Separation of Metallic and Semiconducting Single-Wall Carbon Nanotube Solution by Vertical Electric Field

Abstract

A novel method to separate metallic and semiconducting single-wall carbon nanotubes (SWCNTs) by free solution electrophoresis was investigated. A vertical electrophoretic cell was used to separate SWCNT aqueous solution by the application of electric field along the vertical cell. In contrast with conventional electrophoresis, electric-field-induced layer formation was found in the cell with clear horizontal boundaries. Both the optical absorbance spectra and resonant Raman spectra of these layers revealed the enrichment of metallic and semiconducting SWCNTs with 95% semiconducting SWCNTs in a layer. This method was successfully applied for SWCNTs with diameters from 1.0 to 1.7 nm. Thin-film transistors fabricated by the direct deposition of the semiconductor-enriched nanotubes onto the substrate showed excellent transport properties with an on/off current ratio of 4.4 × 10 5 and a mobility of 6.8 cm 2 V –1 s –1 .