Enhanced thermoelectric performance from bulk to monolayer BiSbS3 from first principle study

The electronic structure and thermoelectric properties of bulk to monolayer BiSbS3 are studied by density functional theory and semi-classical Boltzmann transport equation. Meanwhile, it is clear that bulk and monolayer BiSbS3 are semiconductors with indirect band gaps by using the TB-mBJ scheme, respectively. Further, it can be known that the phonon spectrum of thin film BiSbS3 has no negative frequency, and it can be inferred further that thin film BiSbS3 is stable. Monolayer BiSbS3 studied in this paper has extremely low lattice thermal conductivity at room temperature, which is lower than that of single quintuple layer Bi2Te3, bulk Sb2Te3, single-QL Bi2Se3 and Bi2Te3S at room temperature. The maximum figure of merit of p-type monolayer BiSbS3 is obtained at a temperature of 1100 K and carrier concentration of 1 × 1020 cm−3. The optimal figure of merit, which is procured from n-type monolayer BiSbS3 within the range of carrier concentration interval considered in this paper, is obtained at 1500 K and 5 × 1019 cm−3.