Characterization of complicated electropolymerization using UV-vis spectroelectrochemistry and an electrochemical quartz-crystal microbalance with dissipation: A case study of tricarbazole derivatives

Electropolymerization is an effective way to produce conducting polymers. However, most complex electropolymerization mechanisms have not been elucidated due to the limitations of measurement techniques. Factors such as reaction potentials, intermediate structures and polymerization positions can have a strong influence on the mechanism, especially for complicated multi-electron processes. In this research, three tricarbazoles are chosen as examples to investigate the effects of substituents on their electropolymerization. Ionic species and mass changes are tracked using in situ UV-vis spectroelectrochemistry and an electrochemical quartz-crystal microbalance with dissipation. The results reveal a multi-step electron transfer process with different mechanisms, in which H-3Cz preferentially forms long-chain polymers and can be more easily doped/dedoped at inner carbazole positions than P-3Cz and E-3Cz, due to the higher activity of the radical cation and smaller steric hindrance.