The Scintillating Dynamics of Self‐Trapped Exciton Endowed/Unendowed by Thermally Activated Delayed Fluorescence

Abstract Triplet generation and control are widely studied in high‐energy scintillating materials, owing to their critical roles in thermally activated delayed fluorescence (TADF) and energy‐transfer processes. However, X‐ray excited inorganic scintillators, such as Cs 2 ZrCl 6 , present various defect traps in the self‐trapped exciton states. Hence, the mobility of the hot carriers that participate in scintillating dynamics is disorderly, and they may contribute to TADF or suppress the TADF pathway. This study prepares a series of Cs 2 ZrCl 6 : x%m‐MTDATA (x% = 0%–10%) organic–inorganic hybrid scintillators to achieve tunable photoluminescence (PL) and radioluminescence (RL) through a directional energy‐transfer pathway. This work highlights the different scintillating carrier dynamics of Cs 2 ZrCl 6 : x%m‐MTDATA under ultraviolet or X‐ray excitation. The introduction of m‐MTDATA into Cs 2 ZrCl 6 could increase the trap depths and ensure thermal quenching under X‐ray excitation, rather than inducing thermal activation, resulting in a weak X‐ray excited afterglow output and fast RL decay time. These findings provide a paradigm for future research on organic–inorganic hybrid X‐ray scintillators, opening new opportunities for detecting high‐energy radiations.