Center for Functional Nanomaterials Seminar
"Excitons in organic semiconductors: Elucidating the mechanism of singlet fission"
Presented by Tim Berkelbach, Chemistry Department, Columbia University
Wednesday, February 12, 2014, 11 am
CFN, Building 735, Conf. Rm. A
Center for Functional Nanomaterials Seminar Tim Berkelbach Excitons in organic semiconductors: Elucidating the mechanism of singlet fission Chemistry Department, Columbia University Wednesday, February 12, 2014 11:00 a.m. Bldg. 735 â€" Conf. Rm. A The generation of multiple excitons from a single absorbed photon has the potential to dramatically increase the efficiency of solar cells, however a microscopic understanding of the process remains elusive. I will present a theoretical formalism combining electronic structure and quantum relaxation theory for the simulation of multiple exciton generation in organic molecules, a process known as singlet fission. By calculating the optical response and real-time quantum dynamics, this work sheds light on the properties of charge-transfer excitations, including their role in the singlet fission process, and resolves a number of controversies in the literature. Specifically, we find that charge-transfer excitations can play a prominent role in mediating singlet fission, although the mechanism is qualitatively different in molecular dimers as compared to bulk crystals. . Host: Mark Hybertsen Joann Tesoriero Center for Functional Nanomaterials P.O. Box 5000 Bldg. 735 Upton, NY 11973 Tel: (631) 344-7791 Fax: (631) 344-7769 Tesoriero@bnl.gov