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Koutsouflakis E, Krylov D, Bachellier N, Sostina D, Dubrovin V, Liu F, Spree L, Velkos G, Schimmel S, Wang Y, Büchner B, Westerström R, Bulbucan C, Kirkpatrick K, Muntwiler M, Dreiser J, Greber T, Avdoshenko SM, Dorn H, Popov AA. Metamagnetic transition and a loss of magnetic hysteresis caused by electron trapping in monolayers of single-molecule magnet Tb 2@C 79N. NANOSCALE 2022; 14:9877-9892. [PMID: 35781298 DOI: 10.1039/d1nr08475e] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Realization of stable spin states in surface-supported magnetic molecules is crucial for their applications in molecular spintronics, memory storage or quantum information processing. In this work, we studied the surface magnetism of dimetallo-azafullerene Tb2@C79N, showing a broad magnetic hysteresis in a bulk form. Surprisingly, monolayers of Tb2@C79N exhibited a completely different behavior, with the prevalence of a ground state with antiferromagnetic coupling at low magnetic field and a metamagnetic transition in the magnetic field of 2.5-4 T. Monolayers of Tb2@C79N were deposited onto Cu(111) and Au(111) by evaporation in ultra-high vacuum conditions, and their topography and electronic structure were characterized by scanning tunneling microscopy and spectroscopy (STM/STS). X-ray photoelectron spectroscopy (XPS), in combination with DFT studies, revealed that the nitrogen atom of the azafullerene cage tends to avoid metallic surfaces. Magnetic properties of the (sub)monolayers were then studied by X-ray magnetic circular dichroism (XMCD) at the Tb-M4,5 absorption edge. While in bulk powder samples Tb2@C79N behaves as a single-molecule magnet with ferromagnetically coupled magnetic moments and blocking of magnetization at 28 K, its monolayers exhibited a different ground state with antiferromagnetic coupling of Tb magnetic moments. To understand if this unexpected behavior is caused by a strong hybridization of fullerenes with metallic substrates, XMCD measurements were also performed for Tb2@C79N adsorbed on h-BN|Rh(111) and MgO|Ag(100). The co-existence of two forms of Tb2@C79N was found on these substrates as well, but magnetization curves showed narrow magnetic hysteresis detectable up to 25 K. The non-magnetic state of Tb2@C79N in monolayers is assigned to anionic Tb2@C79N- species with doubly-occupied Tb-Tb bonding orbital and antiferromagnetic coupling of the Tb moments. A charge transfer from the substrate or trapping of secondary electrons are discussed as a plausible origin of these species.
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Affiliation(s)
- Emmanouil Koutsouflakis
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Denis Krylov
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Nicolas Bachellier
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Daria Sostina
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Vasilii Dubrovin
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Fupin Liu
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Lukas Spree
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Georgios Velkos
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Sebastian Schimmel
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Yaofeng Wang
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Bernd Büchner
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Rasmus Westerström
- The Division of Synchrotron Radiation Research, Lund University, SE-22100 Lund, Sweden
- NanoLund, Lund University, Box 118, 22100 Lund, Sweden
| | - Claudiu Bulbucan
- The Division of Synchrotron Radiation Research, Lund University, SE-22100 Lund, Sweden
- NanoLund, Lund University, Box 118, 22100 Lund, Sweden
| | - Kyle Kirkpatrick
- Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Matthias Muntwiler
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Jan Dreiser
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Thomas Greber
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Physik-Institut der Universität Zürich, Winterthurerstr. 190, CH-8057 Zürich, Switzerland
| | - Stas M Avdoshenko
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Harry Dorn
- Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Alexey A Popov
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany.
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2
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Wang Z, Tao M, Yang D, Li Z, Shi M, Sun K, Yang J, Wang J. Strain-Relief Patterns and Kagome Lattice in Self-Assembled C 60 Thin Films Grown on Cd(0001). Int J Mol Sci 2021; 22:ijms22136880. [PMID: 34206862 PMCID: PMC8268109 DOI: 10.3390/ijms22136880] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 06/18/2021] [Accepted: 06/20/2021] [Indexed: 12/15/2022] Open
Abstract
We report an ultra-high vacuum low-temperature scanning tunneling microscopy (STM) study of the C60 monolayer grown on Cd(0001). Individual C60 molecules adsorbed on Cd(0001) may exhibit a bright or dim contrast in STM images. When deposited at low temperatures close to 100 K, C60 thin films present a curved structure to release strain due to dominant molecule–substrate interactions. Moreover, edge dislocation appears when two different wavy structures encounter each other, which has seldomly been observed in molecular self-assembly. When growth temperature rose, we found two forms of symmetric kagome lattice superstructures, 2 × 2 and 4 × 4, at room temperature (RT) and 310 K, respectively. The results provide new insight into the growth behavior of C60 films.
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3
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Mihalyuk AN, Utas TV, Eremeev SV, Hsing CR, Wei CM, Zotov AV, Saranin AA. Structural and electronic properties of C 60 fullerene network self-assembled on metal-covered semiconductor surfaces. J Chem Phys 2021; 154:104703. [PMID: 33722044 DOI: 10.1063/5.0040483] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using first-principles density functional theory calculations, we made an accurate structural characterization of the C60 superstructures self-assembled on the Tl-adsorbed Si(111) and Ge(111) surfaces, which finds a good agreement with the recent scanning tunneling microscopy observations. Our band structure calculations revealed the semi-metallic character of the C60/Tl/Si(111) system, while the C60/Tl/Ge(111) system was found to show up the pronounced metallic character due to the cascade of the flat bands lying in the vicinity of the Fermi level. The latter is a fingerprint for strong correlation effects in the C60/Tl/Ge(111) system, which makes it a promising object for studying electrical transport phenomena and opens the prospects for its application in the molecular-based electronic devices. We elucidated the details of the molecule-substrate and intermolecular interactions and discussed the character of a charge transfer in both systems.
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Affiliation(s)
- A N Mihalyuk
- School of Natural Sciences, Far Eastern Federal University, 690922 Vladivostok, Russia
| | - T V Utas
- Institute of Automation and Control Processes, FEB RAS, 690041 Vladivostok, Russia
| | - S V Eremeev
- Institute of Strength Physics and Materials Science, Tomsk 634055, Russia
| | - C R Hsing
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - C M Wei
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - A V Zotov
- Institute of Automation and Control Processes, FEB RAS, 690041 Vladivostok, Russia
| | - A A Saranin
- Institute of Automation and Control Processes, FEB RAS, 690041 Vladivostok, Russia
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4
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Wang YR, Tao ML, Chao-Ke M, Wang ZL, Yang DX, Shi MX, Sun K, Yang JY, Wang JZ. Structure transition of a C 60 monolayer on the Bi(111) surface. RSC Adv 2021; 11:14148-14153. [PMID: 35423925 PMCID: PMC8697672 DOI: 10.1039/d1ra00900a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 03/31/2021] [Indexed: 12/02/2022] Open
Abstract
The interfacial structures of C60 molecules adsorbed on solid surfaces are essential for a wide range of scientific and technological processes in carbon-based nanodevices. Here, we report structural transitions of the C60 monolayer on the Bi(111) surface studied via low-temperature scanning tunneling microscopy (STM). With an increase in temperature, the structure of the C60 monolayer transforms from local-order structures to a (√93 × √93) R20° superstructure, and then to a (11 × 11) R0° superstructure. Moreover, the individual C60 molecules in different superstructures have different orientations. C60 molecules adopt the 6 : 6 C–C bond and 5 : 6 C–C bond facing-up, mixed orientations, and hexagon facing-up in the local-order structure, (√93 × √93) R20°, and (11 × 11) R0° superstructure, respectively. These results shed important light on the growth mechanism of C60 molecules on solid surfaces. With the increase in temperature, the structure of the C60 monolayer on the Bi(111) substrate transforms from local-order structures to a (√93 × √93) R20° superstructure, and then to a (11 × 11) R0° superstructure.![]()
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Affiliation(s)
- Ya-Ru Wang
- School of Physical Science and Technology
- Southwest University
- Chongqing
- China
| | - Min-Long Tao
- School of Physical Science and Technology
- Southwest University
- Chongqing
- China
| | - Ma Chao-Ke
- School of Physical Science and Technology
- Southwest University
- Chongqing
- China
| | - Zi-Long Wang
- School of Physical Science and Technology
- Southwest University
- Chongqing
- China
| | - Da-Xiao Yang
- School of Physical Science and Technology
- Southwest University
- Chongqing
- China
| | - Ming-Xia Shi
- School of Physical Science and Technology
- Southwest University
- Chongqing
- China
| | - Kai Sun
- School of Physical Science and Technology
- Southwest University
- Chongqing
- China
| | - Ji-Yong Yang
- School of Physical Science and Technology
- Southwest University
- Chongqing
- China
| | - Jun-Zhong Wang
- School of Physical Science and Technology
- Southwest University
- Chongqing
- China
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5
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Guo H, Martínez-Galera AJ, Gómez-Rodríguez JM. C 60 self-orientation on hexagonal boron nitride induced by intermolecular coupling. NANOTECHNOLOGY 2020; 32:025711. [PMID: 33073772 DOI: 10.1088/1361-6528/abbbb2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A deep grasp of the properties of the interface between organic molecules and hexagonal boron nitride (h-BN) is essential for the full implementation of these two building blocks in the next generation of electronic devices. Here, using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS), we report on the geometric and electronic features of C60 evaporated on a single layer of h-BN grown on a Rh(110) surface under ultra-high vacuum. Two different molecular assemblies of C60 on the h-BN/Rh(110) surface were observed. The first STM study at room temperature (RT) and at low temperatures (40 K) looked at the molecular orientation of C60 on a two-dimensional layered material. Intramolecular-resolution images demonstrate the existence of a phase transition of C60 over the h-BN/Rh(110) surface similar to that found on bulk solid C60. At RT molecules exhibit random orientations, while at 40 K such rotational disorder vanishes and they adopt a common orientation over the h-BN/Rh(110) surface. The decrease in thermal energy allows recognition between C60 molecules, and they become equally oriented in the configuration at which the van der Waals intermolecular interactions are optimized. Bias-dependent submolecular features obtained by means of high-resolution STM images are interpreted as the highest occupied and lowest unoccupied molecular orbitals. STS data showed that fullerenes are electronically decoupled from the substrate, with a negligible charge transfer effect if any. Finally, the very early stages of multilayer growth were also investigated.
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Affiliation(s)
- Haojie Guo
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid E-28049, Spain
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6
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Puente Santiago AR, Fernandez‐Delgado O, Gomez A, Ahsan MA, Echegoyen L. Fullerenes as Key Components for Low‐Dimensional (Photo)electrocatalytic Nanohybrid Materials. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202009449] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Alain R. Puente Santiago
- Department of Chemistry and Biochemistry University of Texas at El Paso 500 West University Avenue El Paso Texas 79968 USA
| | - Olivia Fernandez‐Delgado
- Department of Chemistry and Biochemistry University of Texas at El Paso 500 West University Avenue El Paso Texas 79968 USA
| | - Ashley Gomez
- Department of Chemistry and Biochemistry University of Texas at El Paso 500 West University Avenue El Paso Texas 79968 USA
| | - Md Ariful Ahsan
- Department of Chemistry and Biochemistry University of Texas at El Paso 500 West University Avenue El Paso Texas 79968 USA
| | - Luis Echegoyen
- Department of Chemistry and Biochemistry University of Texas at El Paso 500 West University Avenue El Paso Texas 79968 USA
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7
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Puente Santiago AR, Fernandez‐Delgado O, Gomez A, Ahsan MA, Echegoyen L. Fullerenes as Key Components for Low‐Dimensional (Photo)electrocatalytic Nanohybrid Materials. Angew Chem Int Ed Engl 2020; 60:122-141. [PMID: 33090642 DOI: 10.1002/anie.202009449] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Indexed: 12/20/2022]
Affiliation(s)
- Alain R. Puente Santiago
- Department of Chemistry and Biochemistry University of Texas at El Paso 500 West University Avenue El Paso Texas 79968 USA
| | - Olivia Fernandez‐Delgado
- Department of Chemistry and Biochemistry University of Texas at El Paso 500 West University Avenue El Paso Texas 79968 USA
| | - Ashley Gomez
- Department of Chemistry and Biochemistry University of Texas at El Paso 500 West University Avenue El Paso Texas 79968 USA
| | - Md Ariful Ahsan
- Department of Chemistry and Biochemistry University of Texas at El Paso 500 West University Avenue El Paso Texas 79968 USA
| | - Luis Echegoyen
- Department of Chemistry and Biochemistry University of Texas at El Paso 500 West University Avenue El Paso Texas 79968 USA
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8
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Shang Y, Wang Z, Yang D, Wang Y, Ma C, Tao M, Sun K, Yang J, Wang J. Orientation Ordering and Chiral Superstructures in Fullerene Monolayer on Cd (0001). NANOMATERIALS 2020; 10:nano10071305. [PMID: 32635309 PMCID: PMC7407170 DOI: 10.3390/nano10071305] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/21/2020] [Accepted: 06/30/2020] [Indexed: 12/11/2022]
Abstract
The structure of C60 thin films grown on Cd (0001) surface has been investigated from submonolayer to second monolayer regimes with a low-temperature scanning tunneling microscopy (STM). There are different C60 domains with various misorientation angles relative to the lattice directions of Cd (0001). In the (2√3 × 2√3) R30° domain, orientational disorder of the individual C60 molecules with either pentagon, hexagon, or 6:6 bond facing up has been observed. However, orientation ordering appeared in the R26° domain such that all the C60 molecules adopt the same orientation with the 6:6 bond facing up. In particular, complex chiral motifs composed of seven C60 molecules with clockwise or anticlockwise handedness have been observed in the R4° and R8° domains, respectively. Scanning tunneling spectroscopy (STS) measurements reveal a reduced HOMO–LOMO gap of 2.1 eV for the C60 molecules adsorbed on Cd (0001) due to the substrate screening and charge transfer from Cd to C60 molecules.
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9
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Liu Z, Sun K, Li X, Li L, Zhang H, Chi L. Electronic Decoupling of Organic Layers by a Self-Assembled Supramolecular Network on Au(111). J Phys Chem Lett 2019; 10:4297-4302. [PMID: 31318568 DOI: 10.1021/acs.jpclett.9b01167] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A cyanuric acid and melamine (CA·M) supramolecular network, prepared via the drop-casting method under ambient conditions, can be utilized as a spacer layer to decouple electronic interactions between upper organics and the metal substrate. Typical semiconducting organics 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) and C60 are deposited on the CA·M network under ultrahigh vacuum conditions, forming an organics/CA·M/metal heterosystem. Both geometric and electronic structures of the upper organics are characterized by using scanning tunneling microscopy/spectroscopy (STM/STS). On the CA·M network, PTCDA molecules form a well-ordered herringbone structure in submonolayer patterns, whereas C60 molecules aggregate into multilayered islands. STS spectra reveal that the energy gap between the highest occupied and the lowest unoccupied molecular orbitals (HOMO - LUMO) is 3.6 eV for PTCDA and 3.8 eV for the first layer of C60 on CA·M. The remarkable bandgap broadening compared with the metal-organic contact indicates successful electronic decoupling of the upper molecules from the metal surface due to the CA·M network.
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Affiliation(s)
- Zhonghua Liu
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices , Soochow University , 199 Ren'ai Road , Suzhou , 215123 , Jiangsu , PR China
| | - Kewei Sun
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices , Soochow University , 199 Ren'ai Road , Suzhou , 215123 , Jiangsu , PR China
| | - Xuechao Li
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices , Soochow University , 199 Ren'ai Road , Suzhou , 215123 , Jiangsu , PR China
| | - Ling Li
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices , Soochow University , 199 Ren'ai Road , Suzhou , 215123 , Jiangsu , PR China
| | - Haiming Zhang
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices , Soochow University , 199 Ren'ai Road , Suzhou , 215123 , Jiangsu , PR China
| | - Lifeng Chi
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices , Soochow University , 199 Ren'ai Road , Suzhou , 215123 , Jiangsu , PR China
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10
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Hudaya C, Ahn M, Oh SH, Jeon BJ, Sung YE, Lee JK. Simultaneous etching and transfer — Free multilayer graphene sheets derived from C60 thin films. J IND ENG CHEM 2018. [DOI: 10.1016/j.jiec.2018.01.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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11
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Chen C, Mills A, Zheng H, Li Y, Tao C. Preparation and Characterization of C60/Graphene Hybrid Nanostructures. J Vis Exp 2018. [PMID: 29863668 DOI: 10.3791/57257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Physical thermal deposition in a high vacuum environment is a clean and controllable method for fabricating novel molecular nanostructures on graphene. We present methods for depositing and passively manipulating C60 molecules on rippled graphene that advance the pursuit of realizing applications involving 1D C60/graphene hybrid structures. The techniques applied in this exposition are geared towards high vacuum systems with preparation areas capable of supporting molecular deposition as well as thermal annealing of the samples. We focus on C60 deposition at low pressure using a homemade Knudsen cell connected to a scanning tunneling microscopy (STM) system. The number of molecules deposited is regulated by controlling the temperature of the Knudsen cell and the deposition time. One-dimensional (1D) C60 chain structures with widths of two to three molecules can be prepared via tuning of the experimental conditions. The surface mobility of the C60 molecules increases with annealing temperature allowing them to move within the periodic potential of the rippled graphene. Using this mechanism, it is possible to control the transition of 1D C60 chain structures to a hexagonal close packed quasi-1D stripe structure.
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Affiliation(s)
- Chuanhui Chen
- Department of Physics, Center for Soft Matter and Biological Physics, Virginia Tech
| | - Adam Mills
- Department of Physics, Center for Soft Matter and Biological Physics, Virginia Tech; Department of Physics, Princeton University
| | - Husong Zheng
- Department of Physics, Center for Soft Matter and Biological Physics, Virginia Tech
| | - Yanlong Li
- Department of Physics, Center for Soft Matter and Biological Physics, Virginia Tech
| | - Chenggang Tao
- Department of Physics, Center for Soft Matter and Biological Physics, Virginia Tech;
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12
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Tian T, Shih CJ. Molecular Epitaxy on Two-Dimensional Materials: The Interplay between Interactions. Ind Eng Chem Res 2017. [DOI: 10.1021/acs.iecr.7b02669] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tian Tian
- Institute for Chemical and
Bioengineering, ETH Zürich, Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland
| | - Chih-Jen Shih
- Institute for Chemical and
Bioengineering, ETH Zürich, Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland
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13
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Santos EJG, Scullion D, Chu XS, Li DO, Guisinger NP, Wang QH. Rotational superstructure in van der Waals heterostructure of self-assembled C 60 monolayer on the WSe 2 surface. NANOSCALE 2017; 9:13245-13256. [PMID: 28853477 DOI: 10.1039/c7nr03951d] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Hybrid van der Waals (vdW) heterostructures composed of two-dimensional (2D) layered materials and self-assembled organic molecules are promising systems for electronic and optoelectronic applications with enhanced properties and performance. Control of molecular assembly is therefore paramount to fundamentally understand the nucleation, ordering, alignment, and electronic interaction of organic molecules with 2D materials. Here, we report the formation and detailed study of highly ordered, crystalline monolayers of C60 molecules self-assembled on the surface of WSe2 in well-ordered arrays with large grain sizes (∼5 μm). Using high-resolution scanning tunneling microscopy (STM), we observe a periodic 2 × 2 superstructure in the C60 monolayer and identify four distinct molecular appearances. Using vdW-corrected ab initio density functional theory (DFT) simulations, we determine that the interplay between vdW and Coulomb interactions as well as adsorbate-adsorbate and adsorbate-substrate interactions results in specific rotational arrangements of the molecules forming the superstructure. The orbital ordering through the relative positions of bonds in adjacent molecules creates a charge redistribution that links the molecule units in a long-range network. This rotational superstructure extends throughout the self-assembled monolayer and opens a pathway towards engineering aligned hybrid organic/inorganic vdW heterostructures with 2D layered materials in a precise and controlled way.
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Affiliation(s)
- Elton J G Santos
- School of Mathematics and Physics, Queen's University Belfast, BT7 1NN, UK.
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14
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Kumar A, Banerjee K, Liljeroth P. Molecular assembly on two-dimensional materials. NANOTECHNOLOGY 2017; 28:082001. [PMID: 28045007 DOI: 10.1088/1361-6528/aa564f] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Molecular self-assembly is a well-known technique to create highly functional nanostructures on surfaces. Self-assembly on two-dimensional (2D) materials is a developing field driven by the interest in functionalization of 2D materials in order to tune their electronic properties. This has resulted in the discovery of several rich and interesting phenomena. Here, we review this progress with an emphasis on the electronic properties of the adsorbates and the substrate in well-defined systems, as unveiled by scanning tunneling microscopy. The review covers three aspects of the self-assembly. The first one focuses on non-covalent self-assembly dealing with site-selectivity due to inherent moiré pattern present on 2D materials grown on substrates. We also see that modification of intermolecular interactions and molecule-substrate interactions influences the assembly drastically and that 2D materials can also be used as a platform to carry out covalent and metal-coordinated assembly. The second part deals with the electronic properties of molecules adsorbed on 2D materials. By virtue of being inert and possessing low density of states near the Fermi level, 2D materials decouple molecules electronically from the underlying metal substrate and allow high-resolution spectroscopy and imaging of molecular orbitals. The moiré pattern on the 2D materials causes site-selective gating and charging of molecules in some cases. The last section covers the effects of self-assembled, acceptor and donor type, organic molecules on the electronic properties of graphene as revealed by spectroscopy and electrical transport measurements. Non-covalent functionalization of 2D materials has already been applied for their application as catalysts and sensors. With the current surge of activity on building van der Waals heterostructures from atomically thin crystals, molecular self-assembly has the potential to add an extra level of flexibility and functionality for applications ranging from flexible electronics and OLEDs to novel electronic devices and spintronics.
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Affiliation(s)
- Avijit Kumar
- Department of Applied Physics Aalto, University School of Science, PO Box 15100, FI-00076 Aalto, Finland
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15
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Gonzalez Arellano DL, Lee H, Secor EB, Burnett EK, Hersam MC, Watkins JJ, Briseno AL. Graphene Ink as a Conductive Templating Interlayer for Enhanced Charge Transport of C 60-Based Devices. ACS APPLIED MATERIALS & INTERFACES 2016; 8:29594-29599. [PMID: 27723296 DOI: 10.1021/acsami.6b05536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We demonstrate conductive templating interlayers of graphene ink, integrating the electronic and chemical properties of graphene in a solution-based process relevant for scalable manufacturing. Thin films of graphene ink are coated onto ITO, following thermal annealing, to form a percolating network used as interlayer. We employ a benchmark n-type semiconductor, C60, to study the interface of the active layer/interlayer. On bare ITO, C60 molecules form films of homogeneously distributed grains; with a graphene interlayer, a preferential orientation of C60 molecules is observed in the individual graphene plates. This leads to crystal growth favoring enhanced charge transport. We fabricate devices to characterize the electron injection and the effect of graphene on the device performance. We observe a significant increase in the current density with the interlayer. Current densities as high as ∼1 mA/cm2 and ∼70 mA/cm2 are realized for C60 deposited with the substrate at 25 °C and 150 °C, respectively.
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Affiliation(s)
- D Leonardo Gonzalez Arellano
- Department of Polymer Science and Engineering, University of Massachusetts , Amherst, Massachusetts 01003, United States
| | - Hyunbok Lee
- Department of Physics, Kangwon National University , 1 Gangwondaehak-gil, 24341, Republic of Korea
| | - Ethan B Secor
- Department of Materials Science and Engineering and Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Edmund K Burnett
- Department of Polymer Science and Engineering, University of Massachusetts , Amherst, Massachusetts 01003, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering and Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - James J Watkins
- Department of Polymer Science and Engineering, University of Massachusetts , Amherst, Massachusetts 01003, United States
| | - Alejandro L Briseno
- Department of Polymer Science and Engineering, University of Massachusetts , Amherst, Massachusetts 01003, United States
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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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Jung M, Sohn SD, Park J, Lee KU, Shin HJ. Fingerprints of Multiple Electron Scatterings in Single-Layer Graphene. Sci Rep 2016; 6:22570. [PMID: 26936521 PMCID: PMC4776258 DOI: 10.1038/srep22570] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 02/18/2016] [Indexed: 11/09/2022] Open
Abstract
The electrons in graphene exhibit unusual behaviours, which can be described by massless Dirac quasiparticles. Understanding electron scattering in graphene has been of significant importance for its future application in electronic devices because electron scattering determines electrical properties such as resistivity and electron transport. There are two types of electron scatterings in graphene: intervalley scattering and intravalley scattering. In single-layer graphene, to date, it has been difficult to observe intravalley scattering because of the suppression of backscattering resulting from the chiral nature of the electrons in graphene. Here, we report the multiple electron scattering behaviours in single-layer graphene on a metallic substrate. By applying one- and two-dimensional Fourier transforms to maps of the local density of states, we can distinguish individual scattering processes from complex interference patterns. These techniques enable us to provide direct evidence of intravalley scattering, revealing a linear dispersion relation with a Fermi velocity of ~7.4 × 10(5) m/s.
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Affiliation(s)
- Minbok Jung
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan 44919, Republic of Korea.,Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS) Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), UNIST-gil 50, Ulsan 44919, Republic of Korea
| | - So-Dam Sohn
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan 44919, Republic of Korea
| | - Jonghyun Park
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan 44919, Republic of Korea
| | - Keun-U Lee
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan 44919, Republic of Korea.,KIST-UNIST Ulsan Center for Convergent Materials, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan 44919, Republic of Korea
| | - Hyung-Joon Shin
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan 44919, Republic of Korea.,Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS) Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), UNIST-gil 50, Ulsan 44919, Republic of Korea.,KIST-UNIST Ulsan Center for Convergent Materials, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan 44919, Republic of Korea
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18
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Temperature Evolution of Quasi-one-dimensional C60 Nanostructures on Rippled Graphene. Sci Rep 2015; 5:14336. [PMID: 26391054 PMCID: PMC4585716 DOI: 10.1038/srep14336] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 08/25/2015] [Indexed: 11/08/2022] Open
Abstract
We report the preparation of novel quasi-one-dimensional (quasi-1D) C60 nanostructures on rippled graphene. Through careful control of the subtle balance between the linear periodic potential of rippled graphene and the C60 surface mobility, we demonstrate that C60 molecules can be arranged into a quasi-1D C60 chain structure with widths of two to three molecules. At a higher annealing temperature, the quasi-1D chain structure transitions to a more compact hexagonal close packed quasi-1D stripe structure. This first experimental realization of quasi-1D C60 structures on graphene may pave a way for fabricating new C60/graphene hybrid structures for future applications in electronics, spintronics and quantum information.
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19
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Kim K, Lee TH, Santos EJG, Jo PS, Salleo A, Nishi Y, Bao Z. Structural and Electrical Investigation of C60-Graphene Vertical Heterostructures. ACS NANO 2015; 9:5922-5928. [PMID: 26027690 DOI: 10.1021/acsnano.5b00581] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Graphene, with its unique electronic and structural qualities, has become an important playground for studying adsorption and assembly of various materials including organic molecules. Moreover, organic/graphene vertical structures assembled by van der Waals interaction have potential for multifunctional device applications. Here, we investigate structural and electrical properties of vertical heterostructures composed of C60 thin film on graphene. The assembled film structure of C60 on graphene is investigated using transmission electron microscopy, which reveals a uniform morphology of C60 film on graphene with a grain size as large as 500 nm. The strong epitaxial relations between C60 crystal and graphene lattice directions are found, and van der Waals ab initio calculations support the observed phenomena. Moreover, using C60-graphene heterostructures, we fabricate vertical graphene transistors incorporating n-type organic semiconducting materials with an on/off ratio above 3 × 10(3). Our work demonstrates that graphene can serve as an excellent substrate for assembly of molecules, and attained organic/graphene heterostructures have great potential for electronics applications.
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Affiliation(s)
- Kwanpyo Kim
- ‡Department of Physics, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Korea
| | | | - Elton J G Santos
- #School of Mathematics and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN, United Kingdom
- ∧School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Belfast BT9 5AL, United Kingdom
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20
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Shunaev VV, Savostyanov GV, Slepchenkov MM, Glukhova OE. Phenomenon of current occurrence during the motion of a C60 fullerene on substrate-supported graphene. RSC Adv 2015. [DOI: 10.1039/c5ra12202c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
It was found for the first time that the motion of a fullerene on graphene creates a small current.
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Affiliation(s)
- V. V. Shunaev
- Department of Physics
- Saratov State University
- Saratov
- Russia
| | | | | | - O. E. Glukhova
- Department of Physics
- Saratov State University
- Saratov
- Russia
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