Enhancing the Up-conversion luminescence using All dielectric Three-Dimensional multiscale anodized aluminum oxide nanowire structure

Light management at nanometric dimension for boosting the enhancement of photo luminescence from Lanthanide doped up-conversion nanoparticles (UCNPs) has evidenced epochal advancement attributed to their conspicuous emission properties and plethora of potential applications. In this work, a multiscale funnel shape three dimensional (3D) anodized aluminum oxide (AAO) nanowire topography is explored to improve up-conversion luminescence (UCL) of synthesized core shell (C/S) NaYF₄:Yb³⁺,Tm³⁺/NaYF₄ UCNPs dispersed in chloroform. The different hexagonally arranged AAO topographies, based on cost-effective and modified self-aggregation fabrication method, are presented. These unique topographies of nanowire structures provide archetypal for enhanced UCL and have been investigated to study the effect of light management in detail. The systematic studies indicate that UCL enhancement is substantiated by the prolonged light path due to multiple scattering, and guided modes in the length of nanowire structures with the modified surface topography hoisted by capillary force inside the nanowires. The length of the nanowire and structure's topographies are endorsed as structural parameters to tune the reflection as well as resonance mode for tuning the enhancement. The overall UCL enhancement for an optimized wire length and surface topography of AAO substrate is found to be ∼ 115 fold in ultra-violate regime at low excitation power density.