Dye-sensitized solar cell using sprayed ZnO nanocrystalline thin films on ITO as photoanode

Abstract

ZnO thin films had been successfully prepared by spray pyrolysis (SP) technique on ITO/Glass substrates at different substrate temperature in the range 250–400°C using Zinc acetylacetonate as precursor. The X-ray diffraction studies confirmed the hexagonal wurtzite structure with preferred orientation along (002) plane at substrate temperature 350°C and the crystallite size was found to vary from 18 to 47nm. The morphology of the films revealed the porous nature with the roughness value of 8–13nm. The transmittance value was found to vary from 60% to 85% in the visible region depending upon the substrate temperature and the band gap value for the film deposited at 350°C was 3.2eV. The obtained results revealed that the structures and properties of the films were greatly affected by substrate temperature. The near band edge emission observed at 398nm in PL spectra showed better crystallinity. The measured electrical resistivity for ZnO film was ∼3.5×10−4Ωcm at the optimized temperature 350°C and was of n-type semiconductor. The obtained porous nature with increased surface roughness of the film and good light absorbing nature of the dye paved way for implementation of quality ZnO in DSSCs fabrication. DSSC were assembled using the prepared ZnO film on ITO coated glass substrate as photoanode and its photocurrent – voltage performance was investigated.