HOPV12 - Blogs

4 th Hybrid and Organic Photovoltaic Conference -Uppsala 2012 150
C39 - Carbon nanomaterials as flexible dye solar cell counter electrodes
Kerttu Aitola a , Maryam Borghei a , Antti Kaskela a , Albert Nasibulin a , Esko Kauppinen a , Peter
Lund a , Virginia Ruiz b , Janne Halme a
a, Aalto University School of Science, P.O.Box 15100, Aalto, 00076, Finland
b, CIDETEK-IK4 - Centre for Electrochemical Technologies, Paseo Miramón 196, E-20009 Donostia-San Sebastián, Spain
The dye solar cell (DSC) can be manufactured cost-effectively in the industrial scale by rollto-roll
deposition techniques, but for those the active materials and substrates have to be
flexible. We tested several carbon nanomaterials and their composites as DSC counter
electrodes (CE) and compared them in terms of their flexibility, conductivity, catalytic
performance, thickness and transparency (1,2). The tested materials were thin,
semitransparent single-walled carbon nanotube (SWCNT) random network film on plain plastic
(polyethylene terephthalate, PET), vertically aligned multi-walled carbon nanotube (MWCNT)
“forest” film on quartz and Inconel steel, carbon nanoparticle composite film on indium tin
oxide-PET (ITO-PET) and SWCNT-conductive polymer composite film on plain PET substrate.
The catalytic performance of the pristine SWCNT and MWCNT films was only modest
toward the triiodide reduction reaction of the DSC CE. The SWCNT film had to be relatively
thick (10 % transparent) to obtain sufficient conductivity, and in the MWCNT film the lateral
conductivity had to be ensured with a metal layer. The carbon nanoparticle composite had to
be very thick to obtain sufficient catalytic performance, nevertheless an additional conductive
layer was needed.
The SWCNT film was however the most flexible of the studied films, it offered the best
potential for (semi)transparency and it could be deposited with an easy press-transfer method.
Therefore it was investigated whether its catalytic performance could be improved, and
conductive poly(3,4-ethylenedioxythiophene) (PEDOT) was electrochemically deposited on a
10 % transparent SWCNT film (2). The resulting PEDOT-SWCNT film outperformed sputtered
platinum on ITO-PET as catalyst, as well as electrochemically deposited PEDOT on ITO-PET. It
was observed that the reason for the superior catalytic performance was the fact that the
porous SWCNT film provided a high-surface area platform for the PEDOT nucleation and
growth, thus maximizing the composite catalyst film interfacial area.
It was concluded that the SWCNT network film is an interesting potentially cheap and
flexible alternative material for the DSC CE, but for the iodide/triiodide redox couple its
catalytic performance has to be improved with e.g. PEDOT polymer.
References
[1] Aitola, K.; Halme, J.; Halonen, N.; Kaskela, A.; Toivola, M.; Nasibulin, A.G.; Kordás, K.; Tóth, G.; Kauppinen, E.I.;
Lund, P.D. "Comparison of dye solar cell counter electrodes based on different carbon nanostructures". Thin Solid
Films, 519, 8125-8134 (2011).
[2] Aitola, K.; Borghei, M.; Kaskela, A.; Kemppainen, E.; Nasibulin, A.G.; Kauppinen, E.I.; Lund, P.D.; Ruiz, V.; Halme,
J. "Flexible metal-free counter electrode for dye solar cells based on conductive polymer and carbon nanotubes".
Submitted.
© SEFIN 2012