Investigation of Solar Energy Transfer through Plasmonic Au Nanoparticle-doped Sol-derived TiO2 Thin Films in Photocatalysis and Photovoltaics

Titanium Dioxide (TiO2) films were elaborated using the Sol-Gel technique and subsequently used to study plasmonic photovoltaic and photocatalytic energy transfer enhancement mechanisms. TiO2 was chosen because of the unique optical and electrical properties it possesses as well as its ease of preparation and operational stability. The properties of sol-elaborated films vary significantly with processing environment and technique, and the sol formula; a systematic investigation of these variables enabled the selection of a consistent technique to produce relatively dense, crack-free TiO2 thin films. Localized Surface Plasmon Resonance (LSPR) energy transfer was investigated by integrating plasmonic Au nanoparticles into multi-layer wide-band gap semiconductor (TiO2) devices, and by doping strongly catalytic TiO2 anodes in a 3-electrode photochemical cell. An instant 3x photocurrent enhancement in the multilayer solar cell device was observed under 650nm light illumination, which suggests the presence of a resonant energy transfer. The focus of this work was to develop a systematic analysis of the actual mechanics of energy transfer responsible for the light-harvesting enhancements seen in previous studies of Au nanoparticle-TiO2 systems under visible illumination. This mechanism remains the subject of debate and models have been proposed by various researchers. A method is developed here to pinpoint the most influential of the proposed mechanisms.