Pag. 5General criteria used in the preparation of Tables, Figures and Schemes.

Organic photovoltaic (OPV) devices, in particular polymer solar cells, made by solution processed organic materials have shown great promise as a disruptive technology for affordable electricity. Even though recent advances look impressive on paper, until now the commercialization of OPV has been hampered by the difficulty of converting lab produced "champion" cell figures into reliable industrial-scale product performances. A key factor to achieve this condition is to develop OPV materials (polymer donors, acceptors, buffer materials, electrodes materials and encapsulants) exhibiting the required technical and economic characteristics to be conveniently used in an industrial environment. The well established strategies for the design of materials for efficient lab-scale OPV devices are not sufficient when largearea printed panels are concerned. A number of additional requirements, normally not addressed in the laboratory context, must be met: the materials must be easily accessible as pure compounds in few synthetic steps from cheap starting compounds, need to be stable and soluble enough to afford ink formulations processable with roll-to-roll compatible equipment; solvent and solvent additives should be easily removable after printing, and possibly should be environmentally friendly compounds; the layers should achieve a stable morphology under mild conditions (low temperatures and short times); the above mentioned materials can be screened on glass substrates, but should be finally tested on plastic films, protected through a scalable encapsulation technique. The more researchers adhere to these guidelines, the greater the possibility for OPV to demonstrate at last its enormous potential on the industrial scale. Broader contextThe global electric energy demand in 2010 was about 21 400 TW h (source: IEA). Renewable energies accounted for almost one-h of the total energy production. While solar energy was only around 1% of this portion, over the past ve years it has averaged an annual growth rate of over 50%. Growth has been mostly concentrated in a few countries, where PV generates today a few percent of total yearly electricity production. High cost, along with the intermittency of the solar radiation, is one of the main limiting factors, therefore much effort must be spent to overcome these problems. Polymer-based organic solar cells have the potential to be cost-effective and lightweight solar energy converters, with a promising energy balance. Their function is based on the photoinduced electron transfer from a polymeric donor to an acceptor, generally a fullerene derivative. In principle, they can be fabricated by low temperature printing or coating processes from solvent-based inks, which are compatible with exible plastic substrates. Fair power conversion efficiencies ($10%), comparable with amorphous silicon, have been recently achieved in the laboratory, by the combination of improved materials engineering, ne control of the photoactive layer morphology and use of more sophisticated device archit...

Bequeme Routine: Mehrlagige dünne Polymerfilme wurden durch Elektrophorese auf in Agarose immobilisierten Partikeln angeordnet. Anschließendes Entfernen des Kerns führte zu robusten Kapseln mit unterschiedlichen Polymerzusammensetzungen (siehe Fluoreszenzbild). Dieser Ansatz ermöglicht den vielseitigen und routinemäßigen Aufbau von nano‐ und mikroskaligen Kapseln sowie beschichteten Partikeln in sehr wenigen Prozessschritten.

An experimental study of the rheological behaviour of three natural pyroclastic soils with different depositional processes remixed with water was carried out with the help of a rotational rheometer and inclined plane tests. A homogeneous fluid-like behaviour is obtained only within a very narrow range of concentrations, typically not more than 10%. Below this range the material sedimentates rapidly; above this range it behaves like a solid. In the fluid-like range the typical rheological behaviour of these suspensions is that of a yield stress fluid exhibiting a static yield stress larger than its dynamic yield stress. This effect probably finds its origin in a ‘local’ sedimentation effect: that is, the particles sedimentate just as necessary to form a structure more jammed than the structure during flow. As a result the flow of such materials is usually unstable: they will start to flow beyond a critical stress, but just beyond this value will reach a high shear rate associated with a high flowing velocity. The static and dynamic yield stresses of these materials increase widely from very low to very large values (several orders of magnitude). Inclined-plane tests were shown to provide reasonable although still approximate values for the static and dynamic yield stresses. These results suggest that in the field a small change in solid fraction will cause a slight decrease of the static yield stress, readily inducing a rapid flow that will stop only when the dynamic yield stress is reached, namely on a much smoother slope. This can explain the in situ observed post-failure behaviour of pyroclastic debris flows, which are able to flow over very long distances, even on smooth slopes

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