Dark-Exciton-Mediated Fano Resonance from a Single Gold Nanostructure Deposited on Monolayer WS2 at Room Temperature

TL;DR

This study demonstrates that dark excitons in monolayer WS2 can strongly influence Fano resonances in hybrid gold nanostructure systems, enabling potential applications in nanophotonic sensors at room temperature.

Contribution

It reveals the interaction between dark excitons and surface plasmons in a hybrid system, leading to narrow Fano resonances at room temperature, which was not previously demonstrated.

Findings

Narrow Fano resonance observed in hybrid system surrounded by water.

Spectral linewidth narrowing due to plasmon-enhanced dark exciton decay.

Dark excitons significantly modify Fano resonances in plasmon-exciton systems.

Abstract

Strong spatial confinement and highly reduced dielectric screening provide monolayer transition metal dichalcogenides (TMDCs) with strong many-body effects, thereby possessing optically forbidden excitonic states (i.e., dark excitons) at room temperature. Herein, we explore the interaction of surface plasmons with dark excitons in hybrid systems consisting of stacked gold nanotriangles (AuNTs) and monolayer WS2. We observe a narrow Fano resonance when the hybrid system is surrounded by water, and we attribute the narrowing of the spectral Fano linewidth to the plasmon-enhanced decay of dark K-K excitons. Our results reveal that dark excitons in monolayer WS2 can strongly modify Fano resonances in hybrid plasmon-exciton systems and can be harnessed for novel optical sensors and active nanophotonic devices.