| AVS 57th International Symposium & Exhibition | |
| Energy Frontiers Topical Conference | Thursday Sessions |
| Session EN-ThP |
| Session: | Energy Frontiers Topical Conference Poster Session |
| Presenter: | K. Williams, University of Texas at Austin |
| Authors: | W. Tisdale, University of Minnesota K. Williams, University of Texas at Austin B. Timp, University of Minnesota D. Norris, University of Minnesota E.S. Aydil, University of Minnesota X.-Y. Zhu, University of Texas at Austin |
| Correspondent: | Click to Email |
In typical semiconductor solar cells, photons with energies above the semiconductor bandgap generate hot charge carriers that quickly cool before all of their energy can be captured, a process that limits device efficiency. Although fabricating the semiconductor in nanocrystalline morphology can slow this cooling, the transfer of hot carriers to electron/hole acceptors has not yet been thoroughly demonstrated. We use time-resolved optical second harmonic generation to observe hot electron transfer from colloidal lead selenide nanocrystals (PbSe NCs) to a titanium dioxide electron acceptor (TiO2). With appropriate chemical treatment of the nanocrystal surface, this transfer occurs much faster than expected. Moreover, the electric field resulting from sub-50 femtosecond charge separation across the PbSe-TiO2 interface impulsively excites coherent vibrations of the TiO2 surface atoms, whose motions can be followed in real time.