Mesoporous Electrodeposited-CoS Film as a Counter Electrode Catalyst in Dye-Sensitized Solar

In this study, a mesoporous CoS film was deposited onto a fluorine-doped tin oxide glass substrate to form a counter electrode (CE) in dye-sensitized solar cell (DSSC) using a potentiodynamic deposition in the presence of thiourea (TU). The function of potentiodynamic deposition used to prepare the mesoporous CoS CE was firstly investigated. It can be found that the reverse sweep (0.2 V to -1.2 V vs. Ag/AgCl) can facilitate the formation of CoS with excellent electrocatalytic activity for I-/I-3(-) redox reaction, and the forward sweep (-1.2 V to 0.2 V vs. Ag/AgCl) can profit the deposit with crude morphology to increase its active surface area. Moreover, TU was found to act as an accelerator to enhance the deposition rate, thus the concentration of TU did result in the change in the surface morphology and electrocatalytic behaviors of CoS deposit. After the optimization of TU concentration, a DSSC assembled with a CoS CE prepared in 0.75 M TU showed a superior cell efficiency of 6.22% in comparison to a DSSC with a sputtered-Pt CE (5.80%). This enhanced efficiency was attributed to the increased active surface area and the lower charge transfer resistance for I-3(-) reduction. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.036202jes] All rights reserved.