Sb3+-Doped Indium-Based Halides Enable Multimodal Anticounterfeiting and Plant-Growth Lighting via Tunable Emission

Low-dimensional hybrid metal halides (HMHs) have emerged as promising multifunctional phosphors due to their soft structural and compositional diversity. However, combining multiple emissive channels, including fluorescence, phosphorescence, and afterglow, within a single material platform remains nontrivial. Here, we develop a series of zero-dimensional (5-MBI)3In1–xCl6:x% Sb3+ crystals with diverse luminescent behaviors. Specially, (5-MBI)3InCl6 exhibits blue fluorescence and green phosphorescence with a lifetime of 173.22 ms. However, Sb3+ ion doping introduces an intense self-trapped exciton (STEs) emission peaking at 650 nm through efficient radiative transition, characterized by a large Stokes shift (292 nm) and a full width at half-maximum of 183 nm. Meanwhile, this incorporation significantly elevates the photoluminescence quantum yield (PLQY) from 6.41% to 73.27%. Furthermore, (5-MBI)3In1–xCl6:x% Sb3+ displays composition-dependent thermal quenching behavior between 78 and 298 K, spanning normal, zero, and antithermal quenching. The combination of high-efficiency, broadband, and thermally adaptive emission enables applications in multimodal optical anticounterfeiting and plant-growth lighting. This work establishes a versatile zero-dimensional HMH platform for engineering coupled emissive pathways in soft halide systems.