Article,
Diffusion Limited Photoluminescence Quantum Yields in 1-D Semiconductors: Single-Wall Carbon Nanotubes
ACS NANO, 4 (12): 7161-7168 (December 2010)
DOI: {10.1021/nn101612b}
Abstract
Photoluminescence quantum yields and nonradiative decay of the excitonic
S-1, state in length fractionated (6,5) single-wall carbon nanotubes
(SWNTs) are studied by continuous wave and time-resolved fluorescence
spectroscopy. The experimental data are modeled by diffusion limited
contact quenching of excitons at stationary quenching sites including
tube ends. A combined analysis of the time-resolved photoluminescence
decay and the length dependence of photoluminescence quantum yields (PL
QYs) from SWNTs in sodium cholate suspensions allows to determine the
exciton diffusion coefficient D = 10.7 +/- 0.4 cm(2)s(-1) and lifetime
T-pL for long tubes of 20 +/- 1 ps. PL quantum yields Phi(pL) are found
to scale with the inverse diffusion coefficient and the square of the
mean quenching site distance, here I-d = 120 +/- 25 nm. The results
suggest that low PL QYs of SWNTs are due to the combination of
high-diffusive exciton mobility with the presence of only a few
quenching sites.
