Near Surface Composition and Reactivity of Indium Tin Oxide: An Evaluation Towards Surface Chemical Concepts and Relevance in Titanyl Phthalocyanine Photovoltaic Devices

Persistent Link:
http://hdl.handle.net/10150/195338
Title:
Near Surface Composition and Reactivity of Indium Tin Oxide: An Evaluation Towards Surface Chemical Concepts and Relevance in Titanyl Phthalocyanine Photovoltaic Devices
Author:
Brumbach, Michael T.
Issue Date:
2007
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:
Photovoltaics manufactured using organic materials as a substitute for inorganic materials may provide for cheaper production of solar cells if their efficiencies can be made comparable to existing technologies. Photovoltaic devices are comprised of layered structures where the electrical, chemical, and physical properties at the multiple interfaces play a significant role in the operation of the completed device. This thesis attempts to establish a relationship between interfacial properties and overall device performance by investigation of both the organic/organic heterojunction interface, as well as the interface between the inorganic substrate and the first organic layer with useful insights towards enhancing the efficiency of organic solar cells.It has been proposed that residual chemical species may act as barriers to charge transfer at the interface between the transparent conductor (TCO) and the first organic layer, possibly causing a large contact resistance and leading to reduced device performance. Previous work has investigated the surface of the TCO but no baseline characterization of carbon-free surfaces has previously been given. In this work clean surfaces are investigated to develop a fundamental understanding of the intrinsic spectra such that further analyses of contaminated surfaces can be presented systematically and reproducibly to develop a chemical model of the TCO surface.The energy level offset at the organic/organic heterojunction has been proposed to relate to the maximum potential achievable for a solar cell under illumination, however, few experimental observations have been made where both the interface characterization and device performance are presented. Photovoltaic properties are examined in this work with titanyl phthalocyanine used as a novel donor material for enhancement of spectral absorption and optimization of the open-circuit potential. Characterization of the interface between TiOPc and C60 coupled with characterization of the interface between copper phthalocyanine and C60 shows that the higher ionization potential of TiOPc does correlate to greater open circuit potentials.Examination of photovoltaic behavior using equivalent circuit modeling relates the importance of series resistance and recombination to the homogeneity of the solar cell structure.
Type:
text; Electronic Dissertation
Keywords:
organic photovoltaic; phthalocyanine; indium tin oxide; photoelectron spectroscopy; surfaces and interfaces; TiOPc
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Chemistry; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Armstrong, Neal R.
Committee Chair:
Armstrong, Neal R.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleNear Surface Composition and Reactivity of Indium Tin Oxide: An Evaluation Towards Surface Chemical Concepts and Relevance in Titanyl Phthalocyanine Photovoltaic Devicesen_US
dc.creatorBrumbach, Michael T.en_US
dc.contributor.authorBrumbach, Michael T.en_US
dc.date.issued2007en_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.abstractPhotovoltaics manufactured using organic materials as a substitute for inorganic materials may provide for cheaper production of solar cells if their efficiencies can be made comparable to existing technologies. Photovoltaic devices are comprised of layered structures where the electrical, chemical, and physical properties at the multiple interfaces play a significant role in the operation of the completed device. This thesis attempts to establish a relationship between interfacial properties and overall device performance by investigation of both the organic/organic heterojunction interface, as well as the interface between the inorganic substrate and the first organic layer with useful insights towards enhancing the efficiency of organic solar cells.It has been proposed that residual chemical species may act as barriers to charge transfer at the interface between the transparent conductor (TCO) and the first organic layer, possibly causing a large contact resistance and leading to reduced device performance. Previous work has investigated the surface of the TCO but no baseline characterization of carbon-free surfaces has previously been given. In this work clean surfaces are investigated to develop a fundamental understanding of the intrinsic spectra such that further analyses of contaminated surfaces can be presented systematically and reproducibly to develop a chemical model of the TCO surface.The energy level offset at the organic/organic heterojunction has been proposed to relate to the maximum potential achievable for a solar cell under illumination, however, few experimental observations have been made where both the interface characterization and device performance are presented. Photovoltaic properties are examined in this work with titanyl phthalocyanine used as a novel donor material for enhancement of spectral absorption and optimization of the open-circuit potential. Characterization of the interface between TiOPc and C60 coupled with characterization of the interface between copper phthalocyanine and C60 shows that the higher ionization potential of TiOPc does correlate to greater open circuit potentials.Examination of photovoltaic behavior using equivalent circuit modeling relates the importance of series resistance and recombination to the homogeneity of the solar cell structure.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectorganic photovoltaicen_US
dc.subjectphthalocyanineen_US
dc.subjectindium tin oxideen_US
dc.subjectphotoelectron spectroscopyen_US
dc.subjectsurfaces and interfacesen_US
dc.subjectTiOPcen_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.advisorArmstrong, Neal R.en_US
dc.contributor.chairArmstrong, Neal R.en_US
dc.contributor.committeememberWysocki, Vicki H.en_US
dc.contributor.committeememberPemberton, Jeanne E.en_US
dc.contributor.committeememberZheng, Zhipingen_US
dc.contributor.committeememberLichtenberger, Dennis L.en_US
dc.identifier.proquest2013en_US
dc.identifier.oclc659746605en_US
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.