Abstract
This study investigates the optimization of a ZnO-coated TiO2 working electrode and the effect of this hybrid electrode on the power conversion efficiency of a dye-sensitized solar cell (DSSC). This electrode was 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 effect of the concentration of Zn(CH3COO)(2) center dot 2H(2)O on the band gap of a working electrode and on the power conversion efficiency of a DSSC was also examined. As the concentration of ZnO decreased to 0.002 from 0.004 mol/L, the band gap of the working electrode decreased to 3.08 eV from 3.87 eV, and the power conversion efficiency (eta) of the DSSC increased to 3.8573% from 3.3514%. Interestingly, the eta of DSSC with a ZnO-coated TiO2 hybrid electrode substantially exceeded that of the conventional DSSC due to TiO2 orbital hybridization and an energy barrier between ZnO and TiO2 that suppressed the electron recombination.