Stepwise assembly of amphiphilic ruthenium sensitizers and their applications in dye-sensitized solar cell

A novel synthetic route for preparation of amphiphilic heteroleptic ruthenium(II) complexes of the type [Ru(H(2)dcbpy)Cl(cymene)]NO3 (1) [Ru(H(2)dcbpy)(dmbpy)(NCS)(2)] (2), [Ru(H(2)dcbpy)(dhbpy)(NCS)(2)] (3) [Ru(H(2)dcbpy)(dnbpy)(NCS)(2)] (4) and [Ru(H(2)dcbpy)(dtdbpy)(NCS)(2)] (5) have been developed starting from dichloro(p-cymene)ruthenium(II) dimer. The performance of these complexes as charge-transfer photosensitizers in nanocrystalline TiO2-based solar cells was studied. When anchored complexes 2-5 onto a 12 + 4 mum thick nanocrystalline TiO2 films achieve very efficient sensitization over 85 +/- 5% incident photon-to-current efficiencies (IPCEs) in the visible region. Under standard AM 1.5 sunlight, using an electrolyte consisting of 0.6 M BMII; 0.05 M I-2; 0.1 M Lil; 0.5 M tert-butyl pyridine in 1:1 acetonitrile + valeronitrile the films yielded a short circuit photocurrent density of 16 +/- 0.5 mA/cm(2) and the open circuit voltage was 700 +/- 50 mV and a fill factor of 0.75 +/- 0.05, corresponding to an overall conversion efficiency of 8.6%. Solar cells based on amphiphilic sensitizers show remarkable stability under both thermal stress and light soaking matching the durability criteria applied to silicon solar cells for outdoor applications. (C) 2004 Elsevier B.V. All rights reserved.