Design, synthesis and characterization have been carried out on poly(thiophene)s bearing electron-deficient side chains. The influence of structure on the optical characteristics was studied in detail using molecular orbital calculations. The model compounds have been synthesized and their photoabsorption, photo- and electro-emission characteristics were studied. The results indicate that substituting appropriate heteroaromatic groups to the thiophene chain can enhance electro-emission, even with a single emissive layer, in PLEDs. © The Royal Society of Chemistry 2006.