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

HOOC
S
C
N
N
COO TBA
K77: FULL SUNLIGHT EFFICIENCY: Non-volatile organic solvent electrolyte 8.6-9.5% ; Ionic liquid
electrolyte : 7-7.6 %
N
Ru
N
C
S
Figure 3: left, time dependence of photovoltaic parameters (Jsc, Voc, FF and �) of DSCs based on K77
sensitizer and the binary IL electrolyte varied with the time during the accelerated tests at 80�C in
darkness. right: structure of the K77 dye.
Figure 4: C101 sensitizer Figure 5: Comparison between Si- and DSC cells under various
AM 1.5 light intensity.
Task 4. Encapsulation of DSC
The high transparent, self-cleaning HYFLON-foils from Solvay-Solexis (n=1.34, Figure 6) indeed improve
conversion efficiency and stability behavior of DSC modules as shown in Figure 7. Moreover by
using as antireflection layer on TiO2 glass cell LPI measured 2.5-3% enhanced short circuit current. At
LPI we deposited on a small hyflon foil (7x7 cm 2 ) a homogeneous ITO conductive layer and separately
a non homogeneous layer of SiO2.
OD
1.0
0.8
0.6
0.4
0.2
400
600
800
1000
1200
nm
Figure 6: Transmission of Hyflon-foil
(60 µm, top curve) and
glass slide (1 mm, bottom curve)
1400
1600
1800
2000
Figure 7: IPCE curve of standard
DSC with and without a 60 µm
thick Hyflon encapsulation.
N
N
O
O
Figure 8: Transmittance of encapsulation
materials.
The goal of 6% indicated in the previous report was achieved by using a glass/glass configuration (see
S. Ito et al, Nature Photonics, DOI:10.1038/nphoton.2008.224). The reason for our flexible device low
efficiency is because of the current limitation due to low transparency of PEN/Pt counter electrode
(see Fig. 8). In addition to the screening effect of Redox couple I-/I3- the low viscosity of ionic liquid
electrolyte is responsible for the decrease in the fill factor of the cell at 100 mW/cm 2 irradiation. A polyester/glass
fiber encapsulation was tested in collaboration with CCLab. Fig. 9 shows a 0.5 cm 2 flexible
DSC closed by sandwiching in between two 0.3 mm layers of polyester/glass fiber. No contamination
or damage to the DSC occurred due to this technique. In addition, the combination of polyester/dye/glass
fiber has several advantages as a UV protection layer (figure 10), antireflection layer
(Figure 11), and as a rigidifying coating sealant. Figure 10 shows the UV absorption of this polyester
and emitting the blue light can also serve as a UV protection layer.
Ultralight Photovoltaic Structures, Y. Leterrier, EPFL
194/290
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