Two flexible counter electrodes based on molybdenum and tungsten nitrides for dye-sensitized solar cells

Two novel flexible counter electrodes (CEs) on Ti sheets using molybdenum and tungsten nitrides (Mo(2)N, W(2)N) as catalysts were synthesized and used in a dye-sensitized solar cell (DSC) system. High catalytic activity of the two nitride CEs for the reduction of triiodide were proved by cyclic voltammetry, electrochemical impedance spectroscopy and Tafel-polarization measurements. The DSCs based on Mo(2)N and W(2)N CEs achieved power conversion efficiencies of 6.38 and 5.81%, reaching 91 and 83% of the photovoltaic performance of the DSC using a Pt CE, respectively. This research paves a promising way to develop new CE catalysts and reduce the cost of DSCs.