An Azaryl‐Ketone‐Based Thermally Activated Delayed Fluorophore with Aggregation‐Induced Emission for Efficient Organic Light‐Emitting Diodes with Slow Efficiency Roll‐Offs

Abstract Achieving the concurrent manifestation of thermally activated delayed fluorescence (TADF) and aggregation‐induced emission (AIE) within a single molecular system is highly sought after for organic light‐emitting diodes (OLEDs), yet remains rare. In this study, we present a novel TADF‐AIE dye, named PQMO‐PXZ, which has been designed, synthesized, and systematically characterized. Our comprehensive investigation, which includes structural analysis, theoretical calculations, and optical studies, evaluates the potential of PQMO‐PXZ for integration into OLEDs. Unlike existing azaryl‐ketone‐based emitters, PQMO‐PXZ exhibits red‐shifted emission and enhanced luminescence efficiency, due to its rigid structure and strong intramolecular charge transfer characteristics. Significantly, PQMO‐PXZ demonstrates pronounced AIE properties and TADF with a short delayed lifetime. When utilized as the emissive core, OLED devices based on PQMO‐PXZ achieve a respectable external quantum efficiency of up to 11.8 % with minimal efficiency roll‐off, underscoring PQMO‐PXZ's promise as a highly efficient candidate for OLED applications.