São Miguel dos Campos, Brazil
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Guedes A.F.S.,Grande Rio University | Guedes V.P.,Nanotechnology Laboratory | Tartari S.,Nanotechnology Laboratory | Souza M.L.,Nanotechnology Laboratory | Cunha I.J.,Federal University of Santa Catarina
WMSCI 2016 - 20th World Multi-Conference on Systemics, Cybernetics and Informatics, Proceedings | Year: 2016

The development of Hybrid Optical Devices, using some flexible optically transparent substrate material and organic semiconductor materials, has been widely utilized by the organic electronic industry, when manufacturing new technological products. The Hybrid Optical Device is constituted by the union of the electrochromic device and the organic solar cell. The flexible organic photovoltaic solar cells, in this hybrid optical device, have been the Poly base (3-hexyl thiophene), P3HT, Phenyl-C61-butyric acid methyl ester, PCBM and Polyaniline, PANI, all being deposited in Indium Tin Oxide, ITO. In addition, the thin film, obtained by the deposition of PANI, and prepared in perchloric acid solution, has been identified through PANI-X1. In the flexible electrochromic device, the Poly base (3,4-ethylenedioxythiophene), PEDOT, has been prepared in Propylene Carbonate, PC, being deposited in Indium Tin Oxide, ITO. Also, both devices have been united by an electrolyte solution prepared with Vanadium Pentoxide, V2O5, Lithium Perchlorate, LiClO4, and Polymethylmethacrylate, PMMA. This device has been characterized through Electrical Measurements, such as UV-Vis Spectroscopy and Scanning Electron Microscopy (SEM). Thus, the result obtained through electrical measurements has demonstrated that the flexible organic photovoltaic solar cell presented the characteristic curve of standard solar cell after spin-coating and electrodeposition. Accordingly, the results obtained with optical and electrical characterization have revealed that the electrochromic device demonstrated some change in optical absorption, when subjected to some voltage difference. Moreover, the inclusion of the V2O5/PANI-X1 layer reduced the effects of degradation that this hybrid organic device caused, that is, solar irradiation. Studies on Scanning Electron Microscopy (SEM) have found out that the surface of V2O5/PANI-X1 layers can be strongly conditioned by the surface morphology of the dielectric.


Guedes A.F.S.,Nanotechnology Laboratory | Guedes V.P.,Nanotechnology Laboratory | Souza M.L.,Nanotechnology Laboratory | Tartari S.,Nanotechnology Laboratory | Cunha I.J.,Federal University of Santa Catarina
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Flexible organic photovoltaic solar cells have drawn intense attention due to their advantages over competing solar cell technologies. The method utilized to deposit as well as to integrate solutions and processed materials, manufacturing organic solar cells by the Electrodeposition System, has been presented in this research. In addition, we have demonstrated a successful integration of a process for manufacturing the flexible organic solar cell prototype and we have discussed on the factors that make this process possible. The maximum process temperature was 120°C, which corresponds to the baking of the active polymeric layer. Moreover, the new process of the Electrodeposition of complementary active layer is based on the application of voltage versus time in order to obtain a homogeneous layer with thin film. This thin film was not only obtained by the electrodeposition of PANI-X1 on P3HT/PCBM Blend, but also prepared in perchloric acid solution. Furthermore, these flexible organic photovoltaic solar cells presented power conversion efficiency of 12% and the inclusion of the PANI-X1 layer reduced the effects of degradation on these organic photovoltaic panels induced by solar irradiation. Thus, in the Scanning Electron Microscopy (SEM), these studies have revealed that the surface of PANI-X1 layers is strongly conditioned by the dielectric surface morphology. © 2015 SPIE.


Yan J.,Nanotechnology Laboratory | Yan J.,State University of New York at Buffalo | Liu X.,State University of New York at Buffalo | Yao M.,State University of New York at Buffalo | And 4 more authors.
Chemistry of Materials | Year: 2015

Lithium-sulfur (Li-S) batteries suffer from major problems including poor cycle performance and low efficiency, mainly due to the high solubility of intermediate polysulfides and their side-reactions with the Li-anode. Here, we report the development of advanced, multilayered, sulfur cathodes composed of alternately arranged, negatively charged S-carbon nanotube layers and positively charged S-polyaniline layers that effectively immobilize polysulfides and reduce polysulfide migration onto the Li-anode. The use of a layer-by-layer nanoassembly technique leads to a binder-free, three-dimensional porous cathode via electrostatic attraction and enables the fabrication of Li-S cells with remarkably improved performance including a long cycle life exceeding 600 cycles and a high Coulombic efficiency of 97.5% at the 1 C rate. Moreover, these Li-S cells have presented a high-rate response up to 2.5 C with high sulfur utilization (a reversible capacity of 1100 mAhg-1, 900 mAhg-1, 700 mAhg-1, and 450 mAhg-1 of sulfur at 0.3, 0.6, 1, and 2.5 C rates, respectively). The results provide important progress toward the understanding of the role of multilayered cathodes and the realization of high-efficiency and long-term service life for Li-S batteries. © 2015 American Chemical Society.


News Article | April 23, 2014
Site: www.techtimes.com

U.S. researchers say they've used carbon structures just one atom thick to develop high-performance, low-cost energy-storing ultracapacitors. Combining two different carbon nanostructures possessing complementary properties -- single-walled nanotubes and graphene flakes -- yielded capacitors capable of containing large quantities of energy that can be quickly released to provide a power surge, the researchers at George Washington University say. Such ultracapacitors may provide increased performance in handheld electronics like smartphones and tablets, in electric vehicles, audio systems and other applications, they say. Excellent electronic, mechanical and thermal properties make both graphene and single-walled nanotubes attractive candidates for ultracapacitors, lead researcher Jian Li says; the trick was in bringing them together. Although both materials had been studied singly, few efforts had been made to combine them, Li's colleague Michael Keidar says. "In our lab we developed an approach by which we can obtain both single-walled carbon nanotubes and graphene, so we came up with the idea to take advantage of the two promising carbon nanomaterials together," he says. Writing in the Journal of Applied Physics, the researchers describe how they combine the two different nanostructures to create ink capable of being rolled onto paper, a normal separator used in current capacitor designs. The resulting specific capacitance -- defined as the energy performance of the capacitor compared with its weight -- was as much as three times that of a capacitor made from the carbon nanotubes by themselves, they reported. While the graphene flakes contribute good conductivity and a large surface area, the nanotubes hold the structure tougher in a uniformly spaced network, Li explained. The carbon nanotubes act as reinforcing bars, making the single-atom graphene flakes much easier work with. The resulting capacitor is inexpensive, since the desirable mix of nanostructures is simple to create in large amounts. The researchers said they were able to synthesize the graphene flakes and nanotubes simultaneously by vaporizing a hollow graphite rod filled with metallic catalyst powder with an electric arc. In addition to being cheap to produce, because the ultracapacitor is light and small it will lead to ever smaller and more efficient electronic devices, they researchers said. The research was conducted in the Micro-propulsion and Nanotechnology Laboratory at George Washington University.


Venkata Ramana M.,Nanotechnology Laboratory | Venkata Ramana M.,Sri Krishnadevaraya University | Ramamanohar Reddy N.,Nanotechnology Laboratory | Siva Kumar K.V.,Nanotechnology Laboratory
Physics Research International | Year: 2012

Two series of NiMgCuZn ferrites, that is, (1) Ni x Mg 0.6-x Cu 0.1Zn 0.3Fe 2O 4 and sample G: Ni 0.3Mg 0.3y Cu 0.1Zn 0.5y Fe 2O 4 with x = 0.0, 0.1, 0.2, 0.3 and (2) Ni xMg 0.6-xCu 0.1Zn 0.3Fe 2O 4 with y = 0.0, 0.1, 0.2 were synthesized and prepared by conventional ceramic double-sintering process and to use them as core materials for microinductor applications. The formation of single phase was confirmed by X-ray diffraction. The temperature and compositional variation of DC, AC electrical conductivities () and thermoelectric power () were studied on these two series of polycrystalline ferrospinels. The studies were carried out in wide range of temperature from 30 to 350°C. On the basis of thermoelectric study, the ferrites under present work were found to be shown as n-type and p-type transition. The electrical conduction in these ferrospinels is explained in the light of polaron hopping mechanism. These ferrite compositions have been developed for their use as core materials for microinductor applications. © 2012 M. Venkata Ramana et al.


Vadivelan V.,Bharathiar University | Chandar Shekar B.,Nanotechnology Laboratory
Springer Proceedings in Physics | Year: 2015

Visible spectrum of solar light concentration on wavelength depended solar cell is to enhance the diffraction efficiency of the solar cell is our prime aim. Initial step of successful recording of high diffraction efficiency and good visible transmission holographic optical element were recorded. For this, we used ultra fine grain visible wavelength responsive silver halide holographic emulsion from Ultimate holography. The novelty of this work is three different laser sources of 442, 532 and 633 nm were used to record a single holographic transmission lens by using multiplex technique. The detail study of the holographic optical element recording is explained. © Springer India 2015.


Salem N.M.,University of Jordan | Albanna L.S.,University of Jordan | Awwad A.M.,Nanotechnology Laboratory
Environmental Nanotechnology, Monitoring and Management | Year: 2016

Sulfur nanoparticles (SNPs) have been successfully prepared from sodium thiosulfate in the presence of Punica granatum peels aqueous extract at room temperature. The resulting sulfur nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS). Highly crystalline synthesized sulfur nanoparticles exhibiting high purity, spherical shape with average particle size of about 50 nm applied at a rate of 100 ppm, 200 ppm, and 300 ppm as foliar spray for tomato leaves. The obtained results revealed that the foliar spraying tomato leaves with 200 ppm sulfur nanoparticles are very beneficial to plant growth and produced healthy plant with greener leaves and high quality of tomato fruits compared with control. © 2016 Elsevier B.V.


Prakash T.,Nanotechnology Laboratory | Arunkumar T.,Solar Laboratory | Raj D.S.,Nanotechnology Laboratory | Jayaprakash R.,Nanotechnology Laboratory
Physics Procedia | Year: 2013

This paper presents the synthesis of CdO nanocomposites in chemical precipitation method. This article reports the formation of different morphologies of CdO nanocomposites with Polyethylene glycol (PEG) surfactant. This technique emphasizes the less consumption of time for synthesizing nano powder with smaller particle size. This route for preparing CdO is simple and cost-effective method. CdO nanocomposites were characterized by X-ray powder diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), TEM measurements, Scanning electron microscope (SEM), Energy dispersive spectrum (EDS) and Electrical resistance. The particle size extracted from XRD patterns, were around 30 nm. The particle size obtained from TEM image is will consistent with XRD pattern. Analytical potential of these nanocomposites has been used to determine the trace levels of polycyclic aromatic compounds in river waters. © 2013 The Authors.


Lee J.-C.,Nanotechnology Laboratory | Lee D.-W.,Nanotechnology Laboratory
Microelectronic Engineering | Year: 2010

This paper presents a novel design of tactile sensing arrays with integrated strain gauges for the measurement of contact force. Surface stress or strain changes on the sensor area due to applied force are measured by the encapsulated Au gauges. The fabricated tactile sensors are highly flexible and durable so that they can conform to more complex surfaces without damaging the skin structure and the metal interconnects on the sensing array. The experimental results show the output characteristics are linear with contact force from 0 to 700 gf and a sensitivity of 3%/100 gf within the full scale range of 700 gf. The effect of electrode structure and position on the enhancement of sensitivity are also numerically simulated by a finite element method and verified experimentally. The measured tactile sensors are robust enough for direct contact with human and contaminants without undue care. © 2009 Elsevier B.V. All rights reserved.


Varadarajan V.,Bharathiar University | Bellan C.S.,Nanotechnology Laboratory
2015 2nd International Conference on Opto-Electronics and Applied Optics: Advances in Optical Sciences and Engineering II, IEM OPTRONIX 2015 | Year: 2015

Holography has been utilized for fabrication of optical elements in Silver halide photosensitive emulsion. The main drawback of transmission phase holograms in silver halide emulsion is getting darkens or discolor over the period of time, whenexposed to the ambient light, known as print-out effect. Hence this is unsuitable for out-door applications. In this study, holographic optical elements were fabricated in commercially available silver halide fine grain emulsion, almost completely controlled the darkening or discoloring effect by new chemical technique and it is practically examined by three different testing methods. Fabricated transmission phase holographic lenses have unique property of diffracting, focusing and concentrating of particularwavelength solar spectrumon wavelength dependable solar cells. © 2015 IEEE.

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