Spectral splitting photovoltaics using perovskite and wideband dye-sensitized solar cells

The extension of the light absorption of photovoltaics into the near-infrared region is important to increase the energy conversion efficiency. Although the progress of the lead halide perovskite solar cells is remarkable, and high conversion efficiency of >20% has been reached, their absorption limit on the long-wavelength side is similar to 800 nm. To further enhance the conversion efficiency of perovskite-based photovoltaics, a hybridized system with near-infrared photovoltaics is a useful approach. Here we report a panchromatic sensitizer, coded DX3, that exhibits a broad response into the near-infrared, up to similar to 1100 nm, and a photocurrent density exceeding 30 mA cm(-2) in simulated air mass 1.5 standard solar radiation. Using the DX3-based dye-sensitized solar cell in conjunction with a perovskite cell that harvests visible light, the hybridized mesoscopic photovoltaics achieved a conversion efficiency of 21.5% using a system of spectral splitting.open0

[Use of tobacco smoke: approach and risk perception by middle-school students in Catania (Italy)]

The aim of this study was to investigate the approach and behaviour of middle school students in Catania, towards the risks associated with tobacco smoke. This study is part of a multicentric project evaluating the lifestyles of middle school students (grades 6-8), carried out by the Research and Health Education Group (GRES) and was performed during the 2006/2007 school year. In total 432 students participated in the study by completing a self-administered questionnaire. Data was analysed by using the Statistical Package for the Social Sciences (SPSS). Results show an increasing trend in the number of smokers from grades 6 to 8. In grades 6 and 8 most smokers are female while in grade 7 male smokers outnumber female smokers. Three percent of the student population reports smoking occasionally and 3% are regular smokers. In light of these results families, schools and institutions should take charge of programming and implementing health promotion interventions aimed at reducing risks and improving the quality of life of students in Catania

Sensitization of TiO2 with ruthenium complexes containing boronic acid functions.

New ruthenium complexes based on bipyiridine and terpyridyne type ligands, containing boronic acid functions, of formulae: [Ru(bpy-OB(OH)(2))(2)(CN)(2)], 6, (bpy-Phi-B(OH)(2) = 4-(2,2'-dipyridil)phenylboronic acid), [Ru(trpy-B(OH)(2))(tb(2)bpy)Cl](PF6), 11, (trey-B(OH)(2) = 4-[4'-(2,2':6',2"-terpyridil]-boronic acid), [Ru(trpy)-Phi-B(OH)(2))(tb(2)bpy)Cl] (PF6), 12, (trey)-Phi-B(OH)(2) = 4-[4'-(2,2':6',2"-terpyridil]phenylboronic acid), have been prepared, characterized, and tested in dye-sensitized solar cells (DSSCs). The results of this first study indicate that: (i) the boronic acid function acts as interlocking group between sensitizer and mesoporous titanium dioxide; (ii) only the presence of two B(OH)(2) groups/molecule allow to obtain high photoanode surface coverages with optical densities > 1; (iii) The presence of the phenyl spacer in 12 reduces the photocurrent efficiency with respect to complex 11, most probably for a reduced electronic coupling between excited sensitizer and semiconductor conduction band. The insights gained from this work suggest that better photoelectrochemical performances should be obtained with dye molecules based on bpy type ligands bearing two boronic acid functions directly bound to the aromatic ring

Sensitization of nanocrystalline TiO2 with black absorbers based on Os and Ru polypyridine complexes.

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What is the best anchoring group for a dye in a dye-sensitized solar cell?

We developed a computational procedure to screen many different anchoring groups used or usable to connect a dye to the semiconducting surface in a dye-sensitized solar cell. The procedure leads to a clear identification of the anchoring groups that bind strongly to the surface and facilitate the electron injection at the same time, providing clear-cut indications for the design of new dyes. The complicated interplay of factors that determine the final results (preferred adsorption mode, the anchor’s effect on the dye’s electronic structure, and dye–semiconductor coupling) is illustrated through a few examples showing how chemical intuition can often be misleading in this problem