Rapid dry synthesis and maskless patterning of transparent graphite microelectrodes

Micro-patterned, transparent graphene is highly sought after for a wide range of applications in fields such as solar technology, sensing, and biomedical devices. Laser-induced graphitisation (LIG) provides a dry synthesis and customisable alternative to current multi-step, wet-chemical graphene synthesis techniques. However, contemporary LIG techniques produce opaque electrodes with limited micro-scale patterning resolution. Here we outline a LIG based approach for application specific transparent electrode fabrication at macro and micro scales. Precursor plasma enhanced chemical vapour deposition based a-C:N:H nano-films were subjected to 10 ps pulsed laser exposure that produced regions with conductivities up to 14.2 Scm − 1 and transmission of 70%. Characterisation of the film transformation as a function of incident laser fluence was carried out via single and multi-pulse ablation studies. Scalability of the technique is demonstrated with processing parameter windows of trace speed, pulse overlap, and hatch pattern explored as a function of accumulated scan fluence. The film modification stages throughout the graphitisation process are divided into four regimes with distinct surface topologies, enabling control of electrode roughness in a single processing step. The combination of picosecond processing with a-C:N:H precursor films forms an dry, low cost, and customisable fabrication method for transparent micro-scale graphite electrodes. • Complete dry synthesis fabrication of patterened graphite at microscale resolution. • Tunable optical transparency of electrodes with incident laser fluence. • Variable surface roughness of the resulting graphite with different accumulated scan fluence.