Role of Synthesis for Oxygen Defect Incorporation in Crystalline Rubrene

Using photoluminescence characteristics at room temperature we analyze incorporation of an oxygen-related defect, most likely rubrene- peroxide, which produces an acceptor state in crystalline rubrene. Incorporation of rubrene-peroxide molecules can occur during the crystal growth as well as a result of the post-growth oxidation, which depends on the presence of structural disorder.