Tunable emission and photochromic properties of BaSrY4O8: Bi3+/Eu3+ phosphors for information encryption and anti-counterfeiting application

Photochromic luminescent materials have attracted much attention as a promising field in information encryption and anti-counterfeiting applications. Herein, a series of color-tunable with reversible photochromic BaSrY 4 O 8 : Bi 3+ /Eu 3+ phosphors were synthesized by the solid-state reaction method. The emission of BaSrY 4 O 8 : Bi 3+ , Eu 3+ phosphor exhibits tunable emission colors depending on the excitation wavelength or the Eu 3+ concentration. The effective energy transfers from Bi 3+ to Eu 3+ were observed, and the energy transfer mechanism was explained. Additionally, the color of the phosphor shows a reversible change from white to brown when exposed to different light stimuli (365 nm and 450 nm light). The reversible photochromic effect can be quantified by analyzing the changes in the emission spectra and diffuse reflectance spectra. The photochromic mechanism was investigated. Furthermore, an advanced anti-counterfeiting and encryption application was designed by combining multicolor luminescence with reversible photochromic under different light stimuli. The prepared anti-counterfeit pattern exhibits rapid luminescence modulation and noticeable multimodal changes in bright and dark fields. These results suggested that the BaSrY 4 O 8 : Bi 3+ /Eu 3+ phosphors are promising applications in information encryption and anti-counterfeiting.