Cost-Effective Metallization of N-Type TOPCon Solar Cells Using Ag-Coated Copper Paste

The incorporation of Ag-coated copper (Cu) paste in the metallization of commercial PERC, TOPCon, and back-contact silicon solar cells is often hindered by high-temperature firing requirements that promote copper oxidation. Such oxidation can increase series and contact resistances, reducing the fill factor (FF), while copper diffusion into the silicon substrate can degrade the open-circuit voltage (VOC). In this study, we explore the use of Ag-coated Cu paste as the rear electrode material in n-type TOPCon solar cells. Our results indicate that, under a controlled laser contact opening, low-temperature curing, and laser-assisted firing process, the Ag-coated Cu paste achieves minimal contact resistivity and maintains VOC. A fill factor of 81.43%, a contact resistivity of 2.32 mΩ•cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, and a cell efficiency of 24.24% were attained. Notably, incorporating Ag-coated Cu paste on the rear electrodes reduces silver consumption by 40–60% relative to conventional silver pastes, while retaining comparable cell performance.