Temperature dependence of mobility of conducting polymer polyaniline with secondary dopant

TL;DR

This study investigates how secondary doping with meta-cresol affects the electrical conductivity and mobility of polyaniline, revealing that conductivity varies significantly with doping while mobility's temperature dependence aligns with polaron hopping models.

Contribution

It provides new insights into the temperature-dependent mobility of polyaniline influenced by secondary doping and supports the polaron hopping model as an explanation.

Findings

Conductivity varies by four orders of magnitude with doping concentration.

Carrier density shows weak dependence on doping within certain ranges.

Mobility temperature dependence is well explained by the polaron hopping model.

Abstract

The conductivity $\sigma$ and carrier density $n$ of the conducting polymer polyaniline were investigated by changing the concentration $x$ of a secondary dopant, meta-cresol. We found that $\sigma$ changes by four orders of magnitude within the $x$-range of 1-10 %, while $n$, as estimated from the Hall measurements, shows a weak dependence on $x$ in the region of 2% <$x$< 50%. These results suggest that $\sigma$ can be enhanced by the change in the mobility $\mu$. We analyzed the temperature dependence of $\mu$ by not only the combination of two different types of scattering mechanism, but also by the polaron hopping model. The experimental data of $\mu(T)$ can be explained well by the latter model with reasonable fitting parameter values of a small-polaron binding energy and a longitudinal optical phonon frequency.