Chen Min, Zhou Han, Klein Benedikt P, Zugermeier Malte, Krug Claudio K, Drescher Hans-Jörg, Gorgoi Mihaela, Schmid Martin, Gottfried J Michael
Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany.
Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein Str. 15, 12489 Berlin, Germany.
Phys Chem Chem Phys. 2016 Nov 9;18(44):30643-30651. doi: 10.1039/c6cp05894a.
The interface formation upon vapor deposition of a metal onto a molecular organic semiconductor was studied using a well-defined complexation reaction between a metal and a porphyrin. Specifically, metallic cobalt (Co) was vapor deposited onto a thin film of 2H-tetraphenylporphyrin (2HTPP) at room temperature. The resulting interface was probed with Hard X-ray Photoelectron Spectroscopy (HAXPES) using photon energies between 2 and 6 keV to obtain a detailed depth profile of the chemical composition. Characteristic changes in the N 1s core level signals reveal the formation of a cobalt tetraphenylporphyrin (CoTPP) layer between the Co and 2HTPP layers. Assuming an abrupt interface between CoTPP and 2HTPP (layer-by-layer model), analysis of the XPS data results in a thickness of the CoTPP reaction layer of 1.6 nm. However, a more advanced numerical analysis allowed us to reconstruct details of the actual depth distribution of the CoTPP interphase layer: up to a depth of 1.5 nm, all 2HTPP molecules were converted into CoTPP. Beyond this depth, the CoTPP concentration decreases sharply within 0.15 nm to zero.
利用金属与卟啉之间明确的络合反应，研究了金属气相沉积到分子有机半导体上时的界面形成情况。具体而言，在室温下将金属钴（Co）气相沉积到2H-四苯基卟啉（2HTPP）薄膜上。使用2至6 keV之间的光子能量，通过硬X射线光电子能谱（HAXPES）对所得界面进行探测，以获得化学成分的详细深度分布。N 1s核心能级信号的特征变化揭示了在Co层和2HTPP层之间形成了钴四苯基卟啉（CoTPP）层。假设CoTPP和2HTPP之间存在突变界面（逐层模型），对XPS数据的分析得出CoTPP反应层的厚度为1.6 nm。然而，更先进的数值分析使我们能够重建CoTPP界面层实际深度分布的细节：在深度达1.5 nm时，所有2HTPP分子都转化为CoTPP。超过这个深度，CoTPP浓度在0.15 nm内急剧下降至零。
