Controlled Growth of CuS on Electrospun Carbon Nanofibers as an Efficient Counter Electrode for Quantum Dot-Sensitized Solar Cells

One-dimensional CuS/electrospun carbon nanofiber heteroarchitectures (CuS/EC) with high catalytic activity have been successfully fabricated by combining the versatility of the electrospinning technique and following a hydrothermal process. The CuS nanoparticles as the secondary nanostructures were uniformly grown on the primary electrospun carbon nanofibers with good dispersion by optimizing reaction conditions. It was found that the L-cysteine used as the sulfur donor and chelating reagent was favored for the growth of CuS on the carbon fibers. A possible formation mechanism and growth process of the CuS nanoparticles on the carbon fibers is discussed based on the experimental results. The as-prepared CuS/EC composite was then spray-deposited on FTO glass and demonstrated good performance in quantum dot-sensitized solar cells (QDSCs), which was higher than the conventional Pt electrode. The good performance is attributed to its heteroarchitecture. The CuS nanoparticles with high catalytic activity play the main role in the reduction process of the oxidized polysulfide, while the carbon nanofibers with the 3-D mat morphology bridge all the CuS nanoparticles as the framework and facilitate the charge transport during the catalysis process.