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Over what length-scale can the substrate perturb the structure of a vapor-deposited organic glass?

ORAL

Abstract

Ultrathin (<30 nm) vapor-deposited layers are often utilized in OLED (organic light emitting diodes) devices. However, the vast majority of structural studies of vapor-deposited glasses have focused on films that are 100 nm or thicker. As a result these studies have not been sensitive to glass structure at the buried interface, which is of significance for OLED performance. Here we study, with grazing incidence x-ray scattering, the structure of vapor-deposited glasses of molecular glass former DSA-Ph as a function of film thickness. We span a thickness range of 10-600 nm. For films deposited on a Si/SiO2 substrate at ~ 0.8 Tg, we estimate that the region near the buried interface with qualitatively different packing is less than 4 nm. A coarse-grained Lennard-Jones model of DSA-Ph qualitatively reproduces the short interfacial length-scale observed experimentally, implying our results are broadly applicable to molecular glasses that form continuous films on deposition.

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Presenters

  • Kushal Bagchi

    University of Wisconsin - Madison, Chemistry, University of Wisconsin - Madison

Authors

  • Kushal Bagchi

    University of Wisconsin - Madison, Chemistry, University of Wisconsin - Madison

  • Chuting Deng

    University of Chicago

  • Camille Bishop

    Chemistry, University of Wisconsin - Madison, University of Wisconsin - Madison, Department of Chemistry, University of Wisconsin-Madison

  • Yuhui Li

    University of Wisconsin - Madison

  • Nicholas Jackson

    Pritzker School of Molecular Engineering, University of Chicago, University of Chicago

  • Michael Toney

    SLAC - Natl Accelerator Lab, SLAC National Accelerator Laboratory, SLAC Linear Accelerator Laboratory, Stanford Linear Accelerator Laboratory

  • Lian Yu

    University of Wisconsin - Madison

  • Juan De Pablo

    University of Chicago, Pritzker School of Molecular Engineering, University of Chicago, Institute for Molecular Engineering, University of Chicago. Argonne National Laboratory, Pritzker School of Molecular Engineerin, The University of Chicago, Molecular Engineering, University of Chicago

  • Mark Ediger

    University of Wisconsin - Madison, Chemistry, University of Wisconsin - Madison, Department of Chemistry, University of Wisconsin-Madison