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Exploring the upper limit of single-walled carbon nanotube purity by multiple-cycle aqueous two-phase separation

Abstract

Ultrahigh purity semiconducting single-walled carbon nanotube (S-SWCNT) is required for high-performance transistors. Aqueous two-phase (ATP) separation is an attractive method to obtain such SWCNTs due to its simplicity and scalability. This work targeted two questions; namely what is the upper limit of S-SWCNT purity that can be achieved by multiple cycles of ATP separation from the most commonly used poly(ethyl glycol) and dextran system and how accurately can commonly use methods characterize the improvement in purity? SWCNT purity in nanotube dispersions obtained by multicycle ATP separation (2, 4, 6 and 8 cycles) was evaluated by three methods, including UV-vis-NIR absorption spectroscopy analysis, the performance of thin-film field effect transistors (FETs) prepared by drop casting and short-channel FET devices prepared by dielectrophoresis deposition. Absorption spectra analysis and performance of thin-film FET devices can hardly differentiate metallic SWCNT residues in dispersions obtained after 4 cycles with the purity above 99.5%, short channel FET devices prepared by dielectrophoresis deposition is more sensitive towards tiny metallic SWCNT residues. A new method was also demonstrated to visualize the minor metallic content in nanotube suspension using voltage contrast imaging in a scanning electron microscope, which enables rapid screening of many devices and the accurate obtainment of metallic content without performing large numbers of individual transconductance measurements.

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Publication details

The article was received on 10 May 2017, accepted on 12 Jul 2017 and first published on 14 Jul 2017


Article type: Paper
DOI: 10.1039/C7NR03302H
Citation: Nanoscale, 2017, Accepted Manuscript
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    Exploring the upper limit of single-walled carbon nanotube purity by multiple-cycle aqueous two-phase separation

    W. Li, B. S. Flavel, W. Li, R. Krupker and Y. Chen, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR03302H

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