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

Abstract

Inspired by the successfully experimental synthesis of Janus structures recently, we systematically study the electronic, optical, and electronic transport properties of Janus monolayers In2XY (X/Y = S, Se, Te with X ≠ Y) in the presence of a biaxial strain and electric field using density functional theory. Monolayers In2XY are dynamically and thermally stable at room temperature. At equilibrium, both In2STe and In2SeTe are direct semiconductors while In2SSe exhibits an indirect semiconducting behavior. The strain significantly alters the electronic structure of In2XY 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 In2XY is negligible. Meanwhile, the optical absorbance intensity of the Janus In2XY monolayers is remarkably increased by compressive strain. Also, In2XY monolayers exhibit very low lattice thermal conductivities resulting in a high figure of merit ZT, which makes them potential candidates for room-temperature thermoelectric materials.