Rapid 2D growth of the PEDOT islands parallel to the L|L interface leads to a PEDOT thin film coating the full interface after ca. 25 cycles at 25 mV•s -1 as indicated by the complete disappearance of the sharp negative peak labelled β (Fig. ). IET then transitions from being purely electrochemically driven to involving simultaneous electrochemical and chemical processes. At this point, EDOT oligomers present in a high concentration in the organic EDL undergo chemical coupling. Likely, EDOT oligomers also chemically oxidise monomers in the diffusion zone of the organic EDL. Simultaneously, the electrochemically polarisable PEDOT thin film continues to oxidise both EDOT monomers and oligomers, as shown schematically in Fig. . While many processes can take place, the most dominant reaction is likely the oxidation of EDOT oligomers by the PEDOT thin film. From the 35 th cycle onwards, the CVs stabilise and only increase very moderately with further cycling (Fig. ). This may be due to the PEDOT thin film reaching a certain thickness (above 20 nm for example) in excess of that of the ITIES. In this scenario, the entirety of the PEDOT thin film coated L|L interface reaches a similar potential distribution, with the rate of polymerisation being controlled by either mass transport (e.g., the diffusion of SO4 2-counteranions through the film to maintain electroneutrality locally) or the rate of IET. At this stage, it is likely that the PEDOT thin film limits the movement and quantity of ions that charge the interface, like a membrane.