Fig. 1: Energy levels and chemical structures of organic PersL materials with host-guest components.
From: Achieving trap-depth-tunable organic persistent luminescence through host energy-level engineering
a Energy level diagram and electron transition route for trap-induced PersL. b Trap depth regulation by guest energy-level engineering. c Trap depth regulation by host energy-level engineering. d Chemical structure of TADF molecules as guest (left) and host molecules (right). One guest and five host molecules were studied, including 2,7-bis(4-(9H-carbazol-9-yl)phenyl)−1,8-naphthyridine (CPND), 3,3’-(5’-(3-(pyridin-3-yl)phenyl)-[1,1’:3’,1”-terphenyl]−3,3”-diyl)dipyridine (TMPyPB), 2,4,6-tri([1,1’-biphenyl]−3-yl)−1,3,5-triazine (T2T), dibenzo[b,d]furan-2,8-diylbis(diphenylphosphine oxide) (PPF), diphenyl(4-(triphenylsilyl)phenyl)phosphine oxide (TSPO1) and bis[2-(diphenylphosphino)phenyl]ether oxide (DPEPO). Abbreviations and labels: host (H), guest (G), recombination center (R), trap (T), electrons (black balls), LUMO of the guest (GL), HOMO of the guest (GH), LUMO of the host radical anion (\({{{{\rm{H}}}}}_{{{{\rm{L}}}}}^{{{{\rm{\bullet }}}}-}\)), LUMO of the guest radical anion (\({{{{\rm{G}}}}}_{{{{\rm{L}}}}}^{{{{\rm{\bullet }}}}-}\)), and trap depth (ε).
