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Title page for ETD etd-11282011-120843

Type of Document Master's Thesis
Author Rosson, Teresa Ellen
Author's Email Address teresa.e.tilyou@vanderbilt.edu
URN etd-11282011-120843
Title Fluorescence Enhancement of White-Light Cadmium Selenide Nanocrystals
Degree Master of Science
Department Chemistry
Advisory Committee
Advisor Name Title
Sandra J. Rosenthal Committee Chair
Charles M. Lukehart Committee Member
David W. Wright Committee Member
  • CIE coordinates
  • band gap
  • emission
  • dodecanethiol
  • thiol
  • fluorometer
  • uv-vis
  • hexadecylamine
  • absorption
  • trioctylphosphine oxide
  • dodecylphosphonic acid
Date of Defense 2011-11-28
Availability unrestricted
Advances are being made in lighting technology, as incandescent and fluorescent light bulbs become less efficient compared to solid-state lighting devices, especially light-emitting diodes (LEDs). Cadmium selenide (CdSe) semiconductor nanocrystals are a promising material to use as a light source because of their unique ability to fluoresce different colors of light over the entire visible spectrum, depending on their size. In 2005, Bowers et al. discovered that if CdSe nanocrystals are synthesized to be ultrasmall (~1.5nm in diameter), they emit broad spectrum white light. These white-light nanocrystals offer an alternative to current “white” LEDs because they emit pure white from a single semiconductor material, and they could possibly be manufactured more efficiently than current commercial light bulbs. The drawback to this goal is that the nanocrystal brightness efficiency is only 8-9% immediately after synthesis. Present research is concerned with brightening these nanocrystals, without compromising their white emission, by incorporating various chemicals onto the surface. Here the nanocrystal fluorescence quantum yield has been found to increase with the addition of certain carboxylic acids, most notably with formic acid. The brightest white light that has been measured with this method is 45% efficient—a significant 500% increase from the original nanocrystals and a major step toward commercial applicability. Ultimately, once the efficiency has been sufficiently increased without compromising the balanced white-light emission, the treated nanocrystals could be incorporated onto an LED, leading to an efficient white-light device that is commercially viable and desirable to the consumer.
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