Effect of Nickel–Zinc Co-doped TiO2 blocking layer on performance of DSSCs

Abstract

Photovoltaic parameters in Dye-sensitized solar cells (DSSCs) are improved through the employment of Ni and Zn co-doped TiO2 thin film as a Photo-anode material in DSSCs. The TiO2 layers having different ratio of Ni and Zn were deposited over fluorine doped tin oxide (FTO) substrate using the spin coating technique. Organic dyes like mercurochrome (MC) dye were emerged out to use as sensitizer with TiO2 photoanode based DSSCs. The optical property of bare TiO2, NZT-20, NZT-40, NZT-60 and NZT-80 blocking layer prepared by using Ni and Zn-doped TiO2 with different doping concentrations were studied. The values of the bandgap were found to be 3.83, 3.78, 3.82 and 3.83 eV for TiO2 doped with Ni and Zn concentrations such as NZT-20, NZT-40, NZT-60 and NZT-80 respectively. Electrochemical impedance spectroscopy (EIS) was used to study the charge transfer resistance and interfacial capacitances that are present in a DSSCs. The EIS measurements are used to calculate values of charge transfer capacitance and resistance of all samples. The NZT-80 sample has a high value of resistance and capacitance so that it affects the photovoltaic performance of DSSC. The Blocking layer incorporated in NZT-80 sample gives 61% increased in the efficiency as compared to its bare TiO2 (without Co-doped Ni–Zn) photoanode.