Halogen Content Tunes the Color Temperature of White Light and Afterglow in Zero-Dimensional Hybrid Indium Halides

Zero-dimensional (0D) organic–inorganic hybrid metal halides (OIMHs) have been a category of non-negligible candidates with potential application in light-emitting diodes (LEDs), optical information storage, and anticounterfeiting. Herein, we first obtained two 0D isomorphic indium-based OIHMs, namely, IBPAInCl6·H2O and IBPAInBr6·H2O (IBPA3+ = bis(3-aminopropyl)amine cation), and further prepared a family of crystal samples of mixed-halogen IBPAIn(Cl1–xBrx)6·H2O (x = 0.25, 0.5, and 0.75) with the strategy of halogen substitution, which integrated the bluish-white photoluminescence (PL) emission of IBPAInCl6·H2O and the orange PL emission of IBPAInBr6·H2O as a perfect pair of complementary colors affording white-light emission. Interestingly, the cold-warm-tunable white-light emission in single-metal-templated In-based OIMHs was realized for the first time via continuous halogen content control. Mechanistic studies disclose that the ratios of the emission intensities at higher energies and lower energies present a gradual variation tendency, resulting in cold-warm-tunable white-light emissions. Moreover, the ultralong afterglow of IBPAInCl6·H2O (1.1 s) that can be identified by the naked eyes was found to be facilely tuned by regulating the content of Br– anions. Hence, the crystal samples of halogen substitution in In-based halides were applied as anticounterfeiting/information storage materials to fabricate a time-resolved encryption system with high performance.