Valley-Selective Response of Nanoantennas Coupled to 2D Transition Metal Dichalcogenides

TL;DR

This paper reviews how nanoantennas coupled with monolayer transition metal dichalcogenides enable valley-selective emission and exciton control, addressing challenges in valley pseudospin applications at room temperature.

Contribution

It summarizes recent advances in nanostructure-mediated valley-selective emission and exciton sorting in 1L-TMDCs, highlighting the role of nanoantennas in overcoming valley pseudospin limitations.

Findings

Nanoantennas enable directional valley-selective emission.

Coupling enhances valley pseudospin stability at room temperature.

Recent nanostructures improve exciton control in 2D materials.

Abstract

Monolayer (1L) transition metal dichalcogenides (TMDCs) are attractive materials for several optoelectronic applications because of their strong excitonic resonances and valley-selective response. Valley excitons in 1L-TMDCs are formed at opposite points of the Brillouin zone boundary, giving rise to a valley degree of freedom that can be treated as a pseudospin and may be used as a platform for information transport and processing. However, short valley depolarization times and relatively short exciton lifetimes at room temperature prevent using valley pseudospin in on-chip integrated valley devices. Recently it has been demonstrated how coupling these materials to optical nanoantennas and metasurfaces can overcome this obstacle. Here, we review the state-of-the-art advances in valley-selective directional emission and exciton sorting in 1L-TMDC mediated by nanostructures and nanoantennas. We briefly discuss the optical properties of 1L-TMDCs paying special attention to their photoluminescence/absorption spectra, dynamics of valley depolarization and valley Hall effect. Then, we review recent works on nanostructures for valley-selective directional emission from 1L-TMDCs.