Diffusion Limited Photoluminescence Quantum Yields in 1-D Semiconductors: Single-Wall Carbon Nanotubes

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• 作者：Tobias Hertel ; Sabine Himmelein ; Thomas Ackermann ; Dominik Stich ; Jared Crochet
• 刊名：ACS Nano
• 出版年：2010
• 出版时间：December 28, 2010
• 年：2010
• 卷：4
• 期：12
• 页码：7161-7168
• 全文大小：397K
• 年卷期：0
• ISSN：1936-086X

文摘

Photoluminescence quantum yields and nonradiative decay of the excitonic S₁ 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 cm²s⁻¹ and lifetime τ_PL for long tubes of 20 ± 1 ps. PL quantum yields Φ_PL are found to scale with the inverse diffusion coefficient and the square of the mean quenching site distance, here l_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.