Efficient Sky‐Blue Bipolar Delayed Fluorescence Luminogen for High‐Performance Single Emissive Layer WOLEDs

Abstract Luminogens with high photoluminescence efficiencies and high triplet (T₁) energy levels are desired to achieve high‐performance white organic light‐emitting diodes (WOLEDs). In this work, a sky‐blue luminogen (DCB‐BP‐SFAC) with enhanced delayed fluorescence in aggregated state, bipolar carrier transport ability and high T₁ energy level is developed. DCB‐BP‐SFAC exhibits bright sky‐blue electroluminescence (EL) in both non‐doped and doped OLEDs with maximum external quantum efficiencies of 14.8% and 23.5%. DCB‐BP‐SFAC can function as efficient host for green, orange and red phosphorescent materials as well as thermally activated delayed fluorescence emitters with excellent EL performance. In addition, fluorescence/phosphorescence hybrid and all‐fluorescence WOLEDs with a single emissive layer are fabricated by adopting DCB‐BP‐SFAC as emitter and host simultaneously. The all‐fluorescence WOLED shows two‐color warm‐white light with good EL efficiencies of 47.1 cd A⁻¹, 46.2 lm W⁻¹, and 19.1%. The excellent performance of these OLEDs demonstrates the great application potential of DCB‐BP‐SFAC in practical display and lighting devices.