Optical Anisotropy in Tellurene and its Janus Allotropes -- A first principle Study

TL;DR

This study uses first-principles calculations to explore the structural, electronic, and optical properties of pristine and Janus tellurene allotropes, revealing tunable band gaps, optical anisotropy, and potential for device applications.

Contribution

It provides a comprehensive first-principles analysis of tellurene allotropes, highlighting the effects of Janus modifications on their electronic and optical properties for the first time.

Findings

Janus tellurene exhibits tunable band gaps and optical properties.

Optical anisotropy is present in all tellurene allotropes.

A Dirac cone-like feature is observed in pristine σ tellurene.

Abstract

Here, we present first principle study of structural, electronic, and optical properties of pristine and janus tellurene allotropes using density functional theory (DFT). The $\alpha$, $\beta$, $\delta$, and $\eta$ allotrope of pristine tellurene exhibit indirect band gap while $\gamma$ and $\sigma$ allotropes are metallic. The bandgap shows tunability in janus tellurene compared to pristine tellurene. A metallic to semiconductor transition occurs in janus $\gamma$, $\sigma$ and its allotropes. Dirac cone-like interesting feature has been observed for pristine $\sigma$ tellurene which remains preserved with the opening in energy gap for janus allotrope. In optical properties, imaginary part dielectric function and electron energy loss spectra show a blue shift in janus tellurene as compared to pristine form. Static dielectric constant is tunable in janus tellurene. All allotropes of tellurene are optically active in UV-Vis region with optical anisotropy in all three directions. We believe that our findings will provide useful pointers in the experimental fabrication of devices based on janus tellurene.