Plasmon‐Mediated Hybridization of Wannier–Mott and Frenkel Excitons in a Monolayer WS₂–J‐Aggregate Hybrid System

A tunable plasmonic platform that allows room‐temperature hybridization of dissimilar excitons, namely of Wannier–Mott excitons in monolayer (1L) WS 2 and Frenkel excitons in molecular J‐aggregates via simultaneous strong coupling (SC) to surface plasmon polaritons, is presented. It is based on a simple layered design consisting of a thin planar silver film and a dielectric spacer on which monolayer and the aggregates are assembled. SC is revealed by angle‐dependent spectroscopic ellipsometry measurements in total internal reflection geometry by the observation of double Rabi splitting at the two excitonic resonances. The exciton‐exciton‐plasmon system is analyzed with the coupled oscillator model, and modulation of polariton character and dynamics by the number of molecules participating in the coupling is demonstrated. Furthermore, a route is proposed to remotely control the mode splitting at the Frenkel excitonic resonance via electrostatic gating of the 1L‐WS 2 and to switch the molecule–plasmon interaction between the weak and SC regime.