Spatiotemporally Resolved Anti‐Counterfeiting via Multicomponent Zero‐Dimensional Metal Halides with Anti‐Kasha Emission

Abstract 0D organic‐inorganic metal halides (OIMHs) with excitation‐wavelength‐dependent emissions have emerged as ideal materials for multiplexed anti‐counterfeiting and information encryption. However, exploring multiple fluorescence/phosphorescence emissions stemming from distinct active centers within OIMHs remains challenging. Here, a phosphonium salt, [BCDBP]Br (BCDBP = butyldicyclohexyl(2′,6′‐dimethoxy‐[1,1′‐biphenyl]‐2‐yl)phosphonium), which exhibits room‐temperature phosphorescence (RTP) and anti‐Kasha emission, is synthesized. This phosphonium salt is successfully employed to prepare a series of 0D OIMHs [BCDBP] ₂ Zn _1−x Mn _x Br ₄ . The [BCDBP] ₂ ZnBr ₄ preserves RTP and anti‐Kasha behavior originating from the organic unit [BCDBP] ⁺ while simultaneously achieving self‐trapped exciton (STE) emission from [ZnBr ₄ ] ²⁻ . Further analyses confirmed that the incorporation of [ZnBr ₄ ] ²⁻ also suppresses non‐radiative decay, boosting the PLQY and extending phosphorescence lifetime. Furthermore, Mn ²⁺ doping introduces [MnBr ₄ ] ²⁻ emission centers, enabling [BCDBP] ₂ Zn _0.998 Mn _0.002 Br ₄ to exhibit rich excitation‐wavelength‐dependent emission from three distinct emissive centers: [BCDBP] ⁺ , [ZnBr ₄ ] ²⁻ , and [MnBr ₄ ] ²⁻ . This work successfully integrates an organic unit exhibiting anti‐Kasha emission with two distinct inorganic emissive centers into a single material platform, where all components remain optically active and selectively addressable under specific excitation conditions. The strategy of assembling multimodal emissions within a single material demonstrates exceptional potential for advanced optical encryption and anti‐counterfeiting applications.