Rational design of isophthalonitrile-based thermally activated delayed fluorescence emitters for OLEDs with high efficiency and slow efficiency roll-off.

Two fluorescent emitters, 3DMACIPN and 4DMACIPN, bearing an isophthalonitrile unit as an acceptor core and multiple 9,9-dimethyl-9,10-dihydroacridine donor moieties were designed and synthesized. These emitters feature high thermal stability and thermally activated delayed fluorescence characteristics with relatively short delayed lifetimes (0.99 and 1.69 μs for 3DMACIPN and 4DMACIPN, respectively). By employing these TADF emitters doped into 4,4′-Bis( N -carbazolyl)-1,1′-biphenyl host as emissive layers, a green OLED achieved a maximum EQE of 10.0% and slow efficiency roll-off at a high luminance. [ABSTRACT FROM AUTHOR]