1
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Yin H, Lin H, Zhang Y, Huang S. Iron(II) Phthalocyanine Adsorbed on Defective Graphenes: A Density Functional Study. ACS Omega 2022; 7:43915-43922. [PMID: 36506202 PMCID: PMC9730508 DOI: 10.1021/acsomega.2c05170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 11/08/2022] [Indexed: 06/17/2023]
Abstract
The adsorptions of iron(II) phthalocyanine (FePc) on graphene and defective graphene were investigated systematically using density functional theory. Three types of graphene defects covering stone-wales (SW), single vacancy (SV), and double vacancy (DV) were taken into account, in which DV defects included DV(5-8-5), DV(555-777), and DV(5555-6-7777). The calculations of formation energies of defects showed that the SW defect has the lowest formation energy, and it was easier for DV defects to form compared with the SV defect. It is more difficult to rotate or move FePc on the surface of defective graphenes than on the surface of graphene due to bigger energy differences at different sites. Although the charge analysis indicated the charge transfers from graphene or defective graphene to FePc for all studied systems, the electron distributions of FePc on various defective graphenes were different. Especially for FePc@SV, the d xy orbital of Fe in the conduction band moved toward the Fermi level about 1 eV, and the d xz of Fe in the valence band for FePc@SV also moved toward the Fermi level compared with FePc@graphene and other FePc@defective graphenes. Between the planes of FePc and defective graphene, the electron accumulation occurs majorly in the position of the FePc molecular plane for FePc@SW, FePc@DV(5-8-5), and FePc@DV(5555-6-7777) as well as FePc@graphene. However, electrons were accumulated on the upper and lower surfaces of the FePc molecular plane for FePc@SV and FePc@DV(555-777). Thus, the electron distribution of FePc can be modulated by introducing the interfaces of different defective graphenes.
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Affiliation(s)
- Huimin Yin
- College
of Chemistry, Fuzhou University, Fuzhou, Fujian350108, P. R. China
| | - Heyun Lin
- College
of Chemistry, Fuzhou University, Fuzhou, Fujian350108, P. R. China
| | - Yongfan Zhang
- College
of Chemistry, Fuzhou University, Fuzhou, Fujian350108, P. R. China
| | - Shuping Huang
- College
of Chemistry, Fuzhou University, Fuzhou, Fujian350108, P. R. China
- Fujian
Provincial Key Laboratory of Electrochemical Energy Storage Materials, Fuzhou, Fujian350108, P. R. China
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2
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Mirabito T, Huet B, Redwing JM, Snyder DW. Influence of the Underlying Substrate on the Physical Vapor Deposition of Zn-Phthalocyanine on Graphene. ACS Omega 2021; 6:20598-20610. [PMID: 34396005 PMCID: PMC8359151 DOI: 10.1021/acsomega.1c02758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 07/15/2021] [Indexed: 06/13/2023]
Abstract
Graphene shows great promise not only as a highly conductive flexible and transparent electrode for fabricating novel device architectures but also as an ideal synthesis platform for studying fundamental growth mechanisms of various materials. In particular, directly depositing metal phthalocyanines (MPc's) on graphene is viewed as a compelling approach to improve the performance of organic photovoltaics and light-emitting diodes. In this work, we systematically investigate the ZnPc physical vapor deposition (PVD) on graphene either as-grown on Cu or as-transferred on various substrates including Si(100), C-plane sapphire, SiO2/Si, and h-BN. To better understand the effect of the substrate on the ZnPc structure and morphology, we also compare the ZnPc growth on highly crystalline single- and multilayer graphene. The experiments show that, for identical deposition conditions, ZnPc exhibits various morphologies such as high-aspect-ratio nanowires or a continuous film when changing the substrate supporting graphene. ZnPc morphology is also found to transition from a thin film to a nanowire structure when increasing the number of graphene layers. Our observations suggest that substrate-induced changes in graphene affect the adsorption, surface diffusion, and arrangement of ZnPc molecules. This study provides clear guidelines to control MPc crystallinity, morphology, and molecular orientations which drastically influence the (opto)electronic properties.
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Affiliation(s)
- Timothy Mirabito
- Applied
Research Laboratory (ARL), The Pennsylvania
State University, University
Park, Pennsylvania 16802, United States
- Department
of Materials Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
- 2D Crystal
Consortium (2DCC), Materials Research Institute (MRI), The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Benjamin Huet
- Applied
Research Laboratory (ARL), The Pennsylvania
State University, University
Park, Pennsylvania 16802, United States
- Department
of Materials Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
- 2D Crystal
Consortium (2DCC), Materials Research Institute (MRI), The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Joan M. Redwing
- Department
of Materials Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
- 2D Crystal
Consortium (2DCC), Materials Research Institute (MRI), The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - David W. Snyder
- Applied
Research Laboratory (ARL), The Pennsylvania
State University, University
Park, Pennsylvania 16802, United States
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3
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Cortés-arriagada D, Miranda-rojas S, Cid-mora F, Toro-labbé A. First-principles study of hybrid nanostructures formed by deposited phthalocyanine/porphyrin metal complexes on phosphorene. J Mol Liq 2021; 333:115948. [DOI: 10.1016/j.molliq.2021.115948] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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4
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Deng D, Wu Q. Raman spectroscopy of copper phthalocyanine/graphene and 2,3,5,6‐tetrafluoro‐tetracyano‐quino‐dimethane/graphene interfaces. SURF INTERFACE ANAL 2021. [DOI: 10.1002/sia.6934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Ding‐Rong Deng
- College of Mechanical and Energy Engineering, Key Laboratory of Energy Cleaning Utilization, Development, Cleaning Combustion and Energy Utilization Research Center of Fujian Province Jimei University Xiamen China
| | - Qi‐Hui Wu
- College of Mechanical and Energy Engineering, Key Laboratory of Energy Cleaning Utilization, Development, Cleaning Combustion and Energy Utilization Research Center of Fujian Province Jimei University Xiamen China
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5
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Wang H, Yang X, Dou W, Wang P, Ye Q, Yang X, Li B, Mao H. Impact of Graphene Work Function on the Electronic Structures at the Interface between Graphene and Organic Molecules. Nanomaterials (Basel) 2019; 9:E1136. [PMID: 31394772 DOI: 10.3390/nano9081136] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 08/05/2019] [Accepted: 08/06/2019] [Indexed: 11/21/2022]
Abstract
The impact of graphene work function (WF) on the electronic structure at the graphene/organic interface has been investigated. WF manipulation of graphene is realized using self-assembled monolayers (SAMs) with different end groups. With this method, the upper surface of the functionalized graphene remains intact, and thus precludes changes of molecular orientation and packing structures of subsequently deposited active materials. The WF of NH2-SAM functionalized graphene is ~3.90 eV. On the other hand, the WF of graphene increases to ~5.38 eV on F-SAM. By tuning the WF of graphene, an upward band bending is found at the ZnPc/graphene interface on F-SAM. At the interface between C60 and NH2-SAM modified graphene, a downward band bending is observed.
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6
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Amsterdam SH, Stanev TK, Zhou Q, Lou AJT, Bergeron H, Darancet P, Hersam MC, Stern NP, Marks TJ. Electronic Coupling in Metallophthalocyanine-Transition Metal Dichalcogenide Mixed-Dimensional Heterojunctions. ACS Nano 2019; 13:4183-4190. [PMID: 30848891 DOI: 10.1021/acsnano.8b09166] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Mixed-dimensional heterojunctions, such as zero-dimensional (0D) organic molecules deposited on two-dimensional (2D) transition metal dichalcogenides (TMDCs), often exhibit interfacial effects that enhance the properties of the individual constituent layers. Here we report a systematic study of interfacial charge transfer in metallophthalocyanine (MPc) - MoS2 heterojunctions using optical absorption and Raman spectroscopy to elucidate M core (M = first row transition metal), MoS2 layer number, and excitation wavelength effects. Observed phenomena include the emergence of heterojunction-specific optical absorption transitions and strong Raman enhancement that depends on the M identity. In addition, the Raman enhancement is tunable by excitation laser wavelength and MoS2 layer number, ultimately reaching a maximum enhancement factor of 30x relative to SiO2 substrates. These experimental results, combined with density functional theory (DFT) calculations, indicate strong coupling between nonfrontier MPc orbitals and the MoS2 band structure as well as charge transfer across the heterojunction interface that varies as a function of the MPc electronic structure.
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Affiliation(s)
- Samuel H Amsterdam
- Department of Chemistry and the Materials Research Center , Northwestern University , Evanston , Illinois 60208 , United States
- Center for Light Energy Activated Redox Processes , Evanston , Illinois 60208 , United States
| | - Teodor K Stanev
- Department of Physics and Astronomy , Northwestern University , Evanston , Illinois 60208 , United States
| | - Qunfei Zhou
- Department of Materials Science and Engineering and the Materials Research Center , Northwestern University , Evanston , Illinois 60208 , United States
- Center for Nanoscale Materials , Argonne National Laboratory , Lemont , Illinois 60439 , United States
| | - Alexander J-T Lou
- Department of Chemistry and the Materials Research Center , Northwestern University , Evanston , Illinois 60208 , United States
| | - Hadallia Bergeron
- Department of Materials Science and Engineering and the Materials Research Center , Northwestern University , Evanston , Illinois 60208 , United States
| | - Pierre Darancet
- Center for Nanoscale Materials , Argonne National Laboratory , Lemont , Illinois 60439 , United States
- Northwestern Argonne Institute for Science and Engineering , Evanston , Illinois 60208 , United States
| | - Mark C Hersam
- Department of Chemistry and the Materials Research Center , Northwestern University , Evanston , Illinois 60208 , United States
- Center for Light Energy Activated Redox Processes , Evanston , Illinois 60208 , United States
- Department of Materials Science and Engineering and the Materials Research Center , Northwestern University , Evanston , Illinois 60208 , United States
| | - Nathaniel P Stern
- Department of Physics and Astronomy , Northwestern University , Evanston , Illinois 60208 , United States
- Northwestern Argonne Institute for Science and Engineering , Evanston , Illinois 60208 , United States
| | - Tobin J Marks
- Department of Chemistry and the Materials Research Center , Northwestern University , Evanston , Illinois 60208 , United States
- Center for Light Energy Activated Redox Processes , Evanston , Illinois 60208 , United States
- Department of Materials Science and Engineering and the Materials Research Center , Northwestern University , Evanston , Illinois 60208 , United States
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7
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Mehler A, Néel N, Bocquet ML, Kröger J. Exciting vibrons in both frontier orbitals of a single hydrocarbon molecule on graphene. J Phys Condens Matter 2019; 31:065001. [PMID: 30523960 DOI: 10.1088/1361-648x/aaf54c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Vibronic excitations in molecules are key to the fundamental understanding of the interaction between vibrational and electronic degrees of freedom. In order to probe the genuine vibronic properties of a molecule even after its adsorption on a surface appropriate buffer layers are of paramount importance. Here, vibrational progression in both molecular frontier orbitals is observed with submolecular resolution on a graphene-covered metal surface using scanning tunnelling spectroscopy. Accompanying calculations demonstrate that the vibrational modes that cause the orbital replica in the progression share the same symmetry as the electronic states they couple to. In addition, the vibrational progression is more pronounced for separated molecules than for molecules embedded in molecular assemblies. The entire vibronic spectra of these molecular species are moreover rigidly shifted with respect to each other. This work unravels intramolecular changes in the vibronic and electronic structure owing to the efficient reduction of the molecule-metal hybridization by graphene.
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Affiliation(s)
- A Mehler
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
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8
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Ahn H, Huang YC, Lin CW, Chiu YL, Lin EC, Lai YY, Lee YH. Efficient Defect Healing of Transition Metal Dichalcogenides by Metallophthalocyanine. ACS Appl Mater Interfaces 2018; 10:29145-29152. [PMID: 30044602 DOI: 10.1021/acsami.8b09378] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted great attention as alternatives to graphene with semiconducting band gaps. Mono- or few-layer TMDCs can be prepared by various methods, but regardless of the fabrication methods [such as mechanical exfoliation and chemical vapor deposition (CVD)], TMDCs contain many structural defects, which significantly affect their physical properties and limit their performance in applications. Metallophthalocyanines (MPcs) are organic semiconductors, and as dopants, they are capable of modulating the optical and electrical properties of other semiconducting materials. Here, we report that besides the ability to modulate the optoelectronic properties of 2D TMDCs, MPc molecules can be used to heal defects and improve the physicochemical properties of TMDCs. Doping of planar MPc molecules to TMDCs is achieved by a simple solution dip-coating method and results in a significant improvement in the optical properties and thermal responses of CVD-grown TMDCs, even comparable to those of mechanically exfoliated counterparts. Study of carrier dynamics shows that the adsorption of MPc on the TMDC surface leads to the complete suppression of the mid-gap defect-induced absorption in TMDCs. Furthermore, MPc molecules with a large lateral size are found to effectively reduce the point defects in mechanically exfoliated TMDCs introduced during the preparation process. Our results not only clarify the optoelectronic modulation mechanism of chemical doping but also offer a simple method to control the nanosized defects in 2D TMDCs.
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Affiliation(s)
- Hyeyoung Ahn
- Department of Photonics , National Chiao Tung University , Hsinchu 30010 , Taiwan
| | - Yu-Chiao Huang
- Department of Photonics , National Chiao Tung University , Hsinchu 30010 , Taiwan
| | - Chang-Wei Lin
- Department of Photonics , National Chiao Tung University , Hsinchu 30010 , Taiwan
| | - Yi-Lun Chiu
- Department of Photonics , National Chiao Tung University , Hsinchu 30010 , Taiwan
| | - Erh-Chen Lin
- Institute of NanoEngineering and MicroSystems , National Tsing-Hua University , Hsinchu 30010 , Taiwan
| | - Ying-Yu Lai
- Institute of NanoEngineering and MicroSystems , National Tsing-Hua University , Hsinchu 30010 , Taiwan
| | - Yi-Hsien Lee
- Institute of NanoEngineering and MicroSystems , National Tsing-Hua University , Hsinchu 30010 , Taiwan
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9
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Bouvron S, Maurand R, Graf A, Erler P, Gragnaniello L, Skripnik M, Wiedmann D, Engesser C, Nef C, Fu W, Schönenberger C, Pauly F, Fonin M. Charge transport in a single molecule transistor probed by scanning tunneling microscopy. Nanoscale 2018; 10:1487-1493. [PMID: 29303194 DOI: 10.1039/c7nr06860c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on the scanning tunneling microscopy/spectroscopy (STM/STS) study of cobalt phthalocyanine (CoPc) molecules deposited onto a back-gated graphene device. We observe a clear gate voltage (Vg) dependence of the energy position of the features originating from the molecular states. Based on the analysis of the energy shifts of the molecular features upon tuning Vg, we are able to determine the nature of the electronic states that lead to a gapped differential conductance. Our measurements show that capacitive couplings of comparable strengths exist between the CoPc molecule and the STM tip as well as between CoPc and graphene, thus facilitating electronic transport involving only unoccupied molecular states for both tunneling bias polarities. These findings provide novel information on the interaction between graphene and organic molecules and are of importance for further studies, which envisage the realization of single molecule transistors with non-metallic electrodes.
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Affiliation(s)
- Samuel Bouvron
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany.
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10
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Calborean A, Morari C, Maldivi P. Combined molecular and periodic DFT analysis of the adsorption of co macrocycles on graphene. J Comput Chem 2018; 39:130-138. [PMID: 29094373 DOI: 10.1002/jcc.25093] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 09/27/2017] [Accepted: 10/16/2017] [Indexed: 01/09/2023]
Abstract
The molecular doping of graphene with π-stacked conjugated molecules has been widely studied during the last 10 years, both experimentally or using first-principle calculations, mainly with strongly acceptor or donor molecules. Macrocyclic metal complexes have been far less studied and their behavior on graphene is less clear-cut. The present density functional theory study of cobalt porphyrin and phthalocyanine adsorbed on monolayer or bilayer graphene allows to compare the outcomes of two models, either a finite-sized flake of graphene or an infinite 2D material using periodic calculations. The electronic structures yielded by both models are compared, with a focus on the density of states around the Fermi level. Apart from the crucial choice of calculation conditions, this investigation also shows that unlike strongly donating or accepting organic dopants, these macrocycles do not induce a significant doping of the graphene sheet and that a finite size model of graphene flake may be confidently used for most modeling purposes. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Adrian Calborean
- National Institute for Research and Development of Isotopic and Molecular Technologies, Department of Molecular and Biomolecular Physics, Donat 67-103, Cluj-Napoca, 400293, Romania
| | - Cristian Morari
- National Institute for Research and Development of Isotopic and Molecular Technologies, Department of Molecular and Biomolecular Physics, Donat 67-103, Cluj-Napoca, 400293, Romania
| | - Pascale Maldivi
- University of Grenoble Alpes, CEA, CNRS, INAC, SYMMES, Grenoble, F-38000, France
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11
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Liu L, Xiao W, Mao J, Zhang H, Jiang Y, Zhou H, Yang K, Gao H. Densely packed overlayer of iron phthalocyanine molecules grown on single-layer graphene. CHINESE CHEM LETT 2018. [DOI: 10.1016/j.cclet.2017.06.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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12
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Quinn T, Choudhury P. Direct oxidation of methane to methanol on single-site copper-oxo species of copper porphyrin functionalized graphene: A DFT study. Molecular Catalysis 2017. [DOI: 10.1016/j.mcat.2017.01.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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13
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Wäckerlin A, Fatayer S, Nijs T, Nowakowska S, Mousavi SF, Popova O, Ahsan A, Jung TA, Wäckerlin C. Molecular Chessboard Assemblies Sorted by Site-Specific Interactions of Out-of-Plane d-Orbitals with a Semimetal Template. Nano Lett 2017; 17:1956-1962. [PMID: 28157314 DOI: 10.1021/acs.nanolett.6b05344] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We show that highly ordered two-dimensional (2D) chessboard arrays consisting of a periodic arrangement of two different molecules can be obtained by self-assembly of unsubstituted metal-phthalocyanines (metal-Pcs) on a suitable substrate serving as the template. Specifically, CuPc + MnPc and CuPc + CoPc mixtures sort into highly ordered Cu/Mn and Cu/Co chessboard arrays on the square p(10 × 10) reconstruction of bismuth on Cu(100). Such created bimolecular chessboard assemblies emerge from the site-specific interactions between the central transition-metal ions and the periodically reconstructed substrate. This work provides a conceptually new approach to induce 2D chessboard patterns in that no functionalization of the molecules is needed.
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Affiliation(s)
- Aneliia Wäckerlin
- Department of Physics, University of Basel , 4056 Basel, Switzerland
| | - Shadi Fatayer
- Department of Physics, University of Basel , 4056 Basel, Switzerland
- Departamento de Física Aplicada, Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas , Campinas 13083-859, Brazil
| | - Thomas Nijs
- Department of Physics, University of Basel , 4056 Basel, Switzerland
| | - Sylwia Nowakowska
- Department of Physics, University of Basel , 4056 Basel, Switzerland
| | - S Fatemeh Mousavi
- Department of Physics, University of Basel , 4056 Basel, Switzerland
| | - Olha Popova
- Department of Physics, University of Basel , 4056 Basel, Switzerland
| | - Aisha Ahsan
- Department of Physics, University of Basel , 4056 Basel, Switzerland
| | - Thomas A Jung
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut , 5232 Villigen PSI, Switzerland
| | - Christian Wäckerlin
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut , 5232 Villigen PSI, Switzerland
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14
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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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Ciesielski A, Samorì P. Supramolecular Approaches to Graphene: From Self-Assembly to Molecule-Assisted Liquid-Phase Exfoliation. Adv Mater 2016; 28:6030-51. [PMID: 26928750 DOI: 10.1002/adma.201505371] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Revised: 11/29/2015] [Indexed: 05/19/2023]
Abstract
Graphene, a one-atom thick two-dimensional (2D) material, is at the core of an ever-growing research effort due to its combination of unique mechanical, thermal, optical and electrical properties. Two strategies are being pursued for the graphene production: the bottom-up and the top-down. The former relies on the use of covalent chemistry approaches on properly designed molecular building blocks undergoing chemical reaction to form 2D covalent networks. The latter occurs via exfoliation of bulk graphite into individual graphene sheets. Amongst the various types of exfoliations exploited so far, ultrasound-induced liquid-phase exfoliation (UILPE) is an attractive strategy, being extremely versatile, up-scalable and applicable to a variety of environments. In this review, we highlight the recent developments that have led to successful non-covalent functionalization of graphene and how the latter can be exploited to promote the process of molecule-assisted UILPE of graphite. The functionalization of graphene with non-covalently interacting molecules, both in dispersions as well as in dry films, represents a promising and modular approach to tune various physical and chemical properties of graphene, eventually conferring to such a 2D system a multifunctional nature.
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Affiliation(s)
- Artur Ciesielski
- Nanochemistry Laboratory, ISIS & icFRC, Université de Strasbourg & CNRS, 8 allée Gaspard Monge, 67000, Strasbourg, France
| | - Paolo Samorì
- Nanochemistry Laboratory, ISIS & icFRC, Université de Strasbourg & CNRS, 8 allée Gaspard Monge, 67000, Strasbourg, France
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16
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Topyła M, Néel N, Kröger J. Superstructures and Electronic Properties of Manganese-Phthalocyanine Molecules on Au(110) from Submonolayer Coverage to Ultrathin Molecular Films. Langmuir 2016; 32:6843-6850. [PMID: 27322189 DOI: 10.1021/acs.langmuir.6b01529] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The adsorption of manganese-phthalocyanine molecules on Au(110) was investigated using a low-temperature scanning tunneling microscope. A rich variety of commensurate superstructures was observed upon increasing the molecule coverage from submonolayers to ultrathin films. All structures were associated with reconstructions of the Au(110) substrate. Molecules adsorbed in the second molecular layer exhibited negative differential conductance occurring symmetrically around zero bias voltage. A double-barrier tunneling model rationalized this observation in terms of a peaked molecular resonance at the Fermi energy together with a voltage drop across the molecular film.
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Affiliation(s)
- M Topyła
- Institut für Physik, Technische Universität Ilmenau , D-98693 Ilmenau, Germany
| | - N Néel
- Institut für Physik, Technische Universität Ilmenau , D-98693 Ilmenau, Germany
| | - J Kröger
- Institut für Physik, Technische Universität Ilmenau , D-98693 Ilmenau, Germany
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17
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Néel N, Lattelais M, Bocquet ML, Kröger J. Depopulation of Single-Phthalocyanine Molecular Orbitals upon Pyrrolic-Hydrogen Abstraction on Graphene. ACS Nano 2016; 10:2010-6. [PMID: 26812093 DOI: 10.1021/acsnano.5b06153] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Single-molecule chemistry with a scanning tunneling microscope has preponderantly been performed on metal surfaces. The molecule-metal hybridization, however, is often detrimental to genuine molecular properties and obscures their changes upon chemical reactions. We used graphene on Ir(111) to reduce the coupling between Ir(111) and adsorbed phthalocyanine molecules. By local electron injection from the tip of a scanning tunneling microscope the two pyrrolic H atoms were removed from single phthalocyanines. The detachment of the H atom pair induced a strong modification of the molecular electronic structure, albeit with no change in the adsorption geometry. Spectra and maps of the differential conductance combined with density functional calculations unveiled the entire depopulation of the highest occupied molecular orbital upon H abstraction. Occupied π states of intact molecules are proposed to be emptied via intramolecular electron transfer to dangling σ states of H-free N atoms.
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Affiliation(s)
- Nicolas Néel
- Institut für Physik, Technische Universität Ilmenau , D-98693 Ilmenau, Germany
| | - Marie Lattelais
- Department of Chemistry, UMR ENS-CNRS-UPMC 8640, Ecole Normale Supérieure , F-75005 Paris, France
| | - Marie-Laure Bocquet
- Department of Chemistry, UMR ENS-CNRS-UPMC 8640, Ecole Normale Supérieure , F-75005 Paris, France
| | - Jörg Kröger
- Institut für Physik, Technische Universität Ilmenau , D-98693 Ilmenau, Germany
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Dou WD, Huang SP, Lee CS. Graphene-enhanced intermolecular interaction at interface between copper- and cobalt-phthalocyanines. J Chem Phys 2016; 143:134706. [PMID: 26450327 DOI: 10.1063/1.4932192] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Interfacial electronic structures of copper-phthalocyanine (CuPc), cobalt-phthalocyanine (CoPc), and graphene were investigated experimentally by using photoelectron spectroscopy. While the CuPc/graphene interface shows flat band structure and negligible interfacial dipole indicating quite weak molecule-substrate interaction, the CuPc/CoPc/graphene interface shows a large interfacial dipole and obvious energy level bending. Controlled experiments ruled out possible influences from the change in film structure of CuPc and pure π-π interaction between CoPc and CuPc. Analysis based on X-ray photoelectron spectroscopy and density functional theory reveals that the decrease in the work function for the CuPc/CoPc/graphene system is induced by the intermolecular interaction between CuPc and CoPc which is enhanced owning to the peculiar electronic properties at the CoPc-graphene interface.
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Affiliation(s)
- Wei-Dong Dou
- Department of Physics, Shaoxing University, Shaoxing 312000, China
| | - Shu-Ping Huang
- Department of Chemistry, University of South Dakota, Vermillion, South Dakota 57069, USA
| | - Chun-Sing Lee
- Center of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Material Science, City University of Hong Kong, Hong Kong, China
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Wagner SR, Huang B, Park C, Feng J, Yoon M, Zhang P. Growth of Metal Phthalocyanine on Deactivated Semiconducting Surfaces Steered by Selective Orbital Coupling. Phys Rev Lett 2015; 115:096101. [PMID: 26371664 DOI: 10.1103/physrevlett.115.096101] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Indexed: 05/20/2023]
Abstract
Using scanning tunneling microscopy and density functional theory, we show that the molecular ordering and orientation of metal phthalocyanine molecules on the deactivated Si surface display a strong dependency on the central transition-metal ion, driven by the degree of orbital hybridization at the heterointerface via selective p-d orbital coupling. This Letter identifies a selective mechanism for modifying the molecule-substrate interaction which impacts the growth behavior of transition-metal-incorporated organic molecules on a technologically relevant substrate for silicon-based devices.
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Affiliation(s)
- Sean R Wagner
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-2320, USA
| | - Bing Huang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Changwon Park
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Jiagui Feng
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-2320, USA
| | - Mina Yoon
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Pengpeng Zhang
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-2320, USA
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Affiliation(s)
| | - Donghang Yan
- State
Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, People’s Republic of China
| | - Tim S. Jones
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
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21
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Dinca LE, De Marchi F, MacLeod JM, Lipton-Duffin J, Gatti R, Ma D, Perepichka DF, Rosei F. Pentacene on Ni(111): room-temperature molecular packing and temperature-activated conversion to graphene. Nanoscale 2015; 7:3263-3269. [PMID: 25619890 DOI: 10.1039/c4nr07057g] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We investigate, using scanning tunnelling microscopy, the adsorption of pentacene on Ni(111) at room temperature and the behaviour of these monolayer films with annealing up to 700 °C. We observe the conversion of pentacene into graphene, which begins from as low as 220 °C with the coalescence of pentacene molecules into large planar aggregates. Then, by annealing at 350 °C for 20 minutes, these aggregates expand into irregular domains of graphene tens of nanometers in size. On surfaces where graphene and nickel carbide coexist, pentacene shows preferential adsorption on the nickel carbide phase. The same pentacene to graphene transformation was also achieved on Cu(111), but at a higher activation temperature, producing large graphene domains that exhibit a range of moiré superlattice periodicities.
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Affiliation(s)
- L E Dinca
- Centre Énergie, Matériaux et Télécommunications, Institut National de la Recherche Scientifique, Université du Québec, 1650 boulevard Lionel-Boulet, Varennes, QC J3X 1S2, Canada.
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22
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Mali KS, Greenwood J, Adisoejoso J, Phillipson R, De Feyter S. Nanostructuring graphene for controlled and reproducible functionalization. Nanoscale 2015; 7:1566-1585. [PMID: 25553734 DOI: 10.1039/c4nr06470d] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The 'graphene rush' that started almost a decade ago is far from over. The dazzling properties of graphene have long warranted a number of applications in various domains of science and technology. Harnessing the exceptional properties of graphene for practical applications however has proved to be a massive task. Apart from the challenges associated with the large-scale production of the material, the intrinsic zero band gap, the inherently low reactivity and solubility of pristine graphene preclude its use in several high- as well as low-end applications. One of the potential solutions to these problems is the surface functionalization of graphene using organic building blocks. The 'surface-only' nature of graphene allows the manipulation of its properties not only by covalent chemical modification but also via non-covalent interactions with organic molecules. Significant amount of research efforts have been directed towards the development of functionalization protocols for modifying the structural, electronic, and chemical properties of graphene. This feature article provides a glimpse of recent progress in the molecular functionalization of surface supported graphene using non-covalent as well as covalent chemistry.
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Affiliation(s)
- Kunal S Mali
- KU Leuven-University of Leuven, Department of Chemistry, Division of Molecular Imaging and Photonics Celestijnenlaan 200F, B-3001 Leuven, Belgium.
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23
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Rouillé G, Kirchhuebel T, Rink M, Gruenewald M, Kröger J, Forker R, Fritz T. Identification of vibrational excitations and optical transitions of the organic electron donor tetraphenyldibenzoperiflanthene (DBP). Phys Chem Chem Phys 2015; 17:30404-16. [DOI: 10.1039/c5cp03761a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The spectra of DBP grains (IR) and rare-gas-matrix-isolated molecules (UV/vis) are used to analyze HREELS and DRS measurements of DBP molecules adsorbed on Au(111) and mica(0001).
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Affiliation(s)
- Gaël Rouillé
- Laboratory Astrophysics Group of the Max Planck Institute for Astronomy at the Friedrich Schiller University Jena
- Institute of Solid State Physics
- 07743 Jena
- Germany
| | - Tino Kirchhuebel
- Institute of Solid State Physics
- Friedrich Schiller University
- 07743 Jena
- Germany
| | - Marcel Rink
- Institut für Physik
- Technische Universität Ilmenau
- 98693 Ilmenau
- Germany
| | - Marco Gruenewald
- Institute of Solid State Physics
- Friedrich Schiller University
- 07743 Jena
- Germany
| | - Jörg Kröger
- Institut für Physik
- Technische Universität Ilmenau
- 98693 Ilmenau
- Germany
| | - Roman Forker
- Institute of Solid State Physics
- Friedrich Schiller University
- 07743 Jena
- Germany
| | - Torsten Fritz
- Institute of Solid State Physics
- Friedrich Schiller University
- 07743 Jena
- Germany
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24
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Endlich M, Gozdzik S, Néel N, da Rosa AL, Frauenheim T, Wehling TO, Kröger J. Phthalocyanine adsorption to graphene on Ir(111): Evidence for decoupling from vibrational spectroscopy. J Chem Phys 2014; 141:184308. [PMID: 25399148 DOI: 10.1063/1.4901283] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- M. Endlich
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - S. Gozdzik
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - N. Néel
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - A. L. da Rosa
- Bremen Center for Computational Materials Science, University Bremen, D-28359 Bremen, Germany
- Department of Physics, Federal University of Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil
| | - T. Frauenheim
- Bremen Center for Computational Materials Science, University Bremen, D-28359 Bremen, Germany
| | - T. O. Wehling
- Bremen Center for Computational Materials Science, University Bremen, D-28359 Bremen, Germany
- Institute for Theoretical Physics, University Bremen, D-28359 Bremen, Germany
| | - J. Kröger
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
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26
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Abstract
The formation of ordered arrays of molecules via self-assembly is a rapid, scalable route towards the realization of nanoscale architectures with tailored properties. In recent years, graphene has emerged as an appealing substrate for molecular self-assembly in two dimensions. Here, the first five years of progress in supramolecular organization on graphene are reviewed. The self-assembly process can vary depending on the type of graphene employed: epitaxial graphene, grown in situ on a metal surface, and non-epitaxial graphene, transferred onto an arbitrary substrate, can have different effects on the final structure. On epitaxial graphene, the process is sensitive to the interaction between the graphene and the substrate on which it is grown. In the case of graphene that strongly interacts with its substrate, such as graphene/Ru(0001), the inhomogeneous adsorption landscape of the graphene moiré superlattice provides a unique opportunity for guiding molecular organization, since molecules experience spatially constrained diffusion and adsorption. On weaker-interacting epitaxial graphene films, and on non-epitaxial graphene transferred onto a host substrate, self-assembly leads to films similar to those obtained on graphite surfaces. The efficacy of a graphene layer for facilitating planar adsorption of aromatic molecules has been repeatedly demonstrated, indicating that it can be used to direct molecular adsorption, and therefore carrier transport, in a certain orientation, and suggesting that the use of transferred graphene may allow for predictible molecular self-assembly on a wide range of surfaces.
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Affiliation(s)
- J M MacLeod
- Centre Énergie Matériaux Télécommunications, Institut national de la recherche scientifique, 1650 Boul. Lionel-Boulet, Varennes, QC, J3X 1S2, Canada
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27
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Massimi L, Lisi S, Pacilè D, Mariani C, Betti MG. Interaction of iron phthalocyanine with the graphene/Ni(111) system. Beilstein J Nanotechnol 2014; 5:308-12. [PMID: 24778953 PMCID: PMC3999856 DOI: 10.3762/bjnano.5.34] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2013] [Accepted: 02/17/2014] [Indexed: 05/28/2023]
Abstract
Graphene grown on crystalline metal surfaces is a good candidate to act as a buffer layer between the metal and organic molecules that are deposited on top, because it offers the possibility to control the interaction between the substrate and the molecules. High-resolution angular-resolved ultraviolet photo electron spectroscopy (ARPES) is used to determine the interaction states of iron phthalocyanine molecules that are adsorbed onto graphene on Ni(111). The iron phthalocyanine deposition induces a quenching of the Ni d surface minority band and the appearance of an interface state on graphene/Ni(111). The results have been compared to the deposition of iron phthalocyanine on graphene/Ir(111), for which a higher decoupling of the organic molecule from the underlying metal is exerted by the graphene buffer layer.
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Affiliation(s)
- Lorenzo Massimi
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale A. Moro 2, I-00185 Roma, Italia
| | - Simone Lisi
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale A. Moro 2, I-00185 Roma, Italia
| | - Daniela Pacilè
- Dipartimento di Fisica, Università della Calabria, I-87036 Arcavacata di Rende (CS), Italia
| | - Carlo Mariani
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale A. Moro 2, I-00185 Roma, Italia
| | - Maria Grazia Betti
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale A. Moro 2, I-00185 Roma, Italia
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Brinkhaus L, Katsukis G, Malig J, Costa RD, Garcia-Iglesias M, Vázquez P, Torres T, Guldi DM. Tuning the stability of graphene layers by phthalocyanine-based oPPV oligomers towards photo- and redoxactive materials. Small 2013; 9:2348-2357. [PMID: 23418045 DOI: 10.1002/smll.201202427] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 12/25/2012] [Indexed: 06/01/2023]
Abstract
In contrast to pristine zinc phthalocyanine (1), zinc phthalocyanine based oPPV-oligomers (2-4) of different chain lengths interact tightly and reversibly with graphite, affording stable and finely dispersed suspensions of mono- to few-layer graphene-nanographene (NG)-that are photoactive. The p-type character of the oPPV backbones and the increasing length of the oPPV backbones facilitate the overall π-π interactions with the graphene layers. In NG/2, NG/3, and NG/4 hybrids, strong electronic coupling between the individual components gives rise to charge transfer from the photoexcited zinc phthalocyanines to NG to form hundreds of picoseconds lived charge transfer states. The resulting features, namely photo- and redoxactivity, serve as incentives to construct and to test novel solar cells. Solar cells made out of NG/4 feature stable and repeatable photocurrent generation during several 'on-off' cycles of illumination with monochromatic IPCE values of around 1%.
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Affiliation(s)
- Linda Brinkhaus
- Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
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Dou WD, Yang Q, Lee CS. The effects of oxygen on controlling the number of carbon layers in the chemical vapor deposition of graphene on a nickel substrate. Nanotechnology 2013; 24:185603. [PMID: 23575390 DOI: 10.1088/0957-4484/24/18/185603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
While oxygen is typically considered undesirable during the chemical vapor deposition (CVD) of graphene on metal substrates, we demonstrate that suitable amounts of oxygen in the CVD system can in fact improve the uniformity and thickness control of the graphene film. The role of oxygen on the CVD of graphene on a nickel substrate using a propylene precursor was investigated with various surface analytical techniques. It was found that the number of carbon layers in the deposited graphene sample decreases as the concentration of oxygen increases. In particular, single-layer graphene can be easily obtained with an oxygen/propylene ratio of 1/9. In the presence of oxygen, a thin layer of nickel oxide will form on the substrate. The oxide layer decreases the concentration of carbon atoms dissolved in the nickel substrate and results in graphene samples with a decreasing number of carbon layers.
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Affiliation(s)
- Wei-Dong Dou
- Physics Department, Shaoxing University, Shaoxing 312000, People's Republic of China
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Uihlein J, Peisert H, Glaser M, Polek M, Adler H, Petraki F, Ovsyannikov R, Bauer M, Chassé T. Communication: Influence of graphene interlayers on the interaction between cobalt phthalocyanine and Ni(111). J Chem Phys 2013; 138:081101. [DOI: 10.1063/1.4793523] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Xiao K, Deng W, Keum JK, Yoon M, Vlassiouk IV, Clark KW, Li AP, Kravchenko II, Gu G, Payzant EA, Sumpter BG, Smith SC, Browning JF, Geohegan DB. Surface-induced orientation control of CuPc molecules for the epitaxial growth of highly ordered organic crystals on graphene. J Am Chem Soc 2013; 135:3680-7. [PMID: 23368998 DOI: 10.1021/ja3125096] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The epitaxial growth and preferred molecular orientation of copper phthalocyanine (CuPc) molecules on graphene has been systematically investigated and compared with growth on Si substrates, demonstrating the role of surface-mediated interactions in determining molecular orientation. X-ray scattering and diffraction, scanning tunneling microscopy, scanning electron microscopy, and first-principles theoretical calculations were used to show that the nucleation, orientation, and packing of CuPc molecules on films of graphene are fundamentally different compared to those grown on Si substrates. Interfacial dipole interactions induced by charge transfer between CuPc molecules and graphene are shown to epitaxially align the CuPc molecules in a face-on orientation in a series of ordered superstructures. At high temperatures, CuPc molecules lie flat with respect to the graphene substrate to form strip-like CuPc crystals with micrometer sizes containing monocrystalline grains. Such large epitaxial crystals may potentially enable improvement in the device performance of organic thin films, wherein charge transport, exciton diffusion, and dissociation are currently limited by grain size effects and molecular orientation.
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Affiliation(s)
- Kai Xiao
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
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Ling X, Wu J, Xu W, Zhang J. Probing the effect of molecular orientation on the intensity of chemical enhancement using graphene-enhanced Raman spectroscopy. Small 2012; 8:1365-72. [PMID: 22359411 DOI: 10.1002/smll.201102223] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Revised: 12/09/2011] [Indexed: 05/17/2023]
Abstract
A rational approach to investigate the effect of molecular orientation on the intensity of chemical enhancement using graphene-enhanced Raman spectroscopy (GERS) is developed. A planar molecule, copper phthalocyanine (CuPc), is used as probe molecule. Annealing allows the CuPc molecule in a Langmuir-Blodgett film to change orientation from upstanding to lying down. The UV-visible absorption spectra prove the change of the molecular orientation, as well as the variation of the interaction between the CuPc molecule and graphene. The Raman spectra of the molecule in the two different orientations are compared and analyzed. The results show that chemical enhancement is highly sensitive to the molecular orientation. The different molecular orientations induce different magnitudes of the interaction between the molecule and graphene. The stronger the interaction, the more the Raman signal is enhanced. Furthermore, the sensitivity of GERS to molecular orientation is promising to determine the orientation of the molecule on graphene. Based on this molecular orientation sensitive Raman enhancement, quantitative calculation of the magnitude of the chemical enhancement is implemented for a series of Pc derivatives. It shows that the magnitude of the chemical enhancement can be used to evaluate the degree of interaction between the molecules and graphene. Moreover, an understanding of the chemical enhancement in GERS is promoted and the effect of molecular orientation on the intensity of chemical enhancement is explained.
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Affiliation(s)
- Xi Ling
- Center for Nanochemistry, Beijing National Laboratory for Molecular Sciences, Key Laboratory for the Physics and Chemistry of Nanodevices, College of Chemistry and Molecular Engineering, Peking University, Beijing, PR China
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Umeyama T, Mihara J, Tezuka N, Matano Y, Stranius K, Chukharev V, Tkachenko NV, Lemmetyinen H, Noda K, Matsushige K, Shishido T, Liu Z, Hirose-Takai K, Suenaga K, Imahori H. Preparation and Photophysical and Photoelectrochemical Properties of a Covalently Fixed Porphyrin-Chemically Converted Graphene Composite. Chemistry 2012; 18:4250-7. [DOI: 10.1002/chem.201103843] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Indexed: 11/11/2022]
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Affiliation(s)
- Jian Zhou
- Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871, China
| | - Qiang Sun
- Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871, China
- Center for Applied Physics and Technology, Peking University, Beijing 100871, China
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