Performance Improvement of Dye-Sensitized Solar Cells Using a Combination of TiO₂ and ZnO as Photoanodes

Abstract

TiO2 are usually used as photoanode to get high-performance dye-sensitized solar cells (DSSCs). TiO2 has good chemical stability, but still has poor electron mobility so that the DSSC efficiency is low. An alternative semiconductor metal-oxides such as ZnO currently are being explored due to ease of processing, higher electron mobility, interface band energetics, and can be utilized as photoanode also, but the chemical stability is low. Based on these facts, by combining the advantages of TiO2 and ZnO, the TiO2:ZnO composite can be an ideal material as a photoanode in DSSC. In this study, composite of TiO2:ZnO was synthesized using sol-gel method with ratio of TiO2 to ZnO were varied from 80:20, 60:40, 50:50, 40:60, and 20:80 in atomic percent. DSSCs were fabricated by coating the photoanode using screen-printing technique on a FTO-glass substrate. Composite of TiO2:ZnO photoanodes were then sensitized in a solution of N719 dye for several hours. Finally, the DSSCs were assembled and the power conversion efficiency was measured using an I–V measurement system. The highest power conversion efficiency of 2.30% was obtained from the cell fabricated with TiO2:ZnO (50:50) photoanode. This result indicated that the balanced composition allowed to increase Jsc along with reducing recombination process and retaining high dye-loading capability.