Optical Absorption of Armchair MoS2 Nanoribbons: Enhanced Correlation Effects in the Reduced Dimension

Abstract

We carry out first-principles calculations of the quasi-particle band structure and optical absorption spectra of H-passivated armchair MoS<inf>2</inf> nanoribbons (AMoS<inf>2</inf>NRs) by employing the approach combining the Green&apos;s function perturbation theory (GW) and the Bethe-Salpeter equation (BSE), i.e., GW+BSE. Optical absorption spectra of AMoS<inf>2</inf>NRs show the exciton multibands (their binding energies are close to or less than 1 eV) which are much stronger than a single layer of MoS<inf>2</inf>. However, they are absent in the spectra by the approach of GW and the random phase approximation (RPA), i.e., GW+RPA. This signifies that the excitonic correlation effects are strongly enhanced in the reduced dimensional structure of MoS<inf>2</inf>. We also calculate the exciton wave functions for the few lowest energy excitons, which are found to have non-Frenkel character. © 2015 American Chemical Society.