Interlayer exciton polaritons in homobilayers of transition metal dichalcogenides

TL;DR

This paper demonstrates that MoS2 homobilayer microcavities can support interlayer exciton polaritons with significant interlayer exciton contributions, tunable hybridization, and potential for advanced optoelectronic applications.

Contribution

It introduces a microscopic model showing large interlayer exciton contributions in polaritons and reveals how cavity tuning can control exciton hybridization.

Findings

Polaritons with >90% interlayer exciton contribution predicted.

Cavity tuning can 'unmix' intra- and interlayer excitons.

Effective optical energy transfer despite weak oscillator strength.

Abstract

Transition metal dichalcogenides integrated within a high-quality microcavity support well-defined exciton polaritons. While the role of intralayer excitons in 2D polaritonics is well studied, interlayer excitons have been largely ignored due to their weak oscillator strength. Using a microscopic and material-realistic Wannier-Hopfield model, we demonstrate that MoS$_2$ homobilayers in a Fabry-Perot cavity support polaritons that exhibit a large interlayer exciton contribution, while remaining visible in linear optical spectra. Interestingly, with suitable tuning of the cavity length, the hybridization between intra- and interlayer excitons can be 'unmixed' due to the interaction with photons. We predict formation of polaritons where > 90% of the total excitonic contribution is stemming from the interlayer exciton. Furthermore, we explore the conditions on the tunneling strength and exciton energy landscape to push this to even 100%. Despite the extremely weak oscillator strength of the underlying interlayer exciton, optical energy can be effectively fed into the polaritons once the critical coupling condition of balanced radiative and scattering decay channels is met. These findings have a wide relevance for fields ranging from nonlinear optoelectronic devices to Bose-Einstein condensation.