Direct laser writing of copper-graphene composites for flexible electronics

Copper-graphene composites have potential applications in flexible electronics due to their unique three-dimensional porous structure, high specific surface area, high electrical conductivity and electrochemical properties. Here, a simple room temperature fabrication method for conductive copper-graphene composites on different substrates, such as glass and polycarbonate, using direct laser writing process without pre-synthesis of copper nanomaterials and graphene flakes is presented. This process uses copper ion precursor and laser to generate copper nanoparticles and in-situ join them to form a network structure. Meanwhile, graphene also can be synthesized and coated on copper networks. The as-prepared copper-graphene composites are highly conductive and electrochemically active for thin conductive film and electrodes of supercapacitor. The composite film has a sheet resistance of 0.57Ω sq⁻¹ and the capacitance of as-written copper-graphene all-solid-state flexible micro-supercapacitor is 13.2mF cm⁻² at a current density of 0.5mA cm⁻². This simple and low temperature process for composite structures will enable the rapid fabrication of flexible devices with low cost.