Ruthenium dyes bipyridyl

Fig. 7) for example measurement of tris(l,10-phenanthroline)cobalt(II/III) show that this redox couple is 230 mV deeper (more positive redox potential) than iodide electrolyte [37]. As a consequence, cobalt electrolytes, and soUd organic hole conductors, have been widely explored. It should be noticed in Fig. 7 that Co(II/III) redox couple stands too deep to regenerate oxidized standard ruthenium bipyridyl dye. Therefore both the dye and the redox couple have been simultaneously optimized for strong performance [99, 100] and this approach has provided large rewards in terms of power conversion efficiency [2]. 

The dye sensitised semi-conductor electrode is a transparent conducting sheet of glass coated (5 pm) with nanocrystalline TiOj (diameter 20 nm) doped with a ruthenium bipyridyl complex. The dye absorbs light, becomes excited and injects electrons into the TiOj electrode. The electrons travel into the transparent WO3 hhn and then, to balance the charge, lithium ions from the electrolyte solution insert into the WO3 and in so doing create the coloured species as described above. If the light source is removed then the cell is bleached back to its original colour. However, if the... 

Ruthenium bipyridyl complexes are suitable photosensitizers because then-excited states have a long lifetime and the oxidized Ru(III) center has a longterm chemical stability. Therefore, Ru bipyridyl complexes have been studied intensively as photosensitizers for homogeneous photocatalytic reactions and dye-sensitization systems. The Ru bipyridyl complex, bis(2,2 -bipyridine)(2,2 -bipyri-dine-4, 4,-dicarboxylate)ruthenium(II), having carboxyl groups as anchors to the semiconductor surface was synthesized and single-crystal Ti02 photoelectrodes sensitized by this Ru complex were studied in 1979 and 1980 [5,6]. 

Similarly in the case of organic solar cells, the low optical absorbance in the red/near-infrared region of the dyes commonly used in DSSCs such as ruthenium bipyridyl [276] has prompted the incorporation of Pcs in these devices [277,278],... 

Visible light soaking alone is not a dominant stress factor, which means that the dye (a ruthenium bipyridyl complex) used in these tests is surprisingly stable [7,18,19]. 

Tachibana Y., Hague S. A., Mercer I. P., Durrant J. R. and Klug D. R. (2000), Electron injection and recombination in dye-sensitized nanocrystalline titanium dioxide fdms a comparison of ruthenium bipyridyl and porphyrin sensitizer dyes , J. Phys. Ghent. B 104, 1198-1205. 

In the seminal Nature paper of 1991, O Regan and Gratzel reported an order-of-magnitude increase for DSSC type solar cell efficiency to 7-8%. ° With regards to stability, a turnover number of 5 x 10 was measured for the sensitiser (a trimeric ruthenium complex).This was followed up by the introduction of the ruthenium bipyridyl-based N3 dye (Figure 3.15), giving efficiencies around 10%. 

A dye which shows particular promise for this application is the octahedral ruthenium(n) complex of 2,2 -bipyridyl (234). While this type of system appears to offer considerable potential as a means of solar energy conversion, the efficiency of the technology, at its current state of development, is significantly lower than that of traditional silicon photocells. 

Dyes such as erythrosin B [172], eosin [173-177], rose bengal [178,179], rhodamines [180-185], cresyl violet [186-191], thionine [192], chlorophyll a and b [193-198], chlorophyllin [197,199], anthracene-9-carboxylate [200,201], perylene [202,203] 8-hydroxyquinoline [204], porphyrins [205], phthalocyanines [206,207], transition metal cyanides [208,209], Ru(bpy)32+ and its analogs [83,170,210-218], cyanines [169,219-226], squaraines [55,227-230], and phe-nylfluorone [231] which have high extinction coefficients in the visible, are often employed to extend the photoresponse of the semiconductor in photoelectro-chemical systems. Visible light sensitization of platinized Ti02 photocatalyst by surface-coated polymers derivatized with ruthenium tris(bipyridyl) complex has also been attempted [232,233]. Because the singlet excited state of these dyes is short lived it becomes essential to adsorb them on the semiconductor surface with... 

When rare-earth-metal ions such as Eu and Tb are bound to polyelectrolyte membranes such as poly(sodium acrylate) and poly(sodium ethene-sulphonate) their fluorescence intensities are considerably enhanced this is associated with the formation of asymmetric bonds between the rare-earth ions and the acrylate/S03 groups in the polymers. This was confirmed by the addition of EDTA to the Tb -poly(sodium acrylate) complex which, because of its preferential binding to the polymer, displaced Tb ions and resulted in reduced fluorescence of the latter. Stokes shifts of fluorescent dyes in different polymer systems have been related more to mobility effects in the polymer than polarity,and the fluorescence of hydrolysed aspirin has been found to be affected by the nature of different polymer supports.The luminescence properties of cis-(2,2 -bipyridyl)ruthenium(ii) complexes have been found to be influenced by binding the complex to a polymer matrix,as have the luminescence properties of flavones and l-octadecyl-3,3-dimethyl-6 -nitrospiro(indoline-2,2 -2H-benzopyran). Other studies of interest in-... 

Interest in cationic photopolymerisations has increased dramatically over the last year. Novel crown ether styryl dyes have been developed for 2+2 cycloaddition reactions while a tris(2,2 -bipyridyl)ruthenium complex has been successful in inducing the photopolymerisation of aniline. New hybrid vinyl... 

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