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.