Regulating intermolecular interactions for stable multifunctional organic–inorganic metal halide hybrid glasses

Due to diverse properties complementary to their crystalline state, organic-inorganic metal halide hybrid (OIMH) glasses are drawing increasing attention. Nevertheless, the fundamental principles governing glass formation and crystallization in these materials remain elusive, significantly limiting their multifunctional applications. Here, high glass formation ability and tunable crystallization of glass are achieved through the regulation of intermolecular interactions. The π⋯π and C-H⋯π interactions among Bzmim⁺ (Bzmim = 1-benzyl-3-methylimidazolium) cations increase the melt viscosity and packing inefficiency of the structure, thereby facilitating the high glass formation ability of Bzmim₃SbCl₆ (B3SC6) and Bzmim₂SbCl₅ (B2SC5). The crystallization behaviour of these glasses is closely related to electrostatic attraction. The stronger electrostatic attraction and larger melt fragility in B3SC6 lead to a longer cooperative length of the supercooled liquid above T_g, resulting in a reversible and rapid crystal-glass transformation accompanied by high contrast luminescence switching upon heating. Conversely, the weaker electrostatic attraction and smaller melt fragility in B2SC5 result in a stable glass, and transparent glass ceramic can be fabricated by assisted nucleation and slow crystallization growth. This work highlights the important impact of intermolecular interactions on the formation and crystallization of OIMH glass, providing a design framework for engineering tailored properties for advanced applications in nonvolatile memory and photonic devices.