Viable Alternative to N719 for Dye-Sensitized Solar Cells

A new synthetically facile heteroleptic ruthenium(II) sensitizer (NBu4)[Ru(4,7-dpp)(dcbpyH)(NCS)(2)], coded as YS5, where NBu4 is tetrabutylammonium, 4,7-dpp is 4,7-diphenyl-1,10-phenanthroline, and dcbpyH is the singly deprotonated surface anchoring derivative of 4,4'-dicarboxy-2,2'-bipyridine (dcbpyH(2)), was designed, synthesized, and incorporated into regenerative mesoscopic titania-based dye-sensitized solar cells. The sensitizer has characteristic broad, high extinction coefficient MLCT bands spanning the visible spectrum. The compound was fully characterized by 1D and 2D H-1 NMR, MALDI-TOF-MS, UV-vis, photoluminescence, Raman, IR, and electrochemistry. YS5 exhibits strong visible absorption properties with a molar extinction coefficient of 1.71 x 10(4) M-1 cm(-1) at its 522 nm maximum. In operational liquid junction-based DSSCs under simulated AM 1.5G one-sun excitation (100 mW/cm(2)), the photovoltaic performance of YS5 compares almost equally against the current benchmark sensitizer N719 in side-by-side comparisons, producing a power conversion efficiency of 6.05% with a maximum IPCE of 65% at 540 nm. The data presented in this manuscript strongly suggest that YS5 is indeed a viable sensitizer for nanocrystalline TiO2-based DSSCs, seemingly poised for widespread adaptation.