Preparation Of Nanocrystalline CdS Films And TiO₂/CdS Core-Shell Heterostructures Nanorod Films And Their Photoelectrochemical Properties

Since the beginning of the 20^th century, it has been an important way to solve the energy crisis and environment pollution by using solar energy. And thus solar cell that converts the sunlight into electricity has become the focus of the researches. CdS belongs to the II-VI group semiconductor material, and the band gap was 2.42 eV, Being a typically photoelectron material. CdS is the most widely studied nanocrystalline semiconductor as a photoanode in photoelectrochemical (PEC) cells because of its suitable band gap, long lifetimes, and easy fabrication. As a kind of cheap and safe semiconductor material, TiPO₂ has been extensively investigated in the field of solar cells. But it can not absorb visible light for its wide band-gap. One way to solve this problem is to use arrow band-gap semiconductor material to sensitive it. CdS with a narrow band-gap can realize the sensitization of TiO₂ electrodes.In this thesis, we first prepared CdS powder by a hydrothermal method, and then fabricated nanocrystalline CdS thin film electrodes by a doctor-blade technology. We also studied the influence of air annealing temperature on photoelectrochemical properties of the films and found the CdS thin films annealed at 380℃in air for 30 min possessed the best photoelectrochemical properties.After preparing the TiO₂ nanorods electrode using the doctor-blade technique, we further fabricated TiO₂/CdS core-shell heterostructures nanorods film electrodes using a simple and low-cost chemical bath deposition and measured the photoelectrochemical property of this new electrode in the solar cells. We also investigated the influence of the different deposition time on the cell performance and compared the performance with those of pure TiO₂ nanorods and CdS nanoparticles film as well as CdS nanoparticles deposited TiO₂ nanoparticles (P25) film photoelectrodes.