title: Advanced Photoemission Spectroscopy Investigations Correlated with DFT Calculations on the Self-Assembly of 2D Metal Organic Frameworks Nano Thin Films.
abstract: 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.
authors: Department of Electrical Engineering, University of South Florida , Tampa, Florida 33620, United States.
authors: Radwan
authors: R
authors: Elzein
authors: Department of Physics, University of South Florida , Tampa, Florida 33620, United States.|Institute for Cyber-Enabled Research, Michigan State University , East Lansing, Michigan 48824, United States.
authors: Chun-Min
authors: CM
authors: Chang
authors: Department of Physics, University of South Florida , Tampa, Florida 33620, United States.
authors: Inna
authors: I
authors: Ponomareva
authors: Department of Chemistry, University of South Florida , Tampa, Florida 33620, United States.
authors: Wen-Yang
authors: WY
authors: Gao
authors: Department of Chemistry, University of South Florida , Tampa, Florida 33620, United States.
authors: Shengqian
authors: S
authors: Ma
authors: Department of Electrical Engineering, University of South Florida , Tampa, Florida 33620, United States.
authors: Rudy
authors: R
authors: Schlaf
keywords: 2D thin films; DFT calculations; density of states; metal−organic frameworks; photoemission spectroscopy; supramolecular self-assembly; surface science