Functionalized Reduced Graphene Oxide Loaded Aligned Carbon Nanotube Layer Used as Counter Electrode for Dye-Sensitized Solar Cells.

A novel bilayer counter electrodes for Dye-sensitized Solar Cells (DSSCs) made of reduced graphene oxide (RGO) and aligned carbon nanotube (ACNT) was developed. The underlayer ACNT severs as a transition layer for RGO. The overlayer of RGO plays the role of catalytic layer. It was demonstrated that the property of graphene counter electrode was adversely affected by aggregation, by adding surfactant, the aggregation of graphene can be inhabited effectively. Moreover, the interface between the RGO and the ACNT can be optimized by surfactant functionalization of RGO. After screening, a cationic surfactant cetylpyridinium chloride (CPC) functionalized RGO, code as CPC-RGO, exhibits the best performance. Compare to the ACNT based counter electrode and other surfactant functionalized RGO/ACNT based bilayer counter electrodes, the CPC-RGO/ACNT reduced interface resistance and improved the double chemical capacitance efficiently, thus uplifting the short circuit current density and fill factor from 7.35 to 8.8 mA cm-2, and 59.87 to 62.79, respectively. Eventually, the CPC-RGO/ACNT based DSSC giving a power conversion efficiency of 3.9%, which is 1.24-fold than that of ANCT based DSSC, because of the best splay degree of CPC/RGO.