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dc.contributor.authorZheng, Yilong
dc.contributor.authorJradi, Fadi M.
dc.contributor.authorParker, Timothy C.
dc.contributor.authorBarlow, Stephen
dc.contributor.authorMarder, Seth R.
dc.contributor.authorSaavedra, S. Scott
dc.date.accessioned2017-02-02T22:40:56Z
dc.date.available2017-02-02T22:40:56Z
dc.date.issued2016-12-14
dc.identifier.citationInfluence of Molecular Aggregation on Electron Transfer at the Perylene Diimide/Indium-Tin Oxide Interface 2016, 8 (49):34089 ACS Applied Materials & Interfacesen
dc.identifier.issn1944-8244
dc.identifier.issn1944-8252
dc.identifier.doi10.1021/acsami.6b10731
dc.identifier.urihttp://hdl.handle.net/10150/622363
dc.description.abstractChemisorption of an organic monolayer to tune the surface properties of a transparent conductive oxide (TCO) electrode can improve the performance of organic electronic devices that rely on efficient charge transfer between an organic active layer and a TCO contact. Here, a series of perylene diimides (PDIs) was synthesized and used to study relationships between monolayer structure/properties and electron transfer kinetics at PDI-modified indium-tin oxide (ITO) electrodes. In these PDI molecules, one of the imide substituents is a benzene ring bearing a phosphonic acid (PA) and the other is a bulky aryl group that is twisted out of the plane of the PDI core. The size of the bulky aryl group and the substitution of the benzene ring bearing the PA were both varied, which altered the extent of aggregation when these molecules were absorbed as monolayer films (MLs) on ITO, as revealed by both attenuated total reflectance (ATR) and total internal reflection fluorescence spectra. Polarized ATR measurements indicate that, in these MLs, the long axis of the PDI core is tilted at an angle of 33-42 degrees relative to the surface normal; the tilt angle increased as the degree of bulky substitution increased. Rate constants for electron transfer (k(s,opt)) between these redox-active modifiers and ITO were determined by potential-modulated ATR spectroscopy. As the degree of PDI aggregation was reduced, k(s,opt) declined, which is attributed to a reduction in the lateral electron self-exchange rate between adsorbed PDI molecules, as well as the heterogeneous conductivity of the ITO electrode surface. Photoelectrochemical measurements using a dissolved aluminum phthalocyanine as an electron donor showed that ITO modified with any of these PDIs is a more effective electron-collecting electrode than bare ITO.
dc.description.sponsorshipCenter for Interface Science: Solar-Electric Materials (CIS:SEM), an Energy Frontier Research Center - U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences [DE-SC0001084]; National Science Foundation [DMR-1506504]; Department of the Navy, Office of Naval Research [N00014-14-1-0580/N00014-16-1-2520]en
dc.language.isoenen
dc.publisherAMER CHEMICAL SOCen
dc.relation.urlhttp://pubs.acs.org/doi/abs/10.1021/acsami.6b10731en
dc.rightsCopyright © 2016, American Chemical Society.en
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.subjectperylene diimideen
dc.subjectphosphonic aciden
dc.subjectelectrochemistryen
dc.subjectelectron transferen
dc.subjectindium-tin oxideen
dc.subjectorganic electronicsen
dc.subjectelectron self-exchangeen
dc.subjectpotential-modulated ATR spectroscopyen
dc.titleInfluence of Molecular Aggregation on Electron Transfer at the Perylene Diimide/Indium-Tin Oxide Interfaceen
dc.typeArticleen
dc.contributor.departmentDepartment of Chemistry & Biochemistry, University of Arizonaen
dc.identifier.journalACS Applied Materials & Interfacesen
dc.description.noteNovember 15, 2016; 12 month embargo.en
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en
dc.eprint.versionFinal accepted manuscripten
refterms.dateFOA2017-11-16T00:00:00Z
html.description.abstractChemisorption of an organic monolayer to tune the surface properties of a transparent conductive oxide (TCO) electrode can improve the performance of organic electronic devices that rely on efficient charge transfer between an organic active layer and a TCO contact. Here, a series of perylene diimides (PDIs) was synthesized and used to study relationships between monolayer structure/properties and electron transfer kinetics at PDI-modified indium-tin oxide (ITO) electrodes. In these PDI molecules, one of the imide substituents is a benzene ring bearing a phosphonic acid (PA) and the other is a bulky aryl group that is twisted out of the plane of the PDI core. The size of the bulky aryl group and the substitution of the benzene ring bearing the PA were both varied, which altered the extent of aggregation when these molecules were absorbed as monolayer films (MLs) on ITO, as revealed by both attenuated total reflectance (ATR) and total internal reflection fluorescence spectra. Polarized ATR measurements indicate that, in these MLs, the long axis of the PDI core is tilted at an angle of 33-42 degrees relative to the surface normal; the tilt angle increased as the degree of bulky substitution increased. Rate constants for electron transfer (k(s,opt)) between these redox-active modifiers and ITO were determined by potential-modulated ATR spectroscopy. As the degree of PDI aggregation was reduced, k(s,opt) declined, which is attributed to a reduction in the lateral electron self-exchange rate between adsorbed PDI molecules, as well as the heterogeneous conductivity of the ITO electrode surface. Photoelectrochemical measurements using a dissolved aluminum phthalocyanine as an electron donor showed that ITO modified with any of these PDIs is a more effective electron-collecting electrode than bare ITO.


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