Thermally grown ZnO nanosheets for high efficiency dye-sensitized solar cells.

High efficiency dye-sensitized solar cells (DSSCs) were fabricated using ZnO nanosheet electrodes. ZnO nanosheets were synthesized on top of fluorine-doped tin oxide (FTO) glass using Zn(OAc)2 as a precursor in the gold catalyzed chemical vapor deposition (CVD) method at a temperature of 800-900 degrees C. The synthesized materials were characterized by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), and Raman and photoluminescence (PL) spectroscopy. Typical DSSCs with ZnO nanosheets achieved moderately good conversion efficiency eta of approximately 2.12% with short-circuit current density J(SC) = 3.56 mA/cm2, open-circuit voltage V(OC) = 0.831 V, and fill factor FF = 71%. The high J(SC) and eta are attributed to high dye absorption through high surface ZnO nanosheets, which increased the light harvesting. The lower recombination rate was also observed in the ZnO nanosheet electrodes, resulting in high values of V(OC) and FF in the DSSCs.