Plasmonic Effect Enhanced Photocurrent in Nanostructured TiO2 Films Decorated with Gold Nanoparticles

In this study we present the plasmonic effect enhanced photocurrent in gold (Au) decorated on nanostructured TiO2 films (Au@TiO2). The Au@TiO2 electrodes were successfully prepared by means of vacuum evaporation, followed by thermal annealing. It was found that the average size of Au nanoparticles depends on the thickness of the deposited Au layer and the morphology of nanostructured TiO2 films. Strong plasmonic resonance absorption effects were observed in the samples of Au deposited on TiO2 nanoparticle films (Au@TiO2-NPs) where the resonance absorption peaks shifted to red wavelengths ranging from 534 nm to 617 nm, when Au nanoparticles size changes from 14 nm to 65 nm. For the Au deposited on TiO2 nanowire films (Au@TiO2-NWs), we found that the resonance absorption peak with a large absorbance was located at 547 nm. Photovoltaic properties of the plasmonic solar cells based on Au@TiO2 films as a working electrode were investigated. The results show that the enhancement in photocurrent caused by the plasmonic effect of the Au nanoparticles was strongly dependent on both their size and density.