Thin films of quaterthiophenes having extra bulky terminal groups were fabricated either by vacuum evaporation or by casting solution containing the material. Morphological and spectroscopic features of these thin films were studied by X-ray diffraction, IR, Raman, and UV-visible measurements. The subtle modification in the bulky terminal groups causes not only a change in the conformation of the quaterthiophene backbone, but also a change in the overall morphology of the thin films which can be described in terms of polymorphism. The spectroscopic characteristics reflecting the difference in the backbone conformation are presented and discussed.