Investigation for Thermoelectric Properties of the MoS Monolayer-Graphene Heterostructure: Density Functional Theory Calculations and Electrical Transport Measurements.

We investigated the thermoelectric (TE) properties of the MoS monolayer-graphene heterostructure which consists of the MoS monolayer and graphene. The electronic structures of the MoS monolayer-graphene heterostructure are mainly contributed from graphene and the MoS monolayer for the valence band maximum and conduction band minimum, respectively. The change in the electronic structures near the Fermi level is responsible for the fact that the calculated Seebeck coefficients and electrical conductivity σ/τ of MoS monolayer-graphene are largely affected from those of graphene and the MoS monolayer. Its power factor σ/τ is increased compared to those of graphene and the MoS monolayer at an electron concentration of 10 to 10 cm, which corresponds to a three-dimensional concentration of 3 × 10 to 3 × 10 cm. We also demonstrated that the MoS monolayer shows the p-type TE behavior, while the MoS monolayer-graphene heterostructure is given to the n-type TE material. The current study provides a strategy to improve TE properties of the MoS monolayer through the formation of the MoS monolayer-graphene heterostructure.