Combination of donor characters in a donor-acceptor-donor (DAD) type polymer containing benzothiadiazole as the acceptor unit

benzothiadiazole bearing donor-acceptor-donor (D-A-D) type monomer (M-3) was synthesized using the combination of 3, 4-ethylenedioxythiophene (EDOT) and thiophene donor units to understand the effect of donor strength on the optoelectronic and electrochemical properties. The resulting monomer was polymerized electrochemically (P-3) and compared with its symmetrical thiophene (P-1) and EDOT (P-2) bearing homologues whether there exists a combination of the electrochemical and optical characteristics. Also, copolymer studies were performed with symmetrical thiophene (M-1) and EDOT (M-2) containing monomers in order to compare the results with P-3. Cyclic voltammetry (CV) and spectro-electrochemistry results revealed that P-3 is a low band gap polymer (1.18 eV) having both p-and n-type property which is superior to the copolymers synthesized using M-1 and M-2. (C) 2010 Elsevier B. V. All rights reserved.