Influence of the binder on the electron transport in the dye-sensitized TiO2 electrode

Surface photovoltage spectroscopy and electric field induced surface photovoltage spectroscopy (EFISPS) were used to study the influence of the polyethylene glycol (PEG) as the binder on the electron transport in the dye-sensitized 7 μm TiO2 film electrode. The photovoltage of the TiO2 electrode prepared without PEG was higher than that of the electrode with binder, which showed that the charge transport properties of the TiO2 electrode were improved in the absence of the binder. After the electrode prepared with the binder was applied with + 0.5 V voltage, three photovoltage peaks appeared at 432, 385 and 343 nm in the EFISPS, indicating that there existed impurity states in the electrode due to the carbonization of the PEG. When the TiO2 electrode prepared with binder was applied to the dye-sensitized solar cell, the photogenerated electrons from the excited dye could be trapped by these impurity states.