Heterocyclic Modification Leading to Luminescent 0D Metal Organochalcogenide with Stable X-ray Scintillating Properties

Metal organochalcogenides (MOCs) are an emerging class of luminescent hybrid organic–inorganic semiconductors, whose structures and properties can be tuned by organic functionalization and substitutions of their metal and chalcogen elements. Herein, we present a new design strategy by heterocyclic modification, resulting in the transformation of prototypical two-dimensional (2D) silver phenylselenide (AgSePh) to a zero-dimensional (0D) silver pyridinylselenide (AgSePy) via the formation of Ag–N bonds. At room temperature, AgSePy shows strong and broad orange photoluminescence (PL; λ max = 636 nm, full-width-at-half-maximum = 111 nm, quantum yield = 64%) with a large 259 nm Stoke’s shift and a 3.4 μs lifetime. Using steady-state and time-resolved PL spectroscopy under varying temperature and oxygen conditions, we found AgSePy to exhibit air-stable luminescence and maintain a high PL quantum yield and a single exponential PL lifetime down to 4 K. Furthermore, AgSePy shows excellent thermal stability up to ∼250 °C and chemical stability against polar, nonpolar, and aqueous solvents at pH 3–14. Density functional theory calculations further confirm the 0D electronic structure. Finally, we successfully demonstrated the performance of AgSePy as an X-ray scintillator with an estimated light yield of ∼8,000 phe/MeV and a spatial resolution down to 0.080 ± 0.005 mm. Overall, this work provides a novel tactic to modify the structures and properties of MOCs, highlighting their structural richness and structure–property relationship, and introduces their new use as X-ray scintillators, encouraging further development in radiation detection and medical imaging.