Polymer Blends and Composites

Abstract

The implementation of flexible Organic Electronic (OE) devices in a large variety of consumer applications (generation of electricity, visualization of information, lighting, sensing, etc.) will significantly improve our everyday life. The typical OE device (e.g. a organic photovoltaic cell—OPV) consists of multilayered structures (30–200 nm thick each) fabricated onto rigid (e.g. glass) and/or flexible substrates (as PET, PEN) from transparent and electrically active organic nanolayers. The OE device core is the active or the organic semiconducting (polymer or small molecules) layer, that absorbs photons and generates electric charges, sandwiched between the device electrodes. Finally, the device is encapsulated by barrier layers for the protection of the photoactive layers against degradation and corrosion due to atmospheric gas penetration inside the device. The understanding of the correlation between the polymer blend structure and its optical and electrical properties, and the achievement of the desirable morphology at nanometer scale, is a prerequisite in order to optimize the device performance and stability. Spectroscopic Ellipsometry (SE) from the infrared to the visible and far ultraviolet spectral region has been widely used to provide significant insights on the optical properties, blend morphology, and composition of the polymer blends that are used as active layers in OE devices. In this chapter, we summarize on the latest advances in the implementation of SE from the infrared to the visible and ultraviolet spectral region, for the investigation of the optical and electronic properties, composition profile and structure of polymer nanomaterials that are used as organic semiconductors and transparent electrodes for OE devices, and we discuss the effect of their nanoscale structure on their properties and functionality.