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Quantum chemical calculations of the influence of anchor-cum-spacer groups on femtosecond electron transfer times in dye-sensitized semiconductor nanocrystals
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
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2006 (English)In: Journal of Chemical Theory and Computation, Vol. 2, no 2, 441-451 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2006. Vol. 2, no 2, 441-451 p.
URN: urn:nbn:se:uu:diva-94855OAI: oai:DiVA.org:uu-94855DiVA: diva2:168855
Available from: 2006-09-22 Created: 2006-09-22 Last updated: 2009-03-26Bibliographically approved
In thesis
1. Quantum Chemical Modeling of Dye-Sensitized Titanium Dioxide: Ruthenium Polypyridyl and Perylene Dyes, TiO2 Nanoparticles, and Their Interfaces
Open this publication in new window or tab >>Quantum Chemical Modeling of Dye-Sensitized Titanium Dioxide: Ruthenium Polypyridyl and Perylene Dyes, TiO2 Nanoparticles, and Their Interfaces
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Quantum chemical calculations have been used to model dye-sensitized nanostructured titanium dioxide systems that can be used in solar cells for solar energy to electricity conversion. Structural, electronic and spectral properties of isolated dyes and both bare and dye-sensitized TiO2 have been calculated with density functional theory, providing detailed information about both the separate parts and the dye-TiO2 interface.

The connection between the geometry, the ligand field splitting and the lifetime of the triplet metal-to-ligand charge transfer (MLCT) excited state has been explored for a series of ruthenium polypyridyl dyes. Moreover, the relative energetics of MLCT and metal centered triplet excited states have been studied for a number of such systems. It was found that small alterations of the polypyridyl ligands can result in significant changes in ligand field splitting and in the energetics of the triplet states.

Attachment of the dyes to the TiO2 surface is achieved via anchor and spacer groups. The influence of such groups on various properties of the dye and their ability to act as mediators of photo-induced surface electron transfer has been studied. Delocalization of the lowest unoccupied dye orbital onto the spacer and/or anchor group indicates that certain unsaturated groups can mediate electron transfer.

With a combination of methods that enables efficient computations and a scheme for construction of metal oxide clusters, chemical models for bare TiO2 nanocrystals in the 1-2 nm size range have been developed. The electronic structures show well-developed band structures with essentially no electronic band gap defect states.

Atomistic models of the interface between TiO2 nanocrystals and Ru(II)-bis-terpyridine dyes, the so-called N3 dye as well as perylene dyes are reported. Electronic coupling strengths, which provide estimates for the electron injection times, are extracted from the interfacial electronic structure and the lowest electronic excitations are calculated.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2006. 68 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 220
Quantum chemistry, density functional theory, chromophore, nanocrystal, interface, photoexcitation, triplet state, surface electron transfer, electronic coupling strength, Kvantkemi
National Category
Theoretical Chemistry
urn:nbn:se:uu:diva-7141 (URN)91-554-6650-8 (ISBN)
Public defence
2006-10-13, Häggsalen, Ångströmlaboratoriet, Uppsala, 13:15 (English)
Available from: 2006-09-22 Created: 2006-09-22 Last updated: 2013-05-17Bibliographically approved

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