Helicity-selective photoreaction of single-walled carbon nanotubes with organosulfur compounds in the presence of oxygen.

This report describes a helicity-selective photoreaction of single-walled carbon nanotubes (SWNTs) with disulfide in the presence of oxygen. The SWNTs were characterized using absorption, photoluminescence (PL), Raman, and X-ray photoelectron spectroscopy, scanning electron microscopy, and current-voltage (I-V) measurements. Results showed remarkable helicity-selective (metallic SWNTs/semiconducting SWNTs and diameter) functionalization of SWNTs. The reaction rate decreases in the order of metallic SWNTs > semiconducting SWNTs and small-diameter SWNTs > large-diameter SWNTs. Control experiments conducted under various experimental conditions and ESR and femtosecond laser flash photolysis measurements revealed that the helicity-selective reaction proceeds via a photoinduced electron transfer reaction. The PL and I-V measurements showed that the photoreaction is effective not only to control SWNT conductivity but also for the band gap modulation of semiconducting SWNTs.

Preparation and characterization of transparent and conductive thin films of single-walled carbon nanotubes.

Single-walled carbon nanotubes (SWNTs), synthesized using the arc-discharge method and the direct-injection-pyrolytic synthesis (DIPS) method, were dispersed in a tetrahydrofuran solution containing propylamine and used to prepare transparent and conductive thin films on PET films using an airbrush technique. The SWNTs were analyzed using vis-near infrared absorption spectroscopy, Raman spectroscopy, scanning electron microscopy, and atomic force microscopy. The surface resistivity of the SWNT films on the substrates was measured using a four-point probe conductivity measurement. The results revealed that the purity, length, and proportion of the metallic SWNTs are important factors in decreasing the sheet resistance.