Effect of annealing on photoluminescence and optical properties of porous anodic alumina films formed in sulfuric acid for solar energy applications

► Porous alumina tends to amorphous structure as the annealing temperature reaches 650 °C. ► Raman spectroscopy and XRD spectra has confirmed the amorphisation of porous alumina films. ► Refractive index increases while optical losses decrease with annealing temperature. ► Reflectivity increases to reach 97% when porous alumina films become amorphous. ► Photoluminescence spectra of porous alumina films in sulfuric acid displays α and β band peaks.