Bundle vs. network conductivity of carbon nanotubes separated by type

TL;DR

This study compares the optical and transport properties of separated semiconducting and metallic carbon nanotube networks, revealing that intrinsic nanotube conductivity significantly influences overall network performance and doping effects.

Contribution

It provides a comprehensive analysis of how nanotube type and doping affect the conductivity and transparency of carbon nanotube networks, highlighting the importance of intrinsic properties over contact effects.

Findings

Higher intrinsic nanotube conductivity improves network transport properties.

HNO3 doping enhances the transparent conductive quality more than separation.

Doped metallic nanotube films exhibit spontaneous dedoping within 24 hours.

Abstract

We report wide-range optical investigations on transparent conducting networks made from separated (semiconducting, metallic) and reference (mixed) single-walled carbon nanotubes, complemented by transport measurements. Comparing the intrinsic frequency-dependent conductivity of the nanotubes with that of the networks, we conclude that higher intrinsic conductivity results in better transport properties, indicating that the properties of the nanotubes are at least as much important as the contacts. We find that HNO3 doping offers a larger improvement in transparent conductive quality than separation. Spontaneous dedoping occurs in all samples but is most effective in films made of doped metallic tubes, where the sheet conductance returns close to its original value within 24 hours.