Dresden 2017 – wissenschaftliches Programm
CPP 50.13: Poster
Mittwoch, 22. März 2017, 18:30–21:00, P3
controlling excitons in exciplex host systems for efficient white OLEDs — •Yuan Liu, Simone Lenk, Karl Leo, and Sebastian Reineke — Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, George-Bähr-Straße 1, 01069 Dresden, Germany
White organic light-emitting diodes (WOLEDs) are highly attractive for flexible displays and lighting panels due to their ultrathin form factor, low cost, good color quality, and high power efficiency. Here, an exciplex system consisting of mCP and B3PYMPM is demonstrated to achieve high efficiency blue and white OLEDs. Employing Iridium(III) bis[(4,6-difluorophenyl)pyridinato-N, C2*] picolinate (FIrpic) as emitter, an external quantum efficiency (EQE) of 19.1% is realized by optimizing the hole and electron transporting layer. Triplet-triplet annihilation and triplet-polaron quenching models are utilized to understand the efficiency roll-off of the devices. Based on optimized blue OLEDs, an efficient WOLED with maximum 19.5% EQE (50.6 lm/W) has been realized by carefully controlling exciton generation and transfer processes. At the practical brightness of 1000 cd/m2, it still keeps 18.8% EQE (42.7 lm/W). Adopting a glass half sphere as a light out-coupling technology, the luminous efficacy of the WOLED reaches a maximum of 84.9 lm/W with Commission International de L*Eclairage coordinates of (0.452, 0.457) and a color rendering index of 81. Further, the influence factors of color stability and efficiency roll-off in exciplex-based WOLEDs are investigated in detail.