Lasers, Electrons and Nanotubes: A Roadmap to Affordable Solar Technology

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. However, these ‘electron highways' have not always lived up to expectation. I use ultrafast far-infrared laser pulses to directly probe free carriers in nanomaterials on femtosecond time scales. Some of my most recent work revealed 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 technologies. Some of these future directions will be discussed briefly.