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

Furthermore, with a good reproducibility over the experiments, this low temperature approach has
allowed us to flirt with the stringent D4 requirement of 12 % cell efficiency since we were able to
reach performance as high as Voc = 765 mV, Jsc = 21.06 mA/cm² and a FF. = 0.731 leading to a
photon-to-electron conversion efficiency at full sun of c.a. 11.9 % and a maximum power of the cell of
12.2 mW/cm² at 600 mV (see Figure 3). The threshold of 12 % is even reached at lower intensity
illumination since 12.2 % is obtained under an incident light intensity of 50.8 mW/cm² (Voc = 746 mV,
Jsc = 10.96 mA/cm², ff = 0.758). This excellent photovoltaic performance face up favorably to the
Sharp champion DSSC cell and also corresponds to a huge step forward of DSSC state of the art.
Photo-current density (mA/cm²)
25
20
15
10
5
0
-5
1 sun
0.5 sun
0.1 sun
Dark
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Photo-voltage (V)
Fig. 3: (J-V) characteristics of C101 dye grafted at 4°C during 16 hours at 1 sun, 0.5 sun, 0.1 sun and
under dark.
3) Introduction of the second generation sensitizers
In parallel to the previous work, we have successfully designed a new ruthenium complex based on a
C101-derived ancillary ligand that contains two thiophene units instead of one (Fig.4).
Fig. 4: Representation of the structure of the C101 dye (on left) and Z991 dye (on right)
Robust DSC, M. Graetzel, EPFL
124/290
14
12
10
8
6
4
2
0
Cell Power (mW/cm²)
4/6