My research is mainly focused on using ultrafast nonlinear optical spectroscopy to investigate the optical and electronic properties of single-walled carbon nanotubes (SWNTs). My present project is try to use ultrafast visible and UV photons to generate (and detect) multiple electron-hole pairs in semiconducting single-walled carbon nanotubes through impact ionization processes. Impact ionization is essentially the inverse of Auger recombination, whereby a highly excited electron-hole pair loses energy by creating a new exciton from the vacuum state. Impact ionization has been discussed as a simple potential route to achieving high overall photon conversion efficiencies for solar cells.
