Al-Doped ZnO Thin Film: A New Transparent Conducting Layer for ZnO Nanowire-Based Dye-Sensitized Solar Cells

In this study, an aluminum-doped zinc oxide (AZO) layer was used as a transparent conducting oxide (TCO) layer in ZnO nanowire (NW)-based dye-sensitized solar cells (DSSCs). The well aligned, single crystalline ZnO NW arrays that were grown on the AZO films exhibited a better DSSC performance (an increased photocurrent density and fill factor) than those grown on the fluorine doped tin oxide (FTO) films. The I-V characteristics and electrochemical impedance spectroscopy measurements for the ZnO NW arrays on the AZO and FTO films clearly showed that the superior DSSC performance was caused by the facilitated charge injection from the ZnO NW to AZO, resulting from the formation of an ohmic contact. This study demonstrates that the AZO films are more favorable for highly efficient ZnO NW-based photoenergy conversion devices.