Synthesis, characterizations and properties of new copoly(aryl ether)s with alternate hole- and electron-transporting fluorophores

Three novel copoly(aryl ether)s, consisting of alternate isolated hole-transporting (2,5-dihexyloxy-1,4-distyrylbenzene) and electron-transporting (p-quaterphenyl or aromatic 1,3,4-oxadiazole) segments, were synthesized from corresponding bis(phenol) and bis(fluoride) monomers by nucleophilic displacement reaction. These copolymers are soluble in common organic solvents and exhibit good thermal stability with 5% weight loss temperature above 400 °C in nitrogen atmosphere. The photoluminescent (PL) spectra and quantum yields of these copolymers are dependent on the composition of the isolated fluorophores. The HOMO and LUMO energy levels of these copolymers have been estimated from their cyclic voltammograms. All the observations directly proved that the oxidation in copolymers starts at the hole transporting segments. Moreover, the electron and hole affinities can be enhanced simultaneously by introducing isolated hole-transporting and electron-transporting segments, in which p-quaterphenyl is more electron-affinitive than aromatic 1,3,4-oxadiazole chromophores.