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Layer Adsorption (layer + adsorption)

Distribution by Scientific Domains
Polymers and Materials Science100%

Kinds of Layer Adsorption

  • ionic layer adsorption
    		•
  • successive ionic layer adsorption
    		•

    Selected Abstracts

    Microstructure, Morphology, and Ultraviolet Emission of Zinc Oxide Nanopolycrystalline Films by the Modified Successive Ionic Layer Adsorption and Reaction Method

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2010
    Daoli Zhang
    Zinc oxide (ZnO) nanopolycrystalline films were successfully prepared by the modified successive ionic layer adsorption and reaction technique, which was based on the alternate immersion of substrate in the alkaline zinc precursor and deionized water. ZnO films were formed through an accumulation of ZnO crystal clusters. The size of the clusters ranged from 200 to 500 nm based on scanning electron micrographic images. Prepared ZnO films exhibited a wurtzite structure, with good microstructure, surface morphology, and optical properties. Ethanolamine was used as a complex reagent, which improved the adsorption of zinc complex with the substrate. Effects of processing parameters on the properties of ZnO nanopolycrystalline films were studied in detail. Intensive and sharp ultraviolet emission peaks at about 400 nm could be observed in the photoluminescence spectra. [source]

    PbS and CdS Quantum Dot-Sensitized Solid-State Solar Cells: "Old Concepts, New Results"

    ADVANCED FUNCTIONAL MATERIALS, Issue 17 2009
    HyoJoong Lee
    Abstract Lead sulfide (PbS) and cadmium sulfide (CdS) quantum dots (QDs) are prepared over mesoporous TiO2 films by a successive ionic layer adsorption and reaction (SILAR) process. These QDs are exploited as a sensitizer in solid-state solar cells with 2,2,,7,7,-tetrakis(N,N -di- p -methoxyphenylamine)-9,9,-spirobifluorene (spiro-OMeTAD) as a hole conductor. High-resolution transmission electron microscopy (TEM) images reveal that PbS QDs of around 3,nm in size are distributed homogeneously over the TiO2 surface and are well separated from each other if prepared under common SILAR deposition conditions. The pore size of the TiO2 films and the deposition medium are found to be very critical in determining the overall performance of the solid-state QD cells. By incorporating promising inorganic QDs (PbS) and an organic hole conductor spiro-OMeTAD into the solid-state cells, it is possible to attain an efficiency of over 1% for PbS-sensitized solid-state cells after some optimizations. The optimized deposition cycle of the SILAR process for PbS QDs has also been confirmed by transient spectroscopic studies on the hole generation of spiro-OMeTAD. In addition, it is established that the PbS QD layer plays a role in mediating the interfacial recombination between the spiro-OMeTAD+ cation and the TiO2 conduction band electron, and that the lifetime of these species can change by around 2 orders of magnitude by varying the number of SILAR cycles used. When a near infrared (NIR)-absorbing zinc carboxyphthalocyanine dye (TT1) is added on top of the PbS-sensitized electrode to obtain a panchromatic response, two signals from each component are observed, which results in an improved efficiency. In particular, when a CdS-sensitized electrode is first prepared, and then co-sensitized with a squarine dye (SQ1), the resulting color change is clearly an addition of each component and the overall efficiencies are also added in a more synergistic way than those in PbS/TT1-modified cells because of favorable charge-transfer energetics. [source]

    Photosensitization of TiO2 Nanostructures with CdS Quantum Dots: Particulate versus Tubular Support Architectures

    ADVANCED FUNCTIONAL MATERIALS, Issue 5 2009
    David R. Baker
    Abstract TiO2 nanotube arrays and particulate films are modified with CdS quantum dots with an aim to tune the response of the photoelectrochemical cell in the visible region. The method of successive ionic layer adsorption and reaction facilitates size control of CdS quantum dots. These CdS nanocrystals, upon excitation with visible light, inject electrons into the TiO2 nanotubes and particles and thus enable their use as photosensitive electrodes. Maximum incident photon to charge carrier efficiency (IPCE) values of 55% and 26% are observed for CdS sensitized TiO2 nanotube and nanoparticulate architectures respectively. The nearly doubling of IPCE observed with the TiO2 nanotube architecture is attributed to the increased efficiency of charge separation and transport of electrons. [source]

    Microstructure, Morphology, and Ultraviolet Emission of Zinc Oxide Nanopolycrystalline Films by the Modified Successive Ionic Layer Adsorption and Reaction Method

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2010
    Daoli Zhang
    Zinc oxide (ZnO) nanopolycrystalline films were successfully prepared by the modified successive ionic layer adsorption and reaction technique, which was based on the alternate immersion of substrate in the alkaline zinc precursor and deionized water. ZnO films were formed through an accumulation of ZnO crystal clusters. The size of the clusters ranged from 200 to 500 nm based on scanning electron micrographic images. Prepared ZnO films exhibited a wurtzite structure, with good microstructure, surface morphology, and optical properties. Ethanolamine was used as a complex reagent, which improved the adsorption of zinc complex with the substrate. Effects of processing parameters on the properties of ZnO nanopolycrystalline films were studied in detail. Intensive and sharp ultraviolet emission peaks at about 400 nm could be observed in the photoluminescence spectra. [source]