Mono- and Biexponential Luminescence Decays of Individual Single-Walled Carbon Nanotubes

We have studied the exciton recombination dynamics of individual (6,4) and (6,5) single-walled carbon nanotubes embedded in aqueous gels or deposited on glass surfaces. CoMoCat nanotubes systematically display short monoexponential photoluminescence (PL) decays presumably due to defects introduced during their synthesis. In contrast HiPco nanotubes can either display mono- or biexponential PL decays depending on the environmental conditions. Transition from bi- to monoexponential decays can be reproduced by a simple three level model taking into account defect-dependent nonradiative decay mechanisms.