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Abstract: SnO2 nanoparticle layers were synthesized as electrodes, assembled in lithium half-cells and tested by combining cyclic voltammetry and long-term cycling behavior, supplemented by XPS- and SEM-investigations. The cycling behavior of SnO2 shows characteristic features: large difference between discharging and charging capacity for the first cycles, pronounced negative slope, corresponding to huge degradation of specific capacity and a shallower slope after achieving coulombic efficiency around 100%. The areas under the charge and discharge curves of the voltammograms are assumed to be a measure for the amount of oxidation and reduction, respectively. The integrated reduction and oxidation areas are not equal after the first cycle (58:42). The whole reaction of the cycle can be described as partially reversible. Consequently, residuals remain, not contributing to capacity in the next cycle. However, after achieving coulombic efficiency around 100%, the area ratio becomes 50:50. The goal of XPS investigation is to show the evolution of the phases while crossing specific potentials. It was shown that the SEI is appearing for the first time by crossing the potential of 1 V. This SEI is dominated by lithium carbonate but also consists of a complex mixture of different lithium compounds and other decomposition products of the electrolyte. [Copyright &y& Elsevier]

For inorganic semiconductors crystalline order leads to a band structure which gives rise to drastic differences to the disordered material. An example is the presence of an indirect band gap. For organic semiconductors such effects are typically not considered, since the bands are normally flat, and the band-gap therefore is direct. Herein we show results from electronic structure calculations demonstrating that ordered arrays of porphyrins reveal a small dispersion of occupied and unoccupied bands leading to the formation of a small indirect band gap. We demonstrate herein that such ordered structures can be fabricated by liquid-phase epitaxy and that the corresponding crystalline organic semiconductors exhibit superior photophysical properties, including large charge-carrier mobility and an unusually large charge-carrier generation efficiency. We have fabricated a prototype organic photovoltaic device based on this novel material exhibiting a remarkable efficiency., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)