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Perez-Hernandez G.,Juarez Autonomous University of Tabasco | Pantoja-Enriquez J.,Research Center y Desarrollo Tecnologico en Energias Renovables | Escobar-Morales B.,Technological Institute of Cancun | Martinez-Hernandez D.,Juarez Autonomous University of Tabasco | And 4 more authors.
Thin Solid Films | Year: 2013

Cadmium sulfide thin-films were deposited on glass slides and SnO 2:F coated glass substrates by chemical bath deposition, sputtering and close-spaced sublimation techniques. The films were studied for the structural and opto-electronic properties after annealing in an ambient identical to that employed in the fabrication of CdTe/CdS devices. Quantum efficiency of the CdTe/CdS solar cells fabricated with CdS buffer films prepared by the three methods were investigated to understand the role of CdS film preparation method on the blue response of the devices. The higher blue response observed for the devices fabricated with chemical bath deposited CdS film is discussed. © 2012 Elsevier B.V. Source


Perez Hernandez G.,Juarez Autonomous University of Tabasco | Pantoja Enriquez J.,Research Center y Desarrollo Tecnologico en Energias Renovables | Ramos-Villegas C.I.,Juarez Autonomous University of Tabasco | Gonzalez-Solano M.,Juarez Autonomous University of Tabasco | And 4 more authors.
Journal of the Marine Biological Association of the United Kingdom | Year: 2013

The dye-sensitized solar cells (DSSC) are a technological and economical alternative to conventional p-n junction solar cells. The DSSC is composed of a transparent conducting electrode (SnO2:F) coated by a porous, nanocrystalline film of n-ZnO to which dye molecules are attached, an organic electrolyte containing a reduction-oxidation couple, and finally a counter-electrode (glass/SnO2:F) coated by a thin film of platinum. The most efficient dyes for DSSCs are based on Ruthenium polypyridyl complexes, related to the high absorption coefficient in the entire visible range and the efficient injection of electrons into the conduction band of ZnO. However, the ruthenium polypyridyl complex contains a heavy metal of relatively high cost, and synthetic routes are complicated with low yields. Moreover, natural dyes in addition to their availability, are cost-effective, non-toxic and biodegradable materials, and can be extracted by simple procedures. In this paper we report the extraction of natural dyes from the stems of mangrove (D1) and tinto (D2) trees as well as from walnut (D3) shell. First, it was necessary to dehydrate the materials, after which extraction was performed using ethanol, water and sodium hydroxide solution. The dyes were characterized using UV-visible and infrared spectroscopy. The analysis of the infrared spectra shows an intense and broad band related to OH bond stretching vibration at 3393, 3442 and 3390 cm-1 for the mangrove tree, tinto tree and walnut shell, respectively. At 1051, 1123 and 1050 cm-1, there was a very strong absorption due to the stretching vibration of CO group, for the mangrove tree, tinto tree and walnut shell, respectively. These results indicate that the functional group for bonding to the ZnO is -OH for these dyes. The results of the U-Vis spectroscopy show that the strongest absorption in the visible region is provided by dyes of the tinto and mangrove trees. The current - voltage curve of a preliminary ZnO-DSSC sensitized with the natural dye of the mangrove tree bark is presented. Copyright © Materials Research Society 2013. Source


Torres-Hernandez J.R.,Juarez Autonomous University of Tabasco | Ramirez-Morales E.,Juarez Autonomous University of Tabasco | Rojas-Blanco L.,Juarez Autonomous University of Tabasco | Pantoja-Enriquez J.,Research Center y Desarrollo Tecnologico en Energias Renovables | And 6 more authors.
Materials Science in Semiconductor Processing | Year: 2015

ZnO and ZnO modified with Cu nanoparticles have been prepared by a simple forced hydrolysis method. The concentration of Cu incorporated in ZnO ranged from 1% to 5% by atomic weight, and the influence of Cu concentration on the physical properties of ZnO and the relation to the photocatalytic performance has been investigated. The prepared ZnO and ZnO:Cu samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy and UV-vis transmittance spectroscopy. The results show that the ZnO nanomaterial was crystalline with the hexagonal wurtzite structure, with the preferential orientation of the grains along the (101) plane. The average grain size for samples with 1-5% Cu was in the range of 11-29 nm. The ZnO nanoparticles annealed at 420 °C showed an increased photocatalytic activity for the decomposition of methylene blue. © 2015 Elsevier Ltd. All rights reserved. Source

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