title: Highly efficient blue- and white-organic light emitting diodes base on triple-emitting layer.
abstract: We have demonstrated highly efficient blue phosphorescent organic light-emitting diodes (PHOLEDs) using iridium (III) bis[(4,6-di-fluoropheny)-pyridinato-N,C2] picolinate (Flrpic) doped in three kinds of host materials, such as 9-(4-(triphenylsilyl)phenyl)-9H-carbazole (SPC), N,N'-dicarbazolyl-3,5-benzene (mCP), and 2,2',2"-(1,3,5-benzenetriyl)tris-[1-phenyl-1H-benzimidazole] (TPBi) as triple-emitting layer (T-EML). The properties of device with T-EML using the stepwise structure was found to be superior to the other blue PHOLEDs and exhibited a maximum luminous efficiency of 23.02 cd/A, a maximum external quantum efficiency of 11.09%, and a maximum power efficiency of 14.89 lm/W, respectively. An optimal blue device has improving charge balance and triplet excitons confinement within emitting layers (EMLs) each. Additionally, we also fabricated white PHOLED using a phosphorescent red dopant, bis(2-phenylquinolinato)-acetylacetonate iridium III (Ir(pq)2acac) doped in mCP and TPBi between blue EMLs. The properties of white PHOLED showed a maximum luminous efficiency and a maximum external quantum efficiency of 33.03 cd/A and 16.95%, respectively. It also showed the white emission with CIEx,y coordinates of (x = 0.36, y = 0.39) at 10 V.
authors.affiliation: Department of Information Display, Hongik University, Seoul 121-791, Korea.
authors.forename: Hyun Su
authors.initials: HS
authors.lastname: Shin
authors.forename: Seok Jae
authors.initials: SJ
authors.lastname: Lee
authors.forename: Ho Won
authors.initials: HW
authors.lastname: Lee
authors.forename: Dong Hyung
authors.initials: DH
authors.lastname: Lee
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