Achieving dynamic quintuple-mode luminescence in Ca3Ti2O7:Pr3+,Er3+ phosphor for anti-counterfeiting applications

Abstract

Multi-mode luminescent materials refer to materials that can emit light at different wavelengths or colors depending on the applied stimulus, which could provide enhanced security features and make it more difficult for counterfeiters to reproduce. Here, we report the achievement of multi-color dynamic anti-counterfeiting by using multi-mode luminescence material Ca₃Ti₂O₇:Pr³⁺,Er³⁺ as the luminescent inks. Ca₃Ti₂O₇:Pr³⁺,Er³⁺ exhibits quintuple modes of photoluminescence (PL), long persistent luminescence (LPL), photo-stimulated luminescence (PSL), mechano-luminescence (ML), and up-conversion luminescence (UCL) with rich emission colors. The PL color of the phosphors could be modulated from red to yellow-green when the pump wavelength changes from 254 to 365 nm. Moreover, the tunable color of the phosphors is modulated from yellow to green by prolonging the irradiation time of a 980 nm laser (0.6 W), which is attributed to the elaborate cooperation of the PSL and UCL behaviors. Finally, the anti-counterfeiting trademark based on Ca₃Ti₂O₇:Pr³⁺, Ca₃Ti₂O₇:Er³⁺ and Ca₃Ti₂O₇:Pr³⁺,Er³⁺ with attractive performance is designed for advanced anti-counterfeiting technology with exceptional security.