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Photoisomerization of the cyanoacrylic acid acceptor group - a potential problem for organic dyes in solar cells
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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2014 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, no 6, 2251-2255 p.Article in journal (Refereed) Published
Abstract [en]

Organic solar cell dyes containing the most common anchoring group, cyanoacrylic acid, are shown to be photolabile and undergo photoisomerization. This may have significant consequences for dye-sensitized solar cells, as isomerisation competes with electron injection and leads to modifications of the dye and surface arrangement.

Place, publisher, year, edition, pages
2014. Vol. 16, no 6, 2251-2255 p.
National Category
Natural Sciences
URN: urn:nbn:se:uu:diva-218969DOI: 10.1039/c3cp54048kISI: 000329926700005OAI: oai:DiVA.org:uu-218969DiVA: diva2:698142
Available from: 2014-02-20 Created: 2014-02-20 Last updated: 2015-11-16Bibliographically approved
In thesis
1. Exploring Organic Dyes for Grätzel Cells Using Time-Resolved Spectroscopy
Open this publication in new window or tab >>Exploring Organic Dyes for Grätzel Cells Using Time-Resolved Spectroscopy
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Grätzel cells or Dye-Sensitized Solar Cells (DSSCs) are considered one of the most promising methods to convert the sun's energy into electricity due to their low cost and simple technology of production. The Grätzel cell is based on a photosensitizer adsorbed on a low band gap semiconductor. The photosensitizer can be a metal complex or an organic dye. Organic dyes can be produced on a large scale resulting in cheaper dyes than complexes based on rare elements. However, the performance of Grätzel cells based on metal-free, organic dyes is not high enough yet. The dye's performance depends primarily on the electron dynamics. The electron dynamics in Grätzel cells includes electron injection, recombination, and regeneration. Different deactivation processes affect the electron dynamics and the cells’ performance.

In this thesis, the electron dynamics was explored by various time-resolved spectroscopic techniques, namely time-correlated single photon counting, streak camera, and femtosecond transient absorption. Using these techniques, new deactivation processes for organic dyes used in DSSCs were uncovered. These processes include photoisomerization, and quenching through complexation with the electrolyte. These deactivation processes affect the performance of organic dyes in Grätzel cells, and should be avoided. For instance, the photoisomerization can compete with the electron injection and produce isomers with unknown performance. Photoisomerization as a general phenomenon in DSSC dyes has not been shown before, but is shown to occur in several organic dyes, among them D149, D102, L0 and L0Br. In addition, D149 forms ground state complexes with the standard iodide/triiodide electrolyte, which directly affect the electron dynamics on TiO2. Also, new dyes were designed with the aim of using ferrocene(s) as intramolecular regenerators, and their dynamics was studied by transient absorption.

This thesis provides deeper insights into some deactivation processes of organic dyes used in DSSCs. New rules for the design of organic dyes, based on these insights, can further improve the efficiency of DSSCs. 

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 84 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1294
Laser spectroscopy, DSSCs, DSC, Electron dynamics, Deactivation processes, Isomerization, Twisting, TICT, Quenching by protons, Semiconductor, Electrolyte, Electron injection, Regeneration, Recombination
National Category
Natural Sciences
Research subject
Chemistry with specialization in Physical Chemistry; Chemistry with specialization in Chemical Physics
urn:nbn:se:uu:diva-263143 (URN)978-91-554-9349-3 (ISBN)
Public defence
2015-11-19, Häggsalen, Ångströmlaboratoriet, Uppsala, 10:15 (English)
Available from: 2015-10-22 Created: 2015-09-27 Last updated: 2015-10-27

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