Department of Chemistry
Reduced efficiency roll-off in highly efficient and color-stable hybrid WOLEDs: The Influence of triplet transfer and charge-transport behavior on enhancing device performance
By wisely utilizing combinations of exciton-managed orange-phosphorescence/sky blue-fluorescence, we report on high-efficiency white organic light-emitting diodes (WOLEDs) with high color-stability together with reduced efficiency roll-off. Two WOLEDs with the peak current efficiencies of 34.5 and 42.5 cd A-1 which slightly shift to 34.2 and 40.0 cd A-1 at 1000 cd m-2 are demonstrated. Systematic investigations focused on the effects of hole-injection buffer layer, thickness of emitting-layer (EML) and the stepwise-doping profile of orange phosphorescent EML on the device performance have been performed. It is evidently shown that careful management of the triplet/singlet excitons and charge-carriers is key to realizing such high performance of the devices. The results will beyond doubt be helpful to the design of both material and device structure for high-performance WOLEDs and next-generation solid-state lighting sources. © 2009 Elsevier B.V. All rights reserved.
Carbazole, Iridium complexes, Organic light-emitting diodes, Triplet emission, White light
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Link to Publisher's Edition
Wang, Qi, Cheuk-Lam Ho, Yongbiao Zhao, Dongge Ma, Wai-Yeung Wong, and Lixiang Wang. "Reduced efficiency roll-off in highly efficient and color-stable hybrid WOLEDs: The Influence of triplet transfer and charge-transport behavior on enhancing device performance." Organic Elecronics 11.2 (2010): 238-246.