Atomically resolved orientational ordering of C60 molecules on epitaxial graphene on Cu(111).

Minbok Jung,Dongbin Shin,Hyung-Joon Shin,So-Dam Sohn,Soon-Yong Kwon,Noejung Park

doi:10.1039/c4nr03249g

Minbok Jung, Dongbin Shin + Show 4 more

Open Access

https://doi.org/10.1039/c4nr03249g

Copy DOI

Abstract

A detailed understanding of interactions between molecules and graphene is one of the key issues for tailoring the properties of graphene-based molecular devices, because the electronic and structural properties of molecular layers on surfaces are determined by intermolecular and molecule-substrate interactions. Here, we present the atomically resolved experimental measurements of the self-assembled fullerene molecules on single-layer graphene on Cu(111). Fullerene molecules form a (4 × 4) superstructure on graphene/Cu(111), revealing only single molecular orientation. We can resolve the exact adsorption site and the configuration of fullerene by means of low-temperature scanning tunnelling microscopy (LT-STM) and density functional theory (DFT) calculations. The adsorption orientation can be explained in terms of the competition between intermolecular interactions and molecule-substrate interactions, where strong Coulomb interactions among the fullerenes determine the in-plane orientation of the fullerene. Our results provide important implications for developing carbon-based organic devices using a graphene template in the future.

Highlights

Since the discovery of graphene, carbon-based materials including other types of carbon allotropes such as fullerene (C60) and one-dimensional carbon nanotubes (CNTs) have attracted much attention due to their distinctive electronic and physical properties as well as their potential for use as building blocks for molecular electronic devices.[1,2,3,4] The scale of electronic components continues to shrink to the point that it is on the scale of a few tens of nanometres
We expect that electronic devices on such a scale can be realized with molecular components and this encourages research leading to a greater understanding of the fundamentals of molecular systems
We report a low-temperature scanning tunnelling microscopy (STM) study of selfassembled fullerene molecules on graphene/Cu(111) combined with rst-principles density functional theory (DFT) calculations

Summary

Introduction

Since the discovery of graphene, carbon-based materials including other types of carbon allotropes such as fullerene (C60) and one-dimensional carbon nanotubes (CNTs) have attracted much attention due to their distinctive electronic and physical properties as well as their potential for use as building blocks for molecular electronic devices.[1,2,3,4] The scale of electronic components continues to shrink to the point that it is on the scale of a few tens of nanometres. We report a low-temperature scanning tunnelling microscopy (STM) study of selfassembled fullerene molecules on graphene/Cu(111) combined with rst-principles density functional theory (DFT) calculations. By preparing sub-monolayer C60 molecules on graphene/Cu(111), we can successfully resolve the exact adsorption site and orientation of individual fullerenes by means of STM. We nd that the C60–C60 Coulomb interaction and the C60–graphene interaction play important roles in determining the con guration of selfassembled fullerenes

Methods

Results

Conclusion