Prediction of two-dimensional bismuth-based chalcogenides Bi <sub>2</sub> X <sub>3</sub> (X = S, Se, Te) monolayers with orthorhombic structure: a first-principles study
A. Bafekry, Mehrdad Faraji, Mohamed M. Fadlallah, Hamad Rahman Jappor, Nguyen N. Hieu, Mitra Ghergherehchi, S. A. H. Feghhi, D. Gogova
Abstract
Abstract First-principles calculation is a very powerful tool for discovery and design of novel two-dimensional materials with unique properties needed for the next generation technology. Motivated by the successful preparation of Bi 2 S 3 nanosheets with orthorhombic structure in the last year, herein we gain a deep theoretical insight into the crystal structure, stability, electronic and optical properties of Bi 2 X 3 (X = S, Se, Te) monolayers of orthorhombic phase employing the first-principles calculations. The Molecular dynamics study, phonon spectra, criteria for elastic stability, and cohesive energy results confirm the desired stability of the Bi 2 X 3 monolayers. From S, to Se and Te, the work function value as well as stability of the systems decrease due to the decline in electronegativity. Mechanical properties study reveals that Bi 2 X 3 monolayers have brittle nature. The electronic bandgap values of Bi 2 S 3 , Bi 2 Se 3 and Bi 2 Te 3 monolayers are predicted by the HSE06 functional to be 2.05, 1.20 and 1.16 eV, respectively. By assessing the optical properties, it has been found that Bi 2 X 3 monolayers can absorb ultraviolet light. The high in-plane optical anisotropy offers an additional degree of freedom in the design of optical devices. The properties revealed in our survey will stimulate and inspire the search for new approaches of orthorhombic Bi 2 X 3 (X = S, Se, Te) monolayers synthesis and properties manipulation for fabrication of novel nanoelectronic and optoelectronic devices.