Orientation-dependent energy level alignment and film growth of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on HOPG

Journal Article · Thu Jan 21 04:00:00 EST 2016 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4939839· OSTI ID:22493670

Lyu, Lu; Niu, Dongmei; Xie, Haipeng; Cao, Ningtong; Zhang, Hong; Zhang, Yuhe; Liu, Peng ^[1]; Gao, Yongli ^[1]

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1. Institute of Super-Microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University, No. 605 Lushan South Road, Changsha, Hunan 410012 (China)

Combining ultraviolet photoemission spectroscopy, X-ray photoemission spectroscopy, atomic force microscopy, and X-ray diffraction measurements, we performed a systematic investigation on the correlation of energy level alignment, film growth, and molecular orientation of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on highly oriented pyrolytic graphite. The molecules lie down in the first layer and then stand up from the second layer. The ionization potential shows a sharp decrease from the lying down region to the standing up region. When C8-BTBT molecules start standing up, unconventional energy level band-bending-like shifts are observed as the film thickness increases. These shifts are ascribed to gradual decreasing of the molecular tilt angle about the substrate normal with the increasing film thickness.

• OSTI ID: 22493670
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 3 Vol. 144; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ATOMIC FORCE MICROSCOPY
CORRELATIONS
ENERGY LEVELS
FILMS
GRAPHITE
LAYERS
MOLECULES
ORIENTATION
PHOTOELECTRON SPECTROSCOPY
POTENTIALS
SUBSTRATES
THIONAPHTHENES
THIOPHENE
ULTRAVIOLET RADIATION
X-RAY DIFFRACTION