The technology behind a large area array of flexible solar cells with a unique design and semitransparent blue appearance is presented. These modules are implemented in a solar tree installation at the German pavilion in the EXPO2015 in Milan/IT. The modules show power conversion efficiencies of 4.5% and are produced exclusively using standard printing techniques for large‐scale production.

Organotin impurities in product mixtures can be reduced from stoichiometric levels to approximately 15 parts per million by column chromatography using 10% w/w anhydrous potassium carbonate-silica as a stationary phase.

Homolytic aromatic substitution reactions are used for the efficient regioselective synthesis of helicenes, phenanthrenes, and azahelicenes. The use of halo and alkoxy substituents to control the stereochemical outcome of this approach and X‐ray studies of the resulting helicenes are described (see structure; red O, gray C).

The success of semiconducting organic materials has enabled green technologies for electronics, lighting, and photovoltaics. However, when blended together, these materials have also raised novel fundamental questions with respect to electronic, optical, and thermodynamic properties. This is particularly important for organic photovoltaic cells based on the bulk heterojunction. Here, the distribution of nanoscale domains plays a crucial role depending on the specific device structure. Hence, correlation of the aforementioned properties requires 3D nanoscale imaging of materials domains, which are embedded in a multilayer device. Such visualization has so far been elusive due to lack of contrast, insufficient signal, or resolution limits. In this Letter, we introduce spectral scanning transmission electron tomography for reconstruction of entire volume plasmon spectra from rod-shaped specimens. We provide 3D structural correlations and compositional mapping at a resolution of approximately 7 nm within advanced organic photovoltaic tandem cells. Novel insights that are obtained from quantitative 3D analyses reveal that efficiency loss upon thermal annealing can be attributed to subtle, fundamental blend properties. These results are invaluable in guiding the design and optimization of future devices in plastic electronics applications and provide an empirical basis for modeling and simulation of organic solar cells.

Homolytische aromatische Substitutionen werden für die effiziente regioselektive Synthese von Helicenen, Phenanthrenen und Azahelicenen genutzt. Der Einsatz von Halogen‐ und Alkoxysubstituenten, um den stereochemischen Verlauf der Reaktionen zu steuern, und röntgenographische Untersuchungen der erhaltenen Helicene wie des im Bild gezeigten (rot O) werden beschrieben.