Abstract
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.
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ACKNOWLEDGMENTS
We gratefully acknowledge the financial support of the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) and we thank the Paul Scherrer Institute for providing excellent facilities at the material science beam line MS-X04SA of the Swiss Light Source. C.L. and G.D. acknowledge financial support from the Carl-Zeiss-Stiftung. In addition, this research has been partly supported by JSPS KAKENHI (No. 24245034), by Grant-in-Aid for JSPS Research Fellow (15J08155) and by Global COE program (G-03, MEXT).
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Reisz, B., Weimer, S., Banerjee, R. et al. Structural, optical, and electronic characterization of perfluorinated sexithiophene films and mixed films with sexithiophene. Journal of Materials Research 32, 1908–1920 (2017). https://doi.org/10.1557/jmr.2017.99
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DOI: https://doi.org/10.1557/jmr.2017.99