Effects of various imidazole-based weak bases and surfactant on the conductivity and transparency of poly(3,4-ethylenedioxythiophene) films

Poly(3,4-ethylenedioxythiophene) (PEDOT)-based conductive thin films with improved transparency and surface resistance can be prepared by using adequate weak bases and non-ionic surfactants. Among the imidazole-based weak bases, 2-ethyl-4-methyl-substituted imidazole showed the best performance in terms of surface resistance and transparency. It is speculated that 2-ethyl-4-methyl-imidazole causes reduced particle size because polymerization kinetics are retarded by the electron donating effect of ethyl and/or methyl groups in the imidazole ring. Addition of Triton X-100 may stabilize nanoscopic PEDOT particles in the coating solution resulting in low surface resistance (172 Ω/□) and enhanced transparency (>90%) of the PEDOT film.