High catalytic activity and stability of nickel sulfide and cobalt sulfide hierarchical nanospheres on the counter electrodes for dye-sensitized solar cells.

In situ grown nickel sulfide and cobalt sulfide hierarchical nanospheres on F-doped SnO2 (FTO) substrates exhibited comparable catalytic activities to sputtering Pt on the counter electrodes for dye-sensitized solar cells (DSSCs). The fresh cells with the nickel sulfide and cobalt sulfide on the counter electrodes could reach power conversion efficiencies of 6.81% and 6.59% respectively, approaching an efficiency of 6.85% based on the sputtering Pt counter electrode. Both nickel sulfide and cobalt sulfide counter electrodes could maintain the cell's relatively high performance in the long-term stability test in 504 hours.