Transport modulation of graphene nanoribbons with side-attached organic molecules

TL;DR

This study investigates how attaching organic molecules to graphene nanoribbons influences their conductance, revealing length-dependent spectral features and parity effects, with potential applications in spectrograph-sensor devices.

Contribution

It demonstrates the modulation of GNR conductance by side-attached organic molecules and identifies parity effects related to molecular length, using a tight-binding and Green's function approach.

Findings

Conductance varies with organic molecule length.

Spectral features are reflected in conductance curves.

Parity effects influence conductance based on molecule length.

Abstract

In this work we address the effects on the conductance of graphene nanoribbons (GNRs) at which organic molecules are side-attached on the ribbon ends. For simplicity, only armchair (AGNRs) and zigzag (ZGNRs) nanoribbons are considered and quasi one-dimensional molecules, such as linear poly-aromatic hydrocarbon (LPHC) and poly(para-phenylene), are chosen. The conductance of the GNRs exhibit a particular behavior as a function of the length of the organic molecules: the energy spectrum of the quasi one-dimensional system is clearly reflected in the conductance curves of the GNRs. The results suggest that GNRs can be used as an spectrograph-sensor device. An even-odd parity effect, as a function of the length of the attached molecules, can be observed in the conductance of these system. The nanostructures are described using a single-band tight binding Hamiltonian and the electronic conductance and the density of states of the systems are calculated within the Green's function formalism based on real-space renormalization techniques.