title: Oxygen-related band gap state in single crystal rubrene.
abstract: A molecular exciton signature is established and investigated under different ambient conditions in rubrene single crystals. An oxygen-related band gap state is found to form in the ambient atmosphere. This state acts as an acceptor center and assists in the fast dissociation of excitons, resulting in a higher dark and photoconductivity of oxidized rubrene. The band gap state produces a well-defined photoluminescence band at an energy 0.25 eV below the energy of the 0-0 molecular exciton transition. Two-photon excitation spectroscopy shows that the states are concentrated near the surface of naturally oxidized rubrene.
authors.affiliation: Bell Labs, Lucent Technologies, Murray Hill, NJ 07974, USA.
authors.forename: Oleg
authors.initials: O
authors.lastname: Mitrofanov
authors.forename: David V
authors.initials: DV
authors.lastname: Lang
authors.forename: Christian
authors.initials: C
authors.lastname: Kloc
authors.forename: J Magnus
authors.initials: JM
authors.lastname: Wikberg
authors.forename: Theo
authors.initials: T
authors.lastname: Siegrist
authors.forename: Woo-Young
authors.initials: WY
authors.lastname: So
authors.forename: M A
authors.initials: MA
authors.lastname: Sergent
authors.forename: Arthur P
authors.initials: AP
authors.lastname: Ramirez