Metal oxide nanostructures and quasi-solid electrolytes for dye-sensitized solar cells

The role of the nanostructured oxide in dye sensitized solar cell photoanode is crucial, towards the development of efficient photoelectrochemical solar harvesters. Several criteria, as the possibility to expose a wide surface for dye sensitization and a low recombination behavior during electron transport at the photoelectrode, have to be balanced in the optimization of the morphology of the nanostructured material for an efficient light capturing and charge transport at the photoelectrode. 1D or quasi 1D nanostructures can guarantee a fast and direct charge transport, but usually pay a lot in terms of surface area, being it significantly lower than in nanocrystalline network. Thus, material with a 3D branched nanomorphology with size and spacing on the order of the exciton diffusion length could represent the equilibrium point between the different requirements. Moreover, for the development of solar harvesters exploitable towards an industrial scale, such photoharvesting materials have to be combined with a solid or quasi-solid electrolyte that can guarantee high long-term stability. We will present our recent results on the development of different metal oxide nanostructures (e.g. TiO2 nanotubes and spongelike ZnO) in the fabrication of efficient DSC photoanodes. Particular emphasis will be dedicated to the evaluation of the charge transport properties, showing the reduced charge recombination behavior with respect to standard TiO2 nanoparticle network. Moreover, the application of self standing acrylic-methacrylic membranes prepared by UV-curing as quasi-solid electrolytes will be reported. The evaluation of the photoelectrochemical, structural, and physicochemical characteristics of these electrolytes will be thoroughly discussed.