Hybridized quadrupole-dipole exciton effects in a Cu 2 O -organic heterostructure

In the present work, we discuss resonant hybridization of the $1S$ quadrupole Wannier-Mott exciton (WE) in a ${\mathrm{Cu}}_{2}\mathrm{O}$ quantum well with the Frenkel 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 the DCM2 Frenkel exciton (FE) 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'' [C. Madigan and V. Bulovic, Phys. Rev. Lett. 91, 247403 (2003)] to dynamically tune the WE and FE into resonance for $\ensuremath{\approx}3.3\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$ (comparable with the big lifetime 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 the big oscillator strength of the FE and big radius of the dipole allowed WE. Due to the 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 an 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.