Computational Study Using Tight-Binding Propagation Method: Optical Properties of Defected WS2 Monolayer

Abstract

Materials computing is the interdisciplinary science of designing and investigating materials and their intrinsic properties through computational approaches. One promising material in the class of Transition Metal Dichalcogenides (TMDCs) is the monolayer of tungsten disulfide (WS₂), which has shown significant potential for applications in optoelectronics, including solar cell technology. While various experimental and theoretical studies have explored the optical properties of WS₂ monolayers, most have focused only on pristine structures or limited defect types. In this study, we investigate the influence of vacancy defects—specifically, different types and concentrations ranging from 1% to 5%—on the optical properties of WS₂ monolayers using the tight-binding propagation method implemented via the TBPLaS computational library. Our results show that both the type and concentration of vacancies significantly alter the absorption spectra and optical transitions, with distinct effects observed across different energy ranges. The presence of defects generally reduces optical performance in the visible range, potentially limiting solar cell efficiency. However, the defect-induced modifications in the infrared region suggest a new potential for WS₂ monolayers in infrared sensing applications.
Keywords: Tight binding, propagation method, WS2 monolayer, vacancies, optical properties