Contact Angle Behavior for Fullerene/Porphyrin Mixtures on Si surfaces

ORAL

Abstract

Fullerene/porphyrin mixtures are of great interest in bulk heterojunction organic solar cells. Here we study the morphology of the phase separation which occurs when [6,6]-phenyl-C$_{61}$-butyric acid methyl ester (PCBM) and tetranitro-zinc phthalocyanine (tn-ZnPc), are deposited onto silicon (111) substrates, including the individual domain length scales, shapes and wetting angles. tn-ZnPC forms small clusters on the Si surface with a contact angle of approximately 15\r{ }, while PCBM forms compact clusters on broad ($\sim $0.5 um diameter) ``wetting-layer'' disks, with the cluster contact angle of $\sim $19\r{ }. Interestingly, a 50{\%} mixture shows topography qualitatively similar to that for PCBM, but with a larger contact angle of 22\r{ }, indicating that the mixture wets the interface less than either pure component alone.

*Work supported by the NSF-MRSEC at the University of Maryland \#DMR0520471.

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Authors

  • Miriam Cezza

    • Department of Materials Science and Engineering, University of Maryland, MD, 20742

  • Romaine A. Isaacs

    • Department of Materials Science and Engineering, University of Maryland, MD, 20742

  • Qian Shao

    • Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, 20742

  • Shy-Hauh Guo

    • Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742
    • Department of Materials Science and Engineering, University of Maryland, MD, 20742

  • Lourdes G. Salamanca-Riba

    • Materials Science and Engineering Department, University of Maryland, College Park, MD
    • University of Maryland - College Park
    • Department of Materials Science and Engineering, University of Maryland, MD, 20742

  • Janice Reutt Robey

    • Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, 20742
    • University of Maryland

  • Raymond J. Phaneuf

    • Department of Materials Science and Engineering, University of Maryland, MD, 20742