Achievement

Most alternative solar cell designs rely on interfacial electron transfer to separate photogenerated excitons into free carriers; however, understanding and control of this often-inefficient process has been limited by the heterogeneity of most nanostructured samples and the inherent difficulty in tracking photogenerated free electrons. In collaboration with the Wise Group at Cornell, IGERT Fellow Carmella Calabrese measured the relaxation dynamics of free electrons in PbSe nanocrystals using ultrafast pump-probe spectroscopy. To quantify generation and relaxation of free carrier electron in PbSe nanocrystals, Carmella and her collaborators employ a newly developed continuum IR probe that covers the entire vibrational spectrum (< 400 to >4000 cm-1) in a sub-100fs pulse. These studies will improve understanding of electron transfer at interfaces and potentially lead to improved photovoltaic devices.