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Zhao G, Song M, Chung HS, Kim SM, Lee SG, Bae JS, Bae TS, Kim D, Lee GH, Han SZ, Lee HS, Choi EA, Yun J. Optical Transmittance Enhancement of Flexible Copper Film Electrodes with a Wetting Layer for Organic Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2017; 9:38695-38705. [PMID: 29039201 DOI: 10.1021/acsami.7b10234] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The development of highly efficient flexible transparent electrodes (FTEs) supported on polymer substrates is of great importance to the realization of portable and bendable photovoltaic devices. Highly conductive, low-cost Cu has attracted attention as a promising alternative for replacing expensive indium tin oxide (ITO) and Ag. However, highly efficient, Cu-based FTEs are currently unavailable because of the absence of an efficient means of attaining an atomically thin, completely continuous Cu film that simultaneously exhibits enhanced optical transmittance and electrical conductivity. Here, strong two-dimensional (2D) epitaxy of Cu on ZnO is reported by applying an atomically thin (around 1 nm) oxygen-doped Cu wetting layer. Analyses of transmission electron microscopy images and X-ray diffraction patterns, combined with first-principles density functional theory calculations, reveal that the reduction in the surface and interface free energies of the wetting layers with a trace amount (1-2 atom %) of oxygen are largely responsible for the two-dimensional epitaxial growth of the Cu on ZnO. The ultrathin 2D Cu layer, embedded between ZnO films, exhibits a highly desirable optical transmittance of over 85% in a wavelength range of 400-800 nm and a sheet resistance of 11 Ω sq-1. The validity of this innovative approach is verified with a Cu-based FTE that contributes to the light-to-electron conversion efficiency of a flexible organic solar cell that incorporates the transparent electrode (7.7%), which far surpasses that of a solar cell with conventional ITO (6.4%).
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Affiliation(s)
| | | | - Hee-Suk Chung
- Jeonju Center, Korea Basic Science Institute , Jeonju, Jeonbuk 54907, Republic of Korea
| | - Soo Min Kim
- Department of Materials Science and Engineering, Korea University , Seoul 02841, Republic of Korea
| | - Sang-Geul Lee
- Daegu Center, Korea Basic Science Institute , Daegu 41566, Republic of Korea
| | - Jong-Seong Bae
- Busan Center, Korea Basic Science Institute , Busan 46742, Republic of Korea
| | - Tae-Sung Bae
- Jeonju Center, Korea Basic Science Institute , Jeonju, Jeonbuk 54907, Republic of Korea
| | - Donghwan Kim
- Department of Materials Science and Engineering, Korea University , Seoul 02841, Republic of Korea
| | | | | | - Hae-Seok Lee
- KU-KIST Green School, Graduate School of Energy and Environment, Korea University , Seoul 02841, Republic of Korea
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Hu J, Song Y, Huang J, Li Y, Chen M, Wan H. New Insights into the Role of Al 2 O 3 in the Promotion of CuZnAl Catalysts: A Model Study. Chemistry 2017; 23:10632-10637. [PMID: 28544004 DOI: 10.1002/chem.201701697] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Indexed: 11/05/2022]
Abstract
The Cu/Al2 O3 /ZnO(0001)-Zn ternary model catalysts and their binary analogues were prepared and characterized. It was found that Al2 O3 grew on the ZnO(0001)-Zn surface by a layer-by-layer model, whereas Cu grew on the ZnO(0001)-Zn surface as two-dimensional clusters up to 0.2 monolayers (ML), and thereafter formed three-dimensional clusters. Because of the layer-by-layer growth of Al2 O3 on the ZnO(0001)-Zn, Cu/Al2 O3 can be considered without the effect of ZnO. Ternary model catalyst Cu/Al2 O3 /ZnO(0001)-Zn, which has all three parts on the surface, was prepared by deposition of Cu on the surface of Al2 O3 /ZnO(0001)-Zn. Low-energy ion scattering spectra showed that Cu preferred to locate at the Al2 O3 /ZnO interfaces. Compared with Cu/ZnO, the addition of Al2 O3 obviously suppressed the reduction of copper oxides and led to a higher concentration of Cu+ . The Cu clusters were found to be covered by thin ZnOx overlayers after reduction of Cu/Al2 O3 /ZnO(0001)-Zn by using H2 . Therefore, the high activity of industrial Cu/ZnO/Al2 O3 catalysts may origin from Cu+ -rich clusters at the Al2 O3 /ZnO interface that are covered by thin ZnOx overlayers.
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Affiliation(s)
- Jun Hu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, Fujian, P. R. China
| | - Yanying Song
- State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, Fujian, P. R. China
| | - Junjie Huang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, Fujian, P. R. China
| | - Yangyang Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, Fujian, P. R. China
| | - Mingshu Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, Fujian, P. R. China
| | - Huilin Wan
- State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, Fujian, P. R. China
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Borghetti P, Mouchaal Y, Dai Z, Cabailh G, Chenot S, Lazzari R, Jupille J. Orientation-dependent chemistry and band-bending of Ti on polar ZnO surfaces. Phys Chem Chem Phys 2017; 19:10350-10357. [PMID: 28379222 DOI: 10.1039/c6cp08595d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Orientation-dependent reactivity and band-bending are evidenced upon Ti deposition (1-10 Å) on polar ZnO(0001)-Zn and ZnO(0001[combining macron])-O surfaces. At the onset of the Ti deposition, a downward band-bending was observed on ZnO(0001[combining macron])-O while no change occurred on ZnO(0001)-Zn. Combining this with the photoemission analysis of the Ti 2p core level and Zn L3(L2)M45M45 Auger transition, it is established that the Ti/ZnO reaction is of the form Ti + 2ZnO → TiO2 + 2Zn on ZnO(0001)-Zn and Ti + yZnO → TiZnxOy + (y - x)Zn on ZnO(0001[combining macron])-O. Consistently, upon annealing thicker Ti adlayers, the metallic zinc is removed to leave ZnO(0001)-Zn surfaces covered with a TiO2-like phase and ZnO(0001[combining macron])-O surfaces covered with a defined (Ti, Zn, O) compound. Finally, a difference in the activation temperature between the O-terminated (500 K) and Zn-terminated (700 K) surfaces is observed, which is tentatively explained by different electric fields in the space charge layer at ZnO surfaces.
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Affiliation(s)
- Patrizia Borghetti
- Sorbonne Universités, CNRS-UMR 7588, UPMC Univ Paris 06, Institut des NanoSciences de Paris, F-75005, Paris, France.
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Beinik I, Hellström M, Jensen TN, Broqvist P, Lauritsen JV. Enhanced wetting of Cu on ZnO by migration of subsurface oxygen vacancies. Nat Commun 2015; 6:8845. [PMID: 26567989 PMCID: PMC4660204 DOI: 10.1038/ncomms9845] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Accepted: 10/06/2015] [Indexed: 12/02/2022] Open
Abstract
Metal adhesion on metal oxides is strongly controlled by the oxide surface structure and composition, but lack of control over the surface conditions often limits the possibilities to exploit this in opto- and micro-electronics applications and heterogeneous catalysis where nanostructural control is of utmost importance. The Cu/ZnO system is among the most investigated of such systems in model studies, but the presence of subsurface ZnO defects and their important role for adhesion on ZnO have been unappreciated so far. Here we reveal that the surface-directed migration of subsurface defects affects the Cu adhesion on polar ZnO(0001) in the technologically interesting temperature range up to 550 K. This leads to enhanced adhesion and ultimately complete wetting of ZnO(0001) by a Cu overlayer. On the basis of our experimental and computational results we demonstrate a mechanism which implies that defect concentrations in the bulk are an important, and possibly controllable, parameter for the metal-on-oxide growth. Comprehensive elucidation of metal-support interactions is important for controlling and improving their performances in a range of pertinent technologies. Here, the authors reveal how subsurface defects influence the adhesion and wetting of a metal on the surface of a metal oxide.
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Affiliation(s)
- Igor Beinik
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus DK-8000, Denmark
| | - Matti Hellström
- Department of Chemistry-Ångström, Uppsala University, Box 538, Uppsala SE-75121, Sweden
| | - Thomas N Jensen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus DK-8000, Denmark
| | - Peter Broqvist
- Department of Chemistry-Ångström, Uppsala University, Box 538, Uppsala SE-75121, Sweden
| | - Jeppe V Lauritsen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus DK-8000, Denmark
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Hellström M, Spångberg D, Hermansson K. Treatment of delocalized electron transfer in periodic and embedded cluster DFT calculations: The case of Cu on ZnO (10 1¯0). J Comput Chem 2015; 36:2394-405. [DOI: 10.1002/jcc.24219] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 08/29/2015] [Accepted: 09/01/2015] [Indexed: 12/21/2022]
Affiliation(s)
- Matti Hellström
- Department of Chemistry - Ångström; Uppsala University; Box 538 Uppsala SE-75121 Sweden
| | - Daniel Spångberg
- Department of Chemistry - Ångström; Uppsala University; Box 538 Uppsala SE-75121 Sweden
| | - Kersti Hermansson
- Department of Chemistry - Ångström; Uppsala University; Box 538 Uppsala SE-75121 Sweden
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Posada-Pérez S, Viñes F, Rodríguez JA, Illas F. Structure and electronic properties of Cu nanoclusters supported on Mo2C(001) and MoC(001) surfaces. J Chem Phys 2015; 143:114704. [DOI: 10.1063/1.4930538] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Affiliation(s)
- Sergio Posada-Pérez
- Departament de Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/ Martí i Franquès 1, 08028 Barcelona, Spain
| | - Francesc Viñes
- Departament de Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/ Martí i Franquès 1, 08028 Barcelona, Spain
| | - José A. Rodríguez
- Chemistry Department, Brookhaven National Laboratory, Bldg. 555, Upton, New York 11973, USA
| | - Francesc Illas
- Departament de Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/ Martí i Franquès 1, 08028 Barcelona, Spain
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Silva H, Mateos-Pedrero C, Magén C, Pacheco Tanaka DA, Mendes A. Simple hydrothermal synthesis method for tailoring the physicochemical properties of ZnO: morphology, surface area and polarity. RSC Adv 2014. [DOI: 10.1039/c4ra05002a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Addou R, Senftle TP, O'Connor N, Janik MJ, van Duin ACT, Batzill M. Influence of hydroxyls on Pd atom mobility and clustering on rutile TiO(2)(011)-2 × 1. ACS NANO 2014; 8:6321-33. [PMID: 24806092 DOI: 10.1021/nn501817w] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Understanding agglomeration of late transition metal atoms, such as Pd, on metal oxide supports, such as TiO2, is critical for designing heterogeneous catalysts as well as for controlling metal/oxide interfaces in general. One approach for reducing particle sintering is to modify the metal oxide surface with hydroxyls that decrease adatom mobility. We study by scanning tunneling microscopy experiments, density functional theory (DFT) calculations, and Monte Carlo (MC) computer simulations the atomistic processes of Pd sintering on a hydroxyl-modified TiO2(011)-2 × 1 surface. The formation of small 1-3 atom clusters that are stable at room temperature is achieved on the hydroxylated surface, while much larger clusters are formed under the same conditions on a hydroxyl-free surface. DFT shows that this is a consequence of stronger binding of Pd atoms adjacent to hydroxyls and increased surface diffusion barriers for Pd atoms on the hydroxylated surface. DFT, kinetic MC, and ReaxFF-based NVT-MC simulations show that Pd clusters larger than single Pd monomers can adsorb the hydrogen from the oxide surface and form Pd hydrides. This depletes the surface hydroxyl coverage, thus allowing Pd to more freely diffuse and agglomerate at room temperature. Experimentally, this causes a bimodal cluster size distribution with 1-3 atom clusters prevalent at low Pd coverage, while significantly larger clusters become dominant at higher Pd concentrations. This study demonstrates that hydroxylated oxide surfaces can significantly reduce Pd cluster sizes, thus enabling the preparation of surfaces populated with metal clusters composed of single to few atoms.
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Affiliation(s)
- Rafik Addou
- Department of Physics, University of South Florida , Tampa, Florida 33620, United States
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Behler J. Representing potential energy surfaces by high-dimensional neural network potentials. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:183001. [PMID: 24758952 DOI: 10.1088/0953-8984/26/18/183001] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The development of interatomic potentials employing artificial neural networks has seen tremendous progress in recent years. While until recently the applicability of neural network potentials (NNPs) has been restricted to low-dimensional systems, this limitation has now been overcome and high-dimensional NNPs can be used in large-scale molecular dynamics simulations of thousands of atoms. NNPs are constructed by adjusting a set of parameters using data from electronic structure calculations, and in many cases energies and forces can be obtained with very high accuracy. Therefore, NNP-based simulation results are often very close to those gained by a direct application of first-principles methods. In this review, the basic methodology of high-dimensional NNPs will be presented with a special focus on the scope and the remaining limitations of this approach. The development of NNPs requires substantial computational effort as typically thousands of reference calculations are required. Still, if the problem to be studied involves very large systems or long simulation times this overhead is regained quickly. Further, the method is still limited to systems containing about three or four chemical elements due to the rapidly increasing complexity of the configuration space, although many atoms of each species can be present. Due to the ability of NNPs to describe even extremely complex atomic configurations with excellent accuracy irrespective of the nature of the atomic interactions, they represent a general and therefore widely applicable technique, e.g. for addressing problems in materials science, for investigating properties of interfaces, and for studying solvation processes.
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Affiliation(s)
- J Behler
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, D-44780 Bochum, Germany
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Walton A, Lauritsen J, Topsøe H, Besenbacher F. MoS2 nanoparticle morphologies in hydrodesulfurization catalysis studied by scanning tunneling microscopy. J Catal 2013. [DOI: 10.1016/j.jcat.2013.08.017] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Natesakhawat S, Ohodnicki PR, Howard BH, Lekse JW, Baltrus JP, Matranga C. Adsorption and Deactivation Characteristics of Cu/ZnO-Based Catalysts for Methanol Synthesis from Carbon Dioxide. Top Catal 2013. [DOI: 10.1007/s11244-013-0111-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Kroll M, Löber T, Schott V, Wöll C, Köhler U. Thermal behavior of MOCVD-grown Cu-clusters on ZnO(101̄0). Phys Chem Chem Phys 2012; 14:1654-9. [DOI: 10.1039/c2cp22901c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Lauritsen JV, Reichling M. Atomic resolution non-contact atomic force microscopy of clean metal oxide surfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:263001. [PMID: 21386455 DOI: 10.1088/0953-8984/22/26/263001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In the last two decades the atomic force microscope (AFM) has become the premier tool for topographical analysis of surface structures at the nanometre scale. In its ultimately sensitive implementation, namely dynamic scanning force microscopy (SFM) operated in the so-called non-contact mode (NC-AFM), this technique yields genuine atomic resolution and offers a unique tool for real space atomic-scale studies of surfaces, nanoparticles as well as thin films, single atoms and molecules on surfaces irrespective of the substrate being electrically conducting or non-conducting. Recent advances in NC-AFM have paved the way for groundbreaking atomic level insight into insulator surfaces, specifically in the most important field of metal oxides. NC-AFM imaging now strongly contributes to our understanding of the surface structure, chemical composition, defects, polarity and reactivity of metal oxide surfaces and related physical and chemical surface processes. Here we review the latest advancements in the field of NC-AFM applied to the fundamental atomic resolution studies of clean single crystal metal oxide surfaces with special focus on the representative materials Al(2)O(3)(0001), TiO(2)(110), ZnO(1000) and CeO(2)(111).
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Affiliation(s)
- J V Lauritsen
- Interdisciplinary Nanoscience Center, Aarhus University, Denmark.
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Abstract
The relation of surface science studies of single crystal metal oxides to gas sensing applications is reviewed. Most metal oxide gas sensors are used to detect oxidizing or reducing gases and therefore this article focuses on surface reduction processes and the interaction of oxygen with these surfaces. The systems that are discussed are: (i) the oxygen vacancy formation on the surface of the ion conductor CeO(2)(111); (ii) interaction of oxygen with TiO(2) (both adsorption processes and the incorporation of oxygen into the TiO(2)(110) lattice are discussed); (iii) the varying surface composition of SnO(2)(101) and its consequence for the adsorption of water; and (iv) Cu modified ZnO(0001)-Zn surfaces and its interaction with oxygen. These examples are chosen to give a comprehensive overview of surface science studies of different kinds of gas sensing materials and to illustrate the potential that surface science studies have to give fundamental insight into gas sensing phenomena.
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Affiliation(s)
- Matthias Batzill
- Department of Physics, University of South Florida, Tampa, FL, USA
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