Conductive ink based on PEDOT nanoparticles dispersed in water without organic solvents, passivant agents or metallic residues

Abstract Poly(3,4-ethyledioxythiophene), or PEDOT, is a well-known polymer used in organic electronics due to its high electrical conductivity, flexibility and optical transparency. This study proposes a simple and fast method to obtain a conductive ink based on PEDOT aqueous dispersion, stable for months without surfactants, polymers, or additives, formed by polymer nanoparticles with low metallic content. PEDOT was obtained by oxidative polymerization of the monomer with anhydrous iron(III) chloride in acetonitrile. The obtained solid was washed and the residue content is decreased to lower than 0.5%. Fresh polymerized and wet PEDOT was sonicated in water and resulted in aqueous ink with concentration up to 1.145 g L−1, stabilized by electrostatic repulsion. This conductive ink was deposited via air-brush technique on glass substrates and has formed conductive and transparent thin films with sheet resistances of 1 and 20 kΩ sq−1 and transmittances at 550 nm of 50% and 80% respectively. Those electrodes have PEDOT distributed over macroscopic distances and recovering the entire substrates, which shows the great potential of the aqueous PEDOT ink as well as the deposition technique to be used in organic electronic devices.