RESUMO
The ventral face of the wings of the butterfly Dione vanillae is covered with bright and shiny silvery spots. These areas contain densely packed ground- and coverscales with a bright metallic appearance reflecting more than 50% of light uniformly over the visible range. Our analysis shows that this optically attractive feature is caused by the inner microstructure of the scales located in these areas. Electron microscopy of cross sections through the scales shows that upper and lower lamina, supporting trabeculae, and topping ridges can be approximated by a 'circus tent'-like geometry. By simulating its optical properties, we show that a moderate disorder of this geometry is important for the uniform reflection of light resulting in the silvery appearance.
RESUMO
Gravure printing of functional thin-film layers of side-chain-substituted poly( para-phenyleneethynylene)s (PPEs) is reported. Rheological properties of PPEs in combination with the Hansen solubility model allowed the formulation of enhanced single-component inks. Layer evaluation is performed with reflectometric thin-film recordings in an optical setup for laterally resolved large-area investigation using imaging color reflectometry. An organic light-emitting diode in a simple glass/indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/PPE/LiF-Al stack was gravure-printed from the improved ink showing excellent luminance (542 cd m-2, U = 11.5 V) for this polymer class.
