Plasmon‐Enhanced Phosphorescent OLEDs With Suppressed Efficiency Roll‐Off for High‐Luminance Applications

ABSTRACT Phosphorescent organic light‐emitting diodes (OLEDs) hold great promise for display and lighting applications owing to their high efficiency and excellent color purity. However, their application in high‐luminance fields such as transparent displays and virtual reality is limited by severe efficiency roll‐off, primarily attributed to triplet‐triplet annihilation (TTA) and triplet‐polaron quenching (TPQ). In this study, we demonstrate that integrating a thin silver anode in close proximity to the phosphorescent emitter achieves a Purcell factor of 3.7, approximately three times that of conventional indium tin oxide–based devices. This configuration accelerates the exciton decay rate and reduces exciton density, thereby significantly suppressing both TTA and TPQ. As a result, the efficiency roll‐off is reduced from 57% to 11%. Notably, despite 64% of the energy coupling into surface plasmon polariton modes, the optimized device exhibits a 17% improvement in current efficiency at 20,000 cd/m 2 compared to conventional phosphorescent OLEDs with analogous structures, without requiring additional light extraction techniques. Moreover, the operational lifetime (LT90) is extended by five times. These findings highlight the potential of a simple plasmonic nanofilm approach for advancing high‐luminance phosphorescent OLEDs.