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.