CHARACTERIZATION OF THE SIZE-QUANTIZED ELECTRONIC AND OPTICAL PROPERTIES OF CdSe NANOCRYSTALS FOR APPLICATIONS IN PHOTOCATALYSIS, SOLAR CELLS AND DIFFRACTION GRATINGS

Persistent Link:
http://hdl.handle.net/10150/194710
Title:
CHARACTERIZATION OF THE SIZE-QUANTIZED ELECTRONIC AND OPTICAL PROPERTIES OF CdSe NANOCRYSTALS FOR APPLICATIONS IN PHOTOCATALYSIS, SOLAR CELLS AND DIFFRACTION GRATINGS
Author:
Shallcross, Richard Clayton
Issue Date:
2009
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
This dissertation presents novel applications of ligand-capped II-VI semiconductor nanocrystals (i.e. CdSe and CdTe).Hybrid polymer-nanocrystal thin films were prepared using a bottom-up electrochemical crosslinking method, where thiophene-functionalized CdSe NCs were wired to electron-rich 3,4-dioxy-substituded thiophene polymers. Both nanocomposite and effective monolayer (EML) films were achieved by controlling monomer feed ratios during the crosslinking steps. These hybrid thin films showed enhanced photoelectrochemical current efficiencies with a variety of solution acceptor molecules compared to polymer control films, which was due to sensitization by the CdSe NCs. The electronic structure of the polymer played a critical role in the potential (doping) dependent hole capture efficiency from photoexcited CdSe NCs. Furthermore, photocurrent efficiencies were correlated with nanocrystal size, which was a direct product of frontier orbital energy shifting due to quantum confinement effects.All-inorganic CdTe-CdSe nanocrystal solar cells were fabricated by a facile layer-by-layer procedure. A low-temperature sintering strategy was utilized to electronically couple the nanocrystal thin films, which maintained the individual electronic properties of the nanocrystals. The electrical characteristics of these solar cells displayed predictable trends in open circuit voltage with varying CdSe NC diameter.Novel CdSe NC diffraction gratings were prepared by a facile microcontact molding procedure. These transmission gratings showed exceptionally high diffraction efficiencies that were dependent on optimum grating morphologies and the refractive index contrast provided by the nanocrystals, which was size-dependent. These films also showed promise as coupling gratings for internal reflection elements.
Type:
text; Electronic Dissertation
Keywords:
CdSe; diffraction grating; nanocrystal; photocatalysis; quantum dot; solar cell
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Chemistry; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Armstrong, Neal R.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleCHARACTERIZATION OF THE SIZE-QUANTIZED ELECTRONIC AND OPTICAL PROPERTIES OF CdSe NANOCRYSTALS FOR APPLICATIONS IN PHOTOCATALYSIS, SOLAR CELLS AND DIFFRACTION GRATINGSen_US
dc.creatorShallcross, Richard Claytonen_US
dc.contributor.authorShallcross, Richard Claytonen_US
dc.date.issued2009en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThis dissertation presents novel applications of ligand-capped II-VI semiconductor nanocrystals (i.e. CdSe and CdTe).Hybrid polymer-nanocrystal thin films were prepared using a bottom-up electrochemical crosslinking method, where thiophene-functionalized CdSe NCs were wired to electron-rich 3,4-dioxy-substituded thiophene polymers. Both nanocomposite and effective monolayer (EML) films were achieved by controlling monomer feed ratios during the crosslinking steps. These hybrid thin films showed enhanced photoelectrochemical current efficiencies with a variety of solution acceptor molecules compared to polymer control films, which was due to sensitization by the CdSe NCs. The electronic structure of the polymer played a critical role in the potential (doping) dependent hole capture efficiency from photoexcited CdSe NCs. Furthermore, photocurrent efficiencies were correlated with nanocrystal size, which was a direct product of frontier orbital energy shifting due to quantum confinement effects.All-inorganic CdTe-CdSe nanocrystal solar cells were fabricated by a facile layer-by-layer procedure. A low-temperature sintering strategy was utilized to electronically couple the nanocrystal thin films, which maintained the individual electronic properties of the nanocrystals. The electrical characteristics of these solar cells displayed predictable trends in open circuit voltage with varying CdSe NC diameter.Novel CdSe NC diffraction gratings were prepared by a facile microcontact molding procedure. These transmission gratings showed exceptionally high diffraction efficiencies that were dependent on optimum grating morphologies and the refractive index contrast provided by the nanocrystals, which was size-dependent. These films also showed promise as coupling gratings for internal reflection elements.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectCdSeen_US
dc.subjectdiffraction gratingen_US
dc.subjectnanocrystalen_US
dc.subjectphotocatalysisen_US
dc.subjectquantum doten_US
dc.subjectsolar cellen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairArmstrong, Neal R.en_US
dc.contributor.committeememberPemberton, Jeanne E.en_US
dc.contributor.committeememberPyun, Jeffreyen_US
dc.contributor.committeememberEvans, Dennis H.en_US
dc.identifier.proquest10523en_US
dc.identifier.oclc659752256en_US
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