Influence of heat transfer at the graphene–polyimide interface on laser-induced graphene formation

Laser-induced graphene (LIG) provides a three-dimensional porous structure of graphene, which is suitable for application to energy storage devices and flexible electronics. Controlling the morphology and structure of LIG and understanding its underlying principle are important for enhancing the performance of LIG-based devices. Here, we investigated the effects of graphene interfacing with a precursor material on the LIG formation. A CO2 laser with different powers and scan rates was irradiated on a polyimide film covered with mono-, bi-, and trilayer graphene to fabricate in situ LIG contacts. As the number of graphene layers increases, the threshold energy required for the LIG formation decreases. In addition, the interfacing graphene causes spreading and smoothing of the LIG electrodes in the in-plane direction. A numerical study on the effect of the interfacing graphene on heat transfer was also conducted. The simulation results showed that the graphene layer enhances thermal diffusion to facilitate the LIG formation; this was also observed in the experimental results. Our study on the interfacial effects of a nanomaterial on the LIG formation provides design guidelines for considering heat transfer in LIG electronics fabricated with heterogeneous materials and structures.