Separation of Single Walled Carbon Nanotubes by Light

TL;DR

This study demonstrates optical methods using UV, visible, and NIR light to separate metallic and semiconducting single-walled carbon nanotubes based on their optical responses and diameters, verified by spectroscopy and electronic measurements.

Contribution

It introduces a novel optical separation technique for SWNTs that distinguishes metallic and semiconducting types by their optical aggregation behavior under different light frequencies.

Findings

UV light enriches metallic SWNTs in supernatant

Different diameters of SWNTs aggregate depending on illumination frequency

Optically separated SWNTs show expected electronic properties in FET tests

Abstract

We report optical separation of metallic and semiconducting single walled carbon nanotubes of specific diameters from well-dispersed, stable solution. This phenomenon of optical separation was studied using lamps of different frequencies across UV, Vis and NIR spectrum. Optically aggregated SWNTs were separated from the SWNTs remaining dispersed in the solution and characterized using absorption and Raman spectroscopy. Separated SWNTs distinctly show enrichment of metallic SWNTs using UV lamp, whereas different diameter of SWNTs aggregates out depending on the frequency of illumination. Fabricated field effect transistors based on the separated SWNTs under UV lamp confirms enrichment of metallic SWNTs in the supernatant where as aggregated SWNTs shows semiconducting behavior. Spectral changes and electronic (IV) measurements of our optically separated SWNTs were compared and verified with the reference solution of pre-separated, pure metallic and semiconducting SWNTs.