of the silicon substrate, removing the front electrode metal layer and the front contact barrier metal layer on the bottom of the trench on the light-facing side of the silicon substrate during the trenching process in the front silicon nitride layer; and / or, when the surface of the back mask layer away from the silicon substrate blocks the trench wall on the back light-facing side of the silicon substrate, removing the back electrode metal layer and the back contact barrier metal layer on the bottom of the trench on the back light-facing side of the silicon substrate during the trenching process in the back silicon nitride layer. The process of creating a groove in the silicon nitride layer, removing the electrode metal layer and contact barrier metal layer on the groove wall, and the electrode metal layer and contact barrier metal layer on the groove bottom, includes: removing the front electrode metal layer and front contact barrier metal layer on the groove wall on the light-facing side of the silicon substrate, and the front electrode metal layer and front contact barrier metal layer on the groove bottom on the light-facing side of the silicon substrate during the process of creating a groove in the front silicon nitride layer; and / or, removing the back electrode metal layer and back contact barrier metal layer on the groove wall on the backlight side of the silicon substrate, and the back electrode metal layer and back contact barrier metal layer on the groove bottom on the backlight side of the silicon substrate during the process of creating a groove in the back silicon nitride layer; The first electroplating includes: removing the front electrode metal layer and the front contact barrier metal layer from the bottom of the tank on the light-facing side of the silicon substrate, and using the remaining front contact barrier metal layer on the front mask layer as the cathode and anode, respectively, for the first electroplating; and / or, removing the back electrode metal layer and the back contact barrier metal layer from the bottom of the tank on the back-facing side of the silicon substrate, and using the remaining back contact barrier metal layer on the back mask layer as the cathode and anode, respectively, for the first electroplating; The second electroplating includes: using the area on the bottom of the tank on the light-facing side of the silicon substrate where the front contact barrier metal has been plated and the remaining front electrode metal layer on the front mask layer as the cathode and anode, respectively, for a second electroplating; and / or using the area on the bottom of the tank on the back-facing side of the silicon substrate where the back contact barrier metal has been plated and the remaining back electrode metal layer on the back mask layer as the cathode and anode, respectively, for a second electroplating.

[0013] Optionally, after forming the metal electrodes of the battery substrate: If there is residual metal on the remaining mask layer, the method further includes: removing the residual metal from the remaining mask layer; If the mask layer is a non-anti-reflective film layer, the method further includes: removing the remaining mask layer.

[0014] Optionally, the material of the mask layer is selected from one of the following: photoresist, ink, paraffin, organic thin film, dielectric material, and metal oxide; And / or, the thickness of the mask layer is 1-50 μm; the thickness of the mask layer is: the dimension of the mask layer in the direction in which the mask layer is disposed on the battery substrate; And / or, the mask layer includes at least one of spin coating, roller coating, spray coating, and dip coating; And / or, the groove includes at least one of: exposure development, mechanical scribing, and laser scribing; And / or, the deposited metal layer includes at least one of: vapor deposition, sputtering, and electroplating; And / or, the material of the metal layer is selected from at least one of nickel, copper, silver, and tin; And / or, the thickness of the metal layer is 100-300 nm; When the material of the metal layer is selected from copper, the electroplating solution includes copper sulfate solution and electroplating additives during the electroplating process.

[0015] Optionally, when the surface of the mask layer away from the silicon substrate obstructs the trench wall, the shape of the trench includes at least one of the following: a frustum, a truncated cone, and a bowl-shaped structure.

[0016] Optionally, if the material of the mask layer is photoresist, removing the remaining residual metal on the remaining mask layer includes: using a first alkaline solution to remove the remaining residual metal on the remaining mask layer; When the material of the mask layer is photoresist, removing the remaining mask layer includes: removing the remaining mask layer using a second alkaline solution.

[0017] Optionally, the first alkaline solution is obtained by mixing ammonia water with a concentration of 1.8-2.4 mol / L and hydrogen peroxide with a concentration of 0.55-0.66 mol / L; The second alkaline solution comprises: a 0.1-0.3 mol / L sodium hydroxide solution.

[0018] Optionally, if the mask layer is made of photoresist, the grooves are formed, including: laser grooving with a laser wavelength of 350nm-460nm and a laser energy of 50-70mJ / cm. 2 .

[0019] Optionally, the material of the contact barrier metal layer includes nickel, and / or the material of the electrode metal layer includes copper.

[0020] A second aspect of the present invention provides a solar cell, which is prepared by any of the aforementioned methods for preparing a solar cell. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A flowchart illustrating the steps of a method for preparing a solar cell according to an embodiment of the present invention is shown; Figure 2 A partial structural schematic diagram of a first type of solar cell in an embodiment of the present invention is shown; Figure 3 A partial structural schematic diagram of a second type of solar cell in an embodiment of the present invention is shown; Figure 4 A partial structural schematic diagram of a third type of solar cell in an embodiment of the present invention is shown; Figure 5 A partial structural schematic diagram of the fourth type of solar cell in an embodiment of the present invention is shown; Figure 6 A schematic diagram of the electroplating principle in an embodiment of the present invention is shown; Figure 7 A partial structural schematic diagram of the fifth type of solar cell in an embodiment of the present invention is shown; Figure 8 A partial structural schematic diagram of the sixth type of solar cell in an embodiment of the present invention is shown; Figure 9 A schematic diagram of the structure of an HJT battery substrate according to an embodiment of the present invention is shown; Figure 10 A partial structural schematic diagram of the first type of HJT solar cell in an embodiment of the present invention is shown; Figure 11 A partial structural schematic diagram of the second type of HJT solar cell in an embodiment of the present invention is shown; Figure 12 A partial structural schematic diagram of the third type of HJT solar cell in an embodiment of the present invention is shown; Figure 13A partial structural schematic diagram of the fourth HJT solar cell in an embodiment of the present invention is shown; Figure 14 A partial structural schematic diagram of the fifth type of HJT solar cell in an embodiment of the present invention is shown; Figure 15 A schematic diagram of the structure of an HJT solar cell according to an embodiment of the present invention is shown; Figure 16 A schematic diagram of the structure of an HBC battery substrate according to an embodiment of the present invention is shown; Figure 17 A partial structural schematic diagram of the first type of HBC solar cell in an embodiment of the present invention is shown; Figure 18 A partial structural schematic diagram of the second type of HBC solar cell in an embodiment of the present invention is shown; Figure 19 A partial structural schematic diagram of the third type of HBC solar cell in an embodiment of the present invention is shown; Figure 20 A partial structural schematic diagram of the fourth HBC solar cell in an embodiment of the present invention is shown; Figure 21 A partial structural schematic diagram of the fifth type of HBC solar cell in an embodiment of the present invention is shown; Figure 22 A schematic diagram of the structure of an HBC solar cell according to an embodiment of the present invention is shown; Figure 23 A schematic diagram of the structure of a TOPCon battery substrate according to an embodiment of the present invention is shown; Figure 24 A partial structural schematic diagram of the first type of TOPCon solar cell in an embodiment of the present invention is shown; Figure 25 A partial structural schematic diagram of the second type of TOPCon solar cell in an embodiment of the present invention is shown; Figure 26 A partial structural schematic diagram of the third type of TOPCon solar cell in an embodiment of the present invention is shown; Figure 27 A partial structural schematic diagram of the fourth TOPCon solar cell in an embodiment of the present invention is shown; Figure 28 A partial structural schematic diagram of the fifth type of TOPCon solar cell in an embodiment of the present invention is shown; Figure 29 A partial structural schematic diagram of the sixth type of TOPCon solar cell in an embodiment of the present invention is shown; Figure 30A schematic diagram of the structure of a TOPCon solar cell according to an embodiment of the present invention is shown.

[0023] Explanation of the attached drawing numbers: 1-Battery substrate, 2-Mask layer, 3-Metal layer, 4-Metal electrode, 21-Front-side mask layer, 22-Back-side mask layer, 23-Gate, 101-Front-side TCO film, 102-N-type hydrogen-doped amorphous silicon / microcrystalline silicon oxide passivation layer, 103-Front-side intrinsic amorphous silicon passivation layer, 104-Front-side intrinsic amorphous silicon buffer layer, 105-Silicon substrate, 106-Back-side intrinsic amorphous silicon buffer layer, 107-Back-side intrinsic amorphous silicon passivation layer, 108-P-type amorphous silicon emitter, 109-Back-side TCO film, 110-Front-side silicon nitride layer, 111-Front-side n-layer, 112-Front-side i-layer, 113-Back-side i-layer, 114-n-type layer, 115-p-type layer, 116-Separator layer, 117-Alumina thin film, 118 - Boron-doped emitter, 119- Back ultrathin oxide film, 120- Phosphorus-doped polycrystalline silicon film, 121- Back silicon nitride layer, 31- Front metal layer, 32- Back metal layer, 33- Metal layer on the trench wall, 311- Metal layer on the remaining front mask layer, 312- Metal layer on the bottom of the trench on the light-facing side of the silicon substrate, 321- Metal layer on the remaining back mask layer, 322- Metal layer on the bottom of the trench on the back side of the battery substrate, 3111- Front electrode metal layer, 3112- Front contact barrier metal layer, 3211- Back electrode metal layer, 3212- Back contact barrier metal layer, 41- Front metal electrode, 42- Back metal electrode, 51- Front contact barrier metal, 52- Back contact barrier metal. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Figure 1 A flowchart illustrating the steps of a method for fabricating a solar cell according to an embodiment of the present invention is shown. Figure 2 A partial structural schematic diagram of a first type of solar cell according to an embodiment of the present invention is shown. (Refer to...) Figure 1 , Figure 2 As shown, the method includes the following steps: Step S1: A mask layer is formed on the first surface of the battery substrate; the battery substrate includes a silicon substrate; the first surface of the battery substrate is the surface on which the metal electrode is to be formed.

[0026] The main function of the battery substrate 1 is to separate and transport charge carriers. The specific composition of the battery substrate 1 is not specifically limited; it can be any part of a solar cell excluding the metal electrodes. The main function of the metal electrodes is to extract charge carriers; the metal electrodes can be the front metal electrodes and / or the back metal electrodes of the battery substrate, but this is not specifically limited in this embodiment of the invention.

[0027] The battery substrate 1 includes a silicon substrate, and the type of silicon substrate is not specifically limited. The doping type of the silicon substrate can be N-type or P-type. The battery substrate 1 can be any battery substrate suitable for electroplating metal electrodes. For example, the battery substrate 1 can be a crystalline silicon battery substrate, a thin-film battery substrate, a thin-film / crystalline silicon tandem battery substrate, etc. In this embodiment of the invention, no specific limitation is made.

[0028] The first surface of the battery substrate 1 is the surface on which the metal electrode is to be disposed. For example, if the battery substrate 1 is a back-contact solar cell, then the first surface of the battery substrate 1 is the backlight surface of the battery substrate 1. A mask layer 2 is disposed on the first surface of the battery substrate 1, specifically, the mask layer 2 can be disposed on the entire first surface of the battery substrate 1. The disposal method is not specifically limited. The material of the mask layer 2 is also not specifically limited.

[0029] Optionally, the material of the mask layer 2 is selected from one of the following: photoresist, ink, paraffin wax, organic thin film, dielectric material, and metal oxide. Mask layers 2 made of the above materials are easy to prepare and have good masking effect. The dielectric material can be silicon dioxide, silicon nitride, etc. The metal oxide can be aluminum oxide, titanium oxide, etc.

[0030] Reference Figure 2 As shown, optionally, the thickness h1 of the mask layer 2 can be 1-50 μm (micrometers). Mask layers 2 with a thickness range of the upper range not only have lower cost but also better masking effect. The thickness h1 of the mask layer 2 is the dimension of the mask layer 2 in the setting direction between the battery substrate 1 and the mask layer 2.

[0031] Optionally, the mask layer can be applied by coating; more specifically, the mask layer can be applied by at least one of spin coating, roller coating, spray coating, and dip coating. The above methods of applying the mask layer are simple in process.

[0032] Step S2: A groove is formed in the mask layer so that the area on the first surface of the battery substrate to be provided with metal electrodes is exposed.

[0033] Figure 3 A partial structural schematic diagram of a second type of solar cell according to an embodiment of the present invention is shown. (Refer to...) Figure 3 As shown, a groove 23 is formed in the mask layer 2, so that the area on the first surface of the battery substrate 1 where the metal electrode is to be placed is exposed.

[0034] During the process of creating the groove, grid lines can also be formed, and the specific shape of the grid lines is not specifically limited.

[0035] Optionally, the method of creating the groove includes at least one of exposure and development, mechanical scribing, and laser scribing. The above methods of creating the groove are simple in process. For example, the material of the mask layer 2 can be photoresist, and the groove can be created by exposure and development.

[0036] Optionally, when the material of mask layer 2 is photoresist, the method of creating the groove includes: laser grooving, with a laser wavelength of 350nm-460nm, an exposure time of 1-3min, or even less than or equal to 10s, and a laser energy of 50-70mJ / cm². 2 The above-mentioned grooving method is simple in process. For example, the laser wavelength is 405nm, the exposure time is 2min, and the laser energy is 60mJ / cm². 2 .

[0037] After grooving, the battery substrate can be cleaned, dried, and cooled. For example, if the material of mask layer 2 is photoresist, the photoresist that has undergone photochemical reaction can be removed by spraying with a 1% NaHCO3 solution, and the battery substrate after grooving can be cleaned by spraying with deionized water. Drying is done with hot air at 50℃ and cooling with cold air at 25℃.

[0038] Step S3: Deposit a metal layer on the remaining mask layer and on the area on the first surface of the battery substrate where the metal electrode is to be disposed.

[0039] Figure 4 A partial structural schematic diagram of a third type of solar cell according to an embodiment of the present invention is shown. (Refer to...) Figure 4 As shown, a metal layer 3 is deposited on the remaining mask layer 2 after trenching and on the area on the first surface of the battery substrate 1 where metal electrodes are to be disposed. The area on the first surface of the battery substrate 1 where metal electrodes are to be disposed is the bottom of the trench, and the opening of the trench is located at the end of the trench away from the silicon substrate. The bottom and opening of the trench are relatively distributed. This step is to deposit a metal layer 3 on the remaining mask layer 2 after trenching and on the bottom of the trench.

[0040] Optionally, the deposited metal layer may include at least one of the following: vapor deposition, sputtering, and electroplating, which are simple processes.

[0041] Optional, refer to Figure 4As shown, the thickness h2 of the metal layer 3 is 100-300 nm. After electroplating, the remaining thickness of the metal layer 3 on the remaining mask layer 2 is small or almost non-existent, which helps to save costs. For example, the thickness h2 of the metal layer 3 is 200 nm.

[0042] Optionally, the material of the metal layer 3 is selected from at least one of nickel, copper, silver, and tin, and the electroplating of the metal layer with the above materials is simple.

[0043] Optionally, when the metal layer material is selected from copper, the electroplating solution includes: copper sulfate solution and electroplating additives. The specific materials or components of the electroplating additives are not specifically limited.

[0044] Step S4: The area on the first surface of the battery substrate where the metal electrode is to be disposed, which is located on the same side of the silicon substrate, and the metal layer on the remaining mask layer are used as the cathode and anode, respectively, and electroplating is performed, so that the metal in the metal layer on the remaining mask layer is electroplated onto the area on the first surface of the battery substrate where the metal electrode is to be disposed, so as to form the metal electrode of the battery substrate.

[0045] The inventors discovered that the main reason why the distance between the cathode and anode is relatively large in the prior art, ranging from 1 to 100 mm, is that in the prior art, the area on the solar cell where the metal electrode is to be set is opposite to the anode of the electroplating equipment, the movement path of the metal ions is basically perpendicular to the first surface, and the distance between the anode of the electroplating equipment and the area on the solar cell where the metal electrode is to be set is relatively large. Figure 5 A partial structural schematic diagram of the fourth type of solar cell in an embodiment of the present invention is shown. Figure 6 A schematic diagram illustrating the electroplating principle in an embodiment of the present invention is shown. (Refer to...) Figure 5 , Figure 6 As shown, Figure 6The lines with arrows illustrate the movement of metal ions during the electroplating process in this embodiment of the invention. On the same side of the silicon substrate, the area on the first surface of the battery substrate 1 where the metal electrode is to be disposed, and the metal layer 3 on the remaining mask layer 2, are used as the cathode and anode, respectively, for electroplating. During the electroplating process, the entire battery substrate 1 is immersed in the electroplating solution. The electroplating apparatus does not require an anode. Through the distribution of the transverse electric field, metal ions move laterally from the metal layer 3 on the remaining mask layer 2 to the area on the first surface of the battery substrate 1 where the metal electrode is to be disposed, thus forming the metal electrode 4 of the battery substrate 1. During the electroplating process to form the metal electrode 4, the metal layer 3 on the remaining mask layer 2, which serves as the anode, is continuously consumed and thinned, while the area on the first surface of the battery substrate 1 where the metal electrode is to be disposed, which serves as the cathode, continuously thickens. The area on the first surface of the battery substrate 1, which serves as the cathode, where a metal electrode is to be disposed, and the metal layer 3 on the remaining mask layer 2, which serves as the anode, are located on the same side of the silicon substrate. During the electroplating process to form the metal electrode 4, the distance between the anode and the cathode is: the distance between the area on the first surface of the battery substrate 1 where a metal electrode is to be disposed and the metal layer 3 on the remaining mask layer 2, which are located on the same side of the silicon substrate. In this embodiment of the invention, the distance between the anode and the cathode is only at the micrometer level. Compared with the 1-100mm in the prior art, the distance between the anode and the cathode in this embodiment of the invention is greatly reduced, which not only reduces the difficulty and cost of electroplating, but also enables the nearby replenishment of metal ions, improves the replenishment speed of metal ions, and increases the speed of mass production of metal electrode electroplating.

[0046] It should be noted that before electroplating, the metal layer 3 on the remaining mask layer 2 and the area on the first surface of the battery substrate 1 where the metal electrode is to be placed must be disconnected or separated to ensure that the electroplating proceeds normally.

[0047] It should be noted that the metal electrode can be a single-layer or multi-layer structure. In the case of a multi-layer metal electrode, each layer can be made of only one material. For multi-layer metal electrodes, electroplating can be performed multiple times; for example, electroplating can be performed once for each layer. In this embodiment of the invention, no specific limitation is made in this regard.

[0048] Figure 7 A partial structural schematic diagram of a fifth type of solar cell according to an embodiment of the present invention is shown. Optionally, refer to... Figure 5 As shown, after electroplating, residual metal remains on the remaining mask layer 2. (Refer to...) Figure 7As shown, if there is residual metal on the remaining mask layer 2, after step S4 above, the method further includes the following step: removing the residual metal on the remaining mask layer 2 to avoid the residual metal on the remaining mask layer 2 from adversely affecting the energy of the solar cell. If there is no residual metal on the remaining mask layer 2, this step can be omitted.

[0049] Optionally, if the material of the mask layer 2 is photoresist, a first alkaline solution can be used to remove the remaining metal on the mask layer 2. The metal used to make the metal electrode is easy to remove with an alkaline solution and has virtually no adverse effect on the solar cell.

[0050] Optionally, the first alkaline solution can be obtained by mixing ammonia solution with a concentration of 1.8-2.4 mol / L and hydrogen peroxide solution with a concentration of 0.55-0.66 mol / L. This first alkaline solution facilitates the removal of residual metal from the remaining mask layer 2. For example, the first alkaline solution can be obtained by mixing ammonia solution with a concentration of 2.11 mol / L and hydrogen peroxide solution with a concentration of 0.66 mol / L.

[0051] Figure 8 A partial structural schematic diagram of a sixth type of solar cell according to an embodiment of the present invention is shown. Optionally, refer to... Figure 8 As shown, when the mask layer 2 is a non-anti-reflection film, after forming the metal electrode 4 of the battery substrate 1, the method may further include: removing the remaining mask layer 2 to avoid the mask layer from adversely affecting the energy of the solar cell. When the mask layer 2 is an anti-reflection film, the anti-reflection film can reduce reflection in the solar cell and is a structure that the solar cell can have, so this step can be omitted.

[0052] Optionally, if the material of the mask layer 2 is photoresist, a second alkaline solution can be used to remove the remaining mask layer 2. The material of the mask layer 2 is easy to remove with an alkaline solution and has virtually no adverse effect on the solar cell.

[0053] Optionally, whether the first alkaline solution and the second alkaline solution are the same is not specifically limited. If the first alkaline solution and the second alkaline solution are the same, a single alkaline solution can be used to remove both the residual metal on the remaining mask layer 2 and the remaining mask layer 2 in one step, simplifying the process and saving time. If the first alkaline solution and the second alkaline solution are different, it facilitates the recycling of the residual metal on the remaining mask layer 2. In this embodiment of the invention, this is not specifically limited.

[0054] Optionally, the second alkaline solution includes a 0.1-0.3 mol / L sodium hydroxide solution, which facilitates the removal of the remaining mask layer 2. For example, the second alkaline solution can be a 0.2 mol / L sodium hydroxide solution. After soaking in the second alkaline solution for 30 seconds, the layer is rinsed with deionized water.

[0055] Figure 9 A schematic diagram of the structure of an HJT battery substrate according to an embodiment of the present invention is shown. (Refer to...) Figure 9 As shown, in an HJT (Heterojunction) solar cell, the cell substrate 1 may include: a front-side TCO (Transparent Conductive Oxide) film 101, the thickness of which can be 20-110 nm; an a-Si:H / µc-SiOx:H(n) N-type hydrogen-doped amorphous silicon / microcrystalline silicon oxide passivation layer 102, the thickness of which can be 1-50 nm; an a-Si(i) front-side intrinsic amorphous silicon passivation layer 103, the thickness of which can be 1-20 nm; and an a-Si(i) front-side intrinsic amorphous silicon buffer layer 104, the thickness of which can be 1- 10nm, Si(n) N-type silicon substrate 105, the thickness of silicon substrate 105 can be 80-200µm, a-Si(i) back intrinsic amorphous silicon buffer layer 106, the thickness of buffer layer 106 can be 1-10nm, a-Si(i) back intrinsic amorphous silicon passivation layer 107, its thickness can be 1-20nm, a-Si:H(p) P-type amorphous silicon emitter 108, its thickness can be 1-50nm, back TCO (Transparent Conductive Oxide) transparent conductive oxide film 109, the thickness of back TCO film 109 can be 20-110nm.

[0056] Figure 10 A partial structural schematic diagram of the first type of HJT solar cell in an embodiment of the present invention is shown. Figure 11 A partial structural schematic diagram of the second type of HJT solar cell in an embodiment of the present invention is shown. Figure 11 A schematic diagram is shown after a groove is created in the HJT battery substrate. Figure 12 A partial structural schematic diagram of the third type of HJT solar cell in an embodiment of the present invention is shown. Figure 12 A schematic diagram is shown after a metal layer has been deposited on an HJT battery substrate. Figure 13 A partial structural schematic diagram of the fourth HJT solar cell in an embodiment of the present invention is shown. Figure 14 A partial structural schematic diagram of the fifth type of HJT solar cell in an embodiment of the present invention is shown. Figure 15 A schematic diagram of the structure of an HJT solar cell according to an embodiment of the present invention is shown.

[0057] Optional, refer to Figure 12 As shown, when the battery substrate is an HJT battery substrate, after the metal layers are deposited, they are all located on the same side of the silicon substrate 105. The metal layer on the bottom of the tank is farther from the surface of the silicon substrate 105 and closer to the surface of the mask layer 2 than the metal layers on the remaining mask layers, thus being closer to the silicon substrate 105. This leaves space for electroplating metal electrodes on the bottom of the tank, and the fact that they are all located on the same side of the silicon substrate 105 allows for the separation or isolation of the metal layers on the bottom of the tank from the metal layers on the remaining mask layers. Specifically, the metal layer 312 on the bottom of the tank on the light-facing side of the silicon substrate 105 is farther from the surface of the silicon substrate 105 and closer to the silicon substrate 105 than the metal layer 311 on the front mask layer 21, which is closer to the surface of the front mask layer 21. The metal layer 322 on the bottom of the tank on the back-light-facing side of the silicon substrate 105 is farther from the surface of the silicon substrate 105 and closer to the silicon substrate 105 than the metal layer 321 on the back mask layer 22, which is closer to the surface of the back mask layer 225.

[0058] Optional, refer to Figure 12 As shown, when the battery substrate is an HJT battery substrate, step S4 can be as follows: The metal layer on the bottom of the tank and the metal layer on the remaining mask layer, both located on the same side of the silicon substrate 105, are used as the cathode and anode, respectively, for electroplating. This allows the metal in the remaining mask layer to be electroplated onto the metal layer on the bottom of the tank, which can serve as a seed layer. Before electroplating, the metal layer on the bottom of the tank and the metal layer on the remaining mask layer are disconnected to ensure smooth electroplating.

[0059] The opening of the tank 23 is located at the end of the tank 23 furthest from the silicon substrate 105. The bottom of the tank 23 is opposite to the opening of the tank 23, and the tank wall is located between the opening and the bottom of the tank. Optionally, refer to... Figure 11As shown, when the battery substrate is an HJT battery substrate, and the surface of the mask layer away from the silicon substrate 105 obstructs the tank wall, during the metal layer deposition process, due to the obstruction of the tank wall by the surface of the mask layer away from the silicon substrate 105, no metal layer is deposited on the tank wall of the tank body 23. That is, during the metal layer deposition process, all layers are located on the same side of the silicon substrate 105. The metal layer on the bottom of the tank and the remaining metal layer on the mask layer are naturally disconnected. The metal layer on the mask layer and the metal layer on the bottom of the tank are not connected, allowing for direct electroplating, reducing steps and simplifying the process. When the surface of the mask layer away from the silicon substrate 105 obstructs the tank wall, the shape of the tank body 23 can be a shape with a small opening and a large belly. The tank wall of the tank 23 can be a planar arm or a curved wall. The tank wall of the tank 23 can be a single unit or composed of multiple sub-tank wall segments. The shape of each sub-tank wall segment is not specifically limited, as long as the opening of the tank 23 is narrow, and during the metal deposition process, the surface of the mask layer away from the silicon substrate 105 blocks the tank wall, preventing metal deposition on the tank wall. For example, the shape of the tank 23 can be such that the projected area of ​​the tank wall's cross-section on the first surface is larger than the projected area of ​​the slot opening on the first surface, and the projection of the tank wall's cross-section on the first surface covers the projection of the slot opening's cross-section on the first surface, with this cross-section parallel to the first surface. In this embodiment of the invention, the specific shape of the tank 23 is not specifically limited.

[0060] In other cases, prior to electroplating, the method may further include the following steps: removing the metal layers on the tank walls so that they are all located on the same side of the silicon substrate 105, and disconnecting the metal layers on the tank bottom and the remaining mask layer to ensure smooth electroplating. These other cases involve the surface of the mask layer away from the silicon substrate 105 not obstructing the tank walls.

[0061] Reference Figure 10 As shown, optionally, when the battery substrate is an HJT battery substrate, the first surface of the HJT battery substrate can be the light-facing surface and the back-light-facing surface of the HJT battery substrate. Step S1 above may include: providing a front mask layer 21 on the light-facing surface of the battery substrate, and / or providing a back mask layer 22 on the back-light-facing surface of the battery substrate. The front mask layer 21 may be provided only on the light-facing surface of the battery substrate, in which case the front metal electrode can be fabricated by the preparation method of the present invention. Alternatively, the back mask layer 22 may be provided only on the back-light-facing surface of the battery substrate, in which case the back metal electrode can be fabricated by the preparation method of the present invention. Or, as... Figure 10As shown, both the front and back metal electrodes are prepared using the method of this invention. In this embodiment, no specific limitations are made. The front mask layer 21 and the back mask layer 22 can be applied by roller coating. A positive photoresist with a viscosity of 100 cps (mPascals-seconds) can be coated onto the surface of the front TCO film 101 by roller coating, with a thickness of 15 μm. After coating, the battery substrate is placed in an oven for curing at 90°C for 60 seconds. After curing, the back surface of the battery substrate is coated in the same way. Both the front mask layer 21 and the back mask layer 22 can be made of photoresist.

[0062] Reference Figure 11 As shown, optionally, when the battery substrate is an HJT battery substrate, the above step S2 can be: forming a groove in the front mask layer 21, and / or forming a groove in the back mask layer 22.

[0063] Reference Figure 12 As shown, optionally, when the battery substrate is an HJT battery substrate, step S3 above can be: depositing a front metal layer 31 on the remaining front mask layer 21 and on the bottom of the trench on the light-facing side of the battery substrate, forming a metal layer 311 on the remaining front mask layer 21 and a metal layer 312 on the bottom of the trench on the light-facing side of the battery substrate. And / or, depositing a back metal layer 32 on the remaining back mask layer 22 and on the bottom of the trench on the back side of the battery substrate, forming a metal layer 321 on the remaining back mask layer 22 and a metal layer 322 on the bottom of the trench on the back side of the battery substrate.

[0064] For example, magnetron sputtering can be used to deposit a front metal layer 31 and a back metal layer 32, both of which can have a thickness of 200 nm. Optionally, other metal layers, such as Ti, Ni, Sn, Ag, etc., can be present between the metal electrode and the TCO. Alternatively, a compound layer, such as TiN or a self-assembly monolayer, can also be present between the metal electrode and the TCO. The thickness of other metal layers and compound layers can be between 1 and 50 nm, serving to enhance the adhesion between the metal electrode and the TCO.

[0065] Reference Figure 12 , Figure 13As shown, optionally, when the battery substrate is an HJT battery substrate, step S4 can be as follows: The metal layer 312 on the bottom of the tank on the light-facing side of the silicon substrate 105 and the metal layer 311 on the remaining front mask layer 21 are used as the cathode and anode, respectively, for electroplating. This allows the metal in the remaining metal layer 311 on the front mask layer 21 to be electroplated onto the metal layer 312 on the bottom of the tank on the light-facing side of the silicon substrate 105, continuously reducing the thickness of the remaining metal layer 311 on the front mask layer 21 to form the front metal electrode 41. Before electroplating, the metal layer 312 on the bottom of the tank on the light-facing side of the silicon substrate 105 and the metal layer 311 on the remaining front mask layer 21 are disconnected to ensure smooth electroplating. And / or, the metal layer 322 on the bottom of the tank on the backlight side of the silicon substrate 105 and the metal layer 321 on the remaining back mask layer 22 are used as the cathode and anode, respectively, for electroplating. This allows the metal in the remaining metal layer 321 on the back mask layer 22 to be electroplated onto the metal layer 322 on the bottom of the tank on the backlight side of the silicon substrate 105, and the thickness of the remaining metal layer 321 on the back mask layer 22 is continuously reduced to form the back metal electrode 42. Before electroplating, the metal layer 322 on the bottom of the tank on the backlight side of the silicon substrate 105 and the metal layer 321 on the remaining back mask layer 22 are disconnected to ensure smooth electroplating. The thickness of both the formed front metal electrode 41 and the back metal electrode 42 can be approximately 15 μm.

[0066] like Figure 13 , Figure 14 As shown, after electroplating, metal residue remains on both the front mask layer 21 and the back mask layer 22, which can be removed using a first alkaline solution. Neither the front mask layer 21 nor the back mask layer 22 is an anti-reflective coating. (Refer to...) Figure 15 As shown, if the materials of the front mask layer 21 and the back mask layer 22 are photoresist, they can be removed using a second alkaline solution. Figure 15 The image shows the prepared HJT solar cell.

[0067] Figure 16 A schematic diagram of the structure of an HBC battery substrate according to an embodiment of the present invention is shown. (Refer to...) Figure 16 As shown, in an HBC (Heterojunction Back Contact) solar cell, the cell substrate 1 may include: a front silicon nitride layer 110, a front n layer 111, a front i layer 112, a silicon substrate 105, a back i layer 113, an n-type layer 114, a p-type layer 115, an isolation layer 116, and a back TCO film 109. The n-type layer 114 and the p-type layer 115 are spaced apart, and the isolation layer 116 is located between the n-type layer 114 and the p-type layer 115.

[0068] Figure 17 A partial structural schematic diagram of the first type of HBC solar cell in an embodiment of the present invention is shown. Figure 18 A partial structural schematic diagram of the second type of HBC solar cell in an embodiment of the present invention is shown. Figure 18 A schematic diagram is shown after a groove is created in the HBC battery substrate. Figure 19 A partial structural schematic diagram of the third type of HBC solar cell in an embodiment of the present invention is shown. Figure 19 A schematic diagram is shown after a metal layer has been deposited on the HBC battery substrate. Figure 20 A partial structural schematic diagram of the fourth HBC solar cell in an embodiment of the present invention is shown. Figure 21 A partial structural schematic diagram of the fifth type of HBC solar cell in an embodiment of the present invention is shown. Figure 22 A schematic diagram of the structure of an HBC solar cell according to an embodiment of the present invention is shown.

[0069] Optional, refer to Figure 19 As shown, when the battery substrate is an HBC battery substrate, after the metal layers are deposited, they are all located on the same side of the silicon substrate 105. The metal layer on the bottom of the tank is farther from the surface of the silicon substrate 105 and closer to the surface of the mask layer than the metal layer on the remaining mask layer, thus being closer to the silicon substrate 105. Consequently, space is left on the bottom of the tank for electroplating metal electrodes, and the fact that they are all located on the same side of the silicon substrate 105 allows for the separation or isolation of the metal layer on the bottom of the tank from the metal layer on the remaining mask layer. That is, the metal layer 322 on the bottom of the tank on the backlight side of the silicon substrate 105 is farther from the surface of the silicon substrate 105 and closer to the surface of the back mask layer 22 than the metal layer 321 on the back mask layer 22, thus being closer to the silicon substrate 105.

[0070] Optional, refer to Figure 19 , Figure 20 As shown, when the battery substrate is an HBC battery substrate, step S4 can be as follows: The metal layer on the bottom of the tank and the remaining metal layer on the same side of the silicon substrate 105 are used as the cathode and anode, respectively, for electroplating. This allows the metal in the remaining metal layer on the mask layer to be electroplated onto the metal layer on the bottom of the tank, which can serve as a seed layer. Before electroplating, the metal layer on the bottom of the tank and the remaining metal layer on the mask layer, both located on the same side of the silicon substrate 105, are disconnected to ensure smooth electroplating.

[0071] The opening of the tank 23 is located at the end of the tank 23 furthest from the silicon substrate 105. The bottom of the tank 23 is opposite to the opening of the tank 23, and the tank wall is located between the opening and the bottom of the tank. Optionally, refer to... Figure 18 , 19As shown, when the battery substrate is an HBC battery substrate, the surface of the mask layer away from the silicon substrate 105 may obstruct the tank wall, or the surface of the mask layer away from the silicon substrate 105 may not obstruct the tank wall. The shape of the tank 23 can be referred to the aforementioned description of the HJT battery substrate, and will not be repeated here to avoid repetition. In the case where the surface of the mask layer away from the silicon substrate 105 obstructs the tank wall, during the deposition of the metal layer, due to the obstruction of the tank wall by the surface of the mask layer away from the silicon substrate 105, no metal layer is deposited on the tank wall of the tank 23. They are all located on the same side of the silicon substrate 105. The metal layer on the bottom of the tank and the remaining metal layer on the mask layer are naturally disconnected. Therefore, the metal layer on the mask layer and the metal layer on the bottom of the tank are not connected, and electroplating can be performed directly, reducing steps and simplifying the process.

[0072] In other cases, prior to electroplating, the method may also include the following steps: removing the metal layers on the tank walls so that they are all located on the same side of the silicon substrate 105, and disconnecting the metal layers on the bottom of the tank and the remaining mask layer to ensure the smooth progress of electroplating.

[0073] Reference Figure 17 As shown, optionally, when the battery substrate is an HBC battery substrate, the first surface of the HBC battery substrate can be the back surface of the HBC battery substrate. Step S1 above may include: depositing a back mask layer 22 on the back surface of the battery substrate. The back mask layer 22 can be deposited by coating, and the material of the back mask layer 22 can be photoresist.

[0074] Reference Figure 18 As shown, optionally, when the battery substrate is an HBC battery substrate, step S2 can be: forming grooves in the back mask layer 22. For example, if the material of the back mask layer 22 is photoresist, it can be dried and then exposed and developed to form the corresponding electrode pattern and grooves.

[0075] Reference Figure 19 As shown, optionally, when the battery substrate is an HBC battery substrate, the above step S3 can be: depositing a back metal layer 32 on the remaining back mask layer 22 and on the bottom of the trench on the back surface of the battery substrate, forming a metal layer 321 on the remaining back mask layer 22 and a metal layer 322 on the bottom of the trench on the back surface of the battery substrate.

[0076] Reference Figure 19 , Figure 20As shown, optionally, when the battery substrate is an HBC battery substrate, step S4 can be as follows: the metal layer 322 on the bottom of the tank on the backlight side of the silicon substrate 105 and the metal layer 321 on the remaining back mask layer 22 are used as the cathode and anode, respectively, for electroplating, so that the metal in the metal layer 321 on the remaining back mask layer 22 is electroplated onto the metal layer 322 on the bottom of the tank on the backlight side of the silicon substrate 105, and the thickness of the metal layer 321 on the remaining back mask layer 22 is continuously reduced to form the back metal electrode 42. Before electroplating, the metal layer 322 on the bottom of the tank on the backlight side of the silicon substrate 105 and the metal layer 321 on the remaining back mask layer 22 are disconnected to ensure that the electroplating proceeds smoothly.

[0077] like Figure 20 As shown, after electroplating, metal residue remains on the back mask layer 22. If the material of the back mask layer 22 is photoresist, it can be removed using a first alkaline solution. The back mask layer 22 is not an anti-reflective film. (Refer to...) Figure 21 As shown, if the material of the back mask layer 22 is photoresist, it can be removed using a second alkaline solution. Figure 22 The image shows the prepared HBC solar cell.

[0078] Figure 23 A schematic diagram of the structure of a TOPCon battery substrate according to an embodiment of the present invention is shown. (Refer to...) Figure 23 As shown, in a TOPCon (Tunnel Oxide Passivated Contact) solar cell, the cell substrate 1 may include: a front silicon nitride layer 110, an aluminum oxide film 117, a boron-doped emitter 118, a silicon substrate 105, a back ultrathin oxide film 119, a phosphorus-doped polycrystalline silicon film 120, and a back silicon nitride layer 121. The silicon substrate 105 can be an N-type silicon substrate. The fabrication process of the TOPCon cell substrate 1 can be as follows: After texturing and cleaning the silicon substrate 105, high-temperature boron doping is performed on the light-facing side of the silicon substrate 105 to form a full-surface boron-doped emitter 118, and high-temperature phosphorus doping is performed on the back-facing side of the silicon substrate 105 to form a back field. An aluminum oxide film 117 and a front silicon nitride layer 110 are sequentially grown on the light-facing side, and a back ultrathin oxide film 119, a phosphorus-doped polycrystalline silicon film 120, and a back silicon nitride layer 121 are sequentially grown on the back-facing side.

[0079] Figure 24 A partial structural schematic diagram of the first type of TOPCon solar cell in an embodiment of the present invention is shown. Figure 25 A partial structural schematic diagram of the second type of TOPCon solar cell in an embodiment of the present invention is shown. Figure 25 A schematic diagram is shown after a groove is created in the TOPCon battery substrate. Figure 26 A partial structural schematic diagram of the third type of TOPCon solar cell in an embodiment of the present invention is shown. Figure 26 A schematic diagram is shown after a metal layer has been deposited on the TOPCon battery substrate. Figure 27 A partial structural schematic diagram of the fourth TOPCon solar cell in an embodiment of the present invention is shown. Figure 28 A partial structural schematic diagram of the fifth type of TOPCon solar cell in an embodiment of the present invention is shown. Figure 29 A partial structural schematic diagram of the sixth type of TOPCon solar cell in an embodiment of the present invention is shown. Figure 30 A schematic diagram of the structure of a TOPCon solar cell according to an embodiment of the present invention is shown.

[0080] Optional, refer to Figure 26 As shown, when the battery substrate is a TOPCon battery substrate, the above step S3 may include: depositing an electrode metal layer and a contact barrier metal layer sequentially on the remaining mask layer and on the area on the first surface of the battery substrate 1 where the metal electrode is to be disposed. The deposited contact barrier metal layer is formed between the metal electrode and the silicon substrate 105 during the subsequent electroplating process, which serves to prevent the metal electrode from contacting the silicon substrate 105 and to prevent the metal electrode from entering the silicon substrate 105.

[0081] Reference Figure 25 As shown, the shading relationship between the surface of the mask layer away from the silicon substrate 105 and the trench wall is twofold: the surface of the mask layer away from the silicon substrate 105 either blocks the trench wall or does not block it. For details on whether it blocks or not, please refer to the relevant description of the trench in the HJT battery substrate; to avoid repetition, it will not be repeated here. (Refer to...) Figure 26 , Figure 27As shown, when the battery substrate is a TOPCon battery substrate and the surface of the mask layer away from the silicon substrate 105 obstructs the trench wall, after step S3, the method may further include the following step: during the trenching process in the silicon nitride layer, the electrode metal layer and contact barrier metal layer on the bottom of the trench are removed, so that the area on the first surface of the battery substrate to be provided with metal electrodes is exposed. That is, during the fabrication of the TOPCon solar cell, the front silicon nitride layer 110 and the back silicon nitride layer 121 need to be trenched to expose the alumina film 117 and the phosphorus-doped polycrystalline silicon film 120. During the trenching process of the front silicon nitride layer 110 and the back silicon nitride layer 121, the electrode metal layer and contact barrier metal layer on the bottom of the trench are removed, eliminating the need to specifically remove the electrode metal layer and contact barrier metal layer on the bottom of the trench, thus simplifying the process. Since the surface of the mask layer, which is far from the silicon substrate 105, blocks the tank wall, there are no electrode metal layers and contact barrier metal layers on the tank wall during the deposition of electrode metal layers and contact barrier metal layers. This allows the electrode metal layers and contact barrier metal layers on the bottom of the tank to be naturally isolated or disconnected from the electrode metal layers and contact barrier metal layers on the mask layer, ensuring the smooth progress of electroplating and simplifying the process.

[0082] If the battery substrate is a TOPCon battery substrate, and in other cases, after step S3, the method may further include the following steps: during the trenching process in the silicon nitride layer, the electrode metal layer and contact barrier metal layer on the trench wall, as well as the electrode metal layer and contact barrier metal layer on the trench bottom, are removed, so that the area on the first surface of the battery substrate where the metal electrode is to be disposed is exposed. Figure 26 As shown, the metal layer 33 on the tank wall is removed. That is, in the process of fabricating TOPCon solar cells, it is necessary to create grooves in the front silicon nitride layer 110 and the back silicon nitride layer 121 to expose the alumina film 117 and the phosphorus-doped polycrystalline silicon film 120. In the process of creating grooves in the front silicon nitride layer 110 and the back silicon nitride layer 121, the electrode metal layer and contact barrier metal layer on the tank wall and the electrode metal layer and contact barrier metal layer on the tank bottom are also removed. There is no need to separately remove the electrode metal layer and contact barrier metal layer on the tank wall and the electrode metal layer and contact barrier metal layer on the tank bottom, which simplifies the process. In other cases, the surface of the mask layer away from the silicon substrate 105 does not block the tank wall. During the deposition of the electrode metal layer and the contact barrier metal layer, there may be electrode metal layers and contact barrier metal layers on the tank wall. Removing the electrode metal layers and contact barrier metal layers on the tank wall will separate or disconnect the electrode metal layers and contact barrier metal layers on the bottom of the tank from those on the mask layer, thus ensuring the smooth progress of electroplating.

[0083] Optional, refer to Figure 27 , Figure 28 , Figure 29As shown, when the battery substrate is a TOPCon battery substrate, step S4 can be as follows: The area on the same side of the silicon substrate 105 where the electrode metal layer and contact barrier metal layer have been removed from the bottom of the tank, and the remaining contact barrier metal layer on the mask layer, are used as the cathode and anode, respectively, for the first electroplating. This allows the metal in the remaining contact barrier metal layer on the mask layer to be electroplated onto the area on the bottom of the tank where the electrode metal layer and contact barrier metal layer have been removed. Before the first electroplating, the area on the same side of the silicon substrate 105 where the electrode metal layer and contact barrier metal layer have been removed from the bottom of the tank, and the remaining contact barrier metal layer on the mask layer, are disconnected to ensure smooth electroplating. That is, during the first electroplating process, there may be no seed layer on the bottom of the tank. The first electroplating forms a contact barrier metal layer between the metal electrode and the silicon substrate 105, preventing the metal electrode from contacting the silicon substrate 105 and preventing the electrode metal from entering the silicon substrate 105. Next, the area on the same side of the silicon substrate 105 where the contact barrier metal layer is plated on the bottom of the tank, and the remaining electrode metal layer on the mask layer, are used as the cathode and anode, respectively, for a second electroplating. This allows the metal in the remaining electrode metal layer on the mask layer to be plated into the area on the bottom of the tank where the contact barrier metal layer is plated. After electroplating, a contact barrier metal layer remains between the electrode metal layer on the bottom of the tank and the silicon substrate 105, preventing the electrode metal from contacting the silicon substrate 105 and preventing the electrode metal from entering the silicon substrate 105, thus preventing ghosting and mushroom-shaped cross-sections of the metal grid lines. Before the second electroplating, the area on the same side of the silicon substrate 105 where the contact barrier metal layer is plated on the bottom of the tank and the remaining electrode metal layer on the mask layer are disconnected to ensure smooth electroplating.

[0084] Reference Figure 24 As shown, optionally, when the battery substrate is a TOPCon battery substrate, the first surface of the TOPCon battery substrate can be the light-facing surface and the back-light-facing surface of the TOPCon battery substrate. Step S1 above may include: providing a front mask layer 21 on the light-facing surface of the battery substrate, and / or providing a back mask layer 22 on the back-light-facing surface of the battery substrate. The front mask layer 21 may be provided only on the light-facing surface of the battery substrate, in which case the front metal electrode can be fabricated by the preparation method of the present invention. Alternatively, the back mask layer 22 may be provided only on the back-light-facing surface of the battery substrate, in which case the back metal electrode can be fabricated by the preparation method of the present invention. Or, as... Figure 24 As shown, both the front metal electrode and the back metal electrode are prepared by the method of the present invention.

[0085] Reference Figure 25As shown, optionally, when the battery substrate is a TOPCon battery substrate, the above step S2 can be: forming a groove in the front mask layer 21, and / or forming a groove in the back mask layer 22.

[0086] Reference Figure 26 As shown, optionally, when the battery substrate is a TOPCon battery substrate, the above steps of sequentially depositing electrode metal layers and contact barrier metal layers include: sequentially depositing a front electrode metal layer 3111 and a front contact barrier metal layer 3112 on the remaining front mask layer 21 and on the bottom of the trench on the light-facing side of the battery substrate. And / or, sequentially depositing a back electrode metal layer 3211 and a back contact barrier metal layer 3212 on the remaining back mask layer 22 and on the bottom of the trench on the back side of the battery substrate.

[0087] Reference Figure 27 As shown, optionally, the silicon nitride layer includes a front silicon nitride layer 110 and a back silicon nitride layer 121. During the trenching process in the silicon nitride layer, the electrode metal layer and the contact barrier metal layer on the bottom of the trench are removed. This includes: when the front mask layer 21 is away from the silicon substrate 105 and the trench wall of the trench located on the light-facing side of the silicon substrate 105 is blocked, during the trenching process in the front silicon nitride layer 110, the front electrode metal layer 3111 and the front contact barrier metal layer 3112 on the bottom of the trench on the light-facing side of the silicon substrate 105 are removed; and / or, when the back mask layer 22 is away from the silicon substrate 105 and the trench wall of the trench located on the back light-facing side of the silicon substrate 105 is blocked, during the trenching process in the back silicon nitride layer 121, the back electrode metal layer 3211 and the back contact barrier metal layer 3212 on the bottom of the trench on the back light-facing side of the silicon substrate 105 are removed. There is no need to specifically remove the front electrode metal layer 3111 and the front contact barrier metal layer 3112 on the bottom of the trench on the light-facing side of the silicon substrate 105, nor is there a need to specifically remove the back electrode metal layer 3211 and the back contact barrier metal layer 3212 on the bottom of the trench on the back-light-facing side of the silicon substrate 105, making the process simple.

[0088] Optionally, in other cases, during the trenching process in the silicon nitride layer, the electrode metal layer and contact barrier metal layer on the trench wall, and the electrode metal layer and contact barrier metal layer on the trench bottom are all removed. This includes: when the front mask layer 21 is away from the silicon substrate 105 and there is no obstruction to the trench wall of the trench body located on the light-facing side of the silicon substrate 105, during the trenching process in the front silicon nitride layer 110, the front electrode metal layer 3111 and the front contact barrier metal layer 3112 on the light-facing side of the trench wall of the silicon substrate 105, and the trench... The front electrode metal layer 3111 and the front contact barrier metal layer 3112 on the bottom are both removed; and / or, when the back mask layer 22 is away from the silicon substrate 105 and the trench wall of the trench located on the back light side of the silicon substrate 105 is not obstructed, during the trenching process in the back silicon nitride layer 121, the back electrode metal layer 3211 and the back contact barrier metal layer 3212 on the trench wall located on the back light side of the silicon substrate 105, and the back electrode metal layer 3211 and the back contact barrier metal layer 3212 on the bottom of the trench are both removed. There is no need to specifically remove the front electrode metal layer 3111 and the front contact barrier metal layer 3112 on the light-facing side of the silicon substrate 105, the front electrode metal layer 3111 and the front contact barrier metal layer 3112 on the bottom of the tank, and there is no need to specifically remove the back electrode metal layer 3211 and the back contact barrier metal layer 3212 on the back-light-facing side of the silicon substrate 105, and the back electrode metal layer 3211 and the back contact barrier metal layer 3212 on the bottom of the tank, thus simplifying the process.

[0089] Reference Figure 27 , Figure 28As shown, optionally, when the battery substrate is a TOPCon battery substrate, the first electroplating can be performed as follows: the area on the light-facing side of the silicon substrate 105 where the electrode metal layer and contact barrier metal layer have been removed, and the remaining front contact barrier metal layer 3112 on the front mask layer 21 are used as the cathode and anode, respectively, for the first electroplating. This allows the metal in the remaining front contact barrier metal layer 3112 on the front mask layer 21 to be electroplated onto the area on the light-facing side of the silicon substrate 105 where the electrode metal layer and contact barrier metal layer have been removed, and the thickness of the remaining front contact barrier metal layer 3112 on the front mask layer 21 is continuously reduced. Before the first electroplating, the area on the light-facing side of the silicon substrate 105 where the electrode metal layer and contact barrier metal layer have been removed, and the remaining front contact barrier metal layer 3112 on the front mask layer 21 are disconnected to ensure smooth electroplating. And / or, the area on the back side of the silicon substrate 105 where the electrode metal layer and contact barrier metal layer have been removed, and the remaining back contact barrier metal layer 3212 on the back mask layer 22, are used as the cathode and anode respectively for the first electroplating. This allows the metal in the remaining back contact barrier metal layer 3212 on the back mask layer 22 to be electroplated onto the area on the back side of the silicon substrate 105 where the electrode metal layer and contact barrier metal layer have been removed, thus continuously reducing the thickness of the remaining back contact barrier metal layer 3212 on the back mask layer 22. Before the first electroplating, the area on the back side of the silicon substrate 105 where the electrode metal layer and contact barrier metal layer have been removed, and the remaining back contact barrier metal layer 3212 on the back mask layer 22 are disconnected to ensure smooth electroplating.

[0090] like Figure 28 As shown, after the first electroplating is completed, there is no residue of the front contact barrier metal layer 3112 on the front mask layer 21, so the step of removing the residual front contact barrier metal is not required. Similarly, there is no residue of the back contact barrier metal layer 3212 on the back mask layer 22, so the step of removing the residual back contact barrier metal is not required.

[0091] Reference Figure 28 , Figure 29As shown, optionally, when the battery substrate is a TOPCon battery substrate, the second electroplating can be performed as follows: the area on the bottom of the tank on the light-facing side of the silicon substrate 105 where the front contact blocking metal 51 is plated and the remaining front electrode metal layer 3111 on the front mask layer 21 are used as the cathode and anode, respectively, for the second electroplating, so that the metal in the remaining front electrode metal layer 3111 on the front mask layer 21 is plated to the area on the bottom of the tank on the light-facing side of the silicon substrate 105 where the front contact blocking metal 51 is plated, forming the front metal electrode 41; before the second electroplating, the area on the bottom of the tank on the light-facing side of the silicon substrate 105 where the front contact blocking metal 51 is plated and the remaining front electrode metal layer 3111 on the front mask layer 21 are disconnected to ensure that the electroplating proceeds smoothly. And / or, the area on the back contact barrier metal 52 plated on the bottom of the tank on the backlight side of the silicon substrate 105, and the remaining back electrode metal layer 3211 on the back mask layer 22 are used as the cathode and anode, respectively, for a second electroplating. This allows the metal in the remaining back electrode metal layer 3211 on the back mask layer 22 to be electroplated onto the area on the bottom of the tank on the backlight side of the silicon substrate 105 where the back contact barrier metal 52 is plated, forming the back metal electrode 42. Before the second electroplating, the area on the bottom of the tank on the backlight side of the silicon substrate 105 where the back contact barrier metal 52 is plated and the remaining back electrode metal layer 3211 on the back mask layer 22 are disconnected to ensure smooth electroplating.

[0092] Optionally, the material of the contact barrier metal layer includes nickel, which provides good barrier properties against the electrode metal. And / or, the material of the electrode metal layer includes copper, which has good conductivity and low cost.

[0093] like Figure 29 As shown, after the second electroplating is completed, there is no residue of the front electrode metal layer on the front mask layer 21, so the step of removing the residual front electrode metal is not required. Similarly, there is no residue of the back electrode metal layer on the back mask layer 22, so the step of removing the residual back electrode metal is not required.

[0094] like Figure 30 As shown, after the metal electrode is formed, the front mask layer 21 is not a front anti-reflection film layer, so the front mask layer 21 is removed; the back mask layer 22 is not a back anti-reflection film layer, so the back mask layer 22 is removed. Figure 30 This is a schematic diagram of the structure of a TOPCon solar cell according to an embodiment of the present invention.

[0095] Optionally, when the surface of the mask layer away from the silicon substrate 105 obstructs the trench wall, the shape of the trench 23 includes at least one of the following: a frustum, a truncated cone, and a bowl-shaped structure; the shape of the trench 23 is diverse. For example, Figure 11The shape of the groove 23 shown can be a frustum structure.

[0096] This invention also provides a solar cell, which is prepared by any of the aforementioned methods for preparing solar cells. This solar cell has the same or similar beneficial effects as the aforementioned methods for preparing solar cells. The solar cell can be referred to the relevant descriptions above. To avoid repetition, it will not be repeated here.

[0097] The present application will be further explained below with reference to specific embodiments: Example 1 Reference Figures 10-15 As shown, when the battery substrate is an HJT battery substrate, the production... Figure 15 The HJT solar cell shown may include the following steps: First step, refer to Figure 10 As shown, mask layers are coated on the light-facing and back-light-facing surfaces of the HJT battery substrate. The coating method is roller coating, and the mask material is positive photoresist. First, a positive photoresist with a viscosity of 100 cps is coated onto the light-facing surface of the HJT battery substrate, i.e., the light-facing surface of the front-side TCO transparent conductive oxide film 101, with a thickness of 15 micrometers, using a roller coating method. After coating, the HJT battery substrate is placed in an oven for curing at a temperature of 90°C for 60 seconds. After curing, the same coating is performed on the back-light-facing surface of the HJT battery substrate. The first step forms a front-side photoresist mask layer 21 on the light-facing surface of the HJT battery substrate and a back-side photoresist mask layer 22 on the light-facing surface of the HJT battery substrate.

[0098] The second step, refer to Figure 11 As shown, patterned grooving is performed on the front mask layer 21 on the light-facing side and the back mask layer 22 on the back-facing side of the HJT battery substrate. Specifically, laser irradiation is used, and the area to be grooved undergoes a photochemical reaction after laser irradiation. The laser wavelength is 405 nm, the exposure time is 2 minutes, and the laser energy is 60 mJ / cm². 2 The photoresist that has undergone photochemical reaction was removed by spraying with a 1% NaHCO3 solution, and the designed metallized gate pattern was formed by development. The width of the trench is 20 µm, and the cross-section is trapezoidal. The developed HJT battery substrate was cleaned by spraying with deionized water. It was dried with hot air at 50°C and cooled with cold air at 25°C.

[0099] Third step, refer to Figure 12As shown, metal layers are deposited on the light-facing and back-facing surfaces of the patterned grooved HJT battery substrate. Specifically, a copper film layer with a thickness of 200 nm is deposited using magnetron sputtering. Because the trench cross-section is trapezoidal, the surface of the mask layer away from the silicon substrate blocks the trench wall. The metal layer on the mask layer and the metal layer on the TCO transparent conductive oxide film, located on the same side of the silicon substrate, are discontinuous, facilitating co-surface electroplating.

[0100] Step 4, refer to Figure 13 As shown, the HJT battery substrate with deposited metal layers was placed in an electroplating solution for electroplating. The electroplating solution was a copper sulfate solution mixed with electroplating additives. The metal layer on the remaining mask layer was connected to the anode, and the metal layer at the bottom of the tank was connected to the cathode. During the electroplating process, the thickness of the metal layer on the mask layer continuously decreased. After electroplating, the thickness of the metal electrode at the bottom of the tank was 15 μm.

[0101] Step 5, refer to Figure 14 As shown, the residual metal layer on the remaining mask layer is removed. Specifically, the solar cell is immersed in an ammonia / hydrogen peroxide solution (concentrations of 2.11 mol / L and 0.66 mol / L, respectively) for 20 seconds.

[0102] Step 6, refer to Figure 15 As shown, the mask layer is removed. Specifically, the solar cell is immersed in a 0.2 mol / L NaOH solution for 30 seconds and rinsed with deionized water to obtain the HJT solar cell.

[0103] Example 2 Reference Figure 24 Figure 30 As shown, when the battery substrate is a TOPCon battery substrate, the production... Figure 30 The TOPCon solar cell shown may include the following steps: First step, refer to Figure 24 As shown, a mask layer is coated on both the light-facing and back-facing surfaces of the TOPCon battery substrate. The mask material is a positive photoresist. The specific steps are similar to the first step in Example 1 described above.

[0104] The second step, refer to Figure 25 As shown, the front mask layer 21 on the light-facing side and the back mask layer 22 on the back-facing side of the TOPCon battery substrate are patterned and grooved using a laser. The cross-section of the groove is rectangular. That is, the surface of the mask layer away from the silicon substrate does not obstruct the groove wall. The remaining steps in the second step are similar to the second step in the aforementioned embodiment 1.

[0105] Third step, refer to Figure 26As shown, a contact barrier metal layer made of Ni and an electrode metal layer made of Cu are sequentially deposited on the light-facing side of the patterned TOPCon battery substrate. On the back-light-facing side of the patterned TOPCon battery substrate, a contact barrier metal layer made of Ni and an electrode metal layer made of Cu are sequentially deposited.

[0106] Step 4, refer to Figure 27 As shown, the laser etching creates openings. While creating grooves in the front silicon nitride layer 110, since the mask layer's surface away from the silicon substrate does not obstruct the groove walls, the Ni contact barrier metal layer and Cu electrode metal layer on the groove sidewalls and bottom are removed, exposing the alumina film 117. Similarly, while creating grooves in the back silicon nitride layer 121, the Ni contact barrier metal layer and Cu electrode metal layer on the groove sidewalls and bottom are removed, exposing the phosphorus-doped polycrystalline silicon film 120.

[0107] Step 5, refer to Figure 28 As shown, the area on the light-facing side of the silicon substrate 105 where the electrode metal layer and contact barrier metal layer have been removed, and the remaining front contact barrier metal layer 3112 on the front mask layer 21 are used as the cathode and anode, respectively, for the first electroplating. This causes the metal in the remaining front contact barrier metal layer 3112 on the front mask layer 21 to be electroplated onto the area on the light-facing side of the silicon substrate 105 where the electrode metal layer and contact barrier metal layer have been removed, and the thickness of the remaining front contact barrier metal layer 3112 on the front mask layer 21 is continuously reduced. The area on the back side of the silicon substrate 105 where the electrode metal layer and contact barrier metal layer have been removed, and the remaining back contact barrier metal layer 3212 on the back mask layer 22, are used as the cathode and anode for the first electroplating. This process electroplats the metal from the remaining back contact barrier metal layer 3212 on the back side of the silicon substrate 105 onto the area where the electrode metal layer and contact barrier metal layer have been removed, resulting in a continuous reduction in the thickness of the remaining back contact barrier metal layer 3212 on the back mask layer 22. After the first electroplating is completed, there is no residue of the front contact barrier metal layer 3112 on the front mask layer 21, nor is there any residue of the back contact barrier metal layer 3212 on the back mask layer 22.

[0108] Step 6, refer to Figure 29As shown, the area on the bottom of the tank on the light-facing side of the silicon substrate 105 where the front contact barrier metal 51 is plated, and the remaining front electrode metal layer 3111 on the front mask layer 21 are used as the cathode and anode, respectively, for a second electroplating. This allows the metal in the remaining front electrode metal layer 3111 on the front mask layer 21 to be plated onto the area on the bottom of the tank on the light-facing side of the silicon substrate 105 where the front contact barrier metal 51 is plated, forming a front metal electrode 41. The area on the bottom of the tank on the back-light-facing side of the silicon substrate 105 where the back contact barrier metal 52 is plated, and the remaining back electrode metal layer 3211 on the back mask layer 22 are used as the cathode and anode, respectively, for a second electroplating. This allows the metal in the remaining back electrode metal layer 3211 on the back mask layer 22 to be plated onto the area on the bottom of the tank on the back-light-facing side of the silicon substrate 105 where the back contact barrier metal 52 is plated, forming a back metal electrode 42. After the second electroplating was completed, there was no residue of the front electrode metal layer 3111 on the front mask layer 21, and no residue of the back electrode metal layer 3211 on the back mask layer 22.

[0109] Step 7, refer to Figure 30 As shown, the mask layer is removed. The specific steps are similar to step six in Example 1 above, to obtain the TOPCon solar cell.

[0110] It should be noted that, for the sake of simplicity, the method embodiments are all described as a series of actions. However, those skilled in the art should understand that the embodiments of this application are not limited to the described order of actions, because according to the embodiments of this application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily essential to the embodiments of this application.

[0111] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0112] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0113] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for preparing a solar cell, characterized in that, include: A mask layer is disposed on a first surface of a battery substrate; the battery substrate includes a silicon substrate; the first surface of the battery substrate is the surface on which a metal electrode is to be disposed; A groove is formed in the mask layer so that the area on the first surface of the battery substrate to be provided with metal electrodes is exposed. Metal layers are deposited on the remaining mask layer and on the area on the first surface of the battery substrate where metal electrodes are to be disposed; both are located on the same side of the silicon substrate, and the metal layers on the remaining mask layer and the area on the first surface of the battery substrate where metal electrodes are to be disposed are disconnected. The areas on the first surface of the battery substrate where metal electrodes are to be disposed, which are all located on the same side of the silicon substrate, and the remaining metal layer on the mask layer are used as the cathode and anode, respectively, and electroplating is performed so that the metal in the remaining metal layer on the mask layer is electroplated onto the areas on the first surface of the battery substrate where metal electrodes are to be disposed, thereby forming the metal electrodes of the battery substrate.

2. The method for preparing a solar cell according to claim 1, characterized in that, The opening of the tank is located at the end of the tank away from the silicon substrate, and the bottom of the tank is distributed opposite to the opening of the tank; when the battery substrate is an HJT battery substrate or an HBC battery substrate: After the metal layers are deposited, they are all located on the same side of the silicon substrate. The metal layer on the bottom of the trench is farther away from the surface of the silicon substrate and closer to the surface of the mask layer than the metal layer on the remaining mask layer, and closer to the silicon substrate. Electroplating includes: using a metal layer located on the same side of the silicon substrate, on the bottom of the tank and the remaining metal layer on the mask layer as the cathode and anode, respectively, for electroplating.

3. The method for preparing a solar cell according to claim 2, characterized in that, The tank wall is located between the opening of the tank and the bottom of the tank; when the surface of the mask layer away from the silicon substrate blocks the tank wall, during the deposition of the metal layer: they are all located on the same side of the silicon substrate, and the metal layer on the bottom of the tank and the remaining metal layer on the mask layer are naturally separated. In other cases, prior to electroplating, the method further includes: removing the metal layers on the tank walls such that they are all located on the same side of the silicon substrate, and disconnecting the metal layers on the tank bottom and the remaining metal layers on the mask layer; In the other case, the surface of the mask layer away from the silicon substrate does not obstruct the trench wall.

4. The method for preparing a solar cell according to claim 2, characterized in that, In the case where the battery substrate is an HJT battery substrate: The method of setting a mask layer includes: setting a front mask layer on the light-facing surface of the battery substrate, and / or setting a back mask layer on the back-facing surface of the battery substrate; The process of creating a groove includes: creating a groove in the front mask layer, and / or creating a groove in the back mask layer; The deposition of a metal layer includes: depositing a front metal layer on the remaining front mask layer and on the bottom of a trench on the light-facing side of the battery substrate; and / or depositing a back metal layer on the remaining back mask layer and on the bottom of a trench on the back side of the battery substrate. Electroplating includes: electroplating a metal layer on the bottom of the tank on the light-facing side of the silicon substrate and a metal layer on the remaining front mask layer, respectively, as the cathode and anode; and / or electroplating a metal layer on the bottom of the tank on the back-facing side of the silicon substrate and a metal layer on the remaining back mask layer, respectively, as the cathode and anode.

5. The method for preparing a solar cell according to claim 2, characterized in that, In the case where the battery substrate is an HBC battery substrate: The method of setting a mask layer includes: setting a back mask layer on the back surface of the battery substrate; Creating a groove includes: creating a groove in the back mask layer; Depositing a metal layer includes: depositing a back metal layer on the remaining back mask layer and on the bottom of the trench on the back surface of the battery substrate; Electroplating includes: using the metal layer on the bottom of the tank on the backlight side of the silicon substrate and the remaining metal layer on the back mask layer as the cathode and anode, respectively, for electroplating.

6. The method for preparing a solar cell according to claim 1, characterized in that, The opening of the tank is located at the end of the tank away from the silicon substrate, the bottom of the tank is opposite to the opening of the tank, and the tank wall is located between the opening and the bottom of the tank; when the battery substrate is a TOPCon battery substrate, the battery substrate includes a silicon nitride layer: The deposition of a metal layer includes: sequentially depositing an electrode metal layer and a contact barrier metal layer on the remaining mask layer and on the area on the first surface of the battery substrate where a metal electrode is to be disposed; When the surface of the mask layer away from the silicon substrate obstructs the trench wall, during the deposition of the electrode metal layer and the contact barrier metal layer: both are located on the same side of the silicon substrate, and the electrode metal layer at the bottom of the trench and the remaining electrode metal layer on the mask layer are naturally disconnected; and both are located on the same side of the silicon substrate, and the contact barrier metal layer at the bottom of the trench and the remaining contact barrier metal layer on the mask layer are naturally disconnected; after sequentially depositing the electrode metal layer and the contact barrier metal layer, the method further includes: removing both the electrode metal layer and the contact barrier metal layer at the bottom of the trench during the trenching process in the silicon nitride layer; in other cases, after sequentially depositing the electrode metal layer and the contact barrier metal layer, the method further includes: removing both the electrode metal layer and the contact barrier metal layer on the trench wall, and both the electrode metal layer and the contact barrier metal layer at the bottom of the trench during the trenching process in the silicon nitride layer; the other cases are when the surface of the mask layer away from the silicon substrate does not obstruct the trench wall. Electroplating includes: performing a first electroplating on the same side of the silicon substrate, where the electrode metal layer and contact barrier metal layer have been removed from the bottom of the tank, and the remaining contact barrier metal layer on the mask layer, respectively serving as the cathode and anode; and performing a second electroplating on the same side of the silicon substrate, where the contact barrier metal layer has been electroplated on the bottom of the tank, and the remaining electrode metal layer on the mask layer, respectively serving as the cathode and anode.

7. The method for preparing a solar cell according to claim 6, characterized in that, The method of setting a mask layer includes: setting a front mask layer on the light-facing surface of the battery substrate, and / or setting a back mask layer on the back-facing surface of the battery substrate; The process of creating a groove includes: creating a groove in the front mask layer, and / or creating a groove in the back mask layer; Sequentially depositing an electrode metal layer and a contact barrier metal layer, including: On the remaining front mask layer and on the bottom of the trench on the light-facing side of the battery substrate, a front electrode metal layer and a front contact barrier metal layer are sequentially deposited; and / or, on the remaining back mask layer and on the bottom of the trench on the back side of the battery substrate, a back electrode metal layer and a back contact barrier metal layer are sequentially deposited. The silicon nitride layer includes a front silicon nitride layer and a back silicon nitride layer; the process of removing the electrode metal layer and contact barrier metal layer on the bottom of the trench during the trenching process in the silicon nitride layer includes: when the surface of the front mask layer away from the silicon substrate blocks the trench wall on the light-facing side of the silicon substrate, removing the front electrode metal layer and the front contact barrier metal layer on the bottom of the trench on the light-facing side of the silicon substrate during the trenching process in the front silicon nitride layer; and / or, when the surface of the back mask layer away from the silicon substrate blocks the trench wall on the back light-facing side of the silicon substrate, removing the back electrode metal layer and the back contact barrier metal layer on the bottom of the trench on the back light-facing side of the silicon substrate during the trenching process in the back silicon nitride layer. The process of creating a groove in the silicon nitride layer, removing the electrode metal layer and contact barrier metal layer on the groove wall, and the electrode metal layer and contact barrier metal layer on the groove bottom, includes: removing the front electrode metal layer and front contact barrier metal layer on the groove wall on the light-facing side of the silicon substrate, and the front electrode metal layer and front contact barrier metal layer on the groove bottom on the light-facing side of the silicon substrate during the process of creating a groove in the front silicon nitride layer; and / or, removing the back electrode metal layer and back contact barrier metal layer on the groove wall on the backlight side of the silicon substrate, and the back electrode metal layer and back contact barrier metal layer on the groove bottom on the backlight side of the silicon substrate during the process of creating a groove in the back silicon nitride layer; The first electroplating includes: removing the front electrode metal layer and the front contact barrier metal layer from the bottom of the tank on the light-facing side of the silicon substrate, and using the remaining front contact barrier metal layer on the front mask layer as the cathode and anode, respectively, for the first electroplating; and / or, removing the back electrode metal layer and the back contact barrier metal layer from the bottom of the tank on the back-facing side of the silicon substrate, and using the remaining back contact barrier metal layer on the back mask layer as the cathode and anode, respectively, for the first electroplating; The second electroplating includes: using the area on the bottom of the tank on the light-facing side of the silicon substrate where the front contact barrier metal has been plated and the remaining front electrode metal layer on the front mask layer as the cathode and anode, respectively, for a second electroplating; and / or using the area on the bottom of the tank on the back-facing side of the silicon substrate where the back contact barrier metal has been plated and the remaining back electrode metal layer on the back mask layer as the cathode and anode, respectively, for a second electroplating.

8. The method for preparing a solar cell according to any one of claims 1-7, characterized in that, After the metal electrodes of the battery substrate are formed: If there is residual metal on the remaining mask layer, the method further includes: removing the residual metal from the remaining mask layer; If the mask layer is a non-anti-reflective film layer, the method further includes: removing the remaining mask layer.

9. The method for preparing a solar cell according to any one of claims 1-7, characterized in that, The material of the mask layer is selected from: dielectric materials; And / or, the thickness of the mask layer is 1-50 μm; the thickness of the mask layer is: the dimension of the mask layer in the direction in which the mask layer is disposed on the battery substrate; And / or, the mask layer includes at least one of spin coating, roller coating, spray coating, and dip coating; And / or, the groove includes at least one of: exposure development, mechanical scribing, and laser scribing; And / or, the deposited metal layer includes at least one of: vapor deposition, sputtering, and electroplating; And / or, the material of the metal layer is selected from at least one of nickel, copper, silver, and tin; And / or, the thickness of the metal layer is 100-300 nm; When the material of the metal layer is selected from copper, the electroplating solution includes copper sulfate solution and electroplating additives during the electroplating process.

10. The method for preparing a solar cell according to any one of claims 1-7, characterized in that, The material of the mask layer is selected from one of the following: photoresist, ink, paraffin, organic thin film, and metal oxide.

11. The method for preparing a solar cell according to any one of claims 3, 6, and 7, characterized in that, When the surface of the mask layer away from the silicon substrate obstructs the trench wall, the shape of the trench includes at least one of the following: a frustum, a truncated cone, and a bowl-shaped structure.

12. The method for preparing a solar cell according to claim 8, characterized in that, When the material of the mask layer is photoresist, removing the remaining residual metal on the remaining mask layer includes: using a first alkaline solution to remove the remaining residual metal on the remaining mask layer; When the material of the mask layer is photoresist, removing the remaining mask layer includes: removing the remaining mask layer using a second alkaline solution.

13. The method for preparing a solar cell according to claim 12, characterized in that, The first alkaline solution is obtained by mixing ammonia water with a concentration of 1.8-2.4 mol / L and hydrogen peroxide with a concentration of 0.55-0.66 mol / L; The second alkaline solution comprises: a 0.1-0.3 mol / L sodium hydroxide solution.

14. The method for preparing a solar cell according to any one of claims 1-7, characterized in that, When the mask layer is made of photoresist, the groove is formed by: laser grooving with a laser wavelength of 350nm-460nm and a laser energy of 50-70mJ / cm². 2 .

15. The method for preparing a solar cell according to claim 6 or 7, characterized in that, The material of the contact barrier metal layer includes nickel, and / or the material of the electrode metal layer includes copper.

16. A solar cell, characterized in that, The solar cell is prepared by the method for preparing a solar cell according to any one of claims 1-15.

Images