The thermal behaviour of an organic photovoltaic (OPV) binary system comprised of a liquidcrystalline fluorene-based polymer and a fullerene derivative is investigated. We employ variabletemperature ellipsometry complemented by photo-and electroluminescence spectroscopy as well as optical microscopy and scanning force nanoscopy to explore phase transitions of blend thin films. The high glass transition temperature correlates with the good thermal stability of solar cells based on these materials. Furthermore, we observe partial miscibility of the donor and acceptor together with the tendency of excess fullerene derivative to segregate into exceedingly large domains. Thus, for charge generation less adequate bulk-heterojunction nanostructures are poised to develop if this mixture is exposed to more elevated temperatures. Gratifyingly, the solubility of the fullerene derivative in the polymer phase is found to decrease if a higher molecular-weight polymer fraction is employed, which offers routes towards improving the photovoltaic performance of non-crystalline OPV blends.

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The effect of peak power in a high power impulse magnetron sputtering (HiPIMS) reactive deposition of TiO 2 films has been studied with respect to the deposition rate and coating properties. With increasing peak power not only the ionization of the sputtered material increases but also their energy. In order to correlate the variation in the ion energy distributions with the film properties, the phase composition, density and optical properties of the films grown with different HiPIMS-parmeters have been investigated and compared to a film grown using direct current magnetron sputtering (DCMS). All experiments were performed for constant average power and pulse on time (100W and 35 μs, respectively), different peak powers were achieved by varying the frequency of pulsing. Ion energy distributions for Ti and O and its dependence on the process conditions have been studied. It was found that films with the highest density and highest refractive index were grown under moderate HiPIMS conditions (moderate peak powers) resulting in only a small loss in massdeposition rate compared to DCMS. It was further found that TiO 2 films with anatase and rutile phases can be grown at room temperature without substrate heating and without postdeposition annealing.

Chirality, tailored by external morphology and internal composition, has been realized by controlled curved-lattice epitaxial growth of In(x)Al(1-x)N nanospirals. The curved morphology of the spiral segments is a result of a lateral compositional gradient while maintaining a preferred crystallographic growth direction, implying a lateral gradient in optical properties. Individual nanospirals show an asymmetric core-shell structure with curved basal planes. Mueller matrix spectroscopic ellipsometry shows that the tailored chirality is manifested in the polarization state of light reflected off the nanospirals.

There is an increasing demand for glass materials with better mechanical and optical properties for display and electronic applications. This paper describes the deposition of novel thin films of Mg-Si-ON onto float glass substrates. Amorphous thin films in the Mg-Si-ON system with high nitrogen and magnesium contents were deposited by reactive RF magnetron co-sputtering from Mg and Si targets in Ar/N 2 /O 2 gas mixtures. The thin films studied span an unprecedented range of compositions up to 45 at% Mg and 80 at% N out of cations and anions respectively. Thin films in the Mg-Si-ON system were found to be homogeneous and transparent in the visible region. Mechanical properties like hardness (H) and reduced elastic modulus (Eᵣ) show high values, up to 21 GPa and 166 GPa respectively. The refractive index (1.87-2.00) increases with increasing magnesium and nitrogen contents.