Effect of defects on graphene thermoelectric properties

The thermal conductivity must be reduced to apply graphene as thermoelectric devices. Because the main heat carrier in graphene is phonon, introducing defects into graphene affects the phonon propagation in graphene, resulting in the change in the thermal conductivity. Here we investigate the effect of defects induced by oxygen plasma treatment on the thermoelectric property of graphene. The thermoelectric power of graphene with defects gradually decreases with increasing the density of defects compared to that of pristine graphene. Although defects degrade the electronic transport, leading to the reduction in both the thermoelectric power and electrical conductivity, the thermal conductivity is more reduced. As a consequence, graphene with defects shows higher thermoelectric figure of merit. This suggests that the performance of graphene-based thermoelectric devices can be enhanced more effectively by introducing defects in graphene.