Surface-Directed Molecular Assembly of Pentacene

 

Organophosphonate self-assembled monolayers (SAMPs) fabricated on SiO2 surfaces can influence crystallization of vapor-deposited pentacene, and thus can affect device performance of pentacene-based organic thin film transistors. Polarized Raman spectroscopy is demonstrated to be an effective technique to determine the degree of anisotropy in pentacene thin films deposited on structurally different, aromatic SAMPs grown on silicon oxide dielectrics. Grain sizes of pentacene crystallites grown on bare SiO2 dielectric are larger than those grown on SAMPs. However, the transport characteristics of pentacene thin film transistors based on inferior, commercial Si/SiO2 substrates are drastically improved by SAMP dielectric functionalization. Vibrational characterization of pentacene molecules in these films reveals that the molecular orientation of adjacent crystalline grains is strongly correlated on the SAMP-modified dielectric surface, which results in enhanced interconnectivity between the crystallite domains, well beyond the size of a single grain. Through AFM, X-ray analysis, Raman spectroscopy, and electrical characterization we can show that aromatic organophosphonate monolayers can act as effective nucleation sites for the crystallization of pentacene and can influence molecular microstructure and intermolecular interactions in the deposited pentacene thin films.

Selected Publications:

Yazji S.; Westermeier C.; Weinbrenner D.; Sachsenhauser M.; Liao K-C.; Noever S.; Postorino P.; Schwartz J.; Abstreiter G.; Nickel B.; Zardo I.; Cattani-Scholz A. " Surface-Directed Molecular Assembly of Pentacene on Aromatic Organophosphonate Self-Assembled Monolayers Explored by Polarized Raman Spectroscopy", 2016, Journal of Raman Spectroscopy, accepted.

Collaborations:

Ilaria Zardo, Department of Physics, University of Basel, Switzerland

Bert Nickel, Fakultät für Physik and Center for NanoScience, Ludwig-Maximilians-Universität München, Germany

Open Positions:

if you would like to join us as an internship or master student on this project, please contact Anna Cattani-Scholz

TUM Technische Universität München TUM Technische Universität München Physik Department Elektrotechnik und Informationstechnik TUM Technische Universität München
 

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