Enhancement of ultra-thin film emission using a waveguiding active layer

TL;DR

This theoretical study demonstrates that incorporating an active waveguiding layer beneath an ultrathin luminescent film can enhance its emission by over 20 times through photon recycling, with implications for ultra-trace sensing.

Contribution

It introduces a novel approach of using an active underlying layer to significantly boost emission in ultrathin films, expanding understanding of photon recycling effects.

Findings

Active layer enhances luminescence by over 20 times

Photon recycling acts as a secondary light source

Structural parameters influence emission and radiation pattern

Abstract

We present a theoretical study on the impact of an active optical layer on the emission properties of an ultrathin luminescent film. While the study can be generalized to any material, we focus here on a simple layered medium composed of a conjugated polymers (CPs) thin film, a zinc oxide layer (ZnO) and a sapphire substrate. The study spreads throughout variable aspects including the effect of the structure parameters on the CP luminescence and radiation pattern and more specifically the influence of the absorption and emission properties of the active layer. Comparing between the passive and active layer cases, the obtained results show that an enhancement of the CP luminescence of more than 20 times can be obtained by using an optically active underlying layer. The results can be explained in terms of photon recycling where the optically active layer acts as a photon reservoir and a secondary light source for the ultra thin film. This general concept is of a special interest for ultra-trace chemosensor.