An UV-resistant dynamic luminescent phosphor for anti-counterfeiting

Abstract

With multi-stimuli responsive luminescence, the ZnS-based optical materials show bright potentials in applications for advanced anti-counterfeiting, which still confront with poor ultraviolet (UV) resistance and photobleaching. This work proposes an efficient surface modification strategy to construct a core-shell ZnS:KBr,Mn2+@CaZnOS (ZKM@CaZnOS) composite phosphor, where a uniform thin layer of Ca(OH)2 firstly deposits on the ZKM particles then the controllable combination reaction on the surface generates an intimate layer of CaZnOS. The core phosphor ZKM possesses excitation wavelength dependent dynamic luminescence by combining the intrinsic luminescence and Mn2+ emission. The inert shell acts as a protection layer to greatly enhance the UV-resistance of the ZKM phosphor. After exposure to UV irradiation for 45 days, the ZKM@CaZnOS maintains over 90% of the initial luminescent intensity while the starting ZKM remains about 50%. The modified ZKM@CaZnOS phosphors show promising application in the portable UV resolvable anti-counterfeiting.