Enhanced Performance in Cesium Tellurium Chlorine by Hafnium Alloying for X‐Ray Computed Tomography Imaging

Abstract The term “light yield” (LY) refers to the ability of scintillator materials to convert high‐energy radiation into visible light. A higher LY corresponds to improved energy and spatial resolution in detectors. The enhancement of scintillator material performance is a crucial aspect of their development. In this study, the Cs 2 TeCl 6 (CTC) double perovskite microcrystals is synthesized, and the broadband yellow emission shows a high degree of matching with the Charge‐coupled Device (CCD). However, the LY of CTC is poor for practical applications in X‐ray imaging. The scintillation performance is significantly enhanced through hafnium alloying. The LY increased from ≈4167 to 38 523 photons/MeV, and the detection limit decreased from 948 to 258 nGy s −1 . The underlying mechanism of Te 4+ ions emission is systematically explored through density function theory (DFT) analysis, along with investigations into pressure‐dependent photoluminescence, temperature‐dependent photoluminescence, and low‐temperature thermoluminescence. Furthermore, a flexible X‐ray scintillator screen with an outstanding high spatial resolution of 15.9 lp mm −1 is successfully fabricated. This work not only represents a substantial advancement in the scintillation performance of Te 4+ ions emission double perovskite microcrystals but also provides an effective strategy for the development of the next generation of halide scintillators.