Preparation of conductive PDDA/(PEDOT:PSS) multilayer thin film: Influence of polyelectrolyte solution composition
Résumé
Self-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 to
control its thickness, the effects of pH, type of electrolyte, ionic strength and polyelectrolyte concentration
were investigated. Optical reflectometry measurements show that the pH of the solutions has no
effect on the film growth while the adsorbed amount increases more rapidly when BaCl2 is used instead
of NaCl as electrolyte. An increase in the ionic strength (with NaCl) induces a change in the growth regime
from a linear to an exponential one at low polyelectrolyte concentration. As UV–vis measurements
indicate, no decomplexation of PEDOT was recorded after film preparation. With polyelectrolyte concentration
below 1 g L1, no conductive films were obtained even if 50 bilayers were deposited. A conductive
film was prepared with a polyelectrolyte concentration of 1 g L1 and the measured conductivity was
0.3 S m1. A slight increase in conductivity was recorded when BaCl2 was used probably due to a
modification of the film structure.