title: Highly efficient and stable white organic light emitting diode base on double recombination zones of phosphorescent blue/orange emitters.
abstract: We demonstrated efficient and stable white phosphorescent organic light-emitting diodes (OLEDs) with double-emitting layers (D-EMLs), which were comprised of two emissive layers with a hole transport-type host of N,N'-dicarbazolyl-3,5-benzene (mCP) and a electron transport-type host of 2,2',2"-(1,3,5-benzenetryl)tris(1-phenyl)-1H-benzimidazol (TPBi) with blue/orange emitters, respectively. We fabricated two type white devices with single emitting layer (S-EML) and D-EML of orange emitter, maintaining double recombination zone of blue emitter. In addition, the device architecture was developed to confine excitons inside the D-EMLs and to manage triplet excitons by controlling the charge injection. As a result, light-emitting performances of white OLED with D-EMLs were improved and showed the steady CIE coordinates compared to that with S-EML of orange emitter, which demonstrated the maximum luminous efficiency and external quantum efficiency were 21.38 cd/A and 11.09%. It also showed the stable white emission with CIE(x,y) coordinates from (x = 0.36, y = 0.37) at 6 V to (x = 0.33, y = 0.38) at 12 V.
authors: Department of Information Display, Hongik University, Seoul 121-791, Korea.
authors: Seok Jae
authors: SJ
authors: Lee
authors: Ja Ryong
authors: JR
authors: Koo
authors: Dong Hwan
authors: DH
authors: Lim
authors: Hye Rim
authors: HR
authors: Park
authors: Young Kwan
authors: YK
authors: Kim
authors: Yunkyoung
authors: Y
authors: Ha