A novel method to prepare Cu@Ag core–shell nanoparticles for printed flexible electronics

This paper presents a one-step synthetic method of Cu@Ag core–shell nanoparticles with high oxidation resistance and electrical conductivity for printed electronics on flexible substrates. To obtain a homogeneous Ag coating on Cu nanoparticles, various Cu–Ag nanoparticles were synthesized with the change of [Cu]/[Ag] molar ratio using modified wire evaporation method. The structure and composition analyses of the synthesized Cu–Ag nanoparticles were performed using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The Cu@Ag core–shell nanoparticles prepared at the optimum [Cu]/[Ag] molar ratio were dispersed in ethylene glycol and the nanoink was coated on a polyimide film using a screen-printing method. The Cu@Ag film sintered at 200 °C exhibited an electrical resistivity of 8.2 μΩ·cm, which was much lower than the reported values for the Cu@Ag films prepared by chemical reduction or electrochemical deposition method.