Laura Kraft
Wilson Pfeiffer
Solar Energy and Solar Cells
Introduction
A. General Purpose/Uses of Solar Energy
Across the world, one big topic among many nations is renewable energy, and more specifically solar energy. Why is that? What exactly is the purpose of this renewable energy, what is everyone raging about, and why should our world make efforts to begin harnessing the power that our sun can provide? Solar energy is effectively taking the energy from the sun and converting it into usable energy. “Being continually replenished by nature, solar energy is an energy source that cannot be depleted. Assuming 100% absorption of solar radiation, it would only require 88 minutes of solar radiation to cover for humanity’s total energy consumption for a year.” 4 Our sun provides an immense amount of potential energy to our world, but it needs to be harnessed and transformed to be used. The five major modes for the transformation are illustrated in Scheme 1.
Scheme 1.
Five Major Modes for the Application of Solar Power
The way most of the energy is currently created across the world is through the burning of fossil fuels. While this is a common method of creating energy, it poses many problems. Efficiency of a coal powered thermal power plant is roughly 30-40%, and it is difficult to explain the
1

Laura Kraft
Wilson Pfeiffer relationship between total solar energy supplied (kWh), and avoided emissions (kg of CO
2
).
1 As stated, the major problem with burning coal and other fossil fuels is that CO
2
gas is produced, which is damaging our environment when released.
1 SO
2
, NO x
, CO
2
, and other emissions cause environmental issues as they reach higher levels.
2 On the other hand, solar energy is arguably the cleanest and most abundant source of energy.
2 While the burning of fossil fuels is damaging, solar energy is nearly harmless. Non-biomass renewable energy resources do not emit greenhouse gases directly into our atmosphere.
3 Additionally, unlike other methods of creating energy, it doesn’t bear the fear of losing resources. As biomass materials such as oil, coal, wood, etc. start to run out, the prices will continue to sky-rocket and resources will deplete. Recently, the production and use of renewable fuels has grown due to higher oil and natural gas prices; another reason to continue to push towards the use of solar power.
3 The potential of solar power as well as other renewable resources could eventually rid of the use of fossil fuels.
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Scheme 2 . Four Main Types of Solar Cells
Structure of CuInGaSe_2 Solar Cell Dye-Sensitized Solar Cell
Sensitized Inorganic Solar Cell
B. General Types of Solar Cells
2
Polymer Solar Cell

Laura Kraft
Wilson Pfeiffer
Solar cells turn sunlight directly into electricity. There are many different types of solar cells and much research id dedicated to increase the efficiencies of all types of solar cells. Solar cells became somewhat familiar in the 1960's and 1970's as they were used to provide electrical power to space vehicles.
5 Solar cells are photovoltaic cells and they employ semiconductor materials and there are four main types of solar cells (Scheme 2).
For example, one of these four types of solar cell is a dye-sensitized solar cell. These cells use a semiconductor, an electrolyte, and a dye to convert the sun’s rays into chemically induced energy. One example could use titanium oxide as a semiconductor, and a dye such as
C102 to perform the reaction. Another example of a solar cell is a polymer solar cell (Scheme
3).
Scheme 3 . Dye C102 and Polymers P3HT-OH and P3HT
Polymer solar cells can be made with a thin film of polymer between two metallic conductors such as indium tin oxide and aluminum.
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Electrons flow from one conductor (the one with the highest energy electrons) to another conductor (the one with the lowest energy electrons) until they reach the same chemical potential. This process creates a charge and generates an electric field across the semiconductor. The electric field pulls electrons to the positive electrode leaving space in the negative electrode when the semiconductor absorbs light. The current and voltage that results could be used to do work or charge a battery.
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One application of polymer solar cells is the plastic solar cell. These cells can be put to use in a confined space such as an apartment window in the city. These plastic solar cells are much smaller and can be used virtually anywhere. The mechanical flexibility of plastic materials can be easily used for all photovoltaic applications onto curved surfaces in any architectural setting.
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These solar cells effectively take the same process of other polymer solar cells on a micro scale, but they allow use in confined
3

Laura Kraft
Wilson Pfeiffer areas. By casting thin films of semi-transparent plastic PV between insulating window glass, large unused areas, such as windows, can be used to generate power.
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C. Statement of Need and Outline of Approach
Materials & Methods
Results
Discussion
Conclusion
References
(1) Pinto, G. Determining the CO2 Emissions Averted by the Use of Solar Power. J. Chem.
Educ . 2009 , 86 , 1033.
(2) Edinger, V, Kentel, E. Renewable energy potential as an alternative to fossil fuels in
Turkey. Energy Conversion and Management 1999 , 40 , 743-755.
(3) Renewable Energy Sources. U.S. Energy Information Administration. Online at <http:// www.eia.gov/> Accessed 2/1/13.
(4) Green, D. Renewable green energy power. 2011 , 1-3. Online at http://www. renewablegreenenergypower.com/ Accessed 2/1/13.
(5) Mickey, C. Solar Photovoltaic Cells. Chem. Principals Revisited 1982 , 58 , 418-423.
(6) McGehee, M., Topinka, M. Solar Cells Pictures from the Blended Zone. Nature 2006 , 5 ,
675-676.
(7) Brabec, C., Hummelen, J., Sariciftci, N. Plastic Solar cells. Advanced Functional Material
2001 , 11 , 15-2.
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