Terahertz Spectroscopy: Probing Carrier Dynamics in Nanomaterials On Sub-Picosecond Time Scales

There is currently a world wide effort to make use of advances in nanotechnology to design next generation solar cells that could make economical solar energy a reality. One strategy pursued actively is using nanowires, nanotubes or nanorods in solar cells as efficient conduits for electron transport and extraction. Ultrashort far-infrared laser pulses are an ideal probe of free carriers in these nanomaterials capable of resolving carrier dynamics on femtosecond time scales. In this presentation new results obtained with time-resolved terahertz spectroscopy will be presented revealing why TiO₂ nanotubes, used to improve electron transport in dye sensitized solar cells, are not yet significantly outperforming nanoparticle films and how they potentially could. Far-infrared laser spectroscopy could also supply unique information addressing core challenges facing several other promising renewable energy and micro-electronic technologies. Some of these future directions will be discussed briefly.