Environmental Engineering Reference
In-Depth Information
the establishment of reproducibility and consistency, increasing
the device parameters further. The new science emanating from
electrodeposition research, materials, and device understanding
could also help the development of various electronic devices using
other growth techniques [24].
Electrodeposited materials can be used to fabricate multi-
layer graded bandgap solar cell structures due to the capability
of changing conduction type and ability to engineer the energy
bandgap simultaneously. The use of the latest knowledge in the
electrodepositionofCuInGaSe
2
enableslow-costfabricationofthese
next-generation solar cells, as shown in Fig. 3.9. This is an n-i-p
devicestructure grownusingCuInGaSe
2
layersonglass/FTO/n-CdS
surfaces. The n-i-p structure was grown using one electrolyte by
applying voltages at 1.10 V, 0.75 V, and 0.60 V in that order (see
Fig. 3.6) for predetermined time periods. In order to deposit equal
thicknesses for three layers, the charge flow (
Q
=
It
) through the
electrolyte can be set to a constant. This process simultaneously
provides both electrical conduction type and the bandgap variation
required for these multi-layer solar cell structures. By a simple
computer programme, the number of layers can be increased to a
large number to smooth out the edge of the energy bands.
Figure 3.9
An energy band diagram of an n-i-p structure grown using
CuInGaSe
2
on a glass/FTO/n-CdS surface to form an n-n-i-p device
structure.
