Conjugated Copolymers of Cyanosubstituted Pol(p-phenylene vinylene) with Phenylene Ethynylene and Thienylene Vinylene Moieties: Synthesis, Optical, and Electrochemical Properties

摘要

Three alternating conjugated copolymers of cyanosubstituted poly(p-phenylene vinylene) (CN-PPV) with phenylene ethynylene and thienylene vinylene moieties, P1, P2, and P3, were synthesized via cross-coupling polycondensation with Pd(PPh3)(2)Cl-2 as a catalyst. Their structures were confirmed by H-1-NMR, IR spectroscopy, elemental analysis, and gel permeation chromatography, and the thermal, photophysical, and electrochemical properties of the copolymers were also investigated. The incorporation of a triple bond into the CN-PPV backbone led to higher reduction potentials, which corresponded to lower lowest unoccupied molecular orbital energy levels. The three copolymers possessed broader absorption spectra, especially copolymer P3 with its polymerization units containing two thiophene rings, which showed the broadest absorption spectrum, from 300 to 710 nm. Their high electron affinities, broad absorptions, and relatively higher oxidation potentials make the copolymers potentially good electron-acceptor material for use in photovoltaic devices.