The effect of thermal annealing on photoelectrochemical responses of WO3 thin films

Abstract

The photoelectrochemical responses of WO3 thin films have been investigated as a function of annealing temperature up to 600 °C. WO3 films were deposited on unheated substrates by thermal evaporation followed by annealing at temperatures of 300, 500, and 600 °C for 5 h in air. The WO3 film annealed at 500 °C shows the best photoelectrochemical response due to improved crystallinity and enhanced light absorption in the long-wavelength region. Although the WO3 film annealed at 600 °C exhibits better crystallinity and increased light absorption properties, it shows a decreased photoelectrochemical response in comparison to the one annealed at 500 °C. These results strongly suggests that the reduced amount of electrochemical reaction sites for the film annealed at 600 °C film plays a significant role in influencing the decreased photoresponse. © 2007 American Institute of Physics.