Nano Letters (2011)

Graphene exhibits the highest thermal conductivity ever observed. Its thermal transport has been studied theoretically and experimentally, mostly in single-crystalline graphene. Unfortunately, large-scale growth, for example by chemical vapour deposition (CVD), usually yields polycrystalline sheets. Akbar Bagri and colleagues have performed molecular dynamic simulations of the thermal transport across various grain boundary orientations in graphene. They assumed a constant heat flow through the material, calculated the temperature profile and from that estimated the thermal conductivity. Interestingly, they found abrupt jumps in the temperature at the grain boundaries, which depend on the boundary orientation and grain size. The estimated grain boundary thermal conductivity is much higher than in the case of other materials with high thermal conductivity, such as nanocrystalline diamond. The results are particularly important in view of potential applications based on CVD-grown graphene. It will be interesting to see how the experiments will compare with these predictions.