Page 117 - Mirjam-Theelen-Degradation-of-CIGS-solar-cells

Temperature dependency of the electrical parameters of CIGS solar cells

SLG Au -1.8 SLG Au
Temperature coefficient (%/ o C) -0.06 SLG In Temperature coefficient (mV/ o C) -2.0 SLG In
PI
PI
-0.04

-2.2

-0.08 -2.4
10 15 500 550 600 650
Efficiency (%) Open circuit voltage (mV)
SLG Au 0.0
Temperature coefficient (mA/cm 2 / o C) 0.05 SLG In Temperature coefficient (%/ o C) -0.1 SLG Au
0.10
PI

0.00
-0.2

-0.05
20 25 30 35 40 -0.3 40 50 60 70 PI SLG In 80
Short circuit current density (mA/cm ) 2 Fill factor (%)
Figure 4.4:
Temperature coefficients of the efficiency, open circuit voltage, short circuit current density and fill factor as a function of
these parameters at room temperature.

content slightly influenced the temperature dependency of the V . However, no linear
oc
relation between the V coefficient and the sodium content could be observed, since
oc
the lowest decrease number was observed for SLG samples with an average sodium
content.

4.3.1 Normalised degradation coefficients
In order to compare the values with other types of solar cells, the temperature
coefficients need to be normalised. A different open circuit voltage or short circuit
current density at room temperature, which vary greatly between the different
PV technologies, does in this approach not directly affect the number in the table.
The following formula was followed in order to extract normalised temperature
dependency from Table 4.2 or literature:

1
a (norm) = dX x X 25 C x100 (4.4)
dT

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