Contribution of holes to the thermoelectric properties of gated bilayer graphene junctions

Abstract

The study of 2D materials in renewable energies has been of great interest due to the growing demand for energy generation without affecting the environment. This includes 2D materials such as bilayer graphene in the context of thermoelectricity. Here, we study the thermoelectric properties of bilayer graphene junctions, in particular, the Seebeck coefficient, power factor, and figure of merit in single and double junctions as well as superlattices. We employ the hybrid matrix method and the Landauer-Bütikker formalism. We pay special attention to the contribution of holes to the mentioned thermoelectric properties. We find that the accessibility of the holes as well as the thermal activation of the charge carriers have a considerable impact on the Seebeck coefficient, power factor, and figure of merit around the bilayer graphene charge neutrality point. In particular, the thermoelectric properties at low temperatures improve when the hole contribution is taken into account. The thermal activation of the charge carriers in conjunction with the accessibility of the holes give rise to a reduction of the thermoelectric properties. In short, our findings indicate that the contribution of holes is fundamental in shaping the thermoelectric properties of bilayer graphene junctions around the charge neutrality point.