Structural and Electronic Properties of Graphdiyne Carbon Nanotubes from Large-Scale DFT Calculations

TL;DR

This study uses large-scale DFT calculations to analyze the structural stability and electronic properties of graphdiyne nanotubes, providing new insights into their size-dependent bandgaps and mobility differences based on chirality.

Contribution

It presents the first large-scale DFT analysis of the largest graphdiyne nanotubes, offering analytical formulas for bandgap estimation and comparing stability and electronic properties by chirality.

Findings

Zigzag GDNTs are more stable than armchair GDNTs.

Bandgaps can be tuned by size and chirality.

Zigzag GDNTs likely have higher mobility than armchair GDNTs.

Abstract

Using large-scale DFT calculations, we have investigated the structural and electronic properties of both armchair and zigzag graphdiyne nanotubes as a function of size. To provide insight in these properties, we present new detailed calculations of the structural relaxation energy, effective electron/hole mass, and size-scaling of the bandgap as a function of size and chirality using accurate screened-exchange DFT calculations. These calculations provide a systematic evaluation of the structural and electronic properties of the largest graphdiyne nanotubes to date - up to 1,296 atoms and 23,328 basis functions. Our calculations find that zigzag graphdiyne nanotubes (GDNTs) are structurally more stable compared to armchair GDNTs of the same size. Furthermore, these large-scale calculations allow us to present simple analytical formulae to guide future experimental efforts for estimating the fundamental bandgaps of these unique nanotubes as a function of chirality and diameter. While the bandgaps for both the armchair and zigzag GDNTs can be tuned as a function of size, the conductivity in each of these two different chiralities is markedly different. Zigzag GDNTs have wider valence and conduction bands and are expected to have a higher electron- and hole-mobility than their armchair counterparts.