Novel Carbonyl/Nitrogen Polycyclic Frameworks for Developing Multi‐Resonance Materials with Narrow‐Spectrum Emissions

Organic luminescent materials with multi‐resonance (MR) characteristics are emerging as promising candidates for achieving high‐definition organic light‐emitting diode (OLED) displays. Currently, the major MR compounds are built with boron/nitrogen (B/N) ‐embedded polycyclic aromatic frameworks but suffer from complicated synthesis with low yields and poor solubility. Herein, a facile method to create carbonyl‐nitrogen (C═O/N)‐based MR compounds is reported in this work. A series of novel C═O/N MR compounds containing electron‐neutral, electron‐withdrawing, and electron‐donating aromatics are synthesized and characterized. These compounds exhibit good thermal stability and exceptional high solubility. X‐ray crystallographic analysis and theoretical simulations reveal their bended structures with high rigidity and MR features. They show blue to sky‐blue emissions with a narrow full width at half maximum (FWHM) of ∼20 nm in toluene solutions. When integrated into sensitizer‐free OLEDs, they exhibit narrow emission profiles with FWHM of ∼30 nm and provide good maximum external quantum efficiencies of up to 14.3%. The results presented in this work enrich the library of C═O/N‐based polycyclic frameworks and establish a versatile design roadmap for high‐performance full‐color MR luminescent materials.