Stimuli‐Responsive and Defect‐Regulated Luminescent Organic Metal Halide for High‐Security Anti‐Counterfeiting and Force Sensing

Abstract Smart materials with stimuli‐responsive luminescence hold considerable potential for anti‐counterfeiting and sensing applications. However, achieving multimode‐responsive luminescence and luminescence modulation remains a significant challenge. Herein, a smart 0D organic metal halide hybrid (OMH) (C 9 NH 20 ) 6 [Pb 3 Br 12 ] exhibiting temperature/moisture/mechanical force‐responsive luminescence switching and tunable responsive luminescence color is reported. The heat‐activated luminescence switching originates from a crystal structure transformation involving small molecule extraction. The recovery of the transformed structure under cooling and ambient conditions exposure through small molecule reinsertion is highly sensitive to moisture. Interestingly, defects in the recovered structure can be controlled, bringing a pathway to tune the luminescence color. Moreover, 0D (C 9 NH 20 ) 6 [Pb 3 Br 12 ] exhibits self‐recovering mechanical force‐responsive luminescence switching driven by structure deformation. Based on these stimuli‐responsive properties, its applications in time‐dependent high‐security anti‐counterfeiting and handwriting recognition are demonstrated. This study not only provides new insights for designing smart stimuli‐responsive luminescent OMH materials but also highlights the potential of (C 9 NH 20 ) 6 [Pb 3 Br 12 ] as a versatile platform for advanced anti‐counterfeiting and force sensing applications.