Lanthanide(III)‐Cu<sub>4</sub>I<sub>4</sub> Organic Framework Scintillators Sensitized by Cluster‐Based Antenna for High‐Resolution X‐ray Imaging
Xiangmei Liu, Ruhua Li, Xueli Xu, Yangyang Jiang, Wenjuan Zhu, Yu Yao, Feiyang Li, Xiaofang Tao, Shujuan Liu, Wei Huang, Qiang Zhao
Abstract
Abstract Scintillator‐based X‐ray imaging has attracted great attention from industrial quality inspection and security to medical diagnostics. Herein, a series of lanthanide(III)‐Cu 4 I 4 heterometallic organic frameworks (Ln‐Cu 4 I 4 MOFs)‐based X‐ray scintillators are developed by rationally assembling X‐ray absorption centers ([Cu 4 I 4 ] clusters) and luminescent chromophores (Ln(III) ions) in a specific manner. Under X‐ray irradiation, the heavy inorganic units ([Cu 4 I 4 ] clusters) absorb the X‐ray energy to populate triplet excitons via halide‐to‐ligand charge transfer (XLCT) combined with the metal‐to‐ligand charge‐transfer (MLCT) state (defined as the X/MLCT state), and then the 3 X/MLCT excited state sensitizes Tb 3+ for intense X‐ray‐excited luminescence via excitation energy transfer. The obtained Tb‐Cu 4 I 4 MOF scintillators exhibit high resistance to humidity and radiation, excellent linear response to X‐ray dose rate, and high X‐ray relative light yield of 29 379 ± 3000 photons MeV −1 . The relative light yield of Tb‐Cu 4 I 4 MOFs is ≈3 times higher than that of the control Tb(III) complex. X‐ray imaging tests show that the Tb‐Cu 4 I 4 MOFs‐based flexible scintillator film exhibits a high spatial resolution of 12.6 lp mm −1 . These findings not only provide a promising design strategy to develop lanthanide‐MOF‐based scintillators with excellent scintillation performance, but also exhibit high‐resolution X‐ray imaging for biological specimens and electronic chips.