Coulomb-blockade transport in quasi-one-dimensional polymer nanofibers

Abstract

We report the low temperature current-voltage (I-V) characteristics studies in quasi-one-dimensional conducting polymer nanofibers. We find a threshold voltage ${V}_{t}$ below which little current flows at temperatures below $30--40\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. For $V>{V}_{t}$ current scales as ${(V∕{V}_{t}\ensuremath{-}1)}^{\ensuremath{\zeta}}$ where $\ensuremath{\zeta}\ensuremath{\sim}1.8--2.1$ at high biases. Differential conductance oscillations are observed whose magnitude increases as temperature decreases below $10\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. We attributed the observed low temperature I-V behavior to Coulomb-blockade effects with a crossover to Luttinger liquidlike behavior at high temperature. We demonstrate that at low temperatures such a doped conjugated polymer fiber can be considered as an array of small conducting regions separated by nanoscale barriers, where the Coulomb-blockade tunneling is the dominant transport mechanism.