Effects of CdS-TiO<sub>2</sub> Working Electrode Layer on Dye Sensitized Solar Cell Investigated by Impedance Spectroscopy

Abstract

The efficiency of dye-sensitized solar cell (DSSC) has been improved by various ways. In this work, The CdS nanoparticles were added in the TiO2 working electrode for improving the efficiency of DSSC. The DSSC structure comprises of TiO2 working electrode with and without CdS powder, Pt counter electrode, rutherium (II) (N719) dye and lithium iodide electrolyte. Normally, the TiO2 paste was screened for five layers. In this work, the TiO2 paste with CdS nanoparticles was screened for various numbers of layers on the layers of pure TiO2 to get the total of five layers. Then TiO2 mixed and unmixed CdS nanoparticles and Pt films were annealed at the temperature of 500°C for 50 min. Impedance spectroscopy (IS) was used to study charge transport in each interface of DSSC. For illumination condition, the measured IS can be divided into three regions that were charge transport at Pt layer, charge transport at working electrode/dye/electrolyte interface and ion contribution at electrolyte layer. The carrier transport parameters extracted from fitting IS spectra were chemical capacitance, charge transfer resistance and time constant.