Double-sided metallized solar cell, preparation method thereof, and movable anode device

Abstract

The present invention provides a double-sided metallized solar cell, a preparation method thereof, and a movable anode device, relating to the technical field of solar cells. The preparation method of the double-sided metallized solar cell comprises the following steps: laser-cutting a silicon substrate of the solar cell, roughening the back of the cut silicon substrate of the solar cell with a roughening agent; then sequentially performing double-sided nickel plating, a first double-sided copper plating, annealing, a second double-sided copper plating, and double-sided tin plating on the silicon substrate of the solar cell to obtain a double-sided metallized solar cell. The preparation method of the double-sided metallized solar cell provided by the present invention can improve the bonding strength of the grid lines on the back of the cell. At the same time, after preparing a nickel seed layer, the preparation method further electroplates a thin copper layer on the surface of the nickel layer, and then performs heat treatment, which can significantly inhibit the oxidation of the nickel layer and form a nickel-silicon alloy. After the heat treatment, no significant thermal expansion occurs, and oxidation of the nickel layer surface is inhibited, thereby avoiding the nickel removal step.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a double-sided metallized solar cell, a preparation method thereof, and a movable anode device. Background Art

[0002] To reduce solar cell costs and improve cell efficiency, electroplating is commonly used to produce the metal electrodes of silicon solar cells. Electroplating generally uses a plating solution containing metal ions instead of silver paste, thereby reducing the production cost of silicon solar cells and making the product more competitive. Electroplating technology usually begins by preparing a seed layer at the slot location of the cell to prevent copper diffusion, then electroplating copper as a conductive layer, and finally electroplating a protective layer, ultimately resulting in a double-sided electroplated solar cell.

[0003] In order to reduce costs, some researchers have used a thin silver layer printed by screen printing as a seed layer and then electroplated copper as the main conductive layer, but this method does not have a significant advantage in reducing the cost of silver. It is further proposed to use an electroplating process to prepare the front and back electrodes. Usually, a nickel layer is first prepared on both sides as a seed layer, and then copper is electroplated on both sides as a conductive layer. Finally, tin is electroplated on both sides as a protective layer, and finally a double-sided electroplated solar cell is obtained. Although this method completely replaces the use of silver, it may cause uneven thickness of the nickel plating layer due to the purity of the plating solution and uneven current distribution, which in turn affects subsequent electroplating. At the same time, the internal stress of the nickel layer is large, and there is a problem of poor bonding between the plating layer and the silicon substrate. It should be noted that before the electroplating process begins, it needs to be patterned by laser grooving. When the front is grooved, since the front is a pyramid structure, the pyramid structure is still retained after grooving, which can form a stable contact with the electroplating layer and has a high bonding force. However, the back does not have a pyramid structure. Under the same parameters, the bonding force of the back after grooving is not as good as that of the front. In the past, the commonly used technology was to nickel-plated and then heat-treated to form a nickel-silicon alloy to enhance the bonding strength. However, during the heat treatment process, an oxide layer would form on the surface nickel, which needed to be removed before subsequent processes could be carried out, which greatly increased the complexity of the process.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] One of the purposes of the present invention is to provide a method for preparing a double-sided metallized solar cell. The method for preparing a double-sided metallized solar cell comprises the following steps: laser opening the film of the solar cell silicon substrate to form a groove in a preset grid line area, and roughening the back of the solar cell silicon substrate after opening the film with a roughening agent; then the solar cell silicon substrate is subjected to double-sided nickel plating, a first double-sided copper plating, annealing, a second double-sided copper plating, and double-sided tin plating in sequence to obtain a double-sided metallized solar cell. The method for preparing a double-sided metallized solar cell provided by the present invention can improve the bonding strength between the grid line and the cell substrate, and at the same time, through the first double-sided copper plating process, a nickel-silicon alloy can be effectively formed to improve the bonding strength, while avoiding nickel surface oxidation. No additional nickel removal process is required, and the overall process is simpler and faster.

[0006] A second object of the present invention is to provide a double-sided metallized solar cell manufactured using the above-mentioned method for manufacturing a double-sided metallized solar cell. The double-sided metallized solar cell has a strong grid line bonding force.

[0007] A third objective of the present invention is to provide a movable anode device. The movable anode device comprises a plating anode and a movable assembly. The plating anode is positioned beneath the silicon substrate of a solar cell to be plated with metal. The end of the plating anode is connected to the movable assembly, and the movable assembly is capable of moving the plating anode to nickel-plate the silicon substrate of the solar cell. Using this device for metal plating ensures uniform light exposure during the cell plating process, preventing excessive local current flow and promoting uniform plating grid lines.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0009] In a first aspect, the present invention provides a method for preparing a double-sided metallized solar cell, the method comprising the following steps:

[0010] Laser-cutting the silicon substrate of the solar cell to form grooves in the preset grid line area, and roughening the back surface of the silicon substrate of the solar cell after cutting with a roughening agent;

[0011] Then, the solar cell silicon substrate is subjected to double-sided nickel plating, first double-sided copper plating, annealing, second double-sided copper plating and double-sided tin plating in sequence to obtain a double-sided metallized solar cell.

[0012] In the present invention, the preparation method of the double-sided metallized solar cell can improve the bonding strength of the grid lines on the back side of the cell. By roughening the groove position on the back side, the bonding strength of the nickel seed layer and the silicon substrate is better, resulting in better bonding strength of the entire nickel-copper-tin plating layer and the silicon substrate, and the welding tensile force also meets the requirements. It can also further reduce the thickness of the nickel layer and reduce costs. At the same time, after preparing the nickel seed layer, the preparation method electroplates copper on the surface of the nickel layer and then performs heat treatment, which can significantly inhibit the oxidation of the nickel layer and form a nickel-silicon alloy. After the heat treatment, no obvious thermal expansion will occur and the oxidation of the nickel layer surface will be inhibited, thereby avoiding the nickel removal step.

[0013] Preferably, before laser opening the silicon substrate of the solar cell, a mask layer is prepared on the back side of the silicon substrate of the solar cell;

[0014] Preferably, the solar cell substrate comprises a silicon substrate and a coating layer deposited on the surface of the silicon substrate, and the mask layer is deposited on the surface of the coating layer;

[0015] Preferably, the coating layer is a silicon nitride film, and the thickness of the silicon nitride film is 50-100 nm;

[0016] Preferably, the thickness of the mask layer is 15-50 nm, for example, 10 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, etc.;

[0017] In the present invention, the mask layer can protect the non-grooving position from being damaged during roughening.

[0018] Preferably, the groove has a width of 5-50 μm, for example, 5 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc., and a depth of 50-100 nm, for example, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, etc.;

[0019] In the present invention, the grooves on the front and back sides of the battery silicon substrate are patterned grooves. The patterned grooves may include one or both of coarse grooves and fine grooves. The number of coarse grooves and fine grooves in the patterned grooves may be adjusted according to actual needs.

[0020] Preferably, the roughening agent is one of a KOH solution and a TMAH solution;

[0021] Preferably, the concentration of the KOH solution is 20-30%, for example, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, etc., and the concentration of the TMAH solution is 20-25%, for example, 20%, 21%, 22%, 23%, 24%, 25%, etc.;

[0022] Preferably, the roughening time is 15-30s, for example, it can be 15s, 16s, 17s, 18s, 19s, 20s, 21s, 22s, 23s, 24s, 25s, 26s, 27s, 28s, 29s, 30s, etc.

[0023] Preferably, during the roughening process, the mask layer in the non-preset gate line region is removed.

[0024] Preferably, after forming the grooves on the back side of the solar cell silicon substrate and before roughening, the mask layer in the film opening area on the back side of the solar cell silicon substrate is removed to expose the silicon substrate.

[0025] Preferably, after roughening the solar cell silicon substrate and before double-sided nickel plating, the roughened solar cell silicon substrate is cleaned;

[0026] Preferably, an acid cleaning agent is used to clean the solar cell silicon substrate;

[0027] Preferably, the pickling agent is a hydrofluoric acid solution;

[0028] Preferably, the amount of hydrofluoric acid added to the hydrofluoric acid solution is 10-20 mL / L, for example, 11 mL / L, 12 mL / L, 13 mL / L, 14 mL / L, 15 mL / L, 16 mL / L, 17 mL / L, 18 mL / L, 19 mL / L, 20 mL / L, etc.;

[0029] Preferably, the temperature of the pickling agent is 25-38°C, for example, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, etc.

[0030] Preferably, the pickling time is 5-50s, for example, 5s, 10s, 15s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, etc.

[0031] Preferably, the solar cell silicon substrate is pickled, electroplated with metal nickel, and then blown dry;

[0032] Preferably, the drying temperature is 15-20°C, for example, 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, etc.

[0033] Preferably, the copper plating layer thickness of the first double-sided copper plating is 0.5-1 μm;

[0034] In the present invention, the copper plating layer of the first double-sided copper plating is thin copper. The thin copper can prevent surface oxidation during nickel annealing and will not hinder the formation of nickel-silicon alloy. There is no need to remove nickel separately. Even if the copper surface is oxidized, it is very easy to remove. Compared with nickel removal, it is faster and simpler and does not affect subsequent processes.

[0035] Preferably, the thickness of the copper plating layer of the second double-sided copper plating is 9-12um, for example, 9um, 10um, 11um, 12um, etc.;

[0036] Preferably, the thickness of the double-sided tinned layer is 1-2 μm, for example, 1 μm, 1.5 μm, 2 μm, etc.

[0037] Preferably, after annealing and before the second double-sided copper plating, the double-sided copper-plated solar cell is pickled;

[0038] Preferably, the pickling is carried out using a sulfuric acid solution;

[0039] Preferably, the concentration of the sulfuric acid solution is 10-15%, for example, it can be 10%, 11%, 12%, 13%, 14%, 15%, etc.;

[0040] Preferably, the pickling time is 10-20s, 10s, 11s, 12s, 13s, 15s, 16s, 17s, 18s, 19s, 20s, etc.

[0041] In a second aspect, the present invention provides a double-sided metallized solar cell prepared by the method for preparing a double-sided metallized solar cell.

[0042] The double-sided metallized solar cell prepared by the double-sided metallized solar cell preparation method has strong grid line bonding force.

[0043] In a third aspect, the present invention provides a movable anode device comprising an electroplating anode and a movable assembly;

[0044] The electroplating anode is arranged below the silicon substrate of the solar cell to be plated with metal in the method for preparing the double-sided metallized solar cell. The end of the electroplating anode is connected to the moving component, and the moving component can drive the electroplating anode to move to electroplate metal on the silicon substrate of the solar cell.

[0045] In the present invention, the movable anode device can effectively avoid local continuous shading and local continuous resistance difference, which is conducive to achieving uniform electroplating of the grid line.

[0046] Preferably, the movable anode device comprises two movable components, the two movable components being a first movable component and a second movable component;

[0047] The first moving component is connected to one end of the electroplating anode, and the second moving component is connected to the other end of the electroplating anode;

[0048] Preferably, the electroplating anode includes one or more of an iridium-based titanium-based metal oxide anode, a ruthenium-based titanium-based metal oxide anode, and a lead dioxide-based titanium-based metal oxide anode;

[0049] Preferably, the electroplating anode is in the shape of a strip;

[0050] Preferably, the moving speed of the electroplating anode is 30-50 cm / min.

[0051] Preferably, the first moving assembly includes a first moving chain and a first connecting block;

[0052] The first connecting block is connected to one end of the electroplating anode, and the first movable chain is connected to the first connecting block, and the first movable chain is movable to drive the first connecting block to move;

[0053] The second moving assembly includes a second moving chain and a second connecting block;

[0054] The second connecting block is connected to one end of the electroplating anode away from the first connecting block, and the second movable chain is connected to the second connecting block. The second movable chain is movable to drive the second connecting block to move.

[0055] Preferably, the movable anode device further comprises an electroplating tank, a suction cup and a light source component;

[0056] The electroplating tank is used to contain the electroplating solution, and the electroplating anode is placed in the electroplating tank;

[0057] The suction cup is arranged above the electroplating tank and is used to absorb the solar cell silicon substrate to be plated with metal;

[0058] The light source component is arranged below the electroplating tank and is used for irradiating light into the electroplating tank.

[0059] Furthermore, the method for preparing a double-sided metallized solar cell comprises the following steps:

[0060] (1) Providing a solar cell silicon substrate;

[0061] (2) preparing a mask layer on the back side of the silicon substrate of the solar cell;

[0062] (3) forming a patterned groove in a preset gate line area on the back side of the solar cell silicon substrate by laser film opening, and simultaneously removing the back mask layer in the film opening area to expose the silicon substrate;

[0063] (4) forming a patterned groove in a preset grid line area on the front surface of the solar cell silicon substrate by laser film opening;

[0064] (5) Adding an appropriate amount of KOH or TMAH solution to the pure water solution, circulating and stirring evenly to prepare a roughening agent; first, using a suction cup to adsorb the front side of the solar cell silicon substrate, and floating the back side on the roughening agent, while roughening, using KOH or TMAH solution to remove the mask layer, that is, KOH or TMAH solution can react with the mold opening area to achieve the purpose of roughening, and can also react with the mask layer to remove the mask layer;

[0065] (6) adding an appropriate amount of hydrofluoric acid to the pure water solution, stirring it in a cycle to prepare an acid wash agent; first, using a conductive suction cup to absorb the front side of the solar cell silicon substrate after film opening, and then cleaning the roughened solar cell sheet in the acid wash agent. After cleaning, the suction cup is moved to the nickel electroplating tank position, and the back side is floated in the nickel electroplating solution for a period of time. At the same time, the light source and the movable anode device are turned on to start electroplating. After the electroplating is completed, the back side of the silicon substrate is cleaned and dried, and the front side of the silicon substrate is turned over and electroplated according to the above method. After both sides are plated, a double-sided nickel-plated solar cell silicon substrate is obtained;

[0066] (7) The double-sided nickel-plated silicon substrate of the solar cell is subjected to double-sided thin copper plating;

[0067] (8) performing heat treatment annealing on the double-sided thin copper solar cell through a sintering furnace;

[0068] (9) acid washing the annealed double-sided thin copper solar cell;

[0069] (10) Electroplating normal copper and tin on both sides of the pickled double-sided thin copper solar cell in sequence to obtain a finished metallized solar cell.

[0070] Compared with the prior art, the present invention has the following beneficial effects:

[0071] The method for preparing a double-sided metallized solar cell provided by the present invention can improve the bonding strength of the grid lines on the back side of the cell, roughen the film opening position to increase the bonding strength with the grid lines, and roughen the grooves on the back side, which can further reduce the thickness of the nickel layer and reduce costs. At the same time, after preparing the nickel seed layer, the preparation method electroplates copper on the surface of the nickel layer and then performs heat treatment, which can significantly inhibit the oxidation of the nickel layer and form a nickel-silicon alloy. After the heat treatment, no obvious thermal expansion will occur and the oxidation of the nickel layer surface will be inhibited, thereby avoiding the nickel removal step.

[0072] The movable anode device provided by the present invention can make the cell receive light uniformly during the electroplating process, avoid excessive local current, and promote the uniformity of the electroplating grid lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0074] Figure 1 A top view of a movable anode device provided in an embodiment of the present invention.

[0075] Icon: 100-electroplating anode; 200-first moving component; 210-first moving chain; 220-first connecting block; 300-second moving component; 310-second moving chain; 320-second connecting block; 400-electroplating tank; 500-suction cup; 600-light source. DETAILED DESCRIPTION

[0076] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear; however, in the event of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, the use of "or" means "and / or" unless otherwise stated. In addition, the use of the term "including" and other forms is non-limiting.

[0077] Generally, the nomenclature used in conjunction with cell and tissue culture, molecular biology, immunology, microbiology, genetics, and protein and nucleic acid chemistry and hybridization as described herein and its technology are those well-known and commonly used in this area.Unless otherwise indicated, the methods and techniques of the present invention are generally according to those well-known in the art, and are carried out as described in various general and more specific references, which are cited and discussed throughout this specification.Enzymatic reactions and purification techniques are carried out according to the manufacturer's specifications, as commonly achieved in this area, or as described herein.The nomenclature used in conjunction with analytical chemistry, synthetic organic chemistry, and medical and pharmaceutical chemistry as described herein and its laboratory procedures and technology are those well-known and commonly used in this area.

[0078] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0079] like Figure 1 As shown, the present invention provides a movable anode device, including an electroplating anode 100 and a movable component; the electroplating anode 100 is arranged below the silicon substrate of a solar cell to be plated with metal in a method for preparing a double-sided metallized solar cell, and the end of the electroplating anode 100 is connected to the movable component, and the movable component can drive the electroplating anode 100 to move to electroplate metal on the silicon substrate of the solar cell.

[0080] At present, in the process of light-induced electroplating, the most common device is that the light source is at the bottom, the electroplating tank 400 is above the light source, the anode is placed at the bottom of the electroplating tank 400, and the suction cup 500 is used to adsorb the battery cell and float it on the surface of the plating solution for electroplating. However, since the resistance of the anode in the vertical direction between the battery cell is the smallest and it will block part of the light source, this will lead to uneven height of the electroplating grid line, which has an adverse effect on subsequent electroplating or component welding. Therefore, the movable anode device provided by the present invention can make the battery cell receive light evenly during the electroplating process by setting a movable electroplating anode 100, will not make the local current too large, and promote the uniformity of the electroplating grid line.

[0081] Regarding the shape and structure of the mobile components, in detail:

[0082] The movable anode device includes two movable components, namely a first movable component 200 and a second movable component 300 .

[0083] The first moving assembly 200 is connected to one end of the electroplating anode 100, and the second moving assembly 300 is connected to the other end of the electroplating anode 100. The first moving assembly 200 includes a first moving chain 210 and a first connecting block 220. The first connecting block 220 is connected to one end of the electroplating anode 100 and is connected to the first connecting block 220. The first moving chain 210 is movable to drive the first connecting block 220 to move. The second moving assembly 300 includes a second moving chain 310 and a second connecting block 320. The second connecting block 320 is connected to the end of the electroplating anode 100 away from the first connecting block 220. The second moving chain 310 is connected to the second connecting block 320. The second moving chain 310 is movable to drive the second connecting block 320 to move.

[0084] Specifically, the first connecting block 220 and the second connecting block 320 are respectively connected to the two ends of the electroplating anode 100. The first moving chain 210 is connected to the output end of the motor. The motor drives the first moving chain 210 to move, thereby driving the first connecting block 220 to connect, thereby driving the electroplating anode 100 to move. Similarly, the second moving chain 310 is connected to the output end of the motor. The motor drives the second moving chain 310 to move, thereby driving the second connecting block 320 to connect, thereby driving the electroplating anode 100 to move. The motors connected to the first moving chain 210 and the second moving chain 310 are existing technologies. They can drive the moving chains to move and ultimately drive the electroplating anode 100 to move. Their structure will not be described in detail here.

[0085] In an optional embodiment, the electroplating anode 100 includes one or more of an iridium-based titanium-based metal oxide anode, a ruthenium-based titanium-based metal oxide anode, and a lead dioxide-based titanium-based metal oxide anode;

[0086] In an optional embodiment, in order to minimize the light-shielding area, the electroplating anode 100 is in a strip shape;

[0087] In an optional embodiment, the moving speed of the electroplating anode 100 is 30-50 cm / min.

[0088] The movable anode device provided by the present invention also includes an electroplating tank 400, a suction cup 500 and a light source component. The electroplating tank 400 is used to contain the electroplating liquid. The electroplating anode 100 is placed in the electroplating tank 400. The suction cup 500 is arranged above the electroplating tank 400 and is used to adsorb the solar cell silicon substrate to be plated with metal. The light source component is arranged below the electroplating tank 400 and is used to irradiate the light source 600 into the electroplating tank 400.

[0089] Specifically, the light source is a light source used in the light-induced electroplating process. The electroplating anode 100 is placed in the electroplating tank 400. The moving range of the electroplating anode 100 matches the size of the electroplating tank 400. For example, Figure 1 As shown, the electroplating anode 100 is arranged along the length direction of the electroplating tank 400 , and there is at least one electroplating anode 100 . The moving chain moves, and eventually drives the electroplating anode 100 to move along the width direction of the electroplating tank 400 .

[0090] The method for using the movable anode device provided by the present invention is as follows:

[0091] First, use a conductive suction cup 500 to absorb the front side of the solar cell silicon substrate after film opening, and clean the roughened solar cell in an acid pickling agent. After cleaning, the suction cup 500 is moved to the nickel electroplating tank 400 position, and the back side floats in the nickel electroplating solution for a period of time. At the same time, turn on the light source, and make the two movable chains in the movable anode device drive the electroplating anode 100 to move, and start electroplating. After the electroplating is completed, clean and dry the back side of the silicon substrate, turn it over and electroplate the front side of the silicon substrate according to the above method. After both sides are plated, a solar cell silicon substrate with double-sided nickel plating is obtained.

[0092] It should be noted that the above uses nickel plating as an example to illustrate the use of the movable anode device. The movable anode device can also be applied to other metal electroplating processes.

[0093] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples were prepared according to existing methods or directly purchased from the market.

[0094] Example 1

[0095] This embodiment provides a method for preparing a double-sided metallized solar cell, comprising the following steps:

[0096] (1) Providing a solar cell silicon substrate, the solar cell substrate comprising a silicon substrate and a coating layer deposited on the surface of the silicon substrate, the coating layer being a silicon nitride film, and the thickness of the silicon nitride film being 50 nm;

[0097] (2) preparing a mask layer on the back coating layer of the solar cell silicon substrate, wherein the thickness of the mask layer is 50 nm;

[0098] (3) forming a patterned groove in a preset gate line area on the back side of the solar cell silicon substrate by laser film opening, wherein the groove has a width of 5 μm and a depth of 100 nm, and simultaneously removing the back mask layer in the film opening area to expose the silicon substrate;

[0099] (4) forming a patterned groove in a preset gate line area on the front side of the solar cell silicon substrate by laser film opening, wherein the groove has a width of 5 μm and a depth of 100 nm;

[0100] (5) Add an appropriate amount of KOH to the pure water solution, circulate and stir evenly to prepare a roughening agent, the concentration of the KOH solution is 20-30%; first use a suction cup to absorb the front side of the solar cell silicon substrate, and float the back side in the roughening agent. The roughening time is 15 seconds. After the roughening is completed, remove the mask layer in the non-preset gate line area;

[0101] (6) Add an appropriate amount of hydrofluoric acid to the pure water solution, stir it evenly in a circulation cycle, and prepare an acid pickling agent. The amount of hydrofluoric acid added to the hydrofluoric acid solution is 20 mL / L, the temperature of the acid pickling agent is 25°C, and the acid pickling time is 50 s. The specific operation is: first use a conductive suction cup to absorb the front side of the solar cell silicon substrate after the film is opened, and clean the roughened solar cell in the acid pickling agent. After cleaning, move the suction cup to the nickel electroplating tank position, and float the back side in the nickel electroplating solution for a period of time. At the same time, turn on the light source and the movable anode device to start electroplating. The moving speed of the electroplating anode is 30 cm / min. After the electroplating is completed, clean and dry the back side of the silicon substrate, turn it over and electroplate the front side of the silicon substrate according to the above method. After both sides are plated, a double-sided nickel-plated solar cell silicon substrate is obtained. The drying temperature is 20°C.

[0102] (7) The silicon substrate of the solar cell with double-sided nickel plating is copper plated on both sides, and the thickness of the copper plating layer is 0.5 μm;

[0103] (8) performing heat treatment annealing on the double-sided thin copper solar cell through a sintering furnace;

[0104] (9) Pickling the annealed double-sided thin copper solar cell with a sulfuric acid solution concentration of 10-15% and a pickling time of 20 seconds;

[0105] (10) The double-sided thin copper solar cell after pickling is electroplated with normal copper and tin on both sides in sequence to obtain a finished metallized solar cell, wherein the thickness of the copper plating layer is 9 μm and the thickness of the tin plating layer is 2 μm.

[0106] Example 2

[0107] This embodiment provides a method for preparing a double-sided metallized solar cell, comprising the following steps:

[0108] (1) Providing a solar cell silicon substrate, the solar cell substrate comprising a silicon substrate and a coating layer deposited on the surface of the silicon substrate, the coating layer being a silicon nitride film, and the thickness of the silicon nitride film being 100 nm;

[0109] (2) preparing a mask layer on the back coating layer of the solar cell silicon substrate, wherein the thickness of the mask layer is 15 nm;

[0110] (3) forming a patterned groove in a preset gate line area on the back side of the solar cell silicon substrate by laser film opening, wherein the groove has a width of 50 μm and a depth of 50 nm, and simultaneously removing the back mask layer in the film opening area to expose the silicon substrate;

[0111] (4) forming a patterned groove in a preset gate line area on the front side of the solar cell silicon substrate by laser film opening, wherein the groove has a width of 50 μm and a depth of 50 nm;

[0112] (5) Add an appropriate amount of TMAH solution to the pure water solution, circulate and stir evenly to prepare a roughening agent, the concentration of the TMAH solution is 20-25%; first use a suction cup to absorb the front side of the solar cell silicon substrate, and float the back side on the roughening agent for 30 seconds. During the roughening process, remove the mask layer in the non-preset gate line area;

[0113] (6) Add an appropriate amount of hydrofluoric acid to the pure water solution, stir it evenly in a circulation cycle, and prepare an acid pickling agent. The amount of hydrofluoric acid added to the hydrofluoric acid solution is 10 mL / L, the temperature of the acid pickling agent is 38°C, and the acid pickling time is 5s. The specific operation is: first use a conductive suction cup to absorb the front side of the solar cell silicon substrate after the film is opened, and clean the roughened solar cell in the acid pickling agent. After cleaning, move the suction cup to the nickel electroplating tank position, and float the back side in the nickel electroplating solution for a period of time. At the same time, turn on the light source and the movable anode device to start electroplating. The moving speed of the electroplating anode is 50 cm / min. After the electroplating is completed, clean and dry the back side of the silicon substrate, turn it over and electroplate the front side of the silicon substrate according to the above method. After both sides are plated, a double-sided nickel-plated solar cell silicon substrate is obtained. The drying temperature is 15°C.

[0114] (7) The double-sided nickel-plated silicon substrate of the solar cell is plated with thin copper on both sides, and the thickness of the copper plating layer is 1 μm;

[0115] (8) performing heat treatment annealing on the double-sided thin copper solar cell through a sintering furnace;

[0116] (9) Pickling the annealed double-sided thin copper solar cell with a sulfuric acid solution concentration of 10-15% and a pickling time of 10 seconds;

[0117] (10) The double-sided thin copper solar cell after pickling is electroplated with normal copper and tin on both sides in sequence to obtain a finished metallized solar cell, wherein the thickness of the copper plating layer is 12 μm and the thickness of the tin plating layer is 1 μm.

[0118] Example 3

[0119] This embodiment provides a method for preparing a double-sided metallized solar cell, comprising the following steps:

[0120] (1) Providing a solar cell silicon substrate, the solar cell substrate comprising a silicon substrate and a coating layer deposited on the surface of the silicon substrate, the coating layer being a silicon nitride film, and the thickness of the silicon nitride film being 75 nm;

[0121] (2) preparing a mask layer on the back coating layer of the solar cell silicon substrate, wherein the thickness of the mask layer is 35 nm;

[0122] (3) forming a patterned groove in a preset gate line area on the back side of the solar cell silicon substrate by laser film opening, wherein the groove has a width of 30 μm and a depth of 75 nm, and simultaneously removing the back mask layer in the film opening area to expose the silicon substrate;

[0123] (4) forming a patterned groove in a preset gate line area on the front side of the solar cell silicon substrate by laser film opening, wherein the groove has a width of 30 μm and a depth of 75 nm;

[0124] (5) Add an appropriate amount of TMAH solution to the pure water solution, circulate and stir evenly to prepare a roughening agent, the concentration of the TMAH solution is 20-25%; first use a suction cup to absorb the front side of the solar cell silicon substrate, and float the back side on the roughening agent for 25 seconds. During the roughening process, remove the mask layer in the non-preset gate line area;

[0125] (6) Add an appropriate amount of hydrofluoric acid to the pure water solution, stir it evenly in a cycle, and prepare an acid pickling agent. The amount of hydrofluoric acid added to the hydrofluoric acid solution is 15 mL / L, the temperature of the acid pickling agent is 30°C, and the acid pickling time is 35 s. The specific operation is: first use a conductive suction cup to absorb the front side of the solar cell silicon substrate after the film is opened, and clean the roughened solar cell in the acid pickling agent. After cleaning, move the suction cup to the nickel electroplating tank position, and float the back side in the nickel electroplating solution for a period of time. At the same time, turn on the light source and the movable anode device to start electroplating. The moving speed of the electroplating anode is 40 cm / min. After the electroplating is completed, clean and dry the back side of the silicon substrate, turn it over and electroplate the front side of the silicon substrate according to the above method. After both sides are plated, a double-sided nickel-plated solar cell silicon substrate is obtained. The drying temperature is 18°C.

[0126] (7) The silicon substrate of the solar cell with double-sided nickel plating is copper plated on both sides, and the thickness of the copper plating layer is 0.8 μm;

[0127] (8) performing heat treatment annealing on the double-sided thin copper solar cell through a sintering furnace;

[0128] (9) Pickling the annealed double-sided thin copper solar cell with a sulfuric acid solution concentration of 13% and a pickling time of 15 seconds;

[0129] (10) The double-sided thin copper solar cell after pickling is electroplated with normal copper and tin on both sides in sequence to obtain a finished metallized solar cell, wherein the thickness of the copper plating layer is 10 μm and the thickness of the tin plating layer is 1.5 μm.

[0130] Example 4

[0131] This embodiment provides a method for preparing a double-sided metallized solar cell, which differs from embodiment 3 in that: in step 7, thin copper is plated on both sides, and the thickness of the copper plated layer is 0.4 μm.

[0132] Example 5

[0133] This embodiment provides a method for preparing a double-sided metallized solar cell, which differs from embodiment 3 in that: in step 7, thin copper is plated on both sides, and the thickness of the copper plated layer is 1.1 μm.

[0134] Comparative Example 1

[0135] This comparative example provides a method for preparing a double-sided metallized solar cell, which differs from Example 3 in that step 5, ie, roughening treatment, is not performed.

[0136] Comparative Example 2

[0137] This comparative example provides a method for preparing a double-sided metallized solar cell, which differs from Example 3 in that step 7, that is, the thin copper electroplating process, is not performed.

[0138] Test Case

[0139] Test sample: double-sided metallized solar cell prepared by Examples 1-5 and Comparative Examples 1-2.

[0140] Test method: (1) Welding tension under low temperature conditions: tensile tester.

[0141] The test results are shown in Table 1.

[0142] Table 1

[0143]

[0144] It can be seen from the data in Table 1 that when the thickness of the thin copper layer is too thick or too thin, the grid line bonding strength is not high. When the thickness of the thin copper layer is within a specific range, the battery grid line bonding strength is strong. It can be seen that the thin copper electroplating process can effectively form a nickel-silicon alloy, improve the bonding strength, and avoid nickel surface oxidation. The overall process is simpler and faster without the need for an additional nickel removal process. Moreover, if the roughening treatment or the thin copper electroplating process is not performed, the grid line bonding strength of the battery is poor.

[0145] The method for preparing a double-sided metallized solar cell provided by the present invention can achieve rapid preparation and a coating with strong bonding strength between the coating and the substrate and good uniformity. It can be applied to solar cells, can improve the bonding strength between the seed layer and the substrate, prepare high and wide uniform grid lines, and at the same time achieve rapid preparation of the seed layer, optimize the solar cell metallization process and improve efficiency.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a double-sided metallized solar cell, characterized in that: The method for preparing a double-sided metallized solar cell comprises the following steps: Laser-cutting the silicon substrate of the solar cell to form grooves in the preset grid line area, and roughening the back surface of the silicon substrate of the solar cell after cutting with a roughening agent; Then, the solar cell silicon substrate is subjected to double-sided nickel plating, first double-sided copper plating, annealing, second double-sided copper plating, and double-sided tin plating in sequence to obtain a double-sided metallized solar cell; The roughening agent is one of a KOH solution and a TMAH solution; The thickness of the copper layer of the first double-sided copper plating is 0.5-1 μm.

2. The method for preparing a double-sided metallized solar cell according to claim 1, wherein: Before laser opening the silicon substrate of the solar cell, a mask layer is prepared on the back side of the silicon substrate of the solar cell.

3. The method for preparing a double-sided metallized solar cell according to claim 2, wherein: The solar cell silicon substrate comprises a silicon substrate and a coating layer deposited on the surface of the silicon substrate, and the mask layer is deposited on the surface of the coating layer.

4. The method for preparing a double-sided metallized solar cell according to claim 3, wherein: The coating layer is a silicon nitride film, and the thickness of the silicon nitride film is 50-100 nm.

5. The method for preparing a double-sided metallized solar cell according to claim 3, wherein: The thickness of the mask layer is 15-50 nm.

6. The method for preparing a double-sided metallized solar cell according to claim 1, wherein: The groove has a width of 5-50 μm and a depth of 50-100 nm.

7. The method for preparing a double-sided metallized solar cell according to claim 1, wherein: The concentration of the KOH solution is 20-30%, and the concentration of the TMAH solution is 20-25%.

8. The method for preparing a double-sided metallized solar cell according to claim 1, wherein: The roughening time is 15-30 s.

9. The method for preparing a double-sided metallized solar cell according to claim 2, wherein: During the roughening process, the mask layer in the non-preset gate line region is removed.

10. The method for preparing a double-sided metallized solar cell according to claim 1, wherein: After forming the grooves on the back side of the solar cell silicon substrate and before roughening, the mask layer in the film opening area on the back side of the solar cell silicon substrate is removed to expose the silicon substrate.

11. The method for preparing a double-sided metallized solar cell according to claim 1, wherein: After roughening the solar cell silicon substrate and before double-sided nickel plating, the roughened solar cell silicon substrate is cleaned.

12. The method for preparing a double-sided metallized solar cell according to claim 11, characterized in that: Acid cleaning agent is used to clean the silicon substrate of solar cells.

13. The method for preparing a double-sided metallized solar cell according to claim 12, wherein: The pickling agent is hydrofluoric acid solution.

14. The method for preparing a double-sided metallized solar cell according to claim 13, wherein: The amount of hydrofluoric acid added to the hydrofluoric acid solution is 10-20 mL / L.

15. The method for preparing a double-sided metallized solar cell according to claim 12, wherein: The temperature of the pickling agent is 25-38°C.

16. The method for preparing a double-sided metallized solar cell according to claim 12, wherein: The pickling time is 5-50 s.

17. The method for preparing a double-sided metallized solar cell according to claim 12, wherein: After pickling the silicon substrate of the solar cell, it is electroplated with metal nickel and then blown dry.

18. The method for preparing a double-sided metallized solar cell according to claim 17, characterized in that: The drying temperature is 15-20℃.

19. The method for preparing a double-sided metallized solar cell according to claim 1, wherein: The thickness of the copper plating layer of the second double-sided copper plating is 9-12 um.

20. The method for preparing a double-sided metallized solar cell according to claim 1, wherein: The thickness of the double-sided tinned layer is 1-2 um.

21. The method for preparing a double-sided metallized solar cell according to claim 1, wherein: After annealing, and before the second double-sided copper plating, the double-sided copper-plated solar cell is pickled.

22. The method for preparing a double-sided metallized solar cell according to claim 21, wherein: The pickling adopts sulfuric acid solution.

23. The method for preparing a double-sided metallized solar cell according to claim 22, wherein: The concentration of the sulfuric acid solution is 10-15%.

24. The method for preparing a double-sided metallized solar cell according to claim 21, wherein: The pickling time is 10-20 s.

25. The method for preparing a double-sided metallized solar cell according to claim 1, characterized in that: A solar cell silicon substrate is electroplated using a movable anode device, wherein the movable anode device comprises an electroplating anode (100) and a movable component; The electroplating anode (100) is arranged below the solar cell silicon substrate to be plated with metal, and the end of the electroplating anode (100) is connected to the moving component, and the moving component can drive the electroplating anode (100) to move, so as to electroplate metal on the solar cell silicon substrate.

26. The method for preparing a double-sided metallized solar cell according to claim 25, characterized in that: The movable anode device comprises two movable components, the two movable components being a first movable component (200) and a second movable component (300); The first moving component (200) is connected to one end of the electroplating anode (100), and the second moving component (300) is connected to the other end of the electroplating anode (100).

27. The method for preparing a double-sided metallized solar cell according to claim 25, characterized in that: The electroplating anode (100) comprises one or more of an iridium-based titanium-based metal oxide anode, a ruthenium-based titanium-based metal oxide anode, and a lead dioxide-based titanium-based metal oxide anode.

28. The method for preparing a double-sided metallized solar cell according to claim 25, wherein: The electroplating anode (100) is in a strip shape.

29. The method for preparing a double-sided metallized solar cell according to claim 25, wherein: The moving speed of the electroplating anode (100) is 30-50 cm / min.

30. The method for preparing a double-sided metallized solar cell according to claim 26, wherein: The first moving assembly (200) comprises a first moving chain (210) and a first connecting block (220); The first connecting block (220) is connected to one end of the electroplating anode (100), the first moving chain (210) is connected to the first connecting block (220), and the first moving chain (210) is movable to drive the first connecting block (220) to move; The second moving assembly (300) comprises a second moving chain (310) and a second connecting block (320); The second connecting block (320) is connected to an end of the electroplating anode (100) away from the first connecting block, and the second movable chain (310) is connected to the second connecting block (320). The second movable chain (310) is movable to drive the second connecting block (320) to move.

31. The method for preparing a double-sided metallized solar cell according to claim 26, wherein: The movable anode device further comprises an electroplating tank (400), a suction cup (500) and a light source component; The electroplating tank (400) is used to contain an electroplating solution, and the electroplating anode (100) is placed in the electroplating tank (400); The suction cup (500) is arranged above the electroplating tank (400) and is used to absorb the solar cell silicon substrate to be plated with metal; The light source component is arranged below the electroplating tank (400) and is used to illuminate the light source (600) into the electroplating tank (400).

32. A double-sided metallized solar cell prepared by the method for preparing a double-sided metallized solar cell according to any one of claims 1 to 31.

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