Harvesting triplet excitons from fluorescent blue emitters for high-efficiency white organic light emitting diodes

摘要

We present a novel organic light emitting device concept for white light generation with the potential for 100% internal quantum efficiency, which employs fluorescent blue and phosphorescent green and orange emitters. Due to its high triplet energy, the intrinsically non-radiative triplet excitons of the fluorescent blue emitter can still be harvested for light emission by letting them diffuse to the phosphor-containing emission layers. Thus, all electrically generated excitons can be used for light emission without the need for phosphorescent blue emitters, which suffer from stability problems. We demonstrate the high potential of this concept in a device achieving 57.6 lmW-1 total external power efficiency at 100 cd m-2 (20.3% external quantum efficiency) and 37.5 lmW-1 (14.4%) at an illumination relevant brightness of 1,000 cd m-2, and a high color rendering index of 86.