Preparation of conductive PDDA/(PEDOT:PSS) multilayer thin film: Influence of polyelectrolyte solution composition

International audienceSelf-assembled multilayer films made of PEDOT:PSS poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)and PDDA poly(diallyldimethylammonium chloride) were prepared using layer-by-layer method.In order to modify the growth regime of the multilayer, to fabricate an electrical conductive film and tocontrol its thickness, the effects of pH, type of electrolyte, ionic strength and polyelectrolyte concentrationwere investigated. Optical reflectometry measurements show that the pH of the solutions has noeffect on the film growth while the adsorbed amount increases more rapidly when BaCl2 is used insteadof NaCl as electrolyte. An increase in the ionic strength (with NaCl) induces a change in the growth regimefrom a linear to an exponential one at low polyelectrolyte concentration. As UV–vis measurementsindicate, no decomplexation of PEDOT was recorded after film preparation. With polyelectrolyte concentrationbelow 1 g L1, no conductive films were obtained even if 50 bilayers were deposited. A conductivefilm was prepared with a polyelectrolyte concentration of 1 g L1 and the measured conductivity was0.3 S m1. A slight increase in conductivity was recorded when BaCl2 was used probably due to amodification of the film structure