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Title page for ETD etd-12112014-141358


Type of Document Dissertation
Author Ng, Amy
Author's Email Address amyng1287@gmail.com
URN etd-12112014-141358
Title Characterization of nanocrystal-based photovoltaics: electron microscopy & electron beam-induced current via scanning electron microscopy
Degree PhD
Department Chemistry
Advisory Committee
Advisor Name Title
Sandra J. Rosenthal Committee Chair
Charles M. Lukehart Committee Member
David E. Cliffel Committee Member
Stephen J. Pennycook Committee Member
Keywords
  • nanocrystals
  • ebic
  • electron microscopy
  • photovoltaics
Date of Defense 2014-12-09
Availability unrestricted
Abstract
The work presented here is the first of its kind where nanocrystal-based photovoltaics are characterized by directly imaging the electronic properties and correlating them to the structure of the sample. Through electron beam-induced current (EBIC), a finite beam of high energy electrons mimics photons to generate a photoresponse in the device, thus enabling the measurement of the current being generated in a precise region of the specimen. Two different nanocrystal-based architectures were studied in this manner: (1) a hybrid bulk heterojunction composed of CdSe nanorods dispersed in a conductive polymer matrix and (2) a PbS quantum dot depleted-heterojunction device. Both yielded significant results, such as high hole mobility in the case of (1), and changes in the EBIC signature as a result of defects in (2); the electronic shortcomings of the devices believed prior to this work were also confirmed. Another PbS quantum dot-based device was characterized using high resolution elemental mapping; this architecture comprised of titania nanotubes rather than nanoparticles as used in the photovoltaic described in (2). Preliminary work on CdTe thin film solar cells was also conducted as a test bed for higher resolution EBIC.

With EBIC, maps of nanocrystal-based, solid state photovoltaics were collected and analyzed to reveal important information regarding the electronic properties of the devices as well as areas of improvement. As a result of the latter, more efficient solar cell technology can be developed to help meet the energy demands of the global population.

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