Electronic, optical, and thermoelectric properties of Janus In-based monochalcogenides

Inspired by the successfully experimental synthesis of Janus structures recently, we systematically study the electronic, optical, and electronic transport properties of Janus monolayers In 2 XY ( X / Y = S, Se, Te with X ≠ Y ) in the presence of a biaxial strain and electric field using density functional theory. Monolayers In 2 XY are dynamically and thermally stable at room temperature. At equilibrium, both In 2 STe and In 2 SeTe are direct semiconductors while In 2 SSe exhibits an indirect semiconducting behavior. The strain significantly alters the electronic structure of In 2 XY and their photocatalytic activity. Besides, the indirect-direct gap transitions can be found due to applied strain. The effect of the electric field on optical properties of In 2 XY is negligible. Meanwhile, the optical absorbance intensity of the Janus In 2 XY monolayers is remarkably increased by compressive strain. Also, In 2 XY monolayers exhibit very low lattice thermal conductivities resulting in a high figure of meri ZT , which makes them potential candidates for room-temperature thermoelectric materials.