A bimodal core–shell structured Cu–Ag nanoparticles based conductive ink capable of low temperature sintering for printed flexible electronics

In this study, the bimodal sized core-shell structured Cu-Ag nanoparticles (Cu@Ag NPs) of 20 and 110 nm were prepared using lactic acid as stabilizer. The Cu oxides were removed during the formation process of Ag shell. The obtained Cu and Cu@Ag NPs exhibit good oxidation resistance at temperatures below 150 and 200 °C, respectively. A conductive ink with a metal loading of about 50 wt.% was formulated for screen printing by mixing synthesized Cu@Ag NPs, ethyl cellulose and terpineol. The bimodal Cu@Ag NPs based ink shows low resistivity of 4×10
^-6
and 8.5×10
^-7
Ω·m after sintering at 120 and 200 °C, respectively, for 30 min in the atmosphere of nitrogen. In addition, a possible mechanism has been proposed to illustrate the sintering process of Cu@Ag NPs.