Ab initio prediction of enhanced thermoelectric performance from bulk to monolayer Sb2S2Te

Abstract

By using the first principles investigations based on the full potential linearized augmented plane wave (FP-LAPW) method within both the generalized gradient approximation (GGA) and the Tran-Blaha modified Becke-Johnson (TB-mBJ), we predicted the electronic structure and thermoelectric properties of bulk and monolayer Sb2S2Te. Both monolayer and bulk structures of Sb2S2Te are semiconductors with an indirect band gap. The band gap can be improved with TB-mBJ. The effect of charge carriers concentration on the electrical conductivity (σ) and the electronic thermal conductivity (κeκe) for bulk Sb2S2Te has reached the level of saturation. The monolayer Sb2S2Te exhibits superior thermoelectric properties and plays a key role in the enhancement of the figure of merit for p-type doping in comparison to the bulk compound. Monolayer Sb2S2Te have ultra-low lattice thermal conductivity and larger thermoelectric (TE) figure of merit ZT. The results demonstrate that the monolayer Sb2S2Te could be potential candidate for TE applications, which has promising TE properties in p-type system.