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.

*This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, Award DE-SC000216.

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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