The effect of ZnO-coating on the performance of a dye-sensitized solar cell

This study investigates the effect of a ZnO-coated TiO2 working electrode on the power conversion efficiency of a dye-sensitized solar cell (DSSC). This electrode was designed and fabricated by dipping the TiO2 electrode with the TiCl4 treatment in a solution of zinc acetate dehydrate [Zn(CH3COO)(2)center dot 2H(2)O] and ethanol. The effects of the concentration of Zn(CH3COO)(2)center dot 2H(2)O and the duration of dipping on the band gap of a working electrode and the power conversion efficiency of a DSSC were also examined. The band gap of the working electrode increases to 3.75 eV [TiO2 electrode dipped in 0.05 M Zn(CH3COO)(2)center dot 2H(2)O) for 3 min] from 3.22 eV (TiO2 electrode). Interestingly, the power conversion efficiency of the DSSC with a Zn-coated TiO2 electrode (6.7%) substantially exceeds that of the conventional DSSC with a TiO2 electrode (5.9%), and it may be originated from an increased energy barrier between ZnO and TiO2 that reduces the electron recombination rate. (C) 2012 Elsevier Ltd. All rights reserved.