Effect of chalcogen substitution on aqueous dispersions of poly(3,4-ethylenedioxythiophene)s:poly(4-styrenesulfonate) and their flexible conducting films

Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) is a hotspot among current researched conducting polymers and its conductivity could be significantly enhanced by post-treatment with dimethyl sulphoxide (DMSO). In this work, five S and Se analogues of 3,4-ethylenedioxythiophene (EDOT) were synthesized, and chemically oxidative polymerized (COP) to obtain corresponding free-standing films of Poly(3,4-ethylenedioxythiophene)s:poly(4-styrenesulfonate) (PEDOTs:PSS). The effect of chalcogen substitution on the physicochemical properties and conductive performances of PEDOT:PSS film have been demonstrated. In contrast to the conductivities about 10⁻²–10⁻¹ S cm⁻¹ for PEDOT:PSS and poly(3,4-ethylenedioxyselenophene):poly(4-styrenesulfonate) (PEDOS:PSS), other PEDOTs:PSS films had the conductivities about 10⁻⁴–10⁻⁵ S cm⁻¹. The conductive enhancement effect of DMSO second-doping is suitable for PEDOTs:PSS films except the all-sulfur analogs of PEDOT:PSS (PEDTT:PSS and PEDTS:PSS), and the critical role of the presence of the O atoms in the ethylene bridges and the S atom in the thiophene ring has been illustrated. This work may help understand the structure-performance relationship of PEDOT family and the further development of PEDOTs in areas where the PEDOT seems monotonous and the high conductivity is not necessary, such as antistatic coating, anticorrosive coating, multi-colored electrochromics and so on.