• Login
    View Item 
    •   Home
    • Theses & Dissertations
    • 2015 - Mines Theses & Dissertations
    • View Item
    •   Home
    • Theses & Dissertations
    • 2015 - Mines Theses & Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of Mines RepositoryCommunitiesPublication DateAuthorsTitlesSubjectsThis CollectionPublication DateAuthorsTitlesSubjects

    My Account

    Login

    Mines Links

    Arthur Lakes LibraryColorado School of Mines

    Statistics

    Display Statistics

    Study of thermoelectric properties of graphene materials, A

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    Twombly_mines_0052N_10898.pdf
    Size:
    3.790Mb
    Format:
    PDF
    Download
    Author
    Twombly, Chris
    Advisor
    Wu, Zhigang
    Date issued
    2015
    Keywords
    graphene
    graphene nanomesh
    periodic defected graphene
    thermoelectric
    
    Metadata
    Show full item record
    URI
    https://hdl.handle.net/11124/169997
    Abstract
    Graphene has very beneficial charge transport properties which make it an interesting potential thermoelectric material, but its thermoelectric efficiency is limited by large thermal conductivity. Nanostructuring graphene by incorporating periodic holes in the crystal structure produces graphene nanomesh with reduced thermal conductivity due to increased phonon scattering. The goal of this study was to investigate the thermoelectric properties of graphene nanomeshes and defected graphene using Density Functional Theory and semi-classical Boltzmann Transport Theory. We computed the Seebeck coefficient, electrical conductivity, and the electrical component of thermal conductivity from first principles. We first developed and verified the accuracy of our techniques using silicon. We then examined the properties of silicon nanowires in order to study systems with more complex geometry and to show that nanostructuring can improve thermoelectric properties. Our results agreed closely with previous experimental and theoretical studies of silicon systems. We then employed this suite of methods to study graphene, graphene nanomeshes, and periodically defected graphene. Our calculations for pristine graphene agreed closely with experimental measurements, proving that our methods work well with 2D systems. Our calculations suggest that there is up to a one order of magnitude increase in Seebeck coefficient for graphene nanomeshes compared to pristine graphene. This increase was found to be strongly dependent on a previously predicted geometrically based semimetal to semiconductor transition. We estimated a maximum ZT of 0.15-0.4 for graphene nanomeshes based on a simple scaling law for the thermal conductivity in these systems. The ZT value is strongly dependent on the purity and the quality of the graphene crystal lattice, which affects the relaxation time of charge carriers in these systems. We then studied defected graphene with partial hydrogen passivation and boron-nitride (BN) doping to further demonstrate the importance of the semimetal to semiconductor transition. We concluded that the geometrically based semimetal to semiconductor transition in graphene systems is responsible for improved thermoelectric properties, and helps explain strong disorder based reduction in efficiency reported in previous computational studies. Our study suggests that with further optimization nanostructured graphene could be a potential thermoelectric material.
    Rights
    Copyright of the original work is retained by the author.
    Collections
    2015 - Mines Theses & Dissertations

    entitlement

     
    DSpace software (copyright © 2002 - 2023)  DuraSpace
    Quick Guide | Contact Us
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.