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IAP Seminar

15 Nov 2012 by in VorträgeNeu

Dienstag, 20.11.2012 um 16:00 Uhr
Technische Universität Wien,
Institut für Angewandte Physik,
Seminarraum 134A, Turm B (gelbe Leitfarbe), 5. OG
1040 Wien, Wiedner Hauptstraße 8-10
Vortragender: Prof. Ladislav Kavan
J. Heyrovsky Institute of Physical Chemistry, Prague/Czech Republic
Electrodes for Dye-Sensitized Solar Cells: A Case of Titanium
Dioxide and Graphene
The growing world’s demand for electricity, confronted with inherent limitations of fossil and nuclear fuels, point at
renewable resources to be the realistic energetic perspective for the society. Sun is unique source of renewable
energy, providing the requested terawatt power in a global scale.
The dye sensitized solar cell (DSC) is an alternative to Si-based photovoltaics; it is favored by low cost and ease of
fabrication. The generic device is a photoelectrochemical DSC with nanocrystalline TiO2? photoanode, electrolyte
redox mediator and a cathode. The latter is typically a film of Pt nanoparticles on F-doped SnO2? (Pt-FTO) and the
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former is the I3 /I in aprotic electrolyte medium. Design of TiO2? photoanode represents significant challenge for
nanoscience. Recent progress in the field highlighted the (001)-oriented TiO2? (anatase) nanosheet exhibiting larger
open circuit voltage in DSC than the reference (101)-terminated anatase nanocrystals. The voltage enhancement is
attributed to the negative shift of flatband potential for the (001)-face. The back electron transfer is significantly slower
for the (001)-nanosheets compared to the same process on (101)-nanoparticles. This can be rationalized in terms of
titania-surface/dye interaction.
Graphene nanoplatelets (GNP) in the form of optically transparent thin films on FTO are useful as cathode material to
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avoid platinum in DSC cathode. They exhibit good electrocatalytic activity towards I3 /I , particularly in electrolyte
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based on ionic liquids. Recently, the traditional I3 /I mediator was replaced by Co-based redox couples with more
positive redox potentials. The obvious motivation consists in enhancing the voltage of DSC. This strategy allows
demonstration of DSC with 12.3% efficiency, which is the current world record for solar energy conversion in DSC.
GNP exhibit high electrocatalytic activity for a mediator Co(L)2; where L is 6-(1H-pyrazol-1-yl)-2,2’-bipyridine, and
even higher activity for Co(bpy)3
. In the latter case, GNP is clearly outperforming the performance of Pt as
Alle interessierten Kolleginnen und Kollegen sind zu diesem Seminar
(45 min mit anschließender gemeinsamer Diskussion) herzlich eingeladen.
U. Diebold e.h.
H. Störi e.h.


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Topic revision: r1 - 15 Nov 2012, SabrinaMayr

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