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High Extinction Coefficient Ru-Sensitizers that Promote Hole Transfer on Nanocrystalline TiO2

Maria Abrahamsson (Institutionen för kemi- och bioteknik, Fysikalisk kemi) ; Joachim Hedberg (Institutionen för kemi- och bioteknik, Fysikalisk kemi) ; H. C. Becker ; A. Staniszewski ; W. H. Pearson ; W. B. Heuer ; G. J. Meyer
Chemphyschem (1439-4235). Vol. 15 (2014), 6, p. 1154-1163.
[Artikel, refereegranskad vetenskaplig]

Two series of Ru-II polypyridyl compounds with formulas [(bpy)(2)RuL](PF6)(2) and [(deeb)(2)RuL](PF6)(2), where bpy is 2,2-bipyridine, deeb is 4,4-diethylester-2,2-bpy, and L is one of several substituted 9-(1,3-dithiole-2-ylidene)-4,5-diazafluorene ligands, were studied as potential photosensitizers for TiO2. These compounds possess notably high extinction coefficients (40000M(-1)cm(-1) @470 nm) which are shown by time-dependent density functional theory (TD-DFT) calculations to result from overlapping metal-to-ligand charge transfer (MLCT) and ligand-localized transitions. Low-temperature absorption and photoluminescence measurements were suggestive of a short-lived MLCT excited state. When adsorbed onto TiO2 thin films, both the free ligands (L) and their corresponding [(deeb)(2)RuL](2+) complexes exhibited rapid excited-state electron injection into TiO2; in the case of the complexes, this was followed by rapid (k>10(8) s(-1)) hole transfer from Ru-III to the 1,3-dithiole ring of the L ligand. Observation of diffusion-limited reductive quenching of the [Ru(bpz)(3)](2+)* (bpz is 2,2-bipyrazine) excited state by the L ligands in solution supported the occurrence of intramolecular hole transfer following electron injection by the TiO2-anchored complexes.

Nyckelord: charge transfer, dye-sensitized solar cells, extinction coefficients, hole transfer, Ruthenium, I-I BONDS, RUTHENIUM(II) COMPLEXES, SOLAR-CELLS, ELECTRON-TRANSFER, METAL-COMPLEXES, EXCITED-STATES, PHOTOPHYSICAL PROPERTIES, THIN-FILM, LIGANDS, ELECTROCHEMISTRY, EGAN B, 1991, NATURE, V353, P737

Denna post skapades 2014-06-13. Senast ändrad 2017-09-14.
CPL Pubid: 199171


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Institutionen för kemi- och bioteknik, Fysikalisk kemi (2005-2014)



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Structure-Function Relationships in RuII Complexes with Unconventional Ligands: Photophysical and Photochemical Studies