Multi‐Responsive 0D Organic–Inorganic Hybrid Cuprous Bromides Constructed via Ultra‐Facile Approaches for Multimodal Luminescent Anti‐Counterfeiting

Abstract Luminescent anti‐counterfeiting has the advantages of high secrecy, low cost, flexible design, simple operation, and convenient light‐regulation of luminescent materials, which makes it easy to achieve high‐level multimodal anti‐counterfeiting. Here, zero‐dimensional (0D) organic–inorganic hybrid luminescent crystals (TPA)CuBr₂ (TPA⁺ = [N(CH₂CH₂CH₃)₄]⁺) with multiple responses to ultraviolet (UV) light, water, and thermal stimulus are synthesized through an ultra‐facile approach for multimodal luminescent anti‐counterfeiting. Water‐sensitive (TPA)CuBr₂ could transform into 0D (TPA)₂Cu₄Br₆ upon external water stimulus, accompanied by the change of luminescence color from cyan to orange under UV light irradiation. Both (TPA)CuBr₂ and (TPA)₂Cu₄Br₆ exhibit high photoluminescence quantum yields, and long photoluminescence decay lifetimes. In addition, (TPA)CuBr₂ and (TPA)₂Cu₄Br₆ show reversible “on‐off” luminescence phenomena and excellent cycling stability under thermal stimulus. Exhilaratingly, multimodal anti‐counterfeiting luminescent labels with high‐security level could be fabricated based on the multiple responsive organic–inorganic hybrid cuprous bromides. Moreover, the test paper based on (TPA)CuBr₂ could be fabricated for the detection of trace water in isopropanol. This work demonstrates the capabilities of (TPA)CuBr₂ and (TPA)₂Cu₄Br₆ as high‐security anti‐counterfeiting materials and luminescent sensors, which provides an important reference for exploring 0D metal halides for high‐level luminescent anti‐counterfeiting.