Progress of stimuli-responsive fluorescent materials with time-dependent optical properties for information...

Information security and anti-counterfeiting technologies are facing increasingly severe challenges worldwide. Traditional static anti-counterfeiting methods, being relatively easy to replicate, are gradually becoming inadequate to meet high-end security demands. In recent years, time-dependent stimuli-responsive optical materials have emerged as a focus of research for next-generation anti-counterfeiting and encryption systems, owing to their dynamic and tunable optical behaviors as well as their capacity for encoding information in the time domain. These materials exhibit time-evolving optical properties-such as luminescence color, intensity, lifetime, or polarization state-in response to external stimuli like light, pH, or chemical environments, often demonstrating reversible relaxation or specific kinetic behaviors. Based on these materials, information anti-counterfeiting and encryption systems can only reveal authentic data within specific time windows and enable self-destruction of information, which significantly enhance anti-counterfeiting complexity and security. This review systematically summarizes recent advances in the design strategies, response mechanisms, and applications of such materials, covering systems including metal-organic frameworks (MOFs), perovskite nanocrystals, organic small molecules, carbon nanodots (CDs), and smart hydrogels. It highlights their application potential in multilevel encryption, dynamic information storage and self-erasing labels. The article also identifies current challenges, such as strong reliance on UV light, insufficient dynamic control precision, and biocompatibility issues. Finally, it outlines future research directions, including multimodal stimulus responses, AI-assisted design, organic-inorganic hybrid systems, and environmentally friendly materials, to promote the practical application of these technologies in high-security anti-counterfeiting and encryption systems.