The current standard material used for transparent electrodes in displays, touch screens and solar cells is indium tin oxide (ITO) which has low sheet resistance (10 Ω/□), high optical transmission in the visible wavelength (85%) and does not suffer of optical haze. However, ITO is mechanically rigid and incompatible with future demands for flexible applications. Graphene materials share many of the properties desirable for flexible transparent conductors, including high optical transparency, high mechanical flexibility and strength. Whilst pristine graphene is not a good transparent conductor, functionalised graphene is at least 1000 times a better conductor than its pristine counterpart and it outperforms ITO. Here the authors review recent work on a novel graphene-based conductor with sheet resistance as low as 8.8 Ω/□ and 84% optical transmission. This material is obtained by ferric chloride (FeCl3) intercalation into few-layer-graphene (FLG), giving rise to a new system which is the best known flexible and transparent electricity conductor. FeCl3-FLG shows no significant changes in the electrical and structural properties for a long exposure to air, to high levels of humidity and at temperatures of up to 150°C in atmosphere. These properties position FeCl3-FLG as a viable and attractive replacement to ITO.
['Thomas H. Bointon', 'Saverio Russo', 'Monica F. Craciun']
Is graphene a good transparent electrode for photovoltaics and display applications