title: Theoretical predictions on efficiency of bi-exciton formation and dissociation in chiral carbon nanotubes.
abstract: Efficient multiple exciton generation (MEG) in chiral single-wall carbon nanotubes (SWCNTs) is present within the solar spectrum range as shown by the many-body perturbation theory calculations combined with the density functional theory simulations. To describe the impact ionization process, we calculate exciton-to-biexciton decay rates R1→2and biexciton-to-exciton rates R2→1in the (6,2) and (10,5) SWCNTs. Within the solar energy range, we predict R1→2∼ 1014s-1, while biexciton-to-exciton recombination is weak with R2→1/R1→2≤ 10-2. Also we calculate quantum efficiency (QE), the average number of excitons created by a single absorbed photon, for which we find QE ≃ 1.2-1.6, that is 20%-60%. However, MEG strength in these SWCNTs varies strongly with the excitation energy due to highly non-uniform density of states at the low energy. We hypothesize that MEG efficiency in the chiral SWCNTs can be enhanced by altering the low-energy electronic spectrum via surface functionalization, or by mixing SWCNTs of different chiralities.
authors: Department of Physics, North Dakota State University, Fargo, North Dakota 58108, USA.
authors: Andrei
authors: A
authors: Kryjevski
authors: Department of Chemistry, North Dakota State University, Fargo, North Dakota 58108, USA.
authors: Brendan
authors: B
authors: Gifford
authors: Department of Chemistry, North Dakota State University, Fargo, North Dakota 58108, USA.
authors: Svetlana
authors: S
authors: Kilina
authors: Department of Chemistry, North Dakota State University, Fargo, North Dakota 58108, USA.
authors: Dmitri
authors: D
authors: Kilin