Efficient Föster energy transfer : from phosphorescent organic molecules to J-aggregate thin film

Abstract

This thesis demonstrates the first ever use of Forster resonance energy transfer (FRET) to increase the quantum efficiency of a electrically pumped J-aggregate light emitting device (JLED). J-aggregate thin films are highly absorptive films that have potential applications in a new class of optoelectronic devices, known as polaritonic devices. These devices, which utilize strong coupling between light and matter, include room temperature low power optical switches and low threshold lasers. Recent work has shown that a J-aggregate strong-coupling device can be powered not just optically but also electrically. However, since J aggregates are engineered for their optical and not electrical properties, exciting them electrically is very inefficient. JLED efficiency can be improved by first exciting phosphors that readily form excitons and then employing FRET to excite the J aggregates. Attaining high efficiency can make electrical pumping a viable option to power polaritonic devices.