A Heteroleptic Bis(tridentate) Ruthenium(II) Platform Featuring an Anionic 1,2,3-Triazolate-Based Ligand for Application in the Dye- Sensitized Solar Cell

A series of bis(tridentate) ruthenium(II) complexes featuring 2,2′:6′,2′′-terpyridine, functionalized with anchoring groups, and new anionic 1,2,3-triazolate-based tridentate ligands is presented. The title complexes are readily synthesized and can be decorated with alkyl chains, in order to improve the device stability and allow the use of alternative electrolytes, utilizing azide-alkyne cycloaddition methods. On account of the strong electron donation from the 1,2,3-triazolates, the complexes exhibit a broad metal-to-ligand-charge-transfer absorption (up to 700 nm) leading to an electron transfer towards the anchoring ligand. The lifetime of the charge-separated excited states are in the range of 50 -80 ns. In addition, the ground- and excited-state redox potentials are appropriate for the application in in dye-sensitized solar cells as demonstrated by power conversion efficiencies of up to 4.9% (vs. 6.1% for N749).