The color-tunable persistent luminescence of Pr3+-activated Ca2Sb2O7 with double anti-counterfeiting potentiality

The persistent luminescence (PersL) materials Ca₂Sb₂O₇:Pr³⁺ were prepared by traditional high-temperature solid-state method. We systematically investigated the crystal structure, band structure, photoluminescence, PersL performance by X-ray diffraction diagrams, Materials Studio calculation, photoluminescence (PL) spectra, PersL spectra and CIE coordinate analysis. The PL and PersL are attributed to the Sb⁵⁺ → O^2? transition of the matrix and the 4f-4f transition of Pr³⁺ ion. For the sake of explaining the impact of various traps on PersL performance, thermoluminescence (TL) tests were performed on the optimal sample after diverse charging and discharging times. It was concluded that shallow traps have priority over deep traps in capturing electrons, and the electrons in the shallow traps were preferentially released. The highlight of this work is that the PL and PersL color can be adjusted by regulating the Pr³⁺ doping concentration when these samples were excited by a single excitation wavelength, so as to achieve a double anti-counterfeiting effect. Furthermore, the color change of PersL is different from that of PL. The luminescent patterns can make a difference as the change of concentration and time, forming a dynamic anti-counterfeiting mark that distinguishes in color and time. Thus, Ca₂Sb₂O₇:Pr³⁺ has a bright application prospect in dynamic anti-counterfeiting field.