Carbonyl-nitrogen multi-resonance emitters for efficient OLEDs with high color purity

Multi-resonance (MR) materials hold an intriguing feature of narrow emission spectra and have attracted considerable attention in the manufacture of high-definition organic light-emitting diodes (OLEDs). However, the majority of MR materials are composed by a boron-nitrogen skeleton, which is unfavorable for expanding the scope of luminescent materials with narrow emission spectra to meet various application demands. In this work, we wish to report a new carbonyl-nitrogen (C = O/N) skeleton of 5,12-dihydroquinolino[2,3-b]acridine-7,14-dione (QA), and three tailored C = O/N MR molecules are synthesized and fully characterized by crystallography, thermal measurement, cyclic voltammetry, steady-state and transient spectroscopy and theoretical calculation. They show efficient green emissions with narrow full width at half maximum (FWHM) of about 27 nm and high photoluminescence quantum yields of up to 93% in doped films. Efficient hyperfluorescence OLEDs are fabricated using these materials as emitters, providing pure green lights with electroluminescence peaks at 526‒538 nm, narrow FWHMs of 29‒33 nm, excellent external quantum efficiencies of up to 29.48% and small efficiency roll-offs. These results reveal that QA could be a potential skeleton for exploring efficient C = O/N MR molecules.