Halogen-Regulated Luminescent Silver(I) Halide Complexes and the Gel Scintillation Screen for X-Ray Imaging

Metal halide scintillators have attracted continuously increasing interest for low-dose and high-resolution X-ray imaging, yet typical luminescent silver halides suffer from severe hygroscopicity and exciton quenching caused by Ag–Ag cluster aggregation. To address these challenges, we design and report mononuclear five-coordinate silver(I) halide complexes (dppb) 2 AgX·DMSO (X = I, Br, Cl) with 1,2-Bis(diphenylphosphino)benzene (dppb) ligand. Halogen substitution enables tunable broadband emission, while the chloride analogue achieves efficient thermally activated delayed fluorescence (TADF) and a high PLQY of 76%. The chloride analogue possesses more rigid AgClP 4 coordination environment compared with its bromide and iodide counterparts, enabling restricts excited-state relaxation, suppresses non-radiative decay, and preserves favorable singlet-triplet energetics and spin-orbit coupling. Meanwhile, the chloride analogue shows superior scintillation with a high light yield of 26631 photons/MeV, and a detection limit of 304.67 nGy air s −1 . Furthermore, a high spatial resolution of 20.2 lp mm −1 for X-ray imaging is achieved based on the transparent Ag-Cl composite gel scintillator screen. This work not only provides a promising design principle for achieving high scintillation in TADF-type Ag(I) halide complexes by halogen regulation, but also provide a new platform for Ag(I) halide complexes in X-ray imaging.