Date

Place

[P2-123]
14:00 ~ 15:30
Title:Improved Luminous Efficacy of Hybrid Tandem White OLEDs with a Li-Doped Charge Generation Layer
Hyunsu Cho, Namsung Cho, Chul Woong Joo, Jonghee Lee, Doo-Hee Cho, Jaehyun Moon, Jin-Wook Shin, Seung Koo Park, and Jeong-Ik Lee (ETRI, Korea)
Abstract: Tandem architecture is widely used to realize WOLEDs due to high efficiency, long lifetime, and color stability. In the tandem OLEDs, the suppressed voltage loss in a charge generation layer (CGL) is important for the development of low driving voltage and high luminous efficacy.1,2 In this paper, we report high luminous efficacy tandem WOLEDs with optimal CGLs. Various electron transporting materials used as a nCGL with Li doping, resulting in similar turn-on voltage. However, they influences on the electrical propertis of tandem WOLEDs, especially an operating voltage. Depending on nCGL, the operating voltage at 5mA/cm2 can be reduced by 0.8V as shown in Fig 1. With an optimization of CGL and each unit cells (fluorescent blue and phosphorescent yellowish-green) in hybrid tandem WOLEDs, we demonstrated power efficiency of 42.7lm/W and external quantum efficiency of 28.8% without any light extraction techniques. In addition, hybrid tamdem white OLEDs in this study exhibited a lifetime of over 40,000 hours at 1,000 nits. Finally, WOLEDs with light extraction techniques results will be discussed.
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