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A Ruthenium Complex–Porphyrin–Fullerene-Linked Molecular Pentad as an Integrative Photosynthetic Model
Department of Molecular Engineering Graduate School of Engineering Kyoto University Nishikyo-ku, Kyoto (Japan).
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
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2017 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 56, no 12, p. 3329-3333Article in journal (Refereed) Published
Abstract [en]

A ruthenium complex, porphyrin sensitizer, fullerene acceptor molecular pentad has been synthesized and a long-lived hole–electron pair was achieved in aqueous solution by photoinduced multistep electron transfer: Upon irradiation by visible light, the excited-state of a zinc porphyrin (1ZnP*) was quenched by fullerene (C60) to afford a radical ion pair, 1,3(ZnP.+-C60.−). This was followed by the subsequent electron transfer from a water oxidation catalyst unit (RuII) to ZnP.+ to give the long-lived charge-separated state, RuIII-ZnP-C60.−, with a lifetime of 14 μs. The ZnP worked as a visible-light-harvesting antenna, while the C60 acted as an excellent electron acceptor. As a consequence, visible-light-driven water oxidation by this integrated photosynthetic model compound was achieved in the presence of sacrificial oxidant and redox mediator.

Place, publisher, year, edition, pages
2017. Vol. 56, no 12, p. 3329-3333
Keywords [en]
artificial photosynthesis, fullerenes, molecular pentads, photoinduced electron transfer, porphyrins, ruthenium
National Category
Physical Chemistry
Identifiers
URN: urn:nbn:se:uu:diva-336548DOI: 10.1002/anie.201612456ISI: 000397329300037OAI: oai:DiVA.org:uu-336548DiVA, id: diva2:1170509
Available from: 2018-01-03 Created: 2018-01-03 Last updated: 2018-03-14Bibliographically approved
In thesis
1. Shining Light on Molecules: Electron Transfer Processes in Model Systems for Solar Energy Conversion Investigated by Transient Absorption Spectroscopy
Open this publication in new window or tab >>Shining Light on Molecules: Electron Transfer Processes in Model Systems for Solar Energy Conversion Investigated by Transient Absorption Spectroscopy
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In the recent years, solar energy conversion has attracted a huge research interest due to the potential application for limiting the greenhouse effect. In many solar cells and solar fuel cells, understanding of charge transfer (CT) and recombination is important for future improvement of the overall efficiency. One important tool for that is transient absorption spectroscopy (TAS).

Mesoporous nickel oxide films were investigated due to their potential application in p-type dye-sensitized solar cells (DSSCs), tandem DSSCs and dye sensitized solar fuel cells (DSSFC:s). Firstly, it was found that the hole generated by band gap excitation is trapped on an ultrafast time scale by Ni3+ states. It was possible to observe a direct signal from the holes by transient mid-IR absorption spectroscopy allowing for direct detection of hole injection and trapping. On a ns time scale, the trapped holes relaxed to much less reactive holes which favored long lived NiO-dye charge separation (CS).

A series of perylene monoimide (PMI) dyes with different anchoring groups was studied. Differences in binding affinity and stability were found. Nevertheless, all PMIs showed ultrafast charge separation and similar recombination kinetics. Furthermore, the effect of MLCT localization of ruthenium polypyridyl complexes was investigated. All those dyes showed slow or no hole injection. At the same time, a self-quenching process was found for all compounds that limited the photoconversion efficiency.

Furthermore, a new core-shell structure of p-type DSSCs was proposed and investigated. Here, the liquid electrolyte was replaced by a layer of TiO2. That system was found to undergo both injection and regeneration of the dye on an ultrafast time scale (below 1 ps). Furthermore, the CS state did not show any decay within 2 ns making this structure interesting for application in DSSCs.

A pentad consisting of a known Ru-based (electro)chemical water oxidation catalyst (WOC) linked to two zinc-porphyrin-fullerene dyads (ZnP-C60) was investigated. The charge transfer processes leading to the first oxidation of the WOC were understood. Low levels of water oxidation were detected in presence of a sacrificial electron acceptor.

The gained understanding of the CT dynamics and recombination processes thus allows new strategies to improve the efficiency in molecular systems for solar energy conversion.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. p. 74
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1645
Keywords
photophysics, photoinduced electron transfer, transient absorption spectroscopy, laser spectroscopy, solar energy conversion, p-type DSSCs, Charge separation, recombination, mesoporous NiO
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-343443 (URN)978-91-513-0273-7 (ISBN)
Public defence
2018-05-04, Siegbahnsalen, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
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Supervisors
Available from: 2018-04-13 Created: 2018-03-14 Last updated: 2018-04-24

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Publisher's full texthttp://dx.doi.org/10.1002/anie.201612456

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Föhlinger, JensPetersson, JonasHammarström, Leif

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