Enhanced antioxidant and size controllable Cu@Ag core-shell nanoparticles conductive inks for flexible printed electronics

Cost-effective Cu nanoparticles (NPs) for flexible electronics at low temperature sintering and in atmosphere conditions is difficult in response to their poor antioxidation. In this paper, a novel Cu@Ag core-shell nanoparticle with high antioxidant and size controllable characteristic using chemical reduction method was synthesized, and the corresponding conductive pastes by low temperature sintering was successfully applied to flexible printed electronics. The distinct thicknesses of Ag shell with the different [Cu]/[Ag] molar ratios were obtained. In contrast to sintering of conductive thin film of different thicknesses of Ag shell at low temperature, it is obvious that thicker Ag shell was beneficial for sintering densification and enhancing antioxidant, the corresponding resistivity significantly declined from 34.85μΩ•cm to 15.31μΩ•cm at 240°C. Besides, this air stable Cu@Ag NPs with excellent oxidation resistance were saved beyond 30 days and hardly oxidized during the process of sintering below 270°C. Finally, the flexible conductive thin film exhibited good bending-resistance with different bending radius and cycles under low sintering temperature, which has a promising potential to be applied for flexible printed electronics.