We report on the growth and characterization of molecular mixed thin films of α-sexithiophene (6T), a well-known organic p-type semiconductor with high hole mobility, together with its perfluorinated counterpart, the so far rarely studied tetradecafluoro-α-sexithiophene (PF6T). Pure and blended thin films of these two molecules with different mixing ratios were grown on silicon oxide in ultrahigh vacuum by coevaporation. The effect of perfluorination and mixing on crystal structure, morphology, electronic, and optical properties was examined. The evolution of the PF6T crystal structure was followed in situ in real time by X-ray scattering. We found a new thin film structure different from the reported bulk phase with molecules either standing-up or lying-down depending on the growth temperature. The different morphologies of pure films and blends were investigated with atomic force microscopy. The impact of mixing on the core-levels and on the highest occupied molecular orbitals of 6T and PF6T is discussed.

Surface-induced aromatic stabilization (SIAS), a recently proposed mechanism leading to a formation of charge-transfer (CT) states at organic/metal (O/M) interfaces [G. Heimel, et al., Nat. Chem.5, 187 (2013)], was investigated for an aromatic hydrocarbon, diindenoperylene (DIP), by means of synchrotron radiation-based ultraviolet photoelectron spectroscopy (UPS). By employing DIP and noble metal substrates (Ag and Cu), we confirmed the formation of CT states, indicating that an inclusion of a specific functional group with a hetero-atom within adsorbate molecules as suggested before is not necessarily required for the formation of CT states mediated by the SIAS. With a comparison of the mother and analogue molecules, perylene and PTCDA, we discuss the structural requirement for the realization of the SIAS.

Optical properties and thermal properties of self-polarized thin PZT films were determined by variable angle spectral ellipsometry and by the AC hot strip method, respectively. Analyzing the temperature dependencies of the optical gap and the specific heat, evidence of two not as yet observed phase transitions in the ferroelectric was provided. The origin of these phase transitions was attributed to film stress caused by substrate/PZT thin film lattice mismatch and to the presence of a negative space charge layer in the PZT film at the bottom electrode/PZT interface.