An Organic Emitter Displaying Dual Emissions and Efficient Delayed Fluorescence White OLEDs

Abstract The design and synthesis of one‐compound‐based white light organic solids that can be employed to fabricate efficient organic white light‐emitting devices (OLEDs) still remains a challenge. In this contribution, a classic organic donor–acceptor (D‐A) type molecule (PTZ‐BP) is presented, which is composed of phenothiazine (PTZ) as an electron donor and benzophenone (BP) as an electron acceptor. Intriguingly, PTZ‐BP displays dual emission and thermally activated delayed fluorescence properties. Its dual emission originates from locally excited state and intramolecular charge transfer excited state, respectively. PTZ‐BP‐doped thin film is used to fabricate efficient white light OLEDs with external quantum efficiency of 6.2%, which is among the highest values reported for the single‐emitter‐based small molecules white fluorescence OLEDs with similar Commission Internationale de L' Eclairage (CIE) coordinates so far.