Abstract
Looking for single molecule electronic devices, we have investigated the charge transport properties of individual tetra-phenylporphyrin molecules on different substrates by ultrahigh-vacuum scanning tunneling microscopy and spectroscopy and by first-principles calculations. The tetra-phenylporphyrins with a Co atom (Co-TPP) or 2 hydrogens (H2-TPP) in the central macrocycle when deposited on Cu3Au(100) substrates showed a diode-like behavior with p and n type character, respectively. After removing the central hydrogens of H2-TPP molecule with the STM tip an ohmic behavior was measured. The rectifying effect was understood from the theoretical point of view by assuming for Co-TPP HOMO conduction and for H2-TPP LUMO conduction, both selectively elected by the hybridization of states between molecule and substrate surface.
Highlights
Looking for single molecule electronic devices, we have investigated the charge transport properties of individual tetra-phenylporphyrin molecules on different substrates by ultrahigh-vacuum scanning tunneling microscopy and spectroscopy and by first-principles calculations
The rectifying effect was understood from the theoretical point of view by assuming for Co-TPP highest occupied molecular orbital (HOMO) conduction and for H2-TPP LUMO conduction, both selectively elected by the hybridization of states between molecule and substrate surface
Lei and co-authors[7] demonstrate by Low Temperature Scanning Tunneling Microscopy (LT-STM) measurements and Density Functional Theory (DFT) simulations a orbital-selective rectifier effect for single cobalt phthalocyanine (CoPc) molecules adsorbed on graphene-covered Ru(0001) surface
Summary
Correspondence and requests for materials should be addressed to A.A.P. The tetra-phenylporphyrins with a Co atom (Co-TPP) or 2 hydrogens (H2-TPP) in the central macrocycle when deposited on Cu3Au(100) substrates showed a diode-like behavior with p and n type character, respectively. The charge transport properties of individual tetra-phenylporphyrin molecules on different substrates were studied by Ultrahigh-Vacuum Scanning Tunneling Microscopy and Scanning Tunneling Spectroscopy (UHV-STM/STS) measurements. Porphyrins are interesting molecules due to their variety of functional properties, which are relevant for biological and artificial systems[9] This versatile molecule can be synthesized with a wide diversity of meso-substituents and can host different metals in the core macrocycle[10,11,12]. In this combined experimental and theoretical study, we observed that the tetra-phenylporphyrins with a Co atom (Co-TPP) or 2 hydrogens (H2-TPP) in the central macrocycle, when deposited on Cu3Au(100) substrates, show diode-like behavior with p and n type character,respectively. We were able to manipulate the H2-TPP electrical response by removing the central hydrogens
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