The dynamics of lowest-energy E11 excitons in undoped and hole-doped single-walled carbon nanotubes (SWCNTs) are investigated using transient absorption spectroscopy and theoretical calculations. In undoped SWCNT samples, E11 excitons under resonant E11 photoexcitation show faster decay than those under high-energy nonresonant photoexcitation. Doping SWCNTs with holes accelerates the E11 exciton decay through exciton-hole interactions; moreover, both resonant and nonresonant photoexcitation in hole-doped SWCNTs lead to nearly identical decay profiles. Theoretical calculations, which are based on a simple model that accounts for bright, dark, and charged exciton states, agree well with the experimental results. We ascribe the fast E11 exciton decay under the resonant E11 photoexcitation to the redistribution of exciton populations in the E11 bright exciton band, which includes optically accessible and inaccessible states; the rapid exciton redistribution is caused by exciton-hole scattering. Our study provides a clear understanding of the global features of exciton dynamics in SWCNTs.
ASJC Scopus subject areas