Organic Light-emitting Devices Based on Phosphorescent Hosts and Dyes

Phosphorescent dyes may lead to more efficient electroluminescent devices, since triplets should be formed in a 3-fold excess compared to singlets. Efficient devices are presented here that have been constructed using phosphorescent dye–doped layers as both the electron transporting and emitting layer. Triplet energy transfer from the host Ir(ppy)3 to the red phosphorescent dopant PtOX (see Figure) was observed directly.