Lyu Lu, Niu Dongmei, Xie Haipeng, Cao Ningtong, Zhang Hong, Zhang Yuhe, Liu Peng, Gao Yongli
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, People's Republic of China.
J Chem Phys. 2016 Jan 21;144(3):034701. doi: 10.1063/1.4939839.
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.
结合紫外光电子能谱、X射线光电子能谱、原子力显微镜和X射线衍射测量，我们对2,7-二辛基[1]苯并噻吩并[3,2-b]苯并噻吩（C8-BTBT）在高度取向热解石墨上的能级排列、薄膜生长和分子取向之间的相关性进行了系统研究。分子在第一层平躺，从第二层开始直立。电离势从平躺区域到直立区域急剧下降。当C8-BTBT分子开始直立时，随着薄膜厚度增加，观察到非常规的类似能级带弯曲的位移。这些位移归因于分子相对于衬底法线的倾斜角随着薄膜厚度增加而逐渐减小。
