Abstract:Surface organic coating represents a pivotal technology for enhancing the performance of silver-coated copper (Cu@Ag) powder and its corresponding paste. However, the adsorption behavior of coating agents on the powder surface and their underlying mechanisms governing the properties of the powder, paste, and the overall performance of solar cells remain to be systematically investigated. In this study, octadecyltrimethoxysilane (ODTMS) was employed as the coating agent for Cu@Ag powder, with varying dosages of ODTMS used to fabricate Cu@Ag pastes. The application efficacy and action mechanisms were explored using silicon heterojunction (SHJ) solar cells as a model system. The results indicate that ODTMS treatment enhances the hydrophobicity of Ag-Cu powder, elevating its oxidation onset temperature from 250.00°C to 297.33°C. An optimal dosage of ODTMS improves powder dispersibility and resin distribution, leading to reduced bulk resistivity and contact resistivity of the cured metal electrodes on the cells, as well as a slight increase in the open-circuit voltage (VOC) of the devices. When the ODTMS dosage reaches or exceeds 0.08%, the formation of a Si-O-Si network on the Cu@Ag powder surface progressively degrades the electrical conductivity of the electrodes, moreover, a gradual decrease is also manifested in VOC and fill factor(FF) of the SHJ cells. The printed line width of ODTMS-treated samples is marginally larger than that of untreated sample, but the difference is negligible among the treated samples, resulting in no significant variation in short-circuit current density (JSC). Ultimately, the SHJ solar cells achieve the highest conversion efficiency when the ODTMS dosage is 0.04%.