High efficiency hybrid white OLEDs

Abstract

White organic light-emitting diodes (WOLEDs) are attracting significant attention due to its unique merits of fabrication of large-scale for solid-state lighting sources, full-color displays and backlights for liquid-crystal displays [1]. The phosphorescent WOLEDs showed outstanding efficiency since all electrically generated singlet and triplet excitons can be harvested by phosphorescent emitters [2]. However, the development of phosphorescent WOLEDs is severely limited by the absence of efficient deep-blue phosphorescent emitters with an operational lifetime suitable for commercial applications [3]. Hybrid WOLEDs which combine a stable blue fluorophor with red and green (or yellow) phosphors have been reported to show much more stable operation with respect to all-phosphorescent WOLEDs by avoiding the relatively unstable blue phosphor, but not affect the harvesting of both triplet and singlet excitons for efficient white emission [4]. Thus, hybrid WOLEDs with three primary colors are more in line with the requirements of lighting application.