Artificial photosynthesis based on dye-sensitized nanocrystalline TiO2 solar cells

A new series of amphiphilic heteroleptic ruthenium(II) sensitizers [Ru(H(2)dcbpy)(dhbpy)(NCS)(2)] (C1), [Ru(H(2)dcbpy)(bccbpy)(NCS)(2)] (C-2), [Ru(H(2)dcbpy)(mpubpy)(NCS)(2)] (C-3), [Ru(H(2)dcbpy)(bhcbpy)(NCS)(2)] (C-4) have been synthesized and fully characterized by UV Vis, emission, NMR and cyclic voltammetric studies (where dhbpy = 4,4'-dihexyl-2,2'-bipyridine, bccbpy = 4,4'-bis(cholesteroxycarbonyl)2,2'-bipyridine, mpubpy = 4-methyl-4'-perfluoro-1H, 1H, 2H, 2H, 3H, 3H-undecyl-2,2'-bipyridine, bhcbpy = 4,4'-Bis(hexylcarboxamido)2,2'-bipyridine). The amphiphilic amide heteroleptic ruthenium(II) sensitizers, self-assembled on TiO2 surface from ethanol solution, reveal efficient sensitization in the visible window range yielding approximate to 80% incident photon-to-current efficiencies (IPCE). Under standard AM 1.5 sunlight, the C4 sensitizer gave 15 mA/cm(2) short circuit photocurrent density, 0.66 fill factor and an open circuit voltage of 0.75 V, corresponding to an overall conversion efficiency of 7.4%. (c) 2007 Elsevier B.V. All rights reserved.