Revealing the internal heavy chalcogen atom effect on the photophysics of the dibenzo[<i>a,j</i>]phenazine-cored donor–acceptor–donor triad

Donor–acceptor–donor molecules containing heavy chalcogen atoms, which feature multi-color polymorphism, external-stimuli responsive luminochromism, thermally-activated delayed fluorescence, and room-temperature phosphorescence, have been developed.