Optically Modulated Conduction in Chromophore-Functionalized Single-Wall Carbon Nanotubes

We demonstrate an optically active nanotube-hybrid material by functionalizing single-wall nanotubes with an azo-based chromophore. Upon UV illumination, the conjugated chromophore undergoes a cis-trans isomerization leading to a charge redistribution near the nanotube. This charge redistribution changes the local electrostatic environment, shifting the threshold voltage and increasing the conductivity of the nanotube transistor. For a approximately 1%-2% coverage, we measure a shift in the threshold voltage of up to 1.2 V. Further, the conductance change is reversible and repeatable over long periods of time, indicating that the chromophore-functionalized nanotubes are useful for integrated nanophotodetectors.