Expanding Multiple‐Resonance Structure of a Double‐Borylated Skeleton by Fusing with Indolocarbazole a Multiple‐Resonance Donor for Narrowband Green Emission

Abstract

AbstractDouble‐borylated multiple‐resonance (MR) skeletons are promising templates for high performance, while the chemical design space is relatively limited. Peripheral segments are often used to decorate/fuse MR skeletons and modulate the photophysics but they can also cause unwanted spectral broadening. Herein, a narrowband MR emitter ICzDBA by fusing an MR‐featured donor segment indolocarbazole into a double‐borylated MR skeleton is developed. In ICzDBA, the nitrogen atom located away from the core benzene ring can also contribute to the generation of the overall MR‐featured distribution through the long‐range conjugation effect, along with the other boron/nitrogen atoms on the phenyl center. Thus, ICzDBA in toluene displays a narrowband emission peaking at 507 nm with a full width at half maximum of merely 20 nm (0.09 eV). Moreover, organic light‐emitting diode devices using ICzDBA emitter exhibit ultrapure green emission with Commission Internationale de l'Eclairage (CIE) coordinates of (0.27, 0.70) and a high external quantum efficiency of 32.5%. These results manifest the importance of MR characters of peripheral decorations/fusions in preserving the narrowband features of MR skeletons, which provides a solution for further expanding MR structures with well‐maintained narrowband characters.