First-principles study of electronic and optical properties of novel 2D TiOS monolayer and bilayer—Dimensionality reduction opens up a band gap in TiOS

• Published in: Results in physics 2023-05, Vol.48, p.106438, Article 106438
• Main Authors: Barhoumi, Mohamed, Said, Imen, Yedukondalu, N., Said, Moncef
• Format: Article
• Language: English
• Subjects: DFT; Electronic band structure; TiOS monolayer; TiOS/TiOS bilayer
• ISSN: 2211-3797; 2211-3797
• DOI: 10.1016/j.rinp.2023.106438

The finding of advanced functional materials with superior properties to existing ones to develop cutting-edge technologies for societal advancement is indispensable. We identify a new two-dimensional (2D) TiOS, which opens up a band gap due to the lowering of the dimensionality employing first-principles computations within the framework of density functional theory (DFT) and beyond. Electronic structure estimations reveal that bulk TiOS is metal whereas the 2D-TiOS possesses a band gap of ∼4.5 eV within GW approximation, which is higher than the band gap of 2D-InOF and 2D transition metal dichalcogenides. The computed phonon dispersion curves show that the 2D-TiOS is dynamically stable. The 2D-TiOS has a very high absorption coefficient in the 0–50 eV. Third-order elastic constants (TOECs) of this 2D-TiOS are achieved using DFT and within the adiabatic-connection fluctuation–dissipation theorem in the random phase approximation. Surprisingly, we find a band overlap, indicating that TiOS/TiOS bilayer is a metal. If the incident light frequency surpasses the plasma frequency (60.00 eV), and then the bilayer turns out to be transparent. Our findings suggest that this 2D sheet is a promising alternative for nanotechnology and optoelectronic devices. •We investigate the electronic and optical properties of novel TiOS material.•TiOS is dynamically stable.•TiOS has a high absorption coefficient in the range of 0–50 eV.•SOECs and TOECs of 2D-TiOS are accomplished.