Aggregation-induced narrowband isomeric fluorophores for ultraviolet nondoped OLEDs by engineering multiple nonbonding interactions

Traditional donor-acceptor type organic luminescent materials usually suffer from unfavorable spectral broadening and fluorescence quenching problems arising from strong inter/intra-chromophore interactions in aggregation state. Here, two ultraviolet carbazole-pyrimidine isomers (named o-DCz-Pm and m-DCz-Pm) with novel aggregation-induced narrowband phenomenon are constructed and systematic investigated by experiments and theoretical simulations. Benefitting from strengthened steric hindrance and multiple noncovalent interactions, the nonradiative decay, vibrational motion, and structural relaxation of singlet state can be effectively suppressed in aggregation state. Consequently, the electroluminescence peak of 397 nm, full width at half maximum of 21 nm and external quantum efficiency of 3.4% are achieved simultaneously in nondoped o-DCz-Pm-based device. This work paves an avenue toward the development of high-performance narrowband nondoped ultraviolet materials and organic light-emitting diodes.