Thermoelectric properties of the SnS monolayer: Fully ab initio and accelerated calculations

An energetic and dynamical stability analysis of five candidate structures-hexagonal, buckled hexagonal, litharge, inverted litharge, and distorted-NaCl-of the SnS monolayer is performed using density functional theory. The most stable is found to be a highly distorted-NaCl-type structure. The thermoelectric properties of this monolayer are then calculated using the density functional theory and the Boltzmann transport equation. In terms of phonon scattering, there is a sharp contrast between this monolayer and bulk materials, where normal processes are more important. The calculations reveal that the SnS monolayer has enhanced electrical performance as compared to the bulk phase. As a consequence, high figures of merit ZT similar to 5 and ZT similar to 1.36 are predicted at 600 and 300 K, respectively, for the monolayer, similar to 33 times higher than the ZT of its bulk analog. Therefore, this structure is an interesting candidate for room-temperature thermoelectric applications. A comparison between the fully ab initio results and simpler models based on relaxation times for electrons and phonons highlights the efficiency of computationally inexpensive models. However, ab initio calculations are found to be very important for the prediction of thermal transport properties.

Automated summary

An energetic and dynamical stability analysis was conducted on five candidate structures of the SnS monolayer, with the highly distorted-NaCl-type structure found to be the most stable. The monolayer exhibited enhanced electrical performance compared to bulk materials, with significantly higher ZT values predicted. Computational inexpensive models were shown to be efficient, but ab initio calculations remained crucial for predicting thermal transport properties.