Application of Graphene-Based Transparent Conductors (TCs)

Abstract

As graphene has several potential advantages over indium tin oxide (ITO) including weight, robustness , flexibility, chemical stability, and cost, many applications, such as touch panels, displays, solar cells, organic light-emitting diode, transistors and other new areas, have been demonstrated [1]. Although the application of graphene for transparent conductors (TCs) is still in its early stage and the performances of some devices presented in this book are in a preoptimized state, the unique functional characteristics can make graphene a strong candidate to replace the currently commercially dominant TC materials [2]. These devices, with their functional, structural, and mechanical requirements, where graphene has been considered to apply are discussed in this chapter. Touch ScreenA touch screen is an electronic visual display that detects the presence and location of a touch [2]. A variety of touch-screen technologies, such as resistive, surface acoustic wave, capacitive, surface capacitance, projected capacitance, has been developed [3]. The most commonly used touch screens are the resistive and capacitive types, which require a sheet resistance of ~ 300-1500 Ω/sq at a transparency of ~ 86-90 % [4]. Graphene has several advantages including flexibility, wear resistance, chemical durability, and low toxicity (Fig. 5.1a-b) compared to the traditional ITO. Based on the successful fabrication of graphene films, with outstanding sheet resistance and transparency, and a large size of tens of centimeters, Bae et al.[5] incorporated them into touch-screen panel devices (Fig. 5.1b). It is revealed that the touch-screen display made from graphene outperformed that of ITO in terms of the applied strain. The former touch screen could handle twice as much strain as conventional ITO-based devices (Fig. 5.1c) [5]. The graphene-based panel resisted up to 6 % strain, which is limited mainly by the silver electrode and not by graphene itself, while the ITO-based touch panel easily broke at just 2-3 % strain.