Electrocoupling process and electrochemical deposition of poly(9-vinylcarbazole-co-4-vinyltriphenylamine) films

Poly(9-vinylcarbazole-co-4-vinyltriphenylamine)s, PVKT21 and PVKT45 with 21 mol% and 45 mol% pendant triphenylamine groups respectively, were electrochemically deposited as crosslinked thin films through electrocoupling of pendant triphenylamine moieties during the oxidation process. The electrocoupling process has been elucidated by electrochemical and spectroelectrochemical investigations which reveal that mainly triphenylamine undergoes electrocoupling. The color of the electrodeposited film changes from colorless (neutral state) to orange (semi-oxidized state) and finally to bluish-green (fully oxidized state) when the applied potential is increased from 0 V to 2 V. Electrodeposited films were characterized by atomic force microscope (AFM) and the results show that their morphology can be controlled by changing the precursor concentrations. Through this method a smooth thin film can be fabricated for the application in electroluminescent devices. The electroluminescent devices using electrodeposited PVKTs as hole-transporting layer effectively enhance device performance.