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Diode‐Like I – V Characteristics of a Nonplanar Polyaromatic Compound: a Spectroscopic Study of Isolated and Stacked Dibenzo[ g,p ]chrysene
Author(s) -
Lee ShernLong,
Huang MinJie,
Chen Chunhsien,
Wang ChengI,
Liu RaiShung
Publication year - 2011
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201000859
Subject(s) - chrysene , dbc , homo/lumo , molecule , materials science , scanning tunneling microscope , density functional theory , spectroscopy , chemistry , crystallography , photochemistry , nanotechnology , optoelectronics , computational chemistry , physics , organic chemistry , cmos , quantum mechanics , anthracene
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 ca. 7 V/10 μs 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.