• About
    • Login
    View Item 
    •   Institutional Repository Home
    • Electronic Theses and Dissertations
    • Electronic Theses and Dissertations
    • View Item
    •   Institutional Repository Home
    • Electronic Theses and Dissertations
    • Electronic Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of Institutional RepositoryCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    LoginRegister

    A Phosphor-based Light-emitting Diode Using White-light Cadmium Selenide Nanocrystals

    Gosnell, Jonathan David
    : https://etd.library.vanderbilt.edu/etd-03312010-132550
    http://hdl.handle.net/1803/11848
    : 2010-04-16

    Abstract

    White light-emitting diodes (LEDs) have attracted great interest recently due to their capability for higher efficiency and longer lifetimes compared to other current lighting technologies. In pursuit of a white LED that has improved characteristics over commercial white LEDs, the focus of this dissertation is on the optical properties of white-light emitting cadmium selenide (CdSe) nanocrystals. Phosphor-based LEDs typically require an encapsulant to protect the phosphor from heating and photo-oxidation, as well as to inhibit particle aggregation. In this dissertation, a number of encapsulant materials were tested to determine which material would mix well with the nanocrystals in solution before deposition, cure properly as a film, and maintain the optical properties of the CdSe nanocrystals. A biphenylperfluorocylcobutyl (BP-PFCB) polymer performed the best of the encapsulants tested, with over twice the emission intensity of the next best encapsulant as well as a much higher percentage of UV excitation light absorbed at a certain thickness. In addition, several methods to improve the device efficiency of these LEDs were investigated, including experimentally optimizing the LED excitation wavelength, film thickness, and nanocrystal concentration in the film. The optimum device parameters were found to be a 365 nm or 385 nm LED exciting a film of 60-140 μm in thickness with a nanocrystal weight concentration in BP-PFCB of 10%, resulting in a luminous efficacy of 1 lm/W, CIE coordinates of (0.35, 0.37), and a color rendering index (CRI) of 86. Furthermore, while scattering from micron-sized phosphors used in LEDs can cause significant losses, the scattering cross section for ultrasmall CdSe nanocrystals was found to be five orders of magnitude lower than the absorption cross section, thus scattering from nanocrystals can be neglected. Finally, a more accurate approach to determining the nanocrystal concentration of a solution and extinction coefficient was investigated. These results represent the initial steps towards building an ultrasmall CdSe nanocrystal-based, photoluminescent LED, and with further improvements could result in higher quality lighting products.
    Show full item record

    Files in this item

    Icon
    Name:
    GosnellDissertation.pdf
    Size:
    14.85Mb
    Format:
    PDF
    View/Open

    This item appears in the following collection(s):

    • Electronic Theses and Dissertations

    Connect with Vanderbilt Libraries

    Your Vanderbilt

    • Alumni
    • Current Students
    • Faculty & Staff
    • International Students
    • Media
    • Parents & Family
    • Prospective Students
    • Researchers
    • Sports Fans
    • Visitors & Neighbors

    Support the Jean and Alexander Heard Libraries

    Support the Library...Give Now

    Gifts to the Libraries support the learning and research needs of the entire Vanderbilt community. Learn more about giving to the Libraries.

    Become a Friend of the Libraries

    Quick Links

    • Hours
    • About
    • Employment
    • Staff Directory
    • Accessibility Services
    • Contact
    • Vanderbilt Home
    • Privacy Policy