Crystal-Liquid-Glass Transition and Near-Unity Photoluminescence Quantum Yield in Low Melting Point Hybrid Metal Halides.

Hybrid metal halides (HMHs) are a class of materials that combine extraordinary photophysical properties and excellent processability. Their chemical variability allows for the solid-liquid transition toward melt-processable HMHs. Herein, we report the design and synthesis of zero-dimensional HMHs [M(DMSO)6][SbCl6], where the isolated octahedra of [M(DMSO)6]3+ and [SbCl6]3- are alternatively aligned in the crystal structure. The luminescent center of [SbCl6]3- enables the photogeneration of self-trapped excitons, resulting in broadband photoluminescence with a large Stokes shift and a nearly 100% quantum yield. Meanwhile, the release of DMSO ligands from [M(DMSO)6]3+ is controlled by the M-O coordination and thus a low melting point of ∼90 °C is achieved for HMHs. Interestingly, the glass phase is obtained by melt quenching, with a sharp change in photoluminescence colors compared to the crystal phase of melt-processable HMHs. The robust crystal-liquid-glass transition opens a new avenue to tailoring structural disorder and optoelectronic performance in organic-inorganic materials.