(439d) Tuning the Bandgap of Graphene Nanoribbons through Defect-Interaction-Driven Edge Patterning
AIChE Annual Meeting
2017
2017 Annual Meeting
Materials Engineering and Sciences Division
Nanoelectronic and Photonic Materials II: 2D Materials
Tuesday, October 31, 2017 - 4:03pm to 4:19pm
In this presentation, we report a defect engineering strategy for tuning the bandgap of GNRs based on patterning of the GNR edges. The defects of interest are nanopores, or vacancy clusters, which can be introduced into GNRs in regular arrangements by ion etching or electron irradiation. We have conducted a systematic analysis of pore-edge interactions in GNRs using molecular-statics computations based on reliable interatomic potentials, which have revealed strongly attractive interactions for nanopores in the vicinity of GNR edges. These attractive interactions provide the thermodynamic driving force for nanopore migration toward the GNR edge, leading to its coalescence with the GNR edge through a sequence of carbon ring reconstructions. We have studied nanopore dynamics near GNR edges in detail through molecular-dynamics (MD) simulations at high temperature. We have constructed the optimal kinetic pathways of the mechanisms mediating the coalescence of the nanopore and the GNR edge, as identified by the MD simulations, using climbing-image nudged elastic band calculations. We have found that the post-coalescence morphological evolution of an armchair GNR edge leads to the formation of a V-shaped edge pattern consisting of zigzag linear segments (facets). First-principles calculations of the electronic band structure of such patterned GNRs based on density functional theory show that the zigzag segments formed at the armchair edges can be used to tune the bandgap of the GNR. We find a linear dependence of the bandgap of the patterned GNRs on the linear density of the zigzag edge atoms, which is controlled by the size and concentration of the pores introduced in the defect-engineered GNR.