Assessment of TiO 2 Blocking Layers for Cu II/I -Electrolyte Dye-Sensitized Solar Cells by Electrochemical Impedance Spectroscopy.

The TiO 2 blocking layer in dye-sensitized solar cells is the most difficult component to evaluate at thicknesses below 50 nm, but it is crucial for the power conversion efficiency. Here, the electrode capacitance of TiO 2 blocking layers is tested in aqueous [Fe(CN) 6 ] 3-/4- and correlated to the performance of photoanodes in devices based on a [Cu(tmby) 2 ] 2+/+ electrolyte. The effects of the blocking layer on electronic recombination in the devices are illustrated with transient photovoltage methods and electrochemical impedance analysis. We have thus demonstrated a feasible and facile method to assess TiO 2 blocking layers for the fabrication of dye-sensitized solar cells.