title: Efficient green phosphorescent organic light-emitting diodes depending on concentration of lithium quinolate in electron transport layer.
abstract: Systematic studies on carrier injection and transport are very important for achieving high efficiency in OLEDs. We demonstrate excellent green phosphorescent organic light-emitting diodes (OLED) with lithium quinolate (Liq) doped in 1,3,5-tris(N-phenylbenzimidazole-2-yl) benzene (TPBi) as the electron transport layer (ETL). The doping concentration of Liq was varied from 0% to 10%. The optimized green phosphorescent OLED with 5% Liq in the ETL showed the best efficiencies, which were maximum luminous efficiency, power efficiency, and quantum efficiency of 65.76 cd/A, 57.39 Im/W, and 20.03%, respectively. Moreover, high triplet energy states of TCTA and TPBi as a triplet exciton-blocking layer (TEBL) played a role in efficient exciton confinement.
authors.affiliation: Department of Information Display, Hongik University, Seoul 121-791, Korea.
authors.forename: Bo Young
authors.initials: BY
authors.lastname: Kim
authors.forename: Seok Jae
authors.initials: SJ
authors.lastname: Lee
authors.forename: Ja Ryong
authors.initials: JR
authors.lastname: Koo
authors.forename: Song Eun
authors.initials: SE
authors.lastname: Lee
authors.forename: Kum Hee
authors.initials: KH
authors.lastname: Lee
authors.forename: Ju An
authors.initials: JA
authors.lastname: Yoon
authors.forename: Woo Young
authors.initials: WY
authors.lastname: Kim
authors.forename: Seung Soo
authors.initials: SS
authors.lastname: Yoon
authors.forename: Young Kwan
authors.initials: YK
authors.lastname: Kim