Electro-optical interfacial effects on a graphene/π-conjugated organic semiconductor hybrid system.

Karolline A S Araujo,Luiz G Cançado,Thales F D Fernandes,Luiz A Cury,Bernardo R A Neves,Matheus J S Matos

doi:10.3762/bjnano.9.90

Karolline A S Araujo, Luiz G Cançado + Show 4 more

Open Access

https://doi.org/10.3762/bjnano.9.90

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Abstract

The influence of graphene and retinoic acid (RA) – a π-conjugated organic semiconductor – interface on their hybrid system is investigated. The physical properties of the interface are assessed via scanning probe microscopy, optical spectroscopy (photoluminescence and Raman) and ab initio calculations. The graphene/RA interaction induces the formation of a well-organized π-conjugated self-assembled monolayer (SAM) at the interface. Such structural organization leads to the high optical emission efficiency of the RA SAM, even at room temperature. Additionally, photo-assisted electrical force microscopy, photo-assisted scanning Kelvin probe microscopy and Raman spectroscopy indicate a RA-induced graphene doping and photo-charge generation. Finally, the optical excitation of the RA monolayer generates surface potential changes on the hybrid system. In summary, interface-induced organized structures atop 2D materials may have an important impact on both design and operation of π-conjugated nanomaterial-based hybrid systems.

Highlights

Organic semiconductors offer a wide range of possible applications, from thin-film transistors to sensors and solar cells [1,2,3,4,5,6]
Since the adsorbing species interaction with monolayer graphene can be largely influenced by the underlying substrate [17,18], we expect that graphite microplates would screen any spurious influence of a given supporting substrate on the adsorbing retinoic acid (RA) molecule
We expect that a graphite flake, rather than monolayer graphene on a Si/silicon oxide (SiOx) substrate, for example, should enable a true RA/graphene interfacial interaction, free from deleterious influence of the supporting substrate

Summary

Introduction

Organic semiconductors offer a wide range of possible applications, from thin-film transistors to sensors and solar cells [1,2,3,4,5,6] Their optical and electronic properties are strongly linked to intermolecular interaction parameters associated with molecular packing and/or ordering [7]. Previous works have demonstrated that intermolecular interactions can dramatically reduce the luminescence quantum yield in solid-state devices [8,9,10,11,12,13] In this context, it is important to control the ordering of π-conjugated organic molecules to make their use on optoelectronic devices possible.

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