Stepwise Emission Tuning of Thermally Activated Delayed Fluorescence Emitters from the Orange to Near-Infrared Region by Rational Molecular Design

Herein, we unveiled a rational molecular design to develop rigid and strong acceptors through interlocking followed by cyano substitution to tune the emission wavelength of thermally activated delayed fluorescence emitters from the orange (∼605 nm) to near-infrared (∼777 nm) region. Interlocking phenyl units in the 4,4'-(quinoxaline-2,3-diyl)dibenzonitrile core, paired with multicarbazole donors, resulted in a 70 nm red shift in emission. Further cyano substitution at the C2 and C7 positions of the dibenzo[a,c]phenazine-3,6-dicarbonitrile acceptor induced an additional 102 nm red shift. Consequently, organic light-emitting diodes with an emission wavelength range from orange to deep red were fabricated with an external quantum efficiency of >10%.