Page 21 - Mirjam-Theelen-Degradation-of-CIGS-solar-cells
P. 21
Introduction
costs as well as accelerate the introduction of flexible CIGS modules to the market.
Knowledge about intrinsically more stable CIGS solar cells might thus also help CIGS
module producers that are currently producing stable, but relatively expensive mod-
ules. An overview of the reduction of electricity cost due the improvement of the sta-
bility and predictability of CIGS solar cells is shown in Figure 1.10.
1.5 Aim and scope of this thesis
Within this thesis, we aimed to obtain better understanding about the long term sta-
bility of CIGS solar cells and modules. This knowledge was then used to optimise CIGS
solar cells and modules concerning their stability. For this, several research questions
have been addressed in this thesis:
1. What is the influence of humidity, temperature, illumination and various
atmospheric species on the stability of CIGS solar cells?
2. Which layers or interfaces in CIGS solar cells are the most critical materials
during exposure to these conditions?
3. Which electrical parameters of CIGS solar cells are most influences by exposure
to these conditions?
4. Which chemical reactions are associated with the changes in electrical
parameters?
5. How can we modify the deposition conditions or composition of the CIGS solar
cells to prevent these chemical reactions?
In order to answer these questions, the following scope has been determined for this
thesis:
1. The exposure of CIGS solar cells to various accelerated lifetime tests, in which
temperature, humidity, illumination and atmospheric species are used as a load.
In order to obtain better understanding, the changes in electrical parameters
and the associated occurring chemical reactions, have been determined.
2. Since the complete CIGS solar cell is a very complicated system, various
individual layers, including molybdenum and ZnO:Al films have also been
exposed to various loads. For these layers, the changes in electrical parameters
and chemical reactions were also identified. The knowledge obtained in these
experiments has helped the identification of the changes occurred in complete
CIGS solar cells.
3. Since the required test methods for points 1) and 2) did not all exist, new testing
methods for solar cells and its individual layers have been developed: a hybrid
degradation set-up was designed and built in order to in-situ monitor the de
19
costs as well as accelerate the introduction of flexible CIGS modules to the market.
Knowledge about intrinsically more stable CIGS solar cells might thus also help CIGS
module producers that are currently producing stable, but relatively expensive mod-
ules. An overview of the reduction of electricity cost due the improvement of the sta-
bility and predictability of CIGS solar cells is shown in Figure 1.10.
1.5 Aim and scope of this thesis
Within this thesis, we aimed to obtain better understanding about the long term sta-
bility of CIGS solar cells and modules. This knowledge was then used to optimise CIGS
solar cells and modules concerning their stability. For this, several research questions
have been addressed in this thesis:
1. What is the influence of humidity, temperature, illumination and various
atmospheric species on the stability of CIGS solar cells?
2. Which layers or interfaces in CIGS solar cells are the most critical materials
during exposure to these conditions?
3. Which electrical parameters of CIGS solar cells are most influences by exposure
to these conditions?
4. Which chemical reactions are associated with the changes in electrical
parameters?
5. How can we modify the deposition conditions or composition of the CIGS solar
cells to prevent these chemical reactions?
In order to answer these questions, the following scope has been determined for this
thesis:
1. The exposure of CIGS solar cells to various accelerated lifetime tests, in which
temperature, humidity, illumination and atmospheric species are used as a load.
In order to obtain better understanding, the changes in electrical parameters
and the associated occurring chemical reactions, have been determined.
2. Since the complete CIGS solar cell is a very complicated system, various
individual layers, including molybdenum and ZnO:Al films have also been
exposed to various loads. For these layers, the changes in electrical parameters
and chemical reactions were also identified. The knowledge obtained in these
experiments has helped the identification of the changes occurred in complete
CIGS solar cells.
3. Since the required test methods for points 1) and 2) did not all exist, new testing
methods for solar cells and its individual layers have been developed: a hybrid
degradation set-up was designed and built in order to in-situ monitor the de
19
