Surface Grafting of Conjugated Polymers onto Self-assembled Monolayer Modified Conducting Substrates by Electrochemistry

A new method of grafting conjugated polymers onto solid substrates by self-assembled monolayers (SAM) and electrochemistry is described. The polyfluorene was designed to have the carbazole group as the pendant group to offer electropolymerizability. As has been studied, carbazole is easily electropolymerized by cyclic voltammetry at low oxidation potential. In our study, this copolymer was deposited and cross-linked on the carbazole-SAM modified ITO substrate through electrochemistry. Consistent with the oxidation potential differences between polyfluorene and the carbazole unit, electropolymerization of the pendant carbazole groups has no effect on the polymer backbone. The carbazole group was chosen because of its better band gap match between the anode and the polyfluorene and at the same time it gives better adhesion contact between ITO and the polymer layer. In addition, the electrochemically deposited polymer becomes cross-linked, rendering it insoluble in any solvent.