Synthesis and characterization of ZnO nanowires grown on different seed layers: The application for dye-sensitized solar cells

Zinc oxide (ZnO) nanowire electrodes which were grown on different seed layers and examination of their significant effects on the performance of dye sensitized solar cells were studied. Through chemical bath deposition process, the ZnO nanowires were grown on an indium tin oxide (ITO) coated glass using sputter-deposited aluminum doped zinc oxide (AZO) and ZnO seed layers. Afterward, main parameters such as solution concentration, growth temperature, and time were systematically investigated based on morphology of nanowires. The X-ray diffraction (XRD), field emission scanning microscopy (FESEM), and photoluminescence (PL) were applied to investigate the characteristics of the samples. The results showed ZnO nanowires, which were grown by AZO seed layer, had a high density array with hexagonal wurtzite structure distributed vertically and uniformly on ITO coated glass. The mentioned zinc-oxide nanowires grown under an optimum condition on different seed layer were used to fabricate dye solar cells afterward. The seed layer was effective on morphologic, optical, and structural features. The overall light-conversion efficiency of dye sensitized solar cell with ZnO nanowires grown on AZO seed layer was almost 2 times higher than that of those grown on ZnO seed layer. Electrochemical impedance spectroscopy analysis was measured under standard light to investigate the electron transport properties in the both ZnO-NW DSSCs. As the results showed, photoanode electron recombination rate with electrolyte was 6.02 Hz for dye solar cells of zinc oxide (ZnO-NWDSSC) produced by ZnO seed layer, which is 2.5 times faster than cells with AZO seed layer.