Investigating the Effect of Thickness on the Performance of ZnO-based DSSC by Electrochemical Impedance Spectroscopy Technique

Due to the unique properties of ZnO nanostructures, they are widely used as photoanode substrate in dye sensitized solar cells (DSSCs). In the present study, a composite of ZnOnanoparticles paste was synthesized by sonochemical method. The composite was made using two different nanoparticles approximately 35 and 350 nanometers particle sizes considering the respect ratio of 3:1 involving the main and scattered layers. To investigate the cell performance,different ZnO film thicknesses of photoelectrodes were prepared to obtain efficient performance. The cells were fabricated using N719 ruthenium dye and all photovoltaic parameters such asshort circuit current density (JSC), open circuit voltage (VOC), fill factor (FF) and conversion efficiency (η) measured as well. Electrochemical impedance spectroscopy (EIS) as a powerful technique was employed to determine an appropriate equivalent circuit for studying the electron lifetime, charge transport and transfer resistances in all fabricated cells where the EIS resultsshow appropriate agreement with the measured device performance parameters. The results demonstrate the ZnO thickness is a critical parameter for providing sufficient resistance to suppress the charge recombination process and transporter electrons. Consequently the highestoverall power conversion efficiency (3.61%) was obtained where the thickness of photoelectrode was optimized around 21-μm-thick by doing three times Dr. Blade deposition method.

کلیدواژه ها:

ZnO-based DSSC ، Electrochemical impedance spectroscopy ، Electron lifetime ، Nanocomposite ، Sonochemical method