Synthesis and characterization of novel conjugated copolymers containing 3,4-dialkoxythiophene and 1,3,4-oxadiazole units

In this report we describe the synthesis, optical and electrochemical properties of new conjugated copolymers (P1-P4) based on 3,4-dialkoxythiophene and 1,3,4-oxadiazole units. The copolymers are prepared using the precursor polyhydrazide route. The chemical structures of the copolymers are confirmed using FTIR, NMR spectroscopy and CHNS analysis. The polymers exhibit good thermal stability with the onset decomposition temperature in nitrogen at around 300 °C. The optical and charge-transporting properties of the copolymers are investigated by UV-visible absorption spectroscopy, fluorescence emission spectroscopy and cyclic voltammetry. The polymers depicted blue/green fluorescence under the irradiation of UV light. Cyclic voltammetry studies reveal that these copolymers have low-lying LUMO energy levels ranging from −3.28 to −3.32 eV and high-lying HOMO energy levels ranging from −5.26 to −5.62 eV, which indicated that they may be promising candidates for the fabrication of polymer light-emitting diodes. In addition, the copolymers showed good third-order non-linear optical properties.