Single excitable dual emissive novel luminescent pigment to generate advanced security features for anti-counterfeiting applications†
A novel strategy has been devised to develop a single excitable dual emissive luminescent pigment for the formulation of unclonable security ink. The new advanced security features of the ink have been demonstrated successfully and make it highly suitable for the printing of valuable products, such as currency, passports, pharmaceuticals, and so forth for protection against duplicity. The formulation of the single excitable dual emissive luminescent pigment is based on the unexplored combinatory concept of the fluorescence@phosphorescence phenomenon, which provides a new feature in the composite. It emits intense red color (611 nm) upon illumination with a 254 nm UV lamp excitation source and long persisting green color (532 nm) when the excitation source is switched off. To study the feasibility of the single excitable dual emissive luminescent security ink for commercial applications, the patterns printed using this ink were not only subjected to rigorous atmospheric conditions such as hot, cold and humid conditions for six months, but also examined after treatment with various bleaching agents (ethyl alcohol, ethyl acetate, xylene, acetone, soap solution and laundry detergent) to ensure their chemical stability. The security features printed using the single excitable dual emissive luminescent security ink were found to be very stable against all of these stringent conditions. Hence, the exceptional results obtained using the single excitable dual emissive luminescent security ink offer a new pathway to prevent counterfeiting by generating advanced security features.