One-Step Fabrication of Copper Electrode by Laser-Induced Direct Local Reduction and Agglomeration of Copper Oxide Nanoparticle

Copper oxide (CuO) nanoparticle-based organic solutions are highly stable in air as well as cheaper compared to copper (Cu) nanoparticle solutions due to the absence of particle oxidation problems. Laser direct patterning via photothermochemical reaction of the CuO nanoparticles is suggested to efficiently fabricate Cu electrodes. CuO nanoparticles dispersed in ethylene glycol were instantaneously reduced to Cu nanoparticles by intense laser irradiation, and the Cu nanoparticles were simultaneously agglomerated and sintered to form conductors without additional processes. Finally, Cu electrodes with about 10 μm thickness and a specific electrical resistance of 31 μΩ·cm were successfully fabricated on a glass and flexible substrate. Furthermore, the maximum possible patterning rate was discussed in terms of the reduction rate of CuO. This conductor structuring method enables an environmentally friendly and cost-effective process as well as a low-temperature manufacturing sequence to realize large-area, flexible electronics on polymer substrates.