Effects of RF and pulsed DC sputtered TiO2 compact layer on the performance dye-sensitized solar cells

Abstract

We investigated the characteristics of TiO2 compact layers grown by RF and pulsed DC magnetron sputtering on F-doped SnO2 (FTO) electrodes from a TiO2 ceramic target. The morphological and microstructural properties of the formed TiO2 layers were characterized by scanning electronic microscopy and X-ray diffraction. The deposition rate of the compact TiO2 layer by pulsed DC sputtering was much higher than that of RF deposition under the same sputter power and deposition pressure. Moreover, it was found that the power conversion efficiency of the dye-sensitized solar cells (DSCs) is strongly dependent on the thickness of both RF and DC sputtered TiO2 layer inserted between FTO electrode and nanoporous TiO2 layer. The thickness of the sputtered TiO2 layer was changed from 0 to 200nm. The electrochemical impedance spectroscopy (EIS) technique was employed to evaluate the recombination resistance and electron lifetime in DSCs with differently thick TiO2 passivating films. The DSC fabricated on 160nm thick TiO2 passivating FTO electrode showed the maximum power conversion efficiency of 7.90% due to highly effective prevention of the electron transfer to electrolyte.