Poly(3,4-ethyledioxythiophene), PEDOT, is a well-known polymer used in organic electronics due to its high electrical conductivity, flexibility and optical transparency. This study reveals a simple and fast method to obtain a conductive ink based on PEDOT aqueous dispersion. The ink remains stable for months without surfactants, polymers or additives and it is formed by polymer nanoparticles with low metallic content residue from the synthesis. PEDOT was obtained by oxidative polymerization of the monomer with anhydrous iron (III) chloride in acetonitrile. The obtained solid was washed in two steps, being the first with acetonitrile followed by water, and the residues 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, which is high for lyophobic dispersions. This conductive ink was deposited on glass substrates via air-brush technique, resulting in transparent and conductive thin films with sheet resistances of 1 and 20 kΩ/sq and optical transmittances at 550 nm of 50 and 80 % respectively. Those samples have PEDOT distributed over macroscopic distances and covering the entire substrates, which shows the great potential of the aqueous PEDOT ink to be used as electrode in organic electronic devices.
Reference:
[1] Matheus F.F. das Neves, João P. V. Damasceno, Osvaldo D.L. Junior, Aldo J.G. Zarbin, Lucimara S. Roman, Conductive ink based on PEDOT nanoparticles dispersed in water without organic solvents, passivant agents or metallic residues, Synth. Met., Vol. 272, 116657, 2021.