Relationship between enhancement of PEDOT:PSSconductivity by solvent treatment and PSSchain reorganization

The treatment of water‐soluble PEDOT:PSS copolymer film by DMSO or DMF considerably enhances its electrical conductivity. The mechanism leading to a new molecular conformation in the PEDOT:PSS layer was investigated by in situ ATR, PM‐IRRAS and XPS spectroscopies. The release of PSS chains containing excess [Na+, (−Φ‐SO3−)‐] and (−Φ‐SO3H)‐] moieties by the solvent treatment and the implications of this process are discussed. By comparison with a NaPSS/HPSS adduct, the essential role of the conformational reorganization of the poly(styrene sulfonic/sulfonate) chains via hydrogen bonds between SO3H functions is demonstrated. Residual water molecules play a fundamental role both in the removal of excess sulfonates or sulfonic groups, the separation of the (Na, H, PSS) chains, which can then be extracted, and the establishment of the suitable PEDOT conformation.