Properties of a counter electrode with nickel silicides in a dye sensitized solar cell

Nickel silicide was used as a counter electrode to replace the Pt catalytic layer of a dye-sensitized solar cell (DSSC) device. 50 nm Si/50 nm Ni was formed on glass or quartz by sputtering, and nickel silicides were formed by vacuum heat treatments at 450 and 800 °C for 30 min. X-ray diffraction (XRD) and Auger electron spectroscopy (AES) depth profiling analysis was used to confirm the formation of nickel silicides. Also, cyclic voltammetry (CV) analysis was employed to confirm the catalytic activity, and photovoltaic properties were confirmed using a simulator and potentiostat. The XRD and AES results reveated that NiSi and NiSi₂ were formed by annealing at 450 and 800 °C, respectively. The results of the CV analysis showed that both NiSi and NiSi₂ exhibited catalytic activity. The energy conversion efficiencies (ECE) of DSSCs with NiSi and NiSi₂ catalysts were 1.31% and 3.86%, respectively, while the device employing the Pt catalyst showed an ECE of 5.49%. This result implies that NiSi₂ can replace Pt when the processing condition is optimized.