Disguise as fluorescent powder: Ultraviolet-B persistent luminescence material without visible light for advanced information encryption and anti-counterfeiting applications

Persistent luminescent material (PLM) is promising candidate in anti-counterfeiting field. Specifically, Ultraviolet (UV) PLM without visible persistent luminescence (PersL) can realize information encryption with high concealment and security. However, UV-PLM has not yet been applied in anti-counterfeiting owing to the lack of invisible UV-PLM. Herein, we, for the first time, report a novel invisible ultraviolet-B (UVB) PLM and applied in advanced anti-counterfeiting and encryption field, exhibting its unique advantages. First, we prepared a novel series of UV-PLM, Mg2Ln2Ge3O11:Bi3+ (Ln = Gd, La, Y, and Lu) and then realized the tuning of PersL from 350 to 310 nm via element substitution. Specifically, Mg2Lu2Ge3O11:Bi3+ (MLG) can emit dim visible photoluminescence under 254 nm excitation and produce UVB-PersL without visible region after the excitation was ceased, which caused it appear like an ordinary fluorescent powder. Interestingly, the invisible UVB-PersL can be detected using a camera realizing the information encryption with high concealment. Moreover, owing to its unique optical properties, mixing MLG with different colors of fluorescent powder endows it with the ability to camouflage. Based on MLG, we designed a triple-mode information encryption method and demonstrated its unique advantages in the field of advanced anti-counterfeiting.