title: Phosphorescent dye-based supramolecules for high-efficiency organic light-emitting diodes.
abstract: Organic light-emitting diodes (OLEDs) are among the most promising organic semiconductor devices. The recently reported external quantum efficiencies (EQEs) of 29-30% for green and blue phosphorescent OLEDs are considered to be near the limit for isotropically oriented iridium complexes. The preferred orientation of transition dipole moments has not been thoroughly considered for phosphorescent OLEDs because of the lack of an apparent driving force for a molecular arrangement in all but a few cases, even though horizontally oriented transition dipoles can result in efficiencies of over 30%. Here we use quantum chemical calculations to show that the preferred orientation of the transition dipole moments of heteroleptic iridium complexes (HICs) in OLEDs originates from the preferred direction of the HIC triplet transition dipole moments and the strong supramolecular arrangement within the co-host environment. We also demonstrate an unprecedentedly high EQE of 35.6% when using HICs with phosphorescent transition dipole moments oriented in the horizontal direction.
authors.affiliation: WCU Hybrid Materials Program, Department of Materials Science and Engineering and the Center for Organic Light Emitting Diodes, Seoul National University, Seoul 151-742, South Korea.
authors.forename: Kwon-Hyeon
authors.initials: KH
authors.lastname: Kim
authors.affiliation: WCU Hybrid Materials Program, Department of Materials Science and Engineering and the Center for Organic Light Emitting Diodes, Seoul National University, Seoul 151-742, South Korea.
authors.forename: Sunghun
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Materials Science and Engineering and the Center for Organic Light Emitting Diodes, Seoul National University, Seoul 151-742, South Korea.
authors.forename: Chang-Ki
authors.initials: CK
authors.lastname: Moon
authors.affiliation: Department of Materials Science and Engineering and the Center for Organic Light Emitting Diodes, Seoul National University, Seoul 151-742, South Korea.
authors.forename: Sei-Yong
authors.initials: SY
authors.lastname: Kim
authors.affiliation: Department of Materials Science and Engineering and the Center for Organic Light Emitting Diodes, Seoul National University, Seoul 151-742, South Korea.
authors.forename: Young-Seo
authors.initials: YS
authors.lastname: Park
authors.affiliation: WCU Hybrid Materials Program, Department of Materials Science and Engineering and the Center for Organic Light Emitting Diodes, Seoul National University, Seoul 151-742, South Korea.
authors.forename: Jeong-Hwan
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Catalyst Research, Samsung Total Petrochemicals, Daesan-eup, Chungnam 356-711, South Korea.
authors.forename: Jin
authors.initials: J
authors.lastname: Woo Lee
authors.affiliation: Department of Chemical and Biological Engineering, Korea University, Anam-dong, Seongbuk-gu, Seoul 136-713, South Korea.
authors.forename: June
authors.initials: J
authors.lastname: Huh
authors.affiliation: Department of Advanced Materials Engineering for Information and Electronics, Kyung Hee University, Yongin-si, Gyeonggi-do 446-701, South Korea.
authors.forename: Youngmin
authors.initials: Y
authors.lastname: You
authors.affiliation: 1] WCU Hybrid Materials Program, Department of Materials Science and Engineering and the Center for Organic Light Emitting Diodes, Seoul National University, Seoul 151-742, South Korea [2] Department of Materials Science and Engineering and the Center for Organic Light Emitting Diodes, Seoul National University, Seoul 151-742, South Korea.
authors.forename: Jang-Joo
authors.initials: JJ
authors.lastname: Kim