Programm Photovoltaik Ausgabe 2009 ... - Bundesamt für Energie BFE

3/3
� Loss analysis: Comparing the results from the numerical simulations of the 2+1D model to the
measured data leads to a quantitative analysis of the loss mechanisms of the energy conversion
process in DSCs. The main loss channels are: optical losses, recombination losses, transport
limitations, and ohmic losses. The ratio between these losses is analyzed for different operating
points of the DSC.
� Graphical user interface: A graphical user interface is developed for the 2+1D model.
National Collaboration
This project features a high degree of multi-disciplinarity. For an accurate modeling of DSCs knowhow
from optics, condensed matter physics, electrochemistry, applied mathematics and numerics has
to be combined. Therefore the Institute of Computational Physics (ICP) at the ZHAW and the Laboratoire
de Photonique et Interfaces (LPI) at EPFL aim for a close collaboration in this project. Since the
first demonstration of a laboratory DSC by B. O’Regan and M. Grätzel at EPFL in 1991 [1], the LPI
has acquired a long standing experience in experimental research on DSCs [2], from which the project
will largely benefit. On the other hand, the ICP has a broad know-how in modeling complex multiphysics
devices, such as fuel cells and organic light-emitting diodes [7]. The project is funded by the
GEBERT RÜF STIFTUNG.
Outlook 2009
Currently the ICP is developing an optical model of the DSC in order to simulate absorption, reflection
losses and the spatially resolved sensitizer excited state generation rate. This optical model is validated
by optical reflection and transmission measurements of the layers that constitute a DSC (glass,
TCO, nanoporous semiconductor film, monolayer of dye, and electrolyte). The measurements are carried
out by the LPI at the EPFL. The optical model forms the first milestone of the project (March
2009).
In a second step, a complete 1D through-plane model of the DSC is formulated. The model is based
on a coupled nonlinear 1D system of partial differential equations (PDEs) to describe the electrochemical
reactions and the transport processes. The system of PDEs is solved by a finite element
method (FEM) using numerical algorithms developed by the ICP [7]. Again the model is validated on
laboratory DSCs by different measurements techniques such as photovoltage and photocurrent response
as a function of light intensity or spectrally resolved quantum efficiency. The 1D through-plane
model is the main milestone to be achieved in August 2009.
Finally, the 1D through-plane model is extended to a time-dependent version to allow for transient
numerical simulations. These simulations are compared to the various time-dependent measurements
available at the LPI, such as transient photovoltage and photocurrent spectroscopy, electrochemical
impedance spectroscopy, and intensity-modulated photoinduced optical absorption spectroscopy. This
third milestone of the project is scheduled for December 2009.
References
[1] B. O'Regan and M. Grätzel: A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films, Nature
353, pp. 737-739, 1991.
[2] M. Grätzel: The advent of mesoscopic injection solar cells. Progress in Photovoltaics: Research and Applications, Vol.
14, pp. 429-442, 2006.
[3] J. Bisquert: Physical electrochemistry of nanostructured devices. Phys. Chem. Chem. Phys. 10, pp. 49-72, 2008.
[4] L. M. Peter: Characterization and Modeling of Dye-Sensitized Solar Cells. J. Phys. Chem C 111, pp. 6601-6612, 2007
[5] J. Schumacher: Numerical simulation of silicon solar cells with novel cell structures. Doktorarbeit (PhD), University
of Konstanz, Germany, 2000. URL: http://www.ub.uni-konstanz.de/kops/volltexte/2001/665/
[6] G. Rothenberger et. al.: A contribution to the optical design of dye-sensitized nanocrystalline solar cells. Solar Energy
Materials and Solar cells 58, pp. 321-336, 1999.
[7] J. Eller, J. Schumacher, G. Sartoris, M. Roos: Computationally efficient simulation of PEM fuel cells and stacks. 5th
Symposium on Fuel Cell Modelling and Experimental Validation, 11th-12th March 2008, Winterthur, Switzerland. URL:
http://www.zhaw.ch/de/engineering/icp/fuel-cell-symposium.html.
129/290
Modeling, simulation and loss analysis of dye-sensitized solar cells, J.O. Schumacher, ZHAW - ICP