Polycyclic Aromatic Hydrocarbons with a Boron‐Doped Zigzag/Armchair Topology: A Boron‐Edging Strategy for Organic Narrowband Emitters

Abstract Control over molecular topologies and/or heteroatom doping of polycyclic aromatic hydrocarbons (PAHs) may alter their electronic structures and achieve desirable physical properties. Herein, this work challenges boron‐doping and edge‐transformation of π‐extended PAHs. We successfully synthesized a series of large‐size PAHs featuring a boron‐doped zigzag/armchair edge topology through one‐pot multifold Scholl cyclization reaction. Two of them possess the desired C 3 ‐symmetric and unexpected unsymmetrical C 54 B 3 nanographene frameworks, respectively, thus illustrating triply boron‐edging manipulations of hexa‐ peri ‐hexabenzocoronene. Detailed studies reveal that such boron‐doped edge topology significantly inhibits their excited‐state molecular vibrations and thereby produces narrowband emission characteristics. The full width at half maximum (FWHM) values of their fluorescence spectra are as small as 12–18 nm, which have never been observed for pristine boron‐doped π‐system and are among the smallest values reported for organic emitters. Their solution‐processed organic light‐emitting diodes (OLEDs) display extremely narrowband electroluminescence, and additionally, the obtained FWHM of only 23 nm represents the narrowest one reported for red OLEDs.