The dye adsorption optimization of ZnO nanorod-based dye-sensitized solar cells

• Two strategies were employed to enhance the dye adsorption of ZnO nanorod-based DSSCs.
• The density of the nanorod arrays increased with increasing the thickness of ZnO seed layers.
• The adsorption saturated after 4 cycles of desorption/adsorption process.
• An approximately 100% increase in conversion efficiency is achieved.

A critical factor in enhancing the conversion efficiency of ZnO nanorod array-based dye-sensitized solar cells (DSSCs) is the dye adsorption, which is determined by the dye adsorptivity of single nanorod and the density of nanorod arrays. We show that the density of the nanorod arrays increases gradually with increasing seed layer thickness, resulting in an enlarged surface area for dye adsorption. In addition, increasing the number of desorption/adsorption cycles can also lead to a continuous increase in the total amount of dye loading. As a result, we observe a significant enhancement in the photocurrent densities and conversion efficiencies of ZnO nanorod array-based DSSCs.