Emergence of a Lanthanide Chalcogenide as an Ideal Scintillator for a Flexible X-ray Detector.

The development of high-performance X-ray detectors requires scintillators with fast decay time, high light yield, stability, and X-ray absorption capacity, which are difficult to achieve in a single material. Here, we present the first example of a lanthanide chalcogenide of LaCsSiS4:1%Ce3+ that simultaneously integrates multiple desirable properties for an ideal scintillator. LaCsSiS4:1%Ce3+ demonstrates a remarkably low detection limit of 43.13 nGyair/s and a high photoluminescence quantum yield of 98.24%, resulting in a high light yield of 50480 ± 1441 photons/MeV. Notably, LaCsSiS4:1%Ce3+ exhibits a fast decay time of only 29.35 ± 0.16 ns, making it one of the fastest scintillators among all lanthanide-based inorganic scintillators. Furthermore, this material shows robust radiation and moisture resistance, endowing it with suitability for chemical processing under solution conditions. To demonstrate the X-ray imaging capacity of LaCsSiS4:1%Ce3+, we fabricated a flexible X-ray detector that achieved a high spatial resolution of 8.2 lp/mm. This work highlights the potential of lanthanide chalcogenide as a promising candidate for high-performance scintillators.