title: New bipolar host materials for realizing blue phosphorescent organic light-emitting diodes with high efficiency at 1000 cd/m2.
abstract: New host molecules such as 9-(6-(9H-carbazol-9-yl)pyridin-3-yl)-6-(9H-carbazol-9-yl)-9H-pyrido[2,3-b]indole (pPCB2CZ) and 9-(6-(9H-carbazol-9-yl)pyridin-2-yl)-6-(9H-carbazol-9-yl)-9H-pyrido[2,3-b]indole (mPCB2CZ) were designed and synthesized for blue phosphorescent organic light-emitting diodes (PhOLEDs). The glass transition temperatures of two host molecules were measured higher than 120 °C, and the identical triplet energies were determined to be 2.92 eV for both molecules. The bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium(III) (FIrpic)-doped mPCB2CZ-based PhOLED exhibited practically useful driving voltage of 4.8 V in a simple organic three layer device configuration which has a smaller number of interfaces in conventional multilayer PhOLEDs. Also, the high quantum efficiency of 23.7% is reported at the practically useful brightness value of 1000 cd/m2.
authors.affiliation: Department of Chemistry, Research Institute for Natural Sciences, Korea University , 5 Anam-dong, Sungbuk-Gu, Seoul 136-701, Republic of Korea.
authors.forename: Min Ju
authors.initials: MJ
authors.lastname: Cho
authors.forename: Sun Jae
authors.initials: SJ
authors.lastname: Kim
authors.forename: Seung Hee
authors.initials: SH
authors.lastname: Yoon
authors.forename: Jicheol
authors.initials: J
authors.lastname: Shin
authors.forename: Tae Ryang
authors.initials: TR
authors.lastname: Hong
authors.forename: Hyung Jong
authors.initials: HJ
authors.lastname: Kim
authors.forename: Young Hoon
authors.initials: YH
authors.lastname: Son
authors.forename: Ju Sik
authors.initials: JS
authors.lastname: Kang
authors.forename: Hyun Ah
authors.initials: HA
authors.lastname: Um
authors.forename: Tae Wan
authors.initials: TW
authors.lastname: Lee
authors.forename: Jong-Kwan
authors.initials: JK
authors.lastname: Bin
authors.forename: Bang Sook
authors.initials: BS
authors.lastname: Lee
authors.forename: Joong Hwan
authors.initials: JH
authors.lastname: Yang
authors.forename: Gee Sung
authors.initials: GS
authors.lastname: Chae
authors.forename: Jang Hyuk
authors.initials: JH
authors.lastname: Kwon
authors.forename: Dong Hoon
authors.initials: DH
authors.lastname: Choi
keywords: bipolar host; carboline; organic light emitting diode; phosphorescence; quantum efficiency