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Chapter 1
degradation properties of the CIGS solar cells under humidity, illumination
and temperature. Additionally, an ‘atmospheric species’ test was developed, in
order to learn more about the impact of atmospheric species.
1.6 Outline of the thesis
In this chapter, a short introduction about photovoltaics in general and more in-depth
on CIGS solar cells and modules and their individual layer is given. Additionally, the
reason for reliability research on these materials is introduced. Finally, the scope, re-
search objectives and structure are presented.
In chapter 2, a detailed literature overview on the degradation behaviour of CIGS
solar cells and their individual layers is given. In this chapter, results from this thesis
have also been included to yield a complete overview. The hybrid degradation set-up
allowing in-situ monitoring of the degradation properties is described in chapter 3.
Additionally, the theory behind current-voltage measurements and the data interpre -
tation as is used in this thesis are introduced. The special design for CIGS solar cells as
used in this thesis is also described.
The temperature dependency of the electrical parameters of CIGS solar cells on poly-
imide and soda lime glass is shown in chapter 4. In this chapter, it is shown that the
output of CIGS solar cells strongly depends on their temperature, while this impact
differs for different types of CIGS solar cells. This knowledge is relevant for CIGS mod-
ules in the field, but is also very important for the interpretation of lifetime results
as described in this thesis, since many experiments have been executed at elevated
o
o
temperatures (like 85C or 107C). In this chapter, it is shown that the studied CIGS
solar cells have temperature dependencies of their efficiency varying from -0.36 to
o
-0.70 relative %/ C. It is also described that the temperature dependency of the short
circuit current can be either positive and negative and likely depends largely on the
recombination in the solar cells. It is also shown that solar cells with a higher open
circuit voltage actually have a lower temperature dependency.
Chapters 5, 6, 7 and 8 present the actual behaviour of CIGS solar cells and individual
layers under the various degradation conditions. These chapters also include recom-
mendations which deposition conditions lead to the most stable solar cells, prefera-
bly without the loss of initial properties.
20
degradation properties of the CIGS solar cells under humidity, illumination
and temperature. Additionally, an ‘atmospheric species’ test was developed, in
order to learn more about the impact of atmospheric species.
1.6 Outline of the thesis
In this chapter, a short introduction about photovoltaics in general and more in-depth
on CIGS solar cells and modules and their individual layer is given. Additionally, the
reason for reliability research on these materials is introduced. Finally, the scope, re-
search objectives and structure are presented.
In chapter 2, a detailed literature overview on the degradation behaviour of CIGS
solar cells and their individual layers is given. In this chapter, results from this thesis
have also been included to yield a complete overview. The hybrid degradation set-up
allowing in-situ monitoring of the degradation properties is described in chapter 3.
Additionally, the theory behind current-voltage measurements and the data interpre -
tation as is used in this thesis are introduced. The special design for CIGS solar cells as
used in this thesis is also described.
The temperature dependency of the electrical parameters of CIGS solar cells on poly-
imide and soda lime glass is shown in chapter 4. In this chapter, it is shown that the
output of CIGS solar cells strongly depends on their temperature, while this impact
differs for different types of CIGS solar cells. This knowledge is relevant for CIGS mod-
ules in the field, but is also very important for the interpretation of lifetime results
as described in this thesis, since many experiments have been executed at elevated
o
o
temperatures (like 85C or 107C). In this chapter, it is shown that the studied CIGS
solar cells have temperature dependencies of their efficiency varying from -0.36 to
o
-0.70 relative %/ C. It is also described that the temperature dependency of the short
circuit current can be either positive and negative and likely depends largely on the
recombination in the solar cells. It is also shown that solar cells with a higher open
circuit voltage actually have a lower temperature dependency.
Chapters 5, 6, 7 and 8 present the actual behaviour of CIGS solar cells and individual
layers under the various degradation conditions. These chapters also include recom-
mendations which deposition conditions lead to the most stable solar cells, prefera-
bly without the loss of initial properties.
20
