Vanadium Dichalcogenides Triangular Nanoflakes: A Comparative Study of Optical and Electronic Properties

In this work, we comparatively studied the electronic and optical properties of triangular-shaped nanoflakes of VX2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_2$$\end{document} with varying flake sizes and compositions. We calculated the electronic properties using the density functional theory (DFT) while employing the time-dependent density functional theory (TD-DFT) to explore the optical properties of nanoflakes. The density of states (DOS) of VX2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_2$$\end{document} triangular nanoflakes showed the existence of localized metallic states, primarily originating from the presence of edge atoms in the flake. The optical spectra of VX2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_2$$\end{document} triangular nanoflakes revealed that the discrete peaks at low energy levels show broadening as flake size increases while splitting in resonance peaks upon changing the composition of the nanoflake. To gain insights into the nature of photoabsorption peaks, we analyzed the induced density and transition contribution map (TCM), which revealed the presence of both single-particle excitations and collective excitations. The collective excitations are known as plasmons which arise from the localized metallic edge states of the nanoflakes. This study sheds light on how nanoflakes’ electronic and optical characteristics depend heavily on their shape, size, and composition. Future experiments are necessary to validate these theoretical findings.