101
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Li X, Xie D, Park H, Zhu M, Zeng TH, Wang K, Wei J, Wu D, Kong J, Zhu H. Ion doping of graphene for high-efficiency heterojunction solar cells. NANOSCALE 2013; 5:1945-1948. [PMID: 23358527 DOI: 10.1039/c2nr33795a] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We demonstrated the p-type chemical doping by chlorine and nitrate anions to enhance the Schottky junction in the solar cell. Nitrate ions were found to be more effective for reducing the sheet resistance and enlarging the work function of graphene for effective charge separation and transport, and the efficiency was increased to 9.2% by a factor of 1.68 under AM 1.5 illumination.
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Affiliation(s)
- Xinming Li
- School of Materials Science and Engineering, Tsinghua University, Beijing 100084, PR China
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102
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Lee SK, Rana K, Ahn JH. Graphene Films for Flexible Organic and Energy Storage Devices. J Phys Chem Lett 2013; 4:831-841. [PMID: 26281940 DOI: 10.1021/jz400005k] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Graphene and its derivatives have been the subject of extensive research in fundamental science and have viable applications in current and future technology. The exceptionally high electronic and thermal conductivity, optical transparency, and high specific surface area, combined with excellent mechanical flexibility and environmental stability leave graphene poised to be a material of the future. This perspective introduces the importance of graphene electrodes, discusses the synthesis of graphene and transfer onto desired substrates and the role of graphene in electrodes for a broad range of flexible devices such as photovoltaic, electronic, and electrochemical energy storage.
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Affiliation(s)
- Seoung-Ki Lee
- †School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, Korea
- ‡School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea
| | - Kuldeep Rana
- ‡School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea
| | - Jong-Hyun Ahn
- ‡School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea
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103
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Kim HH, Yang JW, Jo SB, Kang B, Lee SK, Bong H, Lee G, Kim KS, Cho K. Substrate-induced solvent intercalation for stable graphene doping. ACS NANO 2013; 7:1155-1162. [PMID: 23368414 DOI: 10.1021/nn306012p] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Here, we report a substrate-induced intercalation phenomenon of an organic solvent at the interface between monolayer graphene and a target substrate. A simple dipping of the transferred chemical vapor deposition (CVD)-grown graphene on the SiO₂ substrate into chloroform (CHCl₃, CF), a common organic solvent, induces a spontaneous formation of CF clusters beneath the basal plane of the graphene as well as inside the wrinkles. The microscopic and spectroscopic observations showed the doping behavior of monolayer graphene, which indicates the adsorption of CF to monolayer graphene. Interestingly, the intercalated organic solvent showed remarkable stability for over 40 days under ambient conditions. To reveal the underlying mechanism of the stable solvent intercalation, desorption energy of CF molecules at the graphene/substrate interface was measured using Arrhenius plots of the conductance change upon time and temperature. Two stages of solvent intercalations with high desorption energies (70 and 370 meV) were observed along with the consecutive shrinkage of the solvent clusters at the basal plane and the wrinkles, respectively. Moreover, the theoretical calculation based on density functional theory (DFT) also shows the strong intercalation energy of CF between monolayer graphene and the SiO₂ substrate, which results from the stabilization of the graphene-SiO₂ interactions. Furthermore, the thermal response of the conductance could be utilized to maintain a certain degree of p-doping of monolayer graphene, which provides the facile, sustainable, and controllable large-area doping method of graphene for future generation of printed flexible electronics.
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Affiliation(s)
- Hyun Ho Kim
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea
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104
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Abstract
Graphene is a true wonder material that promises much in a variety of applications that include electronic devices, supercapacitors, batteries, composites, flexible transparent displays and sensors. This review highlights the different methods available for the synthesis of graphene and discusses the viability and practicalities of using the materials produced via these methods for different graphene-based applications.
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Affiliation(s)
- Rebecca S Edwards
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, UK
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105
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Si P, Dong XC, Chen P, Kim DH. A hierarchically structured composite of Mn3O4/3D graphene foam for flexible nonenzymatic biosensors. J Mater Chem B 2013; 1:110-115. [DOI: 10.1039/c2tb00073c] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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106
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Perebeinos V, Tersoff J, Avouris P. Phonon-mediated interlayer conductance in twisted graphene bilayers. PHYSICAL REVIEW LETTERS 2012; 109:236604. [PMID: 23368236 DOI: 10.1103/physrevlett.109.236604] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Indexed: 06/01/2023]
Abstract
Conduction between graphene layers is suppressed by momentum conservation whenever the layer stacking has a rotation. Here we show that phonon scattering plays a crucial role in facilitating interlayer conduction. The resulting dependence on orientation is radically different than previously expected, and far more favorable for device applications. At low temperatures, we predict diode-like current-voltage characteristics due to a phonon bottleneck. Simple scaling relationships give a good description of the conductance as a function of temperature, doping, rotation angle, and bias voltage, reflecting the dominant role of the interlayer beating phonon mode.
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Affiliation(s)
- V Perebeinos
- IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
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107
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Kang J, Shin D, Bae S, Hong BH. Graphene transfer: key for applications. NANOSCALE 2012; 4:5527-5537. [PMID: 22864991 DOI: 10.1039/c2nr31317k] [Citation(s) in RCA: 179] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The first micrometer-sized graphene flakes extracted from graphite demonstrated outstanding electrical, mechanical and chemical properties, but they were too small for practical applications. However, the recent advances in graphene synthesis and transfer techniques have enabled various macroscopic applications such as transparent electrodes for touch screens and light-emitting diodes (LEDs) and thin-film transistors for flexible electronics in particular. With such exciting potential, a great deal of effort has been put towards producing larger size graphene in the hopes of industrializing graphene production. Little less than a decade after the first discovery, graphene now can be synthesized up to 30 inches in its diagonal size using chemical vapour deposition methods. In making this possible, it was not only the advances in the synthesis techniques but also the transfer methods that deliver graphene onto target substrates without significant mechanical damage. In this article, the recent advancements in transferring graphene to arbitrary substrates will be extensively reviewed. The methods are categorized into mechanical exfoliation, polymer-assisted transfer, continuous transfer by roll-to-roll process, and transfer-free techniques including direct synthesis on insulating substrates.
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Affiliation(s)
- Junmo Kang
- SKKU Advanced Institute of Nanotechnology and Center for Human Interface Nano Technology, Sungkyunkwan University, Suwon, 440-746, Korea.
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108
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Zhang C, Liu T. A review on hybridization modification of graphene and its polymer nanocomposites. ACTA ACUST UNITED AC 2012. [DOI: 10.1007/s11434-012-5321-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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109
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Kang J, Hwang S, Kim JH, Kim MH, Ryu J, Seo SJ, Hong BH, Kim MK, Choi JB. Efficient transfer of large-area graphene films onto rigid substrates by hot pressing. ACS NANO 2012; 6:5360-5365. [PMID: 22631604 DOI: 10.1021/nn301207d] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Graphene films grown on metal substrates by chemical vapor deposition (CVD) method have to be safely transferred onto desired substrates for further applications. Recently, a roll-to-roll (R2R) method has been developed for large-area transfer, which is particularly efficient for flexible target substrates. However, in the case of rigid substrates such as glass or wafers, the roll-based method is found to induce considerable mechanical damages on graphene films during the transfer process, resulting in the degradation of electrical property. Here we introduce an improved dry transfer technique based on a hot-pressing method that can minimize damage on graphene by neutralizing mechanical stress. Thus, we enhanced the transfer efficiency of the large-area graphene films on a substrate with arbitrary thickness and rigidity, evidenced by scanning electron microscope (SEM) and atomic force microscope (AFM) images, Raman spectra, and various electrical characterizations. We also performed a theoretical multiscale simulation from continuum to atomic level to compare the mechanical stresses caused by the R2R and the hot-pressing methods, which also supports our conclusion. Consequently, we believe that the proposed hot-pressing method will be immediately useful for display and solar cell applications that currently require rigid and large substrates.
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Affiliation(s)
- Junmo Kang
- SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon, 440-746, Korea
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110
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Hsu CL, Lin CT, Huang JH, Chu CW, Wei KH, Li LJ. Layer-by-layer graphene/TCNQ stacked films as conducting anodes for organic solar cells. ACS NANO 2012; 6:5031-9. [PMID: 22632158 DOI: 10.1021/nn301721q] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Large-area graphene grown by chemical vapor deposition (CVD) is a promising candidate for transparent conducting electrode applications in flexible optoelectronic devices such as light-emitting diodes or organic solar cells. However, the power conversion efficiency (PCE) of the polymer photovoltaic devices using a pristine CVD graphene anode is still not appealing due to its much lower conductivity than that of conventional indium tin oxide. We report a layer-by-layer molecular doping process on graphene for forming sandwiched graphene/tetracyanoquinodimethane (TCNQ)/graphene stacked films for polymer solar cell anodes, where the TCNQ molecules (as p-dopants) were securely embedded between two graphene layers. Poly(3-hexylthiophene)/phenyl-C61-butyric acid methyl ester (P3HT/PCBM) bulk heterojunction polymer solar cells based on these multilayered graphene/TCNQ anodes are fabricated and characterized. The P3HT/PCBM device with an anode structure composed of two TCNQ layers sandwiched by three CVD graphene layers shows optimum PCE (∼2.58%), which makes the proposed anode film quite attractive for next-generation flexible devices demanding high conductivity and transparency.
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Affiliation(s)
- Chang-Lung Hsu
- Department of Material Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan
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111
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Khrapach I, Withers F, Bointon TH, Polyushkin DK, Barnes WL, Russo S, Craciun MF. Novel highly conductive and transparent graphene-based conductors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:2844-9. [PMID: 22535615 PMCID: PMC3715101 DOI: 10.1002/adma.201200489] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 03/05/2012] [Indexed: 05/18/2023]
Abstract
Transparent conductors based on few-layer graphene (FLG) intercalated with ferric chloride (FeCl(3)) have an outstandingly low sheet resistance and high optical transparency. FeCl(3)-FLGs outperform the current limit of transparent conductors such as indium tin oxide, carbon-nanotube films, and doped graphene materials. This makes FeCl(3)-FLG materials the best transparent conductor for optoelectronic devices.
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Affiliation(s)
- Ivan Khrapach
- Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of ExeterExeter, EX4 4QL, UK E-mail:
| | - Freddie Withers
- Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of ExeterExeter, EX4 4QL, UK E-mail:
| | - Thomas H Bointon
- Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of ExeterExeter, EX4 4QL, UK E-mail:
| | - Dmitry K Polyushkin
- Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of ExeterExeter, EX4 4QL, UK E-mail:
| | - William L Barnes
- Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of ExeterExeter, EX4 4QL, UK E-mail:
| | - Saverio Russo
- Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of ExeterExeter, EX4 4QL, UK E-mail:
| | - Monica F Craciun
- Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of ExeterExeter, EX4 4QL, UK E-mail:
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112
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Ni GX, Zheng Y, Bae S, Tan CY, Kahya O, Wu J, Hong BH, Yao K, Özyilmaz B. Graphene-ferroelectric hybrid structure for flexible transparent electrodes. ACS NANO 2012; 6:3935-3942. [PMID: 22524641 DOI: 10.1021/nn3010137] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Graphene has exceptional optical, mechanical, and electrical properties, making it an emerging material for novel optoelectronics, photonics, and flexible transparent electrode applications. However, the relatively high sheet resistance of graphene is a major constraint for many of these applications. Here we propose a new approach to achieve low sheet resistance in large-scale CVD monolayer graphene using nonvolatile ferroelectric polymer gating. In this hybrid structure, large-scale graphene is heavily doped up to 3 × 10(13) cm(-2) by nonvolatile ferroelectric dipoles, yielding a low sheet resistance of 120 Ω/□ at ambient conditions. The graphene-ferroelectric transparent conductors (GFeTCs) exhibit more than 95% transmittance from the visible to the near-infrared range owing to the highly transparent nature of the ferroelectric polymer. Together with its excellent mechanical flexibility, chemical inertness, and the simple fabrication process of ferroelectric polymers, the proposed GFeTCs represent a new route toward large-scale graphene-based transparent electrodes and optoelectronics.
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Affiliation(s)
- Guang-Xin Ni
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
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113
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Dong XC, Xu H, Wang XW, Huang YX, Chan-Park MB, Zhang H, Wang LH, Huang W, Chen P. 3D graphene-cobalt oxide electrode for high-performance supercapacitor and enzymeless glucose detection. ACS NANO 2012; 6:3206-13. [PMID: 22435881 DOI: 10.1021/nn300097q] [Citation(s) in RCA: 715] [Impact Index Per Article: 59.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Using a simple hydrothermal procedure, cobalt oxide (Co(3)O(4)) nanowires were in situ synthesized on three-dimensional (3D) graphene foam grown by chemical vapor deposition. The structure and morphology of the resulting 3D graphene/Co(3)O(4) composites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. The 3D graphene/Co(3)O(4) composite was used as the monolithic free-standing electrode for supercapacitor application and for enzymeless electrochemical detection of glucose. We demonstrate that it is capable of delivering high specific capacitance of ∼1100 F g(-1) at a current density of 10 A g(-1) with excellent cycling stability, and it can detect glucose with a ultrahigh sensitivity of 3.39 mA mM(-1) cm(-2) and a remarkable lower detection limit of <25 nM (S/N = 8.5).
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Affiliation(s)
- Xiao-Chen Dong
- Key Laboratory for Organic Electronics & Information Displays (KLOEID), Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications (NUPT), 9 Wenyuan Road, Nanjing, 210046, China.
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114
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Feng T, Xie D, Lin Y, Zhao H, Chen Y, Tian H, Ren T, Li X, Li Z, Wang K, Wu D, Zhu H. Efficiency enhancement of graphene/silicon-pillar-array solar cells by HNO3 and PEDOT-PSS. NANOSCALE 2012; 4:2130-2133. [PMID: 22337348 DOI: 10.1039/c2nr12001a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A single-layer graphene film was grown on copper foil by chemical vapor deposition and transferred onto a silicon-pillar-array (SPA) substrate to make a Schottky junction solar cell. The SPA substrate was specifically designed to suppress reflectance and enhance light absorption. The energy conversion efficiency of the prepared graphene/SPA solar cells achieved a maximum of 2.90% with a junction area of 0.09 cm(2). HNO(3) was employed to dope the graphene in the solar cells, and the time dependence of HNO(3) treatment on the cell performance was studied. Poly(3,4-ethylenedioxythiophene) polystyrenesulfonic acid (PEDOT-PSS) was also introduced in graphene/SPA solar cells by spin coating on top of the graphene film, and its modification on the cell performance was characterized. The results show that both HNO(3) and the PEDOT-PSS film could enhance the energy conversion efficiency of graphene/SPA solar cells.
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Affiliation(s)
- Tingting Feng
- Tsinghua National Laboratory for Information Science and Technology (TNList), Institute of Microelectronics, Tsinghua University, Beijing 100084, PR China
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115
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Luo B, Liu S, Zhi L. Chemical approaches toward graphene-based nanomaterials and their applications in energy-related areas. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:630-46. [PMID: 22121112 DOI: 10.1002/smll.201101396] [Citation(s) in RCA: 171] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Indexed: 05/20/2023]
Abstract
A 'gold rush' has been triggered all over the world for exploiting the possible applications of graphene-based nanomaterials. For this purpose, two important problems have to be solved; one is the preparation of graphene-based nanomaterials with well-defined structures, and the other is the controllable fabrication of these materials into functional devices. This review gives a brief overview of the recent research concerning chemical and thermal approaches toward the production of well-defined graphene-based nanomaterials and their applications in energy-related areas, including solar cells, lithium ion secondary batteries, supercapacitors, and catalysis.
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Affiliation(s)
- Bin Luo
- National Center for Nanoscience and Technology, Zhongguancun, Beiyitiao No.11, Beijing, 100190, PR China
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116
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Nguyen DD, Tai NH, Chen SY, Chueh YL. Controlled growth of carbon nanotube-graphene hybrid materials for flexible and transparent conductors and electron field emitters. NANOSCALE 2012; 4:632-638. [PMID: 22147118 DOI: 10.1039/c1nr11328c] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report a versatile synthetic process based on rapid heating and cooling chemical vapor deposition for the growth of carbon nanotube (CNT)-graphene hybrid materials where the thickness of graphene and density of CNTs are properly controlled. Graphene films are demonstrated as an efficient barrier layer for preventing poisoning of iron nanoparticles, which catalyze the growth of CNTs on copper substrates. Based on this method, the opto-electronic and field emission properties of graphene integrated with CNTs can be remarkably tailored. A graphene film exhibits a sheet resistance of 2.15 kΩ sq(-1) with a transmittance of 85.6% (at 550 nm), while a CNT-graphene hybrid film shows an improved sheet resistance of 420 Ω sq(-1) with an optical transmittance of 72.9%. Moreover, CNT-graphene films are demonstrated as effective electron field emitters with low turn-on and threshold electric fields of 2.9 and 3.3 V μm(-1), respectively. The development of CNT-graphene films with a wide range of tunable properties presented in this study shows promising applications in flexible opto-electronic, energy, and sensor devices.
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Affiliation(s)
- Duc Dung Nguyen
- Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu, Taiwan 300, ROC
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117
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Lee S, Lee K, Liu CH, Zhong Z. Homogeneous bilayer graphene film based flexible transparent conductor. NANOSCALE 2012; 4:639-644. [PMID: 22146772 DOI: 10.1039/c1nr11574j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Graphene is considered as a promising candidate to replace conventional transparent conductors due to its low opacity, high carrier mobility and flexible structure. Multi-layer graphene or stacked single layer graphenes have been investigated in the past but both have their drawbacks. The uniformity of multi-layer graphene is still questionable, and single layer graphene stacks require many transfer processes to achieve sufficiently low sheet resistance. In this work, bilayer graphene film grown with low pressure chemical vapor deposition was used as a transparent conductor for the first time. The technique was demonstrated to be highly efficient in fabricating a conductive and uniform transparent conductor compared to multi-layer or single layer graphene. Four transfers of bilayer graphene yielded a transparent conducting film with a sheet resistance of 180 Ω(□) at a transmittance of 83%. In addition, bilayer graphene films transferred onto the plastic substrate showed remarkable robustness against bending, with sheet resistance change less than 15% at 2.14% strain, a 20-fold improvement over commercial indium oxide films.
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Affiliation(s)
- Seunghyun Lee
- Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Avenue, Ann Arbor, MI 48109-2122, USA
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118
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Das S, Sudhagar P, Ito E, Lee DY, Nagarajan S, Lee SY, Kang YS, Choi W. Effect of HNO3 functionalization on large scale graphene for enhanced tri-iodide reduction in dye-sensitized solar cells. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm32481d] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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119
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He M, Jung J, Qiu F, Lin Z. Graphene-based transparent flexible electrodes for polymer solar cells. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm33784c] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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120
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Kalita G, Wakita K, Umeno M. Low temperature growth of graphene film by microwave assisted surface wave plasma CVD for transparent electrode application. RSC Adv 2012. [DOI: 10.1039/c2ra00648k] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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121
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Zheng Q, Zhang B, Lin X, Shen X, Yousefi N, Huang ZD, Li Z, Kim JK. Highly transparent and conducting ultralarge graphene oxide/single-walled carbon nanotube hybrid films produced by Langmuir–Blodgett assembly. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm34870e] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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122
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Yan H, Xia F, Zhu W, Freitag M, Dimitrakopoulos C, Bol AA, Tulevski G, Avouris P. Infrared spectroscopy of wafer-scale graphene. ACS NANO 2011; 5:9854-9860. [PMID: 22077967 DOI: 10.1021/nn203506n] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report spectroscopy results from the mid- to far-infrared on wafer-scale graphene, grown either epitaxially on silicon carbide or by chemical vapor deposition. The free carrier absorption (Drude peak) is simultaneously obtained with the universal optical conductivity (due to interband transitions) and the wavelength at which Pauli blocking occurs due to band filling. From these, the graphene layer number, doping level, sheet resistivity, carrier mobility, and scattering rate can be inferred. The mid-IR absorption of epitaxial two-layer graphene shows a less pronounced peak at 0.37 ± 0.02 eV compared to that in exfoliated bilayer graphene. In heavily chemically doped single-layer graphene, a record high transmission reduction due to free carriers approaching 40% at 250 μm (40 cm(-1)) is measured in this atomically thin material, supporting the great potential of graphene in far-infrared and terahertz optoelectronics.
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Affiliation(s)
- Hugen Yan
- IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, United States
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123
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Huang YL, Baji A, Tien HW, Yang YK, Yang SY, Ma CCM, Liu HY, Mai YW, Wang NH. Self-assembly of graphene onto electrospun polyamide 66 nanofibers as transparent conductive thin films. NANOTECHNOLOGY 2011; 22:475603. [PMID: 22056343 DOI: 10.1088/0957-4484/22/47/475603] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A simple method was developed to assemble graphite oxide (GO) densely onto electrospun (ES) polyamide 66 (PA66) nanofibrous membranes, used as a guide for the deposition of graphene nanosheet (GNS) conductive networks for preparing transparent conductive thin film (TCF). The main advantage of this technique by comparison with previous methods is that graphene does not form a uniform coating, but a percolated conductive network, when guided by PA66 nanofiber templates. A low surface coverage of the transparent substrate by GNS resulted in high transmittance. Polyvinylpyrrolidone-stabilized GO (PVP-GO) was prepared as a modifier for improving the adsorption to the nanofibers. The resulting PVP-GO material could adsorb well on PA66 nanofibers due to stronger hydrogen bonds. Hence, a lower sufficient concentration of PVP-GO (0.050 wt%) solution was required than that for GO solution (0.100 wt%) to fabricate a complete conductive path through a possible enriched adsorption process. For TCF applications, a reduction step is essential because as-deposited GO is non-conductive. In this work, we reduced GO to GNS by a combination of chemical reduction and thermal annealing. The TCF optical transmittance also could be improved after thermal annealing at 350 °C above the PA66 melting point. Light scattering by PA66 nanofibers was found as the main cause of reduced transmittance. A fused film, obtained after electrospinning PA66 solution for 120 s, and immersing in 0.050 wt% PVP-GO solution, exhibits a surface resistance of 8.6 × 10³ Ω/square, while maintaining 88% light transmittance.
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Affiliation(s)
- Yuan-Li Huang
- Department of Chemical Engineering, National Tsing-Hua University, Hsin-Chu 30043, Taiwan
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124
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Kuroda MA, Tersoff J, Newns DM, Martyna GJ. Conductance through multilayer graphene films. NANO LETTERS 2011; 11:3629-3633. [PMID: 21834553 DOI: 10.1021/nl201436b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The ballistic conductance through junctions between multilayer graphene films and several different metals is studied using ab initio calculations within the local density approximation. The system consists of films of up to four graphene layers (Bernal stacking) between metallic electrodes, assuming reasonable metal-graphene epitaxial relationships. For some metals, the conductance decays exponentially with increasing number of layers, while for others the conductance saturates with film thickness. This difference in asymptotic behavior stems from the crystal momentum (mis)match between the bulk Fermi-level states in the electrode and those in the film. In contrast, for sufficiently thin films the bonding between the metal and the adjacent graphene layer dominates, giving a metal dependence for graphene similar to that seen experimentally for single-wall carbon nanotubes. Among the metals considered here, we find Pd to be the best for electrodes to films with up to 4 graphene layers.
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Affiliation(s)
- Marcelo A Kuroda
- IBM T. J. Watson Research Center, Yorktown Heights, NY, United States.
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125
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Zheng Q, Ip WH, Lin X, Yousefi N, Yeung KK, Li Z, Kim JK. Transparent conductive films consisting of ultralarge graphene sheets produced by Langmuir-Blodgett assembly. ACS NANO 2011; 5:6039-51. [PMID: 21692470 DOI: 10.1021/nn2018683] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Monolayer graphene oxide (GO) sheets with sizes ranging from a few to ∼200 μm are synthesized based on a chemical method and are sorted out to obtain four different grades having uniform sizes. Transparent conductive films are produced using the ultralarge graphene oxide (UL-GO) sheets that are deposited layer-by-layer on a substrate using the Langmuir-Blodgett (LB) assembly technique. The density and degree of wrinkling of the UL-GO monolayers are turned from dilute, close-packed flat UL-GO to graphene oxide wrinkles (GOWs) and concentrated graphene oxide wrinkles (CGOWs) by varying the LB processing conditions. The method demonstrated here opens up a new avenue for high-yield fabrication of GOWs or CGOWs that are considered promising materials for hydrogen storage, supercapacitors, and nanomechanical devices. The films produced from UL-GO sheets with a close-packed flat structure exhibit exceptionally high electrical conductivity and transparency after thermal reduction and chemical doping treatments. A remarkable sheet resistance of ∼500 Ω/sq at 90% transparency is obtained, which outperforms the graphene films grown on a Ni substrate by chemical vapor deposition. The technique used in this work to produce transparent conductive UL-GO thin films is facile, inexpensive, and tunable for mass production.
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Affiliation(s)
- Qingbin Zheng
- Department of Mechanical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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126
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Nguyen DD, Tai NH, Chueh YL, Chen SY, Chen YJ, Kuo WS, Chou TW, Hsu CS, Chen LJ. Synthesis of ethanol-soluble few-layer graphene nanosheets for flexible and transparent conducting composite films. NANOTECHNOLOGY 2011; 22:295606. [PMID: 21680964 DOI: 10.1088/0957-4484/22/29/295606] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report a facile method of preparing few-layer graphene nanosheets (FLGs), which can be soluble in ethanol. Atomic force microscopy and high-resolution transmission electron microscopy studies reveal that FLGs have average thicknesses in the range of 2.6-2.8 nm, corresponding to 8-9 layers. A graphene/nafion composite film has a sheet resistance of 9.70 kΩ/sq at the transmittance of 74.5% (at 550 nm) while the nafion film on polyethylene terephthalate has a sheet resistance of 128 kΩ/sq at transmittance of 90.0%. For the cycling/bending test, almost no change in resistance was exhibited when the film was bent at an angle up to 140°, and no obvious deviation in resistance could be found after 100 bending cycles was applied. In addition, an FLGs-poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) composite layer was demonstrated as the effective hole transporting layer to improve the hole transporting ability in an organic photovoltaic device, with which the power conversion efficiency was enhanced from 3.10% to 3.70%. The results demonstrated the promising applications of FLGs on graphene-based electronics, such as transparent electrode and flexible conducting film.
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Affiliation(s)
- D D Nguyen
- Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu 300, Taiwan, Republic of China
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127
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Yu G, Hu L, Vosgueritchian M, Wang H, Xie X, McDonough JR, Cui X, Cui Y, Bao Z. Solution-processed graphene/MnO2 nanostructured textiles for high-performance electrochemical capacitors. NANO LETTERS 2011; 11:2905-11. [PMID: 21667923 DOI: 10.1021/nl2013828] [Citation(s) in RCA: 551] [Impact Index Per Article: 42.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Large scale energy storage system with low cost, high power, and long cycle life is crucial for addressing the energy problem when connected with renewable energy production. To realize grid-scale applications of the energy storage devices, there remain several key issues including the development of low-cost, high-performance materials that are environmentally friendly and compatible with low-temperature and large-scale processing. In this report, we demonstrate that solution-exfoliated graphene nanosheets (∼5 nm thickness) can be conformably coated from solution on three-dimensional, porous textiles support structures for high loading of active electrode materials and to facilitate the access of electrolytes to those materials. With further controlled electrodeposition of pseudocapacitive MnO(2) nanomaterials, the hybrid graphene/MnO(2)-based textile yields high-capacitance performance with specific capacitance up to 315 F/g achieved. Moreover, we have successfully fabricated asymmetric electrochemical capacitors with graphene/MnO(2)-textile as the positive electrode and single-walled carbon nanotubes (SWNTs)-textile as the negative electrode in an aqueous Na(2)SO(4) electrolyte solution. These devices exhibit promising characteristics with a maximum power density of 110 kW/kg, an energy density of 12.5 Wh/kg, and excellent cycling performance of ∼95% capacitance retention over 5000 cycles. Such low-cost, high-performance energy textiles based on solution-processed graphene/MnO(2) hierarchical nanostructures offer great promise in large-scale energy storage device applications.
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Affiliation(s)
- Guihua Yu
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
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128
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Pang S, Hernandez Y, Feng X, Müllen K. Graphene as transparent electrode material for organic electronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2011; 23:2779-95. [PMID: 21520463 DOI: 10.1002/adma.201100304] [Citation(s) in RCA: 314] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 03/01/2011] [Indexed: 05/22/2023]
Affiliation(s)
- Shuping Pang
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
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129
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Nistor RA, Newns DM, Martyna GJ. The role of chemistry in graphene doping for carbon-based electronics. ACS NANO 2011; 5:3096-3103. [PMID: 21391615 DOI: 10.1021/nn200225f] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Graphene forms an important two-dimensional (2D) material class that displays both a high electronic conductivity and optical transparency when doped. Yet, the microscopic origin of the doping mechanism in single sheet or bulk intercalated systems remains unclear. Using large-scale ab initio simulations, we show the graphene surface acts as a catalytic reducing/oxidizing agent, driving the chemical disproportionation of adsorbed dopant layers into charge-transfer complexes which inject majority carriers into the 2D carbon lattice. As pertinent examples, we focus on the molecular SbCl(5) and HNO(3) intercalates, and the solid compound AlCl(3). Identifying the microscopic mechanism for the catalytic action of graphene is important, given the availability of large area graphene sheets, to spur research into new redox reactions for use in science and technology.
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Affiliation(s)
- Razvan A Nistor
- IBM Research Division, T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, New York 10598, USA
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130
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Kuroda MA, Tersoff J, Martyna GJ. Nonlinear screening in multilayer graphene systems. PHYSICAL REVIEW LETTERS 2011; 106:116804. [PMID: 21469888 DOI: 10.1103/physrevlett.106.116804] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Indexed: 05/30/2023]
Abstract
Electrostatic screening in multilayer graphene is highly nonlinear due to the vanishing density of states at the Fermi level. Using a discrete model we study the charge screening normal to the layers. Our model shows a strong charge and temperature dependence and has a simple continuum limit at T=0 for undoped systems. Doped systems can exhibit more complex behavior due to minority-carrier screening. Most importantly we find that the screening length can vary more than an order of magnitude depending on the experimental conditions, reconciling the large range of screening lengths reported in previous experiments. This has important consequences for technological applications of multilayer graphene used in electrodes or transistor channels.
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Affiliation(s)
- Marcelo A Kuroda
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA.
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131
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Hou J, Shao Y, Ellis MW, Moore RB, Yi B. Graphene-based electrochemical energy conversion and storage: fuel cells, supercapacitors and lithium ion batteries. Phys Chem Chem Phys 2011; 13:15384-402. [DOI: 10.1039/c1cp21915d] [Citation(s) in RCA: 443] [Impact Index Per Article: 34.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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132
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Wassei JK, Cha KC, Tung VC, Yang Y, Kaner RB. The effects of thionyl chloride on the properties of graphene and graphene–carbon nanotube composites. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c0jm02910f] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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