Scheme 3. Proposed structure of PEDOT:PSS at the EDOT : PSS weight ratio of 1 : 11 and at various EDOT : Na₂S₂O₈ mole ratios: at an EDOT : Na₂S₂O₈ mole ratio (a) lower than 1 : 2, (b) 1 : 2, where SO₄²⁻ acts as a secondary dopant and (c) higher than 1 : 2, where a higher PSSNa amount is generated.