NH(3)-treated WO(3) as low-cost and efficient counter electrode for dye-sensitized solar cells

A novel low-cost and efficient counter electrode (CE) was obtained by treating catalytic inert tungsten trioxide (WO(3)) nanomaterial in NH(3) atmosphere at elevated temperatures. The formation of tungsten oxynitride from WO(3) after NH(3) treatment, as evidenced by X-ray photoelectron spectroscopy and X-ray diffraction, increases the catalytic activity of the CE. Correspondingly, the power conversion efficiency (PCE) of the DSC is significantly increased from 0.9% for pristine WO(3) CE to 5.9% for NH(3)-treated WO(3) CE. The photovoltaic performance of DSC using NH(3)-treated WO(3) CE is comparable to that of DSC using standard Pt CE (with a PCE of 6.0%). In addition, it is also shown that NH(3) treatment is more efficient than H(2) or N(2) treatment in enhancing the catalytic performance of WO(3) CE. This work highlights the potential of NH(3)-treated WO(3) for the application in DSCs and provides a facile method to get highly efficient and low-cost CEs from catalytic inert metal oxides.