Details

Autor(en) / Beteiligte

• Raber, McKenzie M
• Brady, Matthew D
• Troian-Gautier, Ludovic
• Dickenson, John C
• Marquard, Seth L
• Hyde, Jacob T
• Lopez, Santiago J
• Meyer, Gerald J
• Meyer, Thomas J
• Harrison, Daniel P

Titel

Fundamental Factors Impacting the Stability of Phosphonate-Derivatized Ruthenium Polypyridyl Sensitizers Adsorbed on Metal Oxide Surfaces

Ist Teil von

• ACS applied materials & interfaces, 2018-07, Vol.10 (26), p.22821-22833

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2018

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• A series of 18 ruthenium­(II) polypyridyl complexes were synthesized and evaluated under electrochemically oxidative conditions, which generates the Ru­(III) oxidation state and mimics the harsh conditions experienced during the kinetically limited regime that can occur in dye-sensitized solar cells (DSSCs) and dye-sensitized photo-electrosynthesis cells, to further develop fundamental insights into the factors governing molecular sensitizer surface stability in aqueous 0.1 M HClO4. Both desorption and oxidatively induced ligand substitution were observed on planar fluorine-doped tin oxide (FTO) electrodes, with a dependence on the E 1/2 Ru­(III/II) redox potential dictating the comparative ratios of the processes. Complexes such as RuP4OMe (E 1/2 = 0.91 vs Ag/AgCl) displayed virtually only desorption, while complexes such as RuPbpz (E 1/2 > 1.62 V vs Ag/AgCl) displayed only chemical decomposition. Comparing isomers of 4,4′- and 5,5′-disubstituted-2,2′-bipyridine ancillary ligands, a dramatic increase in the rate of desorption of the Ru­(III) complexes was observed for the 5,5′-ligands. Nanoscopic indium-doped tin oxide thin films (nanoITO) were also sensitized and analyzed with cyclic voltammetry, UV–vis absorption spectroscopy, and X-ray photoelectron spectroscopy, allowing for further distinction of desorption versus ligand-substitution processes. Desorption loss to bulk solution associated with the planar surface of FTO is essentially non-existent on nanoITO, where both desorption and ligand substitution are shut down with RuP4OMe. These results revealed that minimizing time spent in the oxidized form, incorporating electron-donating groups, maximizing hydrophobicity, and minimizing molecular bulk near the adsorbed ligand are critical to optimizing the performance of ruthenium­(II) polypyridyl complexes in dye-sensitized devices.