Design and synthesis of nanocrystal heterostructures for optoelectronic applications
Name
260052074-MIT.pdf
Description
Full printable version
Size
66.57 MB
Format
Adobe PDF
Checksum (MD5)
01831a5e012792772d0a4ccf29dd851d
Author(s)
Halpert, Jonathan E
Advisor(s)
Moungi G. Bawendi.
Date Issued
2008
Publisher
Massachusetts Institute of Technology
Abstract
Colloidal semiconductor nanocrystals can be used for a variety of optoelectronic applications including light emitting devices (LEDs) and photovoltaics. Their narrow emission spectra make them excellent fluorophors for use in red, green and blue emitting organic LEDs and have been shown to achieve external quantum efficiencies as high as 2.7%, 1.8% and 0.4% respectively. Better synthetic methods have produced nanocrystal emitters with higher quantum yield, boosting efficiency, while a better understanding of QD-OLED function has led to improved organic transport materials. These QD-OLED devices can also be redesigned using inorganic hole and electron transport materials to produce inorganic QD-LEDs (QD-ILEDs) with EQE as high as 0.1%. Inorganic transport layers are more robust to solvents and oxygen, and are expected to greatly increase the device lifetime of QD-LEDs over devices employing organic materials. New QD deposition techniques using an inorganic hole transport layer include inkjet printing and Langmuir-Shaeffer dip-coating. Greater synthetic control of the II-VI nanocrystals has also yielded type-II CdSe/CdTe nanobarbells capable of internal exciton separation for photovoltaic applications. Although efficient solar cells using this material could not be produced, the material has given us several insights into the physics and future designs of bulk heterojunction photovoltaic devices. Finally, nanocrystal heterostructures formed using J-aggregate dyes electrostatically bound to QDs, have shown potential for use in LCD or lasing device applications.
Description
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2008.
Vita.
Includes bibliographical references.
Subjects
Chemistry.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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