The functional form of the photoluminescence (PL) line shape from individual single-walled carbon nanotube (SWNT) species is found to contain a significant Lorentzian component and the Stokes shift is observed to be very small (<8 meV), which suggests an excitonic dephasing mechanism that is largely decoupled from surrounding solvent and surfactant molecules. The PL quantum yield (PLQY) of two SWNT species is determined to be ∼5×10 -4, and it is suggested that this is lower than the "true" value due to quenching of the PL in bundles by metallic tubes. Time-resolved PL measurements reveal a dominant, luminescence lifetime component of 130 ps that, when combined with a predicted natural radiative lifetime of ∼20 ns, suggests that the true PLQY is ∼6.5×10 -3. Finally, deconvoluted PL excitation spectra are produced for eight SWNT species, and the appearance of a higher-energy excitonic subband is discussed.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Mar 15 2005|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics