Twist-angle engineering of excitonic quantum interference and optical nonlinearities in stacked 2D semiconductors.

ABSTRACT: Twist-engineering of the electronic structure in van-der-Waals layered materials relies predominantly on band hybridization between layers. Band-edge states in transition-metal-dichalcogenide semiconductors are localized around the metal atoms at the center of the three-atom layer and are therefore not particularly susceptible to twisting. Here, we report that high-lying excitons in bilayer WSe₂ can be tuned over 235 meV by twisting, with a twist-angle susceptibility of 8.1 meV/°, an order of magnitude larger than that of the band-edge A-exciton. This tunability arises because the electronic states associated with upper conduction bands delocalize into the chalcogenide atoms. The effect gives control over excitonic quantum interference, revealed in selective activation and deact

SUBMITTER: Lin KQ 

PROVIDER: S-EPMC7946969 | biostudies-literature | 2021 Mar

REPOSITORIES: biostudies-literature