Theoretical insights into the thermoelectric transport performance of the MoPGaS monolayer.

Since the MoSiN monolayer was synthesized experimentally, the family of 2D septuple-layer MoSiN-like materials have attracted widespread attention. However, to date, research on such materials in the thermoelectric field has been rarely reported. In this work, combining first-principles calculations and Boltzmann transport equations, we have investigated the electronic and thermal transport properties of the MoPGaS monolayer. The analysis of the phonon spectrum proves that the MoPGaS monolayer is dynamically stable. The inherent low thermal conductivity of MoPGaS of 0.55 W m K is mainly attributed to the anticrossing behavior of longitudinal acoustic phonons and low-frequency optical phonons, resulting in strong phonon-phonon scattering. The high Seebeck coefficient of 1190 μV K with a high power factor illustrates that MoPGaS exhibits excellent electronic transport properties. Furthermore, the increase in temperature promotes the electrical transport while reducing the thermal conductivity. The present work demonstrates that the MoPGaS monolayer exhibits excellent thermoelectric performance and provides a new perspective for the research of septuple-layer materials in the thermoelectric field.