Page 226 - Mirjam-Theelen-Degradation-of-CIGS-solar-cells
P. 226
Chapter 7
200 200
Non -degraded 150 Non -degraded
Current density (mA/cm 2 ) 100 299K Current density (mA/cm 2 ) 100 260K
Alkali-rich
Alkali-poor
150
Illumination
Illumination
50
50
0 105K 0 105K
0 500 1000 Voltage (mV) 0 500 1000 Voltage (mV)
-50 -50
200 200
165 h degraded 150 165 h degraded
Alkali-rich
Alkali-poor
Current density (mA/cm 2 ) 100 301K Current density (mA/cm 2 ) 100 264K
150
Illumination
Illumination
50
50
107K
106K
0
0 500 1000 Voltage (mV) 0 0 500 1000 Voltage (mV)
-50 -50
Figure 7.8
Current-voltage curves at different temperatures between 100 and 300/260K for the non-degraded CIGS solar cells and solar
cells degraded for 165 hours with barrier (purple) and without barrier (blue) taken under illumination.
seem to prevent the formation of decent solar cell, as is shown in among others Table
7.1. The occurrence of a kink was not observed in the IV(T) spectra of the alkali-poor
sample under illumination. Both samples did also not show a kink in darkness.
After 165 hours of degradation, the kink could still be found for the alkali-rich sample
under illumination. For this specific sample, the impact of degradation seemed
reasonably small, which is surprising since in-situ IV measurements indicated that
o
almost half of the efficiency at 107 C has disappeared. However, at lower temperatures,
the relative loss of efficiency might have been smaller. It can be expected that other
samples, which are more degraded, show more modifications in the curves.
After degradation, the alkali-poor sample did also demonstrate the appearance of a
kink in the illuminated IV curves starting for temperatures as high as ~250K. This was
surprising, since this sample did not show large changes in their electrical parameters
due to damp heat illumination exposure. This kink is still present after 365 hours
degradation (not depicted). The IV(T) of samples degraded for more than 365 hours
were not measured.
In darkness, the exposure to damp heat and illumination did not lead to the appearance
of kinks for either samples. However, the steepness of these curves at especially low
temperature did decrease. Generally, it was concluded that the damp heat illumination
exposure did not only affect the series resistance, but also led to a changes in the
electrical transport.
224
200 200
Non -degraded 150 Non -degraded
Current density (mA/cm 2 ) 100 299K Current density (mA/cm 2 ) 100 260K
Alkali-rich
Alkali-poor
150
Illumination
Illumination
50
50
0 105K 0 105K
0 500 1000 Voltage (mV) 0 500 1000 Voltage (mV)
-50 -50
200 200
165 h degraded 150 165 h degraded
Alkali-rich
Alkali-poor
Current density (mA/cm 2 ) 100 301K Current density (mA/cm 2 ) 100 264K
150
Illumination
Illumination
50
50
107K
106K
0
0 500 1000 Voltage (mV) 0 0 500 1000 Voltage (mV)
-50 -50
Figure 7.8
Current-voltage curves at different temperatures between 100 and 300/260K for the non-degraded CIGS solar cells and solar
cells degraded for 165 hours with barrier (purple) and without barrier (blue) taken under illumination.
seem to prevent the formation of decent solar cell, as is shown in among others Table
7.1. The occurrence of a kink was not observed in the IV(T) spectra of the alkali-poor
sample under illumination. Both samples did also not show a kink in darkness.
After 165 hours of degradation, the kink could still be found for the alkali-rich sample
under illumination. For this specific sample, the impact of degradation seemed
reasonably small, which is surprising since in-situ IV measurements indicated that
o
almost half of the efficiency at 107 C has disappeared. However, at lower temperatures,
the relative loss of efficiency might have been smaller. It can be expected that other
samples, which are more degraded, show more modifications in the curves.
After degradation, the alkali-poor sample did also demonstrate the appearance of a
kink in the illuminated IV curves starting for temperatures as high as ~250K. This was
surprising, since this sample did not show large changes in their electrical parameters
due to damp heat illumination exposure. This kink is still present after 365 hours
degradation (not depicted). The IV(T) of samples degraded for more than 365 hours
were not measured.
In darkness, the exposure to damp heat and illumination did not lead to the appearance
of kinks for either samples. However, the steepness of these curves at especially low
temperature did decrease. Generally, it was concluded that the damp heat illumination
exposure did not only affect the series resistance, but also led to a changes in the
electrical transport.
224
