Improving the Efficiency of Dye-Sensitized Solar Cells by Growing Longer ZnO Nanorods on TiO₂ Photoanodes

Abstract

By increasing the temperature of hydrothermal reactions from 70 to 100 ∘ C, vertically aligned ZnO nanorods were grown on the TiO 2 thin film in the photoanode of dye-sensitized solar cells (DSSCs) as the blocking layer to reduce the electron back recombinations at the TiO 2 /electrolyte interfaces. The length effects of ZnO nanorods on the photovoltaic performances of TiO 2 based DSSCs were investigated by means of scanning electron microscope, X-ray diffractometer, photoluminescence spectrophotometer, and the photocurrent-voltage measurement. Under the illumination of 100 mW/cm 2 , the power conversion efficiency of DSSC with ZnO nanorods decorated TiO 2 thin film as its photoanode can be increased nearly fourfold from 0.27% to 1.30% as the length of ZnO nanorods increases from 300 to 1600 nm. The enhanced efficiency of DSSC with ZnO nanorods decorated TiO 2 thin film as the photoanode can be attributed to the larger surface area and the lower defect density in longer ZnO nanorods, which are in favor of more dye adsorption and more efficient transport in the photoanode.

Synthesis and Luminescence Characterization of Downconversion and Downshifting Phosphor for Efficiency Enhancement of Solar Cells: Perspectives and Challenges

“…Chander et al 213 recently demonstrated that YVO 4 :Eu 3+ nanophosphors on a TiO 2 photoanode enhanced the absorbance and environmental stability of dye-sensitized solar cells. The efficiency of dye-sensitized solar cells using ZnO nanorods with decorated TiO 2 thin film as the photoanode was reported to have increased by Zhai et al 214 These improvements can be attributable to the longer ZnO nanorods' higher surface area and lower flaw density. The circumstances are favorable for increased dye absorption and improved transport efficiency in the photoanode.…”

Performance of Dye Sensitized Solar Cells (DSSCs) with ZnO Nanorod Electrode in Different Seed Solution

“…This proves that the size of the diameter and absorbance at the photoanode which is influenced by a good seed solution will affect the performance of DSSCs. The smaller diameter of the ZnO nanorod in sample 2 provides a larger surface area then increasing the total amount of dye attached to the ZnO nanorod and improve the photovoltaic performance [20].…”