Environmental Engineering Reference
In-Depth Information
growth technique, otherwise called the electrodeposition (ED)
technique. For PV development, the technology used should be low-
cost, scalable and manufacturable in order to produce low-cost
solarpanelsforterrestrialenergyconversion.Theelectrodeposition
satisfies all three criteria mentioned above, and hence it is worth
exploring and developing this technique for the production of solar
energy materials and solar cells.
The electrodeposition of single elements, especially metals,
is a well-established subject and has been used for centuries
in the extraction of metals from their natural ores and in the
coating of jewellery with noble metals, such as gold and silver.
However,theuseofelectrodeposition forgrowthofsemiconducting
materials was first introduced after the late 1970s [1-5]. The
work on the electrodeposition of II-VI semiconductors in the early
1980s led to the fabrication of CdS/CdTe solar cells based on
electrodeposited CdTe layers [6]. In the early 1980s, the production
of a thin-film solar cell with lab-scale device e
ciency greater
than 8% was a remarkable achievement and has during the
past three decades stimulated worldwide research interest in the
electrodeposition of semiconductors. The work has spread into
many other materials, such as III-V, I-III-VI
2
, organic polymers,
and other alloy semiconductors. There have also been attempts to
grow elemental semiconductors such as silicon [7] and mechani-
cally harder materials like nitrides [8]. This chapter reviews the
strengths,advantagesanddisadvantagesofthissimplebutpowerful
techniqueinthedevelopmentofmacroelectronicdevicessuchasPV
solar panels and large-area display devices [9].
3.2 Electrodeposition of Semiconductors
The electrodeposition of semiconductors requires an electrolyte
containing appropriate ions and three electrodes, as shown in
Fig. 3.1 [10], or a simple two-electrode system eliminating the
reference electrode. Consider CuInGaSe
2
, a commonly used solar
cell material, as an example. This material growth process needs an
aqueoussolutioncontainingpositiveionsofcopper,indium,gallium
and selenium. Once a small DC power, typically in the mW range
