Abstract
High efficiency all fluorescent white organic light-emitting diodes (WOLEDs) based on yellow fluorescent guest doped blue exciplex host as the emitting layer (EML) are fabricated by inserting a thin hole-transporting layer (HTL) in EML. It is found that the thin HTL forms an additional interface exciplex in EML, as a result, the efficiency and efficiency roll-off at high luminance are greatly improved by the efficient exciton control via the interface exciplex. The resulting WOLEDs show the maximum current efficiency (CE), power efficiency (PE) and external quantum efficiency (EQE) of 32.6 cd/A, 35.9 lm/W and 10.1%, respectively, and 25.6 cd/A, 16.1 lm/W and 8.1% at 1000 cd/m(2) luminance, indicating the effectiveness of this interface exciplex structure to achieve remarkable efficiency all fluorescent WOLEDs.