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Trifiletti V, Massetti M, Calloni A, Luong S, Pianetti A, Milita S, Schroeder BC, Bussetti G, Binetti S, Fabiano S, Fenwick O. Bismuth-Based Perovskite Derivates with Thermal Voltage Exceeding 40 mV/K. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2024; 128:5408-5417. [PMID: 38595774 PMCID: PMC11000217 DOI: 10.1021/acs.jpcc.3c06324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 03/01/2024] [Accepted: 03/04/2024] [Indexed: 04/11/2024]
Abstract
Heat is an inexhaustible source of energy, and it can be exploited by thermoelectronics to produce electrical power or electrical responses. The search for a low-cost thermoelectric material that could achieve high efficiencies and can also be straightforwardly scalable has turned significant attention to the halide perovskite family. Here, we report the thermal voltage response of bismuth-based perovskite derivates and suggest a path to increase the electrical conductivity by applying chalcogenide doping. The films were produced by drop-casting or spin coating, and sulfur was introduced in the precursor solution using bismuth triethylxanthate. The physical-chemical analysis confirms the substitution. The sulfur introduction caused resistivity reduction by 2 orders of magnitude, and the thermal voltage exceeded 40 mV K-1 near 300 K in doped and undoped bismuth-based perovskite derivates. X-ray diffraction, Raman spectroscopy, and grazing-incidence wide-angle X-ray scattering were employed to confirm the structure. X-ray photoelectron spectroscopy, elemental analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were employed to study the composition and morphology of the produced thin films. UV-visible absorbance, photoluminescence, inverse photoemission, and ultraviolet photoelectron spectroscopies have been used to investigate the energy band gap.
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Affiliation(s)
- Vanira Trifiletti
- Department
of Materials Science and L-NESS, University
of Milano-Bicocca, Via
Cozzi 55, I-20125 Milan, Italy
- School
of Engineering and Materials Science, Queen
Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Matteo Massetti
- Laboratory
of Organic Electronics, Department of Science and Technology, Linköping University, Norrköping SE-601
74, Sweden
| | - Alberto Calloni
- Dipartimento
di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano, Italy
| | - Sally Luong
- School
of Engineering and Materials Science, Queen
Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Andrea Pianetti
- Department
of Materials Science and L-NESS, University
of Milano-Bicocca, Via
Cozzi 55, I-20125 Milan, Italy
| | - Silvia Milita
- Institute
for Microelectronics and Microsystems (CNRIMM), Via Piero Gobetti 101, 40129 Bologna, Italy
| | - Bob C. Schroeder
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Gianlorenzo Bussetti
- Dipartimento
di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano, Italy
| | - Simona Binetti
- Department
of Materials Science and L-NESS, University
of Milano-Bicocca, Via
Cozzi 55, I-20125 Milan, Italy
| | - Simone Fabiano
- Laboratory
of Organic Electronics, Department of Science and Technology, Linköping University, Norrköping SE-601
74, Sweden
| | - Oliver Fenwick
- School
of Engineering and Materials Science, Queen
Mary University of London, Mile End Road, London E1 4NS, United Kingdom
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Ruta V, Di Liberto G, Moriggi F, Ivanov YP, Divitini G, Bussetti G, Barbera V, Bajada MA, Galimberti M, Pacchioni G, Vilé G. Copper Single Atoms Chelated on Ligand-Modified Carbon for Ullmann-type C-O Coupling. CHEMSUSCHEM 2024; 17:e202301529. [PMID: 38050778 DOI: 10.1002/cssc.202301529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 12/01/2023] [Accepted: 12/04/2023] [Indexed: 12/06/2023]
Abstract
Cross-coupling reactions are of great importance in chemistry due to their ability to facilitate the construction of complex organic molecules. Among these reactions, the Ullmann-type C-O coupling between phenols and aryl halides is particularly noteworthy and useful for preparing diarylethers. However, this reaction typically relies on homogeneous catalysts that rapidly deactivate under harsh reaction conditions. In this study, we introduce a novel heterogeneous catalyst for the Ullmann-type C-O coupling reaction, comprised of isolated Cu atoms chelated to a tetraethylenepentamine-pyrrole ligand that is immobilized on graphite nanoplatelets. The catalytic study reveals the recyclability of the material, and demonstrates the crucial role of the pyrrole linker in stabilizing the Cu sites. The work expands the potential of single-atom catalyst nanoarchitectures and underscores the significance of ligands in stabilizing metals in cationic forms, providing a novel, tailored catalyst for cross-coupling chemistries.
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Affiliation(s)
- Vincenzo Ruta
- Department of Chemistry, Materials, and Chemical Engineering, "Giulio Natta" Politecnico di Milano, Piazza Leonardo da Vinci 32, IT-20133, Milano, Italy
| | - Giovanni Di Liberto
- Department of Materials Science, Università degli Studi di Milano-Bicocca, Via Roberto Cozzi 55, IT-20125, Milano, Italy
| | - Francesco Moriggi
- Department of Chemistry, Materials, and Chemical Engineering, "Giulio Natta" Politecnico di Milano, Piazza Leonardo da Vinci 32, IT-20133, Milano, Italy
| | - Yurii P Ivanov
- Electron Spectroscopy and Nanoscopy, Italian Institute of Technology, Via Morego 30, IT-16163, Genova, Italy
| | - Giorgio Divitini
- Electron Spectroscopy and Nanoscopy, Italian Institute of Technology, Via Morego 30, IT-16163, Genova, Italy
| | - Gianlorenzo Bussetti
- Department of Physics, Politecnico di Milano, Piazza Leonardo da Vinci 32, IT-20133, Milano, Italy
| | - Vincenzina Barbera
- Department of Chemistry, Materials, and Chemical Engineering, "Giulio Natta" Politecnico di Milano, Piazza Leonardo da Vinci 32, IT-20133, Milano, Italy
| | - Mark A Bajada
- Department of Chemistry, Materials, and Chemical Engineering, "Giulio Natta" Politecnico di Milano, Piazza Leonardo da Vinci 32, IT-20133, Milano, Italy
| | - Maurizio Galimberti
- Department of Chemistry, Materials, and Chemical Engineering, "Giulio Natta" Politecnico di Milano, Piazza Leonardo da Vinci 32, IT-20133, Milano, Italy
| | - Gianfranco Pacchioni
- Department of Materials Science, Università degli Studi di Milano-Bicocca, Via Roberto Cozzi 55, IT-20125, Milano, Italy
| | - Gianvito Vilé
- Department of Chemistry, Materials, and Chemical Engineering, "Giulio Natta" Politecnico di Milano, Piazza Leonardo da Vinci 32, IT-20133, Milano, Italy
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3
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Campos AF, Duret P, Cabaret S, Duden T, Tejeda A. Spin- and angle-resolved inverse photoemission setup with spin orientation independent from electron incidence angle. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:093904. [PMID: 36182468 DOI: 10.1063/5.0076088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 05/21/2022] [Indexed: 06/16/2023]
Abstract
A new spin- and angle-resolved inverse photoemission setup with a low-energy electron source is presented. The spin-polarized electron source, with a compact design, can decouple the spin polarization vector from the electron beam propagation vector, allowing one to explore any spin orientation at any wavevector in angle-resolved inverse photoemission. The beam polarization can be tuned to any preferred direction with a shielded electron optical system, preserving the parallel beam condition. We demonstrate the performances of the setup by measurements on Cu(001) and Au(111). We estimate the energy resolution of the overall system at room temperature to be ∼170 meV from kBTeff of a Cu(001) Fermi level, allowing a direct comparison to photoemission. The spin-resolved operation of the setup has been demonstrated by measuring the Rashba splitting of the Au(111) Shockley surface state. The effective polarization of the electron beam is P = 30% ± 3%, and the wavevector resolution is ΔkF ≲ 0.06 Å-1. Measurements on the Au(111) surface state demonstrate how the electron beam polarization direction can be tuned in the three spatial dimensions. The maximum of the spin asymmetry is reached when the electron beam polarization is aligned with the in-plane spin polarization of the Au(111) surface state.
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Affiliation(s)
- A F Campos
- Laboratoire de Physique des Solides, CNRS, Université Paris-Saclay, 91405 Orsay, France
| | - P Duret
- Laboratoire de Physique des Solides, CNRS, Université Paris-Saclay, 91405 Orsay, France
| | - S Cabaret
- Laboratoire de Physique des Solides, CNRS, Université Paris-Saclay, 91405 Orsay, France
| | - T Duden
- Constructive Solutions for Science and Technology, 33649 Bielefeld, Germany
| | - A Tejeda
- Laboratoire de Physique des Solides, CNRS, Université Paris-Saclay, 91405 Orsay, France
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4
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Albani G, Schio L, Goto F, Calloni A, Orbelli Biroli A, Bossi A, Melone F, Achilli S, Fratesi G, Zucchetti C, Floreano L, Bussetti G. Ordered assembly of non-planar vanadyl-tetraphenylporphyrins on ultra-thin iron oxide. Phys Chem Chem Phys 2022; 24:17077-17087. [PMID: 35792072 DOI: 10.1039/d1cp05914a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Stabilizing ordered assemblies of molecules represents the first step towards the construction of molecular devices featuring hybrid (organic-inorganic) interfaces where molecules can be easily functionalized in view of specific applications. Molecular layers of planar metal-tetraphenylporphyrins (MTPP) grown on an ultrathin iron oxide [namely Fe(001)-p(1 × 1)O] show indeed a high degree of structural order. The generality of such a picture is tested by exploiting non-planar porphyrins, such as vanadyl-TPP (VOTPP). These molecules feature a VO2+ ion in their center, with the O atom protruding out of the plane of the porphyrin ring. In this work, by employing diffraction, photoemission and X-ray absorption, we prove that non-planar VOTPP can nevertheless form a square and ordered superstructure, where porphyrin molecules lie flat with respect to the underlying substrate. Ab initio density functional theory simulations are used to elucidate the VO bond orientation with respect to the iron substrate.
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Affiliation(s)
- Guglielmo Albani
- Dipartimento di Fisica, Politecnico di Milano, p.za Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Luca Schio
- Istituto Officina dei Materiali - CNR-IOM, Laboratorio TASC, s.s. 14 km 163.5, 34149 Trieste, Italy
| | - Francesco Goto
- Dipartimento di Fisica, Politecnico di Milano, p.za Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Alberto Calloni
- Dipartimento di Fisica, Politecnico di Milano, p.za Leonardo da Vinci 32, 20133, Milano, Italy.
| | | | - Alberto Bossi
- Istituto di Scienze e Tecnologie Chimiche "G. Natta" del Consiglio Nazionale delle Ricerche (CNR-SCITEC), PST via G. Fantoli 16/15, 20138 Milano, Italy
| | - Francesco Melone
- ETSF and Dipartimento di Fisica "Aldo Pontremoli", Università degli Studi di Milano, Via Celoria, 16, 20133 Milano, Italy
| | - Simona Achilli
- ETSF and Dipartimento di Fisica "Aldo Pontremoli", Università degli Studi di Milano, Via Celoria, 16, 20133 Milano, Italy
| | - Guido Fratesi
- ETSF and Dipartimento di Fisica "Aldo Pontremoli", Università degli Studi di Milano, Via Celoria, 16, 20133 Milano, Italy
| | - Carlo Zucchetti
- Dipartimento di Fisica, Politecnico di Milano, p.za Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Luca Floreano
- Istituto Officina dei Materiali - CNR-IOM, Laboratorio TASC, s.s. 14 km 163.5, 34149 Trieste, Italy
| | - Gianlorenzo Bussetti
- Dipartimento di Fisica, Politecnico di Milano, p.za Leonardo da Vinci 32, 20133, Milano, Italy.
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5
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Bussetti G, Bernasconi R, Filoni C, Magagnin L, Bossi A, Ciccacci F, Duò L. A stable porphyrin functionalized graphite electrode used at the oxygen evolution reaction potential. ELECTROANAL 2021. [DOI: 10.1002/elan.202100563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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An In-Depth Assessment of the Electronic and Magnetic Properties of a Highly Ordered Hybrid Interface: The Case of Nickel Tetra-Phenyl-Porphyrins on Fe(001)- p(1 × 1)O. MICROMACHINES 2021; 12:mi12020191. [PMID: 33668500 PMCID: PMC7918924 DOI: 10.3390/mi12020191] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 02/08/2021] [Accepted: 02/11/2021] [Indexed: 11/17/2022]
Abstract
In this paper we focus on the structural, electronic, and magnetic properties of Ni tetra-phenyl-porphyrins (NiTPP) grown on top of Fe(001)–p(1 × 1)O. Ordered thin films of metal TPP molecules are potentially interesting for organic electronic and spintronic applications, especially when they are coupled to a ferromagnetic substrate. Unfortunately, porphyrin layers deposited on top of ferromagnetic substrates do not generally show long-range order. In this work, we provide evidence of an ordered disposition of the organic film above the iron surface and we prove that the thin layer of iron oxide decouples the molecules from the substrate, thus preserving the molecular electronic features, especially the HOMO-LUMO gap, even when just a few organic layers are deposited. The effect of the exposure to molecular oxygen is also investigated and an increased robustness against oxidation with respect to the bare substrate is detected. Finally, we present our results for the magnetic analysis performed by spin resolved spectroscopy, finding a null magnetic coupling between the molecules and the substrate.
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Calloni A, Bussetti G, Avvisati G, Jagadeesh MS, Pacilè D, Ferretti A, Varsano D, Cardoso C, Duò L, Ciccacci F, Betti MG. Empty electron states in cobalt-intercalated graphene. J Chem Phys 2020; 153:214703. [PMID: 33291906 DOI: 10.1063/5.0021814] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The dispersion of the electronic states of epitaxial graphene (Gr) depends significantly on the strength of the bonding with the underlying substrate. We report on empty electron states in cobalt-intercalated Gr grown on Ir(111), studied by angle-resolved inverse photoemission spectroscopy and x-ray absorption spectroscopy, complemented with density functional theory calculations. The weakly bonded Gr on Ir preserves the peculiar spectroscopic features of the Gr band structure, and the empty spectral densities are almost unperturbed. Upon intercalation of a Co layer, the electronic response of the interface changes, with an intermixing of the Gr π* bands and Co d states, which breaks the symmetry of π/σ states, and a downshift of the upper part of the Gr Dirac cone. Similarly, the image potential of Ir(111) is unaltered by the Gr layer, while a downward shift is induced upon Co intercalation, as unveiled by the image state energy dispersion mapped in a large region of the surface Brillouin zone.
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Affiliation(s)
- Alberto Calloni
- Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Gianlorenzo Bussetti
- Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Giulia Avvisati
- Dipartimento di Fisica, Università di Roma "La Sapienza", I-00185 Roma, Italy
| | - Madan S Jagadeesh
- Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Daniela Pacilè
- Dipartimento di Fisica, Università della Calabria, I-87036 Arcavacata di Rende (Cs), Italy
| | | | | | | | - Lamberto Duò
- Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Franco Ciccacci
- Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Maria Grazia Betti
- Dipartimento di Fisica, Università di Roma "La Sapienza", I-00185 Roma, Italy
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Ni-Doped Titanium Dioxide Films Obtained by Plasma Electrolytic Oxidation in Refrigerated Electrolytes. SURFACES 2020. [DOI: 10.3390/surfaces3020013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Porous crystalline Ni-doped TiO2 films were produced using DC plasma electrolytic oxidation in refrigerated H2SO4 aqueous solutions containing NiSO4. The crystalline phase structure consisted of a mixture of anatase and rutile, ranging from ~30 to ~80 wt % rutile. The oxide films obtained at low NiSO4 concentration showed the highest photocurrent values under monochromatic irradiation in the UV-vis range, outperforming pure TiO2. By increasing NiSO4 concentration above a threshold value, the photoelectrochemical activity of the films decreased below that of undoped TiO2. Similar results were obtained using cyclic voltammetry upon polychromatic UV-vis irradiation. Glow discharge optical emission spectrometry (GD-OES) analysis evidenced a sulfur signal peaking at the TiO2/Ti interface. XPS spectra revealed that oxidized Ni2+, S4+ and S6+ ions were included in the oxide films. In agreement with photocurrent measurements, photoluminescence (PL) spectra confirmed that less intense PL emission, i.e., a lower electron-hole recombination rate, was observed for Ni-doped samples, though overdoping was detrimental.
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9
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Abstract
In this study, we report an investigation of the photoelectrochemical activity of TiO2 films formed by DC plasma electrolytic oxidation (PEO) at a variable potential in a sulfuric acid electrolyte at 0 and 25 °C. The surface morphology was mainly determined by the oxide-forming potential. X-Ray Diffraction and Raman analyses showed that the relative amount of the anatase and rutile phases varied from 100% anatase at low potential (110–130 V) to 100% rutile at high potential (180–200 V), while mixed-phase oxide films formed at intermediate potential. Correspondingly, the band gap of the TiO2 films decreased from about 3.20 eV (pure anatase) to 2.94 eV (pure rutile) and was red-shifted about 0.1 eV by reducing the electrolyte temperature from 25 °C to 0 °C. Glow-Discharge Optical Emission Spectroscopy (GD-OES) and X-ray Photoelectron Spectroscopy (XPS) analyses evidenced S-containing species located preferentially close to the TiO2/Ti interface. The photoelectrochemical activity was assessed by measuring the incident photon-to-current efficiency (IPCE) under Ultraviolet C (UV-C) irradiation, which showed a non-gaussian normal trend as a function of the PEO cell potential, with maximum values exceeding 80%. Photoelectrocatalytic activity was assessed by decolorization of model solutions containing methylene blue. Photoanodes having higher IPCE values showed faster decolorization kinetics.
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10
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Calloni A, Jagadeesh MS, Albani G, Goletti C, Duò L, Ciccacci F, Bussetti G. Ordered assembling of Co tetra phenyl porphyrin on oxygen-passivated Fe(001): from single to multilayer films. EPJ WEB OF CONFERENCES 2020. [DOI: 10.1051/epjconf/202023000014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Tetra-phenyl prophyrins (TPP) are an interesting class of organic molecules characterized by a ring structure with a metal ion in their centre. An ordered growth of such molecules can be obtained even on metallic substrates by means of a proper modification of the reactive interface, as we demonstrated for ZnTPP molecules coupled to oxygen-passivated Fe(001) [G. Bussetti et al. Appl. Surf. Sci. 390, 856 (2016)]. More recently, we focused on CoTPP molecules, characterized by a not nil magnetic moment and therefore of potential interest for magnetic applications. As in the ZnTPP case, our results for one monolayer coverage report the formation of an ordered assembly of flat-lying molecules. However, some differences between the two molecular species are observed in the packing scheme and in the degree of electronic interaction with the substrate. With the aim of reaching, also for CoTPP, a comprehensive view of molecular organization on Fe, we complement here our previous investigations by following the growth of the CoTPP film for increasing coverage, showing that an ordered stacking of such molecules is indeed realized at least up to four molecular layers.
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11
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Lodesani A, Picone A, Brambilla A, Giannotti D, Jagadeesh MS, Calloni A, Bussetti G, Berti G, Zani M, Finazzi M, Duò L, Ciccacci F. Graphene as an Ideal Buffer Layer for the Growth of High-Quality Ultrathin Cr 2O 3 Layers on Ni(111). ACS NANO 2019; 13:4361-4367. [PMID: 30943012 DOI: 10.1021/acsnano.8b09588] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Metal-oxide nanostructures play a fundamental role in a large number of technological applications, ranging from chemical sensors to data storage devices. As the size of the devices shrinks down to the nanoscale, it is mandatory to obtain sharp and good quality interfaces. Here, it is shown that a two-dimensional material, namely, graphene, can be exploited as an ideal buffer layer to tailor the properties of the interface between a metallic substrate and an ultrathin oxide. This is proven at the interface between an ultrathin film of the magnetoelectric antiferromagnetic oxide Cr2O3 and a Ni(111) single crystal substrate. The chemical composition of the samples has been studied by means of X-ray photoemission spectroscopy, showing that the insertion of graphene, which remains buried at the interface, is able to prevent the oxidation of the substrate. This protective action leads to an ordered and layer-by-layer growth, as revealed by scanning tunneling microscopy data. The structural analysis performed by low-energy electron diffraction indicates that the oxide layer grown on graphene experiences a significant compressive strain, which strongly influences the surface electronic structure observed by scanning tunneling spectroscopy.
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Affiliation(s)
| | - Andrea Picone
- Department of Physics , Politecnico di Milano , Milano 20133 , Italy
| | - Alberto Brambilla
- Department of Physics , Politecnico di Milano , Milano 20133 , Italy
| | - Dario Giannotti
- Department of Physics , Politecnico di Milano , Milano 20133 , Italy
| | - Madan S Jagadeesh
- Department of Physics , Politecnico di Milano , Milano 20133 , Italy
| | - Alberto Calloni
- Department of Physics , Politecnico di Milano , Milano 20133 , Italy
| | | | - Giulia Berti
- Department of Physics , Politecnico di Milano , Milano 20133 , Italy
| | - Maurizio Zani
- Department of Physics , Politecnico di Milano , Milano 20133 , Italy
| | - Marco Finazzi
- Department of Physics , Politecnico di Milano , Milano 20133 , Italy
| | - Lamberto Duò
- Department of Physics , Politecnico di Milano , Milano 20133 , Italy
| | - Franco Ciccacci
- Department of Physics , Politecnico di Milano , Milano 20133 , Italy
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12
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Calloni A, Cozzi M, Jagadeesh MS, Bussetti G, Ciccacci F, Duò L. Magnetic behavior of metastable Fe films grown on Ir(1 1 1). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:015001. [PMID: 29186003 DOI: 10.1088/1361-648x/aa99c3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We investigated the growth of ultra-thin Fe films on Ir(1 1 1) by means of in situ low energy electron diffraction and spin-resolved photoemission techniques. We observe a (1 × 1) diffraction pattern, characteristic of the fcc substrate, below four monolayers (ML). Then, a complex superstructure starts to develop, compatible with the formation of bcc-like Fe domains aligned with the substrate according to the Kourdjumov-Sachs orientation relationships. The analysis of the diffraction patterns reveals a progressive evolution towards a fully relaxed bcc lattice, characteristic of bulk Fe. Both photoemission (filled states) and inverse photoemission (empty states) results show characteristic features related to the contribution of the Fe layer, evolving towards those observed on the Fe (1 1 0) bcc surface. Spin resolution allows to detect a spectral polarization above 4 ML, corresponding to the formation of bcc Fe, which gradually increases indicating the formation of an in-plane magnetized ferromagnetic layer in thick films. No in-plane net magnetization is detected in thinner films, independent of the sample temperature down to 30 K. Following recent investigations on the Fe/Ir(1 1 1) system with microscopy techniques, we link this observation to the stabilization of a non collinear spin structure yielding an overall nil magnetization.
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Affiliation(s)
- Alberto Calloni
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano, Italy
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13
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Brambilla A, Picone A, Giannotti D, Calloni A, Berti G, Bussetti G, Achilli S, Fratesi G, Trioni MI, Vinai G, Torelli P, Panaccione G, Duò L, Finazzi M, Ciccacci F. Enhanced Magnetic Hybridization of a Spinterface through Insertion of a Two-Dimensional Magnetic Oxide Layer. NANO LETTERS 2017; 17:7440-7446. [PMID: 29149565 DOI: 10.1021/acs.nanolett.7b03314] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Interfaces between organic semiconductors and ferromagnetic metals offer intriguing opportunities in the rapidly developing field of organic spintronics. Understanding and controlling the spin-polarized electronic states at the interface is the key toward a reliable exploitation of this kind of systems. Here we propose an approach consisting in the insertion of a two-dimensional magnetic oxide layer at the interface with the aim of both increasing the reproducibility of the interface preparation and offering a way for a further fine control over the electronic and magnetic properties. We have inserted a two-dimensional Cr4O5 layer at the C60/Fe(001) interface and have characterized the corresponding morphological, electronic, and magnetic properties. Scanning tunneling microscopy and electron diffraction show that the film grows well-ordered both in the monolayer and multilayer regimes. Electron spectroscopies confirm that hybridization of the electronic states occurs at the interface. Finally, magnetic dichroism in X-ray absorption shows an unprecedented spin-polarization of the hybridized fullerene states. The latter result is discussed also in light of an ab initio theoretical analysis.
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Affiliation(s)
- Alberto Brambilla
- Dipartimento di Fisica, Politecnico di Milano , piazza Leonardo da Vinci, 32, 20133 Milano, Italy
| | - Andrea Picone
- Dipartimento di Fisica, Politecnico di Milano , piazza Leonardo da Vinci, 32, 20133 Milano, Italy
| | - Dario Giannotti
- Dipartimento di Fisica, Politecnico di Milano , piazza Leonardo da Vinci, 32, 20133 Milano, Italy
| | - Alberto Calloni
- Dipartimento di Fisica, Politecnico di Milano , piazza Leonardo da Vinci, 32, 20133 Milano, Italy
| | - Giulia Berti
- Dipartimento di Fisica, Politecnico di Milano , piazza Leonardo da Vinci, 32, 20133 Milano, Italy
| | - Gianlorenzo Bussetti
- Dipartimento di Fisica, Politecnico di Milano , piazza Leonardo da Vinci, 32, 20133 Milano, Italy
| | - Simona Achilli
- Dipartimento di Fisica, Università degli Studi di Milano , Via Celoria, 16, 20133 Milano, Italy
| | - Guido Fratesi
- Dipartimento di Fisica, Università degli Studi di Milano , Via Celoria, 16, 20133 Milano, Italy
| | - Mario I Trioni
- CNR - National Research Council of Italy, ISTM , via Golgi 19, 20133 Milano, Italy
| | - Giovanni Vinai
- Laboratorio TASC, IOM-CNR , S.S. 14 km 163.5, Basovizza, I, 34149 Trieste, Italy
| | - Piero Torelli
- Laboratorio TASC, IOM-CNR , S.S. 14 km 163.5, Basovizza, I, 34149 Trieste, Italy
| | - Giancarlo Panaccione
- Laboratorio TASC, IOM-CNR , S.S. 14 km 163.5, Basovizza, I, 34149 Trieste, Italy
| | - Lamberto Duò
- Dipartimento di Fisica, Politecnico di Milano , piazza Leonardo da Vinci, 32, 20133 Milano, Italy
| | - Marco Finazzi
- Dipartimento di Fisica, Politecnico di Milano , piazza Leonardo da Vinci, 32, 20133 Milano, Italy
| | - Franco Ciccacci
- Dipartimento di Fisica, Politecnico di Milano , piazza Leonardo da Vinci, 32, 20133 Milano, Italy
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14
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Beretta D, Barker AJ, Maqueira-Albo I, Calloni A, Bussetti G, Dell'Erba G, Luzio A, Duò L, Petrozza A, Lanzani G, Caironi M. Thermoelectric Properties of Highly Conductive Poly(3,4-ethylenedioxythiophene) Polystyrene Sulfonate Printed Thin Films. ACS APPLIED MATERIALS & INTERFACES 2017; 9:18151-18160. [PMID: 28466635 DOI: 10.1021/acsami.7b04533] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Organic conductors are being evaluated for potential use in waste heat recovery through lightweight and flexible thermoelectric generators manufactured using cost-effective printing processes. Assessment of the potentiality of organic materials in real devices still requires a deeper understanding of the physics behind their thermoelectric properties, which can pave the way toward further development of the field. This article reports a detailed thermoelectric study of a set of highly conducting inkjet-printed films of commercially available poly(3,4-ethylenedioxythiophene) polystyrene sulfonate formulations characterized by in-plane electrical conductivity, spanning the interval 10-500 S/cm. The power factor is maximized for the formulation showing an intermediate electrical conductivity. The Seebeck coefficient is studied in the framework of Mott's relation, assuming a (semi-)classical definition of the transport function. Ultraviolet photoelectron spectroscopy at the Fermi level clearly indicates that the shape of the density of states alone is not sufficient to explain the observed Seebeck coefficient, suggesting that carrier mobility is important in determining both the electrical conductivity and thermopower. Finally, the cross-plane thermal conductivity is reliably extracted thanks to a scaling approach that can be easily performed using typical pump-probe spectroscopy.
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Affiliation(s)
- Davide Beretta
- Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia , via Pascoli 70/3, 20133 Milano (MI), Italy
- Dipartimento di Fisica, Politecnico di Milano , P.zza Leonardo da Vinci 32, 20133 Milano (MI), Italy
| | - Alex J Barker
- Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia , via Pascoli 70/3, 20133 Milano (MI), Italy
| | - Isis Maqueira-Albo
- Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia , via Pascoli 70/3, 20133 Milano (MI), Italy
- Dipartimento di Fisica, Politecnico di Milano , P.zza Leonardo da Vinci 32, 20133 Milano (MI), Italy
| | - Alberto Calloni
- Dipartimento di Fisica, Politecnico di Milano , P.zza Leonardo da Vinci 32, 20133 Milano (MI), Italy
| | - Gianlorenzo Bussetti
- Dipartimento di Fisica, Politecnico di Milano , P.zza Leonardo da Vinci 32, 20133 Milano (MI), Italy
| | - Giorgio Dell'Erba
- Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia , via Pascoli 70/3, 20133 Milano (MI), Italy
| | - Alessandro Luzio
- Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia , via Pascoli 70/3, 20133 Milano (MI), Italy
| | - Lamberto Duò
- Dipartimento di Fisica, Politecnico di Milano , P.zza Leonardo da Vinci 32, 20133 Milano (MI), Italy
| | - Annamaria Petrozza
- Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia , via Pascoli 70/3, 20133 Milano (MI), Italy
| | - Guglielmo Lanzani
- Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia , via Pascoli 70/3, 20133 Milano (MI), Italy
- Dipartimento di Fisica, Politecnico di Milano , P.zza Leonardo da Vinci 32, 20133 Milano (MI), Italy
| | - Mario Caironi
- Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia , via Pascoli 70/3, 20133 Milano (MI), Italy
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15
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Bussetti G, Calloni A, Yivlialin R, Picone A, Bottegoni F, Finazzi M. Filled and empty states of Zn-TPP films deposited on Fe(001)- p(1×1)O. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2016; 7:1527-1531. [PMID: 28144503 PMCID: PMC5238660 DOI: 10.3762/bjnano.7.146] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 10/14/2016] [Indexed: 06/06/2023]
Abstract
Zn-tetraphenylporphyrin (Zn-TPP) was deposited on a single layer of metal oxide, namely an Fe(001)-p(1×1)O surface. The filled and empty electronic states were measured by means of UV photoemission and inverse photoemission spectroscopy on a single monolayer and a 20 monolayer thick film. The ionization energy and the electron affinity of the organic film were deduced and the interface dipole was determined and compared with data available in the literature.
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Affiliation(s)
- Gianlorenzo Bussetti
- Department of Physics, Politecnico di Milano, p.za Leonardo da Vinci 32, 20133 Milano, Italy
| | - Alberto Calloni
- Department of Physics, Politecnico di Milano, p.za Leonardo da Vinci 32, 20133 Milano, Italy
| | - Rossella Yivlialin
- Department of Physics, Politecnico di Milano, p.za Leonardo da Vinci 32, 20133 Milano, Italy
| | - Andrea Picone
- Department of Physics, Politecnico di Milano, p.za Leonardo da Vinci 32, 20133 Milano, Italy
| | - Federico Bottegoni
- Department of Physics, Politecnico di Milano, p.za Leonardo da Vinci 32, 20133 Milano, Italy
| | - Marco Finazzi
- Department of Physics, Politecnico di Milano, p.za Leonardo da Vinci 32, 20133 Milano, Italy
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16
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Picone A, Giannotti D, Riva M, Calloni A, Bussetti G, Berti G, Duò L, Ciccacci F, Finazzi M, Brambilla A. Controlling the Electronic and Structural Coupling of C 60 Nano Films on Fe(001) through Oxygen Adsorption at the Interface. ACS APPLIED MATERIALS & INTERFACES 2016; 8:26418-26424. [PMID: 27603203 DOI: 10.1021/acsami.6b09641] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
C60 molecules coupled to metals form hybrid systems exploited in a broad range of emerging fields, such as nanoelectronics, spintronics, and photovoltaic solar cells. The electronic coupling at the C60/metal interface plays a crucial role in determining the charge and spin transport in C60-based devices; therefore, a detailed understanding of the interface electronic structure is a prerequisite to engineering the device functionalities. Here, we compare the electronic and structural properties of C60 monolayers interfaced with Fe(001) and oxygen-passivated Fe(001)-p(1 × 1)O substrates. By combining scanning tunneling microscopy and spectroscopy, Auger electron spectroscopy, photoemission and inverse photoemission spectroscopies, we are able to elucidate the striking effect of oxygen on the interaction between Fe(001) and C60. Upon C60 deposition on the oxygen-passivated surface, the oxygen layer remains buried at the C60/Fe(001)-p(1 × 1)O interface, efficiently decoupling the fullerene film from the metallic substrate. Tunneling and photoemission spectroscopies reveal the presence of well-defined molecular resonances for the C60/Fe(001)-p(1 × 1)O system, with a large HOMO-LUMO gap of about 3.4 eV. On the other hand, for the C60/Fe(001) interface, a strong hybridization between the substrate states and the C60 orbitals occurs, resulting in broader molecular resonances.
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Affiliation(s)
- Andrea Picone
- Dipartimento di Fisica, Politecnico di Milano , Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Dario Giannotti
- Dipartimento di Fisica, Politecnico di Milano , Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Michele Riva
- Institute of Applied Physics, TU-Wien , Wiedner Hauptstraße 8-10, 1040 Vienna, Austria
| | - Alberto Calloni
- Dipartimento di Fisica, Politecnico di Milano , Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Gianlorenzo Bussetti
- Dipartimento di Fisica, Politecnico di Milano , Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Giulia Berti
- Dipartimento di Fisica, Politecnico di Milano , Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Lamberto Duò
- Dipartimento di Fisica, Politecnico di Milano , Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Franco Ciccacci
- Dipartimento di Fisica, Politecnico di Milano , Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Marco Finazzi
- Dipartimento di Fisica, Politecnico di Milano , Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Alberto Brambilla
- Dipartimento di Fisica, Politecnico di Milano , Piazza Leonardo da Vinci 32, 20133 Milano, Italy
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17
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Aluicio-Sarduy E, Singh R, Kan Z, Ye T, Baidak A, Calloni A, Berti G, Duò L, Iosifidis A, Beaupré S, Leclerc M, Butt HJ, Floudas G, Keivanidis PE. Elucidating the impact of molecular packing and device architecture on the performance of nanostructured perylene diimide solar cells. ACS APPLIED MATERIALS & INTERFACES 2015; 7:8687-8698. [PMID: 25822414 DOI: 10.1021/acsami.5b00827] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
UNLABELLED The performance of organic photovoltaic devices (OPV) with nanostructured polymer:perylene diimide (PDI) photoactive layers approaches the levels of the corresponding polymer:fullerene systems. Nevertheless, a coherent understanding of the difficulty for PDI-based OPV devices to deliver high power conversion efficiencies remains elusive. Here we perform a comparative study of a set of four different polymer:PDI OPV model systems. The different device performances observed are attributed to differences in the nanostructural motif of these composites, as determined by wide-angle X-ray scattering (WAXS) measurements. Long-range structural order in the PDI domain dictates (i) the stabilization energy and (ii) the concentration of the PDI excimers in the composites. The quenching of the PDI excimer photoluminescence (PL) is found to be insensitive to the former, but it depends on the latter. High PL quenching occurs for the low concentration of PDI excimers that are formed in PDI columns with a length comparable to the PDI excimer diffusion length. The stabilization of the PDI excimer state increases as the long-range order in the PDI domains improves. The structural order of the PDI domains primarily affects charge transport. Electron mobility reduces as the size of the PDI domain increases, suggesting that well-ordered PDI domains suffer from poor electronic connectivity. WAXS further reveals the presence of additional intermolecular PDI interactions, other than the direct face-to-face intermolecular coupling, that introduce a substantial energetic disorder in the polymer:PDI composites. Conventional device architectures with hole-collecting ITO/PEDOT:PSS bottom electrodes are compared with inverted device architectures bearing bottom electron-collecting electrodes of ITO/ZnO. In all cases the ZnO-functionalized devices surpass the performance of the conventional device analogues. X-ray photoelectron spectroscopy explains that in PEDOT PSS-functionalized devices, the PDI component preferentially segregates closer to the hydrophilic PEDOT PSS electrode, thus impeding the efficient charge extraction and limiting device photocurrent.
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Affiliation(s)
- Eduardo Aluicio-Sarduy
- †Fondazione Istituto Italiano di Tecnologia, Centre for Nanoscience and Technology@PoliMi, Via Giovanni Pascoli 70/3, 20133 Milano, Italy
| | - Ranbir Singh
- †Fondazione Istituto Italiano di Tecnologia, Centre for Nanoscience and Technology@PoliMi, Via Giovanni Pascoli 70/3, 20133 Milano, Italy
| | - Zhipeng Kan
- †Fondazione Istituto Italiano di Tecnologia, Centre for Nanoscience and Technology@PoliMi, Via Giovanni Pascoli 70/3, 20133 Milano, Italy
| | - Tengling Ye
- †Fondazione Istituto Italiano di Tecnologia, Centre for Nanoscience and Technology@PoliMi, Via Giovanni Pascoli 70/3, 20133 Milano, Italy
| | - Aliaksandr Baidak
- †Fondazione Istituto Italiano di Tecnologia, Centre for Nanoscience and Technology@PoliMi, Via Giovanni Pascoli 70/3, 20133 Milano, Italy
| | - Alberto Calloni
- ‡Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133, Milano, Italy
| | - Giulia Berti
- ‡Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133, Milano, Italy
| | - Lamberto Duò
- ‡Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133, Milano, Italy
| | | | - Serge Beaupré
- §Département de Chimie, Université Laval, Pavillon A-Vachon 1045, Avenue de la Médecine, Québec City, Québec, Canada G1 V 0A6
| | - Mario Leclerc
- §Département de Chimie, Université Laval, Pavillon A-Vachon 1045, Avenue de la Médecine, Québec City, Québec, Canada G1 V 0A6
| | - Hans-Jürgen Butt
- ∥Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128, Mainz, Germany
| | - George Floudas
- ⊥University of Ioannina, Department of Physics, 451 10 Ioannina, Greece
| | - Panagiotis E Keivanidis
- #Cyprus University of Technology, Department of Mechanical Engineering and Materials Science and Engineering, Dorothea Bldg 511, 45 Kitiou Kyprianou Street, 3041 Limassol, Cyprus
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