Interlayer resistance and edge-specific charging in layered molecular crystals revealed by Kelvin-probe force microscopy

Yuji Yamagishi, Kei Noda, Kei Kobayashi, Hirofumi Yamada

    Research output: Contribution to journalArticle

    17 Citations (Scopus)

    Abstract

    Organic field-effect transistors (OFETs) having an active channel of solution-processed 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) were investigated by Kelvin-probe force microscopy (KFM). We found step-like potential distributions in a channel region, suggesting that the interlayer resistance between the conjugated BTBT core layers is quite high and each conjugated layer is electrically isolated from one another by insulating alkyl chain layers. We also found a noticeable positive charging in the channel region especially at the step edges after the device operation. The observed charging was explained by long-lived positive charges on the trap sites, and the trap density at the step edge was estimated to be on the order of 1011 cm-2. The KFM measurements suggest that the device performance of the staggered C8-BTBT OFETs could deteriorate due to the considerably high access resistance, which stems from the high interlayer resistance and/or by the site-specific charge trapping at the contact/semiconductor interface which originates from step edge structures.

    Original languageEnglish
    Pages (from-to)3006-3011
    Number of pages6
    JournalJournal of Physical Chemistry C
    Volume119
    Issue number6
    DOIs
    Publication statusPublished - 2015 Feb 12

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Energy(all)
    • Physical and Theoretical Chemistry
    • Surfaces, Coatings and Films

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