Electrochemical behavior of electropolymerized and chemically synthesized hyperbranched polythiophenes.

Hyperbranched polythiophenes were synthesized by potentiodynamic electropolymerization of 2,2';3',2''-terthiophene and 5'-(2-thienyl)-2,2';3',2''-terthiophene. The molecular architecture, i.e., the extent of branching of the resulting polymers, could be adjusted by varying the switching potentials. We compare these systems to hyperbranched polythiophenes which we obtained via a simple one-pot synthesis route based on FeCl(3) oxidative polymerization of the monomers. Interestingly, we find that the properties of the electropolymerized materials obtained with high switching potentials are comparable to those of the chemically synthesized polythiophenes. A detailed optical and electrochemical characterization of these systems is performed showing the high potential of this material class for optoelectronic applications. Cyclic voltammetry coupled with in situ conductance measurements further reveal reversible doping upon oxidation (p-doping) and reduction (n-doping) and comparable values for the conductance for the chemically and electrochemically synthesized materials.