A counter electrode of multi-wall carbon nanotubes decorated with tungsten sulfide used in dye-sensitized solar cells

Multi-wall carbon nanotubes decorated with tungsten sulfide (MWCNTs-WS2) were synthesized by using a hydrothermal method, and used as a low-cost platinum-free counter electrode for dye-sensitized solar cell (DSSC). Cyclic voltammetry and electrochemical impedance spectroscopy characterizations indicate that the counter electrode has a high catalytic activity for the reduction of triiodide to iodide and a low charge transfer resistance at the electrolyte–electrode interface. A DSSC based on this counter electrode achieves a high power conversion efficiency of 6.41% under a simulated solar illumination of 100 mW cm−2 (AM 1.5). This efficiency is comparable to 6.56% for a DSSC with Pt counter electrode.