HOPV12 - Blogs

4 th Hybrid and Organic Photovoltaic Conference -Uppsala 2012 251
C114 - A theoretical study on Zn-porphyrins as potential dyes on ZnO-based dyesensitized
solar cells
Markus Pfau a , Rubén Costa a , Dirk Guldi a , Tim Clark b
a, University of Erlangen, Egerlandstrasse 3, Erlangen, 91058, DE
b, University of Erlangen, CCC, Nägelsbachstrasse 25, 91052 Erlangen, DE
Dye-Sensitized Solar Cells (DSSCs) are a promising source for solar energy conversing
devices. As a matter of fact, a device with 13 % efficiency was recently reported using a
porphyrin with a push-pull character. [1] This device was based on TiO2 photoanode electrodes.
However, ZnO is evolving as an interesting alternative for TiO2, due to higher electron
transport efficiency limiting the recombination current in the individual dyes. [2] Even so
efficiencies as high as 7.5 % were recently reported for ZnO based DSSCs with a N719 dye, [3] up
to today no in depth investigation has been performed on porphyrin based ZnO devices. Thus,
the goal of this study is to show that different linkers binding archetypal Zn-based porphyrins
exert substantial effects on the processes of the device, mainly the electron injection. To this
end, we have performed theoretical assays based on semi-empirical and DFT methods to
model ZnO in combination with the respective porphyrins.
Notable, the different porphyrins give rise to a remarkable impact on the conduction and
valance bands of ZnO. In addition, molecular dynamics show the individual energetic
stabilities and spatial orientations for each type of porphyrin. This information was used to
simulate the electron injection processes and, subsequently, to evaluate the prospect of the
different linkers as integrated component in ZnO-based DSSCs. Indeed, our forefront research
is currently focusing on the most promising linkers in the synthesis of porphyrins and in DSSC
tests.
References
[1] Yella, A.; Lee, H.-W.; Tsao, H. N.; Yi, C.; Chandiran, A. K.; Nazeeruddin, Md.K.; Diau, E. W.-G.; Yeh, C.-Y.;
Zakeeruddin, S. M.; Grätzel, M. "Porphyrin-Sensitized Solar Cells with Cobalt (II/III)–Based Redox Electrolyte Exceed
12 Percent Efficiency". Science 334, 629-634 (2011).
[2] Marczak, R.; Werner, F.; Ahmad, R.; Lobaz, V.; Guldi, D. M.; Peukert, W. "Detailed investigations of ZnO
photoelectrodes preparation for dye sensitized solar cells". Langmuir The Acs Journal Of Surfaces And Colloids 27,
3920-3929 (2011).
[3] Memarian, N.; Concina, I.; Braga, A.; Rozati, S. M.; Vomiero, A.; Sberveglieri, G. "Hierarchically Assembled ZnO
Nanocrystallites for High-Efficiency Dye-Sensitized Solar Cells". Angew. Chem. Int. Ed., 50, 12321–12325 (2011).
© SEFIN 2012