Eur. Phys. J. Plus (2022) 137: 218
https://doi.org/10.1140/epjp/s13360-022-02442-y

Regular Article

Mechanical stability and electronic and optical properties of AA and AA${}^{{}^{\prime \prime }}$ Janus 1T PdXY (X, Y = S, Se, Te) bilayers

¹ Physics Department, Federal University of Rondônia, 76900-900, Porto Velho, Brazil
² Physics Department, Faculty of Science, King AbdulAziz University, 21589, Jeddah, Saudi Arabia

^a eamoujaes@unir.br

Received: 2 October 2021
Accepted: 1 February 2022
Published online: 10 February 2022

Abstract

Using first-principles calculations, we report the electronic, mechanical and optical features of 1T PdSSe, PdSTe and PdSeTe bilayers, belonging to the AA and AA${}^{{}^{\prime \prime }}$ stacking orders. Both AA and AA${}^{{}^{\prime \prime }}$ are exactly aligned and possess three types of interlayer chalcogenide planes; they, however, differ in the way the chalcogenides are superimposed in the two layers. With the spin-orbit coupling involved, the majority of the materials exhibit a semimetallic or a metallic nature, except for the two AA PdSSe bilayers with S-S and Se-Se interlayer planes, and the AA${}^{{}^{\prime \prime }}$ system with an S-Se interlayer plane; these are semiconductors of indirect bandgaps, not exceeding 0.51eV. All of the eighteen structures are mechanically stable, showing positive elastic constants. Along the parallel and perpendicular directions, and for the various regions of the electromagnetic spectrum, the absorption coefficient demonstrates high values . The maximum reflectivity of the materials is attained for the PdSSe AA bilayers with S-S interlayers, within the ultraviolet (UV) range; this makes it a suitable candidate for the fabrication of UV shields. Compared to their monolayer analogs, the bilayers show better absorption and reflectivity, throughout most of the electromagnetic spectrum. The disparate elastic and optical characteristics of the bilayer systems can provide hints that are essential for building robust optoelectronic devices and that can be tuned for various technological applications.