Crystallinity-modulated hollow CeO2−x nanorods as free radical scavengers for long-term photostability in organic photovoltaics

Abstract

Here we investigated the effects of CeO_2−x nanostructures as free radical scavengers on the long-term photostability of an organic photovoltaic (OPV) structure. From powder X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and N₂ adsorption experiments, it was determined that the single-crystalline hollow CeO_2−x nanorods were very effective as hydroxyl radical scavengers. This was attributed to their having more Ce³⁺ states and a wider surface area than other types of CeO₂ nanostructures. Time-dependent UV-visible absorption spectra analyses also revealed that the improved scavenging of hydroxyl radicals in the OPV device was related to the better interfacial compatibility between the organic active and ZnO layers, resulting in improved OPV photostability.