Highly Efficient Bilateral Doping of Single-Walled Carbon Nanotubes

TL;DR

This paper introduces a highly efficient bilateral doping method for single-walled carbon nanotubes, significantly improving their electrical conductivity while maintaining high transparency, advancing their application in flexible transparent conductive films.

Contribution

The study presents a novel bilateral doping technique for SWCNTs using chloroauric acid, achieving record low sheet resistance at high transmittance, confirmed by experimental and theoretical analyses.

Findings

Achieved sheet resistance of 31 Ω/sq at 90% transmittance

Confirmed strong p-doping via open-circuit potential measurements

Validated doping effects with ab initio calculations showing Fermi level downshift

Abstract

A boost in the development of flexible and wearable electronics facilitates the design of new materials to be applied as transparent conducting films (TCFs). Although single-walled carbon nanotube (SWCNT) films are the most promising candidates for flexible TCFs, they still do not meet optoelectronic requirements demanded their successful industrial integration. In this study, we proposed and thoroughly investigated a new approach that comprises simultaneous bilateral (outer and inner surfaces) SWCNT doping after their opening by thermal treatment at 400 C under an ambient air atmosphere. Doping by a chloroauric acid (HAuCl$_{4}$) ethanol solution allowed us to achieve the record value of sheet resistance of 31 $\pm$ 4 $\Omega$/sq at a transmittance of 90% in the middle of visible spectra (550 nm). The strong p-doping was examined by open-circuit potential (OCP) measurements and confirmed by ab initio calculations demonstrating a downshift of Fermi level around 1 eV for the case of bilateral doping.