The design of an extended multiple resonance TADF emitter based on a polycyclic amine/carbonyl system

The development of multiple resonance thermally activated delayed fluorescence (MR-TADF) materials possessing narrow emission spectra has attracted significant attention as emitters for high colour purity organic light emitting diodes (OLEDs). In this work, a simple design strategy is introduced to construct an MR-TADF emitter,DDiKTa, through dimerization of the known MR-TADF emitterDiKTa. This design permits concentration quenching to be largely suppressed, which is a known weakness of previously reported MR-TADF emitters. OLEDs based onDDiKTashow an EQE(max)of 19% at a doping concentration of 9 wt%. The electroluminescence spectrum is red-shifted into the green, producing a rare example of a green-emitting MR-TADF OLED.