The solution processable alternating benzofuran/terfluorene copolymer bearing side oxadiazole groups (PBF-OXD) was synthesized and its optoelectronic properties and color stability were investigated. Electron-deficient and stereohindered oxadiazole units were used as pendent groups to compensate for the poor electron-transporting ability of a p-type polymer backbone, to depress the intermolecular pi-stacking, and to improve solubility while retaining polymer blue emission. PBF-OXD showed a glass transition at 135 degrees C and an onset decomposition temperature of similar to 345 degrees C. A simple EL device, with the configuration of ITO/PEDOT:PSS/PBF-OXD/Ba/Al, displayed a stable blue emission (lambda(max) = 434 nm), good color purity (full width half-maximum = 59 nm), maximum brightness of 1400 cd/m(2), and a maximum luminance efficiency of 0.95 cd/A. The PL and EL spectra changed slightly on annealing and on increasing the applied voltage. These results show that the as-synthesized copolymer PBF-OXD had integrated respective functions of its different building blocks and exhibited good thermal and color stability with improved EL performance. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5488-5497, 2009