Metal electrode, preparation method thereof and crystalline silicon solar cell

Abstract

The invention discloses a metal electrode, a preparation method thereof and a crystalline silicon solar cell. According to the preparation method of the metal electrode, a protective layer or a patterned mask is prepared before electroplating, so that the cell is prevented from being in direct contact with electroplating liquid, damage to the cell in the preparation process is reduced, and the cell is protected; the Ni seed layer is prepared by adopting indirect PVD (Physical Vapor Deposition), so that the adhesive force of electroplated alloy metal is improved, the metal is prevented from falling off, the serious damage is reduced, and the performance and the reliability of the battery are improved; alloy metals such as copper, nickel and tin are adopted to replace precious metal silver, so that the preparation cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of crystalline silicon solar cells, and in particular to a metal electrode and a preparation method thereof, and a crystalline silicon solar cell. Background Art

[0002] Metallization is an important process in manufacturing heterogeneous crystalline silicon solar cells, which is used to form metal grid electrodes on the cell sheet, and can be achieved by screen printing or electroplating. However, the existing silver paste uses a large amount of silver paste and is expensive, and the screen printing process will cause a waste of paste. It is difficult to optimize the grid shaping, the stability is poor, and it is difficult to ensure the efficiency stability; and the traditional electroplating method is to directly electroplate metal on the oxide layer, which has poor adhesion and is easy to fall off, and directly immersing the solar cell in the plating solution will cause serious damage to the cell. Summary of the invention

[0003] The main purpose of the present invention is to provide a method for preparing a metal electrode, aiming to solve the problem that the traditional screen printing and electroplating methods for preparing metal electrodes lead to serious damage to the battery.

[0004] In order to achieve the above object, the present invention provides a method for preparing a metal electrode, which includes two preparation methods with the same principle: Method 1: Preparation of Ni seed layer: sputtering a selective seed layer of Ni on glass; Laser-heated sputtering: Using a patterned laser to heat from the glass side, the Ni seed layer is sputtered and deposited on both sides of the battery; Preparation of protective layer: Sputtering a layer of SiO on both sides of the cell with the Ni seed layer 2 / SiN x Protective layer; Laser / thermal annealing treatment: The SiO 2 / SiN x The protective layer penetrates to expose the Ni seed layer; Electroplating: Alloy metal is electroplated on both sides of the battery to prepare metal electrodes.

[0005] Method 2: Making a mask: attaching a patterned mask to both sides of the battery to form a designated gate electrode opening; Preparation of Ni seed layer: sputtering a selective seed layer of Ni on glass; Laser heating sputtering: The laser that sets the grid line spacing is heated from the glass side, and the Ni seed layer is sputtered and deposited in the laser openings on both sides of the battery; Electroplating: Electroplating alloy metals on both sides of the battery to prepare metal electrodes; Mask removal: Melt the mask on the battery with an ester-soluble solution, or penetrate it with a laser.

[0006] In one embodiment, the SiO 2 / SiN x The thickness of the protective layer is 50-500 nm.

[0007] In one embodiment, the thickness of the Ni seed layer is 1-1000 nm.

[0008] In one embodiment, the specific steps of electroplating the alloy metal on both sides of the battery are: First, electroplate the metal copper and nickel; Then electroplate metallic tin.

[0009] The present invention also provides a metal electrode, which is obtained by the above-mentioned method for preparing the metal electrode.

[0010] The present invention further provides a crystalline silicon solar cell, which comprises a cell and the above-mentioned metal electrode.

[0011] The technical solution of the present invention prepares a protective layer or a patterned mask before electroplating to avoid direct contact between the battery and the electroplating solution, thereby reducing damage to the battery during the preparation process to protect the battery; and adopts indirect PVD to prepare the Ni seed layer to improve the adhesion of the electroplated alloy metal to avoid metal shedding, thereby reducing serious damage to the battery, thereby improving the performance and reliability of the battery; and adopts alloy metals such as copper, nickel and tin instead of precious metal silver to reduce the preparation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the process of method 1 of the method for preparing a metal electrode of the present invention; Figure 2 A schematic flow chart of method 2 of the method for preparing a metal electrode of the present invention; Figure 3 Schematic diagram of the steps of method 1 of the preparation method of the metal electrode of the present invention; Figure 4 Schematic diagram of the steps of method 2 of the preparation method of the metal electrode of the present invention; In the figure: 1-transparent glass, 2-Ni selective seed layer, 3-grid spacing, 4-patterning laser, 5-battery, 6-Ni selective seed layer deposited on the battery, 7-SiO 2 / SiN x Protective layer, 8-metal electrode, 9-ester soluble organic solvent, 10-mask. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0014] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0016] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use, or are directions or positional relationships commonly understood by those skilled in the art. These directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0017] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0018] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms such as "setting" and "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0019] Among the existing methods for preparing metal electrodes, the screen printing method uses a large amount of silver paste, is expensive, and causes waste of paste during the process. It is difficult to optimize the shaping of the grid lines, has poor stability, and is difficult to ensure efficiency stability. The traditional electroplating method directly electroplates metal on the oxide layer, which has poor adhesion and is easy to fall off. Moreover, directly immersing the battery in the electroplating solution will cause serious damage to the battery. Therefore, the present invention proposes a method for preparing metal electrodes, which uses low-cost alloy metals such as copper and nickel instead of precious metal silver to prepare metal electrodes by electroplating, thereby reducing damage to the battery and improving the performance and reliability of crystalline silicon solar cells. The specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0020] like Figure 1-4 As shown, the method for preparing the metal electrode comprises the following steps: Preparation of Ni seed layer: sputtering a selective seed layer of Ni on glass; Laser heating sputtering: using a patterned laser to heat from the glass side, the Ni seed layer is sputtered and deposited on both sides of the battery 5; Preparation of protective layer: Sputtering a layer of SiO on both sides of the battery 5 with the Ni seed layer 2 / SiN x Protective layer 7; Laser / thermal annealing treatment: The SiO 2 / SiN x The protective layer 7 penetrates, exposing the Ni seed layer; Electroplating: Electroplating the alloy metal on both sides of the battery 5 to prepare the metal electrode 8.

[0021] In one embodiment, the SiO 2 / SiN x The thickness of the protective layer 7 is 50-500 nm.

[0022] In one embodiment, the method for preparing the metal electrode further comprises the following steps with the same principle: Making a mask plate 10: attaching a patterned mask to both sides of the battery 5 to form a designated gate electrode opening; Preparation of Ni seed layer: sputtering a selective seed layer of Ni on glass; Laser heating sputtering: the laser for setting the grid line spacing 3 is heated from the glass side, and the Ni seed layer is sputtered and deposited in the laser openings on both sides of the battery 5; Electroplating: Electroplating the alloy metal on both sides of the battery 5 to prepare the metal electrode 8; Removing the mask: The mask on the battery 5 is melted with an ester-soluble solution, or penetrated with a laser.

[0023] In one embodiment, the thickness of the Ni seed layer is 1-1000 nm.

[0024] In one embodiment, the specific steps of electroplating the alloy metal on both sides of the battery 5 are: First, electroplate the metal copper and nickel; Then electroplate metallic tin.

[0025] In this embodiment, there are two methods for preparing the metal electrode. Method 1: PVD (Physical Vapor Deposition) prepares a Ni seed layer, a Ni selective seed layer 2 is prepared on both sides of the heterojunction battery substrate, and a SiO 2 / SiN x Protective layer 7, laser / thermal annealing, electroplating metal electrode 8, Figure 3 The preparation process of the metal electrode in method 1 is as follows: Figure 3 (h) shows method 1 for preparing a crystalline silicon solar cell with a metal electrode 8; method 2: preparing a mask plate 10, preparing a Ni seed layer by PVD, preparing a Ni selective seed layer 2 on both sides of the crystalline silicon solar cell substrate, laser heating sputtering, electroplating a metal electrode 8, and removing the mask layer. Figure 4 The preparation process of the metal electrode prepared by method 2 is as follows: Figure 4 (g) shows a crystalline silicon solar cell with a metal electrode 8 prepared by method 2.

[0026] In this embodiment, a protective layer is prepared before electroplating the alloy metal to prevent the battery 5 from contacting the electroplating solution, and the contact area between the metal electrode 8 and the TCO layer (Transparent Conductive Oxide Layer) of the battery 5 is reduced, thereby reducing the contact resistance between the battery 5 and the metal electrode 8 and increasing the effective utilization area of ​​the crystalline silicon solar cell; wherein, the protective layer is prepared by physical vapor deposition, including but not limited to sputtering, to form a uniform protective layer on the surface of both sides of the battery 5, and the protective layer is directly covered on the selective seed layer.

[0027] In this embodiment, the patterned laser 4 is a laser set with a grid line spacing 3 to accurately deposit the Ni selective seed layer 2 from the glass substrate onto the crystalline silicon solar cell to achieve a local heating effect and obtain a Ni seed layer with a fixed grid line spacing 3; this method does not require the use of the seed layer preparation of the entire surface area of ​​the battery 5, and the Ni seed layer prepared by laser sputtering and the protective layer prepared by sputtering can improve the adhesion of the subsequent electroplated alloy metal to avoid metal shedding.

[0028] In this embodiment, SiO 2 / SiN xThe thickness of the protective layer 7 is 50-500 nm, so that the battery 5 precursor cannot conduct electricity. It is necessary to peel off the protective layer on the Ni seed layer, that is, penetrate it by laser to expose the Ni seed layer on its surface. It can be understood that the protective layer on the selective seed layer is penetrated by the patterning laser 4 or thermal annealing method, while the part directly covering the battery 5 is still retained on it, and only the selective seed layer is exposed to facilitate metal plating; wherein, the thermal annealing can use at least one of air, nitrogen, argon, and hydrogen gas, and the annealing temperature range is 120 ℃-200 ℃.

[0029] In this embodiment, Ni, Cu, and Sn metals are prepared in sequence on the Ni seed layer by electroplating, which serve as the metal conductive layer and the anti-oxidation layer respectively; Ni, Cu, and Sn metal electrodes 8 are prepared by electrochemistry. Specifically, Ni is plated using a nickel sulfate solution, the electroplating voltage is 1-50 V, and the electroplating current is 1-5 A / cm 2 ; Cu plating uses copper sulfate solution, the electroplating voltage is 1-50 V, and the electroplating current is 1-5 A / cm 2 Sn plating uses tin sulfamate solution, the plating voltage is 1-10 V, and the plating current is 0.1-5 A / cm 2 , preparing the metal electrode 8 by electroplating method to obtain a narrower line width, improve the conversion efficiency of the battery 5, and reduce the consumption of silver paste; In this example, the patterned mask prepared on the battery 5 in the second method can protect the battery 5 during the electroplating process.

[0030] The preparation method of the metal electrode of the present invention prepares a protective layer or a patterned mask before electroplating to prevent the battery 5 from directly contacting the electroplating solution, thereby reducing damage to the battery 5 during the preparation process and protecting the battery 5; and adopts indirect PVD to prepare the Ni seed layer to improve the adhesion of the electroplated alloy metal to avoid metal shedding, thereby reducing serious damage to the battery 5, thereby improving the performance and reliability of the battery 5; and adopts alloy metals such as copper, nickel and tin instead of precious metal silver to reduce the preparation cost.

[0031] The present invention also proposes a metal electrode 8, which is obtained by the above-mentioned method for preparing the metal electrode; the specific preparation method of the metal electrode 8 refers to the above-mentioned embodiment. Since the metal electrode 8 adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0032] The present invention further provides a crystalline silicon solar cell, which includes a cell 5 and the above-mentioned metal electrode 8 .

[0033] In summary, the preparation method of the metal electrode of the present invention adopts the electroplating method to prepare the metal electrode 8, which can obtain a narrower line width, improve the conversion efficiency of the battery 5, and reduce the silver paste consumption; the protective layer prepared before electroplating the metal electrode 8 can not only prevent the battery 5 from contacting with the plating solution, but also reduce the contact area between the metal electrode 8 and the TCO layer of the battery 5, thereby effectively reducing the contact resistance between the battery 5 and the metal electrode 8, and increasing the effective utilization area of ​​the crystalline silicon solar cell; laser sputtering to prepare the Ni seed layer does not require the use of the seed layer of the entire surface area of ​​the battery 5. The laser sputtering Ni seed layer and the sputtering protective layer can improve the adhesion of the subsequent electroplated metal electrode 8 and avoid the metal electrode 8 from being de-gated; this electroplating method for preparing the metal electrode of the crystalline silicon solar cell reduces the damage to the battery 5 caused by the electrode preparation process, improves the reliability of the battery 5, and reduces the waste of slurry.

[0034] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a metal electrode, characterized in that: The method for preparing the metal electrode comprises the following steps: Preparation of Ni seed layer: sputtering a selective seed layer of Ni on glass; Laser-heated sputtering: Using a patterned laser to heat from the glass side, the Ni seed layer is sputtered and deposited on both sides of the battery; Preparation of protective layer: Sputtering a layer of SiO2 / SiN on both sides of the cell with the Ni seed layer x Protective layer; Laser / thermal annealing treatment: SiO2 / SiN on the Ni seed layer is annealed by laser heating or laser annealing. x The protective layer penetrates to expose the Ni seed layer; Electroplating: Alloy metal is electroplated on both sides of the battery to prepare metal electrodes.

2. The method for preparing a metal electrode according to claim 1, characterized in that: The SiO2 / SiN x The thickness of the protective layer is 50-500 nm.

3. The method for preparing a metal electrode according to claim 1, characterized in that: The method for preparing the metal electrode also includes the following steps with the same principle: Making a mask: attaching a patterned mask to both sides of the battery to form a designated gate electrode opening; Preparation of Ni seed layer: sputtering a selective seed layer of Ni on glass; Laser heating sputtering: The laser that sets the grid line spacing is heated from the glass side, and the Ni seed layer is sputtered and deposited in the laser openings on both sides of the battery; Electroplating: Electroplating alloy metals on both sides of the battery to prepare metal electrodes; Mask removal: Melt the mask on the battery with an ester-soluble solution, or penetrate it with a laser.

4. The method for preparing a metal electrode according to any one of claims 1 and 3, characterized in that: The thickness of the Ni seed layer is 1-1000 nm.

5. The method for preparing a metal electrode according to any one of claims 1 and 3, characterized in that: The specific steps of electroplating the alloy metal on both sides of the battery are: First, electroplate the metal copper and nickel; Then electroplate metallic tin.

6. A metal electrode, characterized in that: The metal electrode is obtained by the preparation method of the metal electrode according to any one of claims 1 to 5.

7. A crystalline silicon solar cell, characterized in that: The crystalline silicon solar cell comprises a cell and the metal electrode as claimed in claim 6.

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