Bending effects and optical properties of WSe2 nanoribbons of topological phase

TL;DR

This study investigates the topological edge states and optical properties of 1T' phase WSe2 nanoribbons, revealing their robustness under bending and potential for quantum electronic applications.

Contribution

It provides first-principles analysis of how bending affects topological and optical properties of WSe2 nanoribbons, highlighting their tunability for quantum technologies.

Findings

Topological edge states persist under small and medium bending.

Large bending causes band splitting and topological switch-off.

Bending tunes optical absorption and exciton brightness.

Abstract

A WSe2 monolayer of 1T' phase is a large band gap quantum spin Hall insulator, supporting dissipationless charge and spin transports through the topologically protected edge states. In this work, we explore the nanoribbon forms of 1T' phase WSe2 by first-principles density functional calculations and the many-body perturbation GW and Bethe-Salpeter equation method. We found that the 1T' WSe2 nanoribbon can show topological edge states with a ribbon width of ~4-6 nm. Those edge bands show crossing through the Fermi level an odd number of times, with one kind of spin-polarization connecting the valence band continuum and conduction band continuum. The topological features of the edge bands hold even under small and medium bending in the nanoribbon, while large bending induces large band splitting, resulting in a topological switch-off in the edge bands. The semiconducting 1T' WSe2 nanoribbon shows a large tunability with bending in optical absorption spectra and exciton states. The lowest-energy exciton is changed from optically dark in the flat nanoribbon to bright in the bent nanoribbons. These properties in the 1T' WSe2 nanoribbons suggest potential applications in controllable quantum electronics and exciton-based quantum information processes.