Bisphosphonium cation based metal halide glass scintillators with tunable melting points

Abstract

Organic–inorganic metal halide (OIMH) glass offers the advantages of large-scale production, high transparency, and minimal light scattering. However, undesired crystallization in OIMH glass can occur, leading to deteriorated transparency. Herein, a series of bisphosphonium organic cations were designed to construct Mn-based metal halide crystals with a photoluminescence quantum yield (PLQY) near unity, alongside the development of highly thermally stable OIMH glasses. Two strategies were employed to lower the melting point of OIMH: alkyl chain elongation and fluorine substitution. The (Hex-3,4-2F)MnBr₄·MeOH (Hex-3,4-2F = hexane-1,6-diylbis((3,4-difluorobenzyl)diphenylphosphonium)) crystal delivers a glass transition temperature of 100 °C and the highest T_g/T_m ratio (0.82) among OIMHs. The resulting OIMH glass exhibits a PLQY of 47.6%, achieves an impressive resolution of 25 lp mm⁻¹ in X-ray imaging, and remains transparent even after being heated at 90 °C for six weeks. These bisphosphonium-based OIMH glasses present a feasible design for the practical application of OIMH glasses in radiation detection.