1
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Zelovich T, Hansen T, Tuckerman ME. A Green's Function Approach for Determining Surface Induced Broadening and Shifting of Molecular Energy Levels. Nano Lett 2022; 22:9854-9860. [PMID: 36525585 DOI: 10.1021/acs.nanolett.2c02910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Upon adsorption of a molecule onto a surface, the molecular energy levels (MELs) broaden and change their alignment. This phenomenon directly affects electron transfer across the interface and is, therefore, a fundamental observable that influences electrochemical device performance. Here, we propose a rigorous parameter-free framework, built upon the theoretical construct of Green's functions, for studying the interface between a molecule and a bulk surface and its effect on MELs. The method extends beyond the usual wide-band limit approximation, and its generality allows its use with any level of electronic structure theory. We demonstrate its ability to predict the broadening and shifting of MELs as a function of intramolecular coupling, molecule/surface coupling, and the surface density of states for a molecule with two MELs adsorbed on a one-dimensional model metal surface. The new approach could help provide guidelines for the design and experimental characterization of electrochemical devices with optimal electron transport.
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Affiliation(s)
- Tamar Zelovich
- Department of Chemistry, New York University (NYU), New York, New York10003, United States
| | - Thorsten Hansen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100Copenhagen Ø, Denmark
| | - Mark E Tuckerman
- Department of Chemistry, New York University (NYU), New York, New York10003, United States
- Courant Institute of Mathematical Sciences, New York University (NYU), New York, New York10003, United States
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, 3663 Zhongshan Road North, Shanghai200062, China
- Simons Center for Computational Physical Chemistry, New York University, New York, New York10003, United States
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2
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Hurdax P, Kern CS, Boné TG, Haags A, Hollerer M, Egger L, Yang X, Kirschner H, Gottwald A, Richter M, Bocquet F, Soubatch S, Koller G, Tautz FS, Sterrer M, Puschnig P, Ramsey MG. Large Distortion of Fused Aromatics on Dielectric Interlayers Quantified by Photoemission Orbital Tomography. ACS Nano 2022; 16:17435-17443. [PMID: 36239301 PMCID: PMC9620409 DOI: 10.1021/acsnano.2c08631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 10/12/2022] [Indexed: 06/16/2023]
Abstract
Polycyclic aromatic compounds with fused benzene rings offer an extraordinary versatility as next-generation organic semiconducting materials for nanoelectronics and optoelectronics due to their tunable characteristics, including charge-carrier mobility and optical absorption. Nonplanarity can be an additional parameter to customize their electronic and optical properties without changing the aromatic core. In this work, we report a combined experimental and theoretical study in which we directly observe large, geometry-induced modifications in the frontier orbitals of a prototypical dye molecule when adsorbed on an atomically thin dielectric interlayer on a metallic substrate. Experimentally, we employ angle-resolved photoemission experiments, interpreted in the framework of the photoemission orbital tomography technique. We demonstrate its sensitivity to detect geometrical bends in adsorbed molecules and highlight the role of the photon energy used in experiment for detecting such geometrical distortions. Theoretically, we conduct density functional calculations to determine the geometric and electronic structure of the adsorbed molecule and simulate the photoemission angular distribution patterns. While we found an overall good agreement between experimental and theoretical data, our results also unveil limitations in current van der Waals corrected density functional approaches for such organic/dielectric interfaces. Hence, photoemission orbital tomography provides a vital experimental benchmark for such systems. By comparison with the state of the same molecule on a metallic substrate, we also offer an explanation why the adsorption on the dielectric induces such large bends in the molecule.
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Affiliation(s)
- Philipp Hurdax
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Christian S. Kern
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Thomas Georg Boné
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Anja Haags
- Peter
Grünberg Institute (PGI-3), Forschungszentrum
Jülich, 52425Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals
of Future Information Technology, 52425Jülich, Germany
- Experimentalphysik
IV A, RWTH Aachen University, 52074Aachen, Germany
| | - Michael Hollerer
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Larissa Egger
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Xiaosheng Yang
- Peter
Grünberg Institute (PGI-3), Forschungszentrum
Jülich, 52425Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals
of Future Information Technology, 52425Jülich, Germany
- Experimentalphysik
IV A, RWTH Aachen University, 52074Aachen, Germany
| | - Hans Kirschner
- Physikalisch-Technische
Bundesanstalt (PTB), 10587Berlin, Germany
| | | | - Mathias Richter
- Physikalisch-Technische
Bundesanstalt (PTB), 10587Berlin, Germany
| | - François
C. Bocquet
- Peter
Grünberg Institute (PGI-3), Forschungszentrum
Jülich, 52425Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals
of Future Information Technology, 52425Jülich, Germany
| | - Serguei Soubatch
- Peter
Grünberg Institute (PGI-3), Forschungszentrum
Jülich, 52425Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals
of Future Information Technology, 52425Jülich, Germany
| | - Georg Koller
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Frank Stefan Tautz
- Peter
Grünberg Institute (PGI-3), Forschungszentrum
Jülich, 52425Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals
of Future Information Technology, 52425Jülich, Germany
- Experimentalphysik
IV A, RWTH Aachen University, 52074Aachen, Germany
| | - Martin Sterrer
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Peter Puschnig
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Michael G. Ramsey
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
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3
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Hasegawa Y, Matsui F, Kera S. Resonant Photoemission Spectroscopy of Highly-Oriented-Coronene Monolayer using Photoelectron Momentum Microscope. e-J Surf Sci Nanotechnol . [DOI: 10.1380/ejssnt.2022-031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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4
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Sättele MS, Windischbacher A, Greulich K, Egger L, Haags A, Kirschner H, Ovsyannikov R, Giangrisostomi E, Gottwald A, Richter M, Soubatch S, Tautz FS, Ramsey MG, Puschnig P, Koller G, Bettinger HF, Chassé T, Peisert H. Hexacene on Cu(110) and Ag(110): Influence of the Substrate on Molecular Orientation and Interfacial Charge Transfer. J Phys Chem C Nanomater Interfaces 2022; 126:5036-5045. [PMID: 35330758 PMCID: PMC8935373 DOI: 10.1021/acs.jpcc.2c00081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 02/15/2022] [Indexed: 06/14/2023]
Abstract
Hexacene, composed of six linearly fused benzene rings, is an organic semiconductor material with superior electronic properties. The fundamental understanding of the electronic and chemical properties is prerequisite to any possible application in devices. We investigate the orientation and interface properties of highly ordered hexacene monolayers on Ag(110) and Cu(110) with X-ray photoemission spectroscopy (XPS), photoemission orbital tomography (POT), X-ray absorption spectroscopy (XAS), low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and density functional theory (DFT). We find pronounced differences in the structural arrangement of the molecules and the electronic properties at the metal/organic interfaces for the two substrates. While on Cu(110) the molecules adsorb with their long molecular axis parallel to the high symmetry substrate direction, on Ag(110), hexacene adsorbs in an azimuthally slightly rotated geometry with respect to the metal rows of the substrate. In both cases, molecular planes are oriented parallel to the substrate. A pronounced charge transfer from both substrates to different molecular states affects the effective charge of different C atoms of the molecule. Through analysis of experimental and theoretical data, we found out that on Ag(110) the LUMO of the molecule is occupied through charge transfer from the metal, whereas on Cu(110) even the LUMO+1 receives a charge. Interface dipoles are determined to a large extent by the push-back effect, which are also found to differ significantly between 6A/Ag(110) and 6A/Cu(110).
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Affiliation(s)
- Marie S Sättele
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
- Institute of Organic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Andreas Windischbacher
- Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Katharina Greulich
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Larissa Egger
- Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Anja Haags
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
- Experimental Physics IV A, RWTH Aachen University, 52074 Aachen, Germany
| | - Hans Kirschner
- Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin, Germany
| | - Ruslan Ovsyannikov
- Institute for Methods and Instrumentation in Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - Erika Giangrisostomi
- Institute for Methods and Instrumentation in Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - Alexander Gottwald
- Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin, Germany
| | - Mathias Richter
- Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin, Germany
| | - Serguei Soubatch
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - F Stefan Tautz
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
- Experimental Physics IV A, RWTH Aachen University, 52074 Aachen, Germany
| | - Michael G Ramsey
- Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Peter Puschnig
- Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Georg Koller
- Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Holger F Bettinger
- Institute of Organic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Thomas Chassé
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
- Center for Light-Matter Interaction, Sensors & Analytics (LISA+), University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Heiko Peisert
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
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5
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Aihara T, Abd-Rahman SA, Yoshida H. Metal screening effect on energy levels at metal/organic interface: Precise determination of screening energy using photoelectron and inverse-photoelectron spectroscopies. Phys Rev B 2021; 104:085305. [DOI: 10.1103/physrevb.104.085305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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6
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Boné T, Windischbacher A, Sättele MS, Greulich K, Egger L, Jauk T, Lackner F, Bettinger HF, Peisert H, Chassé T, Ramsey MG, Sterrer M, Koller G, Puschnig P. Demonstrating the Impact of the Adsorbate Orientation on the Charge Transfer at Organic-Metal Interfaces. J Phys Chem C Nanomater Interfaces 2021; 125:9129-9137. [PMID: 34055126 PMCID: PMC8154845 DOI: 10.1021/acs.jpcc.1c01306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 04/15/2021] [Indexed: 06/12/2023]
Abstract
Charge-transfer processes at molecule-metal interfaces play a key role in tuning the charge injection properties in organic-based devices and thus, ultimately, the device performance. Here, the metal's work function and the adsorbate's electron affinity are the key factors that govern the electron transfer at the organic/metal interface. In our combined experimental and theoretical work, we demonstrate that the adsorbate's orientation may also be decisive for the charge transfer. By thermal cycloreversion of diheptacene isomers, we manage to produce highly oriented monolayers of the rodlike, electron-acceptor molecule heptacene on a Cu(110) surface with molecules oriented either along or perpendicular to the close-packed metal rows. This is confirmed by scanning tunneling microscopy (STM) images as well as by angle-resolved ultraviolet photoemission spectroscopy (ARUPS). By utilizing photoemission tomography momentum maps, we show that the lowest unoccupied molecular orbital (LUMO) is fully occupied and also, the LUMO + 1 gets significantly filled when heptacene is oriented along the Cu rows. Conversely, for perpendicularly aligned heptacene, the molecular energy levels are shifted significantly toward the Fermi energy, preventing charge transfer to the LUMO + 1. These findings are fully confirmed by our density functional calculations and demonstrate the possibility to tune the charge transfer and level alignment at organic-metal interfaces through the adjustable molecular alignment.
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Affiliation(s)
| | | | - Marie S. Sättele
- Institute
of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
- Institute
of Organic Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Katharina Greulich
- Institute
of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Larissa Egger
- Institute
of Physics, University of Graz, 8010 Graz, Austria
| | - Thomas Jauk
- Institute
of Experimental Physics, Graz University of Technology, 8010 Graz, Austria
| | - Florian Lackner
- Institute
of Experimental Physics, Graz University of Technology, 8010 Graz, Austria
| | - Holger F. Bettinger
- Institute
of Organic Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Heiko Peisert
- Institute
of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Thomas Chassé
- Institute
of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | | | - Martin Sterrer
- Institute
of Physics, University of Graz, 8010 Graz, Austria
| | - Georg Koller
- Institute
of Physics, University of Graz, 8010 Graz, Austria
| | - Peter Puschnig
- Institute
of Physics, University of Graz, 8010 Graz, Austria
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7
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Sättele M, Windischbacher A, Egger L, Haags A, Hurdax P, Kirschner H, Gottwald A, Richter M, Bocquet F, Soubatch S, Tautz FS, Bettinger HF, Peisert H, Chassé T, Ramsey MG, Puschnig P, Koller G. Going beyond Pentacene: Photoemission Tomography of a Heptacene Monolayer on Ag(110). J Phys Chem C Nanomater Interfaces 2021; 125:2918-2925. [PMID: 33603943 PMCID: PMC7883341 DOI: 10.1021/acs.jpcc.0c09062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 01/15/2021] [Indexed: 06/12/2023]
Abstract
Longer acenes such as heptacene are promising candidates for optoelectronic applications but are unstable in their bulk structure as they tend to dimerize. This makes the growth of well-defined monolayers and films problematic. In this article, we report the successful preparation of a highly oriented monolayer of heptacene on Ag(110) by thermal cycloreversion of diheptacenes. In a combined effort of angle-resolved photoemission spectroscopy and density functional theory (DFT) calculations, we characterize the electronic and structural properties of the molecule on the surface in detail. Our investigations allow us to unambiguously confirm the successful fabrication of a highly oriented complete monolayer of heptacene and to describe its electronic structure. By comparing experimental momentum maps of photoemission from frontier orbitals of heptacene and pentacene, we shed light on differences between these two acenes regarding their molecular orientation and energy-level alignment on the metal surfaces.
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Affiliation(s)
- Marie
S. Sättele
- Institute
of Physical and Theoretical Chemistry, University
of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
- Institute
of Organic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Andreas Windischbacher
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz
5, 8010 Graz, Austria
| | - Larissa Egger
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz
5, 8010 Graz, Austria
| | - Anja Haags
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals
of Future Information Technology, 52425 Jülich, Germany
- Experimental
Physics IV A, RWTH Aachen University, 52074 Aachen, Germany
| | - Philipp Hurdax
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz
5, 8010 Graz, Austria
| | - Hans Kirschner
- Physikalisch-Technische
Bundesanstalt, Abbestr.
2-12, 10587 Berlin, Germany
| | - Alexander Gottwald
- Physikalisch-Technische
Bundesanstalt, Abbestr.
2-12, 10587 Berlin, Germany
| | - Mathias Richter
- Physikalisch-Technische
Bundesanstalt, Abbestr.
2-12, 10587 Berlin, Germany
| | - François
C. Bocquet
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals
of Future Information Technology, 52425 Jülich, Germany
| | - Serguei Soubatch
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals
of Future Information Technology, 52425 Jülich, Germany
| | - F. Stefan Tautz
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals
of Future Information Technology, 52425 Jülich, Germany
- Experimental
Physics IV A, RWTH Aachen University, 52074 Aachen, Germany
| | - Holger F. Bettinger
- Institute
of Organic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Heiko Peisert
- Institute
of Physical and Theoretical Chemistry, University
of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Thomas Chassé
- Institute
of Physical and Theoretical Chemistry, University
of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Michael G. Ramsey
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz
5, 8010 Graz, Austria
| | - Peter Puschnig
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz
5, 8010 Graz, Austria
| | - Georg Koller
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz
5, 8010 Graz, Austria
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8
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Wang Q, Chen MT, Franco-Cañellas A, Shen B, Geiger T, F. Bettinger H, Schreiber F, Salzmann I, Gerlach A, Duhm S. Impact of fluorination on interface energetics and growth of pentacene on Ag(111). Beilstein J Nanotechnol 2020; 11:1361-1370. [PMID: 32974114 PMCID: PMC7492695 DOI: 10.3762/bjnano.11.120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 08/19/2020] [Indexed: 05/26/2023]
Abstract
We studied the structural and electronic properties of 2,3,9,10-tetrafluoropentacene (F4PEN) on Ag(111) via X-ray standing waves (XSW), low-energy electron diffraction (LEED) as well as ultraviolet and X-ray photoelectron spectroscopy (UPS and XPS). XSW revealed that the adsorption distances of F4PEN in (sub)monolayers on Ag(111) were 3.00 Å for carbon atoms and 3.05 Å for fluorine atoms. The F4PEN monolayer was essentially lying on Ag(111), and multilayers adopted π-stacking. Our study shed light not only on the F4PEN-Ag(111) interface but also on the fundamental adsorption behavior of fluorinated pentacene derivatives on metals in the context of interface energetics and growth mode.
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Affiliation(s)
- Qi Wang
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Meng-Ting Chen
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123, People’s Republic of China
| | - Antoni Franco-Cañellas
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Bin Shen
- Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Thomas Geiger
- Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Holger F. Bettinger
- Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Frank Schreiber
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Ingo Salzmann
- Department of Physics, Department of Chemistry & Biochemistry, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec H4B 1R6, Canada
| | - Alexander Gerlach
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Steffen Duhm
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123, People’s Republic of China
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9
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Natali M, Prosa M, Longo A, Brucale M, Mercuri F, Buonomo M, Lago N, Benvenuti E, Prescimone F, Bettini C, Cester A, Melucci M, Muccini M, Toffanin S. On the Nature of Charge-Injecting Contacts in Organic Field-Effect Transistors. ACS Appl Mater Interfaces 2020; 12:30616-30626. [PMID: 32519550 DOI: 10.1021/acsami.0c05106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Organic field-effect transistors (OFETs) are key enabling devices for plastic electronics technology, which has a potentially disruptive impact on a variety of application fields, such as health, safety, and communication. Despite the tremendous advancements in understanding the OFET working mechanisms and device performance, further insights into the complex correlation between the nature of the charge-injecting contacts and the electrical characteristics of devices are still necessary. Here, an in-depth study of the metal-organic interfaces that provides a direct correlation to the performance of OFET devices is reported. The combination of synchrotron X-ray spectroscopy, atomic force microscopy, electron microscopy, and theoretical simulations on two selected electron transport organic semiconductors with tailored chemical structures allows us to gain insights into the nature of the injecting contacts. This multiple analysis repeated at the different stages of contact formation provides a clear picture on the synergy between organic/metal interactions, interfacial morphology, and structural organization of the electrode. The simultaneous synchrotron X-ray experiments and electrical measurements of OFETs in operando uncovers how the nature of the charge-injecting contacts has a direct impact on the injection potential of OFETs.
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Affiliation(s)
- Marco Natali
- Consiglio Nazionale delle Ricerche (CNR)-Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), Via P. Gobetti 101, 40129 Bologna, Italy
| | - Mario Prosa
- Consiglio Nazionale delle Ricerche (CNR)-Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), Via P. Gobetti 101, 40129 Bologna, Italy
| | - Alessandro Longo
- Consiglio Nazionale delle Ricerche (CNR)-Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), Via P. Gobetti 101, 40129 Bologna, Italy
- European Synchrotron Radiation Facility, The European Synchrotron, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Marco Brucale
- Consiglio Nazionale delle Ricerche (CNR)-Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), Via P. Gobetti 101, 40129 Bologna, Italy
| | - Francesco Mercuri
- Consiglio Nazionale delle Ricerche (CNR)-Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), Via P. Gobetti 101, 40129 Bologna, Italy
| | - Marco Buonomo
- Department of Information Engineering, University of Padova, 35131 Padova, Italy
| | - Nicolò Lago
- Department of Information Engineering, University of Padova, 35131 Padova, Italy
| | - Emilia Benvenuti
- Consiglio Nazionale delle Ricerche (CNR)-Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), Via P. Gobetti 101, 40129 Bologna, Italy
| | - Federico Prescimone
- Consiglio Nazionale delle Ricerche (CNR)-Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), Via P. Gobetti 101, 40129 Bologna, Italy
| | - Cristian Bettini
- Consiglio Nazionale delle Ricerche (CNR)-Istituto per la Sintesi Organica e la Fotoreattività (ISOF), Via P. Gobetti 101, 40129 Bologna, Italy
| | - Andrea Cester
- Department of Information Engineering, University of Padova, 35131 Padova, Italy
| | - Manuela Melucci
- Consiglio Nazionale delle Ricerche (CNR)-Istituto per la Sintesi Organica e la Fotoreattività (ISOF), Via P. Gobetti 101, 40129 Bologna, Italy
| | - Michele Muccini
- Consiglio Nazionale delle Ricerche (CNR)-Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), Via P. Gobetti 101, 40129 Bologna, Italy
| | - Stefano Toffanin
- Consiglio Nazionale delle Ricerche (CNR)-Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), Via P. Gobetti 101, 40129 Bologna, Italy
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10
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Franco-Cañellas A, Duhm S, Gerlach A, Schreiber F. Binding and electronic level alignment of π-conjugated systems on metals. Rep Prog Phys 2020; 83:066501. [PMID: 32101802 DOI: 10.1088/1361-6633/ab7a42] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
We review the binding and energy level alignment of π-conjugated systems on metals, a field which during the last two decades has seen tremendous progress both in terms of experimental characterization as well as in the depth of theoretical understanding. Precise measurements of vertical adsorption distances and the electronic structure together with ab initio calculations have shown that most of the molecular systems have to be considered as intermediate cases between weak physisorption and strong chemisorption. In this regime, the subtle interplay of different effects such as covalent bonding, charge transfer, electrostatic and van der Waals interactions yields a complex situation with different adsorption mechanisms. In order to establish a better understanding of the binding and the electronic level alignment of π-conjugated molecules on metals, we provide an up-to-date overview of the literature, explain the fundamental concepts as well as the experimental techniques and discuss typical case studies. Thereby, we relate the geometric with the electronic structure in a consistent picture and cover the entire range from weak to strong coupling.
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Affiliation(s)
- Antoni Franco-Cañellas
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
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11
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Abstract
In the rapidly developing electronics industry, it has become increasingly necessary to explore materials that are cheap, flexible and versatile which have led to significant research efforts towards organic molecular thin films. Organic molecules are unique compared to their inorganic atomic counterparts as their properties can be tuned drastically through chemical functionalization, offering versatility, though their extended shape and weak intermolecular interactions bring significant challenges to the control of both the growth and the electronic structures of molecular thin films. In this paper, we will review the self-assembly process and how to establish long-range ordered organic molecular thin films. We will also discuss how the electronic structures of thin films are impacted by the molecule's local electrostatic environment and its interaction with the substrate, within the context of controlling interfacial energy level alignment between organic semiconductors and electrodes in electronic devices.
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Affiliation(s)
- Andrew Tan
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, United States of America
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12
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Yang X, Egger L, Fuchsberger J, Unzog M, Lüftner D, Hajek F, Hurdax P, Jugovac M, Zamborlini G, Feyer V, Koller G, Puschnig P, Tautz FS, Ramsey MG, Soubatch S. Coexisting Charge States in a Unary Organic Monolayer Film on a Metal. J Phys Chem Lett 2019; 10:6438-6445. [PMID: 31573816 DOI: 10.1021/acs.jpclett.9b02231] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The electronic and geometric structures of tetracene films on Ag(110) and Cu(110) have been studied with photoemission tomography and compared to that of pentacene. Despite similar energy level alignment of the two oligoacenes on these surfaces revealed by conventional ultraviolet photoelectron spectroscopy, the momentum-space resolved photoemission tomography reveals a significant difference in both structural and electronic properties of tetracene and pentacene films. Particularly, the saturated monolayer of tetracene on Ag(110) is found to consist of two molecular species that, despite having the same orientation, are electronically very different-while one molecule remains neutral, another is charged because of electron donation from the substrate.
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Affiliation(s)
- Xiaosheng Yang
- Peter Grünberg Institut (PGI-3) , Forschungszentrum Jülich , 52425 Jülich , Germany
- Jülich Aachen Research Alliance (JARA)-Fundamentals of Future Information Technology , 52425 Jülich , Germany
- Experimental Physics IV A , RWTH Aachen University , 52074 Aachen , Germany
| | - Larissa Egger
- Institute of Physics , University of Graz , NAWI Graz, 8010 Graz , Austria
| | - Jana Fuchsberger
- Institute of Physics , University of Graz , NAWI Graz, 8010 Graz , Austria
| | - Martin Unzog
- Institute of Physics , University of Graz , NAWI Graz, 8010 Graz , Austria
| | - Daniel Lüftner
- Institute of Physics , University of Graz , NAWI Graz, 8010 Graz , Austria
| | - Felix Hajek
- Institute of Physics , University of Graz , NAWI Graz, 8010 Graz , Austria
| | - Philipp Hurdax
- Institute of Physics , University of Graz , NAWI Graz, 8010 Graz , Austria
| | - Matteo Jugovac
- Peter Grünberg Institut (PGI-6) , Forschungszentrum Jülich , 52425 Jülich , Germany
| | - Giovanni Zamborlini
- Peter Grünberg Institut (PGI-6) , Forschungszentrum Jülich , 52425 Jülich , Germany
| | - Vitaliy Feyer
- Peter Grünberg Institut (PGI-6) , Forschungszentrum Jülich , 52425 Jülich , Germany
| | - Georg Koller
- Institute of Physics , University of Graz , NAWI Graz, 8010 Graz , Austria
| | - Peter Puschnig
- Institute of Physics , University of Graz , NAWI Graz, 8010 Graz , Austria
| | - F Stefan Tautz
- Peter Grünberg Institut (PGI-3) , Forschungszentrum Jülich , 52425 Jülich , Germany
- Jülich Aachen Research Alliance (JARA)-Fundamentals of Future Information Technology , 52425 Jülich , Germany
- Experimental Physics IV A , RWTH Aachen University , 52074 Aachen , Germany
| | - Michael G Ramsey
- Institute of Physics , University of Graz , NAWI Graz, 8010 Graz , Austria
| | - Serguei Soubatch
- Peter Grünberg Institut (PGI-3) , Forschungszentrum Jülich , 52425 Jülich , Germany
- Jülich Aachen Research Alliance (JARA)-Fundamentals of Future Information Technology , 52425 Jülich , Germany
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13
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Wagner C, Green MFB, Maiworm M, Leinen P, Esat T, Ferri N, Friedrich N, Findeisen R, Tkatchenko A, Temirov R, Tautz FS. Quantitative imaging of electric surface potentials with single-atom sensitivity. Nat Mater 2019; 18:853-859. [PMID: 31182779 PMCID: PMC6656579 DOI: 10.1038/s41563-019-0382-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 04/18/2019] [Indexed: 05/09/2023]
Abstract
Because materials consist of positive nuclei and negative electrons, electric potentials are omnipresent at the atomic scale. However, due to the long range of the Coulomb interaction, large-scale structures completely outshine small ones. This makes the isolation and quantification of the electric potentials that originate from nanoscale objects such as atoms or molecules very challenging. Here we report a non-contact scanning probe technique that addresses this challenge. It exploits a quantum dot sensor and the joint electrostatic screening by tip and surface, thus enabling quantitative surface potential imaging across all relevant length scales down to single atoms. We apply the technique to the characterization of a nanostructured surface, thereby extracting workfunction changes and dipole moments for important reference systems. This authenticates the method as a versatile tool to study the building blocks of materials and devices down to the atomic scale.
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Affiliation(s)
- Christian Wagner
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Jülich, Germany.
- Jülich Aachen Research Alliance (JARA)-Fundamentals of Future Information Technology, Jülich, Germany.
| | - Matthew F B Green
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Jülich, Germany
- Jülich Aachen Research Alliance (JARA)-Fundamentals of Future Information Technology, Jülich, Germany
- Experimentalphysik IV A, RWTH Aachen University, Aachen, Germany
| | - Michael Maiworm
- Otto-von-Guericke-Universität Magdeburg, Laboratory for Systems Theory and Automatic Control, Magdeburg, Germany
| | - Philipp Leinen
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Jülich, Germany
- Jülich Aachen Research Alliance (JARA)-Fundamentals of Future Information Technology, Jülich, Germany
- Experimentalphysik IV A, RWTH Aachen University, Aachen, Germany
| | - Taner Esat
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Jülich, Germany
- Jülich Aachen Research Alliance (JARA)-Fundamentals of Future Information Technology, Jülich, Germany
- Experimentalphysik IV A, RWTH Aachen University, Aachen, Germany
| | - Nicola Ferri
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
| | - Niklas Friedrich
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Jülich, Germany
- Jülich Aachen Research Alliance (JARA)-Fundamentals of Future Information Technology, Jülich, Germany
- Experimentalphysik IV A, RWTH Aachen University, Aachen, Germany
| | - Rolf Findeisen
- Otto-von-Guericke-Universität Magdeburg, Laboratory for Systems Theory and Automatic Control, Magdeburg, Germany
| | - Alexandre Tkatchenko
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
- Physics and Materials Science Research Unit, University of Luxembourg, Luxembourg, Luxembourg
| | - Ruslan Temirov
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Jülich, Germany
- Jülich Aachen Research Alliance (JARA)-Fundamentals of Future Information Technology, Jülich, Germany
- II. Physikalisches Institut, Universität zu Köln, Köln, Germany
| | - F Stefan Tautz
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Jülich, Germany
- Jülich Aachen Research Alliance (JARA)-Fundamentals of Future Information Technology, Jülich, Germany
- Experimentalphysik IV A, RWTH Aachen University, Aachen, Germany
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14
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Chen MT, Hofmann OT, Gerlach A, Bröker B, Bürker C, Niederhausen J, Hosokai T, Zegenhagen J, Vollmer A, Rieger R, Müllen K, Schreiber F, Salzmann I, Koch N, Zojer E, Duhm S. Energy-level alignment at strongly coupled organic-metal interfaces. J Phys Condens Matter 2019; 31:194002. [PMID: 30673641 DOI: 10.1088/1361-648x/ab0171] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Energy-level alignment at organic-metal interfaces plays a crucial role for the performance of organic electronic devices. However, reliable models to predict energetics at strongly coupled interfaces are still lacking. We elucidate contact formation of 1,2,5,6,9,10-coronenehexone (COHON) to the (1 1 1)-surfaces of coinage metals by means of ultraviolet photoelectron spectroscopy, x-ray photoelectron spectroscopy, the x-ray standing wave technique, and density functional theory calculations. While for low COHON thicknesses, the work-functions of the systems vary considerably, for thicker organic films Fermi-level pinning leads to identical work functions of 5.2 eV for all COHON-covered metals irrespective of the pristine substrate work function and the interfacial interaction strength.
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Affiliation(s)
- Meng-Ting Chen
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, 199 Ren-Ai Road, Suzhou 215123, People's Republic of China
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15
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Stadtmüller B, Grad L, Seidel J, Haag F, Haag N, Cinchetti M, Aeschlimann M. Modification of Pb quantum well states by the adsorption of organic molecules. J Phys Condens Matter 2019; 31:134005. [PMID: 30625428 DOI: 10.1088/1361-648x/aafcf5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The successful implementation of nanoscale materials in next generation optoelectronic devices crucially depends on our ability to functionalize and design low dimensional materials according to the desired field of application. Recently, organic adsorbates have revealed an enormous potential to alter the occupied surface band structure of tunable materials by the formation of tailored molecule-surface bonds. Here, we extend this concept of adsorption-induced surface band structure engineering to the unoccupied part of the surface band structure. This is achieved by our comprehensive investigation of the unoccupied band structure of a lead (Pb) monolayer film on the Ag(1 1 1) surface prior and after the adsorption of one monolayer of the aromatic molecule 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA). Using two-photon momentum microscopy, we show that the unoccupied states of the Pb/Ag(1 1 1) bilayer system are dominated by a parabolic quantum well state (QWS) in the center of the surface Brillouin zone with Pb p[Formula: see text] orbital character and a side band with almost linear dispersion showing Pb p[Formula: see text] orbital character. After the adsorption of PTCDA, the Pb side band remains completely unaffected while the signal of the Pb QWS is fully suppressed. This adsorption induced change in the unoccupied Pb band structure coincides with an interfacial charge transfer from the Pb layer into the PTCDA molecule. We propose that this charge transfer and the correspondingly vertical (partially chemical) interaction across the PTCDA/Pb interface suppresses the existence of the QWS in the Pb layer. Our results hence unveil a new possibility to orbital selectively tune and control the entire surface band structure of low dimensional systems by the adsorption of organic molecules.
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Affiliation(s)
- Benjamin Stadtmüller
- Department of Physics and OPTIMAS Research Center, TU Kaiserslautern, Erwin-Schrödinger-Strasse 46, 67663 Kaiserslautern, Germany. Graduate School of Excellence Materials Science in Mainz, Erwin-Schrödinger-Strasse 46, 67663 Kaiserslautern, Germany
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16
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Felter J, Wolters J, Bocquet FC, Tautz FS, Kumpf C. Momentum microscopy on the micrometer scale: photoemission micro-tomography applied to single molecular domains. J Phys Condens Matter 2019; 31:114003. [PMID: 30616228 DOI: 10.1088/1361-648x/aafc45] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Photoemission tomography (PT) is a newly developed method for analyzing angular resolved photoemission data. In combination with momentum microscopy it allows for a comprehensive investigation of the electronic structure of (in particular) metal-organic interfaces as they occur in organic electronic devices. The most interesting aspect in this context is the band alignment, the control of which is indispensable for designing devices. Since PT is based on characteristic photoemission patterns that are used as fingerprints, the method works well as long as these patterns are uniquely representing the specific molecular orbital they are originating from. But this limiting factor is often not fulfilled for systems exhibiting many differently oriented molecules, as they may occur on highly symmetric substrate surfaces. Here we show that this limitation can be lifted by recording the photoemission data in a momentum microscope and limiting the probed surface area to only a few micrometers squared, since this corresponds to a typical domain size for many systems. We demonstrate this by recording data from a single domain of the archetypal adsorbate system 1,4,5,8-naphthalenetetracarboxylic dianhydride on Cu(0 0 1). This proof of principle experiment paves the way for establishing the photoemission [Formula: see text]-tomography method as an ideal tool for investigating the electronic structure of metal-organic interfaces with so far unraveled clarity and unambiguity.
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Affiliation(s)
- Janina Felter
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany. Jülich Aachen Research Alliance (JARA)-Fundamentals of Future Information Technology, 52425 Jülich, Germany
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17
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Zaitsev NL, Jakob P, Tonner R. Structure and vibrational properties of the PTCDA/Ag(1 1 1) interface: bilayer versus monolayer. J Phys Condens Matter 2018; 30:354001. [PMID: 30039803 DOI: 10.1088/1361-648x/aad576] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The structural and vibrational properties of metal-organic interfaces have been examined by means of infrared (IR) absorption spectroscopy and density functional theory (DFT) with an approach accounting for long-range dispersive interactions. We focus on a comparative study of the PTCDA monolayer and bilayer on Ag(1 1 1). The equilibrium geometry at the molecule-metal interface and the IR spectrum of the chemisorbed monolayer of PTCDA on Ag(1 1 1) are well described by the computations. In the bilayer structure, the presence of a physisorbed adlayer on top of PTCDA/Ag(1 1 1) presents a challenge for DFT. As previously described for other systems, the polarization of the substrate is not captured correctly and results in too low energies of frontier molecular orbitals. This results in an apparent contribution from the vibrations of second-layer PTCDA to the IR spectrum due to interfacial dynamical charge transfer processes. After removing these peaks with artificially strong intensity, calculated and experimental data show good agreement and the IR spectrum can be described as the sum of the spectra of the PTCDA/Ag(1 1 1) contact layer and a physisorbed PTCDA monolayer on top.
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Affiliation(s)
- N L Zaitsev
- Laboratory of Theoretical Physics, Institute of Molecule and Crystal Physics-Subdivision of the Ufa Federal Research Center of the Russian Academy of Sciences, 450075, Ufa, Russia. Laboratory of Nanostructured Surfaces and Coating, Tomsk State University, 634050, Tomsk, Russia
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18
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Merino-Díez N, Lobo-Checa J, Nita P, Garcia-Lekue A, Basagni A, Vasseur G, Tiso F, Sedona F, Das PK, Fujii J, Vobornik I, Sambi M, Pascual JI, Ortega JE, de Oteyza DG. Switching from Reactant to Substrate Engineering in the Selective Synthesis of Graphene Nanoribbons. J Phys Chem Lett 2018; 9:2510-2517. [PMID: 29688007 DOI: 10.1021/acs.jpclett.8b00796] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The challenge of synthesizing graphene nanoribbons (GNRs) with atomic precision is currently being pursued along a one-way road, based on the synthesis of adequate molecular precursors that react in predefined ways through self-assembly processes. The synthetic options for GNR generation would multiply by adding a new direction to this readily successful approach, especially if both of them can be combined. We show here how GNR synthesis can be guided by an adequately nanotemplated substrate instead of by the traditionally designed reactants. The structural atomic precision, unachievable to date through top-down methods, is preserved by the self-assembly process. This new strategy's proof-of-concept compares experiments using 4,4''-dibromo-para-terphenyl as a molecular precursor on flat Au(111) and stepped Au(322) substrates. As opposed to the former, the periodic steps of the latter drive the selective synthesis of 6 atom-wide armchair GNRs, whose electronic properties have been further characterized in detail by scanning tunneling spectroscopy, angle resolved photoemission, and density functional theory calculations.
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Affiliation(s)
- Néstor Merino-Díez
- Donostia International Physics Center (DIPC) , 20018 San Sebastián , Spain
- Centro de Física de Materiales (CSIC-UPV/EHU) - MPC , 20018 San Sebastián , Spain
- CIC nanoGUNE , Nanoscience Cooperative Research Center , 20018 San Sebastián-Donostia , Spain
| | - Jorge Lobo-Checa
- Instituto de Ciencia de Materiales de Aragón (ICMA) , CSIC-Universidad de Zaragoza , 50009 Zaragoza , Spain
- Departamento de Física de la Materia Condensada , Universidad de Zaragoza , 50009 Zaragoza , Spain
| | - Pawel Nita
- Donostia International Physics Center (DIPC) , 20018 San Sebastián , Spain
- Centro de Física de Materiales (CSIC-UPV/EHU) - MPC , 20018 San Sebastián , Spain
| | - Aran Garcia-Lekue
- Donostia International Physics Center (DIPC) , 20018 San Sebastián , Spain
- Ikerbasque, Basque Foundation for Science, 48011 Bilbao , Spain
| | - Andrea Basagni
- Dipartimento di Scienze Chimiche , Università Degli Studi Di Padova , 35131 Padova , Italy
| | - Guillaume Vasseur
- Donostia International Physics Center (DIPC) , 20018 San Sebastián , Spain
- Centro de Física de Materiales (CSIC-UPV/EHU) - MPC , 20018 San Sebastián , Spain
| | - Federica Tiso
- Dipartimento di Scienze Chimiche , Università Degli Studi Di Padova , 35131 Padova , Italy
| | - Francesco Sedona
- Dipartimento di Scienze Chimiche , Università Degli Studi Di Padova , 35131 Padova , Italy
| | - Pranab K Das
- Istituto Officina dei Materiali (IOM)-CNR , Laboratorio TASC , 34149 Trieste , Italy
- International Centre for Theoretical Physics , 34100 Trieste , Italy
| | - Jun Fujii
- Istituto Officina dei Materiali (IOM)-CNR , Laboratorio TASC , 34149 Trieste , Italy
| | - Ivana Vobornik
- Istituto Officina dei Materiali (IOM)-CNR , Laboratorio TASC , 34149 Trieste , Italy
| | - Mauro Sambi
- Dipartimento di Scienze Chimiche , Università Degli Studi Di Padova , 35131 Padova , Italy
- Consorzio INSTM , Unità di Ricerca di Padova , 35131 Padova , Italy
| | - José Ignacio Pascual
- CIC nanoGUNE , Nanoscience Cooperative Research Center , 20018 San Sebastián-Donostia , Spain
- Ikerbasque, Basque Foundation for Science, 48011 Bilbao , Spain
| | - J Enrique Ortega
- Donostia International Physics Center (DIPC) , 20018 San Sebastián , Spain
- Centro de Física de Materiales (CSIC-UPV/EHU) - MPC , 20018 San Sebastián , Spain
- Departamento de Física Aplicada I , Universidad del Pais Vasco , 20018 San Sebastián , Spain
| | - Dimas G de Oteyza
- Donostia International Physics Center (DIPC) , 20018 San Sebastián , Spain
- Centro de Física de Materiales (CSIC-UPV/EHU) - MPC , 20018 San Sebastián , Spain
- Ikerbasque, Basque Foundation for Science, 48011 Bilbao , Spain
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19
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Sanz-Matías A, Ivasenko O, Fang Y, De Feyter S, Tahara K, Tobe Y, Harvey JN. Computational insight into the origin of unexpected contrast in chiral markers as revealed by STM. Nanoscale 2018; 10:1680-1694. [PMID: 29265120 DOI: 10.1039/c7nr07395j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Internal substituents can serve the double purpose of generating stereogenic centers and (potentially) being identifiable with Scanning Tunneling Microscopy (STM) in 2D self-assembled molecular layers. We investigate computationally the origin of stark contrast variations in STM images of chirally substituted self-assembled organic films. STM images of alkyl derivatives with secondary -CH3 and -OH groups have been simulated. Density functional theory calculations reveal bias-dependent contrast reversals in the substituent regions: a lack of local density of states in the relevant energy regime results in 'dark spots' in the simulated STM images, which turn bright upon increasing the bias voltage.
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Affiliation(s)
- Ana Sanz-Matías
- Quantum Chemistry and Physical Chemistry, Department of Chemistry, KU Leuven, BE-3001 Leuven, Belgium.
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20
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Tsuneda T, Singh RK, Chattaraj PK. Diagrams for comprehensive molecular orbital-based chemical reaction analyses: reactive orbital energy diagrams. Phys Chem Chem Phys 2018; 20:14211-14222. [DOI: 10.1039/c8cp00461g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reactive orbital energy diagrams resting on the reactive orbital energy theory correct conventional frontier orbital diagrams and make it possible to perform comprehensive orbital-based analyses of reactions.
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Affiliation(s)
- Takao Tsuneda
- Fuel Cell Nanomaterials Center
- University of Yamanashi
- Kofu 400-0021
- Japan
| | - Raman Kumar Singh
- Department of Chemistry
- Jagdam College
- Jai Prakash University
- Chapra
- Bihar-841301
| | - Pratim Kumar Chattaraj
- Department of Chemistry and Centre for Theoretical Studies
- Indian Institute of Technology Kharagpur
- India
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21
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Yang X, Krieger I, Lüftner D, Weiß S, Heepenstrick T, Hollerer M, Hurdax P, Koller G, Sokolowski M, Puschnig P, Ramsey MG, Tautz FS, Soubatch S. On the decoupling of molecules at metal surfaces. Chem Commun (Camb) 2018; 54:9039-9042. [DOI: 10.1039/c8cc03334j] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electronic surface hardening induced by oxygen atoms deposited on Cu(100) results in a true electronic and physical decoupling of adsorbed organic molecules.
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22
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Hofmann OT, Glowatzki H, Bürker C, Rangger GM, Bröker B, Niederhausen J, Hosokai T, Salzmann I, Blum RP, Rieger R, Vollmer A, Rajput P, Gerlach A, Müllen K, Schreiber F, Zojer E, Koch N, Duhm S. Orientation-Dependent Work-Function Modification Using Substituted Pyrene-Based Acceptors. J Phys Chem C Nanomater Interfaces 2017; 121:24657-24668. [PMID: 29152034 PMCID: PMC5682610 DOI: 10.1021/acs.jpcc.7b08451] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 10/10/2017] [Indexed: 05/17/2023]
Abstract
The adsorption of molecular acceptors is a viable method for tuning the work function of metal electrodes. This, in turn, enables adjusting charge injection barriers between the electrode and organic semiconductors. Here, we demonstrate the potential of pyrene-tetraone (PyT) and its derivatives dibromopyrene-tetraone (Br-PyT) and dinitropyrene-tetraone (NO2-PyT) for modifying the electronic properties of Au(111) and Ag(111) surfaces. The systems are investigated by complementary theoretical and experimental approaches, including photoelectron spectroscopy, the X-ray standing wave technique, and density functional theory simulations. For some of the investigated interfaces the trends expected for Fermi-level pinning are observed, i.e., an increase of the metal work function along with increasing molecular electron affinity and the same work function for Au and Ag with monolayer acceptor coverage. Substantial deviations are, however, found for Br-PyT/Ag(111) and NO2-PyT/Ag(111), where in the latter case an adsorption-induced work function increase of as much as 1.6 eV is observed. This behavior is explained as arising from a face-on to edge-on reorientation of molecules in the monolayer. Our calculations show that for an edge-on orientation much larger work-function changes can be expected despite the prevalence of Fermi-level pinning. This is primarily ascribed to a change of the electron affinity of the adsorbate layer that results from a change of the molecular orientation. This work provides a comprehensive understanding of how changing the molecular electron affinity as well as the adsorbate structure impacts the electronic properties of electrodes.
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Affiliation(s)
- O. T. Hofmann
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
- E-mail:
| | - H. Glowatzki
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - C. Bürker
- Institut
für Angewandte Physik, Universität
Tübingen, Auf
der Morgenstelle 10, Tübingen 72076, Germany
| | - G. M. Rangger
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - B. Bröker
- Institut
für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Newtonstraße 15, 12389 Berlin, Germany
| | - J. Niederhausen
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - T. Hosokai
- National
Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - I. Salzmann
- Institut
für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Newtonstraße 15, 12389 Berlin, Germany
- The
Institute of Solid State Physics, The University
of Tokyo, Kashiwanoha
5-1-5, Kashiwa, Chiba 277-8581, Japan
| | - R.-P. Blum
- Institut
für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Newtonstraße 15, 12389 Berlin, Germany
| | - R. Rieger
- Max Planck
Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
| | - A. Vollmer
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - P. Rajput
- Atomic
& Molecular Physics Division, Bhabha
Atomic Research Centre, Trombay, Mumbai 400085, India
| | - A. Gerlach
- Institut
für Angewandte Physik, Universität
Tübingen, Auf
der Morgenstelle 10, Tübingen 72076, Germany
| | - K. Müllen
- Max Planck
Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
- Institute
of Physical Chemistry, Johannes Gutenberg
University Mainz, Duesbergweg
10-14, Mainz, Germany
| | - F. Schreiber
- Institut
für Angewandte Physik, Universität
Tübingen, Auf
der Morgenstelle 10, Tübingen 72076, Germany
| | - E. Zojer
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - N. Koch
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin, Germany
- Institut
für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Newtonstraße 15, 12389 Berlin, Germany
- Jiangsu
Key Laboratory for Carbon-Based Functional Materials & Devices
and Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, 199 Ren-Ai Road, Suzhou 215123, P.R. China
| | - S. Duhm
- Jiangsu
Key Laboratory for Carbon-Based Functional Materials & Devices
and Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, 199 Ren-Ai Road, Suzhou 215123, P.R. China
- E-mail:
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23
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Vaida ME, Bernhardt TM. Tuning the ultrafast photodissociation dynamics of CH 3 Br on ultrathin MgO films by reducing the layer thickness to the 2D limit. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.09.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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24
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Zamborlini G, Lüftner D, Feng Z, Kollmann B, Puschnig P, Dri C, Panighel M, Di Santo G, Goldoni A, Comelli G, Jugovac M, Feyer V, Schneider CM. Multi-orbital charge transfer at highly oriented organic/metal interfaces. Nat Commun 2017; 8:335. [PMID: 28839127 DOI: 10.1038/s41467-017-00402-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 06/22/2017] [Indexed: 11/09/2022] Open
Abstract
The molecule-substrate interaction plays a key role in charge injection organic-based devices. Charge transfer at molecule-metal interfaces strongly affects the overall physical and magnetic properties of the system, and ultimately the device performance. Here, we report theoretical and experimental evidence of a pronounced charge transfer involving nickel tetraphenyl porphyrin molecules adsorbed on Cu(100). The exceptional charge transfer leads to filling of the higher unoccupied orbitals up to LUMO+3. As a consequence of this strong interaction with the substrate, the porphyrin's macrocycle sits very close to the surface, forcing the phenyl ligands to bend upwards. Due to this adsorption configuration, scanning tunneling microscopy cannot reliably probe the states related to the macrocycle. We demonstrate that photoemission tomography can instead access the Ni-TPP macrocycle electronic states and determine the reordering and filling of the LUMOs upon adsorption, thereby confirming the remarkable charge transfer predicted by density functional theory calculations.Charge transfer at molecule-metal interfaces affects the overall physical and magnetic properties of organic-based devices, and ultimately their performance. Here, the authors report evidence of a pronounced charge transfer involving nickel tetraphenyl porphyrin molecules adsorbed on copper.
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25
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Hollerer M, Lüftner D, Hurdax P, Ules T, Soubatch S, Tautz FS, Koller G, Puschnig P, Sterrer M, Ramsey MG. Charge Transfer and Orbital Level Alignment at Inorganic/Organic Interfaces: The Role of Dielectric Interlayers. ACS Nano 2017; 11:6252-6260. [PMID: 28541656 PMCID: PMC5492217 DOI: 10.1021/acsnano.7b02449] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Accepted: 05/25/2017] [Indexed: 05/17/2023]
Abstract
It is becoming accepted that ultrathin dielectric layers on metals are not merely passive decoupling layers, but can actively influence orbital energy level alignment and charge transfer at interfaces. As such, they can be important in applications ranging from catalysis to organic electronics. However, the details at the molecular level are still under debate. In this study, we present a comprehensive analysis of the phenomenon of charge transfer promoted by a dielectric interlayer with a comparative study of pentacene adsorbed on Ag(001) with and without an ultrathin MgO interlayer. Using scanning tunneling microscopy and photoemission tomography supported by density functional theory, we are able to identify the orbitals involved and quantify the degree of charge transfer in both cases. Fractional charge transfer occurs for pentacene adsorbed on Ag(001), while the presence of the ultrathin MgO interlayer promotes integer charge transfer with the lowest unoccupied molecular orbital transforming into a singly occupied and singly unoccupied state separated by a large gap around the Fermi energy. Our experimental approach allows a direct access to the individual factors governing the energy level alignment and charge-transfer processes for molecular adsorbates on inorganic substrates.
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Affiliation(s)
- Michael Hollerer
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Daniel Lüftner
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Philipp Hurdax
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Thomas Ules
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Serguei Soubatch
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Fundamentals
of Future Information Technology, Jülich
Aachen Research Alliance (JARA), 52425 Jülich, Germany
| | - Frank Stefan Tautz
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Fundamentals
of Future Information Technology, Jülich
Aachen Research Alliance (JARA), 52425 Jülich, Germany
| | - Georg Koller
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Peter Puschnig
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Martin Sterrer
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
- E-mail:
| | - Michael G. Ramsey
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
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26
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Abstract
The miniaturization trend in the semiconductor industry has led to the understanding that interfacial properties are crucial for device behaviour. Spintronics has not been alien to this trend, and phenomena such as preferential spin tunnelling, the spin-to-charge conversion due to the Rashba-Edelstein effect and the spin-momentum locking at the surface of topological insulators have arisen mainly from emergent interfacial properties, rather than the bulk of the constituent materials. In this Perspective we explore inorganic/molecular interfaces by looking closely at both sides of the interface. We describe recent developments and discuss the interface as an ideal platform for creating new spin effects. Finally, we outline possible technologies that can be generated thanks to the unique active tunability of molecular spinterfaces.
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Affiliation(s)
- Mirko Cinchetti
- Experimentelle Physik VI, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - V Alek Dediu
- Istituto per lo Studio dei Materiali Nanostrutturati CNRISMN, 40129 Bologna, Italy
| | - Luis E Hueso
- CIC nanoGUNE, 20018 San Sebastian, Spain
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
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27
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Liu ZF, Egger DA, Refaely-Abramson S, Kronik L, Neaton JB. Energy level alignment at molecule-metal interfaces from an optimally tuned range-separated hybrid functional. J Chem Phys 2017. [DOI: 10.1063/1.4975321] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Zhen-Fei Liu
- Molecular Foundry and Materials Sciences Division,
Lawrence Berkeley National Laboratory, Berkeley, California
94720, USA
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - David A. Egger
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
| | - Sivan Refaely-Abramson
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
| | - Leeor Kronik
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
| | - Jeffrey B. Neaton
- Molecular Foundry and Materials Sciences Division,
Lawrence Berkeley National Laboratory, Berkeley, California
94720, USA
- Department of Physics, University of California, Berkeley, California 94720, USA
- Kavli Energy Nanosciences Institute at Berkeley, Berkeley, California 94720, USA
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28
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Affiliation(s)
- Xavier Bouju
- CEMES-CNRS, 29 Rue J. Marvig, 31055 Toulouse, France
| | | | - Grégory Franc
- CEMES-CNRS, 29 Rue J. Marvig, 31055 Toulouse, France
| | - Adeline Pujol
- Université de Toulouse, UPS, CNRS, CEMES, 118 route de Narbonne, 31062 Toulouse, France
| | - André Gourdon
- CEMES-CNRS, 29 Rue J. Marvig, 31055 Toulouse, France
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29
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Puschnig P, Boese AD, Willenbockel M, Meyer M, Lüftner D, Reinisch EM, Ules T, Koller G, Soubatch S, Ramsey MG, Tautz FS. Energy Ordering of Molecular Orbitals. J Phys Chem Lett 2017; 8:208-213. [PMID: 27935313 PMCID: PMC5220489 DOI: 10.1021/acs.jpclett.6b02517] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 12/09/2016] [Indexed: 05/17/2023]
Abstract
Orbitals are invaluable in providing a model of bonding in molecules or between molecules and surfaces. Most present-day methods in computational chemistry begin by calculating the molecular orbitals of the system. To what extent have these mathematical objects analogues in the real world? To shed light on this intriguing question, we employ a photoemission tomography study on monolayers of 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) grown on three Ag surfaces. The characteristic photoelectron angular distribution enables us to assign individual molecular orbitals to the emission features. When comparing the resulting energy positions to density functional calculations, we observe deviations in the energy ordering. By performing complete active space calculations (CASSCF), we can explain the experimentally observed orbital ordering, suggesting the importance of static electron correlation beyond a (semi)local approximation. On the other hand, our results also show reality and robustness of the orbital concept, thereby making molecular orbitals accessible to experimental observations.
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Affiliation(s)
- P. Puschnig
- Institute
of Physics, University of Graz, NAWI-Graz, Universitätsplatz
5, 8010 Graz, Austria
- E-mail:
| | - A. D. Boese
- Institute
of Chemistry, University of Graz, NAWI Graz, Heinrichstraße 28/IV, 8010 Graz, Austria
| | - M. Willenbockel
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Jülich
Aachen
Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - M. Meyer
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Jülich
Aachen
Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - D. Lüftner
- Institute
of Physics, University of Graz, NAWI-Graz, Universitätsplatz
5, 8010 Graz, Austria
| | - E. M. Reinisch
- Institute
of Physics, University of Graz, NAWI-Graz, Universitätsplatz
5, 8010 Graz, Austria
| | - T. Ules
- Institute
of Physics, University of Graz, NAWI-Graz, Universitätsplatz
5, 8010 Graz, Austria
| | - G. Koller
- Institute
of Physics, University of Graz, NAWI-Graz, Universitätsplatz
5, 8010 Graz, Austria
| | - S. Soubatch
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Jülich
Aachen
Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - M. G. Ramsey
- Institute
of Physics, University of Graz, NAWI-Graz, Universitätsplatz
5, 8010 Graz, Austria
| | - F. S. Tautz
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Jülich
Aachen
Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
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30
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Koslowski S, Rosenblatt D, Kabakchiev A, Kuhnke K, Kern K, Schlickum U. Adsorption and electronic properties of pentacene on thin dielectric decoupling layers. Beilstein J Nanotechnol 2017; 8:1388-1395. [PMID: 28900594 PMCID: PMC5530602 DOI: 10.3762/bjnano.8.140] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 06/22/2017] [Indexed: 05/22/2023]
Abstract
With the increasing use of thin dielectric decoupling layers to study the electronic properties of organic molecules on metal surfaces, comparative studies are needed in order to generalize findings and formulate practical rules. In this paper we study the adsorption and electronic properties of pentacene deposited onto h-BN/Rh(111) and compare them with those of pentacene deposited onto KCl on various metal surfaces. When deposited onto KCl, the HOMO and LUMO energies of the pentacene molecules scale with the work functions of the combined KCl/metal surface. The magnitude of the variation between the respective KCl/metal systems indicates the degree of interaction of the frontier orbitals with the underlying metal. The results confirm that the so-called IDIS model developed by Willenbockel et al. applies not only to molecular layers on bare metal surfaces, but also to individual molecules on thin electronically decoupling layers. Depositing pentacene onto h-BN/Rh(111) results in significantly different adsorption characteristics, due to the topographic corrugation of the surface as well as the lateral electric fields it presents. These properties are reflected in the divergence from the aforementioned trend for the orbital energies of pentacene deposited onto h-BN/Rh(111), as well as in the different adsorption geometry. Thus, the highly desirable capacity of h-BN to trap molecules comes at the price of enhanced metal-molecule interaction, which decreases the HOMO-LUMO gap of the molecules. In spite of the enhanced interaction, the molecular orbitals are evident in scanning tunnelling spectroscopy (STS) and their shapes can be resolved by spectroscopic mapping.
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Affiliation(s)
- Sebastian Koslowski
- Max-Planck-Institut for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - Daniel Rosenblatt
- Max-Planck-Institut for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - Alexander Kabakchiev
- Max-Planck-Institut for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - Klaus Kuhnke
- Max-Planck-Institut for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - Klaus Kern
- Max-Planck-Institut for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
- Institut de Physique, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Uta Schlickum
- Max-Planck-Institut for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
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31
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Muller EA, Pollard B, Bechtel HA, van Blerkom P, Raschke MB. Infrared vibrational nanocrystallography and nanoimaging. Sci Adv 2016; 2:e1601006. [PMID: 27730212 PMCID: PMC5055384 DOI: 10.1126/sciadv.1601006] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/18/2016] [Indexed: 05/24/2023]
Abstract
Molecular solids and polymers can form low-symmetry crystal structures that exhibit anisotropic electron and ion mobility in engineered devices or biological systems. The distribution of molecular orientation and disorder then controls the macroscopic material response, yet it is difficult to image with conventional techniques on the nanoscale. We demonstrated a new form of optical nanocrystallography that combines scattering-type scanning near-field optical microscopy with both optical antenna and tip-selective infrared vibrational spectroscopy. From the symmetry-selective probing of molecular bond orientation with nanometer spatial resolution, we determined crystalline phases and orientation in aggregates and films of the organic electronic material perylenetetracarboxylic dianhydride. Mapping disorder within and between individual nanoscale domains, the correlative hybrid imaging of nanoscale heterogeneity provides insight into defect formation and propagation during growth in functional molecular solids.
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Affiliation(s)
- Eric A. Muller
- Department of Physics, Department of Chemistry, and JILA, University of Colorado, Boulder, CO 80309, USA
| | - Benjamin Pollard
- Department of Physics, Department of Chemistry, and JILA, University of Colorado, Boulder, CO 80309, USA
| | - Hans A. Bechtel
- Advanced Light Source Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Peter van Blerkom
- Department of Physics, Department of Chemistry, and JILA, University of Colorado, Boulder, CO 80309, USA
| | - Markus B. Raschke
- Department of Physics, Department of Chemistry, and JILA, University of Colorado, Boulder, CO 80309, USA
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32
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Stadtmüller B, Seidel J, Haag N, Grad L, Tusche C, van Straaten G, Franke M, Kirschner J, Kumpf C, Cinchetti M, Aeschlimann M. Modifying the Surface of a Rashba-Split Pb-Ag Alloy Using Tailored Metal-Organic Bonds. Phys Rev Lett 2016; 117:096805. [PMID: 27610875 DOI: 10.1103/physrevlett.117.096805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Indexed: 06/06/2023]
Abstract
Hybridization-related modifications of the first metal layer of a metal-organic interface are difficult to access experimentally and have been largely neglected so far. Here, we study the influence of specific chemical bonds (as formed by the organic molecules CuPc and PTCDA) on a Pb-Ag surface alloy. We find that delocalized van der Waals or weak chemical π-type bonds are not strong enough to alter the alloy, while localized σ-type bonds lead to a vertical displacement of the Pb surface atoms and to changes in the alloy's surface band structure. Our results provide an exciting platform for tuning the Rashba-type spin texture of surface alloys using organic molecules.
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Affiliation(s)
- Benjamin Stadtmüller
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger-Strasse 46, 67663 Kaiserslautern, Germany
- Graduate School of Excellence Materials Science in Mainz, Erwin Schroedinger Straße 46, 67663 Kaiserslautern, Germany
| | - Johannes Seidel
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger-Strasse 46, 67663 Kaiserslautern, Germany
| | - Norman Haag
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger-Strasse 46, 67663 Kaiserslautern, Germany
| | - Lisa Grad
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger-Strasse 46, 67663 Kaiserslautern, Germany
| | - Christian Tusche
- Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle, Germany
| | - Gerben van Straaten
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich-Aachen Research Alliance (JARA)-Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - Markus Franke
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich-Aachen Research Alliance (JARA)-Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - Jürgen Kirschner
- Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle, Germany
| | - Christian Kumpf
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich-Aachen Research Alliance (JARA)-Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - Mirko Cinchetti
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger-Strasse 46, 67663 Kaiserslautern, Germany
| | - Martin Aeschlimann
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger-Strasse 46, 67663 Kaiserslautern, Germany
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33
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Goiri E, Borghetti P, El-Sayed A, Ortega JE, de Oteyza DG. Multi-Component Organic Layers on Metal Substrates. Adv Mater 2016; 28:1340-1368. [PMID: 26662076 DOI: 10.1002/adma.201503570] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 08/31/2015] [Indexed: 05/28/2023]
Abstract
Increasingly high hopes are being placed on organic semiconductors for a variety of applications. Progress along these lines, however, requires the design and growth of increasingly complex systems with well-defined structural and electronic properties. These issues have been studied and reviewed extensively in single-component layers, but the focus is gradually shifting towards more complex and functional multi-component assemblies such as donor-acceptor networks. These blends show different properties from those of the corresponding single-component layers, and the understanding on how these properties depend on the different supramolecular environment of multi-component assemblies is crucial for the advancement of organic devices. Here, our understanding of two-dimensional multi-component layers on solid substrates is reviewed. Regarding the structure, the driving forces behind the self-assembly of these systems are described. Regarding the electronic properties, recent insights into how these are affected as the molecule's supramolecular environment changes are explained. Key information for the design and controlled growth of complex, functional multicomponent structures by self-assembly is summarized.
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Affiliation(s)
- Elizabeth Goiri
- Donostia International Physics Center, E-20018, Paseo Manuel Lardizabal 4, Donostia-San Sebastián, Spain
- Centro de Fisica de Materiales CSIC/UPV-EHU-Materials Physics Center, E-20018, Donostia-San Sebastián, Spain
| | - Patrizia Borghetti
- Donostia International Physics Center, E-20018, Paseo Manuel Lardizabal 4, Donostia-San Sebastián, Spain
- Centro de Fisica de Materiales CSIC/UPV-EHU-Materials Physics Center, E-20018, Donostia-San Sebastián, Spain
- Institut des NanoSciences de Paris, CNRS, UMR 7588, 4 Place Jussieu, Paris, 75005, France
| | - Afaf El-Sayed
- Centro de Fisica de Materiales CSIC/UPV-EHU-Materials Physics Center, E-20018, Donostia-San Sebastián, Spain
- Physics Dept., Faculty of Science, Al-Azhar University, 11754, Cairo, Egypt
| | - J Enrique Ortega
- Donostia International Physics Center, E-20018, Paseo Manuel Lardizabal 4, Donostia-San Sebastián, Spain
- Centro de Fisica de Materiales CSIC/UPV-EHU-Materials Physics Center, E-20018, Donostia-San Sebastián, Spain
- Universidad del Pais Vasco, Dpto. de Física Aplicada I, E-20018, Donostia-San Sebastián, Spain
| | - Dimas G de Oteyza
- Donostia International Physics Center, E-20018, Paseo Manuel Lardizabal 4, Donostia-San Sebastián, Spain
- Centro de Fisica de Materiales CSIC/UPV-EHU-Materials Physics Center, E-20018, Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, E-48011, Bilbao, Spain
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Weiß S, Lüftner D, Ules T, Reinisch EM, Kaser H, Gottwald A, Richter M, Soubatch S, Koller G, Ramsey MG, Tautz FS, Puschnig P. Exploring three-dimensional orbital imaging with energy-dependent photoemission tomography. Nat Commun 2015; 6:8287. [PMID: 26437297 DOI: 10.1038/ncomms9287] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 08/06/2015] [Indexed: 11/08/2022] Open
Abstract
Recently, it has been shown that experimental data from angle-resolved photoemission spectroscopy on oriented molecular films can be utilized to retrieve real-space images of molecular orbitals in two dimensions. Here, we extend this orbital tomography technique by performing photoemission initial state scans as a function of photon energy on the example of the brickwall monolayer of 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) on Ag(110). The overall dependence of the photocurrent on the photon energy can be well accounted for by assuming a plane wave for the final state. However, the experimental data, both for the highest occupied and the lowest unoccupied molecular orbital of PTCDA, exhibits an additional modulation attributed to final state scattering effects. Nevertheless, as these effects beyond a plane wave final state are comparably small, we are able, with extrapolations beyond the attainable photon energy range, to reconstruct three-dimensional images for both orbitals in agreement with calculations for the adsorbed molecule. Experimental data from angle-resolved photoemission spectroscopy can be utilized on molecular films to retrieve real-space images of molecular orbitals in two dimensions. Here, by scanning initial states as a function of photon energy, the authors can reconstruct three-dimensional orbital images.
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35
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Offenbacher H, Lüftner D, Ules T, Reinisch EM, Koller G, Puschnig P, Ramsey MG. Orbital tomography: Molecular band maps, momentum maps and the imaging of real space orbitals of adsorbed molecules. J Electron Spectros Relat Phenomena 2015; 204:92-101. [PMID: 26752804 PMCID: PMC4691939 DOI: 10.1016/j.elspec.2015.04.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The frontier orbitals of molecules are the prime determinants of their chemical, optical and electronic properties. Arguably, the most direct method of addressing the (filled) frontier orbitals is ultra-violet photoemission spectroscopy (UPS). Although UPS is a mature technique from the early 1970s on, the angular distribution of the photoemitted electrons was thought to be too complex to be analysed quantitatively. Recently angle resolved UPS (ARUPS) work on conjugated molecules both, in ordered thick films and chemisorbed monolayers, has shown that the angular (momentum) distribution of the photocurrent from orbital emissions can be simply understood. The approach, based on the assumption of a plane wave final state is becoming known as orbital tomography. Here we will demonstrate, with selected examples of pentacene (5A) and sexiphenyl (6P), the potential of orbital tomography. First it will be shown how the full angular distribution of the photocurrent (momentum map) from a specific orbital is related to the real space orbital by a Fourier transform. Examples of the reconstruction of 5A orbitals will be given and the procedure for recovering the lost phase information will be outlined. We then move to examples of sexiphenyl where we interrogate the original band maps of thick sexiphenyl in the light of our understanding of orbital tomography that has developed since then. With comparison to theoretical simulations of the molecular band maps, the molecular conformation and orientation will be concluded. New results for the sexiphenyl monolayer on Al(1 1 0) will then be presented. From the band maps it will be concluded that the molecule is planarised and adopts a tilted geometry. Finally the momentum maps down to HOMO-11 will be analysed and real space orbitals reconstructed.
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Affiliation(s)
| | | | | | | | - Georg Koller
- Institute of Physics, University of Graz, Universitätsplatz 5, 8010 Graz, Austria
| | | | - Michael G. Ramsey
- Institute of Physics, University of Graz, Universitätsplatz 5, 8010 Graz, Austria
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Liu W, Maaß F, Willenbockel M, Bronner C, Schulze M, Soubatch S, Tautz FS, Tegeder P, Tkatchenko A. Quantitative Prediction of Molecular Adsorption: Structure and Binding of Benzene on Coinage Metals. Phys Rev Lett 2015; 115:036104. [PMID: 26230807 DOI: 10.1103/physrevlett.115.036104] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Indexed: 05/09/2023]
Abstract
Interfaces between organic molecules and solid surfaces play a prominent role in heterogeneous catalysis, molecular sensors and switches, light-emitting diodes, and photovoltaics. The properties and the ensuing function of such hybrid interfaces often depend exponentially on molecular adsorption heights and binding strengths, calling for well-established benchmarks of these two quantities. Here we present systematic measurements that enable us to quantify the interaction of benzene with the Ag(111) coinage metal substrate with unprecedented accuracy (0.02 Å in the vertical adsorption height and 0.05 eV in the binding strength) by means of normal-incidence x-ray standing waves and temperature-programed desorption techniques. Based on these accurate experimental benchmarks for a prototypical molecule-solid interface, we demonstrate that recently developed first-principles calculations that explicitly account for the nonlocality of electronic exchange and correlation effects are able to determine the structure and stability of benzene on the Ag(111) surface within experimental error bars. Remarkably, such precise experiments and calculations demonstrate that despite different electronic properties of copper, silver, and gold, the binding strength of benzene is equal on the (111) surface of these three coinage metals. Our results suggest the existence of universal binding energy trends for aromatic molecules on surfaces.
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Affiliation(s)
- Wei Liu
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
- Nano Structural Materials Center, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu, China
| | - Friedrich Maaß
- Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Martin Willenbockel
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Christopher Bronner
- Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Michael Schulze
- Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Serguei Soubatch
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - F Stefan Tautz
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - Petra Tegeder
- Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Alexandre Tkatchenko
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
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37
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Egger DA, Liu ZF, Neaton JB, Kronik L. Reliable energy level alignment at physisorbed molecule-metal interfaces from density functional theory. Nano Lett 2015; 15:2448-55. [PMID: 25741626 PMCID: PMC4392703 DOI: 10.1021/nl504863r] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 03/04/2015] [Indexed: 05/17/2023]
Abstract
A key quantity for molecule-metal interfaces is the energy level alignment of molecular electronic states with the metallic Fermi level. We develop and apply an efficient theoretical method, based on density functional theory (DFT) that can yield quantitatively accurate energy level alignment information for physisorbed metal-molecule interfaces. The method builds on the "DFT+Σ" approach, grounded in many-body perturbation theory, which introduces an approximate electron self-energy that corrects the level alignment obtained from conventional DFT for missing exchange and correlation effects associated with the gas-phase molecule and substrate polarization. Here, we extend the DFT+Σ approach in two important ways: first, we employ optimally tuned range-separated hybrid functionals to compute the gas-phase term, rather than rely on GW or total energy differences as in prior work; second, we use a nonclassical DFT-determined image-charge plane of the metallic surface to compute the substrate polarization term, rather than the classical DFT-derived image plane used previously. We validate this new approach by a detailed comparison with experimental and theoretical reference data for several prototypical molecule-metal interfaces, where excellent agreement with experiment is achieved: benzene on graphite (0001), and 1,4-benzenediamine, Cu-phthalocyanine, and 3,4,9,10-perylene-tetracarboxylic-dianhydride on Au(111). In particular, we show that the method correctly captures level alignment trends across chemical systems and that it retains its accuracy even for molecules for which conventional DFT suffers from severe self-interaction errors.
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Affiliation(s)
- David A. Egger
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
| | - Zhen-Fei Liu
- Molecular Foundry and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Jeffrey B. Neaton
- Molecular Foundry and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department
of Physics, University of California, Berkeley, California 94720, United States
- Kavli Energy Nanosciences Institute at Berkeley, Berkeley, California 94720, United States
| | - Leeor Kronik
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
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