Study on the Solvent Effect in the Coating of Conductive Polythiophene Derivative

The surface resistance of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT/PSS), which has appeared to be one of the most successful conductive polymers, is affected by the solvent. In this paper, pellet-type PEDOT/PSS was suspended in , ethanol (EtOH), ethylene glycol (EG) or dimethylsulfoxide (DMSO), and coated on PET film. The surface resistances of the films made from EG or DMSO suspension were observed to be lower, nearly by 2 orders of magnitude, than that made from suspension. No significant difference among four kinds of films was observed when the thermal properties and chemical structures were investigated by TGA and XPS, respectively. However, particle size of PEDOT/PSS was in the range of in EG or DMSO, on the other hand, less than in . It is considered that the particle size of PEDOT/PSS in the suspension plays an important role for the surface resistance.