Bottom-Up Electrochemical Fabrication of Conjugated Ultrathin Layers with Tailored switchable properties

Abstract

In this work, we develop a Bottom-Up Electrochemical Fabrication process of Conjugated Ultrathin Layers with Tailored switchable properties. To do so, we use ultrathin layers of covalently grafted oligo(bisthienylbenzene) (oligo(BTB)) as a switchable organic electrodes and perform 3,4-ethylenedioxythiophene (EDOT) oxidation on such organic layer. Adding only 3 nm of EDOT moieties (5 to 6 units) completely changes the switching properties of the layer without changing the surface concentration of the grafted electroactive species. As a consequence, a range of new materials, with tunable interfacial properties, is created through this bottom-up electrochemical process. They consist of oligo(BTB)-oligo(EDOT) di-block oligomers of various relative length grafted covalently on the underlying electrode. As an important result these ultrathin films retain reversible redox on/off switching and their switching potential can be finely tuned between 0.6 and -0.3 V/SCE despite an overall thickness that remains below 11 nm.