Designing vivid green Sr9Al6O18:Er3+ phosphor for information encryption and nUV excitable cool-white LED applications

Advanced forensic applications and optoelectronics both heavily rely on rare earth (RE) element activated luminous phosphor materials. We have used a single-phase green-emitting Sr9Al6O18:Er3+ (1–11 mol%) (SAO:Er) nanophosphor to detect latent fingerprints (LFPs) and white light-emitting diodes (w-LEDs). The X-ray diffraction and Rietveld refinement were used to examine crystallographic data. The phosphors showed vivid-green luminescence when stimulated by 378 nm, a near ultraviolet (nUV). The concentration of Er3+ ions is observed to affect the photoluminescence emission (PLE) intensity, reaching its highest value for 5 mol% doping. The optimized phosphor is used in latent finger print (LFP), lip print (LP) and anti-counterfeiting (AC) applications. Under 378 nm excitation, multilevel features of the phosphor-attached LFPs could be clearly identified. The high colour contrast between the ridge and valley lines made for an excellent observation. We have developed simple brush and screen-printing methods for creating a variety of patterns using our custom anti-counterfeit security ink. In addition to this, the obtained AC tags exhibit high resolution and long-term durability. These characteristics clearly demonstrated that the current phosphor is an excellent luminescent material for data storage applications.