High‐Performance Red OLEDs Enabled by an Organoboron‐Nitrogen‐Carbonyl‐Hybridized Multiresonant Emitter

Abstract Organoboron‐nitrogen‐carbonyl‐hybridized ( h ‐BNCO) frameworks are emerging templates for developing high‐performance multiresonant (MR) emitters, but their potentials have not been fully explored. In this study, a novel red MR emitter, namely, h ‐BNCO‐3, is developed by decorating two diphenylamine moieties onto a h ‐BNCO MR skeleton ( h ‐BNCO‐2). Compared with the green backbone, h ‐BNCO‐3 achieves a substantial emission redshift of 76 nm while retaining a narrow full width at half maximum (FWHM) of 45 nm (0.16 eV) in toluene. Moreover, the common advantages of integrating a carbonyl group in B/N‐based systems, e.g., significant nπ * contribution in the triplet manifolds, are obvious in h ‐BNCO‐3. Thus, h ‐BNCO‐3 obtained a fast reverse intersystem crossing rate ( k RISC ) of over 10 5 s −1 . The optimized non‐sensitized organic light‐emitting diode (OLED) based on h ‐BNCO‐3 achieved red emission with an external quantum efficiency (EQE) of 26.4%. Moreover, by further employing a phosphor as a sensitizer, the h ‐BNCO‐3‐based OLED can reach an impressive EQE of 38.0%, which is among the best results of red MR‐OLEDs. This work demonstrates the effectiveness of integrating carbonyl into organoboron‐nitrogen‐based frameworks with peripheral decorations for enhancing k RISC , offering new insights for developing high‐performance MR emitters based on h ‐BNCO systems.