HOPV12 - Blogs

4 th Hybrid and Organic Photovoltaic Conference -Uppsala 2012 172
C54 - Theoretical investigation on drift current in Dye Solar Cell and comparison with
experimental data.
Desiree Gentilini, Alessio Gagliardi, Aldo Di Carlo
University of Rome Tor Vergata, Via del Politecnico 1, Rome, 133, IT
In the last years many theoretical investigations have attempt to explain the interplay and
interconnections among the physical processes governing the functioning of Dye Solar Cell
device, but some aspect on the energy conversion, particularly on the charge transport are not
completely unrevealed.
Here a numerical simulation of the complete cell is presented, where ionic and electronic
transport , electron trapping and electrostatic potential are treated on equal footing.The core
of the model is constituted by steady state drift diffusion equations for each carrier coupled
with continuity and Poisson equations, implemented in the framework of TiberCAD simulation
tool [1].
The Poisson equation for the electrostatic potential is often neglected by many models in
literature because it is generally accepted that the long range electric field are sufficiently
screened by the electrolyte with solar intensity up to one sun [2].
Here we quantify the impact of this assumption both on a theoretical point of view and by
means of a systematical comparison with real cells [3]. The model allows to evaluate electric
field intensity and profile at different working points inside the cell. We show that there is a
non negligible effects in terms of ionic drift current and charge density profiles when a real
exponential distribution of localized energy states under the conduction band edge (Real Traps
Model) is considered. (see Fig. 1.)
Figure 1 Charge density profiles calculated for a typical cell with 10 µm active layer thickness. The conduction band
(black continuous line) and the trapped(dashed black line) electron density are reported.
Non negligible effects on the repartition of the current in drift and diffusion components are
revealed.
Moreover we will show the variation of the electric field at the photoanode/TCO interface
when a non ideal contact is considered.
References
[1] «www.tibercad.org,» [Online].
[2] J. van de Langemaat e A. J. Frank, The Journal of Physical Chemistry, vol. 105, p. 11194, 2001.
[3] D. Gentilini, A. Gagliardi, M. Auf der Maur, L. Vesce, D. D'Ercole, T. M. Brown, A. Reale e A. Di Carlo, «Correlation
between Cell Performance and Physical Transport Parameters in Dye Solar Cells,» The Journal of Physical Chemistry
C, vol. 116, p. 1151–1157, 2012.
© SEFIN 2012