Charge transport in nanostructured materials for solar energy conversion studied by time-resolved terahertz spectroscopy

Spectra of far-infrared conductivity contain useful information on charge transport at nanoscopic length scales. However, decrypting the mechanisms and parameters of charge transport from the measured spectra is a complex task in nanostructured systems: in particular, the conductivity is strongly influenced by charge carrier interaction with surfaces or interfaces between constituents of the composite material as well as by local field effects. Here we review our work on transient far-infrared conductivity in polymer:fullerene bulk heterojunctions and in bare and dye-sensitized semiconductor nanoparticles. Measurements performed by time-resolved terahertz spectroscopy are complemented by Monte-Carlo calculations which clearly link the charge transport properties and the terahertz conductivity spectra.