An efficient organogelator for ionic liquids to prepare stable quasi-solid-state dye-sensitized solar cells

Abstract

A low molecular weight amphiphilic organogelator capable of forming intermolecular hydrogen bonds and well-organized supramolecular structures was found to efficiently gel low-viscosity binary mixtures of ionic liquids at low concentrations. With this gelator it is possible to prepare stable quasi-solid-state dye-sensitized solar cells (DSCs). At a gelator concentration of only 2 wt%, the sol-gel transition temperature (Tgel) based on the lowest viscosity ionic liquid mixture was at 108 °C, well above the service temperature. Due to the thermoreversible nature of the system, the cells can be conveniently filled with a low-viscosity liquid. Upon cooling and formation of the gel a mechanically stable quasi-solid-state electrolyte was obtained. We successfully employed this quasi-solid ionic liquid electrolyte in DSCs and obtained an efficiency of 6.3% at full sunlight irradiation and maintained its stability during the light soaking accelerating stress test at 60 °C over 1000 h. © The Royal Society of Chemistry 2006.