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

Abstract 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 SbBr 6 Sb 2 Br 9 ⋅H 2 O (MTP=Methyltriphenylphosphonium, crystal 1) and (MTP) 2 SbBr 5 (crystal 2), featuring a reversible structural phase transformation and tunable orange and red emissions upon dehydration and rehydration of H 2 O molecules. Intriguingly, a subsequent heat treatment further enables the formation of glassy state (MTP) 2 SbBr 5 (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.