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Franz M, Chandola S, Koy M, Zielinski R, Aldahhak H, Das M, Freitag M, Gerstmann U, Liebig D, Hoffmann AK, Rosin M, Schmidt WG, Hogan C, Glorius F, Esser N, Dähne M. Controlled growth of ordered monolayers of N-heterocyclic carbenes on silicon. Nat Chem 2021; 13:828-835. [PMID: 34155377 DOI: 10.1038/s41557-021-00721-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 04/30/2021] [Indexed: 11/09/2022]
Abstract
N-Heterocyclic carbenes (NHCs) are promising modifiers and anchors for surface functionalization and offer some advantages over thiol-based systems. Because of their strong binding affinity and high electron donation, NHCs can dramatically change the properties of the surfaces to which they are bonded. Highly ordered NHC monolayers have so far been limited to metal surfaces. Silicon, however, remains the element of choice in semiconductor devices and its modification is therefore of utmost importance for electronic industries. Here, a comprehensive study on the adsorption of NHCs on silicon is presented. We find covalently bound NHC molecules in an upright adsorption geometry and demonstrate the formation of highly ordered monolayers exhibiting good thermal stability and strong work function reductions. The structure and ordering of the monolayers is controlled by the substrate geometry and reactivity and in particular by the NHC side groups. These findings pave the way towards a tailor-made organic functionalization of silicon surfaces and, thanks to the high modularity of NHCs, new electronic and optoelectronic applications.
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Affiliation(s)
- Martin Franz
- Institut für Festkörperphysik, Technische Universität Berlin, Berlin, Germany
| | - Sandhya Chandola
- Institut für Festkörperphysik, Technische Universität Berlin, Berlin, Germany.,Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, Paderborn, Germany.,Helmholtz-Zentrum Berlin für Materialen und Energie GmbH, Berlin, Germany
| | - Maximilian Koy
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Robert Zielinski
- Institut für Festkörperphysik, Technische Universität Berlin, Berlin, Germany.,Leibniz-Institut für Analytische Wissenschaften - ISAS e.V., Berlin, Germany
| | - Hazem Aldahhak
- Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, Paderborn, Germany
| | - Mowpriya Das
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Matthias Freitag
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Uwe Gerstmann
- Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, Paderborn, Germany
| | - Denise Liebig
- Institut für Festkörperphysik, Technische Universität Berlin, Berlin, Germany
| | | | - Maximilian Rosin
- Institut für Festkörperphysik, Technische Universität Berlin, Berlin, Germany
| | - Wolf Gero Schmidt
- Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, Paderborn, Germany
| | - Conor Hogan
- Istituto di Struttura della Materia-CNR (ISM-CNR), Rome, Italy.,Department of Physics, Università di Roma 'Tor Vergata', Rome, Italy
| | - Frank Glorius
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Münster, Germany.
| | - Norbert Esser
- Institut für Festkörperphysik, Technische Universität Berlin, Berlin, Germany. .,Leibniz-Institut für Analytische Wissenschaften - ISAS e.V., Berlin, Germany.
| | - Mario Dähne
- Institut für Festkörperphysik, Technische Universität Berlin, Berlin, Germany.
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2
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Niederhausen J, MacQueen RW, Lips K, Aldahhak H, Schmidt WG, Gerstmann U. Tetracene Ultrathin Film Growth on Hydrogen-Passivated Silicon. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:9099-9113. [PMID: 32659091 DOI: 10.1021/acs.langmuir.0c01154] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Inorganic-organic interfaces are important for enhancing the power conversion efficiency of silicon-based solar cells through singlet exciton fission (SF). We elucidated the structure of the first monolayers of tetracene (Tc), an SF molecule, on hydrogen-passivated Si(111) [H-Si(111)] and hydrogenated amorphous Si (a-Si:H) by combining near-edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) experiments with density functional theory (DFT) calculations. For samples grown at or below substrate temperatures of 265 K, the resulting ultrathin Tc films are dominated by almost upright-standing molecules. The molecular arrangement is very similar to the Tc bulk phase, with only a slightly higher average angle between the conjugated molecular plane normal and the surface normal (α) around 77°. Judging from carbon K-edge X-ray absorption spectra, the orientation of the Tc molecules are almost identical when grown on H-Si(111) and a-Si:H substrates as well as for (sub)mono- to several-monolayer coverages. Annealing to room temperature, however, changes the film structure toward a smaller α of about 63°. A detailed DFT-assisted analysis suggests that this structural transition is correlated with a lower packing density and requires a well-chosen amount of thermal energy. Therefore, we attribute the resulting structure to a distinct monolayer configuration that features less inclined, but still well-ordered molecules. The larger overlap with the substrate wave functions makes this arrangement attractive for an optimized interfacial electron transfer in SF-assisted silicon solar cells.
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Affiliation(s)
- Jens Niederhausen
- Department ASPIN, Helmholtz-Zentrum Berlin für Materialen und Energie GmbH, Berlin, Germany
| | - Rowan W MacQueen
- Department ASPIN, Helmholtz-Zentrum Berlin für Materialen und Energie GmbH, Berlin, Germany
| | - Klaus Lips
- Department ASPIN, Helmholtz-Zentrum Berlin für Materialen und Energie GmbH, Berlin, Germany
| | - Hazem Aldahhak
- Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany
| | - Wolf Gero Schmidt
- Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany
| | - Uwe Gerstmann
- Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany
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3
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Aldahhak H, Powroźnik P, Pander P, Jakubik W, Dias FB, Schmidt WG, Gerstmann U, Krzywiecki M. Toward Efficient Toxic-Gas Detectors: Exploring Molecular Interactions of Sarin and Dimethyl Methylphosphonate with Metal-Centered Phthalocyanine Structures. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2020; 124:6090-6102. [PMID: 32952768 PMCID: PMC7497713 DOI: 10.1021/acs.jpcc.9b11116] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 02/11/2020] [Indexed: 05/03/2023]
Abstract
The rapid and reliable detection of lethal agents such as sarin is of increasing importance. Here, density-functional theory (DFT) is used to compare the interaction of sarin with single-metal-centered phthalocyanine (MPc) and MPc layer structures to a benign model system, i.e., the adsorption of dimethyl methylphosphonate (DMMP). The calculations show that sarin and DMMP behave nearly identical to the various MPcs studied. Among NiPc, CuPc, CoPc, and zinc phthalocyanine (ZnPc), we find the interaction of both sarin and DMMP to be the strongest with ZnPc, both in terms of interaction energy and adsorption-induced work function changes. ZnPc is thus proposed as a promising sensor for sarin detection. Using X-ray photoelectron spectroscopy, the theoretically predicted charge transfer from DMMP to ZnPc is confirmed and identified as a key component in the sensing mechanism.
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Affiliation(s)
- Hazem Aldahhak
- Lehrstuhl
für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany
- E-mail:
| | - Paulina Powroźnik
- Lehrstuhl
für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany
- Institute
of Physics—Center for Science and Education, Silesian University of Technology, S. Konarskiego Str. 22B, 44-100 Gliwice, Poland
| | - Piotr Pander
- Department
of Physics, Durham University, South Road, Durham DH1 3LE, United
Kingdom
| | - Wiesław Jakubik
- Institute
of Physics—Center for Science and Education, Silesian University of Technology, S. Konarskiego Str. 22B, 44-100 Gliwice, Poland
| | - Fernando B. Dias
- Department
of Physics, Durham University, South Road, Durham DH1 3LE, United
Kingdom
| | - Wolf Gero Schmidt
- Lehrstuhl
für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany
| | - Uwe Gerstmann
- Lehrstuhl
für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany
| | - Maciej Krzywiecki
- Institute
of Physics—Center for Science and Education, Silesian University of Technology, S. Konarskiego Str. 22B, 44-100 Gliwice, Poland
- E-mail:
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4
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Paszkiewicz M, Biktagirov T, Aldahhak H, Allegretti F, Rauls E, Schöfberger W, Schmidt WG, Barth JV, Gerstmann U, Klappenberger F. Unraveling the Oxidation and Spin State of Mn-Corrole through X-ray Spectroscopy and Quantum Chemical Analysis. J Phys Chem Lett 2018; 9:6412-6420. [PMID: 30362761 DOI: 10.1021/acs.jpclett.8b02525] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The interplay between Mn ions and corrole ligands gives rise to complex scenarios regarding the metal centers' electronic properties expressing a range of high oxidation states and spin configurations. The resulting potential of Mn-corroles for applications such as catalysts or fuel cells has recently been demonstrated. However, despite being crucial for their functionality, the electronic structure of Mn-corroles is often hardly accessible with traditional techniques and thus is still under debate, especially under interfacial conditions. Here, we unravel the electronic ground state of the prototypical Mn-5,10,15-tris(pentafluorophenyl)corrole complex through X-ray spectroscopic investigations of ultrapure thin films and quantum chemical analysis. The theory-based interpretation of Mn photoemission and absorption fine structure spectra (3s and 2p and L2,3-edge, respectively) evidence a Mn(III) oxidation state with an S = 2 high-spin configuration. By referencing density functional theory calculations with the experiments, we lay the basis for extending our approach to the characterization of complex interfaces.
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Affiliation(s)
- Mateusz Paszkiewicz
- Physics Department E20 , Technical University of Munich , James-Franck-Strasse 1 , 85748 Garching , Germany
| | - Timur Biktagirov
- Department of Physics , Paderborn University , Warburger Strasse 100 , 33098 Paderborn , Germany
| | - Hazem Aldahhak
- Department of Physics , Paderborn University , Warburger Strasse 100 , 33098 Paderborn , Germany
| | - Francesco Allegretti
- Physics Department E20 , Technical University of Munich , James-Franck-Strasse 1 , 85748 Garching , Germany
| | - Eva Rauls
- Institutt for Matematikk og Fysikk , University of Stavanger , 4036 Stavanger , Norway
| | - Wolfgang Schöfberger
- Institute of Organic Chemistry , Johannes Kepler University , Altenberger Straße 69 , 4040 Linz , Austria
| | - Wolf Gero Schmidt
- Department of Physics , Paderborn University , Warburger Strasse 100 , 33098 Paderborn , Germany
| | - Johannes V Barth
- Physics Department E20 , Technical University of Munich , James-Franck-Strasse 1 , 85748 Garching , Germany
| | - Uwe Gerstmann
- Department of Physics , Paderborn University , Warburger Strasse 100 , 33098 Paderborn , Germany
| | - Florian Klappenberger
- Physics Department E20 , Technical University of Munich , James-Franck-Strasse 1 , 85748 Garching , Germany
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