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

TL;DR

This paper reports on a novel optically active nanotube-hybrid material where UV light induces a charge redistribution via chromophore isomerization, modulating the electrical properties of single-wall carbon nanotubes for potential nano-photodetector applications.

Contribution

It introduces a new method of functionalizing carbon nanotubes with azo-based chromophores to achieve reversible optical modulation of their electrical conductance.

Findings

UV illumination causes a 1.2 V shift in threshold voltage.

Conductance change is reversible and stable over time.

Functionalized nanotubes can be used for nano-photodetectors.

Abstract

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 ~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 nano-photodetectors.