Enhanced luminescence of Dy-activated in-situ synthesized LaAlO3/MgO nanocomposites for cool wLED and latent finger printing applications

Abstract

In the current study, a series of trivalent Dysprosium doped La1-xDyxAlO3/MgO (with x = 0, 1, 3, 5, 7 and 9 mol. %) nanophosphor composites have been synthesized via Pechini sol-gel method. Structural properties were analyzed using XRD, Rietveld refinement and FESEM. The prepared nanophosphors exhibit rhombohedral/face-centered structure. The bandgap values of the nanophosphors were found to be in the range of 5.39–5.75eV. At the sintering temperature of 900 °C, La1-xDyxAlO3/MgO (x = 5 mol.%) nanocomposite exhibit significant enhancement in the white light emission as compared to La1-yDyyAlO3 (y = 5 mol.%). PL intensity of composite further increases with the rise in sintering temperature up to 1200 °C. Dexter's theory and Burshtein model when applied to PL and TRPL profiles unveil the d-d energy transfer mechanism that shifts from donor-acceptor to donor-donor transfer with dopant concentration. Other exemplary colorimetric and luminescence-based parameters such as, CRI, CCT, life-time, energy transfer efficiencies and probabilities indicate the potential suitability of fabricated phosphor for w-LED and imaging applications. The optimized nanophosphor composite, i.e., La1-xDyxAlO3/MgO (x = 5 mol.%) has been explored for Latent Finger Printing and it successfully identified all the levels-1, 2 and 3 features of fingerprint.