1 results for Abboud, K.A.

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

    Thomas, C.A.; Zong, K.; Abboud, K.A.; Steel, P.J.; Reynolds, J.R. (2004)

    Journal Articles
    University of Canterbury Library

    A family of six Donor-Acceptor-Donor (D-A-D) monomers was synthesized using combinations of thiophene, 3,4-ethylenedioxythiophene (EDOT) and 3,4-ethylenedioxypyrrole (EDOP) as donor moieties, and cyanovinylene as the acceptor moiety, in order to understand the effects of modified donor ability on the optoelectronic and redox properties of the resulting electropolymerized materials. Spectroelectrochemistry indicated band gaps (Eg) ranging from 1.1 eV to 1.6 eV as donor quality increased and these values were confirmed by differential pulse voltammetry (DPV) and cyclic voltammetry (CV). CV results 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. As suggested by the low band gaps and confirmed by colorimetry, these polymers are cathodically coloring and undergo color transitions from a deep absorbing blue (neutral) to a nearly transparent light blue (p-type form), yet do not undergo color changes upon reduction in TBA+, TEA+ or Li+ containing electrolytes. These results combine to suggest that the donor controls the HOMO/valence band level in the polymer and the strongest donor necessary to minimize band gap and maximize conductivity of the reduced state is EDOT as increasing the donor character (using EDOP) did not reduce the band gap further.

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