Spectroscopic characteristics and characterizations of CaAl12O19-based phosphors for anti-counterfeiting applications and performance predictions

Abstract

The CaAl₁₂O₁₉/ZnO (CAO/ZO), CaAl₁₂O₁₉/MoS₂ (CAO/MS), and CaAl₁₂O₁₉/LiPF₆ (CAO/LPF) phosphors with different mass percentages were synthesized. The CAO/ZO and CAO/MS phosphors contained no other impurities except the target products, but CAO/LPF phosphor also contained LiF and Li_xPO_yF_z impurities due to the high temperature thermal decomposition of LPF. The fine particles of ZO, MS or LPF were uniformly attached to the surface of CAO, forming a special interface contact. The coupling CAO with ZO and MS significantly reduces the optical band gap (Eg) value of CAO, while LPF coupling CAO does not affect the Eg value of host lattice. The CAO/ZO, CAO/MS, and CAO/LPF phosphors were shown to be sky blue, blue, and dark blue, respectively, during the photoluminescence characterization, which resulted in the emission peaks that were predominantly concentrated at 487, 467, and 459 nm, respectively. An intelligent algorithm model was used to predict the photoluminescence properties of CAO-based phosphors, and it demonstrated exceptional predictive ability. The CAO/ZO, CAO/MS and CAO/LPF phosphors exhibit different photoluminescence properties due to the radiative recombination of localized excitons, type I band arrangement and impurity promoting electron and hole recombination, respectively. Photoluminescence applications show that the CAO-based phosphors demonstrate multimodal fluorescence anti-counterfeiting under different excitation wavelengths.