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Bipyridyl cobalt complex mediators in dye-sensitized solar cells

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dc.contributor.authorScott, Michael J., author
dc.contributor.authorElliott, C. Michael, advisor
dc.date.accessioned2024-03-13T20:27:57Z
dc.date.available2024-03-13T20:27:57Z
dc.date.issued2008
dc.description.abstractDye-sensitization of semiconductor substrates allows for efficient charge injection into the semiconductor conduction band. Dye-sensitized solar cells (DSSCs) exploit this for conversion of light into electrical energy. By employing mesoporous TiO2 a significant portion of visible light can be absorbed. The mesoporous TiO2, deposited on a transparent conducting oxide (TCO) medium, constitutes the photoanode of the DSSC. A wide range of materials may be used as a cathode. A redox electrolyte solution completes the cell. Typically, the I-/I3- redox couple has been employed in DSSCs. The use of bipyridyl cobalt complexes allows for tuning of the cell's electrochemistry, exploration of diverse cathode materials, and investigation of mediator solution additives. Cobalt complexes with alkyl, ester, and amide functionalities were considered throughout this body of work. The cobalt complexes were investigated on the basis of time dependence and electrode dependence. The cobalt complexes are stable for at least a period of one week when dissolved in γ-butyrolactone. Gold, carbon and modified TCO cathodes perform well in cells employing the alkyl substituted complex. Gold cathodes alone provide the best performance with cells employing the ester and amide substituted complex. An optically transparent cathode was developed for use in stacked DSSCs, allowing light that is not absorbed by the first DSSC in a stack to be absorbed by a second cell. A spectrally complementary dye in the second cell extends the light absorption to longer wavelengths. Spatial current images were obtained to investigate the local current behavior of cobalt mediated cells. Intentional electrode damage was visualized, and the effects of increased pressure on the cell were discussed. The use of phenothiazine (PTZ) moieties as co-mediators in cobalt mediated DSSCs was investigated. An anionic PTZ salt was most effective at reducing the photo-oxidized sensitizing dye. This PTZ salt enhanced the performance of DSSCs employing the alkyl substituted cobalt complex. Poor electronic coupling and decreased driving force prevents the PTZ salt from enhancing the performance of DSSCs employing the cobalt complexes with withdrawing functionalities.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.identifierETDF_Scott_2008_3321310.pdf
dc.identifier.urihttps://hdl.handle.net/10217/237946
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2000-2019
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.rights.licensePer the terms of a contractual agreement, all use of this item is limited to the non-commercial use of Colorado State University and its authorized users.
dc.subjectcobalt
dc.subjectcobalt complex
dc.subjectdye-sensitized solar cells
dc.subjectredox mediator
dc.subjectrenewable energy
dc.subjectsolar cells
dc.subjectsolar energy
dc.subjectanalytical chemistry
dc.subjectphysical chemistry
dc.subjectenergy
dc.titleBipyridyl cobalt complex mediators in dye-sensitized solar cells
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineChemistry
thesis.degree.grantorColorado State University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (Ph.D.)

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