Electrical, Structural and Compositional Characterization of Interlayer Material and New Active Layers in Organic Solar Cells

Persistent Link:
http://hdl.handle.net/10150/243120
Title:
Electrical, Structural and Compositional Characterization of Interlayer Material and New Active Layers in Organic Solar Cells
Author:
Macech, Mariola Renata
Issue Date:
2012
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.
Embargo:
Release after 21-Aug-2013
Abstract:
This dissertation focuses on the electrical, structural, and compositional characterization of atomic layer deposited ZnO, and the structural characterization of modified titanyl (TiOPc 6 and TiOPc 9) and copper phthalocyanines (Pc 5). All materials studied have application in organic photovoltaic devices, either as an interlayer (ALD ZnO) or as part of the active layer (TiOPcs and Pc 5). The goals of this research are to advance the understanding of defect chemistry and electronic properties of ALD ZnO after exposure to oxygen plasma, Ar+ sputtering, and aryl phosphonic acid modifications, and to understand the relationship between the chemical structure of modified phthalocyanines and their molecular organization.Based on X-ray photoelectron spectroscopy and photoluminescence, it was determined that the predominant defects in as-received ALD ZnO are zinc vacancies mostly located in the top layer of the ZnO film. Oxygen plasma treatment of as-received ALD ZnO changed the predominant defects to oxygen interstitials, which migrated out of the sample when left exposed in air. Phosphonic acid modification of oxygen plasma treated ALD ZnO was found to suppress the migration of oxygen interstitials from the ALD ZnO sample.Ultraviolet photoelectron spectroscopy was used to study the electronic properties of ALD ZnO. It was determined that surface chemistry strongly influences the work function of ALD ZnO. Oxygen plasma treated ALD ZnO showed the highest work function and as-received ALD ZnO the lowest work function. The phosphonic acid modification of ALD ZnO decreased the work function and surface free energy when compared to oxygen plasma treated ALD ZnO. Near edge X-ray absorption fine structure spectroscopy results showed planes of benzyl rings in aryl phosphonic acid modifiers tilted at approximately 30 - 38° with respect to the surface normal.X-ray diffraction studies on modified phthalocyanines powders and thin films were performed to correlate their chemical composition with their crystal structure. It was determined that strong interactions between molecules lead to higher-order lattices (monoclinic or triclinic). However, upon annealing at higher temperatures, higher-order lattices were transformed to columnar phases because of the side chains incorporated into the modified phthalocyanines.
Type:
text; Electronic Dissertation
Keywords:
Chemistry
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Chemistry
Degree Grantor:
University of Arizona
Advisor:
Armstrong, Neal R.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleElectrical, Structural and Compositional Characterization of Interlayer Material and New Active Layers in Organic Solar Cellsen_US
dc.creatorMacech, Mariola Renataen_US
dc.contributor.authorMacech, Mariola Renataen_US
dc.date.issued2012-
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.releaseRelease after 21-Aug-2013en_US
dc.description.abstractThis dissertation focuses on the electrical, structural, and compositional characterization of atomic layer deposited ZnO, and the structural characterization of modified titanyl (TiOPc 6 and TiOPc 9) and copper phthalocyanines (Pc 5). All materials studied have application in organic photovoltaic devices, either as an interlayer (ALD ZnO) or as part of the active layer (TiOPcs and Pc 5). The goals of this research are to advance the understanding of defect chemistry and electronic properties of ALD ZnO after exposure to oxygen plasma, Ar+ sputtering, and aryl phosphonic acid modifications, and to understand the relationship between the chemical structure of modified phthalocyanines and their molecular organization.Based on X-ray photoelectron spectroscopy and photoluminescence, it was determined that the predominant defects in as-received ALD ZnO are zinc vacancies mostly located in the top layer of the ZnO film. Oxygen plasma treatment of as-received ALD ZnO changed the predominant defects to oxygen interstitials, which migrated out of the sample when left exposed in air. Phosphonic acid modification of oxygen plasma treated ALD ZnO was found to suppress the migration of oxygen interstitials from the ALD ZnO sample.Ultraviolet photoelectron spectroscopy was used to study the electronic properties of ALD ZnO. It was determined that surface chemistry strongly influences the work function of ALD ZnO. Oxygen plasma treated ALD ZnO showed the highest work function and as-received ALD ZnO the lowest work function. The phosphonic acid modification of ALD ZnO decreased the work function and surface free energy when compared to oxygen plasma treated ALD ZnO. Near edge X-ray absorption fine structure spectroscopy results showed planes of benzyl rings in aryl phosphonic acid modifiers tilted at approximately 30 - 38° with respect to the surface normal.X-ray diffraction studies on modified phthalocyanines powders and thin films were performed to correlate their chemical composition with their crystal structure. It was determined that strong interactions between molecules lead to higher-order lattices (monoclinic or triclinic). However, upon annealing at higher temperatures, higher-order lattices were transformed to columnar phases because of the side chains incorporated into the modified phthalocyanines.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectChemistryen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorArmstrong, Neal R.en_US
dc.contributor.committeememberSaavedra, S. Scotten_US
dc.contributor.committeememberMonti, Oliver L. A.en_US
dc.contributor.committeememberMiranda, Katrinaen_US
dc.contributor.committeememberArmstrong, Neal R.en_US
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