Optimization of iodide ion conductivity and nano filler effect for efficiency enhancement in polyethylene oxide (PEO) based dye sensitized solar cells

Abstract

Efficiency enhancement is achieved in dye sensitized solar cells (DSSCs) fabricated with polyethylene oxide (PEO) based gel electrolyte by optimizing the iodide ion conductivity using a binary iodide salt and TiO2 nanofiller. The binary iodide salt system consists of K+ as the small cation and Pr4N+ as the large cation. The correlation between the efficiency variation and the short circuit current density variation with salt composition suggests that the improved iodide ion conductivity of the electrolyte plays a dominant role in enhancing the solar cell performance. The highest DSSC efficiency of 4.12% is obtained for the electrolyte with salt composition 25 wt% Pr4N+I−: 75wt.% KI. The incorporation of 2.5 wt% TiO2 nano fillers into the polymer electrolyte further enhances the solar cell efficiency to 5.31%, very likely due to the increased ionic mobility caused by the increased amorphous phase content of the PEO based polymer electrolyte.