Electrochimica Acta, Vol.192, 52-60, 2016
Morphology and Doping Level of Electropolymerized Biselenophene-Flanked 3,4-Ethylenedioxythiophene Polymer: Effect of Solvents and Electrolytes
Biselenophene-flanked 3,4-ethylenedioxythiophene (EDOT) based polymer films were obtained by electrochemical polymerization. The effects of polymerization conditions such as supporting electrolytes and solvents on doping level, optical property and morphology of the polymer films were systematically studied. Interestingly, we found that polymer prepared by using different supporting electrolytes (TBAPF(6), TBABF(4) and TBACIO(4)) has significant effects on the doping level of the polymer films, whereas electropolymerized solvents (acetonitrile and dichloromethane) has no such effects on doping level. The polymer films show reversible dedoping and doping behavior upon treatment with hydrazine hydrate and iodine respectively. Biselenophene-flanked EDOT polymer shows a band gap of about 1.6 eV which is comparable to poly(3,4- ethylenedioxythiophene) (PEDOT) and parent polyselenophene, whereas finetuning of HOMO and LUMO energy levels has been found. In contrast, we observed that electropolymerized solvent has a major effect on morphology of the polymer films, while supporting electrolyte has very minor effects on the morphology. The surface morphologies of the polymer films were characterized by scanning electron microscope (SEM) and atomic force microscope (AFM) techniques. We also present an efficient synthesis of bisthiophene-flanked bridged EDOT (ETTE), and biselenophene-flanked bridged EDOT (ESeSeE), and their electrochemical polymerization, characterizations and throughout comparison where applicable. A density functional theory (DFT) calculation of the corresponding polymers and a comparison with polythiophene (PT), polyselenophene (PSe), PEDOT and EDOT- based copolymers (PETE and PESeE) has been made. (C) 2016 Elsevier Ltd. All rights reserved.
Keywords:Biselenophene-flanked EDOT;Electropolymerization;Morphology & Doping-dedoping;Optoelectronic properties;Computational