Commensurism at electronically weakly interacting phthalocyanine/PTCDA heterointerfaces
Commensurism at electronically weakly interacting phthalocyanine/PTCDA heterointerfaces
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DOI：
10.1103/physrevb.91.155432
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发表时间：
2015-04-28
影响因子：
3.7
通讯作者：
Fritz, Torsten
中科院分区：
文献类型：
--
作者：
Gruenewald, Marco;Sauer, Christoph;Fritz, Torsten
多层电子器件中的界面是至关重要的，特别是对于纳米范围内的层厚度。在界面过程中的电荷注入或提取和激子解离，后者是特别相关的，如果分子成分参与。高度有序的超结构是优选的，以防止电荷载流子和/或激子的不期望的损失。外延有机-无机系统已经受到广泛关注，但迄今为止只有很少的研究涉及有机-有机异质界面。本文研究了金属酞菁（MePc，Me = Sn或Cu）在3，4，9，10-二萘嵌苯四甲酸二酐（PTCDA）表面的吸附行为。使用扫描隧道显微镜和低能电子衍射，我们揭示了一个初始的无序生长稀释SnPc亚单层和连续三个凝聚相的覆盖范围高达1毫升，每个拥有一个独特的相称注册表与底层PTCDA。通过应用原位光学微分反射光谱和光电子能谱，我们发现，无论是SnPc还是CuPc相表现出显着的电子或光学耦合与PTCDA中间层。因此，我们的研究结果表明，吸附不一定意味着化学吸附，如文献中所述，但物理吸附可能伴随着相称的超结构。
Interfaces in multilayered electronic devices are of paramount importance, especially for layer thicknesses in the nanometer range. Among the interfacial processes are charge injection or extraction and excitonic dissociation, the latter being particularly relevant if molecular components are involved. Highly ordered superstructures are preferable to prevent undesired losses of charge carriers and/or excitons. Epitaxial organic-inorganic systems have already received eminent attention, but only few studies have dealt with organic-organic heterointerfaces so far. Here, we focus on the adsorption of metal-phthalocyanines (MePc, Me = Sn or Cu) on 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) in the form of stacked monolayers (ML) on Ag(111). Using scanning tunneling microscopy and low-energy electron diffraction we reveal an initial nonordered growth for dilute SnPc submonolayers and consecutively three condensed phases at coverages ranging up to 1 ML-each possessing a distinct commensurate registry with the underlying PTCDA. By applying in situ optical differential reflectance spectroscopy and photoelectron spectroscopy we find that neither the SnPc nor the CuPc phases exhibit significant electronic or optical coupling with the PTCDA interlayer. Therefore, our results demonstrate that commensurism does not necessarily imply chemisorption, as stated previously in the literature, but that physisorption may be accompanied by commensurate superstructures.