Photoluminescence Switching and Non-Volatile Memory in Hybrid Metal-Halide Phase-Change Materials

Phase-change materials (PCMs) have spurred intensive studies for information storage owing to huge and drastic changes in physical properties (i.e., optical and resistivity) during the phase transitions between crystalline-amorphous and crystalline-melting-glassy states. However, limited switching properties and materials greatly hinder their development and applications. Herein, we report a pair of hybrid metal halides (R/S-2-HMM)₃SbCl₆ (2-HMM = 2-(hydroxymethyl)­morpholine cation) as model compounds of a new class of photoluminescent PCMs. They undergo a stable melt process and become amorphous glass by melt-quenching. The crystalline phase exhibits near-unity yellow photoluminescence with a 95% quantum yield due to the radiative recombination of self-trapped excitons in the excited state of [SbCl₆]^3– octahedra. The glass phase exhibits an orange emission with a very low quantum yield and good transparency in the 400–800 nm range. Drastic photoluminescence switching via the crystal-glass transition is exploited for rewritable phase-change memory, as exemplified by a 4 × 4 array model device. The robust crystal–liquid–glass phase changes in hybrid metal halides and drastic photoluminescence switching open a new avenue to PCMs for further applications in remote information storage, sensing, and display.