However, this excited-state character results in smaller Stokes shifts and lower utilization of triplet excitons. To circumvent these limitations, organic thermally activated delayed fluorescence (TADF) scintillators with strong twisted intramolecular charge transfer utilizing triplet excitons for RL emission have been developed, which utilizes triplet excitons for RL emission (Fig. ). Apart from an increase in scintillation light production has been achieved, the radiative lifetimes are significantly extended to the microsecond time scale and the emission FWHMs are also expanded to 70~100 nm.