Solar cell metalized electrode and preparation method thereof

Abstract

The invention relates to the field of solar cells, in particular to a solar cell metalized electrode and a preparation method thereof. The preparation method of the metallized electrode of the solar cell comprises the following steps: step 1, preparing an electroforming template; 2, electroforming a metal electrode; step 3, transferring the metal electrode to the carrier film; and 4, combining the carrier film with the solar cell. According to the invention, the metal electrode is combined with the assembly packaging technology, so that the strength and flexibility of the solar cell can be greatly improved, and the fragmentation risk in the production and assembly process is reduced. Meanwhile, by improving the material of the packaging adhesive film, the heat-conducting property of the packaging adhesive film is improved, the temperature of the solar cell panel assembly is reduced, and the service life of the solar cell panel assembly is prolonged.

Description

Technical Field

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

[0002] Solar cells convert sunlight directly into electricity and are a clean, renewable energy technology. Its popularity will help reduce dependence on fossil fuels, reduce greenhouse gas emissions, promote the global transition to a low-carbon economy, and address climate change challenges. The metallization technology of solar cells is one of the determining factors for the conversion efficiency of solar cells. The current mainstream metallization technology uses a screen-printed silver paste solution. That is, the silver paste is printed on the front and back of the silicon wafer by screen printing to form an electrode pattern, and then the silver electrode is formed by high-temperature sintering or low-temperature curing treatment, so that the photocurrent inside the battery can be led to the external circuit. Although the screen printing process is mature and simple, about 90% of the silver paste is silver powder particles, which makes it difficult to continuously reduce the processing cost of the battery. Silver is a precious metal with high prices and limited global reserves. As the scale of the photovoltaic industry continues to expand, the supply and cost control of silver paste raw materials are facing tremendous pressure. Therefore, it is of great significance to the solar cell industry to develop new metallization technologies to replace the screen printing silver paste solution, reduce dependence on precious metals, and further reduce the cost of power generation.

[0003] In addition, as the cost of photovoltaic power generation continues to decline, photovoltaic power generation as a new economical power generation method will accelerate the replacement of other traditional fossil energy power generation methods. However, solar panel components will generate a lot of heat during the power generation process. If the generated heat is not discharged in time, the temperature of the solar panel components will continue to rise, thereby affecting the photoelectric conversion efficiency of the solar panel components and the service life of the solar panel components. Therefore, it is particularly important to reduce the temperature of the solar panel components and improve the thermal conductivity of the components themselves. Summary of the invention

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

[0005] The purpose of the present invention is achieved by the following technical solutions: In a first aspect, the present invention provides a method for preparing a metallized electrode of a solar cell, comprising the following steps: 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 an anti-plating layer is deposited, and then a part of the anti-plating layer is etched according to the electrode pattern; Step 2: Electroforming metal electrodes: Prepare an electroplating solution, immerse the electroforming template obtained in the first step as the cathode in the electroplating solution, and at the same time connect the side with the conductive circuit to an external power supply. Conduct electroforming by applying electricity, wash and dry to obtain an electroformed metal electrode. Step 3: Transfer the metal electrode to the carrier film: Prepare a carrier film, stretch the carrier film to cover the electrode surface, heat and press to embed the film into the side where the electroformed metal electrode is deposited. After cooling, peel off the carrier film and the metal electrode, and then perform secondary electroplating on the peeled carrier film together with the metal electrode to obtain a carrier film with a metal electrode embedded therein. Step 4: Combine the carrier film with the solar cell: Laminating and encapsulating the carrier film with the embedded metal electrode and the cell sheet to complete the fixation, thus obtaining the metallized electrode of the solar cell.

[0006] Preferably, in the step 1, the electroforming template is composed of a metal substrate, an anti-electroplating layer, a conductive circuit, a power-on circuit and an insulating layer.

[0007] Preferably, in the step 1, the metal substrate is an alloy formed by one or more of copper, aluminum, titanium, and nickel. The alloy is processed by casting and rolling to form a metal sheet or a flexible metal strip (foil).

[0008] Preferably, in the step 1, the anti-electroplating layer is a combination of one or more of silicon nitride, aluminum oxide, silicon oxide, polyimide, polytetrafluoroethylene, and epoxy resin.

[0009] More preferably, the thickness of the anti-electroplating layer is 50 nm to 10 μm.

[0010] Preferably, in the step 1, the conductive circuit is an area where the metal substrate is exposed by removing part of the anti-electroplating layer through a laser etching or photoresist etching process.

[0011] Preferably, in the step 1, the power-on circuit is one of copper wire, aluminum wire, and iron wire.

[0012] Preferably, in the step 1, the insulating layer is obtained by coating with an insulating paint.

[0013] Preferably, in the step 1, the etching process is laser etching or photoresist etching.

[0014] More preferably, the etching process is to use ultraviolet laser with a wavelength of 355 nm or green laser with a wavelength of 532 nm to focus and irradiate the anti-electroplating layer according to the electrode pattern to remove part of the anti-electroplating layer area to form an exposed metal substrate.

[0015] Preferably, in the step 2, the electroplating solution is one or a combination of two or more of the electroplating solutions for electroplating nickel, electroplating copper, electroplating tin, electroplating copper-tin alloy, and electroplating tin-nickel alloy.

[0016] Preferably, in the step 2, the electroplating template is wholly immersed below the liquid level of the electroplating solution. The electroforming template is connected to the negative pole of an external DC power supply through the energizing circuit on the back, and the electroplating anode is connected to the positive pole of the external DC power supply.

[0017] Preferably, in the step 2, during electroforming, the voltage of the DC power supply is 0.3 - 10 V, the current density is 0.1 - 10 A / dm 2 , and the electroforming time is 1 - 15 min.

[0018] Preferably, in the step 2, when multi-layer electroplating is required, the operations in the step 2 are repeated successively.

[0019] Preferably, in the step 2, washing is to rinse the excess electroplating solution on the electroforming template with pure water, and drying is to dry the electroforming template. The drying time is 100 - 600 s, and the drying temperature is 50 - 95 °C.

[0020] Preferably, in the step 3, for secondary electroplating, the peeled carrier film together with the metal electrode is connected to the negative pole of the DC power supply and immersed in a tin electroplating bath to complete tin electroplating.

[0021] Preferably, in the step 3, after secondary electroplating, washing and drying are also required. Washing is to clean the carrier film together with the metal electrode after tin electroplating with pure water, and the cleaning time is 60 - 300 s; drying is to dry the cleaned carrier film together with the metal electrode. The drying temperature is 50 - 70 °C, and the drying time is 60 - 300 s.

[0022] Preferably, in the step 4, the carrier film embedded with the metal electrode is laid flat on the front and back of the battery cell, and the side of the carrier film with the metal electrode faces the surface of the solar cell.

[0023] Preferably, in the step 4, lamination is to align the three-layer structure of carrier film / solar cell / carrier film, send it into the lamination equipment, apply uniform pressure to the carrier film and the battery cell, and heat simultaneously. The heating temperature is 130 - 160 °C, and the pressure application time is 10 - 120 s.

[0024] Preferably, in the step 3, the carrier film is a heat-conductive PET / POE composite film, and the preparation method includes: (1) Weigh POE resin (polyolefin elastomer) and heat-conductive filler and mix them evenly in a blender. The weight ratio of POE resin to heat-conductive filler is 100:2 - 10, and then co-extrude and cast at 100 - 110 °C to obtain a modified POE film; (2) First, the PET film (polyethylene terephthalate) is subjected to corona treatment, and then the modified POE film and the PET film are bonded and hot-pressed to each other at a hot-pressing temperature of 150 - 175 °C, a pressure of 3 - 5 MPa, and a holding pressure time of 4 - 10 s to obtain a thermally conductive PET / POE composite film.

[0025] 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.

[0026] Preferably, the preparation method of the thermally conductive filler includes: S1. Weigh aluminum nitride nanoparticles, γ-mercaptopropyltriethoxysilane, ethanol, and deionized water and mix them. After fully mixing evenly, stir at 50 - 60 °C for 5 - 10 h, then carry out vacuum filtration, wash with pure water 3 times, and vacuum dry to obtain mercapto-modified aluminum nitride. S2. Weigh allyl glycidyl ether and 5-aminobenzotriazole and add them to the solvent tetrahydrofuran. After fully stirring, adjust the pH to 9.0 - 10.0, then raise the temperature to 50 - 70 °C, keep stirring for 6 - 12 h. After the reaction ends, 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 mercapto-modified aluminum nitride and add it to the solvent tetrahydrofuran. Ultrasonically disperse it evenly. In an inert gas atmosphere, add the benzotriazole derivative and a photoinitiator, place it in a room temperature environment, irradiate it under UV light, centrifuge and separate the product, wash it with ethanol 3 times, and vacuum dry to obtain the thermally conductive filler.

[0027] Preferably, in S1, the purity of the aluminum nitride nanoparticles is ≥99.99%, and the particle size is 50 - 60 nm.

[0028] Preferably, in S1, the mass ratio of the aluminum nitride nanoparticles, γ-mercaptopropyltriethoxysilane, ethanol, and deionized water is 1:0.24 - 0.48:10 - 20:5 - 10.

[0029] Preferably, in S2, the mass ratio of allyl glycidyl ether, 5-aminobenzotriazole, and tetrahydrofuran is 1.25 - 1.48:1.34:10 - 30.

[0030] Preferably, in S3, the mass ratio of the mercapto-modified aluminum nitride, the benzotriazole derivative, and tetrahydrofuran is 1:0.43 - 0.65:10 - 30.

[0031] Preferably, in S3, the parameters of the UV light include: 365 nm, 10 - 50 mW / cm 2 , and the irradiation time is 30 - 90 min.

[0032] Preferably, in S3, the photoinitiator is Irgacure 2959, and the added mass is 1% - 5% of the mass of the benzotriazole derivative.

[0033] In a second aspect, the present invention provides a metallized electrode for a solar cell, which is prepared by the above preparation method.

[0034] The beneficial effects of the present invention are as follows: 1. Compared with the traditional screen-printed silver paste sintered electrode of a solar cell, the present invention has a silver consumption reduction of more than 80% significantly. In particular, the silver consumption in heterojunction (HJT) cells, perovskite cells (PSC), and copper indium gallium selenide cells (CIGS) is zero, reducing the dependence of the solar cell metallization process on precious metals. At the same time, the electroformed metal electrode is closer to the intrinsic conductivity of the metal, denser than the sintered metal electrode, and has a lower resistivity, which is beneficial to reducing the conduction resistance and improving the conversion efficiency of the solar cell.

[0035] 2. By combining the metal electrode with the component encapsulation process, the present invention can greatly increase the strength and flexibility of the solar cell, reducing the risk of fragmentation during the production and assembly process. At the same time, by improving the material of the encapsulation film, the thermal conductivity of the encapsulation film is improved, the temperature of the solar cell panel assembly is reduced, and the service life of the solar cell panel assembly is extended.

[0036] 3. The present invention uses a thermally conductive PET / POE composite film as the carrier film, that is, a film obtained by composite extrusion of a modified POE material and a PET substrate. The carrier film with good thermal performance can dissipate the generated heat faster, avoiding local overheating of the battery and protecting the battery from thermal damage. On the basis of ensuring the light transmittance and thermal conductivity, the mechanical strength and stability are enhanced, and the anti-aging property is also excellent.

[0037] 4. Among them, the modified POE material is a POE resin modified by introducing a thermally conductive filler. The thermally conductive filler is a product obtained by combining mercapto-modified aluminum nitride particles and a benzotriazole derivative through a click reaction of mercapto and double bonds. Among them, the benzotriazole derivative is obtained by the ring-opening reaction of 5-aminobenzotriazole and allyl glycidyl ether, and the obtained benzotriazole derivative contains both an unsaturated double bond and a benzotriazole group. The thermally conductive filler endows the carrier film material with better interfacial adhesion, light stability, and dimensional stability through the synergistic effect of its surface functional groups (such as thioether, imine, and benzotriazole, etc.), especially the light stability is more excellent. Description of the Drawings

[0038] The present invention will be further described with reference to the accompanying drawings. However, the embodiments in the drawings do not constitute any limitation to the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the following drawings without creative efforts.

[0039] Figure 1 It is a schematic structural view of the electroforming template of the present invention deposited in the electroplating bath; Figure 2 It is a schematic structural view of the combination of the metal electrode and the solar cell of the present invention; Figure 3 It is a schematic process view of nickel plating, copper plating and tin plating of the metal electrode of the present invention; Figure 4 It is a schematic structural view of the electroforming template of the present invention; Figure 5 It is a schematic view of the metal electrode of the present invention embedded in the carrier film; Figure 6 It is a schematic view of the series structure of the components of the solar cell combined with the metal electrode film of the present invention; Figure 7 It is a SEM schematic view of the electroformed metal electrode of Example 1 of the present invention; Figure 8 It is a SEM schematic view of the metal electrode prepared by screen printing silver-coated copper paste in Comparative Example 1 of the present invention; Figure 9 It is a 3D microscope view of the electroformed metal electrode of Example 1 of the present invention embedded in the carrier film; Figure 10 It is a 3D microscope view of the metal electrode prepared by screen printing silver-coated copper paste in Comparative Example 1 of the present invention.

[0040] Reference numerals: 1 - metal substrate, 2 - anti-electroplating layer, 3 - conductive circuit, 4 - energizing circuit, 5 - insulating layer, 6 - electroplating bath, 7 - electroplating solution, 8 - electroplating anode plate, 9 - DC power supply, 10 - metal electrode, 11 - carrier film, 12 - cell; 21 - nickel plating bath, 22 - first water washing bath, 23 - copper plating bath, 24 - second water washing bath, 25 - tin plating bath, 26 - third water washing bath, 27 - drying bath. Detailed Embodiments

[0041] In order to illustrate the present invention more clearly and have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solutions of the present invention will be described in detail below, but it should not be construed as a limitation on the scope of implementation of the present invention.

[0042] In the following embodiments, the raw materials, reagents or devices used can be obtained from conventional commercial channels or can be obtained by known existing methods without special instructions.

[0043] The present invention will be further described in conjunction with the following embodiments.

[0044] A method for preparing a metallized electrode of a solar cell, comprising the following steps: First step, electroforming template preparation: (1) Installation and insulation treatment of the energized circuit 4: One side of the polished metal substrate 1 is welded with the energized circuit 4, and the insulation layer 5 is coated.

[0045] (2) Deposition of the anti-electroplating layer 2: A anti-electroplating layer 2 with a thickness of 50 nm to 10 μm is deposited 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.

[0046] (3) Opening the anti-electroplating layer 2: Using ultraviolet laser with a wavelength of 355 nm or green laser with a wavelength of 532 nm, the focused irradiation removes the anti-electroplating layer 2 in some areas, and forms a bare metal substrate 1 surface area according to the electrode pattern, forming the conductive circuit 3.

[0047] Second step, metal electrode 10: (1) Preparation of the electroplating solution 7: The electroplating solution uses commercial electroplating solutions 7 for nickel plating, copper plating, and tin plating and electroplating anode plates 8. The above electroplating solutions are respectively poured into the nickel plating tank 21, copper plating tank 23, and tin plating tank 25 for nickel plating, copper plating, and tin plating and are ready for use; (2) Immerse the electroforming template as the cathode into the nickel plating tank 21 prepared in step (1). The electroforming template is entirely immersed below the liquid level of the electroplating solution. The electroforming template is connected to the negative pole of the external DC power supply 9 through the energized circuit 4 on the back, and the electroplating anode is connected to the positive pole of the external DC power supply 9.

[0048] (3) Energized electroforming: The voltage of the DC power supply 9 is 0.3 to 10 V, the current density is 0.1 to 10 A / dm 2 , and the electroforming time is 1 to 15 minutes; (4) Water washing: The electroforming template is taken out of the nickel plating tank 21, and the excess electroplating solution on the electroforming template is rinsed off with pure water to complete the deposition of the nickel layer; (5) Sequentially repeat steps (2), (3), and (4) to complete the deposition of the copper and tin layers in the copper plating tank 23 and the tin plating tank 25 respectively.

[0049] (6) Drying: The electroforming template is dried, the drying time is 100 to 600 s, and the drying temperature is 50 to 95 °C.

[0050] Third step, transferring the metal electrode 10 to the carrier film 11: (1) Preparation of the carrier film 11: The carrier film 11 is obtained by compound extrusion of a modified POE material and a PET substrate.

[0051] (2) Coating of 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.

[0052] (3) Lamination treatment: For the electroforming template and the carrier film 11 laid flat in step (2), apply uniform pressure and heat to 75 - 120 °C simultaneously, so that the carrier film 11 slightly melts and the metal electrode 10 embeds into the carrier film 11.

[0053] (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 is peeled off from the electroforming template.

[0054] (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 bath 25 to complete tin electroplating.

[0055] (6) Wash the carrier film 11 together with the metal electrode 10 after tin plating in step (5) with pure water. The washing time is 60 - 300 s.

[0056] (7) Dry the carrier film 11 together with the metal electrode 10 after washing in step (6). The drying temperature is 50 - 70 °C and the drying time is 60 - 300 s.

[0057] Fourth step, combination of the carrier film 11 and the solar cell: (1) The carrier film 11 inlaid with the metal electrode 10 is laid flat on the front and back of the cell 12, and the side of the carrier film 11 with the metal electrode 10 faces the surface of the solar cell.

[0058] (2) After completing step (1), send it into the lamination equipment, apply uniform pressure to the carrier film 11 and the cell 12, and heat simultaneously. The heating temperature is 130 - 160 °C and the pressure application time is 10 - 120 s.

[0059] (3) After completing step (2), the cell 12, the carrier film 11 and the metal electrode 10 are encapsulated.

[0060] Example 1: A method for preparing a metallized electrode of a solar cell, comprising the following steps: (1) Preparation of the electroforming template: Use a stainless - steel material with a polished surface as the metal substrate 1, weld copper wires on the back as the power - on circuit 4, and insulate the power - on circuit 4, the entire back surface of the metal substrate, and the four - week edges with insulating paint. On the front surface of the metal substrate, deposit a silicon nitride film layer with a thickness of 5 μm by the chain - type PVD method to form the anti - plating layer 2. Finally, according to the design of the electrode pattern, use ultraviolet laser with a wavelength of 355 nm to focus and irradiate the anti - plating layer 2 to remove the silicon nitride layer in the area where the metal electrode 10 needs to be deposited, thus forming the conductive circuit 3.

[0061] (2) Electroformed metal electrode 10: Connect the negative electrode of the regulated constant current power supply to the back power supply circuit 4 of the electroforming template made in step (1), and immerse it into the first nickel plating tank 21 of the electroplating tank 6. The nickel plating solution 7 is in the first nickel plating tank 21, the applied voltage is 3V, and the current density is 3A / dm 2 , the electrolysis time is 3 min, and the solution temperature is 30 °C. After the nickel coating is completed, the electroforming template is transferred to the first water washing tank 22, and the water washing time is 100 s. Next, the electroforming template is transferred to the copper plating tank 23, connect the negative electrode of the regulated constant current power supply, the applied voltage is 0.8V, and the current density is 5A / dm 2 , the electrolysis time is 3 min, and the solution temperature is at room temperature. Then transfer the electroforming template to the second water washing tank 24, and the water washing time is 100 s. Transfer the electroforming template to the tin plating tank 25, connect the negative electrode of the regulated constant current power supply, the applied voltage is 0.8V, and the current is 3A / dm 2 , the electrolysis time is 1.5 min. Next, the electroforming template is transferred to the third water washing tank 26 for 100 s of water washing. Then it is transferred to the drying tank 27 for drying, the drying time is 500 s, and the drying temperature is 75 °C.

[0062] (3) Transfer the metal electrode 10 to the carrier film 11: Use a thermally conductive PET / POE composite film as the carrier film 11 (prepared as in Example 4), the thickness of the PET layer is 30 μm, and the thickness of the POE layer is 8 μm. The POE side of the carrier film 11 is laid flat on one side of the electroforming template electroformed with the metal electrode 10. After uniformly applying pressure, the carrier film 11 is heated by infrared to 110 °C at the same time, and the heating time is 40 s. Let the metal electrode 10 be embedded in the carrier film 11, and then peel off the carrier film 11 containing the metal electrolysis carrier film from the electroforming template. After connecting the negative electrode of the regulated constant current power supply to the metal electrode 10 on the carrier film 11, immerse it into the tin plating tank 25 to complete the tin plating on the surface of the metal electrode 10, the applied voltage is 0.8V, and the current is 3A / dm 2 , the electrolysis time is 1.5 min. Next, the electroforming template is transferred to the water washing tank for 100 s of water washing. Then it is transferred to the drying tank for drying, the drying time is 500 s, and the drying temperature is 75 °C.

[0063] (4) Bonding of the carrier film 11 to the solar cell 12: The carrier film 11 containing the metal electrode 10 is laid flat on the front and back of the solar cell. The side of the carrier film 11 with the metal electrode 10 faces the surface of the solar cell. The sub-grid part of the metal electrode 10 is in contact with the surface of the solar cell, and the main-grid part of the metal electrode 10 extends outside the solar cell. The main-grid parts on the front and 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 heated by infrared, with the heating temperature being 150 °C and the heating and extrusion time being 80 s.

[0064] Example 2: A method for preparing a metallized electrode of a solar cell, comprising the following steps: (1) Preparation of the electroforming template: A stainless steel material with a polished surface is used as the metal substrate 1, and a copper wire is welded to the back as the power supply line 4. The power supply line 4, the entire back surface of the metal substrate, and the four peripheral edges are insulated with insulating paint. On the front surface of the metal substrate, a silicon nitride film layer with a thickness of 2 μm is deposited by the 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 and irradiate the anti-electroplating layer 2 to remove the silicon nitride layer in the area where the metal electrode 10 needs to be deposited, thereby forming the conductive line 3.

[0065] (2) Electroforming the metal electrode 10: The power supply line 4 on the back of the electroforming template made in step (1) is connected to the negative pole of a regulated constant current power supply and immersed in the first nickel plating tank 21 of the electroplating tank 6. The first nickel plating tank 21 contains a nickel electroplating solution 7, with a power supply voltage of 3 V, a power supply current density of 1 A / dm 2 , a power supply time of 5 min, and a plating solution temperature of 35 °C. After the nickel plating layer is completed, the electroforming template is transferred to the first water washing tank 22, and the water washing time is 150 s. Next, the electroforming template is transferred to the copper plating tank 23, connected to the negative pole of the regulated constant current power supply, with a power supply voltage of 0.5 V, a power supply current density of 3 A / dm 2 , a power supply time of 5 min, and a plating solution temperature at room temperature. Then the electroforming template is transferred to the second water washing tank 24, and the water washing time is 150 s. The electroforming template is transferred to the tin plating tank 25, connected to the negative pole of the regulated constant current power supply, with a power supply voltage of 1 V and a power supply current of 1 A / dm 2 , a power supply time of 2 min. Next, the electroforming template is transferred to the third water washing tank 26 for water washing for 150 s. Then it is transferred to the drying tank 27 for drying, with a drying time of 300 s and a drying temperature of 70 °C.

[0066] (3) Transfer of the metal electrode 10 to the carrier film 11: Use a thermally conductive PET / POE composite film as the carrier film 11, with the PET having a thickness of 20 μm and the POE having a thickness of 5 μm. The POE side of the carrier film 11 is laid flat on one side of the electroforming template electroformed with the metal electrode 10. After applying pressure evenly and simultaneously heating the carrier film 11 with infrared rays to 80 °C for 30 s, the metal electrode 10 is embedded into the carrier film 11, and then the carrier film 11 containing the metal electrolytic carrier is peeled off from the electroforming template. After the metal electrode 10 on the carrier film 11 is connected to the negative electrode of a regulated constant-current power supply, it is immersed in a tin plating bath 25 to complete tin plating on the surface of the metal electrode 10. The energization voltage is 1 V, and the energization current is 1 A / dm 2 , and the energization time is 2 min. Next, the electroforming template is transferred to a third water washing tank 26 for water washing for 150 s. Then it is transferred to a drying tank 27 for drying. The drying time is 300 s, and the drying temperature is 70 °C.

[0067] (4) Bonding of the carrier film 11 with the battery chip 12: The carrier film 11 containing the metal electrode 10 is laid flat on the front and back of the solar cell. Among them, the side of the carrier film 11 with the metal electrode 10 faces the surface of the solar cell. The sub-grid part of the metal electrode 10 is in contact with the surface of the solar cell, and the main-grid part of the metal electrode 10 extends outside the solar cell. The main-grid parts on the front and back are distributed on both sides of the solar cell. After the three-layer structure of the carrier film 11 / solar cell / carrier film 11 is aligned, apply uniform pressure and heat the carrier film 11 with infrared rays. The heating temperature is 130 °C, and the heating and extrusion time is 60 s.

[0068] Example 3: A method for preparing a metallized electrode of a solar cell, comprising the following steps: (1) Preparation of the electroforming template: Use a stainless steel material with a polished surface as the metal substrate 1, weld a copper wire on the back as the energization circuit 4, and insulate the energization circuit 4, the entire back surface of the metal substrate, and the four peripheral edges with an insulating paint. On the front surface of the metal substrate, deposit a silicon nitride film layer with a thickness of 8 μm by means of chain PVD to form an anti-electroplating layer 2. Finally, according to the design of the electrode pattern, use ultraviolet laser with a wavelength of 355 nm to focus and irradiate the anti-electroplating layer 2 to remove the silicon nitride layer in the area where the metal electrode 10 needs to be deposited, that is, to form the conductive circuit 3.

[0069] (2) Electroforming the metal electrode 10: Connect the energization circuit 4 on the back of the electroforming template made in step (1) to the negative electrode of a regulated 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 a nickel-nickel plating solution 7. The energization voltage is 5 V, and the energization current density is 5 A / dm 2, The power-on time is 1 min and the plating solution temperature is 25°C. After the nickel plating layer is completed, the electroforming template is transferred to the first water washing tank 22, and the water washing time is 100 s. Next, the electroforming template is transferred to the copper plating tank 23, connected to the negative pole of a regulated constant current power supply, the power-on voltage is 1.5 V, and the power-on current density is 8 A / dm 2 , The power-on time is 2 min and the plating solution temperature is at room temperature. Then the electroforming template is transferred to the second water washing tank 24, and the water washing time is 200 s. The electroforming template is transferred to the tin plating tank 25, connected to the negative pole of a regulated constant current power supply, the power-on voltage is 1.5 V, and the power-on current is 5 A / dm 2 , The power-on time is 0.5 min. Next, the electroforming template is transferred to the third water washing tank 26 for water washing for 200 s. Then it is transferred to the drying tank 27 for drying, the drying time is 500 s, and the drying temperature is 90°C.

[0070] (3) Transfer of the metal electrode 10 to the carrier film 11: Use a thermally conductive PET / POE composite film as the carrier film 11, with a PET thickness of 50 μm and a POE thickness of 10 μm. The side of the carrier film 11 made of POE is laid flat on one side of the electroforming template electroformed with the metal electrode 10. After uniformly applying pressure, the carrier film 11 is simultaneously heated by infrared to 120°C for 20 s. Let the metal electrode 10 be embedded in the carrier film 11, and then the carrier film 11 containing the metal electrolytic carrier film 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 regulated constant current power supply, it is immersed in the tin plating tank 25 to complete the tin plating on the surface of the metal electrode 10, the power-on voltage is 1.5 V, and the power-on current is 5 A / dm 2 , The power-on time is 0.5 min. Next, the electroforming template is transferred to the third water washing tank 26 for water washing for 200 s. Then it is transferred to the drying tank 27 for drying, the drying time is 500 s, and the drying temperature is 90°C.

[0071] (4) Bonding of the carrier film 11 with the battery chip 12: Lay the carrier film 11 containing the metal electrode 10 on the front and back of the solar cell. Among them, the side of the carrier film 11 with the metal electrode 10 faces the surface of the solar cell. The sub-grid part of the metal electrode 10 is in contact with the surface of the solar cell, and the main-grid part of the metal electrode 10 extends outside the solar cell. The main-grid parts on the front and back are distributed on both sides of the solar cell. After the three-layer structure of the carrier film 11 / solar cell / carrier film 11 is aligned, apply uniform pressure and heat the carrier film 11 by infrared, the heating temperature is 160°C; the heating and extrusion time is 30 s.

[0072] Example 4: A method for preparing a carrier film in a metallized electrode of a solar cell, comprising the following steps: (1) Preparation of thermally conductive filler: 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 them thoroughly, stir at 55 °C for 8 h, then perform vacuum filtration, wash with pure water 3 times, and dry under vacuum to obtain mercapto-modified aluminum nitride; S2. Weigh 1.36 g of allyl glycidyl ether and 1.34 g of 5-aminobenzotriazole, add them to 20 g of the solvent tetrahydrofuran, stir thoroughly, then add sodium hydroxide solution until the pH = 10.0, then raise the temperature to 60 °C, keep stirring for 8 h. After the reaction is completed, add dilute hydrochloric acid until the reaction solution is neutral, extract and collect the organic phase, and remove the solvent under reduced pressure to obtain a benzotriazole derivative; S3. Weigh 1 g of mercapto-modified aluminum nitride, add it to 20 g of the solvent tetrahydrofuran, disperse it evenly by ultrasonic treatment. In an inert gas atmosphere, add 0.54 g of the benzotriazole derivative, and at the same time add a photoinitiator (Irgacure 2959) accounting for 3% of the mass of the benzotriazole derivative. Place it in a room temperature environment, irradiate it under UV light with a wavelength of 365 nm and an intensity of 30 mW / cm 2 for 60 min, centrifuge the product, wash it with ethanol 3 times, and dry under vacuum to obtain a heat-conducting filler.

[0073] (2) Weigh 100 parts of POE resin ENGAGE 7387 and 6 parts of the heat-conducting filler, mix them evenly in a blender, and then co-extrude and cast at 105 °C to obtain a modified POE film; (3) First, corona-treat the Japanese Toray Lumirror UY34 PET film, with a corona value of 50 dyne, then laminate and hot-press the modified POE film and the PET film. The hot-pressing temperature is 165 °C, the pressure is 4 MPa, and the pressure holding time is 8 s to obtain a heat-conducting PET / POE composite film, that is, the carrier film.

[0074] Example 5: A method for preparing a carrier film in a metallized electrode of a solar cell, comprising the following steps: (1) Prepare a heat-conducting filler: 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 them thoroughly, stir at 50 °C for 5 h, then perform vacuum filtration, wash with pure water 3 times, and dry under vacuum to obtain mercapto-modified aluminum nitride; S2. Weigh 1.25 g of allyl glycidyl ether and 1.34 g of 5-aminobenzotriazole, add them to 10 g of the solvent tetrahydrofuran. After stirring well, add sodium hydroxide solution until the pH reaches 9.0. Then raise the temperature to 50 °C and stir for 6 h while maintaining the temperature. After the reaction ends, add dilute hydrochloric acid until the reaction solution becomes neutral. Extract and collect the organic phase, and remove the solvent under reduced pressure to obtain the benzotriazole derivative; S3. Weigh 1 g of mercapto-modified aluminum nitride and add it to 10 g of the solvent tetrahydrofuran. Ultrasonically disperse it evenly. In an inert gas atmosphere, add 0.43 g of the benzotriazole derivative, and at the same time add a photoinitiator (Irgacure 2959) which is 1% of the mass of the benzotriazole derivative. Place it in a room temperature environment and irradiate it under UV light with a wavelength of 365 nm and an intensity of 10 mW / cm 2 for 90 min. Centrifuge to separate the product, wash it 3 times with ethanol, and dry it under vacuum to obtain the thermal conductive filler.

[0075] (2) Weigh 100 parts of POE resin ENGAGE 7387 and 3 parts of the thermal conductive filler, mix them evenly in a blender, and then co-extrude and cast them at 100 °C to obtain the modified POE film; (3) First, corona-treat the Japanese Toray Lumirror UY34 PET film, with the corona value being 48 dyne. Then laminate and hot-press the modified POE film and the PET film together. The hot-pressing temperature is 150 °C, the pressure is 3 MPa, and the pressure-holding time is 4 s to obtain the thermally conductive PET / POE composite film.

[0076] Example 6: A method for preparing a carrier film in a metallized electrode of a solar cell, comprising the following steps: (1) Prepare the thermal conductive filler: 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 them well. After mixing evenly, stir at 60 °C for 10 h, then perform vacuum filtration, wash 3 times with pure water, and dry under vacuum to obtain mercapto-modified aluminum nitride; S2. Weigh 1.48 g of allyl glycidyl ether and 1.34 g of 5-aminobenzotriazole, add them to 30 g of the solvent tetrahydrofuran. After stirring well, add sodium hydroxide solution until the pH reaches 10.0. Then raise the temperature to 70 °C and stir for 12 h while maintaining the temperature. After the reaction ends, add dilute hydrochloric acid until the reaction solution becomes neutral. Extract and collect the organic phase, and remove the solvent under reduced pressure to obtain the benzotriazole derivative; S3. Weigh 1 g of mercapto-modified aluminum nitride and add it to 30 g of the solvent tetrahydrofuran. Ultrasonically disperse it evenly. In an inert gas atmosphere, add 0.65 g of benzotriazole derivative, and at the same time add a photoinitiator (Irgacure 2959) which is 5% of the mass of the benzotriazole derivative. Place it in a room temperature environment and irradiate it under UV light at 365 nm and 50 mW / cm 2 for 30 min. Centrifuge to separate the product, wash it 3 times with ethanol, and dry it in vacuum to obtain the thermal conductive filler.

[0077] (2) Weigh 100 parts of POE resin ENGAGE 7387 and 8 parts of the thermal conductive filler, mix them evenly in a blender, and then co-extrude and cast them at 110 °C to obtain the modified POE film. (3) First, corona-treat the Japanese Toray Lumirror UY34 PET film with a corona value of 50 dyne, and then laminate and hot-press the modified POE film and the PET film. The hot-pressing temperature is 175 °C, the pressure is 5 MPa, and the pressure holding time is 10 s to obtain the thermally conductive PET / POE composite film.

[0078] Comparative Example 1 A method for preparing a metallized electrode of a solar cell, comprising the following steps: (1) Screen-print a silver-coated copper conductive paste on the back of the HJT cell using a screen (screen parameters: 500 mesh, 9 μm wire diameter, 13 μm screen thickness, 3 μm PI film thickness, 50 35-μm sub-grid lines and 16 main grid lines). Under the condition of a belt speed of 12000 mm / min, dry it at a temperature peak of 180 °C for 150 s.

[0079] (2) Screen-print a silver-coated copper conductive paste on the front of the HJT cell printed with the back grid lines using a screen (screen parameters: 500 mesh, 9 μm wire diameter, 13 μm screen thickness, 3 μm PI film thickness, 80 35-μm sub-grid lines and 16 main grid lines). Under the condition of a belt speed of 12000 mm / min, dry it at a temperature peak of 180 °C for 150 s.

[0080] (3) Place the HJT cell prepared in step (2) in a curing furnace and cure it in an air atmosphere under the condition of a belt speed of 12000 mm / min. Among them, the temperature peak is 200 °C and the sintering time is 6 min to complete the metallization of the HJT solar cell.

[0081] Comparative Example 2 A method for preparing a carrier film in a metallized electrode of a solar cell, which is different from Example 4 in that the thermal conductive filler is replaced with aluminum nitride nanoparticles, and comprises the following steps: 1. Weigh 100 parts of POE resin ENGAGE 7387 and 6 parts of heat-conducting filler (aluminum nitride nanoparticles), mix them evenly in a blender, and then co-extrude and cast them at 105 °C to obtain the modified POE film. 2. First, corona-treat the Japanese Toray Lumirror UY34 PET film with a corona value of 50 dyne. Then, laminate and thermally press the modified POE film and the PET film together. The thermal pressing temperature is 165 °C, the pressure is 4 MPa, and the pressure holding time is 8 s to obtain the heat-conducting PET / POE composite film, which is the carrier film.

[0082] Comparative Example 3 A method for preparing a carrier film in a metallized electrode of a solar cell, which is different from Example 4 in that the preparation process of the heat-conducting filler is different, and includes the following steps: 1. Prepare the heat-conducting filler: 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 them well, stir at 55 °C for 8 h, then perform vacuum filtration, wash 3 times with pure water, and dry in vacuum to obtain mercapto-modified aluminum nitride. S2. Weigh 1 g of mercapto-modified aluminum nitride, add it to 20 g of the solvent tetrahydrofuran, disperse it evenly by ultrasonic treatment, add 1.34 g of 5-aminobenzotriazole, stir well, then dropwise add sodium hydroxide solution until pH = 10.0, then raise the temperature to 60 °C, keep stirring for 8 h. After the reaction ends, dropwise add dilute hydrochloric acid until the reaction solution is neutral, extract and collect the organic phase, and remove the solvent under reduced pressure to obtain the heat-conducting filler. 2. Weigh 100 parts of POE resin ENGAGE 7387 and 6 parts of heat-conducting filler (aluminum nitride nanoparticles), mix them evenly in a blender, and then co-extrude and cast them at 105 °C to obtain the modified POE film. 3. First, corona-treat the Japanese Toray Lumirror UY34 PET film with a corona value of 50 dyne. Then, laminate and thermally press the modified POE film and the PET film together. The thermal pressing temperature is 165 °C, the pressure is 4 MPa, and the pressure holding time is 8 s to obtain the heat-conducting PET / POE composite film, which is the carrier film.

[0083] Experimental Example 1 Apply the metal electrode prepared in Example 1 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: Table 1 Comparison of solar cell test parameters 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* Note: 0* indicates that this is the reference basis, that is, the results of Example 1 are the changed values based on Comparative Example 1.

[0084] As can be seen from Table 1 and Figures 7 - 10 it can be seen that for the solar cell wafers metallized with the metal electrode of the present invention, the surface of the cell is smoother, and there is a gain in the short-circuit current, indicating that the electroformed metal electrode has less light-blocking area and less high-frequency signal loss, thus bringing about an efficiency improvement. More importantly, the metal electrode material of the present invention includes nickel, copper, and tin, all of which are base metal materials and do not involve precious metal silver, resulting in a significant reduction in material cost.

[0085] Experimental Example 2 The properties of the carrier films prepared in Example 4 and Comparative Examples 2-3 were compared, and the results are shown in Table 2 below: Table 2 Comparison of the properties of the battery carrier films Group Tensile Strength (MPa) Peel Strength (N / 15mm) Thermal Conductivity (W / (m·K)) Light Transmittance (%) Yellowing Index (ΔYi) after UV Treatment Light Transmittance Retention Rate (%) after UV Treatment Longitudinal Shrinkage Rate (%) 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 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 tube, irradiation intensity 0.76 W / m 2 , cycle 240 hours, yellowing index refers to GB / T 2409-2008, and UV light transmittance retention rate refers to GB / T 16422.3-2014.

[0086] It can be seen from Table 2 that the carrier film prepared in Example 4 of the present invention has higher strength and better performance in terms of interfacial adhesion, light stability, and stability. It shows that the carrier film prepared by the present invention enhances the mechanical strength and stability on the basis of ensuring light transmittance and thermal conductivity, and also has excellent aging resistance.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a metallized electrode of a solar cell, characterized in that, It includes the following steps: Step 1, electroforming template preparation: Weld an energized circuit on one side of the polished metal substrate and coat an insulating layer, then deposit an anti-electroplating layer, and then etch part of the anti-electroplating layer according to the electrode pattern to form a conductive circuit; Step 2, electroforming metal electrodes: Prepare an electroplating solution, immerse the electroforming template obtained in the first step as the cathode into the electroplating solution, and at the same time connect the side with the conductive circuit to an external power supply, energize for electroforming, wash and dry to obtain electroformed metal electrodes; Step 3, transfer the metal electrodes to the carrier film: Prepare a carrier film, stretch the carrier film to cover the electrode surface, heat and press to embed the film into the side where the electroformed metal electrodes are deposited, peel off the carrier film and the metal electrodes after cooling, and then perform secondary electroplating on the peeled carrier film together with the metal electrodes to obtain a carrier film inlaid with metal electrodes; Step 4, combine the carrier film with the solar cell: Laminating and encapsulating the carrier film inlaid with metal electrodes with the cell sheet, where the side of the carrier film with the metal electrodes faces the surface of the solar cell, and complete the fixation to obtain the metallized electrodes of the solar cell.

2. The preparation method of a metalized electrode of a solar cell according to claim 1, characterized in that, In the said Step 1, the metal substrate is an alloy formed by one or more of copper, aluminum, titanium, and nickel; the anti-electroplating layer is one or a combination of silicon nitride, aluminum oxide, silicon oxide, polyimide, polytetrafluoroethylene, and epoxy resin; the conductive circuit is the exposed area of the metal substrate formed by removing part of the anti-electroplating layer through laser etching or photoresist etching process; the energized circuit is one of copper wire, aluminum wire, and iron wire.

3. The preparation method of a metalized electrode for a solar cell according to claim 1, wherein, In the said Step 2, the electroplating solution is one or a combination of electroplating nickel, electroplating copper, electroplating tin, electroplating copper-tin alloy, and electroplating tin-nickel alloy plating solutions.

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

5. The preparation method of a metalized electrode for a solar cell according to claim 1, characterized in that, In the said Step 2 and Step 3, the secondary electroplating is to connect the peeled carrier film together with the metal electrodes to the negative pole of the DC power supply and immerse them in the tin electroplating tank to complete the tin electroplating.

6. The preparation method of a metalized electrode of a solar cell according to claim 1, characterized in that, In the said Step 4, the lamination is to align the three-layer structure of carrier film / solar cell / carrier film, send it into the lamination equipment, apply uniform pressure to the carrier film and the cell sheet, and heat at the same time, the heating temperature is 130~160°C, and the pressurizing time is 10~120s.

7. The preparation method of a metalized electrode for a solar cell according to claim 1, characterized in that In the said Step 3, the carrier film is a heat-conducting PET / POE composite film, and the preparation method includes: (1) Weigh POE resin and heat-conducting filler and mix them evenly in a blender. The weight ratio of POE resin to heat-conducting filler is 100:2-10, and then co-extrude and cast at 100~110°C to obtain a modified POE film; (2) First, corona-treat the PET film, and then bond and hot-press the modified POE film and the PET film. The hot-pressing temperature is 150~175°C, the pressure is 3~5MPa, and the pressure-holding time is 4~10s to obtain a heat-conducting PET / POE composite film.

8. The preparation method of a metalized electrode of a solar cell according to claim 7, characterized in that, In the said Step 3, the thickness of the PET film layer is 10~50μm, and the thickness of the modified POE film layer is 5~10μm.

9. The preparation method of a metalized electrode of a solar cell according to claim 7, characterized in that, The preparation method of the said heat-conducting filler includes: S1. Weigh aluminum nitride nanoparticles, γ-mercaptopropyltriethoxysilane, ethanol and deionized water, mix them well, stir them at 50-60° C. for 5-10 hours, then vacuum filter, wash them with pure water for 3 times, and vacuum dry them to obtain thiol-modified aluminum nitride; S2, weighing allyl alcohol glycidyl ether and 5-aminobenzotriazole, adding them to tetrahydrofuran solvent, stirring them thoroughly, adjusting the pH to 9.0-10.0, then heating to 50-70° C., keeping the temperature and stirring for 6-12 hours, after the reaction is completed, adjusting the reaction solution to neutral, extracting and collecting the organic phase, and removing 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 dry it in vacuum 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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