  Two-dimensional (2D) transition metal dichalcogenide (TMD) materials have
versatile electronic and optical properties. TMD nanoribbons show interesting
properties due to reduced dimensionality, quantum confinement, and edge states.
Tang et al. showed that the edge bands evolved with bending can tune the
optical properties for various widths of TMD nanoribbons. Defects are commonly
present in 2D TMD materials, and can dramatically change the material
properties. In this following work, we investigate the interaction between the
edge and the defect states in WS2 nanoribbons with line defects under different
bending conditions, using density functional theory (DFT). We reveal
interesting semiconducting-to-metallic phase transitions, suggesting potential
applications in nano-electronics or molecular electronics. We also calculate
the optical absorption of the nanoribbons with different defect positions with
the many-body GW-BSE (Bethe-Salpeter equation) approach, revealing a tunable
optical spectrum and diverse exciton states in the defected TMD nanoribbons.
