The asymmetric nature of the PEDOT thin film leads to each side having distinct physical properties. For example, sessile drop measurements highlight significant differences in hydrophobicity, with water droplet contact angles of 89.5 o and 112.6 o measured on the flat and rough sides, respectively (Fig. ). Atomic force microscopy (AFM) images of the topography of a PEDOT thin film folded back on itself clearly highlight the differences in surface roughness of either side (Fig. ) and revealed that the thickness of a thin film prepared by 50 DPSCA cycles is ca. 60 nm (Fig. (ii)-(iii)). (Supplementary Fig. ). Initially, after 50 DPSCA cycles, the thin film shows 2D growth parallel to the ITIES, a highly compact structure that is flat on both sides, and a thickness of 40 -60 nm (Fig. ). With continued interfacial electrosynthesis (up to 150 DPSCA cycles), secondary 3D growth begins to extend into the organic phase as the thickness of the PEDOT thin film increases (Fig. (ii)). This controllable secondary growth process leads to the formation of a very porous 3D structure with a thickness of up to ~ 850 nm after prolonged (> 300 DPSCA cycles) interfacial electrosynthesis (Fig. (iii)).