An investigation of electrochemical impedance of TiO2-ZnO composite and TiO2-graphene composite in dye-sensitized solar cells, as photoanode

摘要

In recent years global consumption of fossil fuels as the main sources of energy, has created dangerous conditions for environment and wild life. On the other hand, their limited amount of availability and risk of depletion is getting a sensible problem day by day. Hence there have been several efforts in researches to propose alternative solutions for generating electrical energy. One example is the utilization of solar systems. They have become interesting subjects for researchers due to clean electricity production, renewability feature and low fabrication cost. Dye-sensitized solar cells (DSSC) are considered in this paper. They are cheap, but have a rather low efficiency. Therefore they have not been yet completely industrialized. In this study, the aim is to investigate the effect of using different photo anode materials which is the heart of a solar cell on its electrochemical impedance. The TiO2-ZnO and TiO2-graphene composites are used as photoanodes. Analyzing the results show that due to high mobility of graphene, the TiO2-graphene composite has a lower impedance than the TiO2-ZnO variant. As a consequence, the excited electrons are less prone to recombine with holes in HOMO band. These altogether lead to increased cell efficiency. In this article, by incorporating the electrical and optical specifications of Graphene, the efficiency was improved from 2.94% to 6.97%.