(4n) 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.