Hybrid PEDOT-Metal Nanoparticles - New Substitutes for PEDOT:PSS in Electrochromic Layers - Towards Improved Performance

Hybrid organicinorganic nanocomposites of poly(3,4-ethylenedioxythiophene) (PEDOT) and silver or gold {PEDOTmetal (PEDOTM) nano-objects (M = Ag, Au) (particle diameter down to 60 nm)} were prepared by a one-pot oxidative aqueous dispersion polymerization using ammonium persulfate as an oxidant and the corresponding metal salts as co-oxidant (HAuCl4 and AgNO3) in the presence of pyrrole-modified-poly(N-vinylpyrrolidone-co-vinyl alcohol) (PVP-co-PVAL-mod-Py) stabilizer. The hydrophilic character of such a stabilizer enhances the polymer layer through hydrophilic interactions, which leads to a smooth surface with high wetting properties for subsequent electropolymerizations. PEDOTM is more conducting than the commercially available PEDOT:PSS, in which the PSS acts as an insulating agent (electrical conductivities up to 1.25 Scm(-1)). These nanocomposites were used to replace PEDOT:PSS as anchoring layer for further EDOT monomer polymerization, providing an improvement of the electrochromic properties of PEDOT in terms of not only contrast ratio and coloration efficiency but also switching time response.