Five homologous series of α- and α,ω-substitutedoligothiophenes up to an undecamer with branched and linear alkyl chains, respectively, are presented. These series are compared with respect to self-organisation in solution and in solid state. UV/Vis absorption data for the long disubstituted branchedoligothiophenes indicate the formation of aggregates in solution, expressed by a bathochromic shift