Cationic cetylpyridinium micelle as a novel electrolyte system for dye-sensitized solar cells

Abstract

The charge transfer process within the electrolyte system is an active area for further improving the conversion efficiency of the dye-sensitized solar cell (DSSC). In this work, micelle formed by cationic surfactant cetylpyridinium (CP) chloride was used in the electrolyte to enhance the ion transport of the redox couple. Using a mixed solvent of ethylene glycol and acetonitrile at 1:9 volume ratio and 0.50 M CP, an 83% improvement in DSSC efficiency was observed. Because of a strong correlation between the efficiency and the current density as a function of the CP concentration, the presence of CP micelle likely caused a favorable shift in the ion transport within the electrolyte. According to the cyclic voltammetry, such improved ion transport can be attributed to a faster diffusion of the redox couple, particularly the I3- diffusion. In addition, the impedance analysis also revealed a short electron lifetime for the diffusion process in the presence of the CP micelle. From these results, it is plausible that the CP micelle in the electrolyte provides an extensive network of positively-charged interfaces, which facilitates the diffusion of the redox couple and enhances the overall performance of the DSSC.