Quantized exciton-exciton recombination in undoped and hole-doped single-walled carbon nanotubes

We studied the quantized exciton Auger recombination in undoped and hole-doped single-walled carbon nanotubes (SWCNTs) by means of transient absorption spectroscopy and theoretical calculations. In undoped SWCNTs, a fast decay component appears under strong photoexcitation owing to two-exciton Auger recombination. The exciton decay dynamics is well explained by the quantized exciton Auger recombination model that takes into consideration the dark-exciton state. In hole-doped SWCNTs, the fast decay component is drastically reduced even under strong photoexcitation. We calculated the temporal evolution of the exciton population in hole-doped samples by considering exciton-hole interactions and the hole-number distribution in SWCNTs, and found it to be in good agreement with the experimental results.