Electrochemical and Spectroelectrochemical Study of Polyazulene/BBL-PEO Donor-Acceptor Composite Layers

Donor-acceptor composite layers made of the electrically conducting polymers p-type polyazulene (PAz) and n-type polybenzimidazobenzophenanthroline-poly(ethylene oxide) (BBL-PEO) were studied. The water dispersible BBL-PEO was solution-cast on PAz electropolymerized on Pt or ITO glass electrodes or on the bare electrode surfaces. The doping behavior within both the n- and p-doping potential regions was studied by cyclic voltammetry and in situ spectroelectrochemical techniques: UV-visible and FTIR-ATR spectroscopy. All of the results showed contributions from both polymers in the composites, besides the spectral behaviors in the n-doping potential region were mainly controlled by BBL-PEO and in the p-doping region by PAz. Rather stable donor-acceptor composites with the formation of charge carriers in both n- and p-doping regions were formed. In the BBL-PEO/PAz composite PAz was found to have a higher promoting effect on the formation of charge carriers than in the PAz/BBL-PEO composite. The composites stayed conducting within a broad negative potential region while some charges appeared to be trapped in the layers after the negative potential scan.