Relationship between electrical and thermal conductivity in graphene-based transparent and conducting thin films

We measured and modeled the electrical, optical and thermal properties of transparent and conducting thin films based on graphene and graphitic platelets. Thermal conductivity of our films decreases with increasing electrical conductivity. Our experiments indicate that, for sufficiently large platelets, the influence factor in controlling the thermal conductivity is represented by the junctions between neighboring graphene platelets. The thickness of such junctions is determined by the average number of graphene layers (N) forming each platelet. The fact that both the thermal and electrical properties depend on N allows us to establish a model that leads to a theoretical relationship between the thermal and electrical conductivity in our samples, which is general enough to be applied to a large class of graphene-based thin films.