Charge Transport in Organic and Organometallic Molecules: Device Design, Fabrication, and Testing

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  • March 19, 2019
Creator
  • Bruce, Robert
    • Affiliation: College of Arts and Sciences, Department of Chemistry
Abstract
  • Molecular electronics (ME) represents a frontier for electronics. Designing electronic devices at the single molecule level would lead to extremely high density devices, and the organic materials typically used in ME can bring switchable properties and enable formation of transistors at the single molecule level. While promising, potential issues arise from incorporating these organic-based materials and their unique properties into electronic devices. Solutions exist to generate electrical devices with organic materials, but understanding the impacts of these fabrication processes is necessary for their use in practical application settings. The focus of this work is studying unique organic and organometallic materials in molecular electronic device architectures designed toward use in practical electronic settings. Spin-active organometallic complexes – a cobalt bis(dioxylene) based valence tautomer (CoVT), and multi[(porphinato)metal] oligomer wires – are used to build molecular wires and studied in ME settings designed through self-assembly approaches. While the CoVT molecule is shown to actually lose its valence tautomerism when tethered to a surface, the porphyrin wires show metal center dependence on charge transport properties, enabling them to be used in potentially switchable ME and spintronic devices. Alongside this, a variety of soft lithographic techniques are utilized and the effects of their fabrication processes on device output analyzed. Nanotransfer printing (nTP) is tested with basic monolayers, showing in phenylenedithiols lower tunneling attenuation than seen through other electrically identical architectures. We explain the force effects from nTP to be a possible cause and use this as a case study in highlighting the impact architecture can have on monolayer properties. Despite this, porphyrin wires in nTP junctions exhibit near identical electrical properties compared to single molecule measurements, highlighting the technique’s ability to exhibit the electrical properties of more specialized and complex molecules. Other soft lithographic techniques were also highlighted toward designing macroscopically accessible junctions. Nanoindentation, a kinetically-controlled transfer printing (KTP) process, and transfer of graphene via polymer layer are all studied. As a whole, these processes highlight the effects and limitations that are inherent to designing molecular electronic devices, and we discuss the needs for fabrication processes to enable practical electronic and spintronic devices from organic-based materials.
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  • In Copyright
Advisor
  • Moran, Andrew
  • You, Wei
  • Cahoon, James
  • Warren, Scott
  • Dempsey, Jillian
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2015
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  • Chapel Hill, NC
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  • There are no restrictions to this item.
Date uploaded
  • August 25, 2015

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