Papers by Keyword: Nanowire

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Authors: H.L. Kwok
Abstract: Quantum efficiency of organic/hybrid solar cells has improved appreciably in recent years and it is useful to re-examine those parameters that reflect the device properties. This is important when there is need to distinguish between improvements associated with materials properties such as domain size and phase separations and improvements linked to external effect such as the inclusion of field enhancement layers. In this work, we reported the evaluation of the “internal” resistivity found in high performance organic/hybrid solar cells based on data reported in the literature. Our observations suggest that in general better device performance is found in devices with higher “internal” resistivity. This includes the case when a hole blocking layer is added. Exceptions to such a rule can be found in solar cells with nanowires in the n-layer and ferroelectric end layers whereby the quantum efficiencies increase beyond the values expected. A simple mathematical model has been put forward to explain the dependence of quantum efficiency on the “internal” resistivity. Overall, lowering of the “internal” resistivity correlates well with degradation in the device performance and can be put in the context of a reduction in the effective diffusion length of the photo-excited carriers. High field and polarization effects by themselves do not affect the “Internal” resistivity.
Authors: Ming Chang, Juti Rani Deka, Chia Hung Lin, Chin Chung Chung
Abstract: One-dimensional (1D) nanostructure such as nanowires (NWs), nanobelts and nanorods have attracted tremendous attention in recent years due to their exceptional micro-structural properties and novel potential applications. In the present investigation, titania (TiO2) nanowires are synthesized by microwave hydrothermal process (MHP) treating TiO2 nano powder with NaOH inside a microwave oven for 5h at 210°C and 350W. The mechanical properties of as synthesized TiO2 nanowires are determined by bending it with a nanomanipulator inside a scanning electron microscope (SEM). Young’s moduli of the nanowires are measured to be approximately 11.870.923GPa.
Authors: Jia Rui Jin, Yuan Zhi Chen, Hui Zhang Guo, Zhen Wei Wang, Dong Liang Peng
Abstract: A non-aqueous synthetic route has been developed for the preparation of uniform Cu nanowires with length up to tens of micrometers. Unlike commonly used one-pot synthesis approach that usually involve a fast reduction of metal precursors in the presence of reducing agents, a continuous-injection approach has been to utilized to control the speed of reaction and the concentration of Cu nuclei. In this approach, copper (II) chloride dihydrate and nickel (II) acetylacetone which are dissolved in oleylamine solutions have been injected into octadecene by a syringe-pump. The as-prepared samples have been characterized by transmission electron microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results show that the products are pure Cu nanowires which have preferred <110> growth directions. The formation mechanism and major influencing factors on the synthesis of Cu nanowires have been discussed.
Authors: Xiao Hui Bai, Dian Zhong Wen
Abstract: This paper implement a nano-structure memristor which based on HP lab memristor.Using electrolyte compose method making Pt nanowires act as nano-structure wires, becoming point contact from liner contact to will enhance quantum effect. Giving key production technology of Pt nanowires,TiO2, TiO2-X thin films.
Authors: Tron Min Chen, Kai Ming Uang, Hao Xiang Chen, Shu Kuo Lin
Abstract: In this study, we report the fabrication and characterization of a novel nanohetero junction structure (NHJ) UV photodetectors (PDs) on flexible polyethylene terephthalate (PET). The ZnO nanowires (NWs) were grown by 2-step hydrothermal growth (HTG) onto p-type nickel oxide (p-NiO) film deposited PET flexible substrate. For enhancing the quality and reliability of the fabricated UV PDs, the PET substrate was treated with a beforehand thermosetting process to refine its toughness and flatness. By switching the illumination UV light “on” and “off”, the fabricated UV PDs biased under-5 V have an on-off current ratio of 16. After over 100 times 90o bend, the transient measurement almost has the same reversibility but on-off current ratio reducing to 10. These results suggest that the proposed n-ZnO-NWs/p-NiO NHJs on PET flexible PET substrate not only have a fairly good response to UV light but also have good endurance within suitable bend. The present optoelectronic UV sensor would provide an effective and simple way for future developments of flexible optoelectronic devices.
Authors: Xiao Ming Lou, Jia Li Huang, Tan Ping Li, Han Xiang Hu, You Xiang Zhang, Ke Li Zhang
Abstract: In this paper, manganite (γ-MnOOH) nanowires have been synthesized, using KMnO4 and CTAB as raw materials, by a hydrothermal method at 180°C for 12h. The samples were characterized by X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), scanning electron microscope (SEM),and thermogravimetric analysis (TG) for the information of crystal form, size, d-spacings, morphology and the weight-loss course. The results showed the manganite nanowires diameter range from 15 nm to 150 nm,length range from 5μm to 20 μm. Moreover, the properties of manganite (γ-MnOOH) nanowires as anode materials for Li-ion batteries had been studied. The first-discharge capacity is 1660 mAh g-1 and corresponds to a consumption of about 5.5 moles of Li per mole of MnOOH, which made this material maybe one of the candidates for the negative materials.
Authors: Xiao Liang Chen, Shun Hong Lin, Jian Ping Ding
Abstract: Due to the relatively high surface-to-volume ratio, the surface effect can be significant for nanoscale materials. A numerical method, which combines surface energy and three-dimensional (3-D) finite element analysis, is proposed to simulate the elastic and plastic deformation of materials and structures at nanoscale. To demonstrate the method is valid and efficient, the free relaxation of single crystalline Cu nanowires is investigated and the numerical results are compared to the atomic simulation results.
Authors: Zue Chin Chang, J.Y. Ling, Chien Chon Chen
Abstract: The fabrication processes of nanomaterials adopt semiconductor manufacturing technology mostly, and restrain from mass production due to high vacuity, expensive equipment, and long cycle time. This research offers a relatively simple and convenient fabrication process to improve the manufacturing technology of nanowires. Starting with aluminum film of high purity, this research utilized anodizing to produce the array nanoporous mold, electrochemical deposition to inject ion-state metal, oxidation-reduction method to obtain metal nanowires, and annealing to result the oxidation of metal nanowires. The influence of substrate and oxidation layers was investigated with respect to parameters such as voltage, current, and time. In order to get the best control of array dispersion, diameters, and depth, the influence of temperature over the process is also investigated. A higher anodizing temperature was utilized to stabilize the fabrication process of the array nanoporous mold. The resulted metal nanowires were analyzed with X-ray diffraction, FE-SEM, and TEM, to inspect the morphology and crystallography. The observations are summarized. (a) The preferred orientation of nickel nanowires being annealed at the 600°C pure nitrogen is NiO(111). (b) As the oxidation temperature rises, NiO in pure oxygen or the atmosphere would transfer into Ni2O3 due to the size effect. Nickel nanowires in pure oxygen could oxidize into Ni2O3 at a lower temperature of 500°C. (c) Nickel nanowires both in pure oxygen and in the atmosphere would transfer stably into Ni2O3 at 900°C.
Authors: Paul K.L. Yu, Edward T. Yu, De Li Wang
Abstract: In this paper we present the concept and demonstration of novel photovoltaic and electro-optic devices, and photoelectrochemical cells based on various semiconductor nanostructures, specifically compound semiconductor quantum wells and nanowires, and the use of plasmonic and related scattering effects from metal or dielectric nanoparticles to increase efficiency of optical absorption. Quantum-well solar cells were fabricated with scattering from metallic or dielectric nanostructures incorporated to direct incident photons into lateral, optically confined paths with high electromagnetic field intensity within relatively thin multiple-quantum-well regions to maximize quantum efficiency of photon absorption. The internal structure of quantum wells in quantum-well solar cells was also analyzed and characterized; the incorporation of a suitable potential step within each quantum well was explored for improvement in power conversion efficiency. Vertical nanowire arrays were engineered to optimize optical confinement within the nanowires, and core-shell heterostructures were employed to achieve broad-spectrum absorption while maintaining high open-circuit voltages. Large linear electro-optic effect is observed in the nanowire arrays. Branched nanowire photoelectrochemical cells were also made and characterized for their spectral incident photon-to-current conversion efficiency. These works have been sponsored by U.S. Department of Energy and National Science Foundation.
Authors: S. Maflin Shaby, A. Vimala Juliet
Abstract: This paper presents a MEMS Piezoresistive pressure sensor which utilizes a circular shaped polysilicon diaphragm with a nanowire to enhance the sensitivity of the pressure sensor. The polysilicon nanowire is fabricated in such a way that it forms a bridge between the circular polysilicon diaphragm and the substrate. The high Piezoresistive effect of Silicon nanowires is used to enhance the sensitivity. A circular polysilicon nanowire piezoresistor was fabricated by means of reactive ion etching. This paper describes the performance analysis, structural design and fabrication of piezoresistive pressure sensor using simulation technique. The polysilicon nanowire pressure sensor has a circular diaphragm of 500nm radius and has a thickness about 10nm. Finite element method (FEM) is adopted to optimize the sensor output and to improve the sensitivity of the circular shaped diaphragm of a polysilicon nanowire Piezoresistive pressure sensor. The best position to place the Polysilicon nanowires to receive maximum stress was also considered during the design process..The fabricated polysilicon nanowire has high sensitivity of about 133 mV/VKPa.
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