Silver@carbon core-shell nanocomposites: a novel approach for low-cost, high-performance photovoltaic silver pastes

This study presents a silver@carbon (Ag@C) core-shell nanostructure synthesized via a one-pot hydrothermal method, in which glucose serves as both a reducing agent and carbon source, aiming to reduce the high cost of silver in photovoltaic (PV) pastes. The as-prepared Ag@C nanoparticles exhibit a uniform size of approximately 60-90 nm, a carbon shell thickness of 5 nm, and a carbon content of about 15.2 wt%. When incorporated into PV paste with a total silver loading of 69 wt% (a 13% reduction compared to pure Ag paste), the Ag@C-based paste exhibits a sheet resistance of 35.2 mΩ sq^-1 and a contact resistivity of 2.6 mΩ cm². These values are superior to those of a pure Ag paste (38.5 mΩ sq^-1 and 3.1 mΩ cm²) and approaching the performance of commercial paste (24.8 mΩ sq^-1 and 1.7 mΩ cm²). Notably, this corresponds to a 13.6% reduction in the silver proportion within the Ag@C composite compared to pure Ag (84.8 wt% Ag vs. 100 wt% Ag), and approximately 23% reduction in total Ag content compared to the commercial reference. Electrochemical measurements indicate a low charge transfer resistance of 12.3 Ω cm² and great corrosion resistance, with a corrosion current density of 0.38 µA cm^-2. Furthermore, under sulfurization (50 ppm H₂S, 72 h) and damp-heat (85 °C/85% RH, 1000 h) conditions, the Ag@C electrode shows resistance increases of less than 10% and 15%, respectively, significantly outperforming pure Ag. These results demonstrate a promising strategy for achieving cost-effective and highly reliable PV metallization.