We report on the electro-optic and dielectric properties of optical switching devices based on poly(3,4-ethylene dioxythiophene):polystyrene sulfonate (PEDOT:PSS) electrodes sandwiching a polymer-dispersed liquid crystal (PDLC) layer. We demonstrate that the frequency dependence of the driving electric field on the optical properties of these devices allows the fabrication of flexible bandpass light modulators. The (PEDOT:PSS) electrodes are characterized using UV-Vis, scanning electron microscopy, Raman, conductive atomic force microscopy, and linear four probe technique. The PEDOT:PSS/PDLC-based displays exhibit similar electro-optical performances to those of ITO-based devices. In addition, it can function as a bandpass light modulator. This behavior resulted from depolarization fields (Maxwell–Wagner–Sillars effects) occurring (i) at the polymer/LC interface (low frequency) and (ii) between nanometer-sized conductive PEDOT-rich domains and poorly conductive PSS-rich areas present in the bulk and at the surface of the electrode (high frequency).

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Relaxation mechanisms in polyaniline (PANI)/Reduced Graphene Oxide (RGO) nanocomposites are investigated using broad band dielectric spectroscopy. The multilayered nanostructural features of the composites and the intimate interactions between PANI and RGO are evidenced by field emission scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. Increasing the RGO fraction in the composites results in a relaxation process observed at a frequency of ca. 5 kHz. This mechanism is associated with an electrical charge trapping phenomenon occurring at the PANI/RGO interfaces. The dielectric relaxation processes are interpreted according to the Sillars approach and the results are consistent with the presence of conducting prolate spheroids (RGO) embedded into a polymeric matrix (PANI). Dielectric permittivity data are analyzed within the framework of the Kohlrausch-William-Watts model, evidencing a Debye-like relaxation process.

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