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.

Transmission Mueller-matrix spectroscopic ellipsometry is applied to the cuticle of the beetle Cetonia aurata in the spectral range 300-1000 nm. The cuticle is optically reciprocal and exhibits circular Bragg filter features for green light. By using differential decomposition of the Mueller matrix, the circular and linear birefringence as well as dichroism of the beetle cuticle are quantified. A maximum value of structural optical activity of 560 degrees/mm is found. (C) 2016 Optical Society of America

Funding Agencies|Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University; Carl Tryggers Foundation [CTS:31]; Knut and Alice Wallenberg Foundation [2004.0233]; Consejo Nacional de Ciencia y Tecnologia (CONACYT); Vetenskapsradet (VR) [621-2011-4283]

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Ca-Si-ON thin films were deposited on commercial soda-lime silicate float glass, silica wafers and sapphire substrates by RF magnetron co-sputtering from Ca and Si targets in an Ar/N 2 /O 2 gas mixture. Chemical composition, surface morphology, hardness, reduced elastic modulus and optical properties of the films were investigated using X-ray photoelectron spectroscopy, scanning electron microscopy, nanoindentation, and spectroscopic ellipsometry. It was found that the composition of the films can be controlled by the Ca target power, predominantly, and by the reactive gas flow. Thin films in the Ca-Si-ON system are composed of N and Ca contents up to 31 eq. % and 60 eq. %, respectively. The films thickness ranges from 600 to 3000 nm and increases with increasing Ca target power. The films surface roughness varied between 2 and 12 nm, and approximately decreases with increasing power of Ca target. The hardness (4-12 GPa) and reduced elastic modulus (65-145 GPa) of the films increase and decrease with the N and Ca contents respectively. The refractive index (1.56-1.82) is primarily dictated by the N content. The properties are compared with findings for bulk glasses in the Ca-Si-(Al)-ON systems, and it is concluded that Ca-Si-ON thin films have higher values of hardness, elastic modulus and refractive index than bulk glasses of similar composition.