Simple/Efficient Phosphor-Only Emitting Systems: From Sky-Blue to Warm-White Organic Electroluminescence Based on a Novel Bipolar Phosphorescent Emitter as Host

An efficient WOLED employing simple/advanced phosphor-only emitting system based on a novel bipolar sky blue phosphorescent host realizes high-quality warm-white EL emission with the CIEx,y coordinates of (0.42, 0.45) and very high EQE (22.4%) / PE (65.4 lm W−1) level.