Modulating Molecular Aggregations via Konjac Glucomannan for High‐Contrast Time‐Dependent Phosphorescence Color

Materials exhibiting time‐dependent phosphorescence color (TDPC) are attractive, but generally suffer from complex preparation processes and low‐color contrast. Herein, molecular aggregation regulation of 1‐pyrenecarboxylic acid (PyC) in the konjac glucomannan (KGM) matrix is proposed to realize high‐contrast TDPC. The steric hindrance of KGM enables isolated state, carboxyl dimer, and π‐stacking‐induced multimers of PyC with different phosphorescence wavelengths and lifetimes to coexist, leading to a typical TDPC evolution from red to blue‐green. The TDPC shows remarkable phosphorescence wavelength shift up to 182 nm and phosphorescence lifetime up to 788.43 ms, readily recognized by the naked eye. In addition, KGM, an edible natural polysaccharide, displays decent rheological properties suitable for screen printing, film casting, and 3D printing, making PyC‐KGM an eco‐friendly tool for multi‐dimensional information security applications. The work provides a simple yet efficient method for high‐contrast TDPC materials and affords a promising material for high‐level dynamic information encryption and anti‐counterfeiting.