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Nanocrystalline C-doped TiO2 hybrid hollow spheres were prepared by solvothermal synthesis by controlling calcinations of mixtures of furfural, chitosan or saccharose with titanium isopropoxide. The origin of the carbon influences the texture, the crystalline framework, and the optical and photoelectrochemistry properties of the TiO2. The results indicate that the carbon–TiO2 hybrid hollow spheres may be used as TiO2-based film electrodes for use in solar cells., J. Matos thanks to the authorities of the Venezuelan Institute for Scientific Research (IVIC) for the permission given to perform the sabbatical year at the ITQ-UPV in Valencia, Spain. J.C. Hernandez-Garrido acknowledges financial support from MICINN/FEDER NANOLANCAT Project (Ref: MAT2008-00889-NAN).

Two series of novel ruthenium bipyridyl dyes incorporating sulfur-donor bidentate ligands with general formula [Ru(R-bpy)2C2N2S2] and [Ru(R-bpy)2(S2COEt)][NO3] (where R=H, CO2Et, CO2H; C2N2S2 = cyanodithioimidocarbonate and S2COEt = ethyl xanthogenate) have been synthesized and characterized spectroscopically. electrochemically and computationally. The acid derivatives in both series C2N2S2 3 and S2COEt 6) were used as a photosensitizer in a dye-sensitized solar cell (DSSC) and the incident photo-to-current conversion efficiency (IPCE), overall efficiency (η) and kinetics of the dye/TiO2 system were investigated. It was found that 6 gave a higher efficiency cell than 3 despite the latter dye's more favorable electronic properties, such as greater absorption range, higher molar extinction coefficient and large degree of delocalization of the HOMO. The transient absorption spectroscopy studies revealed that the recombination kinetics of 3 were unexpectedly fast, which was attributed to the terminal CN on the ligand binding to the TiO2, as evidenced by an absorption study of R = H and CO2Et dyes sensitized on TiO2. and hence leading to a lower efficiency DSSC.

New composite PEO-based polymer-gel electrolytes were developed, using propylene carbonate (PC) plasticizer and iodide/triiodide (I-/I-3(-)) redox couple. The iodide anion was introduced in the form of the corresponding metal salts: CsI, RbI and LiI and the influence of the metal cation was examined. The non-volatile and high polar character of the PC plasticizer results to excellent ionic conductivity values of the electrolyte samples (up to 1.6 mS cm(-1)), as well as remarkable stability over time. Linear sweep voltametry measurements revealed noticeable triiodide diffusion coefficient values (in the order of 2 x 10(-6) cm s(-1)). The thermograms confirm the amorphicity of the electrolytes (crystallinity values below 20%). All the experimental results showed that the introduction of inorganic titania filler (Degussa P25) into the polymer matrix reduces even more the crystallinity of the samples and enhances the mobility of the redox couple. Nanocrystalline photoelectrochemical solar cells were fabricated with the newly developed composite electrolytes and were tested with I-V measurements. All cells presented high efficiency values for this type of composite electrolytes, with the best performance attained in the case of the PEO-TiO2-PC(CSI/I-3(-)) electrolyte, with overall energy conversion efficiency (eta) of 2.87% under standard AM1.5 simulated solar irradiation. Our results clearly support the redox couple mobility dependence on the cation nature. (C) 2007 Elsevier B.V. All rights reserved. Journal of Photochemistry and Photobiology a-Chemistry

We report using doctor-blading to replace conventional spin coating for the deposition of the hole-transport material spiro-OMeTAD (2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene) in solid-state dye-sensitized solar cells. Doctor-blading is a roll-to-roll compatible, large-area coating technique, is capable of achieving the same spiro-OMeTAD pore filling fraction as spin coating, and uses much less material. The average power conversion efficiency of solid-state dye-sensitized solar cells made from doctor-blading is 3.0% for 2-mu m thick films and 2.0% for 5-mu m thick films, on par with devices made with spin coating. Directions to further improve the filling fraction are also suggested. (c) 2010 Elsevier B.V. All rights reserved.