Influence of Electrolyte Composition on the Photovoltaic Performance and Stability of Dye-Sensitized Solar Cells with Multiwalled Carbon Nanotube Catalysts

Efficient dye-sensitized solar cells (DSCs) were realized by using multiwalled carbon nanotubes (CNTs) as the counter-electrode catalyst. The catalytic layers were produced from an aqueous paste of mass-produced raw CNTs with carboxymethylcellulose polymer by low-temperature (70 degrees C) drying. We found that the highly disordered CNTs played the important role of increasing the fill factor of DSCs with electrolytes including large molecules and that the presence of Li+ as the counter charges for I-3(-)/I- redox couples reduced the chemical stability when using the CNT catalyst. Our experiments showed that by replacing the conventional Pt catalyst and Li+-based electrolyte with the proposed CNT catalyst and an electrolyte containing 1-butyl-3-methylimidazolium cations instead of Li+, the energy conversion efficiency increased from 6.51% to 7.13%. This result suggests that highly defective CNT catalysts prepared by low-temperature drying are viable cost-effective alternatives for DSCs, as long as the electrolytes composition is optimized.