Dye-sensitized solar cells with TiO₂ electrode modified by ZrO₂, CeO₂, or ZnO

Abstract

This research investigated the application of ZrO₂/TiO₂, CeO₂/TiO₂ or ZnO/TiO₂ composite thin film as an electrode layer for a dye-sensitized solar cell (DSSC) and the effect on the fabrication of double-layer structure of the thin film electrode the performance of DSSC. Each metal oxide was individually synthesized via sol-gel methods and mixed before being sprayed onto the fluorine doped tin oxide (FTO) glass substrates using an ultrasonic spray coater. The electrode layer was fired at 400℃ for two hours. The amount of ZrO₂, CeO₂, or ZnO added to TiO₂ was varied from 0 to 10%wt (for ZrO₂) and 0 to 7% wt (for CeO₂, or ZnO). The DSSC with pure TiO₂ electrode layer had the efficiency of 4.77±0.48%. The addition of CeO₂ appeared to reduce the cell efficiency significantly.On the other hand, the addition of ZrO₂ or ZnO increased the amount of dye molecules adsorbed on the electrode surface, leading to improved short circuit current density (J[subscript SC]) and the efficiency of the cells when compared to cells with pure TiO₂ electrode. The highest cell efficiency of 6.57±0.26% and 6.55±0.10% were obtained for the DSSC with 7wt% ZrO₂/TiO₂ and 5wt% ZnO/TiO₂ electrode, respectively. Double-layer electrode (7wt% ZrO₂/TiO₂ on top of pure TiO₂) brought about better light scattering, thereby enhancing the overall energy conversion efficiency from 6.57±0.26% to 9.28±0.34% when compared with single-layered ZrO₂/TiO₂ electrode.