Metal-like Charge Transport in PEDOT(OH) Films by Post-processing Side Chain Removal from a Soluble Precursor Polymer

Herein, a route to produce highly electrically conductive doped hydroxymethyl functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) films, termed PEDOT(OH) with metal-like charge transport properties using a fully solution processable precursor polymer is reported. This is achieved via an ester-functionalized PEDOT derivative [PEDOT(EHE)] that is soluble in a range of solvents with excellent film-forming ability. PEDOT(EHE) demonstrates moderate electrical conductivities of 20-60 S cm^-1 and hopping-like (i.e., thermally activated) transport when doped with ferric tosylate (FeTos₃ ). Upon basic hydrolysis of PEDOT(EHE) films, the electrically insulative side chains are cleaved and washed from the polymer film, leaving a densified film of PEDOT(OH). These films, when optimally doped, reach electrical conductivities of ≈1200 S cm^-1 and demonstrate metal-like (i.e., thermally deactivated and band-like) transport properties and high stability at comparable doping levels.