Abstract
Engineering of single material with multidirectional applications is of crucial for improving the productivity, low cost, flexibility and least power consumption, etc. To achieve these requirements, novel design structures and high performance materials are in urgent need. Lanthanide-doped nanophosphors have greatest strengths and ability in order to tuning its applications in various dimensions. However, nanophosphor applications in latent fingerprints visualization, anti-counterfeiting and luminescent gels/films are still in its infancy. This study demonstrated a simple strategy to enhance the luminescence of Tb3+ doped (1-11 mol %) La2Zr2O7 nanophosphors by conjugating the fluxes via simple solution combustion route. The photoluminescence spectra reveal intense peaks at ~ 491, 546, 587 and 622 nm arises from 5D4◊7FJ (J = 6, 5, 4, 3) transitions of Tb3+ ions, respectively. The highest emission intensity was achieved in the NH4Cl flux assisted nanophosphor as compared to NaBr and NH4F. The colorimetric images of fingerprints visualized using optimized nanophosphor on forensic related surfaces exhibit level –III ridge details, including sweat pores, width of the ridges, bifurcation angle, successive distance between sweat pores, etc. These results are decisive parameters which clearly supports the statement “no two persons have ever been found to have the same fingerprints”. The anti-counterfeiting security ink was formulated using nanophosphor and designed various patterns by simple screen printing and dip pen technology. The encoded information was decrypted only under ultraviolet 254 nm light. All the designed patterns are not just what it looks/feels like and how it works. As a synergetic contribution of enhanced luminescence of the prepared nanophosphor, the fabricated green-emissive films display excellent flexibility, uniformity and transparency in the normal and ultraviolet 254 nm light illumination. Aforementioned results revealed that prepared NH4Cl flux assisted La2Zr2O7: Tb3+(7 mol %) NPs are considered to be best candidate for multi-dimensional applications.
Enrichment of Luminescence via Incorporation of Fluxes in La2Zr2O7:Tb3+ Nanophosphors: One Material, Many Possibilities-Latent Fingerprint Visualization, Anti- counterfeiting, Luminescent Flexible Films