Computational Study of Thermal Transport in Nanowire-Graphene Thin Films

Metal nanowires-doped polycrystalline graphene is recently shown to be very promising as transparent conducting material for many applications including solar cells, touchscreens, and light-emitting diodes. However, the thermal reliability of these thin-film materials can be a concern and is not well understood yet. In this study, we develop and utilize a coupled electrothermal model to examine self-heating in the nanowire-polygraphene thin-film hybrid material. We study the effects of various key material/topological parameters such as nanowire density and alignment, and interfacial thermal resistances at nanowire junctions, and nanowire-graphene interfaces on the temperature distribution of both nanowire network and polygraphene. The analysis provides useful insights about the size, location, and number of hotspots in the nanowires and polygraphene. The peak and average temperature variation in the thin-film material are explored and analyzed for varied nanowire density and percentage of high-resistance grain boundaries, and, in this respect, we observe that the variation of both peak and average temperature of the nanowire network deviates from the classical behavior expected from an electrical conductor, and rather it follows the trend according to the copercolating charge transport within the nanowire-polygraphene hybrid material. We find that the temperature profile of nanowires follows the Weibull distribution for various current values in the network for both below and above percolation threshold of nanowire networks. We systematically study the effect of nanowire orientation on the temperature profile in the material, and find that aligned nanowires along the main transport direction is likely to experience higher temperature rise due to the enhanced current. The developed framework can help us to provide design guidelines to mitigate the bottlenecks and accelerate the advent of these types of hybrid materials as transparent conducting electrodes.