Effects of Ethanol on Optimizing Porous Films of Dye-Sensitized Solar Cells

Abstract

Solvent, dispersant, and surfactant play different roles in forming porous films of dye-sensitized solar cells (DSSCs) when they are added into the paste. We investigate the influence of ethanol, acetylacetone, and Triton-X100 on the photoelectrode of DSSCs with orthogonal array design experiments. Stereoscopic morphologies of photoelectrodes scanned with atomic force microscopy (AFM) show that decreasing the amount of ethanol in TiO 2 paste results in forming a more compact structure of the photoelectrode for DSSCs. The TiO 2 photoeletrode made with 2.5 g of TiO 2 nanoparticle powder dissolved in 20 mL of ethanol presents lower root-mean-square (rms) roughness calculated from AFM, and its corresponding performance in DSSCs shows higher photoelectric conversion efficiency, while the effects of acetylacetone and Triton-X100 on the performance of DSSCs are not very apparent. Optimized photoelectrode dyed with N719 shows increased light absorption. This may result from adsorbing more amount of dye on a larger inner area of the porous photoelectrode. We find that the DSSC with the photoelectrode made from 2.5 g of TiO 2 nanoparticle powder dissolved in 20 mL of ethanol containing 0.8 mL of acetylacetone and 0.6 mL of Triton-X100 shows a large increase in short-circuit current density ( J sc ) and a little improvement in open-circuit voltage ( V oc ). At the optimized point, photoelectric conversion efficiency of 6.1% is obtained.