Reduced graphene oxide for Pt-free counter electrodes of dye-sensitized solar cells

Abstract

Here, we report on reduced graphene oxide (rGO) electrode prepared by doctor-blading a viscous rGO paste on FTO substrate followed by sintering at 500°C in argon and its application asa counter electrode (CE) of dye-sensitized solar cells (DSSCs). The paste was prepared by mixing rGO and ethyl cellulose in terpineol. The rGO was prepared from commercially available graphite flakes, which were first oxidized to graphene oxide (GO) by modified Hummers’ process and then the GO was reduced to rGO with hydrazine. Electrochemical analyses – cyclic voltammetry and electrochemical impedance spectroscopy – suggest that the performance of the rGO electrode towards I−/I3− is comparable to that of Pt electrode. Even though the catalytic performance of the rGO film towards the reduction of triiodide was not as good as thermally decomposed Pt electrodes, the overall series resistance of the rGO-based cell was similar to that of the Pt-based cell. When applied to DSSCs asa CE, the rGO electrode performs like a Pt electrode showing the prospect of replacing Pt with a metal-free all-carbon material.