Thermoelectric properties of the Janus PtSTe monolayer compared with its parent structures
Lijun Pan, Zhao Wang, Jesús Carrete, Georg K. H. Madsen
Abstract
We use ab initio calculations to study phonon and charge-carrier transport in the Janus $\mathrm{PtSTe}$ monolayer, a lower-symmetry derivative of quasi-two-dimensional transition metal chalcogenides, with a view to characterizing its thermoelectric performance. For the sake of comparison, we also perform the same study on its parent structures, ${\mathrm{PtTe}}_{2}$ and ${\mathrm{PtS}}_{2}$. We find a significantly increased thermoelectric figure of merit, driven by modest increases in the Seebeck coefficient but, most importantly, by a drastic reduction in the thermal conductivity. We show that this decrease cannot be explained by a simple inspection of the phonon band structure; instead, it has its roots in a relaxation of the selection rules for three-phonon scattering as a result of the broken symmetry of the Janus structure. This suggests that Janus monolayers have a significant intrinsic advantage and untapped potential for thermoelectric applications among quasi-two-dimensional systems.