Improving the Electrical Conductivity of Carbon Nanotube Networks: A First-Principles Study

Abstract

We address the issue of the low electrical conductivity observed in carbon nanotube networks using first-principles calculations of the structure, stability, and ballistic transport of different nanotube junctions. We first study covalent linkers, using the nitrene-pyrazine case as a model for conductance-preserving [2 + 1] cycloadditions, and discuss the reasons for their poor performance. We then characterize the role of transition-metal adsorbates in improving mechanical coupling and electrical tunneling between the tubes. We show that the strong hybridization between the transition-metal d orbitals with the π orbitals of the nanotube can provide an excellent electrical bridge for nanotube-nanotube junctions. This effect is maximized in the case of nitrogen-doped nanotubes, thanks to the strong mechanical coupling between the tubes mediated by a single transition metal adatom. Our results suggest effective strategies to optimize the performance of carbon nanotube networks.

Enhancing conductivity of metallic carbon nanotube networks by transition metal adsorption

“…Considering the electron densities of the OHEE 2 and OHEE 3 , orbitals of both CNTs hybridize strongly with the Cr atom orbitals. A similar coupling between the carbon π orbitals and d orbitals of the Cr atom has been seen in a system consisting of two polyacene molecules connected by one Cr atom, 29 which explains the good conductivity of the system. The OHEE 2 and OHEE 3 orbitals contain four small longitudinal regions that extend from one CNT to the other.…”

“…29, where the transmission peaks are significantly broader and the transmission is larger in magnitude. The broad transmission peaks of Ref.…”

“…In a recent study, DFT calculations have shown that the electronic transport through a junction consisting of two parallel semi-infinite (5,5) CNTs can be improved by linking the CNTs with a metal atom. 29 In this article, we consider a CNT junction where two metallic perpendicular and infinite CNTs are connected by a group 6 TM atom. Other TM atoms have not been considered because in the CNT junction they do not result in a stable closed-shell structure and the electron transport mechanism is expected to be remarkably different.…”

Stabilizing graphene-based organometallic sandwich structures through defect engineering

“…For example, one can form sandwich structures by stacking layers of graphene sheets (or graphene and other low dimensional graphitic structures) with the transition metal atom(s) incorporated between them. In such complexes, the metal atoms may be used to dope the constituents, and/or to provide electrical tunneling between different layers [47]. Although predicted to form theoretically, it is hard to create these sandwich structures experimentally.…”

First-principles quantum transport with electron-vibration interactions: A maximally localized Wannier functions approach

“…Since the Wannier transformation is an exact unitary mapping, one can construct a minimal set of atomic-like localized functions within an energy window of interest without losing the accuray of planewave-based DFT calculations, and a MLWF approach to quantum transport has been very successfully applied to zero-bias quantum conductance calculations 22,23 . The next step to develop a MLWF approach to quantum transport [22][23][24][25] is to include interaction effects on transport properties. In this paper we focus on extending MLWF-based ab initio quantum transport calculations to investigate electron-vibration interaction effects on molecular junctions.…”