Donor-Mediated Band Gap Reduction in a Homologous Series of Conjugated Polymers

A family of six donor−acceptor−donor monomers was synthesized using combinations of
thiophene, 3,4-ethylenedioxythiophene and 3,4-ethylenedioxypyrrole as donor moieties, and cyanovinylene
as the acceptor moiety, to understand the effects of modified donor ability on the optoelectronic and redox
properties of the resulting electropolymerized materials. Spectroelectrochemistry, differential pulse voltammetry, and cyclic voltammetry results indicate band gaps ranging from 1.1 to 1.6 eV and suggest that
these polymers can be both p-type and n-type doped at accessible potentials. In situ conductivity results
indicate that the n-type conductivity magnitude is modest, and the conductivity profile indicates a redox
conductivity mechanism as opposed to a delocalized electronic band mechanism as observed for p-type
doping.