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A novel counter electrode (CE) based on a silver and copper oxide nanocomposite is developed and characterized by XRD and FE-SEM. A polymeric system containing poly(3,4-ethylenedioxythiophene) (PEDOT) is employed as the conductive polymer to prepare a transparent CE for a dye-sensitized solar cell (DSSC) device. Electrochemical analysis is used to study the catalytic activity of the reduction of triiodide ions in different DSSC-based CEs. To study the effect of photoelectrode modification on charge-transfer resistance, alternating current impedance spectroscopy is carried out. Power conversion efficiency and short-circuit current density ($J_{\mathrm{SC}}$) increase from 8.01% to 9.06% and 16.18 to 17.79 mA/cm2, respectively, due to the significantly improved electrical conductivity and electrocatalytic activity of the novel PEDOT/Ag–CuO nanocomposite-based CE.

The row extract of ethanol soluble compounds from the green alga Enteromorpha intestinalis was used as source for chlorophyll pigments in the sensitization and co-sensitization of TiO2-based Dye Sensitized Solar Cells (DSSCs). We used two techniques for co-sensitization (the successive adsorptions of dyes, respective the cocktails of dyes) and the characteristics of DSSCs were studied having in view different pHs of the extracts. The results for DSSCs based on co-sensitized TiO2 photoanodes, obtained in diverse pH conditions, were compared with those for DSSCs based on substrates sensitized by a single source of pigments. The DSSCs fabricated using photoanodes sensitized with a cocktail of green seaweeds and red cabbage extracts, in basic medium, have higher value for efficiency, compared to green seaweeds, respective red cabbage extracts in the same conditions, and the fill factor was remarkable high (0.795). Thus, the co-sensitization by cocktail method may be a proper technique to enhance the light harvesting capability of natural dyes based DSSCs.

Through millions of years of evolution, Nature has accomplished the development of highly efficient and sustainable processes and the idea to understand and copy natural strategies is therefore very appealing. However, in spite of intense experimental and computational research, it has turned out to be a difficult task to design efficient biomimetic systems. Here we discuss a novel strategy for the computational design of biomimetic compounds and processes that consists of i) target selection; ii) atomistic and electronic characterization of the wild type system and the biomimetic compounds; iii) identification of key descriptors through feature selection iv) choice of biomimetic template and v) efficient search of chemical and sequence space for optimization of the biomimetic system. As a proof-of-principles study, this general approach is illustrated for the computational design of a 'green' catalyst mimicking the action of the zinc metalloenzyme Human Carbonic Anhydrase (HCA). HCA is a natural model for CO2 fixation since the enzyme is able to convert CO2 into bicarbonate. Very recently, a weakly active HCA mimic based on a trihelical peptide bundle was synthetized. We have used quantum mechanical/molecular mechanical (QM/MM) Car-Parrinello simulations to study the mechanisms of action of HCA and its peptidic mimic and employed the obtained information to guide the design of improved biomimetic analogues. Applying a genetic algorithm based optimization procedure, we were able to re-engineer and optimize the biomimetic system towards its natural counter part. In a second example, we discuss a similar strategy for the design of biomimetic sensitizers for use in dye-sensitized solar cells.

As a world first, 300 m² of dye-sensitized solar cells will be integrated into the facade of the EPFL's Convention Center. This prototype will constitute the first application of such technology to a public building. The translucent panels are constructed and assembled by local small and medium businesses and make use of an invention by EPFL researcher Michael Grätzel. This project is embedded within the framework of the partnership established in 2009 between EPFL and Romande Energie – whose aim is to create one of the largest solar energy parks in Switzerland.

Titania nanofibers were fabricated using the industrial NanospiderTM technology. The preparative protocol was optimized by screening various precursor materials to get pure anatase nanofibers. Composite films were prepared by mixing a commercial paste of nanocrystalline anatase particles with the electrospun nanofibers, which were shortened by milling. The composite films were sensitized by Ru-bipyridine dye (coded C106) and the solar conversion efficiency was tested in a dye-sensitized solar cell filled with iodide-based electrolyte solution (coded Z960). The solar conversion efficiency of a solar cell with the optimized composite electrode (? = 7.53% at AM 1.5 irradiation) outperforms that of a solar cell with pure nanoparticle film (? = 5.44%). Still larger improvement was found for lower light intensities. At 10% sun illumination, the best composite electrode showed ? = 7.04%, referenced to that of pure nanoparticle film (? = 4.69%). There are non-monotonic relations between the film's surface area, dye sorption capacity and solar performance of nanofiber-containing composite films, but the beneficial effect of the nanofiber morphology for enhancement of the solar efficiency has been demonstrated.

As one of the most important components in dye-sensitized solar cells (DSCs), photoanode materials have attracted massive interest and been greatly developed through the efforts of various research institutions in recent years. Photoanode materials not only provide a large surface for the sensitizer to favor charge separation, but also conduct the electrons to the collection electrode. In recent years, one-dimensional (1D) nanostructures (nanotubes (NT), nanowires (NW) and nanorods(NR)), which offer direct pathways for electron transport, and nanostructures (nanosheets (NS) and nanoparticles (NP)) with (001) crystal facets which possess higher surface energies have been widely employed as photoanode materials. In this review, the progress of 1D nanostructures and those with (001) crystal facets, as well as their photovoltaic performance in DSCs will be discussed briefly. Further efforts are needed to provide theoretical research for 1D and (001) facet nanostructured TiO2 and to improve DSC performances based on these photoanodes.

Dye-sensitized solar cells (DSCs) are one of the most promising environmental friendly and low material costs photovoltaic devices. DSCs accomplish the separation of the optical absorption and charge separation processes by the association of a sensitizer as light absorbing material with a wide band gap semiconductor. The mesoscopic morphology of the semiconductor produces an interface with a huge area endowing these systems with intriguing optoelectronic properties. In recent years the DSC has made excellent progress. Conversion efficiencies over 12% and excellent stability have been reached rendering it a credible alternative to conventional p-n junction photovoltaic devices. Commercial exploitation of DSCs started in 2009. In addition to the DSC, Laboratory of Photonics and Interfaces performs research in the field of photoelectrochemical water splitting and materials design for organic light emitting diodes.

Nanostructured liquid|solid and solid|solid bulk heterojunctions designed for the conversion of solar energy offer ideal models for the investigation of light-induced ET dynamics at surfaces. Despite significant study of processes leading to charge generation in third-generation solar cells, a conclusive picture of the photophysics of these photovoltaic converters is still missing. More specifically searched is the link between the molecular structure of the interface and the kinetics of surface photoredox reactions. Fundamental scientific issues in this field are addressed by there search project undertaken in the frame of the NCCR MUST endeavor, an outline of whic his given here.

Dye-sensitized solar cells (DSCs) are an emerging technology for the conversion of solar photons to electrical energy. Typical DSCs are based upon ruthenium complexes which act as photosensitizers for a wide band-gap semiconductor such as titanium dioxide. The low abundance of ruthenium raises issues about the sustainability of such devices. We now present promising prototype DSCs based upon copper(I) complexes.

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