Hyperphosphorescent OLEDs: Harnessing the Power of MR‐TADF Terminal Emitters

Hyperphosphorescent organic light-emitting diodes (HP-OLEDs) represent an attractive solution to persistent efficiency roll-off and device stability issues, combining phosphorescent sensitizers with fluorescent terminal emitters to achieve efficient, narrowband emission. This review discusses advances in HP-OLEDs where the terminal emitter is a multiresonance thermally activated delayed fluorescence compound. Recent breakthroughs in device performance, including examples demonstrating both high maximum external quantum efficiencies (EQEmax) and excellent color purity, are highlighted. This review summarizes design strategies, challenges, and future directions for improving the efficiency, stability, and spectral performance of HP-OLEDs.