Click-Functionalized Ru(II) Complexes for Dye-Sensitized Solar Cells

Three heteroleptic ruthenium complexes incorporating new ancillary ligands synthesized by sequential connection of different alkyl functionalities with triazole as a linker are prepared using click chemistry. These sensitizers exhibit low-energy metal-to-ligand charge transfer bands centered at 540 nm with molar extinction coefficients of up to 1.54 x 10(4) L mol-1 cm-1. The devices using these sensitizers in conjunction with a volatile electrolyte show high photovoltaic conversion efficiencies of 8.7 to 9.9% under standard AM 1.5G sunlight (100 mW cm-2) conditions. Using an ionic liquid electrolyte, the cells show not only a good power-conversion efficiency of up to 7.1%, but also promising long-term stability under full sunlight intensity at 60 degrees C. The difference in the photovoltaic parameters during the ageing process is investigated by employing transient photoelectrical measurements.