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Supramolecular organization in ultra-thin films of α-sexithiophene on silicon dioxide

Nature Materials volume 4, pages 81–85 (2005)Cite this article

Abstract

The supramolecular organization of organic semiconductors on the dielectric layer of thin-film field-effect transistors is a crucial factor in achieving good device performance. Charge transport in these devices occurs near the interface with the gate dielectric. By confocal spectroscopy and microscopy we study the supramolecular organization in ultra-thin films of a prototype organic semiconductor, α-sexithiophene, on silicon dioxide, a widely used transistor gate dielectric. We demonstrate that in submonolayer films of sexithiophene (T6), regions where the molecules stand on their long molecular axis coexist with regions where the molecules lie flat on the substrate. When the first monolayer is completed, all T6 molecules stand on the substrate, and the flat molecules detected in the submonolayer films are no longer present. In films thicker than two monolayers, the photoluminescence spectra of standing molecules show a molecular H-like aggregation as in the single crystal.

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Figure 1: Topography and CLSM photoluminescence images of T6 submonolayer films.
Figure 2: CLSM photoluminescence image and spatially resolved PL spectra of a T6 ultra-thin film.
Figure 3: Comparison of the PL spectra of T6 in different aggregation forms, and the supramolecular organization of T6 submonolayer.
Figure 4: Multilayer films.

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Acknowledgements

The valuable technical support of P. Fancello, P. Mei and T. Bonfiglioli is kindly acknowledged. We thank C. Taliani for useful discussions. Work was supported by the EU FET-IST program under contract IST-2001-33057 (ILO), IST-2001-38919 (PHOENIX) and by EU-G5RD-CT2000-00349 (MONA-LISA).

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  1. Istituto per lo Studio dei Materiali Nanostrutturati (ISMN)- Sezione di Bologna, Consiglio Nazionale delle Ricerche, via P. Gobetti 101, Bologna, I-40129, Italy

    Maria Antonietta Loi, Enrico da Como, Franco Dinelli, Mauro Murgia, Roberto Zamboni, Fabio Biscarini & Michele Muccini

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  1. Maria Antonietta Loi
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Correspondence to Maria Antonietta Loi or Michele Muccini.

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Loi, M., da Como, E., Dinelli, F. et al. Supramolecular organization in ultra-thin films of α-sexithiophene on silicon dioxide. Nature Mater 4, 81–85 (2005). https://doi.org/10.1038/nmat1279

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