Electrochemical Exfoliation of Graphene Flake Embedded in SiNWs as Counter Electrode for Dye-Sensitized Solar Cells

Abstract

In this paper, a three-dimensional graphene wrapped silicon nanowire (SiNWs) architecture was synthesized by electrochemical exfoliation method and proposed to be the counter electrode for dye-sensitized solar cells (DSSCs). The results show that the few high-quality layers of graphene sheets have been obtained by electrochemical exfoliation method. The size of graphene is distributed from 550[Formula: see text]nm to 650[Formula: see text]nm, appropriately dispersed onto the SiNW supporter. The graphene/SiNW nanostructure still vertically aligned to the substrate finely. The channel between each wire is clear. The fabricated graphene/SiNWs electrode is a promising structure for future applications. The performance of the graphene/SiNWs as the counter electrode is found to be dependent on its dispersion in the whole backbone, with better dispersion offering more surface areas for the catalytic reduction reaction. Electrochemical tests reveal that the DSSC with graphene/SiNWs exhibits higher electro-catalytic activity and lower charge transfer resistance, suggesting that the 3D structure presents a potential way to fabricate low-cost, integrated and metal-free counter electrode for high-performance DSSCs. The DSSC based on graphene/SiNWs has an open-circuit voltage ([Formula: see text]) of 738.11[Formula: see text]mV, short-circuit current density ([Formula: see text]) of 15.48[Formula: see text]mA cm[Formula: see text], fill factor (FF) of 0.67 and conversion efficiency ([Formula: see text]) of 7.66%.