Enhanced charge transfer in a monolayer of the organic charge transfer complex TTF–TNAP on Au(111)
Enhanced charge transfer in a monolayer of the organic charge transfer complex TTF–TNAP on Au(111)
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DOI：
10.1088/0953-8984/24/35/354003
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发表时间：
2012-09
期刊：
影响因子：
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通讯作者：
T. Umbach;I. Fernández-Torrente;Janina N. Ladenthin;J. Pascual;K. Franke;K. Franke
中科院分区：
文献类型：
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作者：
T. Umbach;I. Fernández-Torrente;Janina N. Ladenthin;J. Pascual;K. Franke;K. Franke
电子掺杂是调整有机材料性能的关键概念。在体结构中，供体和受体之间的电荷转移主要由各自的电离势和电子亲和力决定。相反，与金属接触的单层电荷转移配合物受到金属界面杂化和筛选的有趣相互作用的影响，从而决定了产生的电荷状态。利用扫描隧道显微镜和光谱学，研究了吸附在Au（111）表面的有机受体分子11,11,12,12-四氰萘醌-2,6-喹诺二甲烷（TNAP）的电子性质。有序岛保持弱物理吸收状态，与底物无电荷转移相互作用。当加入电子供体四硫代丙烯（TTF）时，由TNAP行和TTF行交替排列的有序阵列组装起来。在这些结构中，我们发现自由TNAP分子的最低未占据分子轨道（LUMO）远低于底物的费米能级。因此，TNAP带有不止一个电子。
Electronic doping is a key concept for tuning the properties of organic materials. In bulk structures, the charge transfer between donor and acceptor is mainly given by the respective ionization potential and electron affinity. In contrast, monolayers of charge transfer complexes in contact with a metal are affected by an intriguing interplay of hybridization and screening at the metallic interface, determining the resulting charge state. Using scanning tunneling microscopy and spectroscopy, we characterize the electronic properties of the organic acceptor molecule 11,11,12,12-tetracyanonaptho-2,6-quinodimethane (TNAP) adsorbed on a Au(111) surface. The ordered islands remain in a weakly physisorbed state with no charge transfer interaction with the substrate. When the electron donor tetrathiafulvalene (TTF) is added, ordered arrays of alternating TNAP and TTF rows are assembled. In these structures, we find the lowest unoccupied molecular orbital (LUMO) of the free TNAP molecule shifted well below the Fermi level of the substrate. The TNAP is thus charged with more than one electron.