Thermally activated delayed fluorescence properties of through-space charge-transfer-type organic molecule depending on solvent polarity

We investigate the photophysical properties of a newly synthesized molecule, 2PhCz-3PhTrz-DMeCz, which has two phenyl carbazole (PhCz) donors and a triphenyl triazine (3PhTrz) acceptor connected by a dimethyl carbazole (DMeCz) spacer. This architecture enables both through-bond charge-transfer (TBCT) and throughspace CT (TSCT) interactions. In polar solvents, the molecule exhibits enhanced photoluminescence quantum yield (PLQY) and reverse intersystem crossing rate (kRISC). Theoretical calculations show that polar solvents reduce the dihedral angle between PhCz and DMeCz in the excited states, increasing hole delocalization across the molecule. Our finding highlights that the conformational change of the target molecule is strongly influenced by the solvent polarity, resulting in distinct photophysical behavior.