Anchoring group regulation of bridging molecules enables brightly luminescent and ultra-stable Cs₂ZrCl₆@SiO₂ scintillator for high-resolution X-ray imaging

The lead-free perovskite Cs₂ZrCl₆ has recently attracted huge interest in X-ray imaging application. However, it generally exhibits unsatisfactory stability originating from the intrinsically ionic structure and low formation energy, which will hinder the future application. Herein, we design different anchoring groups (amino, sulfhydryl and thiocyanate) mediated nucleation and growth process for synthesis of Cs₂ZrCl₆ crystals coated by SiO₂ nanospheres, achieving Cs₂ZrCl₆@SiO₂-X (X = NH₂, SH, SCN) composites, respectively. Among these three samples, Cs₂ZrCl₆@SiO₂-SCN has an impressive photoluminescence quantum yield (PLQY) of 89 %. More importantly, it also manifests outstanding stability toward light illumination, heat and moisture. Such high PLQY and robust stability stem from the isolation effect due to tight anchoring, which separate perovskite crystals from each other and prevent particle aggregation. Finally, a large-area (113 cm²) scintillation screen based on Cs₂ZrCl₆@SiO₂-SCN@poly(dimethylsiloxane) (PDMS) and a commercial thin-film transistor (TFT) panel (16 cm × 13 cm, 125 μm pixel size) were used to fabricate an X-ray imaging detector, which showed a spatial resolution up to 4 lp mm⁻¹ beyond the upper limit of TFT panel and high-quality imaging capability of static objects. It is believed that this scintillator screen has a potential application in next-generation indirect X-ray detection and imaging.