Aqueous chemical growth of ZnO disks, rods, spindles and flowers: pH dependency and photoelectrochemical properties

Suitable morphology for fast electron transportation is a crucial requirement for photoelectrochemical (PEC) solar cells. Highly oriented and well defined zinc oxide (ZnO) nano/micro-scale structures were grown on the glass and FTO coated glass substrates. The grown nanostructures have been characterized by X-ray diffraction pattern (XRD), scanning electron microscope (SEM) and optical absorption techniques. XRD patterns confirm high crystalline quality of ZnO with hexagonal wurtzite structure. SEM micrographs show the formation of disk, rod, spindle and flower-like morphologies at different pH values ranging from 5 to 10. The PEC solar cell configuration of ZnO/0.5 M Na2SO4/graphite has been used to record the current voltage (I V) and capacitance voltage (C V) characteristics of the films. The junction ideality factor (n(l)), series and shunt resistance (R-s and R-sh), flat-band-potential (V-fb), donor concentration (N-D), fill factor (FF) and efficiency (eta) have been estimated. Energy band diagram of ZnO and Na2SO4 electrolyte has been constructed. (C) 2011 Elsevier Ltd. All rights reserved.