The temperature dependence of the delayed emission provides confirmation that NOBNacene is TADF active. TADF in emitters with large ΔEST have previously been reported by Lu et al. in a D-A type violet emitter CZ-MPS that exhibited a very long td of 4.85 ms linked to a DEST of 0.58 eV. The authors ascribed the TADF to proceeding via intermediate triplet states. The kRISC value of NOBNacene was calculated to be 3.74 × 10 3 s -1 , which is slower than what reported for DOBNA (1.6 × 10 4 s -1 , in 1 wt% PMMA) , but faster than for α-3BNMes (5.9 × 10 2 s -1 , in 1 wt% PMMA).