Chan, Yang-Hsiang (2010-05). Applications of Self-assembly for Molecular Electronics, Plasmon Coupling, and Ion Sensing. Doctoral Dissertation. Thesis uri icon

abstract

  • This dissertation focused on the applications of self-assembled monolayers (SAMs) technique for the investigation of molecule based electronics, plasmon coupling between CdSe quantum dots and metal nanoparticles (MNPs), and copper ion detection using enhanced emission of CdSe quantum dots (QDs). The SAMs technique provides an approach to establish a robust, two-dimensional and densely packed structure which can be formed on metal or semiconductor surfaces. This allows for the design of molecular assemblies that can be used to understand the details of molecular conduction by employing various electrical testbeds. In this work, the strategy of molecular assemblies was used to pattern metal nanoparticles on GaAs surfaces, thereby furnishing a platform to explore the interactions between QDs and MNPs. The enhanced emission of CdSe QDs by MNPs was then used as a probe for ultrasensitive, cheap, and rapid copper(II) detection. The study is divided into three main facets. The first one aimed at controlling electron transport behavior through porphyrins on surfaces with an eye toward optoelectronic and light harvesting applications. The binding of the porphyrin molecules to Au surfaces, pre-covered with a dodecanethiol matrix, was characterized by FTIR, XPS, AFM, STM, of. This study has shown that the perfluoro coupling group between the porphyrin macrocycle and the thiol tether may provide a means of controlling the tunneling behavior. The second area of this study focused on the design of a simple platform to examine the coupling between metal nanostructures and quantum dot assemblies. Here we demonstrate that by using a patterned array of Au or Ag nanoparticles on GaAs, plasmon enhanced photoluminescence (PL) can be directly measured and quantified by direct scaling of regions with and without metal nanostructures. The third field presented a simple manner for using the enhanced PL of CdSe QDs as a probe for ultrasensitive Cu2+ ion detection and quantitative analysis. The PL of QDs was enhanced by two processes: first, photobrightening of the material, and second, plasmonic enhancement by coupling with Ag nanoprisms. This strong PL leads to a high sensitivity of the QDs over a wide dynamic range for Cu2+ detection, as Cu2+ efficiently quenches the QD emission.
  • This dissertation focused on the applications of self-assembled monolayers
    (SAMs) technique for the investigation of molecule based electronics, plasmon coupling
    between CdSe quantum dots and metal nanoparticles (MNPs), and copper ion detection
    using enhanced emission of CdSe quantum dots (QDs). The SAMs technique provides
    an approach to establish a robust, two-dimensional and densely packed structure which
    can be formed on metal or semiconductor surfaces. This allows for the design of
    molecular assemblies that can be used to understand the details of molecular conduction
    by employing various electrical testbeds. In this work, the strategy of molecular
    assemblies was used to pattern metal nanoparticles on GaAs surfaces, thereby furnishing
    a platform to explore the interactions between QDs and MNPs. The enhanced emission
    of CdSe QDs by MNPs was then used as a probe for ultrasensitive, cheap, and rapid
    copper(II) detection.
    The study is divided into three main facets. The first one aimed at controlling
    electron transport behavior through porphyrins on surfaces with an eye toward
    optoelectronic and light harvesting applications. The binding of the porphyrin molecules to Au surfaces, pre-covered with a dodecanethiol matrix, was characterized by FTIR,
    XPS, AFM, STM, of. This study has shown that the perfluoro coupling group between
    the porphyrin macrocycle and the thiol tether may provide a means of controlling the
    tunneling behavior.
    The second area of this study focused on the design of a simple platform to
    examine the coupling between metal nanostructures and quantum dot assemblies. Here
    we demonstrate that by using a patterned array of Au or Ag nanoparticles on GaAs,
    plasmon enhanced photoluminescence (PL) can be directly measured and quantified by
    direct scaling of regions with and without metal nanostructures.
    The third field presented a simple manner for using the enhanced PL of CdSe
    QDs as a probe for ultrasensitive Cu2+ ion detection and quantitative analysis. The PL of
    QDs was enhanced by two processes: first, photobrightening of the material, and second,
    plasmonic enhancement by coupling with Ag nanoprisms. This strong PL leads to a high
    sensitivity of the QDs over a wide dynamic range for Cu2+ detection, as Cu2+ efficiently
    quenches the QD emission.

publication date

  • May 2010