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

Abstract

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 twodimensional (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 timeresolved 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 Xray 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.