Graphene addition improved figure of merit in SnTe prepared by the rapid hybrid microwave solid-state method

Abstract

We successfully synthesised SnTe-based powders (SnTe, Sn0.95Bi0.05Te, and SnTe with graphene addition) by a hybrid microwave solid-state method. This demonstrated comparable thermoelectric performance to the conventional heating method but had low energy consumption and rapid synthesis. Graphene addition to SnTe materials resulted in significant reduction of thermal conductivity. The SnTe with 5 wt% graphene exhibited a reduction in overall thermal conductivity from ∼10 W m−1 K−1 for SnTe to ∼2 W m−1 K−1 at 325 K and showed a moderate power factor. The Debye model was used to explain the origin of the effects of graphene on lattice thermal conductivity. The dimensionless figure of merit was increased by five times, from 0.07 for SnTe to 0.35 for SnTe with 5 wt% graphene. Our results demonstrated an effective method and additive material to synthesise and enhance the thermoelectric properties of SnTe materials.