Synthesis and characterization of new light-emitting copolymers containing 3,4-dialkoxythiophenes

Abstract

We report the synthesis, optical and electrochemical properties of a new series of polyoxadiazoles (P1-P3) consisting of 3,4-dialkoxythiophene and 1,4-divinylbenzene units. The polymers are prepared using the precursor polyhydrazide route. The polymers have well defined structure and exhibit good thermal stability with the onset decomposition temperature in nitrogen at around 330 C. The optical and charge-transporting properties of the polymers are investigated by UV-vis spectroscopy, fluorescence emission spectroscopy and cyclic voltammetry. The UV-vis absorption spectra of polymers in solution showed a maximum at around 380 nm. The polymers depicted bluish-green fluorescence in solutions and green fluorescence in thin films. Cyclic voltammetry studies reveal that these copolymers have low-lying LUMO energy levels ranging from 3.25 to 3.31 eV and HOMO energy levels ranging from 5.48 to 5.56 eV, which indicated that the polymers are expected to provide enhanced charge-transporting (electron transport/hole blocking) properties for the development of efficient polymer light-emitting diodes (PLEDs). 2006 Elsevier B.V. All rights reserved.