Nanotechnology: Making Efficient Solar Cells for Clean Energy

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Speaker: Prof. Devki N. Talwar
Professor & Chair, Department of Physics , Indiana University of
Pennsylvania, Indiana


Abstract of the Talk:

The biggest cause of global warming on earth is the release of
carbon dioxide when fossil fuels such as oil, natural gas and coal are
burned to produce energy. The main function of carbon dioxide present in
the atmosphere is to trap heat obtained from sunlight and do not let it go
beyond the atmosphere. When there is a rise in the percentage of carbon
dioxide in air, the amount of heat captured by carbon dioxide
also increases contributing towards overall rise in the surface
temperature of the earth or global warming. Solar energy i.e., power from
the sun is a vast and inexhaustible resource. Given the abundance of solar
energy, this resource is poised to play a prominent role in our
energy needs. If highly efficient solar cell is designed produced and
put in place to convert “solar energy” into useful energy - the fossil
fuel will be freed up and never cause turmoil in the World
economy. Clearly, solar-energy represents a clean alternative to
the fossil fuels which are polluting our air, water, threaten our
public health, and contribute to global warming. The conventional solar
cells made by amorphous silicon (a-Si) are by far the least expensive but
result in low efficiency. Number of expensive materials such as
gallium arsenide (GaAs), copper-indium-diselenide (CuInSe2),
cadmium-telluride (CdTe) and gallium indium nitrides (GaInN) are used
to make solar cells with higher efficiencies. These new materials exhibit
interesting properties, including the ability to manufacture solar
cells which are sensitive to different parts of the light
spectrum. Recent progress in nanotechnology has however opened the
door to the production of much cheaper (plastic-based) and more
efficient solar cells. The purpose of this talk is to present
an overview of solar cells, in general, and the novel solar-cells, in
particular, which utilize tiny nano-particles (quantum dots and nanorods)
dispersed within a polymer. These nano-particles when absorb light of a
specific wavelength they generate electrons. These electrons flow
through the nano-particles until they reach the aluminum electrode
where they are combined to produce a current. This type of cell is
cheaper to manufacture than the conventional ones for two main reasons:
(i) the plastic cells are not made from silicon (ii) manufacturing of
these cells does not require expensive equipment such as clean
rooms or vacuum chambers like conventional silicon based solar cells.

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