Civil Engineering Reference
In-Depth Information
expected that electronics, optics and material science amongst others would
also be considered.
Currently, two main areas where nanotubes are being used which have
been published are:
NASA's decision to develop a composite material from NT and another
material to be used in spacecraft.
The delivery of medical drugs by attaching the drugs to the
nanotubes.
Although these two examples are not in the photovoltaic fi eld, they
demonstrate how broad the use of nanotubes could be. However, this
chapter is specifi cally interested in their relationship to support and enhance
the development of the third generation PV and its continuous aim to
develop a panel that uses materials that have a higher conversion effi ciency
rate.
Nanotubes are widely believed to be one of the forerunners in third
generation PVs and it is expected that in the next decade their effi ciency
and cost will improve signifi cantly (Anon., 2010). If this development
happens, it will be due to several advancements that are linked together to
provide the ideal material for photovoltaic panels. In the future, with these
improvements it is expected that panels will not only withstand extended
sunlight but also be able to be bent into any form due to their physical
characteristics. They also accept high currents but withstand the effect of
the heat generated. A very important point for any material being introdu-
ced into a system is that there should be no reaction with its surroundings
and the NT complies with this. Finally, but importantly, it must provide good
conduction without loss of energy to friction.
One of the most important environmental aspects is that the NT is both
easy to reuse (Scharber, n.d.) and is biodegradable, hence it can be decom-
posed, answering one often-posed question about how to deal with the
end-of-life cycle of renewable energy products. However, more pressing
issues are related to problems and obstacles that need to be overcome to
ensure that NT PV have a chance of succeeding in this industry. The issue
of cost effectiveness needs to be addressed, as does the improvement of
mass production to ensure quality products. In addition, the high tempera-
ture needed to produce the nanotubes could affect other components used
in the solar cell/panel, hence this needs to be considered. One technical
issue that needs more research is the problem with low fi ll factor which is
only adding to the low energy conversion effi ciency problem.
Carbon nanotubes are currently used in several areas of the PV device.
One such area is the photoactive layers, which are expected to provide more
effi cient PV devices due to the nanotube and polymer junctions. The high
electric fi eld created here enables splitting up of the excitons and also in
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