17.3: Highly Efficient Fluorescent/Phosphorescent OLED Devices Using Triplet Harvesting

We demonstrate efficient white and non-white hybrid OLED devices operating by a triplet harvesting mechanism to create light. Triplet excited states are generated in a blue fluorescent light-emitting layer (LEL) and utilized upon their diffusion to the phosphorescent LEL(s). At 1000 cd/m2 a blue/yellow hybrid OLED device shows external quantum efficiency (EQE) of 13.6%, 3.8 V, 30.1 lm/W, and excellent color characteristics suitable for display application. Performance of non-white-emitting hybrids, RGB white, and a tandem hybrid device is discussed. The triplet harvesting mechanism in all hybrid devices was verified by several experimental methods (spectral analysis, time-resolved electroluminescence (EL), magnetic field effect on EL).