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2010 MRS Fall Meeting

作者： Cheng, Qian Tang, Jie Ma, Jun Zhang, Han Shinya, Norio Qin, Lu-Chang National Institute for Materials Science 1-2-1 Sengen Tsukuba 305-0047 Japan Doctoral Program in Materials Science and Engineering University of Tsukuba 1-1-1 Tennodai Tsukuba 305-8577 Japan Department of Physics and Astronomy University of North Carolina at Chapel Hill Chapel Hill NC 27599-3255 United States

ISBN: (纸本)9781605112800

Graphene, two-dimensional layers of sp2-bonded carbon, has many unique properties. In this paper, graphene is decorated with flower-like MnO2 nanostructures for the application in energy storage devices. The as-prepared graphene and MnO2 nano-flowers, which were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), were assembled into an asymmetric supercapacitor. The specific capacitance of the graphene electrode reached 245 F/g at a charging current of 1 mA. The MnO2 nano-flowers which consisted of tiny rods with a diameter of less than 10 nm were coated onto the graphene electrodes by electrodeposition. The specific capacitance after the MnO2 deposition is 328 F/g at the charging current of 1 mA with an energy density of 11.4 Wh/kg and power density of 25.8 kW/kg. This work suggests that our graphene-based electrodes can be a promising candidate for high-performance energy storage devices. © 2011 materials Research Society.

关键词： Graphene

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Squaraine donors for high efficiency small molecule solar cells

Squaraine donors for high efficiency small molecule solar ce...

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37th IEEE Photovoltaic Specialists Conference, PVSC 2011

作者： Wei, Guodan Wang, Siyi Xiao, Xin Renshaw, C. Kyle Hall, Lincoln Diev, Vyacheslav V. Thompson, Mark E. Forrest, Stephen R. Department of Materials Science and Engineering University of Michigan Ann Arbor MI United States Department of Chemistry University of Southern California Los Angeles CA United States Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI United States Applied Physics Program University of Michigan Ann Arbor MI United States Department of Physics University of Michigan Ann Arbor MI United States

ISBN: (纸本)9781424499656

It has been a challenge to achieve high efficiency organic photovoltaics (OPV) that absorb long wavelength solar radiation without incurring unacceptable reductions in open circuit voltage (Voc) or charge separation efficiency. Based on the parent structure of the 2, 4-bis[4-(N, N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine (SQ), we have increased V oc using a family of highly near-infrared absorbing SQs, achieving values as high as 0.94 V. These SQ donors are: 2, 4-bis[4-(N-Phenyl-1- naphthylamino)-2,6-dihydroxyphenyl] squaraine (1-NPSQ),2,4-bis[4-(N, N-diphenylamino)-2,6 dihydroxyphenyl] squaraine (DPSQ), 2,4-bis[4-(N, N-diphenylamino)-2,6-dihydroxyphenyl] asymmetric squaraine (DPASQ). The spin-cast SQ, 1-NPSQ, DPSQ and DPASQ donors are then coated with the acceptor C60 to form bulk heterojunction (BHJ) solar cells that take advantage of their exceptionally high absorption coefficient and nanocrystalline morphology to overcome the short diffusion length characteristic of these materials. Combined with a high short-circuit current density (J sc=10.6 mA/cm2) and high fill factor (FF=0.64), the optimized 1-NPSQ/C60 photovoltaic cells with 1-NPSQ annealed at elevated temperature have a power conversion efficiency of ηp as high as 6.0% (correcting for solar mismatch) at 1 sun (AM 1.5G) simulated solar illumination, which to our knowledge is the highest efficiency reported to date for small molecule OPVs. © 2011 IEEE.

关键词： Solar cells

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Resonant plasmon-exciton coupling in zinc oxide quantum well-aluminum nanodisc heterostructure arrays

Resonant plasmon-exciton coupling in zinc oxide quantum well...

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作者： Lawrie, Benjamin Kim, Kyeong-Won Norton, David Mu, Richard Haglund, Richard Interdisciplinary Graduate Program in Materials Science Vanderbilt University Nashville TN 37235 United States Department of Materials Science and Engineering University of Florida Gainesville FL 32611 United States Department of Physics Fisk University Nashville TN 37208 United States Department of Physics and Astronomy Vanderbilt University Nashville TN 37235 United States

The emergence of Fano resonances in the extinction spectra of arrays of aluminum nanodiscs 30-200 nm in diameter deposited on [Zn, Mg]O quantum wells provide the first evidence of strong coupling in zinc oxide heteros... 详细信息

ISBN: (纸本)9781557529107

关键词： Semiconductor quantum wells

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Metamorphic solar cells employing chemical mechanical polishing and MOVPE regrowth

Metamorphic solar cells employing chemical mechanical polish...

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37th IEEE Photovoltaic Specialists Conference, PVSC 2011

作者： Mawst, L.J. Dudley, P. Kirch, J. Kim, T. Ruder, S. Kuech, T.F. Tatavarti, R. Department of Electrical and Computer Engineering University of Wisconsin - Madison 1415 Engineering Dr. Madison WI 53706 United States Materials Science Program University of Wisconsin - Madison 1415 Engineering Dr. Madison WI 53706 United States Department of Chemical and Biological Engineering University of Wisconsin - Madison 1415 Engineering Dr. Madison WI 53706 United States MicroLink Devices Inc. Niles IL United States

ISBN: (纸本)9781424499656

We have investigated the MOVPE growth of InxGa1-xAs metamorphic buffer layer (MBL) structures with a focus on techniques to improve the surface morphology and determine the influence of morphology on subsequently grown single-junction device structures. To improve the surface roughness of the underlying MBL, Chemical-Mechanical Polishing (CMP) is employed and MOVPE regrowth of single-junction (SJ) solar cells on top of the polished surface is performed. AFM image analysis indicates the CMP process is effective in reducing the step-graded InxGa1-xAs MBL surface roughness from ∼7-10 nm (as-grown) to 2.3 nm post CMP. A post-CMP ozone/HF treatment was found to be effective in removing silica residue remaining on the surface from the CMP process, allowing for the growth of films on top of the MBL surface subjected to CMP. Improved short circuit current density (Jsc) and external quantum efficiency (QE) were obtained from SJ (1eV) devices which employ the CMP process compared with those on as-grown MBLs. © 2011 IEEE.

关键词： Chemical mechanical polishing

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Large-Area Industrial-Scale Identification and Quality Control of Graphene

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MRS Online Proceedings Library 2011年第1期1344卷 1-6页

作者： Craig M. Nolen Giovanni Denina Desalegne Teweldebrhan Bir Bhanu Alexander A. Balandin Nano-Device Laboratory Department of Electrical Engineering and Materials Science and Engineering Program Bourns College of Engineering University of California – Riverside Riverside USA Visualization and Intelligent Systems Laboratory Department of Electrical Engineering Bourns College of Engineering University of California – Riverside Riverside USA

A large-area graphene layer identification technique was developed for research and industrial applications. It is based on the analysis of optical microscopy images using computational image processing algorithms. The initial calibration is performed with the micro-Raman spectroscopy. The method can be applied to the wafer-scale graphene samples. The technique has the potential to be the gateway in the development of fully automated statistical process control methods for the next generation thin-film materials used by the semiconductor industry. The proposed technique can be applied to graphene on arbitrary substrates and used for other atomically thin materials.

关键词： electronic material optical properties layered

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Heat conduction properties of graphene: Prospects of thermal management applications

Heat conduction properties of graphene: Prospects of thermal...

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IEEE Symposium on Semiconductor Thermal Measurement and Management (SEMI-THERM)

作者： Alexander A. Balandin Nano-Device Laboratory Department of Electrical Engineering and Materials Science and Engineering Program Bourns College of Engineering University of California Riverside Riverside CA USA

As the electronic industry moves towards few-nanometer-scale CMOS and 3D IC designs thermal management becomes crucially important for achieving high performance and reliability of advanced electronic chips. One approach for mitigating the self-heating problems is finding materials with very high thermal conductivity, which can be integrated with Si ICs or used as fillers in the next generation of the thermal interface materials (TIMs). In 2008, we discovered that graphene reveals extremely high intrinsic thermal conductivity, which can exceed that of bulk graphite. To measure the thermal conductivity of an object with a thickness of just one atomic layer, we developed an original experimental technique and applied it to graphene flake suspended across trenches in Si wafers. In this technique, the micro-Raman spectrometer performed the function of a thermometer measuring the local temperature rise from the shift in the spectral position of the Raman G peak. We explained the fact that the intrinsic thermal conductivity of graphene can be larger than that of graphite by the fundamental difference in the low-energy phonon transport in 2D graphene and 3D graphite. The extremely high thermal conductivity of “free” suspended graphene does not mean that it will be automatically preserved when graphene is incorporated inside semiconductor chips or composite TIMs. Thermal conductivity of graphene layers depends strongly on their geometrical size, coupling to the adjacent substrate or capping layers, edges roughness and defect concentration. I will overview the experimental and theoretical results for the thermal conductivity evolution of the few-layer graphene (FLG) considering two limiting cases of the phonon transport limited by the intrinsic and extrinsic effects. The use of graphene as interconnects and heat spreaders in advanced 2D and 3D computer chips will also be discussed. The last section of the talk will have a description of the data for graphene TIM materials. W

关键词： Thermal conductivity Conductivity materials Three dimensional displays Thermal management of electronics Temperature measurement Thermal engineering

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ZnO Modified High Aspect Ratio Carbon Electrodes for Hydrogen Sensing Applications

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Procedia engineering 2011年 25卷 1669-1672页

作者： Umesh Singh Hyun Ae Lee Young-Chul Byun Amit Kumar Sudipta Seal Hyoungsub Kim Hyoung J. Cho Advanced Materials Processing Analysis Centre (AMPAC) and Department of Mechanical Materials & Aerospace Engineering University of Central Florida Orlando USA School of Advanced Materials Science and Engineering (WCU Program) Sungkyunkwan University Suwon Korea

Design, fabrication, and testing results of a hydrogen gas sensor based on a surface modified high density and high aspect ratio 3-D carbon post microarray are described in this paper. After the conversion of photoresist patterns into carbon electrodes, the increased surface was conformally coated with a metal oxide semiconductor film by atomic layer deposition (ALD). A maximum sensitivity as high as 100 (R air / R hydrogen ) has been observed in the fabricated sensor even in the presence of moisture at low temperature. A fast initial response (90% resistance drop in 30 sec at 3000 ppm hydrogen) of the sensor could be utilized for early leak detection. The methodology of surface modification as well as the test result shows good promise for various chemical sensing devices based on the proposed strategy.

关键词： Hydrogen Gas Sensors MEMS Carbon Atomic Layer Deposition ZnO

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Effect of tunnel shape and support system on stability of a tunnel in a deep coal mine in China

45th US Rock Mechanics / Geomechanics Symposium

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45th US Rock Mechanics / Geomechanics Symposium 2011年

作者： Yu, Z.H. Kulatilake, P.H.S.W. Jiang, F.X. School of Civil and Environmental Engineering University of Science and Technology Beijing Beijing China Geological Engineering Program Department of Materials Science and Engineering University of Arizona Tucson AZ 85721 United States

Stability level of tunnels that exist in an underground mine has a great influence on the safety, production and economic performance of the mine. Ensuring of stability for soft-rock tunnels is an important task for deep coal mines located in high in situ stress conditions. The aim of this study is to investigate the effect of tunnel shape and support pattern on the deformation, failure zone and stability around a tunnel located in a coal rock mass in China and to select an appropriate tunnel shape and a support pattern to provide stable stress-deformation conditions around the tunnel. Using the available information on stratigraphy, geological structures, in situ stress measurements and geo-mechanical properties of intact rock and discontinuity interfaces, a three-dimensional numerical model was built by using FLAC software to simulate the stress conditions around the tunnel in the coal rock mass. Analyses were conducted for several tunnel shapes and rock support patterns. Results obtained for the distribution of failure zones, and stress and displacement fields around the tunnel were compared to select the best tunnel shape and support pattern to achieve the optimum stability conditions. © 2011 ARMA, American Rock Mechanics Association.

关键词： Coal mines

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Thermal Properties of Graphene and Carbon Based materials: Prospects of Thermal Management Applications

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MRS Online Proceedings Library 2011年第1期1344卷 1-11页

作者： Suchismita Ghosh Alexander A. Balandin Intel Corporation Hillsboro U.S.A. Nano-Device Laboratory Electrical Engineering Department and Materials science and Engineering Program University of California Riverside Riverside U.S.A.

In recent years, there has been an increasing interest in thermal properties of materials. This arises mostly from the practical needs of heat removal and thermal management, which have now become critical issues for the continuing progress in electronic and optoelectronic industries. Another motivation for the study of thermal properties at nanoscale is from a fundamental science perspective. Thermal conductivity of different allotropes of carbon materials span a uniquely large range of values with the highest in graphene and carbon nanotube and the lowest in amorphous or disordered carbon. Here we describe the thermal properties of graphene and carbon-based materials and analyze the prospects of applications of carbon materials in thermal management.

关键词： thermal conductivity nanostructure C

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Multifunctional Fiber Solar Cell Based on TiO 2 Composite materials

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MRS Online Proceedings Library 2011年第1期1325卷 85-90页

作者： Adam Rice Seong-Ku Kim Zuki Tanaka Dibya Phuyal Xuan Yang Claire Gu Qibing Pei Bin Chen NASA Ames Research Center Moffett Field USA NASA Research Fellowship Program USA Department of Electrical Engineering University of California USA Department of Materials Science and Engineering University of California USA

The paper present a multimode optical fiber based solar lighting and photovoltaic multifunctional device. TiO2, PbS and conducting polymer poly(3-hexylthiophene) (P3HT) were coated on the optical core surface as active photovoltaic layers, with ITO and LiF/Al electrodes. The guided sunlight in the multi-moded fiber was totally internal reflected depending on the incident angle and the evanescent light mode from scattered radiation of light was absorbed by the active layer to generate the electric current. The optical-electrical behaviors such as the short circuit current, filling factor, and open circuit voltage were studied. Furthermore, optical loss and the evanescent field at the interface between the optical fiber core and ITO electrode thin layer was discussed in relation to the coupling light from the guiding medium to the devices. Comparison studies of chemical and physical thin film coating on optical fibers are discussed. In particular, we obtained in situ growth of quantum dot, composite electrolyte and plasmonic enhancement on TiO2. We have demonstrated waveguide like fiber device with photo current measurements and I-V characterizations. Furthermore, we have optimized the device transmission of visible light through total internal reflection, and PV conversion of evanescent light absorbed by solar active composite materials fabricated around optical fibers.

关键词： composite nanostructure photovoltaic

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