Understanding the role of alcohols in the growth behaviour of ZnO nanostructures prepared by solution based synthesis and their application in solar cells†
We report the successful control of the ZnO nanostructure morphology by a simple solution method using alcohols such as methanol, ethanol, butanol, hexanol, octanol and decanol as solvents. Morphology changes were noticed from nanodots to nanorods and back to nanodots with respect to the length of the alkyl group associated with the solvents as revealed by FESEM and TEM analysis. XRD analysis revealed the presence and purity of the prepared ZnO nanostructure. The optical properties of the ZnO nanostructures were investigated using UV-visible spectroscopy and photoluminescence spectroscopy. The changes in the defect state concentration were analyzed using XPS spectra. The PL spectra revealed the dependence of the UV and visible emission intensities on the defect states, size and length of the ZnO nanostructures. Furthermore, we demonstrate that the synthesized ZnO nanostructures are good candidates for the fabrication of photoanodes in Dye Sensitized Solar Cells (DSSCs). The power conversion efficiency of such DSSCs was found to vary according to the ZnO morphology.