Photoelectrochemical properties of CdS sensitized ZnO nanorod arrays: Effect of nanorod length

Abstract

The vertically aligned ZnO nanorod arrays were achieved from aqueous chemical route on soda lime and transparent conducting oxide coated glass substrates. The length of nanorods was varied from 1.6 μm to 4.5 μm by varying deposition time. The aspect ratio of ZnO nanorod was increased with increasing deposition time. Cadmium sulfide (CdS) nanoparticles have been subjected to self-assemble onto ZnO nanorods (ZNRs) using chemical bath deposition method. The synthesized CdS/ZnO nanorod arrays were characterized for their optical, structural, and morphological properties with UV-visible absorption spectroscopy (UV-Vis), x-ray diffraction, energy-dispersive x-ray analysis, x-ray photoelectron spectroscopy, contact angle measurement, and scanning electron microscopy. The cross-section images of the samples clearly depict different lengths of ZnO nanorods. UV-vis absorption spectrum shows the significant red shifting after covering of the CdS nanoparticles over the ZnO nanorods. The lengths of ZnO nanorod arrays are an effective parameter to improve the photoelectrochemical performance of CdS nanoparticles sensitized ZnO solar cells. We obtain a highest total light-to-electricity power conversion efficiency of 1.2% for relatively larger area (1 cm2) solar cells.