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)2·2H2O] and ethanol. The effects of the concentration of Zn(CH3COO)2·2H2O 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)2·2H2O) 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.

► Effects of Zn(AC)2·2H2O concentration and dipping time on the band gap were examined.
► Band gap of a ZnO-coated TiO2 (3.75 eV) exceeded that of TiO2 electrode (3.22 eV).
► Efficiency of DSSC with a ZnO barrier (6.7%) exceeded that of typical DSSC (5.9%).