Optical anisotropy in bare and janus tellurene allotropes from ultraviolet to visible region: A first principle study

In this study, we report presence of optical anisotropy in very recently synthesized mono-elemental layered tellurene structures. Our results based on Density Functional Theory, reveal energetic and kinetic stability of five bare and janus tellurene allotropes. Graphene like tunable linear dispersion (Dirac cone) has been observed for σ tellurene. Optical response of bare and janus tellurene allotropes show that α, σ, γ allotrope are optically isotropic in nature whereas, β, δ and η allotropes are anisotropic. A blue shift in imaginary part of dielectric function and electron energy loss spectra has been observed for janus tellurene as compared to bare tellurene for E||c as well as E⊥c. The plasmon resonance have been observed about 7 eV in α, γ and η while β, δ, and σ show plasmon resonance above 10 eV. Tellurene mono-layers show optical anisotropy in UV–Vis region indicating its usefulness as photo-diodes, photo-catalysts, and photo-detectors.