Characterization of novel all-plastic electrochromic devices:: electro-optic and voltammetric response

The control of transmittance and its use in glazing have powered the research on electrochromic devices in the last decade. The search for new materials to be used in different applications is a goal today. We characterize new electrochromic devices following an all-plastic construction. Poly(ethylendioxy-tiophene) (PEDOT) is used between plastic substrates and sandwiched symmetrically with a poly(ethylene oxide)-based polymer electrolyte. This multilayer acts as an electrochromic device without the necessity for an ITO layer. Several devices are tested to determine their electro-optical characteristics using cyclic voltammetry and complex impedance spectroscopy techniques, among others. Additionally, a protocol of electrical and optical characterization is proposed. The devices switch between 0 and 3 V with no dependence on the electric field direction, due to their layer construction symmetry. Impedance and voltammetry measurements show a hysteretic behavior from which charge injection can be derived. Finally, transmittance changes above 14% are measured at a 600-nm wavelength, so that further research must be done in materials and sticking process to improve the contrast. Bleaching and coloring times of 20 to 30 s make these devices potential candidates for applications in domotics, environment control or vision, and color filters. (C) 2004 society of Photo-Optical Instrumentation.