Directly Determine an Additive-Induced Shift in Quasi-Fermi Level of TiO2 Films in Dye-Sensitized Solar Cells

The shifts in quasi-Fermi level (QFL) of TiO2 films affected by additives are directly measured using three-electrode dye-sensitized solar cells (DSCs). The difference in QFL of TiO2 under short circuit and open circuit are also analyzed. It is found that the QFL difference between the electrolyte side of the TiO2 film and the equilibrium redox potential, as well as the QFL difference between the two sides of the TiO2 film shift to higher potential owing to the addition of TBP to the electrolyte. The shift values are influenced by the cations present in the electrolyte. These directly determined changes in QFL in TiO2 films both under open circuit and short circuit may provide valuable information for studying DSC operation mechanisms such as the dynamics of charge separation and charge recombination processes. (C) 2012 The Japan Society of Applied Physics