Sintering mechanism of size-controllable Cu-Ag core–shell nanoparticles for flexible conductive film with high conductivity, antioxidation, and electrochemical migration resistance

Metallic conductive nanoink with the sensitivity of temperature, oxygen, and electrochemical migration is a great challenge for printed electronics. Here, the size-controllable Cu@Ag core–shell nanoparticles (NPs) conductive films with effective cost, excellent electrical conductivity, high electrochemical migration (ECM) and oxidation resistance were obtained successfully. The novel mechanism of lower temperature sintering for Cu@Ag NPs was proposed due to radius of curvature between a large amount of tiny Ag nanobumps generated by ‘dewetting’ behavior. The Cu@Ag NPs also exhibited extreme ECM and oxidation resistance. It could remain steady in air for 40 days and hardly oxide at a high temperature of 156℃, and its failure time of ECM was 4.6 times higher than that of Ag NPs. Besides, the resistivity was up to 3.21 μΩ∙cm (55% of the bulk conductivity of Cu) even sintered at 140 °C, which enjoyed a great advantage. Ultimately, serial flexible organic light emitting diodes were integrated by high precision inkjet printing, and their excellent bending resistance and printable performance were fully exhibited. Accordingly, integrating the advantages of controllable nanoscale, lower temperature sintering, optimized conductivity, high antioxidation, excellent ECM resistance, flexibility, and printability, we enlighten the practical applications of flexible printed electronics.