A front side fine grid silver paste for TOPCon-0BB modules

Abstract

The present invention discloses a front fine grid silver paste for TOPCon‑0BB components, comprising 86% to 93% silver powder, 1 to 3.5% glass powder, and 7% to 10% organic carrier. The above components are mixed evenly, and a diluent is added, accounting for 0 to 3% of the whole. The above is calculated by mass percentage. The silver powder is composed of a mixture of one or more silver powders, and the average particle size of the silver powder is D50≤2μm, and the maximum particle size is D100≤4μm. The glass powder is one or more glass powders with lead oxide, silicon oxide, and boron oxide as the main body. The present invention relates to the technical field of preparation of front fine grid silver paste. The front fine grid silver paste for TOPCon‑0BB components has more uniform silver paste dispersion, is suitable for narrow opening screen printing technology, reduces shading area, improves battery conversion efficiency, prints without broken grids and virtual printing, and has normal E, which is in line with the trend of fine-line grid line electrodes of 0BB technology.

Description

Technical Field

[0001] The present invention relates to the technical field of preparing front fine grid silver paste, and in particular to a front fine grid silver paste for a TOPCon-0BB component. Background Art

[0002] The silicon material, silicon wafer, and battery links have basically completed the technological leap, and it is difficult to have a major technological change in the short term. The price of silicon materials is close to the cost line of silicon material companies. According to the latest quotation of TrendForce on October 9, 2024, the current price of polysilicon dense material is about 41,000 yuan / ton, and it is more difficult to reduce costs in the silicon link. There is still room for cost reduction in non-silicon links: the cost reduction in non-silicon links currently mainly refers to the savings in auxiliary materials and consumables in the manufacturing process, such as silver paste, solder ribbon, adhesive film, photovoltaic glass, etc. Photovoltaic silver paste is the core electrode material in the cell structure, with high technical barriers and a large market share. The cost of silver paste accounts for about 13% of the cost of photovoltaic cells, second only to the cost of silicon wafers. The proportion of silver powder in direct material costs is as high as more than 90%. The demand for reducing silver in the N-type era is becoming more urgent.

[0003] In order to reduce the printing cost of silver paste for solar cells, busbar-free 0BB (ZeroBusbar) solar cells came into being. Busbar-free 0BB technology refers to the solar cell that only prints the secondary (fine) grid, eliminates the main grid, and uses a solder strip to directly interconnect the fine grid to derive current. Compared with the traditional multi-busbar SMBB (Super-MultipleBusbar) technology, 0BB can significantly reduce the cost of silver paste in the solar cell link, increase the bifaciality, and improve efficiency by reducing the shading area and shortening the current transmission path, thereby achieving cost reduction and efficiency improvement.

[0004] The following are the technical advantages of 0BB: 1) The application of 0BB on TOPCon can reduce the silver paste consumption by 10-20%.

[0005] 2) It is expected that 0BB can achieve a component power efficiency improvement of more than 5W.

[0006] 3) 0BB is conducive to the thinning of silicon wafers, which can solve the problems of hidden cracks and broken grids caused by welding after thinning, and help achieve a breakthrough in battery cells with a thickness of less than 100 microns.

[0007] 4) 0BB eliminates the main grid line and uses thinner solder strips. At the same time, due to the use of thinner solder strips, the corresponding film weight can be further reduced by about 100g.

[0008] The current TOPCon front sub-grid silver paste cannot provide high welding tension, which affects the subsequent service life of the component. The paste with qualified welding tension on the market cannot be used for printing of narrow line width sub-grid lines. There are many broken grids and virtual printing, and the EL is unqualified. Therefore, it is necessary to develop a special TOPCon-0BB sub-grid silver paste and formulate a suitable adaptation process to solve the problem that the existing N-type TOPCon battery front main grid silver paste cannot take into account both welding tension and improving battery efficiency. Summary of the invention

[0009] To achieve the above objectives, the present invention is implemented through the following technical scheme: a front fine grid silver paste for TOPCon-0BB components, comprising 86%~93% silver powder, 1~3.5% glass powder, and 7%~10% organic carrier. The above ingredients are mixed evenly, and a diluent is added, accounting for 0~3% of the whole, and the above is calculated in terms of mass percentage.

[0010] Preferably, the silver powder is a mixture of one or more types of silver powders, and the average particle size D50 of the silver powder is ≤2 μm, and the maximum particle size D100 is ≤4 μm.

[0011] Preferably, the glass powder is one or more glass powders with lead oxide-silicon oxide-boron oxide as the main body, and the chemical composition of the glass powder, in molar percentage, comprises Pb3O415%~80%, SiO22%~20%, GeO20~20%, ZnO0%~20%, B2O35~60%, BiO21~30%, Al2O30.2~4%, 1~12% of one or more of the alkali metal oxides Li2O, Na2O, K2O, Cs2O, etc., and 1~4% of one or more of the alkaline earth metal oxides BeO, MgO, CaO, SrO, BaO, etc. The particle size of the glass powder is D10≤1μm, D50≤1.5μm, and D98≤3μm.

[0012] Preferably, the organic carrier composition includes a base resin, a solvent, a dispersant, a lubricant and a thixotropic agent, and is prepared by mixing, stirring and heating the components, wherein the heating temperature is 70-90° C., the heating time is 2-10 hours, and the stirring speed is 1000 r / min.

[0013] Preferably, the base resin contains one or more of polyvinyl butyral, phenol resin, ethyl cellulose, rosin resin, acrylic resin and the like.

[0014] Preferably, the organic solvent includes one or more of terpineol, diethylene glycol monooctyl ether, diethyl phthalate, butyl carbitol, butyl carbitol acetate, benzyl alcohol and alcohol ester dodecahydrate.

[0015] Preferably, the dispersant is one or more of tallow modified amine, polyethylene glycol oleate, Nanben ED120, and Nanben ED420.

[0016] Preferably, the lubricant is dimethyl silicone oil, including one or more of silicone oils with different molecular weight viscosities, amino-modified silicone oils, and epoxy-modified silicone oils, and the viscosity of the silicone oil ranges from 10 to 1000 cs.

[0017] Preferably, the thixotropic agent comprises one or more of Nanben ET2020, polyamide wax, and acrylic resin.

[0018] Preferably, the preparation method of the front sub-grid silver paste of the N-type TOPCon0BB battery is a two-step mixing method, comprising: A. Premixing and grinding the organic carrier and the glass powder, and centrifuging to obtain a premix; B. Add silver powder to the premix, mix and grind by three rollers, and centrifuge again to obtain the silver paste for the front sub-grid of the TOPCon-0BB battery; C. Add diluent to 0BB secondary grid silver paste before printing and centrifuge, adjust according to the on-site printing situation, accounting for 0.2~2% of the total; The diluent is diethylene glycol butyl ether acetate, and the added amount accounts for 0-3% of the slurry.

[0019] The present invention provides a front fine grid silver paste for TOPCon-0BB components. It has the following beneficial effects: The front fine grid silver paste used for the TOPCon-0BB component contains specific components B and Al in the silver paste glass component. Since the front of the TOPCon battery is boron diffused, B and Al have the same outer electronic structure and similar properties, which increases the high-temperature adhesion of glass to silicon and is beneficial to the diffusion of elements and silver ions in the glass during the sintering process, thereby increasing the silver-silicon contact, and then increasing the adhesion of the silver paste and enhancing its conductivity. On the premise of improving the battery conversion efficiency, the tension of the 0BB welding strip and the front fine grid welding can be improved. In addition, this technology adopts a two-step mixing method to prepare the TOPCon-0B front sub-grid silver paste, so that the silver paste is dispersed more evenly, which is suitable for narrow-opening screen printing technology, reduces the shading area, improves the battery conversion efficiency, prints without broken grids or virtual printing, and has normal E, which is in line with the trend of fine-line grid line electrodes of 0BB technology. DETAILED DESCRIPTION

[0020] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] Embodiment, the present invention provides a technical solution: a front fine grid silver paste for TOPCon-0BB components, comprising 89% silver powder, 2.5% glass powder, 8.5% organic carrier, the above ingredients are mixed evenly, and a diluent is added, accounting for 1% of the whole, and the above is calculated by mass percentage.

[0022] The chemical composition of the glass powder, in molar percentage, includes 38% Pb3O4, 14% SiO2, 2% GeO2, 7% ZnO, 27% B2O3, 1.5% BiO2, 1.5% Al2O3, 7% Li2O, and 2% BaO.

[0023] The particle diameters of the glass powder are D10, D50, and D98, respectively, of 0.73 μm, 1.26 μm, and 2.82 μm.

[0024] The average particle size D50 of the silver powder is 1.39 μm, and D98 is 3.67 μm.

[0025] The organic carrier includes, by mass percentage, 5% polyvinyl butyral, 6% rosin resin, 10% diethylene glycol monooctyl ether, 20% butyl carbitol, 15% benzyl alcohol, 15% butyl carbitol acetate, 5% ED120, 5% silicone oil 20, 5% silicone oil 100, 5% silicone oil 500, and 9% ET2020. The components are mixed, stirred, heated, and reacted to form the product, wherein the heating temperature is 85°C, the heating time is 3 hours, and the stirring speed is 1000 r / min.

[0026] The front fine grid silver paste of the prepared TOPCon-0BB module was screen printed, and then sintered in a belt sintering furnace and laser assisted sintering (LECO) was performed to obtain 0BB cells, and the 0BB ribbon was welded for tensile testing. The photoelectric conversion efficiency of the cell was tested using a HalmI-V efficiency tester, and the pull-off force between the grid electrode and the 0BB ribbon was tested using a horizontal photovoltaic ribbon peel strength tensile tester. The printing efficiency and contact of the cell were evaluated using EL. The test results are shown in the following table:

[0027] It can be seen that the photoelectric conversion efficiency and tension of the cell using the TOPCon-0BB front fine grid silver paste of the present invention are better than those of the commercial silver paste, and the printing has no broken grid fog and the EL is normal.

[0028] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field and related fields without creative work should fall within the scope of protection of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention are implemented according to the conventional means in the field unless otherwise specified and limited.

Claims

1. A front fine grid silver paste for TOPCon-0BB components, characterized by: It contains 86% to 93% silver powder, 1% to 3.5% glass powder, and 7% to 10% organic carrier. The above ingredients are mixed evenly, and a diluent is added, accounting for 0 to 3% of the whole. The above is calculated by mass percentage.

2. The front fine grid silver paste for TOPCon-0BB module according to claim 1, characterized in that: The silver powder is a mixture of one or more types of silver powders, and the average particle size D50 of the silver powder is ≤2 μm, and the maximum particle size D100 is ≤4 μm.

3. The front fine grid silver paste for TOPCon-0BB module according to claim 2, characterized in that: The glass powder is one or more glass powders with lead oxide-silicon oxide-boron oxide as the main body. The chemical composition of the glass powder, in molar percentage, includes Pb3O415%~80%, SiO22%~20%, GeO20~20%, ZnO0%~20%, B2O35~60%, BiO21~30%, Al2O30.2~4%, 1~12% of one or more of alkali metal oxides such as Li2O, Na2O, K2O, Cs2O, etc., and 1~4% of one or more of alkaline earth metal oxides such as BeO, MgO, CaO, SrO, BaO, etc. The particle size of the glass powder is D10≤1μm, D50≤1.5μm, and D98≤3μm.

4. The front fine grid silver paste for TOPCon-0BB module according to claim 3, characterized in that: The organic carrier comprises a base resin, a solvent, a dispersant, a lubricant and a thixotropic agent, and is prepared by mixing, stirring and heating the components for reaction, wherein the heating temperature is 70-90° C., the heating time is 2-10 hours, and the stirring speed is 1000 r / min.

5. The front fine grid silver paste for TOPCon-0BB module according to claim 4, characterized in that: The base resin contains one or more of polyvinyl butyral, phenol resin, ethyl cellulose, rosin resin, acrylic resin and the like.

6. The front fine grid silver paste for TOPCon-0BB module according to claim 5, characterized in that: The organic solvent includes one or more of terpineol, diethylene glycol monooctyl ether, diethyl phthalate, butyl carbitol, butyl carbitol acetate, benzyl alcohol and alcohol ester dodecahydrate.

7. The front fine grid silver paste for TOPCon-0BB module according to claim 6, characterized in that: The dispersant is one or more of tallow modified amine, polyethylene glycol oleate, Nanben ED120, and Nanben ED420.

8. The front fine grid silver paste for TOPCon-0BB module according to claim 7, characterized in that: The lubricant is dimethyl silicone oil, including one or more of silicone oils with different molecular weight viscosities, amino-modified silicone oils, and epoxy-modified silicone oils. The viscosity of the silicone oil ranges from 10 to 1000 cs.

9. The front fine grid silver paste for TOPCon-0BB module according to claim 8, characterized in that: The thixotropic agent includes one or more of Nanben ET2020, polyamide wax, and acrylic resin.

10. The front fine grid silver paste for TOPCon-0BB module according to claim 9, characterized in that: The preparation method of the front sub-grid silver paste of the N-type TOPCon0BB battery is a two-step mixing method, comprising: A. Premixing and grinding the organic carrier and the glass powder, and centrifuging to obtain a premix; B. Add silver powder to the premix, mix and grind by three rollers, and centrifuge again to obtain the silver paste for the front sub-grid of the TOPCon-0BB battery; C. Add diluent to the 0BB secondary grid silver paste before printing and centrifuge, accounting for 0.2~2% of the total; The diluent is diethylene glycol butyl ether acetate, and the added amount accounts for 0-3% of the slurry.

Images