2010/09/02 by Zhibin Lin, Alberto Franceschetti, Mark T. Lusk · 1 citation
Materials Science · Physics and Astronomy · #Chemical and Physical Properties of Materials #Coulomb #Electron #Exciton #Multiple exciton generation #Photon #Photon energy #Pseudopotential #Quantum Dots Synthesis And Properties #Quantum dot #Semiconductor Quantum Structures and Devices #Trion #cond-mat.mes-hall #cond-mat.mtrl-sci #physics.comp-ph #physics.optics
paper · pdf · doi:10.1021/nn200141f
published as ACS Nano 5 2503 2011 · 19 pages, 6 figures
arxiv created 2010/09/02 · openalex publication_date 2011/03/01 · arxiv updated 2015/05/13 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The multiplication rates of hot carriers in CdSe quantum dots are quantified using an atomistic pseudopotential approach and first-order perturbation theory. We consider both the case of an individual carrier (electron or hole) decaying into a trion and the case of an electron-hole pair decaying into a biexciton. The dependence on quantum dot volume of multiplication rate, density of final states, and effective Coulomb interaction are determined. We show that the multiplication rate of a photogenerated electron-hole pair decreases with dot size for a given absolute photon energy. However, if the photon energy is rescaled by the volume-dependent optical gap, then smaller dots exhibit an enhancement in carrier multiplication rate for a given relative photon energy. We find that holes have much higher multiplication rates than electrons of the same excess energy due to the larger density of final states (positive trions). When electron-hole pairs are generated by photon absorption, however, the net carrier multiplication rate is dominated by electrons because they have much higher excess energy on average. We also find, contrary to earlier studies, that the effective Coulomb coupling governing carrier multiplication is energy-dependent.