A low-corrosion topcon silver paste, a preparation method and application thereof

Abstract

The application provides a low-corrosion TOPCon silver paste, a preparation method and application thereof, and belongs to the field of solar cells. The TOPCon silver paste is composed of the following components: 40-70 parts of silver powder, 5-25 parts of silver-coated tungsten, 1-5 parts of glass material, 1-5 parts of modified nano calcium carbonate, 10-15 parts of organic carrier, and 0.5-2 parts of organic additive. The modified nano calcium carbonate is uniformly dispersed on the surface of the glass powder through physical adsorption and chemical bonding, can reduce the corrosion of the silver paste to the surface of the silicon wafer, and maintains the integrity of the surface of the silicon wafer. Meanwhile, the modified nano calcium carbonate forms a dense conductive network in the sintering process, reduces the contact resistance, and improves the conversion efficiency of the battery. In addition, the modified nano calcium carbonate improves the interfacial bonding force between the silver paste and the silicon wafer, enhances the adhesion and tensile strength of the silver paste. Therefore, the corrosion resistance, conductivity and mechanical properties of the silver paste for the TOPCon battery are improved.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to a low-corrosion TOPCon silver paste, its preparation method, and its application. Background Technology

[0002] TOPCon cells use N-type silicon as a substrate and achieve passivation contacts through tunneling oxide, thereby improving the performance of solar cells. Its structural feature is the fabrication of an ultrathin tunneling oxide layer (1–2 nm) and a layer of doped polycrystalline silicon on the back of the cell, forming a passivation contact structure. This design significantly reduces recombination in the metal contact region while maintaining excellent contact performance, thus greatly improving the efficiency of the solar cell.

[0003] However, traditional TOPCon silver paste is prone to corroding the silicon wafer surface during sintering, leading to surface damage and affecting battery performance and reliability. Simultaneously, the high contact resistance between the conductive phase (silver powder) in the silver paste and the silicon wafer surface affects the battery's fill factor and conversion efficiency. Furthermore, insufficient adhesion between the silver paste and the silicon wafer surface makes it prone to detachment during battery use, impacting long-term reliability. Therefore, it is crucial to simultaneously improve the corrosivity, conductivity, and mechanical properties of silver paste for TOPCon batteries. Summary of the Invention

[0004] This application provides a low-corrosion TOPCon silver paste, its preparation method, and its application to solve the following technical problem: how to simultaneously improve the corrosivity, conductivity, and mechanical properties of silver paste for TOPCon batteries.

[0005] In a first aspect, this application provides a low-corrosion TOPCon silver paste, which, by weight, is composed of the following components: 40-70 parts silver powder, 5-25 parts silver-coated tungsten, 1-5 parts glass material, 1-5 parts modified nano-calcium carbonate, 10-15 parts organic carrier, and 0.5-2 parts organic additives.

[0006] Optionally, the modified nano-calcium carbonate comprises:

[0007] Nano-calcium carbonate, wherein the particle size of the nano-calcium carbonate is 10nm to 30nm;

[0008] A silica layer is formed on the surface of the nano-calcium carbonate, and the thickness of the silica layer is 1-10 nm.

[0009] A polyacrylic acid layer is formed on the surface of the silica layer, and the thickness of the polyacrylic acid layer is 10-30 nm.

[0010] Optionally, by mass fraction, the organic additive consists of the following chemical components: ammonium polyacrylate: 20-40%, cellulose ether: 10-30%, polyethylene glycol: 10-30%, benzotriazole: 10-30%, and silane coupling agent: 10-30%.

[0011] Optionally, the glass material, by molar percentage, comprises the following components: 50–70 mol.% lead borosilicate glass, 20–40 mol.% aluminosilicate glass, 1–3 mol.% bismuth oxide, 1–3 mol.% zinc oxide, 0.5–2 mol.% nano-silica, and 1–3 mol.% lanthanum oxide.

[0012] Optionally, by mass fraction, the organic carrier is composed of the following chemical components: terpineol: 40-60%, ethyl acetate: 20-30%, polyether-modified siloxane: 1-5%, polyvinyl butyral: 10-20%, epoxy resin: 1-10%, and acrylic resin: 1-10%.

[0013] Secondly, this application provides a method for preparing the low-corrosion TOPCon silver paste according to any embodiment of the first aspect, the method comprising:

[0014] The organic carrier is mixed with the organic additives to obtain a mixture;

[0015] Silver powder, silver-coated tungsten, glass material, and modified nano-calcium carbonate are added to the mixture to obtain a mixed slurry;

[0016] The mixed slurry is homogenized to obtain the TOPCon silver paste.

[0017] Optionally, the homogenization process includes the following parameters: homogenization pressure of 20-30 MPa, homogenization temperature of 40-60°C, and homogenization cycles of 2-5.

[0018] Optionally, the preparation method of the modified nano-calcium carbonate includes:

[0019] The nano-calcium carbonate is subjected to low-temperature plasma treatment to form highly active groups on the surface of the nano-calcium carbonate, thereby obtaining the first active calcium carbonate.

[0020] A silica layer is deposited on the surface of the first active calcium carbonate using atomic layer deposition technology to obtain the second active calcium carbonate;

[0021] The second activated calcium carbonate was dispersed in an acrylic acid solution, and then ammonium persulfate was added to carry out an in-situ polymerization reaction to obtain the modified nano calcium carbonate.

[0022] Optionally, the mass ratio of the second activated calcium carbonate, the acrylic acid solution, and the ammonium persulfate is 100:(50-150):(0.5-2).

[0023] Thirdly, this application provides an application of the TOPCon silver paste described in any embodiment of the first aspect, characterized in that the silver paste is used in TOPCon solar cells.

[0024] The technical solutions provided in this application have the following advantages compared with the prior art:

[0025] This application provides a low-corrosion TOPCon silver paste. Modified nano-calcium carbonate is uniformly dispersed on the surface of glass powder through physical adsorption and chemical bonding, which can reduce the corrosion of the silicon wafer surface by the silver paste and maintain the integrity of the silicon wafer surface. Simultaneously, the modified nano-calcium carbonate forms a dense conductive network during sintering, reducing contact resistance and improving the battery's conversion efficiency. Furthermore, the modified nano-calcium carbonate improves the interfacial bonding force between the silver paste and the silicon wafer, enhancing the adhesion and tensile strength of the silver paste. Thus, it simultaneously improves the corrosion resistance, conductivity, and mechanical properties of the silver paste for TOPCon batteries. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic flowchart illustrating a method for preparing a low-corrosion TOPCon silver paste, as provided in an embodiment of this application. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0031] In a first aspect, this application provides a low-corrosion TOPCon silver paste, which, by weight, is composed of the following components: 40-70 parts silver powder, 5-25 parts silver-coated tungsten, 1-5 parts glass material, 1-5 parts modified nano-calcium carbonate, 10-15 parts organic carrier, and 0.5-2 parts organic additives.

[0032] The functions of each component in TOPCon silver paste are as follows:

[0033] Silver powder (40-70 parts): As a conductive material, silver powder's main function is to provide conductivity to the solar cells. The content and particle size distribution of silver powder have a significant impact on the conductivity and printability of the silver paste. A high content of silver powder can improve conductivity, but too much silver powder may lead to a decrease in printability.

[0034] Silver-coated tungsten (5-25 parts): Silver-coated tungsten is a composite particle with a tungsten core and a silver outer shell. Tungsten has a high melting point and high hardness, which can improve the high-temperature resistance and mechanical strength of silver paste. At the same time, the silver outer shell maintains good electrical conductivity. The addition of silver-coated tungsten can balance the conductivity, high-temperature resistance, and mechanical strength of silver paste. In addition, tungsten, as a base metal, is much cheaper than silver. Therefore, using silver-coated tungsten to replace part of the silver powder in conductive photovoltaic paste can significantly reduce material costs.

[0035] Glass material (1-5 parts): During sintering, the glass material forms a dense glass phase, acting as a binder and passivator. It firmly bonds conductive materials such as silver powder to the solar cells while preventing corrosion of the cell surface. The composition and content of the glass material have a significant impact on the sintering performance and corrosion resistance of the silver paste.

[0036] Modified nano-calcium carbonate (1-5 parts): Modified nano-calcium carbonate is uniformly dispersed on the surface of glass powder through physical adsorption and chemical bonding, which can reduce the corrosion of the silicon wafer surface by silver paste and maintain the integrity of the silicon wafer surface. Simultaneously, modified nano-calcium carbonate forms a dense conductive network during sintering, reducing contact resistance and improving the battery conversion efficiency. Furthermore, modified nano-calcium carbonate improves the interfacial bonding force between the silver paste and the silicon wafer, enhancing the adhesion and tensile strength of the silver paste.

[0037] Organic carrier (10-15 parts): The organic carrier is the solvent and dispersion medium for the silver paste, providing it with good flowability and printability. The composition and content of the organic carrier directly affect the viscosity, drying speed, and printability of the silver paste.

[0038] Organic additives (0.5-2 parts): Organic additives are mainly used to adjust the rheological properties, dispersibility and stability of silver paste.

[0039] In some embodiments, the organic additive is composed of the following chemical components by mass fraction: ammonium polyacrylate: 20-40%, cellulose ether: 10-30%, polyethylene glycol: 10-30%, benzotriazole: 10-30%, and silane coupling agent: 10-30%.

[0040] Ammonium polyacrylate and cellulose ether are used as dispersants to prevent particle agglomeration; polyethylene glycol is used as a plasticizer to improve the flexibility of the silver paste; benzotriazole is used as a corrosion inhibitor to reduce the corrosion of the substrate by the silver paste; and silane coupling agent enhances the adhesion between the silver paste and the substrate.

[0041] In some embodiments, the glass material, by molar percentage, comprises the following components: 50-70 mol.% lead borosilicate glass, 20-40 mol.% aluminosilicate glass, 1-3 mol.% bismuth oxide, 1-3 mol.% zinc oxide, 0.5-2 mol.% nano-silica, and 1-3 mol.% lanthanum oxide.

[0042] It should be noted that lead borosilicate glass (PbO-B2O3-SiO2 system) is a typical low-melting-point glass with good wettability, fluidity, and a low softening temperature, making it suitable for low-temperature sintering processes. By mass fraction, lead borosilicate glass consists of the following chemical composition: PbO: 60%, B2O3: 15%, SiO2: 20%, Al2O3: 3%, Na2O: 2%.

[0043] Aluminosilicate glass (Al2O3-SiO2 system) is a high-melting-point glass with excellent high-temperature stability and mechanical strength, making it suitable for high-temperature sintering processes. By mass fraction, aluminosilicate glass consists of the following chemical composition: Al2O3: 30%, SiO2: 60%, CaO: 5%, B2O3: 3%, ZrO2: 2%.

[0044] Glass materials soften during sintering, and the various components play the following roles:

[0045] Lead borosilicate glass (low melting point): softens at low temperatures, promoting interfacial contact between silver powder and the substrate and reducing contact resistance.

[0046] Aluminosilicate glass (high melting point): It remains stable at high temperatures, preventing excessive flow or deformation during the sintering process.

[0047] Bismuth oxide and zinc oxide: Adjust the coefficient of thermal expansion of the glass powder to match the silver powder and the substrate, thereby reducing thermal stress.

[0048] Nano-silica: Improves the dispersibility and interfacial contact effect of glass powder.

[0049] Lanthanum oxide: Lanthanum oxide can improve the chemical stability of glass and reduce corrosion.

[0050] In some embodiments, the modified nano-calcium carbonate comprises:

[0051] Nano-calcium carbonate, wherein the particle size of the nano-calcium carbonate is 10nm to 30nm;

[0052] A silica layer is formed on the surface of the nano-calcium carbonate, and the thickness of the silica layer is 1-10 nm.

[0053] A polyacrylic acid layer is formed on the surface of the silica layer, and the thickness of the polyacrylic acid layer is 10-30 nm.

[0054] Nano-calcium carbonate has a particle size range of 10nm to 30nm. It has extremely high specific surface area and surface activity, which provides the basis for its excellent performance.

[0055] A silica coating layer, ranging from 1 to 10 nm in thickness, tightly coats the surface of the nano-calcium carbonate. The presence of this silica layer not only enhances the stability of the nano-calcium carbonate but also provides additional protection, preventing unnecessary reactions with the external environment. A polyacrylic acid coating layer, ranging from 10 to 30 nm in thickness, lies outside the silica layer. This polyacrylic acid layer exhibits good wettability and dispersibility, contributing to the uniform dispersion of the modified nano-calcium carbonate in various media.

[0056] The unique three-layer structure of modified nano-calcium carbonate—a nano-calcium carbonate core, a silica coating layer, and a polyacrylic acid outer layer—endows it with a series of properties that are beneficial for silver paste applications.

[0057] 1. Reduce the corrosion of silicon wafer surface by silver paste.

[0058] (1) Nano-calcium carbonate core and dispersibility: The particle size of nano-calcium carbonate is between 10 nm and 30 nm. This small size gives it a high specific surface area, making it easy to interact with the surrounding environment. In silver paste, modified nano-calcium carbonate can serve as an effective dispersant. Utilizing its high specific surface area and special surface chemical properties, it can be uniformly dispersed on the surface of glass powder to form a protective layer.

[0059] (2) Chemical stability of the silica layer: The silica layer tightly coats the surface of the nano-calcium carbonate and is chemically stable, making it resistant to reactions with other substances. This silica layer isolates the nano-calcium carbonate from direct contact with the silicon wafer surface, reducing potential chemical reactions and thus lowering the risk of corrosion.

[0060] (3) Physical adsorption and chemical bonding of the polyacrylic acid layer: The polyacrylic acid layer contains abundant functional groups (such as carboxyl groups), which can form physical adsorption interactions such as hydrogen bonds with hydroxyl groups on the silicon wafer surface. Simultaneously, the functional groups in the polyacrylic acid layer may also undergo chemical bonding interactions with silicon atoms on the silicon wafer surface, such as esterification reactions, further enhancing the adhesion to the silicon wafer surface. This dual effect of physical adsorption and chemical bonding allows the modified nano-calcium carbonate to firmly adhere to the silicon wafer surface, forming an effective protective barrier.

[0061] 2. Forming a dense conductive network reduces contact resistance.

[0062] (1) Nano-calcium carbonate and conductivity: Although nano-calcium carbonate itself has limited conductivity, it can increase the number of conductive channels in silver paste when used as a filler. When modified nano-calcium carbonate is uniformly dispersed on the surface of glass powder, its small particle size and high specific surface area help to form more conductive channels.

[0063] (2) Conductivity aid of the silica layer: Although the silica layer is not conductive, its tight coating structure helps maintain the uniformity of the dispersion of nano-calcium carbonate in the silver paste and prevents agglomeration. This uniform dispersion helps to form a denser conductive network during sintering.

[0064] (3) Carbonization and conductivity enhancement of the polyacrylic acid layer: During the sintering process, the polyacrylic acid layer may partially decompose or carbonize, forming a carbonaceous layer with certain conductivity. This carbonaceous layer can further increase the number of conductive channels in the silver paste and improve conductivity. At the same time, the carbonaceous layer forms a good interfacial bond with nano-calcium carbonate and glass powder, which helps to reduce contact resistance.

[0065] III. Improving the interfacial adhesion between silver paste and silicon wafers

[0066] (1) Wetting and adhesion of the polyacrylic acid layer: The polyacrylic acid layer has good wettability and adhesion, and can form a good interfacial bond with the silicon wafer surface. This wettability and adhesion helps the modified nano-calcium carbonate to be evenly distributed and firmly adhered to the silicon wafer surface.

[0067] (2) Synergistic effect of chemical bonding and physical adsorption: As mentioned above, the functional groups in the polyacrylic acid layer can chemically bond with the silicon wafer surface, while the polyacrylic acid segments themselves can also tightly bind to the silicon wafer surface through physical adsorption. This synergistic effect of chemical bonding and physical adsorption enables the modified nano-calcium carbonate to significantly improve the interfacial bonding force between the silver paste and the silicon wafer.

[0068] (3) Improved interfacial adhesion and enhanced silver paste performance: Enhanced interfacial adhesion helps improve the adhesion and tensile strength of the silver paste. This means that during the use of the solar cells, the silver paste can adhere more firmly to the silicon wafer surface, making it less likely to fall off or crack. This ensures the stability and reliability of the solar cells, and improves the conversion efficiency and lifespan of the cells.

[0069] In summary, the unique three-layer structure of modified nano-calcium carbonate enables it to be uniformly dispersed on the surface of glass powder through physical adsorption and chemical bonding, reducing the corrosion of silicon wafers by silver paste. Simultaneously, it forms a dense conductive network during sintering, reducing contact resistance. Furthermore, it improves the interfacial bonding between the silver paste and the silicon wafer, enhancing the adhesion and tensile strength of the silver paste. These properties give modified nano-calcium carbonate significant advantages in silver paste applications.

[0070] In some embodiments, the organic carrier is composed of the following chemical components by mass fraction: terpineol: 40-60%, ethyl acetate: 20-30%, polyether-modified siloxane: 1-5%, polyvinyl butyral: 10-20%, epoxy resin: 1-10%, and acrylic resin: 1-10%.

[0071] The organic carrier provides the rheological, wettable, and drying properties of the slurry, and its composition is designed as follows:

[0072] Terpineol (high-boiling-point solvent): provides good rheological properties, suitable for printing processes.

[0073] Ethanol (low-boiling-point solvent): accelerates the drying speed of the paste and reduces printing defects.

[0074] Polyether-modified siloxane (wetting agent): reduces the surface tension of the slurry and enhances its wettability to the substrate.

[0075] Polyvinyl butyral (thermally decomposable polymer): It decomposes into gas during sintering, forming a microporous structure and promoting the complete volatilization of the organic carrier.

[0076] Figure 1 This is a schematic flowchart illustrating a method for preparing a low-corrosion TOPCon silver paste, as provided in an embodiment of this application.

[0077] Secondly, such as Figure 1 As shown, this application provides a method for preparing low-corrosion TOPCon silver paste according to any embodiment of the first aspect, the method comprising:

[0078] S1. Mix the organic carrier with the organic additives to obtain a mixture;

[0079] S2. Add silver powder, silver-coated tungsten, glass material and modified nano-calcium carbonate to the mixture to obtain a mixed slurry;

[0080] S3. The mixed slurry is homogenized to obtain the TOPCon silver paste.

[0081] In some embodiments, the homogenization process includes the following parameters: homogenization pressure of 20-30 MPa, homogenization temperature of 40-60°C, and homogenization cycles of 2-5.

[0082] Homogenization can further refine the particles and improve the uniformity and stability of the silver paste. The choice of homogenization pressure and temperature directly affects the rheological properties and dispersibility of the silver paste.

[0083] In some embodiments, the method for preparing the modified nano-calcium carbonate includes:

[0084] The nano-calcium carbonate is subjected to low-temperature plasma treatment to form highly active groups on the surface of the nano-calcium carbonate, thereby obtaining the first active calcium carbonate.

[0085] A silica layer is deposited on the surface of the first active calcium carbonate using atomic layer deposition technology to obtain the second active calcium carbonate;

[0086] The second activated calcium carbonate was dispersed in an acrylic acid solution, and then ammonium persulfate was added to carry out an in-situ polymerization reaction to obtain the modified nano calcium carbonate.

[0087] In some embodiments, the low-temperature plasma treatment includes the following parameters: power of 50-100W, treatment time of 10-20min, and oxygen flow rate of 30-80mL / min.

[0088] It should be noted that low-temperature plasma treatment: Low-temperature plasma treatment can form highly active groups on the surface of nano-calcium carbonate, improve the reactivity of nano-calcium carbonate, and provide active sites for subsequent silica layer deposition.

[0089] Atomic layer deposition (ALD) technology: ACD technology can uniformly deposit a silicon dioxide layer on the surface of nano-calcium carbonate, thereby improving the chemical stability and mechanical strength of nano-calcium carbonate.

[0090] In-situ polymerization reaction: In-situ polymerization reaction can form a polyacrylic acid layer on the surface of silica layer, which further improves the compatibility between nano-calcium carbonate and organic carrier, reduces particle agglomeration, and improves the dispersibility and stability of silver paste.

[0091] In some embodiments, the mass ratio of the second activated calcium carbonate, the acrylic acid solution, and the ammonium persulfate is 100:(50-150):(0.5-2).

[0092] Thirdly, this application provides an application of the TOPCon silver paste described in any embodiment of the first aspect, characterized in that the silver paste is used in TOPCon solar cells.

[0093] In summary, the low-corrosion TOPCon silver paste, its preparation method, and its application provided in this application have the following advantages:

[0094] (1) Improved overall performance of TOPCon battery silver paste: Through careful design of components and ratios, the TOPCon silver paste provided in this application has improved corrosion resistance, conductivity and mechanical properties. This is due to the synergistic effect between the components, such as silver powder providing high conductivity, silver-coated tungsten enhancing high temperature resistance and mechanical strength, and modified nano-calcium carbonate reducing corrosion and enhancing interfacial bonding.

[0095] (2) Reduced material costs: The introduction of silver-coated tungsten significantly reduces the cost of silver paste. Tungsten, as a base metal, is much cheaper than silver, but silver-coated tungsten particles can still maintain good conductivity, thus reducing the amount of silver used while ensuring performance.

[0096] (3) Unique modified nano-calcium carbonate structure: The three-layer structure of modified nano-calcium carbonate (nano-calcium carbonate core, silica coating layer, and polyacrylic acid outer layer) gives it excellent dispersibility, stability, and interfacial bonding. This structure not only reduces the corrosion of the silicon wafer surface by silver paste, but also improves the conversion efficiency and lifespan of the battery.

[0097] (4) Optimized glass material composition: The glass material is composed of multiple components such as lead borosilicate glass and aluminosilicate glass. These components play important roles in the sintering process, such as promoting interfacial contact and preventing excessive flow or deformation. This optimized composition enables the silver paste to form a dense glass phase after sintering, further improving the corrosion resistance and stability of the battery.

[0098] (5) Flexible preparation methods and parameter adjustments: This application provides detailed preparation methods, including steps such as mixing and homogenization, as well as methods for preparing modified nano-calcium carbonate. These methods and parameters can be adjusted according to actual needs to meet the requirements of different application scenarios.

[0099] (6) Broad application prospects: The TOPCon silver paste of this application is particularly suitable for TOPCon solar cells, but may also be applicable to other types of solar cells or electronic packaging fields. Its excellent performance enables the cells to maintain high conversion efficiency and stability during long-term use.

[0100] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0101] Example 1

[0102] This embodiment provides a low-corrosion TOPCon silver paste, which, by weight, is composed of the following components: 60 parts silver powder, 20 parts silver-coated tungsten (AgW50), 3 parts glass material, 2 parts modified nano-calcium carbonate, 13 parts organic carrier, and 2 parts organic additives.

[0103] The modified nano-calcium carbonate includes:

[0104] Nano-calcium carbonate, wherein the particle size of the nano-calcium carbonate is in the range of 10 nm to 30 nm;

[0105] A silica layer is formed on the surface of the nano-calcium carbonate, and the thickness of the silica layer is in the range of 1 to 10 nm.

[0106] A polyacrylic acid layer is provided, which is coated on the surface of the silica layer, and the thickness of the polyacrylic acid layer is in the range of 10 to 30 nm.

[0107] The organic additives, by mass fraction, consist of the following chemical components: ammonium polyacrylate: 30%, cellulose ether: 20%, polyethylene glycol: 20%, benzotriazole: 20%, and silane coupling agent: 10%.

[0108] The glass material, by molar percentage, comprises the following components: 60 mol.% lead borosilicate glass, 33 mol.% aluminosilicate glass, 2 mol.% bismuth oxide, 2 mol.% zinc oxide, 1 mol.% nano-silica, and 2 mol.% lanthanum oxide.

[0109] The organic carrier, by mass fraction, is composed of the following chemical components: terpineol: 50%, ethanol: 25%, polyether-modified siloxane: 2%, polyvinyl butyral: 13%, epoxy resin: 5%, and acrylic resin: 5%.

[0110] Based on the above-mentioned TOPCon silver paste, this embodiment also provides a method for preparing the low-corrosion TOPCon silver paste, the method comprising:

[0111] S11. Mix the organic carrier with the organic additive to obtain a mixture;

[0112] S21. Add silver powder, silver-coated tungsten, glass material and modified nano-calcium carbonate to the mixture to obtain a mixed slurry;

[0113] S31. The mixed slurry is homogenized to obtain the TOPCon silver paste. The homogenization process includes the following parameters: homogenization pressure of 25 MPa, homogenization temperature of 50°C, and homogenization times of 3.

[0114] The method for preparing the modified nano-calcium carbonate includes:

[0115] Nano-calcium carbonate is subjected to low-temperature plasma treatment to form highly active groups on the surface of the nano-calcium carbonate, thereby obtaining first active calcium carbonate. The low-temperature plasma treatment includes the following parameters: power of 80W, treatment time of 15min, and oxygen flow rate of 60mL / min.

[0116] A silica layer is deposited on the surface of the first active calcium carbonate using atomic layer deposition technology to obtain the second active calcium carbonate;

[0117] The second activated calcium carbonate was dispersed in an acrylic acid solution, and then ammonium persulfate was added to carry out an in-situ polymerization reaction to obtain the modified nano calcium carbonate. The mass ratio of the second activated calcium carbonate, the acrylic acid solution and the ammonium persulfate was 100:100:1. The in-situ polymerization reaction was carried out at a temperature of 70°C for 3 hours.

[0118] Example 2

[0119] This embodiment provides a low-corrosion TOPCon silver paste, which is composed of the following components by weight: 52 parts silver powder, 25 parts silver-coated tungsten (AgW50), 1 part glass material, 5 parts modified nano calcium carbonate, 15 parts organic carrier, and 2 parts organic additives.

[0120] The modified nano-calcium carbonate includes:

[0121] Nano-calcium carbonate, wherein the particle size of the nano-calcium carbonate is in the range of 10 nm to 30 nm;

[0122] A silica layer is formed on the surface of the nano-calcium carbonate, and the thickness of the silica layer is in the range of 1 to 10 nm.

[0123] A polyacrylic acid layer is provided, which is coated on the surface of the silica layer, and the thickness of the polyacrylic acid layer is in the range of 10 to 30 nm.

[0124] The organic additives, by mass fraction, consist of the following chemical components: ammonium polyacrylate: 20%, cellulose ether: 30%, polyethylene glycol: 10%, benzotriazole: 30%, and silane coupling agent: 10%.

[0125] The glass material, by molar percentage, comprises the following components: 52 mol.% lead borosilicate glass, 40 mol.% aluminosilicate glass, 1 mol.% bismuth oxide, 3 mol.% zinc oxide, 1 mol.% nano-silica, and 3 mol.% lanthanum oxide.

[0126] The organic carrier, by mass fraction, is composed of the following chemical components: terpineol: 40%, ethanol: 30%, polyether-modified siloxane: 5%, polyvinyl butyral: 15%, epoxy resin: 1%, and acrylic resin: 9%.

[0127] Based on the above-mentioned TOPCon silver paste, this embodiment also provides a method for preparing the low-corrosion TOPCon silver paste, the method comprising:

[0128] S11. Mix the organic carrier with the organic additive to obtain a mixture;

[0129] S21. Add silver powder, silver-coated tungsten, glass material and modified nano-calcium carbonate to the mixture to obtain a mixed slurry;

[0130] S31. The mixed slurry is homogenized to obtain the TOPCon silver paste. The homogenization process includes the following parameters: homogenization pressure of 20 MPa, homogenization temperature of 40°C, and homogenization times of 5.

[0131] The method for preparing the modified nano-calcium carbonate includes:

[0132] Nano-calcium carbonate is subjected to low-temperature plasma treatment to form highly active groups on the surface of the nano-calcium carbonate, thereby obtaining first active calcium carbonate. The low-temperature plasma treatment includes the following parameters: power of 50W, treatment time of 20min, and oxygen flow rate of 30mL / min.

[0133] A silica layer is deposited on the surface of the first active calcium carbonate using atomic layer deposition technology to obtain the second active calcium carbonate;

[0134] The second activated calcium carbonate was dispersed in an acrylic acid solution, and then ammonium persulfate was added to carry out an in-situ polymerization reaction to obtain the modified nano-calcium carbonate. The mass ratio of the second activated calcium carbonate, the acrylic acid solution and the ammonium persulfate was 100:50:0.5. The in-situ polymerization reaction was carried out at a temperature of 60°C for 4 hours.

[0135] Example 3

[0136] This embodiment provides a low-corrosion TOPCon silver paste, which is composed of the following components by weight: 70 parts silver powder, 7 parts silver-coated tungsten (AgW50), 5 parts glass material, 1 part modified nano calcium carbonate, 15 parts organic carrier, and 2 parts organic additives.

[0137] The modified nano-calcium carbonate includes:

[0138] Nano-calcium carbonate, wherein the particle size of the nano-calcium carbonate is in the range of 10 nm to 30 nm;

[0139] A silica layer is formed on the surface of the nano-calcium carbonate, and the thickness of the silica layer is in the range of 1 to 10 nm.

[0140] A polyacrylic acid layer is provided, which is coated on the surface of the silica layer, and the thickness of the polyacrylic acid layer is in the range of 10 to 30 nm.

[0141] The organic additives, by mass fraction, consist of the following chemical components: ammonium polyacrylate: 40%, cellulose ether: 10%, polyethylene glycol: 20%, benzotriazole: 10%, and silane coupling agent: 20%.

[0142] The glass material, by molar percentage, comprises the following components: 70 mol.% lead borosilicate glass, 21 mol.% aluminosilicate glass, 3 mol.% bismuth oxide, 1 mol.% zinc oxide, 2 mol.% nano-silica, and 3 mol.% lanthanum oxide.

[0143] The organic carrier, by mass fraction, is composed of the following chemical components: terpineol: 50%, ethanol: 20%, polyether-modified siloxane: 1%, polyvinyl butyral: 19%, epoxy resin: 9%, and acrylic resin: 1%.

[0144] Based on the above-mentioned TOPCon silver paste, this embodiment also provides a method for preparing the low-corrosion TOPCon silver paste, the method comprising:

[0145] S11. Mix the organic carrier with the organic additive to obtain a mixture;

[0146] S21. Add silver powder, silver-coated tungsten, glass material and modified nano-calcium carbonate to the mixture to obtain a mixed slurry;

[0147] S31. The mixed slurry is homogenized to obtain the TOPCon silver paste. The homogenization process includes the following parameters: homogenization pressure of 30 MPa, homogenization temperature of 60°C, and homogenization times of 2.

[0148] The method for preparing the modified nano-calcium carbonate includes:

[0149] Nano-calcium carbonate is subjected to low-temperature plasma treatment to form highly active groups on the surface of the nano-calcium carbonate, thereby obtaining first active calcium carbonate. The low-temperature plasma treatment includes the following parameters: power of 100W, treatment time of 10min, and oxygen flow rate of 80mL / min.

[0150] A silica layer is deposited on the surface of the first active calcium carbonate using atomic layer deposition technology to obtain the second active calcium carbonate;

[0151] The second activated calcium carbonate was dispersed in an acrylic acid solution, and then ammonium persulfate was added to carry out an in-situ polymerization reaction to obtain the modified nano-calcium carbonate. The mass ratio of the second activated calcium carbonate, the acrylic acid solution and the ammonium persulfate was 100:150:2. The in-situ polymerization reaction was carried out at a temperature of 80°C for 2 hours.

[0152] Comparative Example 1

[0153] This comparative example is modified from the one disclosed in Example 1 as follows:

[0154] No modified nano-calcium carbonate is added to TOPCon silver paste.

[0155] Comparative Example 2

[0156] This comparative example is modified from the one disclosed in Example 1 as follows:

[0157] Replace the modified nano-calcium carbonate in TOPCon silver paste with nano-calcium carbonate.

[0158] Comparative Example 3

[0159] This comparative example is modified from the one disclosed in Example 1 as follows:

[0160] The modified nano-calcium carbonate in TOPCon silver paste was replaced with the first active calcium carbonate.

[0161] Comparative Example 4

[0162] This comparative example is modified from the one disclosed in Example 1 as follows:

[0163] The modified nano-calcium carbonate in TOPCon silver paste was replaced with a second active calcium carbonate.

[0164] Comparative Example 5

[0165] This comparative example is modified from the one disclosed in Example 1 as follows:

[0166] Homogenization is not performed in the preparation method of TOPCon silver paste.

[0167] The performance of the TOPCon silver pastes obtained in Examples 1-3 and Comparative Examples 1-5 was measured, and the results are shown in Table 1.

[0168] Table 1. Performance of TOPCon silver pastes obtained in Examples 1-3 and Comparative Examples 1-5

[0169] Group Uoc Isc Rs Rsh FF Eta Rc Example 1 0.7332 5.36 0.0122 2869 75.11 25.79 2.68 Example 2 0.7215 5.35 0.0128 2771 74.91 25.14 2.77 Example 3 0.7278 5.35 0.0131 2779 74.89 25.27 2.71 Comparative Example 1 0.6989 5.34 0.0149 2591 65.54 21.24 3.09 Comparative Example 2 0.7011 5.35 0.0139 2667 70.11 23.78 2.87 Comparative Example 3 0.7117 5.35 0.0131 2711 72.23 24.19 2.80 Comparative Example 4 0.7189 5.35 0.0127 2802 74.11 24.48 2.70 Comparative Example 5 0.7201 5.34 0.0125 2803 74.59 24.68 2.69

[0170] It should be noted that Uoc (Open-Circuit Voltage) is the output voltage of a solar cell under no-load (open-circuit) conditions, which is the maximum voltage formed by the accumulation of photogenerated carriers inside the cell.

[0171] Isc (Short-Circuit Current): The output current of a solar cell under short-circuit conditions, which is the maximum current of photogenerated carriers flowing inside the cell.

[0172] Rs (Series Resistance): The series resistance inside a solar cell, including the contact resistance between the silver paste and the silicon wafer, the resistance of the silver paste itself, and the bulk resistance of the silicon wafer.

[0173] Rsh (Shunt Resistance): The parallel resistance inside a solar cell, reflecting the leakage current inside the cell.

[0174] FF (Fill Factor): The ratio of the maximum output power (Pmax) of a solar cell to its theoretical maximum power (Uoc×Isc).

[0175] Eta (Conversion Efficiency): The efficiency with which a solar cell converts light energy into electrical energy.

[0176] Rc (Contact Resistance): The contact resistance between the silver paste and the silicon wafer, reflecting the quality of the interface contact between the silver paste and the silicon wafer.

[0177] As shown in Table 1, the TOPCon silver pastes of Examples 1-3 have the following properties: Uoc: 0.7215V-0.7332V; Isc: 5.35A-5.36A; Rs: 0.0122Ω-0.0131Ω; Rsh: 2771Ω-2869Ω; FF: 74.89%-75.11%; Eta: 25.14%-25.79%; and Rc: 2.68mΩ·cm. 2 ~2.77mΩ·cm 2 .

[0178] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0179] Furthermore, in the description of this application, the terms "comprising" and "including" mean "including but not limited to". In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Here, A and B can be singular or plural.

[0180] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A low-corrosion TOPCon silver paste, characterized in that, The TOPCon silver paste, by weight, is composed of the following components: 40-70 parts silver powder, 5-25 parts silver-coated tungsten, 1-5 parts glass material, 1-5 parts modified nano calcium carbonate, 10-15 parts organic carrier, and 0.5-2 parts organic additives. The modified nano-calcium carbonate comprises: Nano-calcium carbonate, wherein the particle size of the nano-calcium carbonate is 10nm to 30nm; A silica layer is formed on the surface of the nano-calcium carbonate, and the thickness of the silica layer is 1-10 nm. A polyacrylic acid layer, wherein the polyacrylic acid layer covers the surface of the silica layer, and the thickness of the polyacrylic acid layer is 10-30 nm; The organic additives, by mass fraction, consist of the following chemical components: ammonium polyacrylate: 20-40%, cellulose ether: 10-30%, polyethylene glycol: 10-30%, benzotriazole: 10-30%, and silane coupling agent: 10-30%. The glass material, by molar percentage, comprises the following components: 50–70 mol.% lead borosilicate glass, 20–40 mol.% aluminosilicate glass, 1–3 mol.% bismuth oxide, 1–3 mol.% zinc oxide, 0.5–2 mol.% nano-silica, and 1–3 mol.% lanthanum oxide. The organic carrier, by mass fraction, is composed of the following chemical components: terpineol: 40-60%, ethyl acetate: 20-30%, polyether-modified siloxane: 1-5%, polyvinyl butyral: 10-20%, epoxy resin: 1-10%, and acrylic resin: 1-10%.

2. A method for preparing the low-corrosion TOPCon silver paste as described in claim 1, characterized in that, The method includes: The organic carrier is mixed with the organic additives to obtain a mixture; Silver powder, silver-coated tungsten, glass material, and modified nano-calcium carbonate are added to the mixture to obtain a mixed slurry; The mixed slurry is homogenized to obtain the TOPCon silver paste.

3. The method according to claim 2, characterized in that, The homogenization process includes the following parameters: homogenization pressure of 20-30 MPa, homogenization temperature of 40-60°C, and homogenization cycles of 2-5.

4. The method according to claim 2, characterized in that, The preparation method of the modified nano-calcium carbonate includes: The nano-calcium carbonate is subjected to low-temperature plasma treatment to form highly active groups on the surface of the nano-calcium carbonate, thereby obtaining the first active calcium carbonate. A silica layer is deposited on the surface of the first active calcium carbonate using atomic layer deposition technology to obtain the second active calcium carbonate; The second activated calcium carbonate was dispersed in an acrylic acid solution, and then ammonium persulfate was added to carry out an in-situ polymerization reaction to obtain the modified nano calcium carbonate.

5. The method according to claim 4, characterized in that, The mass ratio of the second activated calcium carbonate, the acrylic acid solution, and the ammonium persulfate is 100:(50-150):(0.5-2).

6. An application of the TOPCon silver paste as described in claim 1, characterized in that, The silver paste is used in TOPCon solar cells.

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