Physical Properties Investigation of Reduced Graphene Oxide Thin Films Prepared by Material Inkjet Printing

Veronika Schmiedova,Peter Kotrusz,Ladislav Fekete,Alexander Kovalenko,Tomas Cubon,Martin Weiter,Oldrich Zmeskal,Petr Ashcheulov,Jan Pospisil

doi:10.1155/2017/3501903

Abstract

The article is focused on the study of the optical properties of inkjet-printed graphene oxide (GO) layers by spectroscopic ellipsometry. Due to its unique optical and electrical properties, GO can be used as, for example, a transparent and flexible electrode material in organic and printed electronics. Spectroscopic ellipsometry was used to characterize the optical response of the GO layer and its reduced form (rGO, obtainable, for example, by reduction of prepared layers by either annealing, UV radiation, or chemical reduction) in the visible range. The thicknesses of the layers were determined by a mechanical profilometer and used as an input parameter for optical modeling. Ellipsometric spectra were analyzed according to the dispersion model and the influence of the reduction of GO on optical constants is discussed. Thus, detailed analysis of the ellipsometric data provides a unique tool for qualitative and also quantitative description of the optical properties of GO thin films for electronic applications.

Highlights

Graphene is a two-dimensional (2D) carbon-based material [1], which has recently attracted particular attention due to its specific electronic structure [2], which gives it unusual electronic properties such as the anomalous quantum Hall effect [3, 4] and startling high carrier mobility at relatively high charge carrier concentrations [5]
It was found that thermal reduction is probably the best way of reducing graphene oxide (GO) while UV reduction and chemical reduction result in more defects in the GO/reduced graphene oxide (rGO) structure, which was confirmed by Raman measurements
Roughness was in the range of 2-3 nm for nonreduced and reduced samples, but the roughness strongly depends on the thickness of the samples

Summary

Introduction

Graphene is a two-dimensional (2D) carbon-based material [1], which has recently attracted particular attention due to its specific electronic structure [2], which gives it unusual electronic properties such as the anomalous quantum Hall effect [3, 4] and startling high carrier mobility at relatively high charge carrier concentrations [5]. This material was first isolated in 2003 [6] and immediately became a potential candidate for electronic applications [7]. Recent reports suggest that solution-processable graphene oxides (GOs), resulting from exfoliation of graphite powders with strong oxidizing reagents [11, 12], can be deposited by wet processing with a consequent reduction to a so-called reduced graphene oxide (rGO)

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