Theoretical studies on architectures of straight Zigzag//Armchair carbon nanotube junctions as molecular electronic devices

Abstract

The intramolecular junctions of single-wall carbon nanotube (SWCNT), by various topological interfacial defects, have been theoretically investigated the geometric, electronic and rectifying properties. The interface geometries of junction were modeled by fusing the helical type varieties of zigzag and armchair tubes together via pentagon/heptagon (5/7) pair defects. The formation energy revealed an exothermic with the variation of nanotubes' diameter and chiralities. The electronic structures are dependent on the variation of tube's helicity and length. HOMO and LUMO states, particularly, exhibit an induction of even-odd "quantum size" oscillation since interfacial topologies have been changed through nanotubes' chiralities, like zigzag//zigzag and T-shapes junctions. The aspect of molecular rectification occurred on an even numbers of m in zigzag (m,0) segments at interfacial junctions. Such helical tubes, in which the total molecular charge is zero, have a significant ability to increase the potential barrier across molecular junction due to the topological 5/7 defects around the tube circumference. The objective of this study is to extend the understanding of the inherent relationship between geometrical and electronic properties of intramolecular junctions for molecular electronic devices that are made up of carbon nanotubes. © 2012 by Pan Stanford Publishing Pte. Ltd. All rights reserved.