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

Abstract

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 Ga3+/Tb3+ 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 Tb3+ 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.

Aggregation-induced emission organic metal halide complex for X-ray scintillation

“…25 However, their potential as scintillators has been largely underexplored, with very few cerium and lanthanidebased organic metal complexes reported to exhibit low light yields. 26,27 Also, the presence of heavy atoms in these organic metal complexes often leads to long-lived phosphorescent emissions, which is undesirable for dynamic X-ray imaging, high-energy particle physics research, and many other applications. Therefore, further the exploration of organic metal complexes is necessary to develop efficient, rapid, and solutionprocessable scintillators.…”

Lanthanide Organic–Inorganic Hybrids for X-ray Scintillation and Imaging

“…The high coupling and spectral overlap between the organic ligands and lanthanide ions facilitate efficient intersystem crossing, converting some of these excitons from singlet states to triplet states in the organic molecules. The triplet-state energy is then transferred from the organic ligands to the lanthanide ions through nonradiative resonance energy transfer, resulting in strong XEL emission. , …”

“…The triplet-state energy is then transferred from the organic ligands to the lanthanide ions through nonradiative resonance energy transfer, resulting in strong XEL emission. 20,21 To assess the feasibility of Eu-pba and Tb-pba for practical applications, we investigated the hydrolytic, radiation, and thermal stabilities of both complexes. PXRD analyses revealed that the structures of Eu-pba and Tb-pba remained unchanged when exposed to different relative humidity (RH) conditions ranging from 45% to 100% for 24 h (Figure 2d).…”

“…Scintillating MOFs featuring inorganic metal centers as luminescent chromophores have remained limited. Examples of these include Ln-BDC (Ln = Eu or Tb), Ln-Cu 4 I 4 , Ln­(ox)­(COO)­(phen)­(H 2 O) (Ln = Eu or Tb), and Ln-MOF-76 (Ln = Tb or Eu), to name a few. − …”

Recent Advances in Fast-Decaying Metal Halide Perovskites Scintillators

“…1,2 With the growing demand for radiation detection, the requirements for scintillators are increasing. 3 Designing ultrabright and ultrafast scintillators has been a primary goal in this field since high light yield can realize detection at low irradiation dosage; ultrafast decay time can realize good time resolution and response rate of detectors. 4 Scintillators are approaching their theoretical limit in light yield, but there is still much potential for improvement in the decay time/response time.…”