Work-function decrease of transparent conducting films composed of hydrazine-reduced graphene oxide and silver nanowire stacked layers by electrochemical treatment

Equilibrium potentials (EP) of various carbon materials on a glassy-carbon or a gold electrode have been investigated. Among them, hydrazine-reduced graphene oxide (h-rGO) was found to be notable for a marked decrease in EP after cyclic voltammetry (CV) in a negative potential region between -0.3 and -1.6V vs. Ag/AgCl. The resulting h-rGOs indicated work-function (WF) values as small as 3.4-3.8 eV. Transparent conducting films composed of h-rGO/silver nanowire (AgNW)/polymer stacked layers were treated with similar CV using the AgNW layer as an electrode. The WF values of the films decreased from 4.4 to 3.6-4.1 eV, which values are suitable for negative electrodes. X-ray photoelectron spectra showed small oxygen-to-carbon ratios (O/C) for the small-WF samples. The counter cation was also observed, indicating electron doping. Sodium borohydride, whose reduction potential is -1.44V vs. Ag/AgCl, also decreased the WF of the films. (C) 2014 Elsevier B.V. All rights reserved.