Whereas, EG/GOPS-PEDOT:PSS displayed solely Rb + uptake representing proton-cation exchange. In 95% sulfuric acid treated crys-PEDOT:PSS initial proton concentration is minimal as effectively all PSS sulfonates are dopants counterbalancing positive electronic charge on PEDOT, thus no significant proton-cation exchange occurs upon exposure. Instead, in the absence of Donnan exclusion charge balanced anions and cations diffuse into the film (Figure ). Further, excess anions accumulate as the equilibrium doping level in neutral aqueous environments is higher than in the sulfuric acid processing conditions, resulting in an ~30% excess of Br -with respect to Rb + . When electrochemically dedoped (-0.6 V vs Ag/AgCl), the electronic charge density on the PEDOT is decreased both through the removal of mobile Br -dopants, and the accumulation of excess Rb + cations that counterbalance fixed PSS-dopants, supplanting positive electronic charge (Figure ). The resulting dedoped composition has a ~37% excess Rb + with respect to Br -. Finally, when electrochemically redoped back to a high oxidation state (+0.6 V vs Ag/AgCl), the Br -concentration climbs and the Rb + concentration drops (Figure ). The resulting redoped composition has a ~55% excess Br -with respect to Rb + , with the excess Br - functioning as dopants, stabilizing positive electronic charge on PEDOT.