University of Oulu

J. Phys. Chem. C 2023, 127, 34, 17029–17038,

Novel metalless chalcogen-based Janus layers : a density functional theory study

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Author: Vallinayagam, M.1; Sudheer, A. E.2; Aravindh, S. Assa3;
Organizations: 1TU Bergakademie Freiberg, Leipziger Straße 23, D-09596 Freiberg, Germany
2Indian Institute of Information Technology Design and Manufacturing, 518008 Kurnool, India
3Nano and Molecular Systems Research Unit, Pentti Kaiteran katu 1, 90570 Oulu, Finland
4The Institute of Mathematical Sciences, C.I.T. Campus, Taramani, 600113 Chennai, India
5Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, 01328 Dresden, Germany
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3.5 MB)
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Language: English
Published: American Chemical Society, 2023
Publish Date: 2023-10-30


The electronic, thermodynamic, and optical properties of a new type of two-dimensional Janus layer (JL) consisting exclusively of chalcogens are investigated using first-principles calculations. The permutations on atomic sites provide increased stability due to the multi-valency of chalcogens, and a heavier central atom further stabilizes the layer due to the increased coordination number. The investigated JLs are indirect bandgap materials with a bandgap larger than 1.23 eV, making them suitable for photocatalytic activity. Different feasible chemical potentials are analyzed, and chalcogens’ poor limits are proposed to fabricate the JLs. Based on the comparison of the formation energy, the energetic profile of the JLs is identified as EfTeSeS < E fSSeTe < EfSeSTe, irrespective of the chemical potentials of chalcogen. Hence, TeSeS is more stable than the JL arrangements SSeTe and SeSTe. The flat bands around the Fermi energy level and the reduction in path length between the maximum of conduction and minimum of valence bands explain the magnitude of multiple peaks observed in the optical spectra of the JLs. These absorptions turn the studied JLs into potential candidates for water splitting. The optimized bandgap reveals that the band edges efficiently straddle the water redox potentials at different pH levels. In addition, the positive vibrational frequencies depict the stability of these layers. Because of the minimal formation energy requirement, higher density of states around the Fermi level, as well as enhanced optical absorption compared to other JL, TeSeS JLs may lead to enhanced performance in photovoltaic and photocatalytic applications. These results add new members to the JL family of pure chalcogens and pave the way toward novel materials for respective applications.

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Series: The journal of physical chemistry. C
ISSN: 1932-7447
ISSN-E: 1932-7455
ISSN-L: 1932-7447
Volume: 127
Issue: 34
Pages: 17029 - 17038
DOI: 10.1021/acs.jpcc.3c02248
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
Funding: M.V. and M.Z. acknowledge funding by the DFG within the project DFG 442646446, ZS 120/5-1.
Copyright information: © 2023 The Authors. Published by American Chemical Society. This publication is licensed under CC-BY 4.0.