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Exploring Organic Dyes for Grätzel Cells Using Time-Resolved Spectroscopy [Elektronisk resurs]

El-Zohry, Ahmed M. (författare)
Zietz, Burkhard (preses)
Morandeira, Ana (preses)
Hammarström, Leif (preses)
Vauthey, Eric (opponent)
Uppsala universitet Teknisk-naturvetenskapliga vetenskapsområdet (utgivare)
Uppsala Acta Universitatis Upsaliensis 2015
Engelska 84
Serie: Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1651-6214
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  • E-bokAvhandling(Diss. (sammanfattning) Uppsala : Uppsala universitet, 2015)
Sammanfattning Ämnesord
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  • 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 TiO 2 . 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.  

Ämnesord

Natural Sciences  (hsv)
Naturvetenskap  (hsv)
Chemistry with specialization in Physical Chemistry  (uu)
Kemi med inriktning mot fysikalisk kemi  (uu)
Kemi med inriktning mot kemisk fysik  (uu)
Chemistry with specialization in Chemical Physics  (uu)

Indexterm och SAB-rubrik

Laser spectroscopy
DSSCs
DSC
Electron dynamics
Deactivation processes
Isomerization
Twisting
TICT
Quenching by protons
Semiconductor
Electrolyte
Electron injection
Regeneration
Recombination
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