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Mostrando ítems 41-60 de 511

    • closedAccess   Diffusion, exclusion, and specific binding in a large channel: A study of OmpF selectivity inversion 

      Alcaraz, Antonio; Nestorovich E.M.; López Peris, María Lidón; García Giménez, Elena; Bezrukov S.M.; Aguilella, Vicente Elsevier (2009)
      We find that moderate cationic selectivity of the general bacterial porin OmpF in sodium and potassium chloride solutions is inversed to anionic selectivity in concentrated solutions of barium, calcium, nickel, and magnesium ...

    • closedAccess   Electron Transport and Recombination in Solid-State Dye Solar Cell with Spiro-OMeTAD as Hole Conductor 

      Fabregat-Santiago, Francisco; Bisquert, Juan; Cevey, Le; Chen, Peter; Wang, Mingkui; Zakeeruddin, Shaik Mohammed; Grätzel, Michael American Chemical Society (2009)
      We show that electron transport mechanisms in TiO2 solid-state dye-sensitized solar cells (SDSCs) with spiro-OMeTAD as hole conductor are similar to those of high-performance DSCs with liquid electrolytes and ionic liquids. ...

    • closedAccess   Electron Transport in Dye-Sensitized Solar Cells Based on ZnO Nanotubes: Evidence for Highly Efficient Charge Collection and Exceptionally Rapid Dynamics 

      Martinson, Alex B. F.; Góes, Márcio Sousa; Fabregat-Santiago, Francisco; Bisquert, Juan; Pellin, Michael J.; Hupp, Joseph T. American Chemical Society (2009)
      Dye-sensitized solar cells based on ordered arrays of polycrystalline ZnO nanotubes, 64 μm in length, are shown to exhibit efficient electron collection over the entire photoanode array length. Electrochemical impedance ...

    • closedAccess   Optical Filter Based on a Spatially Patterned Kinoform Diffractive Lens 

      Mínguez-Vega, Gladys; Mendoza-Yero, Omel; Tajahuerce, Enrique; Lancis, Jesús; Andrés, Pedro Institute of Electrical and Electronics Engineers (IEEE) (2009)
      We demonstrate a compact all-diffractive setup for spectral synthesis. The system is composed of a circularly symmetric mask attached to a kinoform diffractive lens. Following diffraction-based analysis, a Fourier transform ...

    • closedAccess   Trap-limited mobility in space-charge limited current in organic layers 

      Montero Martín, José María; Bisquert, Juan; Garcia-Belmonte, Germà; Barea, Eva M; Bolink, Henk J. Elsevier (2009)
      Space-charge limited current transport in organic devices, relevant to the operation of a range of organic optoelectronic devices, is analyzed in the frequency domain. The classical multiple trapping picture with one ...

    • closedAccess   Relaxation of Photogenerated Carriers in P3HT:PCBM Organic Blends 

      Moehl, Thomas; Kytin, Vladimir G.; Bisquert, Juan; Kunst, Marinus; Bolink, Henk J.; Garcia-Belmonte, Germà Wiley (2009)
      Relaxing in the sunlight. Long time-transient decays of photogenerated carriers in P3HT:PCBM blends for organic solar cells are interpreted in terms of the relaxation of hole carriers in a broad density of states. The ...

    • closedAccess   Ion selectivity of a biological channel at high concentration ratio: insights on small ion diffusion and binding 

      López Peris, María Lidón; Aguilella-Arzo, Marcel; Aguilella, Vicente; Alcaraz, Antonio American Chemical Society (2009)
      The ionic selectivity of the bacterial porin OmpF has been investigated in several chloride salts of alkali metal cations under a wide range of concentration ratios. We report a novel way of studying the several factors ...

    • closedAccess   CdSe quantum dot-sensitized TiO2 electrodes: effect of quantum dot coverage and mode of attachment 

      Guijarro, Néstor; Lana-Villarreal, Teresa; Mora-Sero, Ivan; Bisquert, Juan; Gómez, Roberto American Chemical Society (2009)
      We have investigated the sensitization of nanoporous titanium dioxide by previously synthesized CdSe quantum dots (QDs) protected with trioctylphosphine. Covering the nanoporous TiO2 films with QDs has been achieved using ...

    • closedAccess   Electron Lifetime in Dye-Sensitized Solar Cells: Theory and Interpretation of Measurements 

      Bisquert, Juan; Fabregat-Santiago, Francisco; Mora-Sero, Ivan; Garcia-Belmonte, Germà; Gimenez, Sixto American Chemical Society (2009)
      The electron lifetime τn in dye-sensitized solar cells (DSC) is a central quantity to determine the recombination dynamics in the solar cell. It can be measured by several methods: impedance spectroscopy, IMVS, stepped ...

    • closedAccess   Segmental dynamics in poly(ε-caprolactone)/poly(L-lactide) copolymer networks 

      Sabater Serra, Roser; Escobar Ivirico, Jorge L.; Meseguer Dueñas, José María; Andrio, Andreu; Gomez Ribelles, Jose Luis; Salmerón Sánchez, Manuel Wiley (2009)
      Poly(ε-caprolactone) (PCL) and poly(lactic acid) (PLA) networks were prepared from macromonomer diols functionalized with methacrylic anhydride, which allows one to get self-crosslinkable polymers. Besides, both macromonomers ...

    • closedAccess   Surface Passivation of Nanoporous TiO2 via Atomic Layer Deposition of ZrO2 for Solid-State Dye-Sensitized Solar Cell Applications 

      Li, Tina C.; Góes, Márcio Sousa; Fabregat-Santiago, Francisco; Bisquert, Juan; Bueno, Paulo R.; Prasittichai, Chaiya; Hupp, Joseph T.; Marks, Tobin J. American Chemical Society (2009)
      We report here the utilization of atomic layer deposition to passivate surface trap states in mesoporous TiO2 nanoparticles for solid-state dye-sensitized solar cells based on 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylami ...

    • openAccess   Dielectric saturation of water in a membrane protein channel 

      Aguilella-Arzo, Marcel; Andrio, Andreu; Aguilella, Vicente; Alcaraz, Antonio Royal Society of Chemistry (2009)
      Water molecules in confined geometries like nanopores and biological ion channels exhibit structural and dynamical properties very different from those found in free solution. Protein channels that open aqueous pores ...

    • openAccess   Poincaré-sphere representation of phase-mostly twisted nematic liquid crystal spatial light modulators 

      Durán, Vicente; Clemente Pesudo, Pedro Javier; Martínez-León, Lluís; Climent, Vicent; Lancis, Jesús Institute of Physics (2009)
      We establish necessary conditions in order to design a phase-only wave front modulation system from a liquid crystal display. These conditions determine the dependence of the polarization state of the light emerging from ...

    • openAccess   Phase calibration of spatial light modulators by means of Fresnel images 

      Martínez-León, Lluís; Jaroszewicz, Z.; Kołodziejczyk, A.; Durán, Vicente; Tajahuerce, Enrique; Lancis, Jesús Institute of Physics (2009)
      Reliable application of spatial light modulators (SLMs) as programmable diffractive optical elements requires a thorough calibration. In this paper, we propose a method for calibrating SLMs based on the evaluation of ...

    • openAccess   Impedance spectroscopy of thin-film CdTe/CdS solar cells under varied illumination 

      Proskuryakov, Y. Y.; Durose, K.; Al Turkestani, M. K.; Mora-Sero, Ivan; Garcia-Belmonte, Germà; Fabregat-Santiago, Francisco; Bisquert, Juan; Barrioz, Vincent; Lamb, Dan; Irvine, S. J. C.; Jones, Eurig Wyn American Institute of Physics (2009)
      The electrical properties of CdTe/CdS solar cells grown by metal organic chemical vapor deposition were investigated by a technique of impedance measurements under varied intensity of AM1.5 illumination. A generalized ...

    • openAccess   Determination of gap defect states in organic bulk heterojunction solar cells from capacitance measurements 

      Pérez Boix, Pablo; Garcia-Belmonte, Germà; Muñecas, Udane; Neophytou, Marios; Waldauf, Christoph; Pacios, Roberto American Institute of Physics (2009)
      Energy distributions [density-of-states (DOS)] of defects in the effective band gap of organic bulk heterojunctions are determined by means of capacitance methods. The technique consists of calculating the junction capacitance ...

    • openAccess   Fractal generalized zone plates 

      Mendoza-Yero, Omel; Fernández Alonso, Mercedes; Mínguez-Vega, Gladys; Lancis, Jesús; Climent, Vicent; Monsoriu, Juan A. Optical Society of America (2009)
      The construction of fractal generalized zone plates (FraGZPs) from a set of periodic diffractive optical elements with circular symmetry is proposed. This allows us to increase the number of foci of a conventional fractal ...

    • openAccess   Use of principal states of polarization of a liquid crystal device to achieve a dynamical modulation of broadband beams 

      Durán, Vicente; Clemente Pesudo, Pedro Javier; Lancis, Jesús Optical Society of America (2009)
      A spatially resolved polarization switcher operating over a bandwidth of 200 nm is demonstrated. The system is based on liquid crystal technology and no specific-purpose birefringent element is required. The procedure is ...

    • openAccess   Localized versus delocalized states: Photoluminescence from electrochemically synthesized ZnO nanowires 

      Voss, Tobias; Bekeny, Chegnui; Gutowski, J.; Tena-Zaera, Ramón; Elias, Jamil; Lévy-Clément, Claude; Mora-Sero, Ivan; Bisquert, Juan American Institute of Physics (2009)
      We analyze the near-band-edge photoluminescence of electrochemically deposited ZnO nanowires and directly correlate the photoluminescence properties with the carrier concentration in the nanowires as determined from ...

    • openAccess   Random walk numerical simulation for hopping transport at finite carrier concentrations: diffusion coefficient and transport energy concept 

      González Vázquez, J. P.; Anta, Juan A.; Bisquert, Juan Royal Society of Chemistry (2009)
      The random walk numerical simulation (RWNS) method is used to compute diffusion coefficients for hopping transport in a fully disordered medium at finite carrier concentrations. We use Miller–Abrahams jumping rates and ...