Submicron double-perovskite structured terbium based lanthanide chloride crystals: Room temperature synthesis, near-unity quantum yield and high-resolution X-ray imaging

Double-perovskite structured lanthanide halide (DPLH) materials, possessing remarkable photoluminescence and scintillation properties, have emerged as ideal candidates for applications in light-emitting diodes and X-ray imaging. However, fabricating high-performance submicron DPLH crystals remains a significant challenge. Here, we propose a modified supersaturated recrystallization (SR) method using eco-friendly solvents to synthesize sub-micron Cs2NaTbCl6 crystals at room temperature for the first time. The prepared Cs2NaTbCl6 exhibit a high photoluminescence quantum yield (PLQY) of 70.1 %, which can be further enhanced to near-unity through Ce3+ doping. The Cs2NaTbCl6:Ce demonstrate a high light yield of 53,200 photons MeV 1 and exhibit stable X-ray excited optical luminescence (XEOL). As a demon, flexible Cs2NaTbCl6:Ce embedded polymethyl methacrylate (PMMA) films as scintillator screens for X-ray imaging have been fabricated to show a low detection limit of 28.8 nGy/s and a high resolution of ~31.0 lp/mm. This work represents a significant advancement in the fabrication of DPLH materials, enabling high-performance photoluminescence and high-resolution X-ray imaging.