Novel Ru-based sunlight harvesters bearing dithienylpyrrolo (DTP)-bipyridine ligands: Synthesis, characterization and photovoltaic properties

Bipyridine bearing pi-delocalized dithienypyrrole moieties (DTP) have been involved as ligands (L) in the preparation of RuL2(dcbpy)(2+) and RuL(dcbpy)(NCS)(2) dyes. These dyes exhibited wide absorption domains in solution and when adsorbed on TiO2 photoanodes, light harvesting was found to be excellent (absorbance>1 in the 350-600 nm range). Careful investigations, combining transient spectroscopy and ab initio computations evidenced the capture of the photoexcited electron by low lying orbitals centred on the DTP moiety thus limiting the efficiency in DSSC despite favourable redox potentials for both injection and ground state regeneration. (C) 2013 Elsevier Ltd. All rights reserved.