Electro-optic and dielectric properties of optical switching devices based on liquid crystal dispersions and driven by conducting polymer [poly(3,4-ethylene dioxythiophene):polystyrene sulfonate (PEDOT:PSS)]-coated electrodes

Abstract

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).