Monolayer MoSe2: A candidate for room temperature polaritonics

TL;DR

This paper explores the potential of monolayer MoSe2 for room temperature polaritonics by analyzing exciton behavior and coupling with microcavities, indicating feasible polariton formation in certain photonic structures.

Contribution

It provides the first detailed analysis of temperature effects on MoSe2 excitons and demonstrates the possibility of achieving strong exciton-photon coupling at ambient conditions.

Findings

Strong phonon-induced broadening of excitons with temperature

Reduction of oscillator strength at higher temperatures

Feasibility of exciton-polariton formation in specific photonic architectures

Abstract

Monolayered MoSe2 is a promising new material to investigate advanced light-matter coupling as it hosts stable and robust excitons with comparably narrow optical resonances. In this work, we investigate the evolution of the lowest lying excitonic transition, the so-called A-valley exciton, with temperature. We find a strong, phonon-induced temperature broadening of the resonance, and more importantly, a reduction of the oscillator strength for increased temperatures. Based on these experimentally extracted, temperature dependent parameters, we apply a coupled oscillator model to elucidate the possibility to observe the strong coupling regime between the A-exciton and a microcavity resonance in three prototypical photonic architectures with varying mode volumes. We find that the formation of exciton-polaritons up to ambient conditions in short, monolithic dielectric and Tamm-based structures seems feasible. In contrast, a temperature-induced transition into the weak coupling regime can be expected for structures with extended effective cavity length. Based on these findings, we calculate and draw the phase diagram of polariton Bosonic condensation in a MoSe2 cavity.