Tunable band gaps and optical absorption properties of bent MoS2 nanoribbons

Hong Tang,Santosh Neupane,Niraj K Nepal,Bimal Neupane,Adrienn Ruzsinszky,Shiqi Ruan

doi:10.1038/s41598-022-06741-3

Abstract

The large tunability of band gaps and optical absorptions of armchair MoS2 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 three 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 MoS2 nanoribbons is promising and will find applications in tunable optoelectronic nanodevices.

Highlights

The large tunability of band gaps and optical absorptions of armchair MoS2 nanoribbons of different widths under bending is studied using density functional theory and many-body perturbation GW and Bethe–Salpeter equation approaches
Since edge band positions in band structures and edge band gaps are important for the optical absorption of nanoribbons, it is appealing to show how the edge bands will evolve with bending for varied widths of nanoribbons and how this will modify the optical properties
The band structures of nanoribbons show a large tunability with bending

Summary

Introduction

The large tunability of band gaps and optical absorptions of armchair MoS2 nanoribbons of different widths under bending is studied using density functional theory and many-body perturbation GW and Bethe–Salpeter equation approaches. 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. They are light weight and flexible, yet with a relatively high mechanical strength They can be tailored into different shapes, intercalated by other atoms and molecules, strained in-plane, bent out-of-plane, rolled up into scrolls, wrinkled or folded in the 2D plane, and conformed onto a nanoscale-patterned s ubstrate[7], achieving varied, controllable properties. We use the GW + BSE approach to calculate the optical absorption spectra and reveal a large tunability of optical absorption by bending nanoribbons

Methods

Results

Conclusion