Study of the degradation of nanometer sized PPV polymer thin films enclosed in organic light emitting devices using spectroscopic ellipsometry

摘要

In this work spectroscopic ellipsometry was used to study the optical behaviour of thin yellow luminescent PPV layers, contained in complete OLED devices. Furthermore, the degradation depending changes of the optical absorption in these layers were examined.A bandgap typical absorption peak of the PPV-layer is detected, which clearly drops with ongoing degradation.Based on these measurements, the outcome of an optical absorption spectroscopy at an isolated PPV-layer with arbitrary thickness could be accomplished.Out of the simulation, it was possible to quantify the ratio Q between absorbed photons to impinged ones. This ratio is highly depending on the amount of non degraded molecules in the layer itself.