Short Excited-State Lifetimes Enable Photo-Oxidatively Stable Rubrene Derivatives

A series
of rubrene derivatives were synthesized and the influence
of the side group in enhancing photo-oxidative stability was evaluated.
Photo-oxidation half-lives were determined via UV–vis absorption
spectroscopy, which revealed thiophene containing derivatives to be
the most stable species. The electron affinity of the compounds did
not correlate with stability as previously reported in literature.
Our work shows that shorter excited-state lifetimes result in increased
photo-oxidative stability in these rubrene derivatives. These results
confirm that faster relaxation kinetics out-compete the formation
of reactive oxygen species that ultimately degrade linear oligoacenes.
This report highlights the importance of using molecular design to
tune excited-state lifetimes in order to generate more stable oligoacenes.