Amended multimodal optical properties of Dy3+ for Latent wLED and high-security fluorescence anti-counterfeiting ink

Double perovskites of diyttrium magnesium titanate are synthesized by low-temperature combustion method at 1173 K - 4 h, marking a decrease in thermal budget 625 K - 5 h with conventional practice. From the UV–visible spectra, the bandgap is obtained as 3.653 eV. A series of Dy³⁺ ions are doped in the crystal lattice giving pure white emission at 353 nm excitation and red emission at 980 nm excitation. The crystal structure is confirmed by FESEM and Raman analysis. The optimal 2 wt% elemental doping is inveterate from the XPS analysis whereas the phosphors remain stable under extreme thermal conditions, realized from the TGA. Further monovalent Li⁺, divalent Sr²⁺, or trivalent Sm³⁺ ions are co-doped in the crystal matrix, which chiefly enhances the crystalline, optical, and luminescence properties for Li⁺ sensitization. These CIE parameters are amended to ideal white light with coordinates (0.326, 0.333), color temperature of 5819 K, and color purity of 2.5 %, signifying a novel ideal white light emission. Anti-counterfeit inks are prepared using PVA due to the red emission of the phosphor under NIR excitation, distinctive for double wavelength fluorescence printing ink technique to tackle serious counterfeiting.