Fundamental and applied studies of organic photovoltaic systems

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dc.contributor Bakker, Martin G.
dc.contributor Szulczewski, Gregory J.
dc.contributor Bonizzoni, Marco
dc.contributor Kung, Patrick
dc.contributor.advisor Pan, Shanlin Hill, Caleb M. 2017-03-01T17:09:49Z 2017-03-01T17:09:49Z 2014
dc.identifier.other u0015_0000001_0001650
dc.identifier.other Hill_alatus_0004D_12079
dc.description Electronic Thesis or Dissertation
dc.description.abstract Presented here are applied and fundamental studies of model organic photovoltaic (OPV) systems. Graphene oxide (GO) nanosheets were investigated as a potential electron acceptor in bulk heterojunction organic solar cells which employed poly[3-hexylthiophene] (P3HT) as an electron donor. GO nanosheets were transferred into organic solution through a surfactant-assisted phase transfer method. Electron transfer from P3HT to GO in solutions and thin films was established through fluorescence spectroscopy. Bulk heterojunction solar cells containing P3HT, P3HT-GO, and P3HT-phenyl-C<sub>61</sub>-butyric acid methyl ester (PCBM, a prototypical elector acceptor employed in polymer solar cells) were constructed and evaluated. Single molecule fluorescence spectroscopy was employed to study charge transfer between conjugated polymers and TiO<sub>2</sub> at the single molecule level. The fluorescence of individual chains of the conjugated polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) at TiO<sub>2</sub> surfaces was shown to exhibit increased intermittent (on/off "blinking") behavior compared to molecules on glass substrates. Single molecule fluorescence excitation anisotropy measurements showed the conformation of the polymer molecules did not differ appreciably between glass and TiO<sub>2</sub> substrates. The similarities in molecular conformation suggest that the observed differences in blinking activity are due to charge transfer between MEH-PPV and TiO<sub>2</sub>, which provides additional pathways between states of high and low fluorescence quantum efficiency. The electrodeposition of individual Ag nanoparticles (NPs), which can be used to enhance light harvesting in organic photovoltaic systems, was studied <italic>in situ</italic> via dark field scattering (DFS) microscopy. The scattering at the surface of an indium tin oxide (ITO) working electrode was measured during a potential sweep. Utilizing Mie scattering theory and high resolution scanning electron microscopy (SEM), the scattering data were used to calculate current-potential curves depicting the electrodeposition of individual Ag NPs. The oxidation of individual presynthesized and electrodeposited Ag NPs was also investigated using fluorescence and DFS microscopies.
dc.format.extent 207 p.
dc.format.medium electronic
dc.format.mimetype application/pdf
dc.language English
dc.language.iso en_US
dc.publisher University of Alabama Libraries
dc.relation.ispartof The University of Alabama Electronic Theses and Dissertations
dc.relation.ispartof The University of Alabama Libraries Digital Collections
dc.relation.hasversion born digital
dc.rights All rights reserved by the author unless otherwise indicated.
dc.subject.other Physical chemistry
dc.subject.other Analytical chemistry
dc.subject.other Materials Science
dc.title Fundamental and applied studies of organic photovoltaic systems
dc.type thesis
dc.type text University of Alabama. Dept. of Chemistry Chemistry The University of Alabama doctoral Ph.D.

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