Halogenated Graphdiyne and Graphyne Single Layers: A Systematic Study

Abstract

Graphyne and graphdiyne families of flat carbon (sp²/sp) networks with high degrees of π-conjunction are attracting much attention due to their promising electronic, optical, and mechanical properties. In the present investigation we have studied the structural, mechanical, electrical and optical properties of halogenated graphdiyne and graphyne. The optical spectra of pure and halogenated structures are calculated. The optical absorption is dominated by excitonic effects with a high electron-hole binding energy within the Bethe-Salpeter equation. Band structures of graphdiyne and halogenated graphdiyne show that these nanostructures are semiconductors with a direct band gap of ~0.5 eV at the center of Brillouin zone. Halogenation of graphdiyne can effectively modulate the band gap. The second-order elastic constants and other related quantities such as the Young's modulus and Poisson's ratio have also been calculated in the present work.