Effect of stabilizer on sol ageing for CuO thin films synthesized by sol-gel spin coating technique

Abstract

Nanostructured CuO thin films were fabricated by sol-gel spin coating technique. Objective of this study was to investigate the effect of stabilizer concentration on the ageing behavior of sol that tunes the opto-electronic properties of CuO thin films. Thin films were synthesized by sol-gel spin coating technique and annealing temperature was optimized to enhance the crystallinity along with the optical properties. Polycrystalline monoclinic crystal structure of the annealed thin films was confirmed using X-ray diffraction (XRD) technique. Maximum crystallinity was evident for the optimized annealing temperature 550°C with crystallite size 31 nm. Direct optical band gap was decreased from 3.72 to 3.48 eV as the annealing temperature was increased from 450 to 550°C exhibiting red shift in the absorption spectra. Following optimization of the annealing temperature, molar ratio of precursor to stabilizer was varied from 1:1 to 1:3 leading to the stabilization of the sol extending from 1 hour to 24 hours. Such findings can be highly beneficial to exploit the advantages of long period ageing of sol for enhanced opto-electronic properties.