Multiexciton Generation in IV-VI Nanocrystals: The Role of Carrier Effective Mass, Band Mixing, and Phonon Emission.
We study the role of the effective mass, band mixing, and phonon emission on multiexciton generation in IV-VI nanocrystals. A four-band k · p effective mass model, which allows for an independent variation of these parameters, is adopted to describe the electronic structure of the nanocrystals. Multiexciton generation efficiencies are calculated using a Green's function formalism, providing results that are numerically similar to impact excitation. We find that multiexciton generation efficiencies are maximized when the effective mass of the electron and hole are small and similar. Contact with recent experimental results for multiexciton generation in PbS and PbSe is made.
Gal
G
Zohar
‡Fritz Haber Center for Molecular Dynamics, Institute of Chemistry, Hebrew University, Jerusalem 91904, Israel.
Roi
R
Baer
Eran
E
Rabani
dynamics; excitons; hot carriers; solar cells; theory