Improved performance of TiO2 electrodes coated with NiO by magnetron sputtering for dye-sensitized solar cells

TiO2 electrodes are coated with NiO by DC magnetron sputtering, and their structural, optical and electrochemical performance has been investigated. X-ray diffractometry (XRD), UV-vis spectrophotometry, scanning electron microscopy (SEM), AC impedance, and linear sweep voltammetry (LSV) are used to characterize the TiO2/NiO electrodes. Their performance is evaluated with a computer controlled electrochemical workstation in combination with three conventional electrodes. The experimental results indicate that the surface modification of TiO2 electrodes with sputtered NiO reduces trap sites on TiO2 and improves the electrochemical performance of dye-sensitized solar cells (DSSCs). Sputtering NiO for 7 min, which is about 21 nm thick, on 6.5 μm thick TiO2 greatly improves the DSSC parameters, and the conversion efficiency increases from 3.21 to 4.16%. Mechanisms of the influence of the NiO coating on electrochemical performance are discussed.