Lithium-functionalized graphene oxide with a low load of Pt as an efficient counter electrode for dye-sensitized solar cells.

Low-cost materials with excellent chemical stability, high conductivity, and catalytic properties have attracted much attention as an alternative to conventional Pt counter electrodes in dye-sensitized solar cells (DSSCs). Herein, graphene oxide (GO) sheets were successfully synthesized via the improved Hummers' method, functionalized with lithium and characterized by SEM, AFM, XRD, Raman, UV–Vis, and FTIR techniques. The impact of GO thickness, heat treatment temperature, and hybridization with Pt particles on photovoltaic performance of the counter electrodes (CEs) were studied. A solar efficiency of 2.47% and 2.94% was achieved for the pristine GO and Li-functionalized GO electrodes, respectively, under an optimized condition. A hybrid structure of GO or Li-functionalized GO films coated with an ultra-thin Pt film (i.e., GO-Pt or LiGO-Pt CEs) led to a remarkable efficiency of 7.07% and 8.87%, respectively. Such superior photovoltaic performance of LiGO-Pt CE indicated an increase of 61% in cell efficiency compared to the conventional Pt counter electrodes. The design of GO-based counter electrodes decorated with Pt deposition and Li functionalization will open a new concept for improvement of power conversion efficiency of DSSCs. [ABSTRACT FROM AUTHOR]