Optimising the thermoelectric properties of SnTe by band engineering

Abstract

SnTe, the lead-free and environmentally friendly material, has gained recognition as a low band-gap thermoelectric material. However, it encounters challenges due to the presence of a significant concentration of intrinsic tin vacancies and its extremely small band gap of 0.18 eV. These factors contribute to a low Seebeck coefficient (S) and high electronic thermal conductivity. These challenges can be overcome by tuning the band gap of SnTe which enhance its thermoelectric behaviour. In our study, we investigate the thermoelectric properties of the bulk SnTe by systematically increasing the band gap while keeping the carrier concentration fixed. By varying the band gap from 0.14 to 0.8 eV, we observe significant enhancements in the thermoelectric performance of the material. Specifically, the power factor reaches a value of 420 \(\upmu \)W cm\(^{-1}\) K\(^{-2}\) and the electronic thermal conductivity decreases to 2.3 W m\(^{-1}\) K\(^{-1}\) when the band gap is 0.8 eV and the carrier concentration is \(10^{18}\) cm\(^{-3}\). Moreover, the figure of merit (ZT) value of SnTe can be improved up to 15 times. This study can motivate further experimental investigation on interesting compounds.