Solid-state electrochromic devices via Ionic Self-Assembled Multilayers (ISAM) of a polyviologen

A PV was synthesized by polymerization of N,N′-bis(δ- aminopropyl)-4,4′-bipyridinium bromide hydrobromide (APD) and isophthaloyl chloride (ISP). The PV was completely soluble in water as well as in organic solvents. The spectroelectrochemical and EC properties of the resulting ionic self-assembled multilayers of PV/poly-(2-acrylamido-2-methylpropanesulfonic acid) (PAMPs) were examined by cyclic voltammetry, FT-IR spectroscopy, UV-vis spectroscopy, optical switching and current density measurements. Solid state devices made of PV films sandwiched with PANI as a counter electrode have switching times of 100-250 ms. 40 Bilayer films of PV/PAMPs show high contrast (ΔT = 61%) in 0.1 M NaClO₄ liquid electrolyte solution and CE as high as 57 cm² C \one of the highest reported so far for any bipyridinium salt system.