Narrow Band Red Emission Fluorophore with Reasonable Multiple Resonance Effect

Abstract Developing boron‐based emitters in red region with a narrow band spectrum is crucial and challenging for optoelectronic applications. Herein the authors report novel emitters with reasonable multiple resonance (MR) effect by utilizing a CC bond type connection instead of conventional CN bond. The designed emitters BP‐2DPA and DBP‐4DPA exhibit narrowband pure red emissions with photoluminescence (PL) maxima of 599, 605 nm with a full width half maximum (FWHM) of 34 nm and high PL quantum yield of 91.3, 96.4%, respectively. Moreover, compared to reported MR emitters, the synthesis of BP‐2DPA and DBP‐4DPA has resulted in a high yield near to 40% with ease to scale in grams. The designed rigid moieties show reasonable MR effect with atomically highest occupied molecular orbital and lowest unoccupied molecular orbital separations. The fabricated organic light‐emitting diodes based on BP‐2DPA and DBP‐4DPA possessed an external quantum efficiency of 11.3% and 15.1%, pure red emission with electroluminescence maxima at 605 and 617 nm, a narrow FWHM of 42 and 44 nm respectively. The corresponding CIE coordinates are well approaching near to red color NTSC requirements. This is the first work reported with this strategy for achieving narrow emission spectrum for pure red color emitters.