Sequential and Reversible Phase Transformations in Zero‐Dimensional Organic‐Inorganic Hybrid Sb‐based Halides towards Multiple Emissions

Zero-dimensional (0D) metal halides have drawn increasing attention due to the attractive structure dependent photoluminescence (PL) properties. Here, we report two new 0D organic-inorganic hybrid Sb-based halides, (MTP)6 SbBr6 Sb2 Br9 ⋅H2 O (MTP=Methyltriphenylphosphonium, crystal 1) and (MTP)2 SbBr5 (crystal 2), featuring a reversible structural phase transformation and tunable orange and red emissions upon dehydration and rehydration of H2 O molecules. Intriguingly, a subsequent heat treatment further enables the formation of glassy state (MTP)2 SbBr5 (glass 3) with near-infrared luminescence, moreover, a sequential reverse phase transformation from glass 3 to crystal 2 and 1 is triggered by acetonitrile and water vapor stepwise. The anti-counterfeiting demo based on the tunable and reversible PL switching is finally achieved and thus the phase structure engineering in 0D metal halides expands their multiple applications in optical fields.