High Extinction Coefficient Ru-Sensitizers that Promote Hole Transfer on Nanocrystalline TiO2
Artikel i vetenskaplig tidskrift, 2014

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.

THIN-FILM

dye-sensitized solar cells

ELECTRON-TRANSFER

NATURE

1991

EGAN B

P737

hole transfer

Ruthenium

RUTHENIUM(II) COMPLEXES

V353

I-I BONDS

EXCITED-STATES

ELECTROCHEMISTRY

PHOTOPHYSICAL PROPERTIES

METAL-COMPLEXES

SOLAR-CELLS

charge transfer

LIGANDS

extinction coefficients

Författare

Maria Abrahamsson

Chalmers, Kemi- och bioteknik, Fysikalisk kemi

Joachim Wallenstein

Chalmers, Kemi- och bioteknik, Fysikalisk kemi

Hans-Christian Becker

Uppsala universitet

A. Staniszewski

Johns Hopkins University

W. H. Pearson

US Naval Academy

W. B. Heuer

US Naval Academy

G. J. Meyer

Johns Hopkins University

ChemPhysChem

1439-4235 (ISSN) 1439-7641 (eISSN)

Vol. 15 1154-1163

Ämneskategorier

Kemi

DOI

10.1002/cphc.201301193