First-principles investigations of electronic and thermoelectric properties of Janus Al2SSe monolayer

Janus transition and post transition metal dichalcogenide monolayers such as MoSSe, WSSe, In2SSe, Ga2SSe etc. have shown tremendous potential for thermoelectric applications. The properties of these new materials have not been fully studied neither experimentally nor theoretically. We investigate the electronic and thermoelectric properties of Janus Al2SSe monolayer by performing first-principle calculations based on the Density Functional Theory and Boltzmann transport equations. Structural optimization reveals that Janus Al2SSe monolayer has a hexagonal structure similar to AlS and AlSe monolayers. The phonon dispersion curves establish the dynamic stability of this monolayer. Our electronic band structure calculations show that Al2SSe monolayer is an indirect band gap semiconductor having an energy band gap of 2.03 eV. We characterize the transport properties of this monolayer by evaluating them numerically. We find that both n-type and p-type Al2SSe monolayers are suitable for thermoelectric applications.