A two-step hydrothermal synthesis of CeO2/CdS nanocomposite for photovoltaic application: an investigation on surface morphology, structure, optical and electrical properties

Abstract

CeO2 nanocrystals possess superior optical and electronic properties due to their unfilled electronic orbitals. However, the wide bandgap of CeO2 limits its application in the visible region. Therefore, we combined CdS with CeO2 for band gap engineering of the nanocomposite and to obtain enhanced optoelectronic properties. Spherical and rectangular shaped CeO2/CdS nanoparticles were prepared by a facile two-step hydrothermal synthesis method. The effects of altering molar concentrations of the precursors on the morphology, structure, optical and electrical properties of the nanocomposites were systematically studied. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDXA) were used to swot the structure, morphology, and composition of the CeO2/CdS nanoparticles, respectively. The average particle size and microstrain of the nanoparticles were estimated from the XRD peak widths. The estimated average crystallite size was found to be 6–13 nm for the CeO2/CdS nanocrystals. Raman and XPS spectra also confirmed the presence of different elemental composition in the nanocomposites. The optical properties were studied by UV-Visible diffused reflectance spectroscopy and Photoluminescence (PL) spectroscopy. The band gap values estimated for the synthesized CeO2/CdS nanocomposites were in the range of 2.34–2.39 eV. The nanocomposite sample with molar ratio Ce:Cd = 1:2, demonstrates the least reflectance in the visible light spectra. A blue emission band was observed at 473 nm in photoluminescence spectra. The vibrational modes were detected by Fourier Transform Infrared (FTIR) spectroscopy. The electrical properties of the CeO2/CdS nanoparticles were explicitly analyzed and the enhancement of current was observed under illumination. The stimulating optical and electrical properties of CeO2/CdS nanocomposites make it the most promising material for photoelectric devices and solar cell applications.