UC San Diego

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 illumination¹⁵⁻²⁹. 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