The crystalline structure and surface morphology of TiO2 semiconductor coating play an important role in the conversion efficiency of dye-sensitized solar cells.In order to obtain TiO2 coating with controllable morphology and high porosity,nanoporous TiO2 films were fabricated on conducting glass(FTO) substrates,Ti thin films(1.5-2 μm) were deposited on conducting glass(FTO) substrates via the DC sputtering method,and then electrochemically anodized in NH4F/ethylene glycol solution.The crystalline structure and surface morphology of the samples were characterized by X-ray diffraction(XRD) and field emission scanning electron microscopy(FESEM),respectively.The influences of anodizing potential,electrolyte composition,and pH value on the surface morphology of nanoporous TiO2 films were extensively studied.The growth mechanism of nanoporous TiO2 films was discussed by current density variations with anodizing time.The results demonstrate that nanoporous TiO2 films with high porosity and three-dimensional(3D) networks are observed at 30 V,when the NH4F concentration in ethylene glycol solution is 0.3%(mass fraction) and the electrolyte pH value is 5.0.
