Studies on bundle like ZnO nanorods for solar cell applications

•We prepared bundles like ZnO nanorods by simple sol gel dip coating method.•Growth mechanism is proposed for the formation of bundle like ZnO nanorods.•Achieved power conversion efficiency of 0.83% for bundle like ZnO nanorod.

Bundle like structured ZnO nanorods and vertically aligned ZnO nanorods have been prepared by simple sol–gel dip coating method on ITO substrate. The X-ray diffraction pattern shows that the prepared ZnO samples are of hexagonal phase, the scanning electron microscope images reveal the formation of bundle like ZnO nanorods and aligned ZnO nanorods. The high resolution transmission electron microscope images also show the presence of nanorods. The average diameter and length of the nanorods in the bundle of ZnO nanorods and vertically aligned ZnO nanorods are 200 nm, 1.5 μm and 100 nm, 1.8 μm respectively. Dye sensitized solar cells have been assembled using N719 dye as sensitizer and the conversion efficiencies of the vertically aligned ZnO nanorods and bundle like ZnO nanorods thin film based solar cells have been found to be 0.74% and 0.83%, respectively.