Ordered Semiconducting Nitrogen-Graphene Alloys

H J Xiang,Z Y Li,J L Yang,B Huang,S.-H Wei,X G Gong

doi:10.1103/physrevx.2.011003

H J Xiang, Z Y Li + Show 4 more

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https://doi.org/10.1103/physrevx.2.011003

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Abstract

The interaction between substitutional nitrogen atoms in graphene is studied by performing first principles calculations. The nearest neighbor interaction between nitrogen dopants is highly repulsive because of the strong electrostatic repulsion between nitrogen atoms, which prevents the full phase separation in nitrogen doped graphene. Interestingly, there are two relatively stable nitrogen-nitrogen pairs due to the anisotropy charge redistribution induced by nitrogen doping. We reveal two stable semiconducting ordered N doped graphene structures C3N and C12N through the cluster expansion technique and particle swarm optimization method. In particular, C12N has a direct band gap of 0.98 eV. The heterojunctions between C12N and graphene nanoribbons might be promising organic solar cells.

Highlights

Graphene, a single layer of carbon atoms arranged in a honeycomb lattice, has been a focus of recent research efforts [1,2,3] due to its unique semimetallic zero-gap electronic structure and the massless Dirac-fermion behavior
We find that the nearest-neighbor interaction between nitrogen dopants is highly repulsive as a result of the strong electrostatic repulsion between negatively charged nitrogen atoms
We propose that C12N=6-AGNR heterojunctions are a promising candidate for a new type of organic solar cell with C12N as a donor and 6-AGNR as an acceptor, respectively

Summary

Introduction

A single layer of carbon atoms arranged in a honeycomb lattice, has been a focus of recent research efforts [1,2,3] due to its unique semimetallic zero-gap electronic structure and the massless Dirac-fermion behavior. One is the substrate-induced gap for graphene supported on silicon carbide (SiC) [4], but the experimental realization of this idea turned out to be very difficult and controversial [5]. Another approach is the creation of gaps through confinement [6], such as in narrow graphene nanoribbons (GNRs). It has been demonstrated that the band gap of a graphene bilayer can be controlled externally by applying a gate bias [7,8]. Chemical functionalization [9,10] is an alternative way to manipulate the electronic properties of graphene.

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