Naphthyridine-based emitters simultaneously exhibiting thermally activated delayed fluorescence and aggregation-induced emission for highly efficient non-doped fluorescent OLEDs

Luminescent materials simultaneously exhibiting superior luminescence efficiency, thermally activated delayed fluorescence (TADF) and aggregation-induced emission (AIE) properties in the solid state are eagerly required for highly efficient non-doped organic light-emitting diodes (OLEDs). Herein, two new emitters, namely ND-AC and CND-AC, featuring a naphthyridine or cyano-naphthyridine segment as the electron acceptor and an acridine unit as the electron donor were designed, synthesized and investigated. The nearly orthogonal molecular configuration of the target emitters not only endows them with small energy differences between singlet and triplet states for ensuring TADF character but also affords a remarkable AIE feature. Due to the high photoluminescence quantum yields, and excellent TADF and AIE characteristics, the doped and non-doped OLEDs based on ND-AC exhibit outstanding performances with maximum external quantum efficiencies of 16.8% and 12.0%, respectively. These results demonstrate that the naphthyridine-based emitters have a promising application in OLEDs.