Stability to photo-oxidation of rubrene and fluorine-substituted rubrene

Rubrene, among organic semiconductors, displays very high charge carrier mobility in the solid state and this is why it has become a very promising material for various device applications. Unfortunately, rubrene also exhibits a rather low stability, affecting device lifetime, because it is very prone to photo-oxidation. In order to limit this problem, a new substituted-rubrene was synthesized, which should be more stable, still having a good transport behaviour in the solid state. In this paper, we show how molecule degradation by reaction with oxygen under light makes the solutions and thin films become colorless, as observed by monitoring in time the evolution of absorbance. We found that the degradation of rubrene in both solutions and thin films is faster than that of the fluorine-substituted molecule. These results demonstrate that the introduction of fluorine can be a way to enhance the stability of rubrene to photo-oxidation.