TiO2/CdS nanocomposite films: fabrication, characterization, electronic and optical properties

Tran Chien Dang, Duy Long Pham, Ha Chi Le and Van Hoi Pham

Abstract

In this work, TiO₂ nanocrystalline thin films were obtained through evaporating Ti films by electron beam deposition (EBD) followed by thermal treatment. The results show that after annealing at 300, 400 and 450 °C for 8 h, the obtained TiO₂ thin films have nanoparticle and nanorod structures of 15–30 nm diameter and 100–300 nm length. At 750 °C for 8 h, the rutile phase was formed. The incorporation of cadmium sulfide (CdS) into TiO₂ nanoparticle thin films was investigated. A CdS thin film was vacuum deposited onto the pre-deposited TiO₂ film by a thermal evaporation technique. The obtained TiO₂ and TiO₂/CdS nanocomposite films were characterized by x-ray diffraction (XRD) and a field emission scanning electron microscope (FE-SEM). The TiO₂/CdScomposite film was used in a photo-electrochemical (PEC) cell as a working electrode and in a platinum electrode as a counter electrode. The electrolyte solution contains 1 M KCl and 0.1 M Na₂S. The results show that the cell with the TiO₂/CdS composite film electrode has significantly improved photoelectric capability in comparison with that of pure TiO₂ thin films, and the best thickness of the CdS thin film deposited on the ITO/TiO₂ substrates is 70–140 nm.