Solid-State Fluorescent Se QDs-Tb³⁺doped SiO₂for Multimodal Anti-Counterfeiting Applications

In this work, multicolour and near white-light-emitting Se-Tb³⁺ doped SiO₂ are synthesised via the sol-gel method. Due to the phase shift from cubic to amorphous in Se quantum dots (QDs), the absorption spectrum of the annealed Se-Tb³⁺ doped SiO₂ exhibited broad absorption in the lower wavelength region. Due to the combined effect of excitation-dependent blue emissions (cubic Se QDs) and enhanced multiple emission bands (Tb3+ ions), fluorescent c-Se-Tb³⁺ doped SiO₂ are color-tunable from blue to near white to green under different excitations. While Se QDs sensitizes and boosts Tb³⁺ fluorescence in its cubic phase, it quenches Tb3+ emission in its amorphous phase. Under 340 nm UV excitations, cool white emission (0.3040, 0.4074) with CCT value of 6426 K is obtained for c-Se-Tb³⁺doped SiO₂ (c37). Excitation-dependent photoluminescence colour tuning, shifting from blue to near white at lower c-Se QDs content and white to green at higher c-Se QDs content is observed in c-Se-Tb³⁺doped SiO₂. The dependence of fluorescence emission from Se-Tb³⁺ doped SiO₂ on crystallinity of Se QDs, Se concentration, and excitation wavelength is beneficial in realizing anti-counterfeiting and advanced solid color tunable lighting devices.