Tunable band gaps and optical absorption properties of bent MoS$_2$ nanoribbons

TL;DR

This study investigates how bending affects the electronic and optical properties of MoS₂ nanoribbons, revealing tunable band gaps and excitonic features that are promising for optoelectronic applications.

Contribution

It provides a detailed theoretical analysis of the effects of bending on MoS₂ nanoribbons' band structure and optical properties using advanced computational methods.

Findings

Band gaps show non-monotonic behavior with bending.

Edge gap splitting oscillates with ribbon width due to quantum confinement.

Optical absorption and exciton binding energies decrease with increased bending.

Abstract

The large tunability of band gaps and optical absorptions of armchair MoS$_2$ nanoribbons of different widths under bending is studied using density functional theory and many-body perturbation GW and Bethe-Salpeter equation approaches. We find that there are two critical bending curvatures, and the non-edge and edge band gaps generally show a non-monotonic trend with bending. The non-degenerate edge gap splits show an oscillating feature with ribbon width n, with a period delta_n=3, due to quantum confinement effects. The complex strain patterns on the bent nanoribbons control the varying features of band structures and band gaps that result in varying exciton formations and optical properties. The binding energy and the spin singlet-triplet split of the exciton forming the lowest absorption peak generally decrease with bending curvatures. The large tunability of optical properties of bent MoS$_2$ nanoribbons is promising and will find applications in tunable optoelectronic nanodevices.