Hybridized quadrupole-dipole exciton effects in $Cu_2O$ - Organic Heterostructure

TL;DR

This paper explores the resonant hybridization of quadrupole Wannier-Mott excitons in Cu2O with Frenkel excitons in an organic layer, demonstrating tunable strong coupling with potential applications in optoelectronics.

Contribution

It introduces a novel hybridization mechanism between quadrupole and dipole excitons in a heterostructure, utilizing 'solid state solvation' for dynamic resonance tuning.

Findings

Successful demonstration of resonant hybridization in heterostructure

Tunable coupling via 'solid state solvation' mechanism

Pronounced minimum in hybrid dispersion for potential applications

Abstract

In the present work we discuss resonant hybridization of the $1S$ quadrupole Wannier-Mott exciton (WE) in a $Cu_2O$ quantum well with the Frenkel (FE) dipole exciton in an adjacent layer of organic DCM2:CA:PA. The coupling between excitons is due to interaction between the gradient of electric field induced by DCM2 Frenkel exciton and the quadrupole moment of the $1S$ transition in the cuprous oxide. The specific choice of the organic allows us to use the mechanism of 'solid state solvation' to dynamically tune the WE and FE into resonance during time $\approx 3.3 \: ns$ (comparable with the big life time of the WE) of the 'slow' phase of the solvation. The quadrupole-dipole hybrid utilizes the big oscillator strength of the FE along with the big lifetime of the quadrupole exciton, unlike dipole-dipole hybrid exciton which utilizes big oscillator strength of the FE and big radius of the dipole allowed WE. Due to strong spatial dispersion and big mass of the quadrupole WE the hybridization is not masked by the kinetic energy or the radiative broadening. The lower branch of the hybrid dispersion exhibits a pronounced minimum and may be used in applications. Also we investigate and report noticeable change in the coupling due to a induced 'Stark effect' from the strong local electric field of the FE. We investigated the fine energy structure of the quantum well confined ortho and para excitons in cuprous oxide.