Near-Unity Green Luminescent Hybrid Manganese Halides as X‑ray Scintillators

The increasing demands in optoelectronic applications have driven the advancement of organic–inorganic hybrid metal halides (OIMHs), owing to their exceptional optical and scintillation properties. Among them, zero-dimensional (0D) low-toxic manganese-based scintillators have garnered significant interest due to their exceptional optical transparency and elevated photoluminescence quantum yields (PLQYs), making them promising for colorful light-emitting diodes and X-ray imaging applications. In this study, two OIMH single crystals of (Br-PrTPP)₂MnBr₄ (Br-PrTPP = (3-bromopropyl) triphenylphosphonium) and (Br-BuTPP)₂MnBr₄ (Br-BuTPP = (4-bromobutyl) triphenylphosphonium) were prepared via a facile saturated crystallization method. Benefiting from the tetrahedrally coordinated [MnBr₄]^2– polyhedron, both of them exhibited strong green emissions peaked at 517 nm owing to the d–d electron transition of Mn²⁺ with near-unity PLQYs of 99.33 and 86.85%, respectively. Moreover, benefiting from the high optical transparencies and remarkable luminescence properties, these manganese halides also exhibit excellent radioluminescent performance with the highest light yield of up to 68,000 photons MeV^–1, negligible afterglow (0.4 ms), and linear response to X-ray dose rate with the lowest detection limit of 45 nGy_air s^–1. In X-ray imaging, the flexible film made by the composite of (Br-PrTPP)₂MnBr₄ and PDMS shows an ultrahigh spatial resolution of 12.78 lp mm^–1, which provides a potential visualization tool for X-ray radiography.