PNNL

Abstract

Control of the conductivity of single wall carbon nanotubes (SWNTs) is crucial for the use of carbon nanotubes in molecular electronics. We report a new fundamental characteristic of semiconducting SWNTs – the persistent photoconductivity of chemically-modified carbon nanotube films. Covalent attachment of Ruthenium(II)-tris(2,2’-bipyridine) Ru(bpy) ²?/3 to SWNT makes carbon nanotubes sensitive to light absorbed by the ruthenium complex and persistently photoconductive, thus opening opportunities for the selective light control of the conductivity. Illumination of carboxylated SWNTs with ultraviolet or visible light causes a persistent decrease in the conductivity of semiconducting films. Infrared illumination restores conductivity of SWNT films.