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Experimental information
3.2 CIGS solar cell preparation
Most samples used in the experiments have a relatively standard CIGS stack as
described in chapter 1.3 and shown in Figure 3.2a. This stack consists of Soda Lime
Glass (SLG)/molybdenum (Mo)/CIGS/cadmium sulfide (CdS)/intrinsic zinc oxide
(i-ZnO)/aluminium doped zinc oxide (ZnO:Al). The general deposition conditions are
as described by Couzinie-Devy with the exception of the ZnO:Al layer thickness, which
has been increased to 1 μm [1]. This results in ZnO:Al layer with a sheet resistance
under 10 Ω/☐ which is required for the use of relatively long cells (5 mm) without grids.
These choices were made in order to optimally simulate the cells in CIGS modules,
while the relatively large cell size was also chosen to prevent the dominance of the
edge degradation on the output of the complete sample. These design choices result
in an initial efficiency loss of approximately 2% points compared to reference samples
with a standard cell design based on thin ZnO:Al combined with grids. In order to
prevent shadowing, the contacts of the samples are not above the actual cell, but on
either sides of the active area (Figure 3.2b). The back and front contacts were covered
with evapourated gold, which is stable under damp heat. Figure 3.2c and Figure 3.2d
depict the sample holders with a solar cell as used in the experiments described in this
thesis and the new designed sample holder respectively.
3.3 The hybrid degradation setup
The hybrid degradation setup (Figure 3.1) consists of a climate chamber for humidity
and temperature control with a large window in the side wall. Outside of the window,
a steady-state solar simulator is placed allowing the light to enter the climate chamber
in a controlled manner. All relevant parameters are logged and controlled by a
measurement system, that can also supply external loads. More information about
the setup can be found in Video 3.1, which shows the climate chamber, solar simulator,
sample holders and the measurement system. For the thesis on paper, this movie can
be found on https://www.youtube.com/watch?v=Zmy5tb-2NK8.
Video 3.1: The hybrid degradation setup
For temperature and humidity control, a modified Espec Temperature Chamber
model ARL-1100 was utilised (Hielkema Testequipment, Uden, the Netherlands).
The right side of the chamber was removed and replaced by a window system.
This window system consists of two high transmission glass slides combined with a
polymer slide covered with Eternal Sun optical foil. This combination was chosen to
obtain an optimal combination of thermal isolation and spectral filtering of the light.
A shutter was installed on the climate chamber, so the samples can also be exposed
95
3.2 CIGS solar cell preparation
Most samples used in the experiments have a relatively standard CIGS stack as
described in chapter 1.3 and shown in Figure 3.2a. This stack consists of Soda Lime
Glass (SLG)/molybdenum (Mo)/CIGS/cadmium sulfide (CdS)/intrinsic zinc oxide
(i-ZnO)/aluminium doped zinc oxide (ZnO:Al). The general deposition conditions are
as described by Couzinie-Devy with the exception of the ZnO:Al layer thickness, which
has been increased to 1 μm [1]. This results in ZnO:Al layer with a sheet resistance
under 10 Ω/☐ which is required for the use of relatively long cells (5 mm) without grids.
These choices were made in order to optimally simulate the cells in CIGS modules,
while the relatively large cell size was also chosen to prevent the dominance of the
edge degradation on the output of the complete sample. These design choices result
in an initial efficiency loss of approximately 2% points compared to reference samples
with a standard cell design based on thin ZnO:Al combined with grids. In order to
prevent shadowing, the contacts of the samples are not above the actual cell, but on
either sides of the active area (Figure 3.2b). The back and front contacts were covered
with evapourated gold, which is stable under damp heat. Figure 3.2c and Figure 3.2d
depict the sample holders with a solar cell as used in the experiments described in this
thesis and the new designed sample holder respectively.
3.3 The hybrid degradation setup
The hybrid degradation setup (Figure 3.1) consists of a climate chamber for humidity
and temperature control with a large window in the side wall. Outside of the window,
a steady-state solar simulator is placed allowing the light to enter the climate chamber
in a controlled manner. All relevant parameters are logged and controlled by a
measurement system, that can also supply external loads. More information about
the setup can be found in Video 3.1, which shows the climate chamber, solar simulator,
sample holders and the measurement system. For the thesis on paper, this movie can
be found on https://www.youtube.com/watch?v=Zmy5tb-2NK8.
Video 3.1: The hybrid degradation setup
For temperature and humidity control, a modified Espec Temperature Chamber
model ARL-1100 was utilised (Hielkema Testequipment, Uden, the Netherlands).
The right side of the chamber was removed and replaced by a window system.
This window system consists of two high transmission glass slides combined with a
polymer slide covered with Eternal Sun optical foil. This combination was chosen to
obtain an optimal combination of thermal isolation and spectral filtering of the light.
A shutter was installed on the climate chamber, so the samples can also be exposed
95
