Versatile Molecular Functionalization for Inhibiting Concentration Quenching of Thermally Activated Delayed Fluorescence

Researchers emonstrate that even a small modulation in molecular geometric structures greatly affects concentration quenching of thermally activated delayed fluorescence (TADF) and can enhance the quantum efficiencies of solid-state photoluminescence (PL) and electroluminescence (EL). The exciton-quenching rates of TADF emitters show an exponential dependence on their intermolecular distance in thin films, revealing that electron-exchange interactions of triplet excitons, as described by the Dexter energy-transfer model, dominate the concentration quenching of TADF. This mechanism stands in marked contrast to those of conventional fluorescent and phosphorescent emitters involving Förster energy transfer.