A solar cell metallized electrode and its preparation method

Abstract

The present invention relates to the field of solar cells, and in particular to a metallized electrode for a solar cell and a method for preparing the same. The method for preparing the metallized electrode for a solar cell comprises: step 1, preparing an electroforming template; step 2, electroforming a metal electrode; step 3, transferring the metal electrode to a carrier film; and step 4, combining the carrier film with the solar cell. The present invention can greatly increase the strength and flexibility of solar cells and reduce the risk of breakage during the production and assembly process by combining metal electrodes with component packaging processes. At the same time, by improving the material of the packaging film, the thermal conductivity of the packaging film is improved, the temperature of the solar panel assembly is reduced, and the service life of the solar panel assembly is extended.

Description

Technical Field

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

[0002] Solar cells convert sunlight directly into electricity and are a clean, renewable energy technology. Their widespread adoption will help reduce dependence on fossil fuels, lower greenhouse gas emissions, promote the global transition to a low-carbon economy, and address climate change challenges. Solar cell metallization technology is a key factor in determining solar cell conversion efficiency. Currently, the mainstream metallization technology uses screen-printed silver paste. This involves screen-printing silver paste onto the front and back sides of a silicon wafer to form an electrode pattern. This pattern is then sintered at high temperatures or cured at low temperatures to form silver electrodes, which can conduct the photocurrent generated within the cell to the external circuit. While the screen-printing process is mature and simple, silver paste comprises approximately 90% silver powder particles, making it difficult to sustainably reduce cell processing costs. Silver is a precious metal with a high price and limited global reserves. As the photovoltaic industry continues to expand, the supply and cost control of silver paste raw materials are facing significant pressure. Therefore, developing new metallization technologies to replace screen-printed silver paste, reduce reliance on precious metals, and further reduce power generation costs, is of great significance to the solar cell industry.

[0003] Furthermore, as the cost of photovoltaic power generation continues to decline, it will rapidly replace other traditional fossil fuel-based power generation methods as a new, more economical power generation method. However, solar panel modules generate a significant amount of heat during the power generation process. If this heat is not dissipated promptly, the temperature of the solar panel modules will continue to rise, affecting the photovoltaic conversion efficiency and service life of the solar panel modules. Therefore, reducing the temperature of solar panel modules and improving their thermal conductivity are particularly important. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention aims to provide a solar cell metallized electrode and a preparation method thereof.

[0005] The purpose of the present invention is achieved by adopting the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing a metallized electrode for a solar cell, comprising the following steps:

[0007] Step 1: Preparation of electroforming template:

[0008] One side of the polished metal substrate is welded with a power circuit and coated with an insulating layer, and then an electroplating resist layer is deposited, and then a portion of the electroplating resist layer is etched according to the electrode pattern;

[0009] Step 2: Electroforming metal electrodes:

[0010] Prepare an electroplating solution, immerse the electroformed template obtained in the first step as a cathode in the electroplating solution, and connect the side with the conductive circuit to an external power supply. Apply power to perform electroforming, wash, and dry to obtain an electroformed metal electrode.

[0011] Step 3: Transfer the metal electrode to the carrier film:

[0012] A carrier film is prepared and stretched to cover the electrode surface. The film is heated and pressurized to embed the film into the side where the electroformed metal electrode is deposited. After cooling, the carrier film and the metal electrode are peeled off. The peeled carrier film and the metal electrode are then subjected to secondary electroplating to obtain a carrier film embedded with the metal electrode.

[0013] Step 4: Combining the carrier film with the solar cell:

[0014] The carrier film embedded with the metal electrode is laminated and packaged with the solar cell, and fixed to obtain the metallized electrode of the solar cell.

[0015] Preferably, in step 1, the electroforming template consists of a metal substrate, an anti-plating layer, a conductive circuit, a power supply circuit and an insulating layer.

[0016] Preferably, in step 1, the metal substrate is an alloy of one or more metals selected from copper, aluminum, titanium, and nickel, and the alloy is cast and rolled to form a metal sheet or a flexible metal strip (foil).

[0017] Preferably, in step 1, the anti-electroplating layer is one or a combination of two or more of silicon nitride, aluminum oxide, silicon oxide, polyimide, polytetrafluoroethylene, and epoxy resin.

[0018] More preferably, the thickness of the anti-electroplating layer is 50nm~10um.

[0019] Preferably, in step 1, the conductive circuit is an exposed area of ​​the metal substrate formed by removing a portion of the anti-plating layer through a laser etching or photoresist etching process.

[0020] Preferably, in step 1, the energized wire is one of copper wire, aluminum wire and iron wire.

[0021] Preferably, in step 1, the insulating layer is obtained by coating with insulating varnish.

[0022] Preferably, in step 1, the etching process is laser etching or photoresist etching.

[0023] More preferably, the etching process uses an ultraviolet laser with a wavelength of 355 nm or a green laser with a wavelength of 532 nm to focus and irradiate the anti-plating layer according to the electrode pattern, and remove part of the anti-plating layer area to form a bare metal substrate.

[0024] Preferably, in step 2, the electroplating solution is one or a combination of two or more of the following: electroplating solutions for nickel, copper, tin, copper-tin alloy, and tin-nickel alloy.

[0025] Preferably, in step 2, the electroplating template is entirely immersed below the liquid level of the electroplating solution, the electroformed template is connected to the negative electrode of the external DC power supply through the power circuit on the back, and the electroplating anode is connected to the positive electrode of the external DC power supply.

[0026] Preferably, in step 2, the voltage of the DC power supply during electroforming is 0.3-10V, and the current density is 0.1-10A / dm 2 , the electroforming time is 1~15min.

[0027] Preferably, in step 2, when multi-layer electroplating is required, the operation of step 2 should be repeated in sequence.

[0028] Preferably, in step 2, washing is to rinse away excess plating solution from the electroforming template using pure water, and drying is to dry the electroforming template, with a drying time of 100-600s and a drying temperature of 50-95°C.

[0029] Preferably, in step 3, the secondary electroplating is to connect the peeled carrier film together with the metal electrode to the negative pole of a DC power supply and immerse them in a tin electroplating tank to complete the tin electroplating.

[0030] Preferably, in step 3, washing and drying are also required after the secondary electroplating. The washing is to use pure water to clean the tinned carrier film together with the metal electrode, and the cleaning time is 60~300s; the drying is to dry the cleaned carrier film together with the metal electrode, and the drying temperature is 50~70℃, and the drying time is 60~300s.

[0031] Preferably, in step 4, the carrier film inlaid with metal electrodes is laid flat on the front and back of the solar cell, wherein the side of the carrier film with the metal electrodes faces the surface of the solar cell.

[0032] Preferably, in step 4, the lamination is performed by aligning the three-layer structure of carrier film / solar cell / carrier film, feeding the structure into a laminating device, applying uniform pressure to the carrier film and the solar cell, and heating the structure at the same time, with the heating temperature being 130-160° C. and the pressurizing time being 10-120 seconds.

[0033] Preferably, in step 3, the carrier film is a thermally conductive PET / POE composite film, and the preparation method includes:

[0034] (1) Weigh POE resin (polyolefin elastomer) and thermal conductive filler and mix them evenly in a blender. The weight ratio of POE resin to thermal conductive filler is 100:2-10. Then, co-extrude and cast at 100-110°C to obtain a modified POE film.

[0035] (2) The PET film (polyethylene terephthalate) is first subjected to corona treatment, and then the modified POE film and the PET film are laminated and hot-pressed at a temperature of 150-175°C, a pressure of 3-5 MPa, and a holding time of 4-10 seconds to obtain a thermally conductive PET / POE composite film.

[0036] Preferably, the thickness of the PET film layer is 10-50 μm, and the thickness of the modified POE film layer is 5-10 μm.

[0037] Preferably, the preparation method of the thermally conductive filler comprises:

[0038] S1. Weigh aluminum nitride nanoparticles, γ-mercaptopropyltriethoxysilane, ethanol, and deionized water, mix thoroughly, and stir at 50-60°C for 5-10 hours. Then, vacuum filter, wash with pure water three times, and vacuum dry to obtain mercapto-modified aluminum nitride.

[0039] S2. Weigh allyl alcohol glycidyl ether and 5-aminobenzotriazole, add them to tetrahydrofuran solvent, stir thoroughly, adjust the pH to 9.0-10.0, then heat to 50-70° C., keep stirring for 6-12 hours. After the reaction is completed, adjust the reaction solution to neutral, extract and collect the organic phase, and remove the solvent under reduced pressure to obtain a benzotriazole derivative;

[0040] S3. Weigh the thiol-modified aluminum nitride and add it to the solvent tetrahydrofuran, disperse it evenly by ultrasonication, add benzotriazole derivatives and photoinitiator in an inert gas atmosphere, place it at room temperature, irradiate it under UV light, separate the product by centrifugation, wash it with ethanol three times, and vacuum dry it to obtain a thermally conductive filler.

[0041] Preferably, in S1, the purity of the aluminum nitride nanoparticles is ≥99.99%, and the particle size is 50-60 nm.

[0042] Preferably, in S1, the mass ratio of aluminum nitride nanoparticles, γ-mercaptopropyltriethoxysilane, ethanol and deionized water is 1:0.24~0.48:10~20:5~10.

[0043] Preferably, in S2, the mass ratio of allyl alcohol glycidyl ether, 5-aminobenzotriazole and tetrahydrofuran is 1.25-1.48:1.34:10-30.

[0044] Preferably, in S3, the mass ratio of the thiol-modified aluminum nitride, the benzotriazole derivative, and tetrahydrofuran is 1:0.43-0.65:10-30.

[0045] Preferably, in S3, the parameters of the UV light include: 365 nm, 10-50 mW / cm 2 , the irradiation time is 30~90min.

[0046] Preferably, in S3, the photoinitiator is Irgacure 2959, and the added mass is 1% to 5% of the mass of the benzotriazole derivative.

[0047] In a second aspect, the present invention provides a metallized electrode for a solar cell, which is prepared using the above-mentioned preparation method.

[0048] The beneficial effects of the present invention are:

[0049] 1. Compared to traditional solar cell screen-printed silver paste sintered electrodes, this invention significantly reduces silver consumption by over 80%. Specifically, silver consumption is reduced to zero in heterojunction (HJT) cells, perovskite cells (PSCs), and copper indium gallium selenide (CIGS) cells, reducing the solar cell metallization process's reliance on precious metals. Furthermore, the electroformed metal electrodes are closer to the metal's intrinsic conductivity, resulting in a denser, lower resistivity than sintered metal electrodes, which helps reduce conduction resistance and improve solar cell conversion efficiency.

[0050] 2. By combining metal electrodes with a component packaging process, this invention significantly increases the strength and flexibility of solar cells, reducing the risk of breakage during production and assembly. Furthermore, by improving the material of the encapsulating film, the thermal conductivity of the film is enhanced, reducing the temperature of the solar panel assembly and extending the service life of the solar panel assembly.

[0051] 3. This invention utilizes a thermally conductive PET / POE composite film as the carrier film. This film is obtained by co-extruding a modified POE material with a PET substrate. This carrier film with excellent thermal properties dissipates heat more quickly, preventing localized overheating and protecting the battery from thermal damage. While maintaining high transmittance and thermal conductivity, it also enhances mechanical strength and stability, and exhibits excellent aging resistance.

[0052] 4. The modified POE material is a POE resin modified with a thermally conductive filler. The thermally conductive filler is a product of thiol-modified aluminum nitride particles combined with a benzotriazole derivative through a click reaction between the thiol group and the double bond. The benzotriazole derivative is obtained by the amino-epoxy ring-opening reaction of 5-aminobenzotriazole and allyl alcohol glycidyl ether. The resulting benzotriazole derivative contains both unsaturated double bonds and benzotriazole groups. The thermally conductive filler, through the synergistic effect of its surface functional groups (such as sulfide, imine, and benzotriazole), gives the carrier film material better interfacial adhesion, light stability, and dimensional stability, especially excellent light stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The present invention is further described with reference to the accompanying drawings. However, the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without creative effort.

[0054] Figure 1 It is a schematic diagram of the structure of the electroforming template of the present invention deposited in the electroplating tank;

[0055] Figure 2 This is a schematic structural diagram of the combination of the metal electrode and the solar cell of the present invention;

[0056] Figure 3 This is a schematic diagram of the process of nickel plating, copper plating and tin plating of the metal electrode of the present invention;

[0057] Figure 4 It is a structural schematic diagram of the electroforming template of the present invention;

[0058] Figure 5 Schematic diagram of the metal electrode embedded in the carrier film of the present invention;

[0059] Figure 6 This is a schematic diagram of the series structure of solar cells combined with metal electrode films of the present invention;

[0060] Figure 7 1 is a SEM schematic diagram of the electroformed metal electrode of Example 1 of the present invention;

[0061] Figure 8 This is a SEM schematic diagram of a metal electrode prepared by screen-printing silver-coated copper paste in Comparative Example 1 of the present invention;

[0062] Figure 9 This is a 3D microscope image of an electroformed metal electrode embedded in a carrier film according to Example 1 of the present invention;

[0063] Figure 10 This is a 3D microscope image of a metal electrode prepared by screen-printing silver-coated copper paste in Comparative Example 1 of the present invention.

[0064] Figure numerals: 1-metal substrate, 2-anti-electroplating layer, 3-conductive circuit, 4-power-on circuit, 5-insulating layer, 6-electroplating tank, 7-electroplating solution, 8-electroplating anode plate, 9-DC power supply, 10-metal electrode, 11-carrier film, 12-battery cell; 21-nickel plating tank, 22-first water washing tank, 23-copper plating tank, 24-second water washing tank, 25-tin plating tank, 26-third water washing tank, 27-drying tank. DETAILED DESCRIPTION

[0065] In order to more clearly illustrate the present invention and have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0066] Unless otherwise specified, the raw materials, reagents, or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0067] The present invention will be further described below with reference to the following examples.

[0068] A method for preparing a metallized electrode for a solar cell comprises the following steps:

[0069] Step 1: Preparation of electroforming template:

[0070] (1) Installation and insulation treatment of the power line 4: The power line 4 is welded to one side of the polished metal substrate 1 and coated with an insulating layer 5.

[0071] (2) Depositing an anti-electroplating layer 2: Depositing an anti-electroplating layer 2 with a thickness of 50 nm to 10 μm on the surface of the polished metal substrate 1. The anti-electroplating layer 2 is an anti-electroplating polyester film; the anti-electroplating layer 2 is annealed and cured to enhance wear resistance and adhesion.

[0072] (3) Opening the anti-electroplating layer 2: Using a UV laser with a wavelength of 355 nm or a green laser with a wavelength of 532 nm, focus irradiation is used to remove the anti-electroplating layer 2 in a part of the area, forming a bare surface area of ​​the metal substrate 1 according to the electrode pattern, and forming a conductive circuit 3.

[0073] Step 2: Metal electrode 10:

[0074] (1) Prepare electroplating solution 7: Use commercial nickel plating, copper plating, and tin plating solution 7 and electroplating anode plate 8, and pour the above plating solutions into nickel plating tank 21, copper plating tank 23, and tin plating tank 25 for nickel plating, copper plating, and tin plating, respectively, for use;

[0075] (2) Immerse the electroformed template as a cathode in the nickel plating tank 21 prepared in step (1), and immerse the entire electroformed template below the surface of the plating solution. The electroformed template is connected to the negative electrode of the external DC power supply 9 through the power line 4 on the back, and the electroplating anode is connected to the positive electrode of the external DC power supply 9.

[0076] (3) Electroforming: The voltage of DC power supply 9 is 0.3~10V, and the current density is 0.1~10A / dm 2 , electroforming time is 1~15min;

[0077] (4) Water washing: The electroformed template is taken out from the nickel plating tank 21, and the excess plating solution of the electroformed template is washed away with pure water to complete the deposition of the nickel layer;

[0078] (5) Repeat steps (2), (3) and (4) in sequence to complete the deposition of copper and tin layers in the copper plating tank 23 and the tin plating tank 25, respectively.

[0079] (6) Drying: Dry the electroformed template for 100~600s at a temperature of 50~95℃.

[0080] Step 3: Transfer the metal electrode 10 to the carrier film 11:

[0081] (1) Preparation of carrier film 11: The carrier film 11 is obtained by composite extrusion of the modified POE material and the PET substrate.

[0082] (2) Laminating the carrier film 11: The carrier film 11 is stretched and laid flat on the side of the electroforming template where the metal electrode 10 is deposited.

[0083] (3) Lamination treatment: Apply uniform pressure to the electroforming template and carrier film 11 laid out in step (2), and heat to 75-120°C at the same time, so that the carrier film 11 is slightly melted and the metal electrode 10 is embedded in the carrier film 11.

[0084] (4) After the treatment in step (3), the electroforming template and the carrier film 11 are cooled to room temperature, and the carrier film 11 together with the metal electrode 10 are peeled off from the electroforming template.

[0085] (5) The peeled carrier film 11 together with the metal electrode 10 is connected to the negative pole of the DC power supply 9 and immersed in the tin plating tank 25 to complete the tin electroplating.

[0086] (6) Pure water cleaning step (5) The tinned carrier film 11 and the metal electrode 10 are cleaned for 60 to 300 seconds.

[0087] (7) Drying the carrier film 11 and the metal electrode 10 after cleaning in step (6). The drying temperature is 50-70°C and the drying time is 60-300s.

[0088] Step 4: Combining the carrier film 11 with the solar cell:

[0089] (1) A carrier film 11 inlaid with metal electrodes 10 is laid flat on the front and back of the solar cell 12, wherein the side of the carrier film 11 with the metal electrodes 10 faces the surface of the solar cell.

[0090] (2) After completing step (1), the substrate is fed into a laminating device, where uniform pressure is applied to the carrier film 11 and the cell 12 while heating them. The heating temperature is 130-160°C and the pressing time is 10-120 seconds.

[0091] (3) After completing step (2), the battery cell 12 is packaged with the carrier film 11 and the metal electrode 10.

[0092] Example 1: A method for preparing a metallized electrode for a solar cell, comprising the following steps:

[0093] (1) Preparation of electroforming template: A polished stainless steel substrate is used as the metal substrate 1, and a copper wire is welded on the back as the power line 4. The power line 4, the entire back of the metal substrate, and the edges are insulated with insulating paint. On the front of the metal substrate, a 5 μm thick silicon nitride film layer is deposited using a chain PVD method to form an anti-electroplating layer 2. Finally, according to the design of the electrode pattern, a UV laser with a wavelength of 355 nm is used to focus on the anti-electroplating layer 2 to remove the silicon nitride layer in the area where the metal electrode 10 is to be deposited, thus forming a conductive circuit 3.

[0094] (2) Electroforming metal electrode 10: Connect the back side of the electroforming template prepared in step (1) to the negative pole of the constant current power supply and immerse it in the first nickel plating tank 21 of the electroplating tank 6. The first nickel plating tank 21 contains nickel plating solution 7, with a voltage of 3V and a current density of 3A / dm 2 , the power-on time is 3min, and the plating solution temperature is 30℃. After the nickel plating is completed, the electroformed template is transferred to the first water washing tank 22, and the water washing time is 100s. Next, the electroformed template is transferred to the copper plating tank 23, connected to the negative pole of the constant current power supply, the power-on voltage is 0.8V, and the power-on current density is 5A / dm 2 , the power-on time is 3min, and the plating solution temperature is room temperature. Then transfer the electroformed template to the second water washing tank 24, and the water washing time is 100s. Transfer the electroformed template to the tin plating tank 25, connect the negative pole of the constant current power supply, the power-on voltage is 0.8V, and the power-on current is 3A / dm 2 The electroformed template is then transferred to the third washing tank 26 for 100 seconds and then to the drying tank 27 for drying at 75°C for 500 seconds.

[0095] (3) Transferring the metal electrode 10 to the carrier film 11: A heat-conductive PET / POE composite film is used as the carrier film 11 (prepared as in Example 4), with a PET layer thickness of 30um and a POE layer thickness of 8um. The POE material side of the carrier film 11 is laid flat on the side of the electroforming template on which the metal electrode 10 is electroformed. After uniformly applying pressure, the carrier film 11 is infrared-heated to 110°C for 40 seconds. The metal electrode 10 is embedded in the carrier film 11, and then the metal electrolytic carrier film 11 is peeled off from the electroforming template. After the metal electrode 10 on the carrier film 11 is connected to the negative pole of a constant current power supply, it is immersed in a tin plating tank 25 to complete the tin plating of the surface of the metal electrode 10. The power-on voltage is 0.8V and the power-on current is 3A / dm 2 The electroformed template was then transferred to a water washing tank for 100 seconds and then to a drying tank for 500 seconds at 75°C.

[0096] (4) Bonding the carrier film 11 to the cell 12: The carrier film 11 containing the metal electrode 10 is laid flat on the front and back of the solar cell, with the side of the carrier film 11 with the metal electrode 10 facing the surface of the solar cell. The secondary grid portion of the metal electrode 10 contacts the surface of the solar cell, and the main grid portion of the metal electrode 10 extends outside the solar cell. The main grid portion on the front and the main grid portion on the back are distributed on both sides of the solar cell. After the three-layer structure of carrier film 11 / solar cell / carrier film 11 is aligned, uniform pressure is applied and the carrier film 11 is infrared heated at a temperature of 150°C and a heating and extrusion time of 80 seconds.

[0097] Example 2: A method for preparing a metallized electrode for a solar cell, comprising the following steps:

[0098] (1) Preparation of electroforming template: A polished stainless steel substrate is used as the metal substrate 1, and a copper wire is welded on the back as the power line 4. The power line 4, the entire back of the metal substrate, and the edges are insulated with insulating paint. On the front of the metal substrate, a 2 μm thick silicon nitride film layer is deposited using a chain PVD method to form an anti-electroplating layer 2. Finally, according to the design of the electrode pattern, a green laser with a wavelength of 532 nm is used to focus on the anti-electroplating layer 2 to remove the silicon nitride layer in the area where the metal electrode 10 is to be deposited, thus forming a conductive circuit 3.

[0099] (2) Electroforming metal electrode 10: Connect the back side of the electroforming template prepared in step (1) to the negative pole of the constant current power supply and immerse it in the first nickel plating tank 21 of the electroplating tank 6. The first nickel plating tank 21 contains nickel plating solution 7, with a voltage of 3V and a current density of 1A / dm 2, the power-on time is 5min, and the plating solution temperature is 35℃. After the nickel plating is completed, the electroformed template is transferred to the first water washing tank 22, and the water washing time is 150s. Next, the electroformed template is transferred to the copper plating tank 23, connected to the negative pole of the constant current power supply, the power-on voltage is 0.5V, and the power-on current density is 3A / dm 2 , the power-on time is 5min, and the plating solution temperature is room temperature. Then transfer the electroformed template to the second water washing tank 24, and the water washing time is 150s. Transfer the electroformed template to the tin plating tank 25, connect the negative pole of the constant current power supply, the power-on voltage is 1V, and the power-on current is 1A / dm 2 The electroformed template is then transferred to the third washing tank 26 for 150 seconds and then to the drying tank 27 for drying at 70°C for 300 seconds.

[0100] (3) Transferring the metal electrode 10 to the carrier film 11: A thermally conductive PET / POE composite film is used as the carrier film 11, with a PET thickness of 20um and a POE thickness of 5um. The POE side of the carrier film 11 is laid flat on the side of the electroforming template on which the metal electrode 10 is electroformed. After uniformly applying pressure, the carrier film 11 is infrared-heated to 80°C for 30 seconds. The metal electrode 10 is embedded in the carrier film 11, and then the metal electrolytic carrier film 11 is peeled off from the electroforming template. After the metal electrode 10 on the carrier film 11 is connected to the negative pole of a constant current power supply, it is immersed in a tin plating tank 25 to complete the tin plating of the surface of the metal electrode 10. The voltage is 1V and the current is 1A / dm 2 The electroformed template is then transferred to the third washing tank 26 for 150 seconds and then to the drying tank 27 for drying at 70°C for 300 seconds.

[0101] (4) Bonding the carrier film 11 to the cell 12: The carrier film 11 containing the metal electrode 10 is laid flat on the front and back of the solar cell, with the side of the carrier film 11 with the metal electrode 10 facing the surface of the solar cell. The secondary grid portion of the metal electrode 10 contacts the surface of the solar cell, and the main grid portion of the metal electrode 10 extends outside the solar cell. The main grid portion on the front and the main grid portion on the back are distributed on both sides of the solar cell. After the three-layer structure of carrier film 11 / solar cell / carrier film 11 is aligned, uniform pressure is applied and the carrier film 11 is infrared heated to a temperature of 130°C and a heating and extrusion time of 60 seconds.

[0102] Example 3: A method for preparing a metallized electrode for a solar cell, comprising the following steps:

[0103] (1) Preparation of electroforming template: A polished stainless steel substrate is used as the metal substrate 1, and a copper wire is welded on the back as the power line 4. The power line 4, the entire back of the metal substrate, and the edges are insulated with insulating paint. On the front of the metal substrate, a silicon nitride film with a thickness of 8 μm is deposited using a chain PVD method to form an anti-electroplating layer 2. Finally, according to the design of the electrode pattern, a UV laser with a wavelength of 355 nm is used to focus on the anti-electroplating layer 2 to remove the silicon nitride layer in the area where the metal electrode 10 is to be deposited, thus forming a conductive circuit 3.

[0104] (2) Electroforming metal electrode 10: Connect the back side of the electroforming template prepared in step (1) to the negative pole of the constant current power supply and immerse it in the first nickel plating tank 21 of the electroplating tank 6. The first nickel plating tank 21 contains nickel plating solution 7, with a voltage of 5V and a current density of 5A / dm 2 , the power-on time is 1 min, and the plating solution temperature is 25°C. After the nickel plating is completed, the electroformed template is transferred to the first water washing tank 22, and the water washing time is 100s. Next, the electroformed template is transferred to the copper plating tank 23, connected to the negative pole of the constant current power supply, the power-on voltage is 1.5V, and the power-on current density is 8A / dm 2 , the power-on time is 2min, and the plating solution temperature is room temperature. Then transfer the electroformed template to the second water washing tank 24, and the water washing time is 200s. Transfer the electroformed template to the tin plating tank 25, connect the negative pole of the constant current power supply, the power-on voltage is 1.5V, and the power-on current is 5A / dm 2 The electroformed template is then transferred to the third washing tank 26 for 200 seconds and then to the drying tank 27 for 500 seconds at a temperature of 90°C.

[0105] (3) Transferring the metal electrode 10 to the carrier film 11: A thermally conductive PET / POE composite film is used as the carrier film 11, with a PET thickness of 50um and a POE thickness of 10um. The POE material side of the carrier film 11 is laid flat on the side of the electroforming template on which the metal electrode 10 is electroformed. After uniformly applying pressure, the carrier film 11 is infrared heated to 120°C for 20 seconds. The metal electrode 10 is embedded in the carrier film 11, and then the metal electrolytic carrier film 11 is peeled off from the electroforming template. After the metal electrode 10 on the carrier film 11 is connected to the negative pole of a constant current power supply, it is immersed in a tin plating tank 25 to complete the tin plating of the surface of the metal electrode 10. The power-on voltage is 1.5V and the power-on current is 5A / dm 2 The electroformed template is then transferred to the third washing tank 26 for 200 seconds and then to the drying tank 27 for 500 seconds at a temperature of 90°C.

[0106] (4) Bonding the carrier film 11 to the cell 12: The carrier film 11 containing the metal electrode 10 is laid flat on the front and back of the solar cell, with the side of the carrier film 11 with the metal electrode 10 facing the surface of the solar cell. The secondary grid portion of the metal electrode 10 contacts the surface of the solar cell, and the main grid portion of the metal electrode 10 extends outside the solar cell. The main grid portion on the front and the main grid portion on the back are distributed on both sides of the solar cell. After the three-layer structure of carrier film 11 / solar cell / carrier film 11 is aligned, uniform pressure is applied and the carrier film 11 is infrared heated to a temperature of 160°C and a heating and extrusion time of 30 seconds.

[0107] Example 4: A method for preparing a carrier film in a metallized electrode of a solar cell, comprising the following steps:

[0108] (1) Preparation of thermal conductive filler:

[0109] S1. Weigh 1 g of aluminum nitride nanoparticles (purity ≥ 99.99%, particle size 50-60 nm), 0.36 g of γ-mercaptopropyltriethoxysilane, 15 g of ethanol, and 5 g of deionized water, mix thoroughly, and stir at 55°C for 8 h. Then, vacuum filter, wash with pure water three times, and vacuum dry to obtain thiol-modified aluminum nitride.

[0110] S2, weighing 1.36g of allyl alcohol glycidyl ether and 1.34g of 5-aminobenzotriazole, adding them to 20g of tetrahydrofuran solvent, stirring thoroughly, adding sodium hydroxide solution dropwise until the pH = 10.0, then heating to 60°C, keeping stirring for 8h, after the reaction is completed, adding dilute hydrochloric acid dropwise until the reaction solution is neutral, extracting and collecting the organic phase, and removing the solvent under reduced pressure to obtain a benzotriazole derivative;

[0111] S3. Weigh 1g of thiol-modified aluminum nitride and add it to 20g of tetrahydrofuran solvent. Ultrasonic dispersion is carried out. In an inert gas atmosphere, 0.54g of benzotriazole derivatives and 3% of the mass of benzotriazole derivatives (Irgacure 2959) are added. Place the mixture at room temperature and conduct the irradiation at 365nm and 30mW / cm 2 The product was irradiated under UV light for 60 min, separated by centrifugation, washed with ethanol three times, and dried in vacuum to obtain a thermal conductive filler.

[0112] (2) Weigh 100 parts of POE resin ENGAGE 7387 and 6 parts of thermal conductive filler and mix them evenly in a blender, then co-extrude and cast at 105°C to obtain a modified POE film;

[0113] (3) First, the Japanese Toray Lumirror UY34 PET film was corona treated with a corona value of 50 dyne. Then, the modified POE film and the PET film were laminated and hot pressed at a temperature of 165 °C, a pressure of 4 MPa, and a holding time of 8 s to obtain a thermally conductive PET / POE composite film, i.e., a carrier film.

[0114] Example 5: A method for preparing a carrier film in a metallized electrode of a solar cell, comprising the following steps:

[0115] (1) Preparation of thermal conductive filler:

[0116] S1. Weigh 1 g of aluminum nitride nanoparticles (purity ≥ 99.99%, particle size 50-60 nm), 0.24 g of γ-mercaptopropyltriethoxysilane, 10 g of ethanol, and 5 g of deionized water, mix thoroughly, and stir at 50°C for 5 h. Then, vacuum filter, wash with pure water three times, and vacuum dry to obtain thiol-modified aluminum nitride.

[0117] S2, weighing 1.25g of allyl alcohol glycidyl ether and 1.34g of 5-aminobenzotriazole, adding them to 10g of tetrahydrofuran solvent, stirring thoroughly, adding sodium hydroxide solution dropwise until the pH = 9.0, then heating to 50°C, keeping stirring for 6h, after the reaction is completed, adding dilute hydrochloric acid dropwise until the reaction solution is neutral, extracting and collecting the organic phase, and removing the solvent under reduced pressure to obtain a benzotriazole derivative;

[0118] S3. Weigh 1g of thiol-modified aluminum nitride and add it to 10g of tetrahydrofuran solvent. Ultrasonic dispersion is carried out. In an inert gas atmosphere, 0.43g of benzotriazole derivatives and 1% of the mass of benzotriazole derivatives (Irgacure 2959) are added. Place the mixture at room temperature and conduct the irradiation at 365nm and 10mW / cm 2 The product was irradiated under UV light for 90 min, separated by centrifugation, washed with ethanol three times, and dried in vacuum to obtain a thermal conductive filler.

[0119] (2) Weigh 100 parts of POE resin ENGAGE 7387 and 3 parts of thermal conductive filler and mix them evenly in a blender, then co-extrude and cast at 100°C to obtain a modified POE film;

[0120] (3) First, the Japanese Toray Lumirror UY34 PET film was corona treated with a corona value of 48 dyne. Then, the modified POE film and the PET film were laminated and hot-pressed at a temperature of 150 °C, a pressure of 3 MPa, and a holding time of 4 s to obtain a thermally conductive PET / POE composite film.

[0121] Example 6: A method for preparing a carrier film in a metallized electrode of a solar cell, comprising the following steps:

[0122] (1) Preparation of thermal conductive filler:

[0123] S1. Weigh 1 g of aluminum nitride nanoparticles (purity ≥ 99.99%, particle size 50-60 nm), 0.48 g of γ-mercaptopropyltriethoxysilane, 20 g of ethanol, and 10 g of deionized water, mix thoroughly, and stir at 60°C for 10 h. Then, vacuum filter, wash with pure water three times, and vacuum dry to obtain thiol-modified aluminum nitride.

[0124] S2, weighing 1.48g of allyl alcohol glycidyl ether and 1.34g of 5-aminobenzotriazole, adding them to 30g of tetrahydrofuran solvent, stirring thoroughly, adding sodium hydroxide solution dropwise until the pH = 10.0, then heating to 70°C, keeping stirring for 12h, after the reaction is completed, adding dilute hydrochloric acid dropwise until the reaction solution is neutral, extracting and collecting the organic phase, and removing the solvent under reduced pressure to obtain a benzotriazole derivative;

[0125] S3. Weigh 1g of thiol-modified aluminum nitride and add it to 30g of tetrahydrofuran solvent. Ultrasonic dispersion is carried out. In an inert gas atmosphere, 0.65g of benzotriazole derivatives and 5% of the mass of benzotriazole derivatives (Irgacure 2959) are added. Place the mixture at room temperature and conduct the irradiation at 365nm and 50mW / cm 2 The product was irradiated under UV light for 30 min, centrifuged, washed with ethanol three times, and vacuum dried to obtain a thermal conductive filler.

[0126] (2) Weigh 100 parts of POE resin ENGAGE 7387 and 8 parts of thermal conductive filler and mix them evenly in a blender, then co-extrude and cast at 110°C to obtain a modified POE film;

[0127] (3) First, the Japanese Toray Lumirror UY34 PET film was corona treated with a corona value of 50 dyne. Then, the modified POE film and the PET film were laminated and hot-pressed at a temperature of 175 °C, a pressure of 5 MPa, and a holding time of 10 s to obtain a thermally conductive PET / POE composite film.

[0128] Comparative Example 1

[0129] A method for preparing a metallized electrode for a solar cell comprises the following steps:

[0130] (1) Silver-coated copper conductive paste was screen-printed on the back of the HJT cell (screen parameters: 500 mesh 9μm screen wire diameter, 13μm yarn thickness, 3μm PI film thickness, 50 35μm secondary grid lines and 16 main grid lines) at a belt speed of 12000mm / min and dried at a temperature peak of 180℃ for 150s.

[0131] (2) Silver-coated copper conductive paste was screen-printed on the front side of the HJT cell with back-side grid lines (screen parameters: 500 mesh 9μm screen wire diameter, 13μm yarn thickness, 3μm PI film thickness, 80 35μm secondary grid lines and 16 main grid lines) at a belt speed of 12000mm / min and dried at a temperature peak of 180℃ for 150s.

[0132] (3) The HJT cell obtained in step (2) is placed in a curing furnace and cured in an air atmosphere at a belt speed of 12,000 mm / min, wherein the temperature peak is 200°C and the sintering time is 6 minutes, thereby completing the metallization of the HJT solar cell.

[0133] Comparative Example 2

[0134] A method for preparing a carrier film in a metallized electrode of a solar cell, which differs from Example 4 in that the thermally conductive filler is replaced with aluminum nitride nanoparticles, comprises the following steps:

[0135] (1) Weigh 100 parts of POE resin ENGAGE 7387 and 6 parts of thermal conductive filler (aluminum nitride nanoparticles) and mix them evenly in a blender, then co-extrude and cast at 105°C to obtain a modified POE film;

[0136] (2) First, the Japanese Toray Lumirror UY34 PET film was corona treated with a corona value of 50 dyne. Then, the modified POE film and the PET film were laminated and hot-pressed at a temperature of 165 °C, a pressure of 4 MPa, and a holding time of 8 s to obtain a thermally conductive PET / POE composite film, i.e., a carrier film.

[0137] Comparative Example 3

[0138] A method for preparing a carrier film in a metallized electrode of a solar cell, which differs from Example 4 in that the preparation process of the thermally conductive filler is different, comprises the following steps:

[0139] (1) Preparation of thermal conductive filler:

[0140] S1. Weigh 1 g of aluminum nitride nanoparticles (purity ≥ 99.99%, particle size 50-60 nm), 0.36 g of γ-mercaptopropyltriethoxysilane, 15 g of ethanol, and 5 g of deionized water, mix thoroughly, and stir at 55°C for 8 h. Then, vacuum filter, wash with pure water three times, and vacuum dry to obtain thiol-modified aluminum nitride.

[0141] S2. Weigh 1 g of thiol-modified aluminum nitride and add it to 20 g of tetrahydrofuran solvent. Ultrasonic dispersion is carried out, and 1.34 g of 5-aminobenzotriazole is added. After sufficient stirring, sodium hydroxide solution is added dropwise until the pH is 10.0. The temperature is then raised to 60° C. and stirred for 8 h. After the reaction is completed, dilute hydrochloric acid is added dropwise until the reaction solution becomes neutral. The organic phase is extracted and collected, and the solvent is removed under reduced pressure to obtain a thermally conductive filler.

[0142] (2) Weigh 100 parts of POE resin ENGAGE 7387 and 6 parts of thermal conductive filler (aluminum nitride nanoparticles) and mix them evenly in a blender, then co-extrude and cast at 105°C to obtain a modified POE film;

[0143] (3) First, the Japanese Toray Lumirror UY34 PET film was corona treated with a corona value of 50 dyne. Then, the modified POE film and the PET film were laminated and hot pressed at a temperature of 165 °C, a pressure of 4 MPa, and a holding time of 8 s to obtain a thermally conductive PET / POE composite film, i.e., a carrier film.

[0144] Experimental Example 1

[0145] The metal electrode prepared in Example 1 was applied to a solar cell to test the conversion efficiency. Compared with the traditional screen-printed silver electrode in Comparative Example 1, the results are shown in Table 1 below:

[0146] Table 1 Comparison of solar cell test parameters

[0147] Group Conversion efficiency (Eff) Open circuit voltage (Voc) Short-circuit current (Isc) Fill Factor (FF) Example 1 0.09% 0.00 0.016 -0.08 Comparative Example 1 0* 0* 0* 0*

[0148] Note: 0* means that this is the reference, i.e. the result of Example 1 is the change value based on Comparative Example 1.

[0149] From Table 1 and Figure 7-10 As can be seen from the figure, solar cells metallized with the metal electrodes of the present invention exhibit smoother surfaces and a gain in short-circuit current. This demonstrates that electroformed metal electrodes block less light and reduce high-frequency signal loss, leading to improved efficiency. More importantly, the metal electrodes of the present invention include nickel, copper, and tin—all base metals—without precious silver, significantly reducing material costs.

[0150] Experimental Example 2

[0151] The performance of the carrier membranes prepared in Example 4 was compared with that in Comparative Examples 2-3, and the results are shown in Table 2 below:

[0152] Table 2 Comparison of battery carrier membrane performance

[0153] Group Tensile strength (MPa) Peel strength (N / 15mm) Thermal conductivity (W / (m·K)) Light transmittance (%) After UV treatment, yellowing index (ΔYi) After UV treatment, light transmittance retention rate (%) Longitudinal shrinkage (%) Example 4 52.7 48 2.1 91.3 2.0 95.2 0.22 Comparative Example 2 43.5 40 2.2 88.9 3.1 89.7 0.47 Comparative Example 3 48.1 45 2.0 91.0 2.4 92.3 0.28

[0154] Tensile strength refers to GB / T 13542.2-2009; peel strength refers to GB / T 2790-1995; dimensional stability refers to GB / T 12027-2004; thermal conductivity refers to ASTM D5470; light transmittance refers to GB / T 2410-2008; UV treatment parameters: UVA-340 lamp, irradiation intensity 0.76 W / m 2 , cycle 240 hours, yellowing index refers to GB / T 2409-2008, UV transmittance retention refers to GB / T 16422.3-2014.

[0155] As can be seen from Table 2, the carrier film prepared in Example 4 of the present invention has higher strength and performs better in terms of interfacial adhesion, light stability, and stability. This shows that the carrier film prepared in the present invention not only maintains light transmittance and thermal conductivity, but also enhances mechanical strength and stability, and also exhibits excellent aging resistance.

[0156] 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 the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a metallized electrode for a solar cell, characterized in that: The following steps are involved: Step 1: Preparation of electroforming template: One side of the polished metal substrate is welded with a power circuit and coated with an insulating layer, and then a resist layer is deposited. After that, part of the resist layer is etched according to the electrode pattern to form a conductive circuit; Step 2: Electroforming metal electrodes: Prepare an electroplating solution, immerse the electroformed template obtained in the first step as a cathode in the electroplating solution, and connect the side with the conductive circuit to an external power supply. Apply power to perform electroforming, wash, and dry to obtain an electroformed metal electrode. Step 3: Transfer the metal electrode to the carrier film: A carrier film is prepared and stretched to cover the electrode surface. The film is heated and pressurized to embed the film into the side where the electroformed metal electrode is deposited. After cooling, the carrier film and the metal electrode are peeled off. The peeled carrier film and the metal electrode are then subjected to secondary electroplating to obtain a carrier film embedded with the metal electrode. Step 4: Combining the carrier film with the solar cell: The carrier film embedded with the metal electrode is laminated and packaged with the solar cell, wherein the side of the carrier film with the metal electrode faces the surface of the solar cell. After fixing, the metallized electrode of the solar cell is obtained.

2. The method for preparing a metallized electrode for a solar cell according to claim 1, wherein: In step 1, the metal substrate is an alloy of one or more metals selected from the group consisting of copper, aluminum, titanium, and nickel; the anti-electroplating layer is a combination of one or more selected from the group consisting of silicon nitride, aluminum oxide, silicon oxide, polyimide, polytetrafluoroethylene, and epoxy resin; the conductive circuit is an exposed area of ​​the metal substrate formed by removing part of the anti-electroplating layer through a laser etching or photoresist etching process; and the power supply circuit is a copper wire, an aluminum wire, or an iron wire.

3. The method for preparing a metallized electrode for a solar cell according to claim 1, wherein: In step 2, the electroplating solution is one or more combinations of electroplating solutions of nickel, copper, tin, copper-tin alloy, and tin-nickel alloy.

4. The method for preparing a metallized electrode for a solar cell according to claim 1, wherein: In step 2, the voltage of the DC power supply during electroforming is 0.3~10V, and the current density is 0.1~10A / dm 2 , the electroforming time is 1~15min.

5. The method for preparing a metallized electrode for a solar cell according to claim 1, wherein: In step 2 and step 3, the secondary electroplating is to connect the peeled carrier film together with the metal electrode to the negative pole of a DC power supply and immerse them in a tin electroplating tank to complete the tin electroplating.

6. The method for preparing a metallized electrode for a solar cell according to claim 1, wherein: In step 4, the lamination is performed by aligning the three-layer structure of carrier film / solar cell / carrier film, feeding the structure into the laminating equipment, applying uniform pressure to the carrier film and the solar cell, and heating the structure at a temperature of 130-160° C. for a pressing time of 10-120 seconds.

7. The method for preparing a metallized electrode for a solar cell according to claim 1, wherein: In step 3, the carrier film is a thermally conductive PET / POE composite film, and the preparation method includes: (1) Weighing POE resin and thermal conductive filler and mixing them evenly in a blender, wherein the weight ratio of POE resin to thermal conductive filler is 100:2-10, and then co-extruding and casting at 100-110°C to obtain a modified POE film; (2) The PET film was first subjected to corona treatment, and then the modified POE film and the PET film were laminated and hot pressed at a temperature of 150-175°C, a pressure of 3-5 MPa, and a holding time of 4-10 s to obtain a thermally conductive PET / POE composite film.

8. The method for preparing a metallized electrode for a solar cell according to claim 7, wherein: In step 3, the thickness of the PET film layer is 10-50 μm, and the thickness of the modified POE film layer is 5-10 μm.

9. The method for preparing a metallized electrode for a solar cell according to claim 7, wherein: The preparation method of the thermally conductive filler comprises: S1. Weigh aluminum nitride nanoparticles, γ-mercaptopropyltriethoxysilane, ethanol, and deionized water, mix thoroughly, and stir at 50-60°C for 5-10 hours. Then, vacuum filter, wash with pure water three times, and vacuum dry to obtain mercapto-modified aluminum nitride. S2. Weigh allyl alcohol glycidyl ether and 5-aminobenzotriazole, add them to tetrahydrofuran solvent, stir thoroughly, adjust the pH to 9.0-10.0, then heat to 50-70° C., keep stirring for 6-12 hours. After the reaction is completed, adjust the reaction solution to neutral, extract and collect the organic phase, and remove the solvent under reduced pressure to obtain a benzotriazole derivative; S3. Weigh the thiol-modified aluminum nitride and add it to the solvent tetrahydrofuran, disperse it evenly by ultrasonication, add benzotriazole derivatives and photoinitiator in an inert gas atmosphere, place it at room temperature, irradiate it under UV light, separate the product by centrifugation, wash it with ethanol three times, and vacuum dry it to obtain a thermally conductive filler.

10. A metallized electrode for a solar cell, prepared by the preparation method according to claim 1.

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