Achieving High Singlet-Oxygen Generation By Applying The Heavy-Atom Effect To Thermally Activated Delayed Fluorescent Materials

A bromine-substituted thermally activated delayed fluorescent (TADF) molecule AQCzBr(2) is designed with both small singlet-triplet splitting (Delta E-ST) and increased spin-orbit coupling (SOC) to boost intersystem crossing (ISC) for singlet oxygen generation. AQCzBr(2) nanoparticles (NPs) demonstrate high productivity of singlet oxygen generation (phi(Delta) = 0.91) which allows highly efficient photodynamic therapy toward cancer cells.