Hybridization of two fluorescent BODIPY dyes in a microcavity is achieved by coupling different exciton transitions to the same cavity mode. We characterise the luminescence of such hybrid system following non-resonant laser excitation and show that the relative population along the different polariton branches can be controlled by changing cavity detuning. This effect is used to enhance exciton energy-transfer to states along the lower polariton branch in negatively detuned cavities. We compare the efficiency of energy transfer via exciton hybridisation with that achieved by dipole-dipole coupling.

Efficient energy transfer in dispersed films of organic dyes to dark excimer sites and highly emissive J-coupled dimers.

We report on the origin of energy-shifts in organic polariton condensates. The localised nature of Frenkel excitons in molecular semiconductors precludes interparticle Coulomb exchange interactionsthe latter being the dominant mechanism for blueshifts in inorganic semiconductor microcavities that bear Wannier-Mott excitons. We examine the contribution of optically induced change of the intracavity non-linear refractive index, gain induced frequency-pulling and quenching of the Rabi splitting, as well as the role of polariton-exciton and polariton-polariton scattering in the energy-shift of the polariton mode at condensation threshold in strongly coupled molecular dye microcavities. We conclude that blueshifts in organic polariton condensates arise from the interplay of the saturation of molecular optical transitions and intermolecular energy migration. Our model predicts the commonly observed step-wise increase of both the emission energy and degree of linear polarisation at polariton condensation threshold.

Two pyrene dimers containing an -O-Si-Si-O- or -O-Si-O- linkage have been designed which exhibit ratiometric excimer/monomer emission upon fluoride anion induced Si-O bond cleavage. Incorporation of the probe into water soluble polymeric nanoparticles enhances its intracellular uptake and displays ratiometric fluorescent sensing for F(-) in living cells.