Comparison of ZnO and TiO2 nanowires for photoanode of dye-sensitized solar cells

Highlights: ► We have made a careful comparative investigation on ZnO and TiO2 nanowires in application in dye-sensitized solar cells. ► We have found that TiO2 nanowires adsorb less dyes, but they inject electron faster than ZnO nanowires. ► We point out the future direction of improving dye-sensitized solar cells consist of single crystalline nanowires. - Abstract: ZnO and TiO2 single-crystalline nanowires (SCNWs) are considered to be ideal materials for the photoanode of dye-sensitized solar cells (DSSCs) due to their superior property of electron transfer, however, a direct comparison between the above two systems has not been made. In the present work, ZnO and TiO2 SCNWs were synthesized directly on conductive glasses by wet chemical methods, and their sizes were kept identical. After being sensitized by N3 dye, the two kinds of nanowires were employed as photoanodes for assembling DSSCs. Comparative studies show that, although TiO2 SCNWs adsorb less dye molecules, they could effectively retard charge recombination and achieve longer electron lifetime than ZnO SCNWs; as a result, the DSSCs composed of TiO2 SCNWs exhibit higher performance than those of ZnO SCNWs.