Catalytic properties of the cobalt silicides for a dye-sensitized solar cell

The cobalt silicides were investigated for employment as a catalytic layer for a DSSC. Using an E-gun evaporation process, we prepared a sample of 100 nm-thick cobalt on a p-type Si (100) wafer. To form cobalt silicides, the samples were annealed at temperatures of 300 °C, 500 °C, and 700 °C for 30 minutes in a vacuum. Four-point probe, XRD, FE-SEM, and CV analyses were used to determine the sheet resistance, phase, microstructure, and catalytic activity of the cobalt silicides. To confirm the corrosion stability, we also checked the microstructure change of the cobalt silicides after dipping into iodide electrolyte. Through the sheet resistance and XRD results, we determined that Co2Si, CoSi, and CoSi₂ were formed successfully by annealing at 300 °C, 500 °C, and 700 °C, respectively. The microstructure analysis results showed that all the cobalt silicides were formed uniformly, and CoSi and CoSi₂ layers were very stable even after dipping in the iodide electrolyte. The CV result showed that CoSi and CoSi₂ exhibit catalytic activities 67 % and 54 % that of Pt. Our results for Co₂Si, CoSi, and CoSi₂ revealed that CoSi and CoSi₂ could be employed as catalyst for a DSSC.