Electrochromic performance, wettability and optical study of copper manganese oxide thin films: Effect of annealing temperature


Falahatgar S. S. , GHODSI F. E. , TEPEHAN F. Z. , TEPEHAN G. G. , Türhan İ.

APPLIED SURFACE SCIENCE, cilt.289, ss.289-299, 2014 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 289
  • Basım Tarihi: 2014
  • Doi Numarası: 10.1016/j.apsusc.2013.10.153
  • Dergi Adı: APPLIED SURFACE SCIENCE
  • Sayfa Sayıları: ss.289-299

Özet

In the present work, the nanostructured copper manganese oxide (CMO) thin films were prepared from acetate based sol-gel precursors and deposited on glass and indium tin oxide (ITO) substrates by dipcoating technique. The films were annealed at 300, 400 and 500 degrees C in ambient atmosphere. The effects of annealing temperature on structural, morphological, wettability, electrochromic and optical properties of CMO thin films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDX), water contact angle measurement (WCA), cyclic voltammetry (CV) measurements and ultraviolet-visible (UV-vis) spectrophotometery. The presence of mixed oxide phases comprising of copper manganese oxide (CuMn2O4) and manganese oxide at different annealing temperature was confirmed by XRD patterns. The results showed that the Mn3O4 phase has been changed to Mn2O3 when the annealing temperature is increased from 300 to 500 degrees C. The FESEM images indicated that the granular surface morphology was sensitive to annealing temperature. EDX studies indicated that the thin films contained O, Mn and Cu species. Wettability studies showed that the water contact angle of the nanostructured CMO thin films coated on glass substrates was influenced by the variation of annealing temperature and the surface nature of thin films was changed from hydrophilic to hydrophobic. The results of CVs measurement indicated that the anodic and cathodic charge density and capacitance of all CMO samples decreased with increasing scan rate in potential range of -1-1 eV. Also, the annealed CMO thin film at 500 degrees C showed better electrochromic performance with respect to other samples at lower scan rate. The thickness, refractive index, extinction coefficient and optical band gap of thin films coated on glass substrates were calculated from reflectance and transmittance spectra using an iterative numerical method. The optical band gap of nanostructured CMO thin films increased with increasing annealing temperature. (C) 2013 Elsevier B.V. All rights reserved.