Optical Properties of CuO Nanoparticles

Abstract

CuO nanoparticles were successfully prepared by a chemical method which has been widely studied as photothermal and photo conductive materials. The samples were characterized by X‐ray diffraction (XRD), Scanning Electron Microscopy (SEM), UV‐Visible spectroscopy and Photoluminescence Spectroscopy. The SEM image showed that the prepared product consists of spherical nanoparticles with narrow size distribution. The average crystallite size of CuO nanoparticles calculated from XRD pattern was 8 nm. The UV‐Visible absorption spectrum of CuO nanoparticles shows a strong blue shift compared to that of bulk. The band gap energy was calculated from the absorption spectra. Due to the high surface to volume ratio, CuO nanoparticles have high density of surface defects, interstitials and oxygen vacancies. Photo luminescence spectroscopy has been employed in order to explore the optical emission properties of CuO nanoparticles. The emission at 535 nm corresponds to the band edge emission and that at 600 nm is due to the oxygen vacancy. In addition to these two peaks there shows an additional peak at 657 nm which indicates the oxidation state of Cu.