Berlin 2012 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 44: Poster IV: Thin film photovoltaics; Organic electronics and photovoltaics (jointly with CPP, HL, O); Organic thin films; Trends in atomic layer deposition (Focused session)

DS 44.44: Poster

Freitag, 30. März 2012, 09:30–12:00, Poster E

In situ X-ray diffraction on mixed pentacene - perfluoropentacene thin films — •Christian Frank¹, Jiří Novák¹, Alexander Gerlach¹, Alexander Hinderhofer¹, Roberto Nervo², Katharina Broch¹, Giovanni Ligorio¹, and Frank Schreiber¹ — ¹Institut für Angwandte Physik, Universität Tübingen, Germany — ²ESRF, Grenoble, France

Using X-ray diffraction [1] and optical spectrocopy [2] we have studied binary mixtures on SiO_x, consisting of pentacene (PEN) and perfluorinated-pentacene (PFP). For films with different mixing ratios we investigate the coexistence of the two mixed PEN:PFP phases together with the phases of the pure molecules. We show, that the σ-phase, with its long molecular axis oriented nearly perpendicular to the substrate is thermally stable, whereas the appearance of the λ-phase with its molecules lying flat, is induced by low temperatures. Based on previous results [1,3], the growth of these films is studied in real-time to measure the evolution of the coherent island size for both phases: We find that for PFP₁:PEN₂-mixtures the nucleation of the λ-phase is significantly retarded compared to PFP₂:PEN₁-mixtures. The study is complemented with a temperature series of pure PFP and post-growth measurements. [1] A. Hinderhofer, C. Frank, T. Hosokai, A. Resta, A. Gerlach, and F. Schreiber, J. Chem. Phys. 134 (2011), 104702. [2] K. Broch, U. Heinemeyer, A. Hinderhofer, F. Anger, R. Scholz, A. Gerlach, and F. Schreiber, Phys. Rev. B 83 (2011), 245307. [3] S. Kowarik, A. Gerlach, S. Sellner, F. Schreiber, L. Cavalcanti, and O. Konovalov, Phys. Rev. Lett. 96 (2006), 125504.