Photostabilization of J-aggregate cyanine dyes for exciton-polariton based devices

Abstract

Organic molecules are becoming a commonly used material in strongly coupled systems as they possess large exciton binding energies and huge oscillator strengths that have allowed for the creation of room temperature polariton condensates, superfluids, and other exotic phenomena. Using J-aggregates, the aggregated form of cyanine organic dyes, we have previously fabricated light-emitting devices that demonstrated the first ever electrically pumped polariton emission, as well as critically coupled resonators with record high effective absorption constants. Although there are many promising applications for organic exciton-polariton devices, state-of-the- art devices suffer from rapid photodegradation at higher photon densities, which presently limits their eventual implementation into a viable technology. To achieve stable devices, we need to isolate the causes of photodegradation. Specifically, we studied the photoluminescence stability of J-aggregate thin films under different atmospheric conditions. Our results indicated that J-aggregates maintain both better emission and stability in high humidity environments in comparison to oxygen-rich atmospheres. Furthermore, we show an order of magnitude improvement in the photostability via encapsulation of the film with a hygroscopic sugar encapsulant. These results are highly promising and suggest future pathways for the realization of functional and stable polariton-based devices which we will explore in this thesis.