Effects of solvent on carrier transport in poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate)

The aqueous solution of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) containing various organic solvents was coated on a poly(ethyleneterephthalate) film as a substrate and carrier transport properties were investigated. It was found that an addition of ethylene glycol lowered the sheet resistance by two or three orders of magnitude. The temperature dependence of conductivity of various PEDOT/PSS coatings was described one-dimensional variable range hopping where ethylene glycol was crucial to reduce the effective energy barrier for hopping of charge carriers between localized states.