Abstract
In dye-sensitized solar cells (DSSCs), the property of TiO2/dye/electrolyte interface affects photoelectron conversion greatly owing to the electron recombination reaction. Here, acid treatment generates excess surface charge on anatase TiO2 nanoparticles, resulting in the change of the TiO2/dye/electrolyte interface property, which leads to improvement of photoelectron conversion. Acid-treated TiO2 analyzed by SEM, EDS, XRD, zeta-potential meter, and flat band potential, were made as the working electrode in DSSC device. The surface treatment only resulted in the change in surface charge, while the structure and composition of the modified TiO2 remained unchanged. Acid-treated TiO2 had excess H+ on the surface and lowed flat band potential than that of untreated TiO2. The modified TiO2 provided remarkably improved photocurrent performance but reduced photovoltage. Additionally, electrochemical impedance spectroscopy was employed to study the interfacial reaction of the cell. It is found that using acid-treated TiO2 as the electrode reduces the charge-transfer resistance at the TiO2/dye/electrolyte interface by lowering the possibility for the recombination reaction, which strongly improved photoelectron conversion.