Maximum Thermoelectric Power Factor and Optimal Carrier Concentration of Bilayer Graphene at Various Temperatures

The thermoelectric response of bilayer graphene over a wide temperature range (0 < T <= 400 K) was theoretically investigated using linear response theory combined with a Green's function technique. We found that the power factor PF for a fixed chemical potential mu exhibits a maximum at a certain T. On the other hand we found that the PF for a fixed T exhibits a maximum (PFmax) at an optimal mu [or optimal carrier concentration (n(opt))]. In addition, we clarified the T dependence of n opt and PFmax and explained the existence of n(opt) in terms of the thermal excitation of electrons between the valence and conduction bands, which cannot be predicted by the conventional Mott formula.