Electrochemical impedance and X-ray absorption spectroscopy analyses of degradation in dye-sensitized solar cells containing cobalt tris(bipyridine) redox shuttles

/electrolyte interface. High-resolution fluorescence detected X-ray absorption spectroscopy (HERFD-XAS) was performed to identify the reduction of a part of Co(III) to Co(II) after ageing, by investigating the Co K absorption edge. The HERFD-XAS data suggested a partial reduction of Co(III) to Co(II), accompanied by a difference in symmetry of the reduced species.