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A new ruthenium(II) complex, tetrabutylammonium [ruthenium (4-carboxylic acid-4'-carboxylate-2,2'-bipyridine)(4,4'-di(2-(3,6-dimethoxyphenyl)ethenyl)-2,2'-bipyridine)(NCS)(2)] (N945H), was synthesized and characterized by analytical, spectroscopic, and electrochemical techniques. The absorption spectrum of the N945H sensitizer is dominated by metal-to-ligand charge-transfer (MLCT) transitions in the visible region, with the lowest allowed MLCT bands appearing at 25 380 and 18 180 cm(-1). The molar extinction coefficients of these bands are 34 500 and 18 900 M(-1) cm(-1), respectively, and are significantly higher when compared to than those of the standard sensitizer cis-dithiocyanatobis(4,4'-dicarboxylic acid-2,2'-bipyridine)ruthenium(II). An INDO/S and density functional theory study of the electronic and optical properties of N945H and of N945 adsorbed on TiO(2) was performed. The calculations point out that the top three frontier-filled orbitals have essentially ruthenium 4d (t(2g) in the octahedral group) character with sizable contribution coming from the NCS ligand orbitals. Most critically the calculations reveal that, in the TiO(2)-bound N945 sensitizer, excitation directs charge into the carboxylbipyridine ligand bound to the TiO(2) surface. The photovoltaic data of the N945 sensitizer using an electrolyte containing 0.60 M butylmethylimidazolium iodide, 0.03 M I(2), 0.10 M guanidinium thiocyanate, and 0.50 M tert-butylpyridine in a mixture of acetonitrile and valeronitrile (volume ratio = 85:15) exhibited a short-circuit photocurrent density of 16.50 +/- 0.2 mA cm(-2), an open-circuit voltage of 790 +/- 30 mV, and a fill factor of 0.72 +/- 0.03, corresponding to an overall conversion efficiency of 9.6% under standard AM (air mass) 1.5 sunlight, and demonstrated a stable performance under light and heat soaking at 80 degrees C.

A new heteroleptic polypyridyl ruthenium complex (see Figure) with a high molar extinction coefficient has been synthesized. The complex is demonstrated to be a highly efficient, stable sensitizer for nanocrystalline dye-sensitized solar cells. For a newly developed dye, the achievement of 10.2 % power conversion efficiency is very encouraging.

A review of the research and development of dye-sensitized solar cells within the Swedish research program Angstrom Solar Center. A path towards low prodn. cost is the development of a continuous process, which allows the prodn. of solar cells in large vols. and with a high productivity. We have developed a deposition method for the prodn. of the mesoporous TiO2 electrode layer that is based on compression of a powder film at room temp. This technique allows us to use flexible substrates, a prerequisite for a continuous process. A novel interconnect technol., compatible with a continuous prodn. process, is described. Stability data of plastic dye-sensitized solar cells, exposed to indoor light for >10,000 h, demonstrates the possibility for the technol. to be explored for various types of indoor applications. Optimization of the dye-sensitized solar cells is a challenging task as it is a complex highly interacting mol. system. A system approach is proposed, where the complete dye-sensitized solar cells is investigated with a series of measurement techniques that allows the study of the internal processes under relevant conditions. Two examples of such techniques are given.

Four new ruthenium polypyridyl complexes with mono- or di-((2-thienyl) ethenyl) substituted bipyridines have been synthesized. The complexes were characterized by NMR, elemental analysis, UV–Vis absorption and electrochemistry (differential pulse and cyclic voltammetry). Electroactive polymer films of these complexes have been prepared by oxidative electropolymerisation and characterized by UV–Vis absorption spectroscopy and electrochemistry. The electrochemically induced polymerisation of the complexes resulted in a significant shift of the oxidation potential of the Ru(II)–Ru(III) process towards more positive potentials. Also, MLCT absorption band of the polymeric complexes is shifted towards shorter wavelengths. These results are interpreted in terms of an interruption of the conjugated system of the (2-thienyl)ethenyl-substituted bipyridine ligands due to a radical polymerisation mechanism affecting rather the ethenyl part of the ligand than the thienyl.

A comparison of the properties of the 2-thienyl-substituted carboxyphenyl {RuII(terpy)2} dyes with their non-substituted analogs has enabled us to gain insight into the electronic properties that are prerequisite for efficient electron injection into the TiO2 conduction band in photoelectrochem. solar cells. Introducing the thienyl group has a profound effect upon the efficiency of photoinduced electron injection. This effect can be explained by a significant shift in the LUMO position from the terpy ligand anchored on the TiO2 surface towards the 2-thienyl substituted ligand, which is shown by means of electrochem. and semi-empirical calcns.

Adsorption of phthalocyanines lacking conventional attaching substituents onto nanostructured TiO 2 electrodes has been studied, and some of the important factors for sensitisation have been identified. Tetra-dimethoxyphenyl phthalocyanine (2) and tetra-phenyl phthalocyanine (3), derived from 4-(2,5-dimethoxyphenyl)phthalonitrile and 4-phenylphthalonitrile, respectively, are shown to successfully sensitise nanostructured TiO 2 electrodes, with IPCE max of 9 and 5% at λ = 650 nm . The dye-oxide systems have been characterised by UV-vis spectroscopy, cyclic voltammetry and photoelectrochemical methods, and the dye–surface interactions are discussed.

A number of new ruthenium polypyridyl complexes with mono- or di-(3-methoxystyryl) substituted bipyridines have been synthesized. The complexes were characterised by NMR, elemental analysis, UV-vis absorption and emission spectroscopy, and cyclic voltammetry. Electroactive polymer films of these complexes have been prepared both by oxidative and reductive electropolymerisation. The polymers have been characterised by UV-vis absorption spectroscopy and cyclic voltammetry. Possible processes involved in the polymerisation and the structure of the film are discussed.

The substituted phthalonitriles 4-phenylphthalonitrile (2a), 4-(2,5-dimethoxyphenyl) phthalonitrile(2b) and 2-(3,4-dicyanophenyl)-4-methylpyridine(2c) have been prepared in good yields from 4-iodop ...

The new dye complex bis[4,4′-di(2-(3-methoxyphenyl)ethenyl)-2,2′-bipyridine][4,4′-dicarboxy-2,2′-bipyridine]ruthenium(II) dihexafluorophosphate (1) has been prepared, characterised by absorption spectroscopy and adsorbed onto nanocrystalline TiO2 electrodes. The resulting system was studied by absorption spectroscopy, electrochemistry and photoelectrochemistry and the results were compared to those for a reference system with bis[2,2′-bipyridine][4,4′-dicarboxy-2,2′-bipyridine]ruthenium(II) (2). The system with 1 displays a broader and red-shifted UV-vis absorption compared to that with 2. Moreover, the system with 1 is less sensitive towards the water content in the electrolyte, and an adsorbed monolayer of 1 remains on the electrode surface after days even in aqueous NaOH (0.1 M), while 2 desorbs immediately.

Methods for the prepn. and purifn. of new carboxylated 2,2'-bipyridine ligands, two of which contain the new anchoring functionality malonate, and a reliable method for the synthesis of the corresponding [Ru(bpy)2(L)](PF6)2 complexes are described. Their suitability for fundamental studies of the processes in wet solar cell applications has been investigated. All complexes show stable voltammograms in acetonitrile soln. and although the complexes were obtained as lithium carboxylate salts, they were sol. in non-polar org. solvents such as dichloromethane, which allowed for good reproducibility in the dye-coating step.The electrochem. and photoelectrochem. properties of dye-TiO2 systems are discussed. The photoelectrochem. properties in monochromatic and white light are related to the attaching group that is varied in the series of complexes: A formally non-conjugated malonate group as anchoring group generally gives similar results to that of a conjugated carboxylic group, the second carboxylate compensating the absence of conjugation. Also, the complexes with malonate as attaching group are more efficient than a complex with a non-conjugated carboxylic group, esp. in the red part of the action spectrum.The redox behavior of the adsorbed complexes is reversible at neg. potentials and quasi-reversible at pos. potentials. The latter feature is esp. interesting since it is possible to electrochem. oxidize the surface-attached ruthenium complexes even at potentials in the mid-bandgap region of the metal oxide film.