Facile and scalable fabrication of self-assembled Cu architecture with superior antioxidative properties and improved sinterability as a conductive ink for flexible electronics

The inherent susceptibility to oxidation and poor sinterability significantly limit the practical application of Cu-based conductive inks. Most methodologies employed for the inks like organic polymer coatings and inorganic metal deposition are generally ineffective. Herein, we report the design of a novel hierarchical Cu architecture to simultaneously improve the antioxidative and sinterability via a self-passivation mechanism and loose interior structures. The hierarchical Cu architecture was prepared using copper hydroxide, L-ascorbic acid, and polyvinylpyrrolidone in aqueous solution; 40 g Cu were prepared in a scale-up experiment. A possible growth mechanism is proposed, involving the Cu2O-templated and mediated nucleation and growth of Cu nanocrystals, followed by the PVP-directed electrostatic self-assembly of Cu nanocrystals. The synthesized Cu shows high oxidation resistance after stored in ambient environment for 90 d by self-passivation, wherein the dense oxidized external layer prevented further oxidation of Cu, unlike other antioxidative strategies. In addition, the structure became 2D flake after a simple ball-milling for 10 min of 2000r, thus forming a good conductive network at the temperature of 180 °C. Importantly, no obvious decline in the electrical performance after severe surface oxidation. Although the structure cannot offer excellent conductive performance, but it proposes a new solution for the balance of antioxidative capabilities and good sinterability in Cu nanomaterials, thus facilitating greater utilization of Cu-based conductive inks for emerging flexible electronic applications.