Mechanism of Electrolyte-Induced Brightening in Single-Wall
Carbon Nanotubes
- Publication date
- Publisher
Abstract
While
addition of electrolyte to sodium dodecyl sulfate suspensions
of single-wall carbon nanotubes has been demonstrated to result in
significant brightening of the nanotube photoluminescence (PL), the
brightening mechanism has remained unresolved. Here, we probe this
mechanism using time-resolved PL decay measurements. We find that
PL decay times increase by a factor of 2 on addition of CsCl as the
electrolyte. Such an increase directly parallels an observed near-doubling
of PL intensity, indicating the brightening results primarily from
changes in nonradiative decay rates associated with exciton diffusion
to quenching sites. Our findings indicate that a reduced number of
these sites results from electrolyte-induced reorientation of the
surfactant surface structure that partially removes pockets of water
from the tube surface where excitons can dissociate, and thus underscores
the contribution of interfacial water in exciton recombination processes