Structural, electronic and optical properties of two-dimensional Janus transition metal oxides MXO (M=Ti, Hf and Zr; X=S and Se) for photovoltaic and opto-electronic applications.

Two-dimensional Janus transition metal dichalcogenides structures have drawn increasing importance due to their remarkable properties for versatile applications in optoelectronic, photo-catalytic, thermo-electricity, piezoelectricity and spintronic. In this Paper, by employing the Ab-initio computations based on the density functional theory, the structural, electronic and optical properties of Janus MXO (M = Ti, Hf and Zr; X = S and Se) mono-layers are investigated utilizing full potential linearized augmented plane waves (FP-LAPW) method. The lattice parameters of the six Janus were computed, which are close to the previous theoretical results. The density of states and the electronic band structures were investigated for the first time using (GGA-PBE) approximation for the potential of the exchange and correlation. The optical parameters like complex dielectric function, refractive index, reflectivity, extinction and absorption coefficients of all Janus were performed. Our results reveal strong absorption coefficient and low reflectivity in the visible and ultraviolet regions, which make them candidates for opto-electronic and photovoltaic applications. Image 1 • Janus transition metal oxides adopt a similar structure as transition metal dichalcogenides with MX 2 formula. • TiSO mono-layer is a semiconductor with a direct band gap. • Low reflectivity is observed for all MXO nanosheets. • Refractive index, extinction coefficient and optical conductivity are calculated. • All MXO mono-layers exhibit strong absorption coefficient in the visible and ultra-violet regions. [ABSTRACT FROM AUTHOR]