Wang, P., Zakeerruddin, S.M., Grätzel, M., Kantlehner, W., Mezger, J., Stoyanov, E.V., and Scherr, O.
A novel family of room temperature ionic liquids, N,N-diethyl-N[sup ′],N[sup ′]-dipropyl-N[sup ′′]-hexyl-N[sup ′′]-methylguanidinium iodide (SGI) and N,N,N[sup ′],N[sup ′]-tetramethyl-N[sup ′′],N[sup ′′]-dipentylguanidinium tricyanomethanide (SGTM) were designed and synthesized. Due to the strong charge delocalization on the tricyanomethanide 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/cm[sup 2]. [ABSTRACT FROM AUTHOR]