Abstract:
To synthesize ZnO nanostructured powders with 12 different morphologies by gas phase and liquid phase reaction. Different morphologies were obtained, such as nanotetrapods with three different long legs, nanospheres, hollow spheres, flower-like nanosheets, flower-like nanorods, nanowires, nanorods, nanotubes and porous plates which were observed by scanning electron microscopy (SEM). Crystalline characteristics of ZnO nanoparticles indicated hexagonal structure wurtzite phase which were investigated by X-ray diffraction technique (XRD). Their porosity were meso-porous and non-porous materials which were measured by nitrogen absorption desorption method. Energy band gap were characterized by reflectance of ZnO powder by UV-Visible spectroscopy. It was found that the trend of crystallite size decreases with increasing of band gap energy. Crystal defects were observed by photoluminescence technique. The defects were depended on the amount of substance, time and temperature of reaction. In addition, the synthesized ZnO were employed for fabricating as anodes of dye sensitized solar cell (DSSC). The amount of dye absorption on ZnO powder was leached by 0.1 M of NaOH and then determined by UV-Visible spectroscopy. The highest surface area, the highest dye absorption was obtained. The overall efficiency of DSSC depended on energy and gap, crystal defect and dye adsorption. The band gap energy was related to the energy level of conduction band when the electron from dye was transferred to the electrode. Therefore, DSSCs with anodes fabricated from ZnO hollow spheres with the highest surface area showed the maximal efficiency of 0.49% because of high energy band gap, lowest of crystal defect and the highest of dye absorption.