Defect Regulation Strategy of Porous Persistent Phosphors for Multiple and Dynamic Information Encryption

Abstract Optical encryption technologies based on persistent luminescence material have currently drawn increasing attention due to the distinctive and long‐lived optical properties, which enable multi‐dimensional and dynamic optical information encryption to improve the security level. However, the controlled synthesis of persistent phosphors remains largely unexplored and it is still a great challenge to regulate the structure for optical properties optimization, which inevitably sets significant limitations on the practical application of persistent luminescent materials. Herein, a controlled synthesis method is proposed based on defect structure regulation and a series of porous persistent phosphors is obtained with different luminous intensities, lifetime, and wavelengths. By simply using diverse templates during the sol–gel process, the oxygen vacancy defects structures are successfully regulated to improve the optical properties. Additionally, the obtained series of porous Al 2 O 3 are utilized for multi‐color and dynamic optical information encryption to increase the security level. Overall, the proposed defect regulation strategy in this work is expected to provide a general and facile method for optimizing the optical properties of persistent luminescent materials, paving new ways for broadening their applications in multi‐dimensional and dynamic information encryption.