Ternary Ni0.5Zn0.5Fe2O4/carbon nanocomposite as counter electrode for natural dye-sensitized solar cells: Electro-photovoltaic characterizations

Abstract The most notable counter electrode (CE) in dye-sensitized solar cells is platinum (Pt), which is expensive and scarce. Here, Ni0.5Zn0.5Fe2O4/carbon (NZF/C) composites containing different ratios of carbon were synthesized and used as novel counter electrodes. NZF/Cs have specific surface areas of 109.3–128.6 m2 g–1, pore sizes of 99.4–119.6 A, and bandgap energies of 2.36–2.99 eV, according to the characterization results. The catalytic activities of NZF/C CEs were verified by electrochemical impedance spectroscopy and cyclic voltammetry. NZF/Cs demonstrated outstanding catalytic activities in the reduction of I3− and had performance comparable to Pt CEs in the dye-sensitized AgNP/TiO2 DSSCs. For the natural betalain dye, NZF/C–1 CE demonstrated a 2.75% efficiency with a short circuit current density of 4.13 mA cm–2 and a fill factor of 50.71%, which was very competitive with Pt CE's 2.83% efficiency. During 30 days of stability testing, NZF/C–1 CE maintained a photon conversion efficiency of 7.18% and a fill factor of 55.57% for Z-907 synthetic dye. The high electrocatalytic activity of NZF coupled with the good conductivity of carbon black account for NZF/C performance. The results herein show that NZF/C can be used as a cost-effective and efficient substitute for Pt in DSSCs.