"Click-chemistry" approach in the design of 1,2,3-triazolyl-pyridine ligands and their Ru(II)-complexes for dye-sensitized solar cells

The synthesis of new 1,2,3-triazolyl-pyridine ligands via "click-chemistry" and their corresponding Ru(L)(2,2'-bipyridyl-4,4'-dicarboxylic acid)(NCS)(2) complexes (L = 1,2,3-triazolyl-pyridine) are presented. The complexes have been photophysically and electrochemically characterized and have been used as sensitizers in dye-sensitized solar cells (DSSC). In DSSCs with an acetonitrile-based electrolyte the cells comprising of Ru(2-(1-(4-hexylphenyl)-1H-1,2,3-triazol-4-yl)pyridine)(2,2'-bipyridyl- 4,4'-dicarboxylic acid)(NCS)(2) TBA salt 1 showed an overall power conversion efficiency of 7.8% under full sunlight intensity, and Ru(2-(4-(4-hexylphenyl)-1H-1,2,3-triazol-1-yl)pyridine)(2,2'-bipyridyl- 4,4'-dicarboxylic acid)(NCS)(2) TBA salt 2 an efficiency of 4.7%. Transient photovoltage and photocurrent decay measurements showed an enhanced performance for dye 1 due to faster electron transport into the TiO2 film and lower recombination rate in comparison to dye 2 sensitized devices. Additionally, solid-state devices were prepared with 2 mm thick TiO2 films using spiro-OMeTAD as a hole-transport material. The solid-state dye-sensitized solar cells showed power conversion efficiencies of 1.92% and 0.38% for sensitizer 1 and 2, respectively.