Page 23 - Mirjam-Theelen-Degradation-of-CIGS-solar-cells
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Introduction
In chapter 5, the behaviour of molybdenum films exposed to damp heat conditions
is extensively described. In order to learn more about their damp heat stability and its
relationship with the deposition conditions, molybdenum films were deposited at dif -
ferent pressures, which led to changes in their morphology: Films deposited at lower
deposition pressures resulted in more dense films. Furthermore, some films were de-
graded ‘as-deposited’ (without any post-processing), while other films were selenised
before degradation in order to form a thin layer of MoSe .
2
In chapter 6, the impact of various degrading conditions on aluminium doped zinc
oxide films (ZnO:Al) is presented. Both variations in deposition conditions (room
o
temperature versus 200 C) and in degradation conditions (damp heat versus water
purged with either N , O or CO ) are described. Here it is shown that damp heat expo -
2
2
2
sure leads to increased resistivity of these transparent conductors.
Chapter 7 and chapter 8 discuss the degradation of complete CIGS solar cells. Chapter
7 demonstrates the degradation of CIGS solar cells with different quantities of sodium
and potassium (alkali-elements) when degraded in the hybrid degradation setup. The
impact of damp heat and illumination exposure on these solar cells on both the elec-
trical and the compositional properties is presented.
Chapter 8 describes the impact of atmospheric species on complete CIGS solar cells.
Analogue to chapter 6, it demonstrates that exposure of these solar cells to water and
large quantities of CO led to rapid loss of efficiency. This was caused by partial disso-
2
lution of the ZnO:Al, likely in the regions near the grain boundaries, which resulted in
a large decrease in the short circuit current and an increase in the series resistance.
The last two chapters present the overview, outlook and summaries. Chapter 9 dis-
cusses an overview of the degradation mechanisms and their impact on the electrical
parameters of CIGS solar cells. This information is both obtained from the studies in
this thesis and from the literature. Additionally, recommendations for further studies
on CIGS solar cell and module reliability are given. Chapter 10 provides summaries for
this thesis in English, Dutch and French.
Appendices A and B show an overview of the used analysis techniques and the used
abbreviations, respectively. The thesis ends with the 'dankwoord / acknowledge-
ments', an overview of publications, presentations and awards and the curriculum
vitae of Mirjam Theelen.
21
In chapter 5, the behaviour of molybdenum films exposed to damp heat conditions
is extensively described. In order to learn more about their damp heat stability and its
relationship with the deposition conditions, molybdenum films were deposited at dif -
ferent pressures, which led to changes in their morphology: Films deposited at lower
deposition pressures resulted in more dense films. Furthermore, some films were de-
graded ‘as-deposited’ (without any post-processing), while other films were selenised
before degradation in order to form a thin layer of MoSe .
2
In chapter 6, the impact of various degrading conditions on aluminium doped zinc
oxide films (ZnO:Al) is presented. Both variations in deposition conditions (room
o
temperature versus 200 C) and in degradation conditions (damp heat versus water
purged with either N , O or CO ) are described. Here it is shown that damp heat expo -
2
2
2
sure leads to increased resistivity of these transparent conductors.
Chapter 7 and chapter 8 discuss the degradation of complete CIGS solar cells. Chapter
7 demonstrates the degradation of CIGS solar cells with different quantities of sodium
and potassium (alkali-elements) when degraded in the hybrid degradation setup. The
impact of damp heat and illumination exposure on these solar cells on both the elec-
trical and the compositional properties is presented.
Chapter 8 describes the impact of atmospheric species on complete CIGS solar cells.
Analogue to chapter 6, it demonstrates that exposure of these solar cells to water and
large quantities of CO led to rapid loss of efficiency. This was caused by partial disso-
2
lution of the ZnO:Al, likely in the regions near the grain boundaries, which resulted in
a large decrease in the short circuit current and an increase in the series resistance.
The last two chapters present the overview, outlook and summaries. Chapter 9 dis-
cusses an overview of the degradation mechanisms and their impact on the electrical
parameters of CIGS solar cells. This information is both obtained from the studies in
this thesis and from the literature. Additionally, recommendations for further studies
on CIGS solar cell and module reliability are given. Chapter 10 provides summaries for
this thesis in English, Dutch and French.
Appendices A and B show an overview of the used analysis techniques and the used
abbreviations, respectively. The thesis ends with the 'dankwoord / acknowledge-
ments', an overview of publications, presentations and awards and the curriculum
vitae of Mirjam Theelen.
21
