Phonon-induced relaxation in PbSe quantum dots

PHYS 574

Svetlana V. Kilina, SKILINA@U.WASHINGTON.EDU and Oleg V. Prezhdo, Department of Chemistry, University of Washington, Seattle, WA 98195-1700
Among all semiconducting nano-materials lead salts, such as PbS an PbSe, are supposed to have nearly symmetric conduction and valence bands at the direct gap. That corresponds to similar effective masses of electrons and holes, which significantly low Auger recombination rates. We have studied the strong confinement regime of phonon-induced carriers relaxation dynamics in PbSe quantum dots of 32 and 136 atoms with 0.09 and 0.13 nm in diameters. Our real time {\it ab initio} simulations, based on the non-adiabatic (NA) surface hopping technique implemented within time dependent density functional theory (TDDFT) demonstrate the relative similarities between relaxation mechanisms of electrons and holes, which has a large admixture of slow rate Gaussian components for both of carries. Despite the more discreet nature of energy levels of the small 32-atoms PbSe, we have observed the faster relaxation of populations of the initially exited states in a small quantum dot regarding a larger one, which can be explained by stronger confinement features in case of a small quantum dot.

Poster Session
7:30 PM-10:00 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster

8:00 PM-10:00 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Sci-Mix

Division of Physical Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006