Triplet Exciton Enhanced Radioluminescence of Ga3+/Tb3+ Metallacrown Scintillators for X-Ray Detection

The increasing demand for radiation detection in many applications has led to demanding requirements for scintillators. Realizing low-dose, pollution-free, and reliable X-ray detection has become a key technical challenge. Here, a triplet-enhanced lanthanide radioluminescence (RL) material Ga 3+ /Tb 3+ metallacrowns (Tb-1) is reported. This Tb-1 crystal emits bright green luminescence under ultraviolet light or X-ray excitation, and the emission intensity is 286 and 242 times that of Tb 3+ in inorganic salt, respectively. Tb-1 crystal is further passivated by trioctylphosphine oxide (TOPO), and the enhanced RL intensity is equivalent to that of commercial Tl-doped cesium iodide scintillator. In addition, RL of Tb-1–TOPO has an extremely narrow full width at half maximum and an excellent linear response to the X-ray dose rate. The detection limit is calculated to be 0.146 μGy s −1 , which is 38 times lower than typical medical imaging doses. Triplet-enhanced lanthanide RL provides new ideas for replacing scintillators that require high temperature synthesis processes such as inorganic phosphors and ceramics, and provides a new alternative scintillator material for flexible X-ray monitoring, bioimaging, radiotherapy, and other applications.