Design and synthesis of heteroleptic ruthenium (II) complexes and their applications in nanocrystalline TiO 2 solar cells

Two ruthenium complexes, [Ru II(L2)(dcbpy)(NCS) 2] Ru II(4,5-diazafluoren-9-one)(4,4 '-dicarboxy-2,2 '-bipyridyl)-di(thiocyanate) [K30] and [Ru(dcbpy) 3] Ru IItris(4,4'-dicarboxy-2,2'-bipyridyl) [K303] have been synthesized and used in dye sensitized solar cells. The ruthenium complexes have been characterized by elemental analyses, FT-IR, UV-Vis, cyclic voltammetry and 1H NMR spectral methods. The performance of this complexes as charge transfer photosensitizer in nc-TiO 2 based dye sensitized solar cells is studied under standard AM 1.5 sunlight and by using an electrolyte consisting of 0.6 M N-methyl-N-butyl imidazolium iodide (BMII), 0.1 M LiI, 0.05 M I 2, 0.5 M 4-tert-butyl pyridine (TBP) in acetonitrile. Notably, the photo-to-electrical conversion efficiency of the DSSCs sensitized with [K30] and [K303] reaches 3.45%, and 6.33%, and the DSSC sensitized with [K303] shows better photovoltaic performances (Jsc = 19.58 mA/cm 2, Voc = 570 mV and FF = 0.58) than [K30]. © 2012 Elsevier B.V. All rights reserved.