Dynamic Luminescence Manipulation for Rewritable and Multi-level Security Printing

Security printing on paper is of particular significance, as paper still plays a dominant role in information storage. Several critical challenges, such as multiple-time uses and high-level security, need to be addressed to improve the practical application of security printing in different scenarios. To address these issues, understanding the inherent relationship between microenvironmental changes and photophysical properties of luminescent materials and rational control of their optical properties is crucial. Here, investigations of emission intensity and lifetime switching by manipulating the dynamic ionic coordination of Mn(II) complexes have been performed. Importantly, after gaining insight into the controllable luminescent properties of these Mn(II) complexes, the feasibilities of rewritable and multi-level security printing were demonstrated. We believe that controlling the reversible ionic coordination of luminescent materials could be considered a major step forward toward rewritable and multi-level security printing.