Novel room temperature ionic liquids of hexaalkyl substituted guanidinium salts for dye-sensitized solar cells

Abstract

A novel family of room temperature ionic liquids, N, N-diethyl-N′ N′-dipropyl-N″-hexyl-N″-methylguanidinium iodide (SGI) and N, N, N′, N'′-tetramethyl-N″, N″-dipentylguanidinium tricyanomethanide (SGTM) were designed and synthesized. Due to the strong charge delocalization on the tri-cyanomethanide anion and, thus, weaker ion-pairing, SGTM has a lower viscosity than SGI salt that has iodide as an anion. SGI was successfully used as an iodide resource for dye-sensitized nanocrystalline solar cells. The device with a solvent-free, SGI-based electrolyte achieved a 5.9% power conversion efficiency under an air mass 1.5 incident light of 9.47 mW/cm2. © Springer-Verlag 2004.