Artificial photosynthesis based on dye-sensitized nanocrystalline TiO2 solar cells

Abstract

A new series of amphiphilic heteroleptic ruthenium(II) sensitizers [Ru(H2dcbpy)(dhbpy)(NCS)2] (C1), [Ru(H2dcbpy)(bccbpy)(NCS)2] (C2), [Ru(H2dcbpy)(mpubpy)(NCS)2] (C3), [Ru(H2dcbpy)(bhcbpy)(NCS)2] (C4) 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 ≈80% incident photon-to-current efficiencies (IPCE). Under standard AM 1.5 sunlight, the C4 sensitizer gave 15 mA/cm2 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%. © 2007 Elsevier B.V. All rights reserved.