Modulation of halogens in organic manganese halides for high-resolution and large-area flexible X-ray imaging†

Manganese-based organic metal halides, due to their excellent optoelectronic properties and stable chemical nature, have been widely used in optoelectronic devices and sensors. In this study, through rational modulation of halogens, three novel zero-dimensional organic manganese halides [(C₆H₈N)₂MnX₄ (X = Cl, Br, and I)] were obtained by changing the halogen atom via the solvent evaporation method. Due to the d–d electronic transition of Mn²⁺ in the tetrahedrally coordinated [MnX₄]²⁻ polyhedron, all samples exhibit strong green emission. Notably,(C₆H₈N)₂MnBr₄ exhibited a remarkable light yield of 18 224 photons per MeV and a low detection limit of 1.9 μGy s⁻¹, which is below the X-ray diagnostic limit and even superior to that of commercial BGO scintillators. Moreover, a 9 cm × 9 cm flexible scintillator film was successfully fabricated by mixing (C₆H₈N)₂MnBr₄ crystalline powder with polymethyl methacrylate, and this film manifested superior radiation stability and an X-ray imaging resolution of 12.1 lp mm⁻¹. Notably, the X-ray images captured by the flexible film demonstrate distinguished clarity when adhered perfectly to curved metal sheets. The combination of excellent performance and facile solution processing opens new opportunities for low-cost, high-performance organic metal halide-based large-area flexible scintillators for X-ray detection and imaging.