CdS sensitized ZnO electrodes in photoelectrochemical cells

In this work, ZnO nanocrystalline thin films were obtained by evaporating Zn films using a thermal evaporation technique and then thermal treatment. The results show that after annealing at 300, 350, 400 and 450 C for 6 h, the obtained ZnO thin films have macro-structures. The results show that at an annealing temperature of 450 C, the ZnO thin film has the best optical properties for photo-electrodes. The incorporation of cadmium sulfide (CdS) into ZnO macro-structure thin films was investigated. A CdS thin film was vacuum-deposited onto the pre-deposited ZnO film by the thermal evaporation technique. The obtained ZnO and ZnO/CdS bilayer films were characterized by x-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The ZnO/CdS bilayer film was used in a photoelectrochemical (PEC) cell as a working electrode and a platinum electrode as a counter electrode. The electrolyte solution contained 1M KCl and 0.1M Na2S. The results show that the cell with the ZnO/CdS bilayer electrode had significantly improved photoelectric properties in comparison with that of the pure ZnO thin films. The best thickness of the CdS thin film deposited on ITO/ZnO substrates was around 70 nm. © 2010 Vietnam Academy of Science & Technology.