CdS sensitized ZnO electrodes in photoelectrochemical cells
Tran Chien Dang, Duy Long Pham, Huu Lam Nguyen and Van Hoi Pham
Abstract
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 1 M KCl and 0.1 M 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
