Controlled synthesis of nanocrystalline glass-like carbon thin films with tuneable electrical and optical properties

Graphene is an emerging electronic material but expensive and difficult to produce in pure, large-area thin films. Organic electronic applications such as flexible devices and energy applications would benefit from low-cost alternatives to graphene. The controlled synthesis of nanometer-thin carbon films by atmospheric pressure chemical vapor deposition on copper foils is presented. These nanostructured carbon thin films (5-237 nm of thickness) are composed of curved graphene fullerene-like fragments of ca. 3 nm average size, which replicate the structure of widely used glass-like carbons. The optical and electrical properties of these nanostructured carbon thin films are defined by the thickness of these films; high transparency (86%) and moderate high electrical conductivity (7.8 kΩ/□) are achieved for the thinnest samples (5 nm). Although these values are in the range of other thin films prepared with graphene, these films are fundamentally different since they are composed entirely of graphene flakes joined by a carbon matrix, which presents a high density of defects; thus they are also interesting candidates for flexible and transparent electronics, especially when biocompatibility, friction, high temperature, UV radiation, and corrosion resistance are also needed.