Electronic properties and quantum confinement in Bi2S3 ribbon-like nanostructures

In this work we study the morphology and electronic properties of Bi2S3 nanostructures by means of atomistic simulations. We focus on elongated nanoribbons that are the building blocks of the corresponding crystal structures, and we study saturated and unsaturated nanocrystals of finite size in comparison with one-dimensional infinite ones. By means of (time-dependent) density functional theory calculations we provide evidence that the optical gap can be tuned through quantum confinement with sizable effects for ribbons smaller than three nanometers. By a comparison with Sb2S3, we conclude that Bi2S3 nanostructures have similar tunability of the bandgap and a better tendency of passivating defects at the (010) surfaces through local reconstructions.