Effective Work Function of Screen Printable Graphene-Decorated Conductive Nanocomposites

Printable electrodes will play an important role in future flexible electronics in photovoltaic, displays, and sensor devices. Novel materials such as nanocomposites can be attractive as electrode materials in such devices. Work function is an important parameter in the design of device structures for optimal performance. However, definition of work function of nanocomposite materials is complicated due to their non-homogeneity compared to single phase materials. In this study, an effective work function of a novel screen-printable graphene-decorated nanocomposite is presented. Two methods were used to determine the effective work function. The first method relies on the tunneling current in a conductor-insulator-conductor structure with the nanocomposite functioning as one of the conductors, while the second method measures the work function of the nanocomposite at the interface with vacuum using ultraviolet photoemission spectroscopy. Values measured using the two methods are in a fairly good agreement. The difference is believed to be due to the heterogeneous nature of this nanocomposite which invites for the definition of an effective value for the work function, which will be a key parameter in the design of practical devices with nanocomposite electrodes.