Diode-Like I-V Characteristics of a Nonplanar Polyaromatic Compound: a Spectroscopic Study of Isolated and Stacked Dibenzo[g, p]chrysene
Resource
CHEMISTRY-AN ASIAN JOURNAL, 6(5), 1181-1187
Journal
Chemistry-An Asian Journal
Journal Volume
6
Journal Issue
5
Pages
1181-1187
Date Issued
2011
Date
2011
Author(s)
Abstract
In this scanning-tunneling-microscopy/spectroscopy study (STM/STS), samples of isolated and close-packed dibenzo[g,p]chrysene (DBC), a nonplanar polyaromatic compound, are used as model systems to demonstrate the effect of intermolecular interactions on the electronic structures. For dropcast films, DBC molecules adopt an edge-on orientation in a close-packed structure on graphite. Isolated DBC molecules are prepared on graphite from a DBC-coated STM tip by a ca7 V/10 νs pulse. STS spectra for both isolated- and close-packed DBC molecules exhibit diode-like I-V curves in which the latter shows a turn-on voltage (0.47 V) smaller than that of the former (0.91 V). The diode-like behaviors are attributed to the more-facile tunneling of electrons through the HOMO of DBC than through the LUMO. The reduced turn-on voltage for the films is ascribed to the diminished HOMO-LUMO gap based on the results of DFT (density functional theory) simulations for the energy-level couplings of π-stacked DBC molecules. Electric Rectification: DBC (dibenzo[g,p]chrysene), an all hydrocarbon polyaromatic compound, exhibits diode-like I-V behavior that is significantly enhanced by intermolecular πi-π stacking. This electric rectification is attributed to orbital-mediated tunneling through the HOMO levels of DBC. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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journal article
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