Electropolymerized Self‐Assembled Monolayers of a 3,4‐Ethylenedioxythiophene‐Thiophene Hybrid System

Abstract

Self‐assembled monolayers (SAMs) of a conjugated bithiophenic system connected to an alkanethiol chain have been deposited on gold surface. The electroactive bithiophenic system involves a 3,4‐ethylenedioxythiophene (EDOT) unit and a thiophene ring on which an alkanethiol is attached at the internal β‐position via a sulfide linkage. The analysis of the structure of the SAMs by IR spectroscopy, ellipsometry, contact angle measurement and X‐ray photoelectron spectroscopy (XPS) provides consistent results indicating compact monolayers in which the alkyl linkers are arranged in an almost vertical fashion while the bithiophenic‐conjugated systems are essentially parallel to the surface. Cyclic voltammetry shows that application of a few potential scans to SAMs immersed in a medium containing only a supporting electrolyte leads to the typical electropolymerization curves while the CV of the electrooxized monolayer exhibits a reversible cyclic voltammogram characteristic of a stable electroactive extended conjugated system. The characterization of the electropolymerized monolayers by IR spectroscopy, ellipsometry, contact angle measurement, and XPS indicates compact monolayers. The analysis of the current voltage characteristics of the monolayers by conducting AFM before and after electrooxidation shows that the enhancement of the effective conjugation resulting from electropolymerization leads to a significant increase of the transport properties.

Modular Functionalization of Electrodes by Cross‐Coupling Reactions at Their Surfaces

“…The broad peak observed in Figure 3B) at lower potential, centered at 0.1 V vs Ag/AgCl, was defined as the reduction peak of the polymer. As described recently by Roncali et al,62 alkanethiols substituted by EDOT derivatives immobilized on gold electrodes formed a 2D polymer without the presence of monomers in solution if the immobilized monomers are close enough to each other. Here, since the starting surface 5 is not a monolayer, we did not assume that a 2D polymer is formed, but islets of PEDOT could be formed on the surface after oxidation of the immobilized BiEDOT subunits.…”

Thiolate Chemistry: A Powerful and Versatile Synthetic Tool for Immobilization/Functionalization of Oligothiophenes on a Gold Surface

“…[23,[32][33][34] In particular, the double fixation of a p-conjugated system with a controlled horizontal orientation can be of both fundamental and technical interest. [34,35] Besides an improved stability related to multiple anchoring sites, [5f, 9a, 34] such horizontal orientation is considerably more efficient for absorption of incident light.…”

Electroactive Self‐Assembled Monolayers for Enhanced Efficiency and Stability of Electropolymerized Luminescent Films and Devices

“…One way to realize the chemical bonding of EP films onto electrodes is in virtue of the pre‐modified electrode with electroactive self‐assembled monolayers (SAMs), which provide terminal electropoly‐merizable groups for grafting subsequent EP films 9–11. Unfortunately, there are rarely reports on the utilization of this approach in EP luminescent diodes for improving device performance.…”