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

► Rubrene and substituted-rubrene molecules degradation by reaction with oxygen under light makes the solutions and thin films become colorless. ► The decrease of absorption intensity in the visible range and the rise of a band at the higher energy identify photo-oxidation. ► Fluorine atoms as substituted of hydrogen atoms in rubrene enhance the stability of the molecule to photo-oxidation.