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Tuesday, December 09, 2008
09:00 AM - 10:00 AM
CNLS Conference Room (TA-3, Bldg 1690)


Charge Carrier Dynamics and Energy Transfer Processes in Nanostructures

Kirill Velizhanin
New Mexico State University

Extensive studies of charge carrier dynamics and energy transfer processes on nanometer length scale are motivated by their great application potential in highly efficient light harvesting and photovoltaic cells and a variety of molecular electronic devices. Accurate theoretical modeling of these processes requires fully quantum mechanical description and remains a challenging task. During the first part of the talk we will discuss recently developed numerically exact quantum mechanical multilayer multiconfiguration time-dependent Hartree scheme capable of accurate modeling of the charge and energy transfer dynamics in nanostructures comprising up to several hundred degrees of freedom. We compare the performance of the proposed methodology with various approximate methods such as the Redfield description and the non-equilibrium golden rule master equation. The second part of the talk will be focused on photo-induced multiple-carrier generation (also referred as the carrier multiplication) dynamics in semiconductor nanocrystals. Specifically, we propose the exciton scattering model to describe the carrier multiplication and the following relaxation processes. Using this model, numerical simulations of the carrier multiplication quantum efficiency in PbSe and PbS nanocrystals have been performed, and the results show good agreement with reported experimental data.

Host: Andrei Piryatinski, T-1