Department of Electrical Engineering, University of South Florida , Tampa, Florida 33620, United States.
Department of Physics, University of South Florida , Tampa, Florida 33620, United States.
ACS Appl Mater Interfaces. 2016 Nov 16;8(45):31403-31412. doi: 10.1021/acsami.6b10340. Epub 2016 Nov 3.
Metal-organic frameworks (MOFs) deposited from solution have the potential to form 2-dimensional supramolecular thin films suitable for molecular electronic applications. However, the main challenges lie in achieving selective attachment to the substrate surface, and the integration of organic conductive ligands into the MOF structure to achieve conductivity. The presented results demonstrate that photoemission spectroscopy combined with preparation in a system-attached glovebox can be used to characterize the electronic structure of such systems. The presented results demonstrate that porphyrin-based 2D MOF structures can be produced and that they exhibit similar electronic structure to that of corresponding conventional porphyrin thin films. Porphyrin MOF multilayer thin films were grown on Au substrates prefunctionalized with 4-mercaptopyridine (MP) via incubation in a glovebox, which was connected to an ultrahigh vacuum system outfitted with photoelectron spectroscopy. The thin film growth process was carried out in several sequential steps. In between individual steps the surface was characterized by photoemission spectroscopy to determine the valence bands and evaluate the growth mode of the film. A comprehensive evaluation of X-ray photoemission spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and inverse photoemission spectroscopy (IPES) data was performed and correlated with density functional theory (DFT) calculations of the density of states (DOS) of the films involved to yield the molecular-level insights into the growth and the electronic properties of MOF-based 2D thin films.
金属-有机骨架（MOFs）从溶液中沉积具有形成适用于分子电子应用的二维超分子薄膜的潜力。然而，主要的挑战在于实现与基底表面的选择性附着，以及将有机导电配体整合到 MOF 结构中以实现导电性。所呈现的结果表明，光电发射光谱学结合在系统附着手套箱中的制备可用于表征此类系统的电子结构。所呈现的结果表明，可以生产基于卟啉的二维 MOF 结构，并且它们表现出与相应的常规卟啉薄膜相似的电子结构。通过在手套箱中孵育，将预先官能化有 4-巯基吡啶（MP）的 Au 基底上生长卟啉 MOF 多层薄膜，该手套箱连接到配备光电电子能谱的超高真空系统。薄膜生长过程分几个连续步骤进行。在各个步骤之间，通过光电子能谱法对表面进行特征化，以确定价带并评估薄膜的生长模式。对 X 射线光电子能谱（XPS）、紫外光电子能谱（UPS）和反光电发射谱（IPES）数据进行了全面评估，并与涉及的薄膜的密度泛函理论（DFT）计算的态密度（DOS）相关联，以提供对 MOF 基二维薄膜的生长和电子特性的分子水平的深入了解。
