Research Article Physical Properties Investigation of Reduced Graphene Oxide Thin Films Prepared by Material Inkjet Printing Veronika Schmiedova, 1 Jan Pospisil, 1 Alexander Kovalenko, 1 Petr Ashcheulov, 2 Ladislav Fekete, 2 Tomas Cubon, 1 Peter Kotrusz, 3 Oldrich Zmeskal, 1 and Martin Weiter 1 1 Faculty of Chemistry, Brno University of Technology, Purkynova 118, 612 00 Brno, Czech Republic 2 Institute of Physics, Academy of Sciences Czech Republic v. v. i., Na Slovance 2, 182 21 Prague 8, Czech Republic 3 Danubia NanoTech, s.r.o., Ilkovicova 3, 841 04 Bratislava, Slovakia Correspondence should be addressed to Veronika Schmiedova; xcschmiedova@fch.vut.cz Received 23 March 2017; Revised 12 July 2017; Accepted 19 July 2017; Published 23 August 2017 Academic Editor: Zainovia Lockman Copyright © 2017 Veronika Schmiedova et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Te 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 fexible 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. Te thicknesses of the layers were determined by a mechanical proflometer and used as an input parameter for optical modeling. Ellipsometric spectra were analyzed according to the dispersion model and the infuence of the reduction of GO on optical constants is discussed. Tus, detailed analysis of the ellipsometric data provides a unique tool for qualitative and also quantitative description of the optical properties of GO thin flms for electronic applications. 1. Introduction Graphene is a two-dimensional (2D) carbon-based material [1], which has recently attracted particular attention due to its specifc electronic structure [2], which gives it unusual electronic properties such as the anomalous quantum Hall efect [3, 4] and startling high carrier mobility at relatively high charge carrier concentrations [5]. Tis material was frst isolated in 2003 [6] and immediately became a potential candidate for electronic applications [7]. Recently, it was shown [8] that graphene also provides extraordinary optical properties. Graphene absorbs a 2.3% fraction of incident white light, and due to this graphene provides unique elec- tronic properties and structure [9, 10]. However, graphene sheets have limited practical application due to the fact that graphene is insoluble and infusible. 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). Graphene oxide (GO) is an atomically thin carbon nanos- tructure with various oxygen-containing functional moieties such as carbonyl, carboxyl, and hydroxyl (Figure 1). GO and rGO have attracted a great deal of attention due to their remarkable physical, chemical, and mechanical properties and could be used as a potential novel electronic material [13– 15]. Graphene oxide is potentially usable due to its sim- ple synthesis and processing [12]. Te presence of oxygen functional groups leads to dispersibility in water and other organic solvents [16]. Tis remains a very important feature for improving their properties of the material with polymer matrixes such as electrical and mechanical characterization. From previous studies in the literature [17], it is known that in graphene one absorbed photon is capable of producing many excited electrons (in traditional materials, energy from one photon only excites one electron) and is therefore able Hindawi Journal of Nanomaterials Volume 2017, Article ID 3501903, 8 pages https://doi.org/10.1155/2017/3501903