Diode-Like I-V Characteristics of a Nonplanar Polyaromatic Compound: a Spectroscopic Study of Isolated and Stacked Dibenzo[g, p]chrysene

作者：Lee Shern Long; Huang Min Jie; Chen Chun hsien^*; Wang Cheng I; Liu Rai Shung

来源：Chemistry-An Asian Journal, 2011, 6(5): 1181-1187.

DOI：10.1002/asia.201000859

• electron transfer
• nanotechnology
• scanning-probe microscopy
• self-assembly
• stacking interactions

In this scanning-tunnelingmicroscopy/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 mu s 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 pi-stacked DBC molecules.

• 出版日期2011-5-2
• 单位清华大学