Dual-Mode Label with Dynamic Cracking–Wrinkling Pattern and Ultralong-Lifetime Phosphorescence for Multilevel Anti-counterfeiting and Time-Resolved Message Encryption Applications

Constructing a dual-mode information encryption material with dynamic cracking-wrinkling structures and tunable luminescence properties is a promising way to enhance information security. However, it is hard to achieve multilevel information encryption due to the limited responsiveness and encryption capacity of current dual-mode information encryption materials. Here, we demonstrated a dual-responsive optical membrane that integrates highly encrypted ultralong-lifetime room-temperature phosphorescent (ULRTP) materials and mechanical response cracking-wrinkling structures toward multistage information encryption. First, the new ULRTP materials with ultralong-lifetime (2.66 s) and high phosphorescence quantum yield (PHQY, 35.3%) were synthesized by using boric acid, citric acid, and sodium bromide. In this system, the external heavy-atom effect (EHE) is induced by Br- anions, which can promote the intersystem crossing rate (ISC) and increase the PHQY. While the nonradiative decay rate of the triple excitons are effectively reduced by the electrostatic interaction between Na+ cations and Br- anions, which can significantly prolong the phosphorescence lifetime. Furthermore, the cracking-wrinkling patterns are induced by an ultraviolet/ozone-treated optical film. Under selective stimulation, this optical membrane can dynamically adjust its surface structure and phosphorescent color. This smart film with dynamic cracking-wrinkling and phosphorescence shows potential applications in anti-counterfeiting and message encryption.