High quality alpha-oligothiophene films grown by supersonic seeded beams: Optical, morphological and structural characterization

A novel approach to the deposition of high quality films of oligothiophenes has been developed. It is based on an original seeded supersonic molecular beam combined with an ultra high vacuum deposition chamber. This method gives an unprecedented control on film properties. Several quaterthiophene films under different beam conditions have been prepared and characterized by optical absorption, photoluminescence, tapping mode atomic force microscopy, secondary electron microscopy and X-ray diffraction. Morphology, structure and optical response are controlled by the beam's parameters. Highly ordered films, up to several hundreds of nm thick, show well resolved vibronic structures in low temperatures fluorescence spectra as only the best published data on films a few monolayers thick do.