Impact of an interface dipole layer on molecular level alignment at an organic-conductor interface studied by ultraviolet photoemission spectroscopy
Impact of an interface dipole layer on molecular level alignment at an organic-conductor interface studied by ultraviolet photoemission spectroscopy
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DOI：
10.1103/physrevb.70.085304
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发表时间：
2004-08-01
影响因子：
3.7
通讯作者：
Ueno, N
中科院分区：
文献类型：
--
作者：
Kera, S;Yabuuchi, Y;Ueno, N
用紫外光电子能谱(UPS)和亚稳原子电子能谱研究了铜酞菁(CuPc)单分子膜/电偶极层/石墨体系中界面偶极层对有机导体界面能级取向的影响。在石墨上生长具有电偶极矩的定向的OTI-酞菁分子单分子层，以产生真空侧带负电荷的明确的偶极层。CuPc单层有序地沉积在保持在123K的偶极层上，这个由非常薄的有机层和非常薄的偶极层组成的弱相互作用体系处于热力学平衡状态。有界面偶极层生长和不有界面偶极层生长的系统的UPS数据表明，当插入偶极层时，CuPc单分子膜最高占据态的结合能降低。结合能的移动与偶极层沉积时石墨衬底真空度的增加是一致的。结果表明，当插入界面偶极层时，CuPc的费米能级向价态移动。
The effect of an interface dipole layer on the energy level alignment at organic-conductor interfaces is studied on a copper phthalocyanine (CuPc) monolayer/electric dipole layer/graphite system via ultraviolet photoemission spectroscopy (UPS) and metastable atom electron spectroscopy. An oriented monolayer of the OTi-phthalocyanine molecule, which has an electric dipole moment, is grown on graphite to yield a well-defined dipole layer with the vacuum side negatively charged. The CuPc monolayer is sequentially deposited on the dipole layer kept at 123 K. This weakly interacting system made of a very thin organic layer on top of a very thin dipole layer is in thermodynamic equilibrium. The UPS data from the system grown with and without the interface dipole layer show that the binding energy of the highest occupied state of the CuPc monolayer decreases when the dipole layer is inserted. The binding energy shift is in excellent agreement with the increase in vacuum level energy of the graphite substrate upon deposition of the dipole layer. The results show that the Fermi level of the CuPc shifts toward the valence states when the interface dipole layer is inserted.