Aggregate formation in dialkoxyphenylene-thiophene oligomers were investigated experimentally by atomic force microscopy, absorption and by steady-state photoluminescence at room and at low temperatures. Aggregate features were observed to occur in solutions and solid state films. Depending on the solvent, temperature and excitation power, aggregate bands at different wavelength ranges appear in the emission spectra, indicating that different aggregate species are involved. Despite many experimental results involving aggregated states in the literature, in this work the experimental results are shown to have a direct correlation with theoretical achievements. (C) 2014 Elsevier B.V. All rights reserved.