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Ma YX, Lai PT, Tang WM. Low-Temperature-Processed High-Performance Pentacene OTFTs with Optimal Nd-Ti Oxynitride Mixture as Gate Dielectric. MATERIALS 2022; 15:ma15062255. [PMID: 35329704 PMCID: PMC8951527 DOI: 10.3390/ma15062255] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 03/09/2022] [Accepted: 03/15/2022] [Indexed: 02/01/2023]
Abstract
When processed at a low temperature of 200 °C, organic thin-film transistors (OTFTs) with pentacene channel adopting high-k Neodymium-Titanium oxynitride mixtures (NdTiON) with various Ti contents as gate dielectrics are fabricated. The Ti content in the NdTiON is varied by co-sputtering a Ti target at 0 W, 10 W, 20 W and 30 W, respectively, while fixing the sputtering power of an Nd target at 45 W. High-performance OTFT is obtained for the 20 W-sputtered Ti, including a small threshold voltage of −0.71 V and high carrier mobility of 1.70 cm2/V·s. The mobility improvement for the optimal Ti content can be attributed to smoother dielectric surface and resultant larger overlying pentacene grains as reflected by Atomic Force Microscopy measurements. Moreover, this sample with the optimal Ti content shows much higher mobility than its counterpart processed at a higher temperature of 400 °C (0.8 cm2/V·s) because it has a thinner gate-dielectric/gate-electrode interlayer for stronger screening on the remote phonon scattering by the gate electrode. In addition, a high dielectric constant of around 10 is obtained for the NdTiON gate dielectric that contributes to a threshold voltage smaller than 1 V for the pentacene OTFT, implying the high potential of the Nd-Ti oxynitride in future high-performance organic devices.
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Affiliation(s)
- Yuan-Xiao Ma
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China;
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Island, Hong Kong 999077, China
| | - Pui-To Lai
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Island, Hong Kong 999077, China
- Correspondence: (P.-T.L.); (W.-M.T.)
| | - Wing-Man Tang
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Island, Hong Kong 999077, China
- Correspondence: (P.-T.L.); (W.-M.T.)
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2
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Kräuter J, Al-Shamery K. Bulk defect-dependent initial steps of acetone oxidation on rutile TiO2(110). Mol Phys 2021. [DOI: 10.1080/00268976.2021.1963870] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Jessica Kräuter
- Institute for Chemistry, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Katharina Al-Shamery
- Institute for Chemistry, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
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3
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Martínez-Casado R, Todorović M, Mallia G, Harrison NM, Pérez R. First Principles Calculations on the Stoichiometric and Defective (101) Anatase Surface and Upon Hydrogen and H 2Pc Adsorption: The Influence of Electronic Exchange and Correlation and of Basis Set Approximations. Front Chem 2019; 7:220. [PMID: 31106189 PMCID: PMC6499030 DOI: 10.3389/fchem.2019.00220] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 03/20/2019] [Indexed: 11/30/2022] Open
Abstract
Anatase TiO2 provides photoactivity with high chemical stability at a reasonable cost. Different methods have been used to enhance its photocatalytic activity by creating band gap states through the introduction of oxygen vacancies, hydrogen impurities, or the adorption of phthalocyanines, which are usually employed as organic dyes in dye-sensitized solar cells. Predicting how these interactions affect the electronic structure of anatase requires an efficient and robust theory. In order to document the efficiency and accuracy of commonly used approaches we have considered two widely used implementations of density functional theory (DFT), namely the all-electron linear combination of atomic orbitals (AE–LCAO) and the pseudo-potential plane waves (PP–PW) approaches, to calculate the properties of the stoichiometric and defective anatase TiO2 (101) surface. Hybrid functionals, and in particular HSE, lead to a computed band gap in agreement with that measured by using UV adsorption spectroscopy. When using PBE+U, the gap is underestimated by 20 % but the computed position of defect induced gap states relative to the conduction band minimum (CBM) are found to be in good agreement with those calculated using hybrid functionals. These results allow us to conclude that hybrid functionals based on the use of AE–LCAO provide an efficient and robust approach for predicting trends in the band gap and the position of gap states in large model systems. We extend this analysis to surface adsorption and use the AE–LCAO approach with the hybrid functional HSED3 to study the adsorption of the phthalocyanine H2Pc on anatase (101). Our results suggest that H2Pc prefers to be adsorbed on the surface Ti5c rows of anatase (101), in agreement with that seen in recent STM experiments on rutile (110).
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Affiliation(s)
- Ruth Martínez-Casado
- Departamento de Física de Materiales, Universidad Complutense de Madrid, Madrid, Spain.,Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain
| | | | - Giuseppe Mallia
- Department of Chemistry, Imperial College London, White City, London, United Kingdom
| | - Nicholas M Harrison
- Department of Chemistry, Imperial College London, White City, London, United Kingdom
| | - Rubén Pérez
- Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain.,Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, Spain
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4
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Jöhr R, Hinaut A, Pawlak R, Zajac Ł, Olszowski P, Such B, Glatzel T, Zhang J, Muntwiler M, Bergkamp JJ, Mateo LM, Decurtins S, Liu SX, Meyer E. Thermally induced anchoring of a zinc-carboxyphenylporphyrin on rutile TiO2 (110). J Chem Phys 2017. [DOI: 10.1063/1.4982936] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Res Jöhr
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Antoine Hinaut
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Rémy Pawlak
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Łukasz Zajac
- Physics Department, Jagiellonian University, Ul. Prof. St. Lojasiewicza 11, 30-348 Krakow, Poland
| | - Piotr Olszowski
- Physics Department, Jagiellonian University, Ul. Prof. St. Lojasiewicza 11, 30-348 Krakow, Poland
| | - Bartosz Such
- Physics Department, Jagiellonian University, Ul. Prof. St. Lojasiewicza 11, 30-348 Krakow, Poland
| | - Thilo Glatzel
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Jun Zhang
- Paul Scherrer Institute, 5232 Villigen, Switzerland
| | | | - Jesse J. Bergkamp
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Luis-Manuel Mateo
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Silvio Decurtins
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Shi-Xia Liu
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Ernst Meyer
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
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5
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Schön P, Ctistis G, Bakker W, Luthe G. Nanoparticular surface-bound PCBs, PCDDs, and PCDFs-a novel class of potentially higher toxic POPs. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2017; 24:12758-12766. [PMID: 26939687 DOI: 10.1007/s11356-016-6211-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 01/31/2016] [Indexed: 06/05/2023]
Abstract
In a previous study, Env Sci Poll Res:1-7, 2015 showed that polychlorinated biphenyls (PCBs), polychlorinated dibenzo dioxins (PCDDs), and polychlorinated dibenzo furanes (PCDFs) are found in commercially available (nano) particular titanium dioxide as a result of the fabrication. Here, we give a brief perspective and reason the toxicity of these new classes of persistent organic pollutants (POPs) by reviewing also their nanoparticular properties, such as surface-to-volume ratio, photocatalytic activity, polarity shifts, and stealth effect. These insights point towards a new class of POPs and toxicologic effects, which are related to the size but not a result of nanotechnology itself. We pave the way to the understanding of until now unresolved very complex phenomena, such as the indoor exposure, formation, and transformation of POP and sick-building syndrome. This is a fundamental message for nanotoxicology and kinetics and should be taken into account when determining the toxicity of nanomaterials and POPs separately and as a combination.
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Affiliation(s)
- Peter Schön
- NanoBioInterface Research Group, School of Life Science, Engineering, and Design, Saxion University of Applied Sciences, M.H. Tromplaan 28, P.O. Box 70.000, 7500 KB, Enschede, The Netherlands
- Materials Science and Technology of Polymers, MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE, Enschede, The Netherlands
| | - Georgios Ctistis
- NanoBioInterface Research Group, School of Life Science, Engineering, and Design, Saxion University of Applied Sciences, M.H. Tromplaan 28, P.O. Box 70.000, 7500 KB, Enschede, The Netherlands
- Complex Photonic Systems (COPS), MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE, Enschede, The Netherlands
| | - Wouter Bakker
- NanoBioInterface Research Group, School of Life Science, Engineering, and Design, Saxion University of Applied Sciences, M.H. Tromplaan 28, P.O. Box 70.000, 7500 KB, Enschede, The Netherlands
| | - Gregor Luthe
- Department of Occupational and Environmental Health, The University of Iowa, 100 Oakdale Campus, Iowa City, IA, 52242, USA.
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa City, IA, 52242, USA.
- Luthe Pharma, Fabrikstrasse 2, 48599, Gronau, Germany.
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6
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Olszowski P, Zajac L, Godlewski S, Such B, Pawlak R, Hinaut A, Jöhr R, Glatzel T, Meyer E, Szymonski M. Ordering of Zn-centered porphyrin and phthalocyanine on TiO 2(011): STM studies. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2017; 8:99-107. [PMID: 28144569 PMCID: PMC5238625 DOI: 10.3762/bjnano.8.11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 12/21/2016] [Indexed: 05/04/2023]
Abstract
Zn(II)phthalocyanine molecules (ZnPc) were thermally deposited on a rutile TiO2(011) surface and on Zn(II)meso-tetraphenylporphyrin (ZnTPP) wetting layers at room temperature and after elevated temperature thermal processing. The molecular homo- and heterostructures were characterized by high-resolution scanning tunneling microscopy (STM) at room temperature and their geometrical arrangement and degree of ordering are compared with the previously studied copper phthalocyanine (CuPc) and ZnTPP heterostructures. It was found that the central metal atom may play some role in ordering and growth of phthalocyanine/ZnTPP heterostructures, causing differences in stability of upright standing ZnPc versus CuPc molecular chains at given thermal annealing conditions.
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Affiliation(s)
- Piotr Olszowski
- Research Centre for Nanometer-Scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy, and Applied Computer Science, Jagiellonian University, Lojasiewicza 11, 30-348 Krakow, Poland
| | - Lukasz Zajac
- Research Centre for Nanometer-Scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy, and Applied Computer Science, Jagiellonian University, Lojasiewicza 11, 30-348 Krakow, Poland
| | - Szymon Godlewski
- Research Centre for Nanometer-Scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy, and Applied Computer Science, Jagiellonian University, Lojasiewicza 11, 30-348 Krakow, Poland
| | - Bartosz Such
- Research Centre for Nanometer-Scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy, and Applied Computer Science, Jagiellonian University, Lojasiewicza 11, 30-348 Krakow, Poland
| | - Rémy Pawlak
- University of Basel, Department of Physics, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Antoine Hinaut
- University of Basel, Department of Physics, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Res Jöhr
- University of Basel, Department of Physics, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Thilo Glatzel
- University of Basel, Department of Physics, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Ernst Meyer
- University of Basel, Department of Physics, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Marek Szymonski
- Research Centre for Nanometer-Scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy, and Applied Computer Science, Jagiellonian University, Lojasiewicza 11, 30-348 Krakow, Poland
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7
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Zając Ł, Olszowski P, Godlewski S, Such B, Jöhr R, Pawlak R, Hinaut A, Glatzel T, Meyer E, Szymonski M. Ordered heteromolecular overlayers formed by metal phthalocyanines and porphyrins on rutile titanium dioxide surface studied at room temperature. J Chem Phys 2016; 143:224702. [PMID: 26671391 DOI: 10.1063/1.4936658] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Molecular heterostructures are formed from meso-tetraphenyl porphyrins-Zn(II) (ZnTPP) and Cu(II)-phthalocyanines (CuPc) on the rutile TiO2(011) surface. We demonstrate that ZnTPP molecules form a quasi-ordered wetting layer with flat-lying molecules, which provides the support for growth of islands comprised of upright CuPc molecules. The incorporation of the ZnTPP layer and the growth of heterostructures increase the stability of the system and allow for room temperature scanning tunneling microscopy (STM) measurements, which is contrasted with unstable STM probing of only CuPc species on TiO2. We demonstrate that within the CuPc layer the molecules arrange in two phases and we identify molecular dimers as basic building blocks of the dominant structural phase.
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Affiliation(s)
- Łukasz Zając
- Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, ul. S. Łojasiewicza 11, 30-348 Krakow, Poland
| | - Piotr Olszowski
- Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, ul. S. Łojasiewicza 11, 30-348 Krakow, Poland
| | - Szymon Godlewski
- Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, ul. S. Łojasiewicza 11, 30-348 Krakow, Poland
| | - Bartosz Such
- Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, ul. S. Łojasiewicza 11, 30-348 Krakow, Poland
| | - Res Jöhr
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Rémy Pawlak
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Antoine Hinaut
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Thilo Glatzel
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Ernst Meyer
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Marek Szymonski
- Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, ul. S. Łojasiewicza 11, 30-348 Krakow, Poland
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8
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Xu T, Schwarz M, Werner K, Mohr S, Amende M, Libuda J. Structure-Dependent Anchoring of Organic Molecules to Atomically Defined Oxide Surfaces: Phthalic Acid on Co3O4(111), CoO(100), and CoO(111). Chemistry 2016; 22:5384-96. [PMID: 26934313 DOI: 10.1002/chem.201504810] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Indexed: 12/21/2022]
Abstract
We have performed a model study to explore the influence of surface structure on the anchoring of organic molecules on oxide materials. Specifically, we have investigated the adsorption of phthalic acid (PA) on three different, well-ordered, and atomically defined cobalt oxide surfaces, namely 1) Co3O4(111), 2) CoO(111), and 3) CoO(100) on Ir(100). PA was deposited by physical vapor deposition (PVD). The formation of the PA films and interfacial reactions were monitored in situ during growth by isothermal time-resolved IR reflection absorption spectroscopy (TR-IRAS) under ultrahigh vacuum (UHV) conditions. We observed a pronounced structure dependence on the three surfaces with three distinctively different binding geometries and characteristic differences depending on the temperature and coverage. 1) PA initially binds to Co3O4(111) through the formation of a chelating bis-carboxylate with the molecular plane oriented perpendicularly to the surface. Similar species were observed both at low temperature (130 K) and at room temperature (300 K). With increasing exposure, chelating mono-carboxylates became more abundant and partially replaced the bis-carboxylate. 2) PA binds to CoO(100) in the form of a bridging bis-carboxylate for low coverage. Upon prolonged deposition of PA at low temperature, the bis-carboxylates were converted into mono-carboxylate species. In contrast, the bis-carboxylate layer was very stable at 300 K. 3) For CoO(111) we observed a temperature-dependent change in the adsorption mechanism. Although PA binds as a mono-carboxylate in a bridging bidentate fashion at low temperature (130 K), a strongly distorted bis-carboxylate was formed at 300 K, possibly as a result of temperature-dependent restructuring of the surface. The results show that the adsorption geometry of PA depends on the atomic structure of the oxide surface. The structure dependence can be rationalized by the different arrangements of cobalt ions at the three surfaces.
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Affiliation(s)
- Tao Xu
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany), Fax
| | - Matthias Schwarz
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany), Fax
| | - Kristin Werner
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany), Fax
| | - Susanne Mohr
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany), Fax
| | - Max Amende
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany), Fax
| | - Jörg Libuda
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany), Fax. .,Erlangen Catalysis Resource Center and Interdisciplinary Center Interface Controlled Processes, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany.
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Xu T, Schwarz M, Werner K, Mohr S, Amende M, Libuda J. The surface structure matters: thermal stability of phthalic acid anchored to atomically-defined cobalt oxide films. Phys Chem Chem Phys 2016; 18:10419-27. [DOI: 10.1039/c6cp00296j] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The atomic structure of cobalt oxide surfaces influence the ordering and thermal stability of anchored phthalic acid.
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Affiliation(s)
- Tao Xu
- Lehrstuhl für Physikalische Chemie II
- Friedrich-Alexander-Universität Erlangen-Nürnberg
- D-91058 Erlangen
- Germany
| | - Matthias Schwarz
- Lehrstuhl für Physikalische Chemie II
- Friedrich-Alexander-Universität Erlangen-Nürnberg
- D-91058 Erlangen
- Germany
| | - Kristin Werner
- Lehrstuhl für Physikalische Chemie II
- Friedrich-Alexander-Universität Erlangen-Nürnberg
- D-91058 Erlangen
- Germany
| | - Susanne Mohr
- Lehrstuhl für Physikalische Chemie II
- Friedrich-Alexander-Universität Erlangen-Nürnberg
- D-91058 Erlangen
- Germany
| | - Max Amende
- Lehrstuhl für Physikalische Chemie II
- Friedrich-Alexander-Universität Erlangen-Nürnberg
- D-91058 Erlangen
- Germany
| | - Jörg Libuda
- Lehrstuhl für Physikalische Chemie II
- Friedrich-Alexander-Universität Erlangen-Nürnberg
- D-91058 Erlangen
- Germany
- Erlangen Catalysis Resource Center and Interdisciplinary Center Interface Controlled Processes
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10
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Jöhr R, Hinaut A, Pawlak R, Sadeghi A, Saha S, Goedecker S, Such B, Szymonski M, Meyer E, Glatzel T. Characterization of individual molecular adsorption geometries by atomic force microscopy: Cu-TCPP on rutile TiO2 (110). J Chem Phys 2015; 143:094202. [PMID: 26342363 DOI: 10.1063/1.4929608] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Functionalized materials consisting of inorganic substrates with organic adsorbates play an increasing role in emerging technologies like molecular electronics or hybrid photovoltaics. For such applications, the adsorption geometry of the molecules under operating conditions, e.g., ambient temperature, is crucial because it influences the electronic properties of the interface, which in turn determine the device performance. So far detailed experimental characterization of adsorbates at room temperature has mainly been done using a combination of complementary methods like photoelectron spectroscopy together with scanning tunneling microscopy. However, this approach is limited to ensembles of adsorbates. In this paper, we show that the characterization of individual molecules at room temperature, comprising the determination of the adsorption configuration and the electrostatic interaction with the surface, can be achieved experimentally by atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). We demonstrate this by identifying two different adsorption configurations of isolated copper(ii) meso-tetra (4-carboxyphenyl) porphyrin (Cu-TCPP) on rutile TiO2 (110) in ultra-high vacuum. The local contact potential difference measured by KPFM indicates an interfacial dipole due to electron transfer from the Cu-TCPP to the TiO2. The experimental results are verified by state-of-the-art first principles calculations. We note that the improvement of the AFM resolution, achieved in this work, is crucial for such accurate calculations. Therefore, high resolution AFM at room temperature is promising for significantly promoting the understanding of molecular adsorption.
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Affiliation(s)
- Res Jöhr
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Antoine Hinaut
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Rémy Pawlak
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Ali Sadeghi
- Physics Department, Shahid Beheshti University, G. C., Evin, 19839 Tehran, Iran
| | - Santanu Saha
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Stefan Goedecker
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Bartosz Such
- Department of Physics, Jagiellonian University, Lojasiewicza 11, 30-348 Krakow, Poland
| | - Marek Szymonski
- Department of Physics, Jagiellonian University, Lojasiewicza 11, 30-348 Krakow, Poland
| | - Ernst Meyer
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Thilo Glatzel
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
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11
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Mohr S, Xu T, Döpper T, Laurin M, Görling A, Libuda J. Molecular Orientation and Structural Transformations in Phthalic Anhydride Thin Films on MgO(100)/Ag(100). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:7806-7814. [PMID: 26102241 DOI: 10.1021/acs.langmuir.5b01392] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Structural control of organic thin films on dielectric substrates is the key to tailoring the physical properties of hybrid materials, for example, for application in solar energy conversion, molecular electronics, or catalysis. In this work, we investigate the molecular orientation of phthalic anhydride (PAA) films on atomically well-defined MgO(100) on Ag(100) using temperature-programmed infrared reflection absorption spectroscopy (TP-IRAS) in combination with density-functional theory (DFT). A robust procedure is presented to determine the orientation of the PAA molecules, which relies on the intensity ratios of vibrational bands only. We show that even at deposition temperatures of 110 K, the PAA multilayer grows with a specific molecular orientation; that is, the PAA molecular plane is preferentially aligned parallel with the MgO surface. No change of molecular orientation occurs up to a temperature of 145 K. Between 145 and 160 K, the film restructures adopting a nearly flat-lying molecular orientation. Between 170 and 205 K, the film undergoes a second structural transition to a crystalline phase. This transition is associated with a pronounced molecular reorientation. The molecules adopt a tilted orientation and, simultaneously, rotate around their C2 axes. The reorientation behavior suggests that the molecular orientation in the crystalline phase is controlled by the interaction with the MgO(100) substrate. At higher temperature, no further restructuring is observed until the PAA multilayer desorbs at temperatures above 230 K.
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Affiliation(s)
- Susanne Mohr
- †Lehrstuhl für Physikalische Chemie II, ‡Lehrstuhl für Theoretische Chemie, and §Erlangen Catalysis Resource Center and Interdisciplinary Center Interface-Controlled Processes, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, D-91058 Erlangen, Germany
| | - Tao Xu
- †Lehrstuhl für Physikalische Chemie II, ‡Lehrstuhl für Theoretische Chemie, and §Erlangen Catalysis Resource Center and Interdisciplinary Center Interface-Controlled Processes, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, D-91058 Erlangen, Germany
| | - Tibor Döpper
- †Lehrstuhl für Physikalische Chemie II, ‡Lehrstuhl für Theoretische Chemie, and §Erlangen Catalysis Resource Center and Interdisciplinary Center Interface-Controlled Processes, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, D-91058 Erlangen, Germany
| | - Mathias Laurin
- †Lehrstuhl für Physikalische Chemie II, ‡Lehrstuhl für Theoretische Chemie, and §Erlangen Catalysis Resource Center and Interdisciplinary Center Interface-Controlled Processes, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, D-91058 Erlangen, Germany
| | - Andreas Görling
- †Lehrstuhl für Physikalische Chemie II, ‡Lehrstuhl für Theoretische Chemie, and §Erlangen Catalysis Resource Center and Interdisciplinary Center Interface-Controlled Processes, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, D-91058 Erlangen, Germany
| | - Jörg Libuda
- †Lehrstuhl für Physikalische Chemie II, ‡Lehrstuhl für Theoretische Chemie, and §Erlangen Catalysis Resource Center and Interdisciplinary Center Interface-Controlled Processes, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, D-91058 Erlangen, Germany
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Godlewski S, Prauzner-Bechcicki JS, Glatzel T, Meyer E, Szymoński M. Transformations of PTCDA structures on rutile TiO2 induced by thermal annealing and intermolecular forces. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2015; 6:1498-1507. [PMID: 26199854 PMCID: PMC4505301 DOI: 10.3762/bjnano.6.155] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 06/25/2015] [Indexed: 06/06/2023]
Abstract
Transformations of molecular structures formed by perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) molecules on a rutile TiO2(110) surface are studied with low-temperature scanning tunnelling microscopy. We demonstrate that metastable molecular assemblies transform into differently ordered structures either due to additional energy provided by thermal annealing or when the influence of intermolecular forces is increased by the enlarged amount of deposited molecules. Proper adjustment of molecular coverage and substrate temperature during deposition allows for fabrication of desired assemblies. Differences between PTCDA/TiO2(110) and PTCDA/TiO2(011) systems obtained through identical experimental procedures are discussed.
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Affiliation(s)
- Szymon Godlewski
- Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow, Poland
| | - Jakub S Prauzner-Bechcicki
- Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow, Poland
| | - Thilo Glatzel
- Department of Physics, University of Basel, Klingelbergstr. 82, 4056 Basel, Switzerland
| | - Ernst Meyer
- Department of Physics, University of Basel, Klingelbergstr. 82, 4056 Basel, Switzerland
| | - Marek Szymoński
- Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow, Poland
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Dreiser J. Molecular lanthanide single-ion magnets: from bulk to submonolayers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:183203. [PMID: 25893740 DOI: 10.1088/0953-8984/27/18/183203] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Single-ion magnets (SIMs) are mononuclear molecular complexes exhibiting slow relaxation of magnetization. They are currently attracting a lot of interest because of potential applications in spintronics and quantum information processing. However, exploiting SIMs in, e.g. molecule-inorganic hybrid devices requires a fundamental understanding of the effects of molecule-substrate interactions on the SIM magnetic properties. In this review the properties of lanthanide SIMs in the bulk crystalline phase and deposited on surfaces in the (sub)monolayer regime are discussed. As a starting point trivalent lanthanide ions in a ligand field will be described, and the challenges in characterizing the ligand field are illustrated with a focus on several spectroscopic techniques which are able to give direct information on the ligand-field split energy levels. Moreover, the dominant mechanisms of magnetization relaxation in the bulk phase are discussed followed by an overview of SIMs relevant for surface deposition. Further, a short introduction will be given on x-ray absorption spectroscopy, x-ray magnetic circular dichroism and scanning tunneling microscopy. Finally, the recent experiments on surface-deposited SIMs will be reviewed, along with a discussion of future perspectives.
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Affiliation(s)
- J Dreiser
- Ecole Polytechnique Fédérale de Lausanne, ICMP, Station 3, CH-1015 Lausanne, Switzerland. Paul Scherrer Institut, Swiss Light Source, CH-5232 Villigen PSI, Switzerland
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Pshenichnyuk SA, Modelli A, Lazneva EF, Komolov AS. Resonance electron attachment to tetracyanoquinodimethane. J Phys Chem A 2014; 118:6810-8. [PMID: 25121340 DOI: 10.1021/jp505841c] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Resonance interaction of low energy (0-14 eV) electrons with gas-phase 7,7,8,8-tetracyanoquinodimethane (TCNQ) was investigated using dissociative electron attachment (DEA) spectroscopy. Spectral features associated with formation of long-lived TCNQ molecular negative ions are detected at incident electron energies of 0.3, 1.3, and 3.0 eV. A variety of negative fragments is observed around 4 eV, and slow (microseconds) dissociative decay channels are detected at about 3 eV, in competition with simple re-emission of the captured electron. The average electron detachment time from the TCNQ(-) negative ions formed at 3 eV was evaluated to be 250 μs. The experimental findings are interpreted with the support of density functional theory (DFT) calculations of the empty orbital energies, scaled with an empirical equation, and by comparison with earlier electron transmission spectroscopy (ETS) data. A possible mechanism for the unusual formation of long-lived molecular anions above zero energy (up to 3 eV) is briefly discussed. The present results on the interactions between electrons and isolated TCNQ molecules could give more insight into processes observed in TCNQ adsorbates under conditions of excess negative charge. In particular, electron-stimulated surface reactions are hypothesized, likely occurring when condensed TCNQ molecules are exposed to electron beam irradiation.
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Affiliation(s)
- Stanislav A Pshenichnyuk
- Institute of Molecule and Crystal Physics, Ufa Research Centre, Russian Academy of Sciences , Prospeκt Oktyabrya 151, 450075 Ufa, Russia
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