One-step selective laser patterning of copper/graphene flexible electrodes

Flexible electrodes have attracted much attention in consumer electronic applications. In this work, laser direct writing is used to fabricate copper/graphene composite electrodes on a flexible substrate in one step. This direct writing process with a low power laser can reduce copper ions in thin films to form copper nanomaterials and spontaneously interconnect them to gain good conductivity, while the laser also induces the growth of multi-layer graphene that coats on copper to improve the oxidation resistance of electrodes. The electrical performance and chemical composition of flexible electrodes can be tuned by laser power, scanning speed, and defocus distance. A mechanism of in situ reduction and interconnection of copper nanomaterials during laser direct writing has been proposed. This method could largely reduce the oxidation issue by avoiding synthesis and sintering processes of copper nanomaterials. These as-written copper electrodes have good stability and have potential applications in flexible electronics, such as flexible heaters or antennas as demonstrated.