Analysis of Silicon-Perovskite Tandem Solar Cells for Solar Energy

This report examines the potential of silicon-perovskite tandem solar cells to increase the efficiency and reduce the cost of solar energy. It begins by discussing the limitations of current silicon-based solar cells, including the theoretical efficiency limits and the tradeoffs associated with bandgap selection. The report then introduces metal-halide perovskite as a promising material for tandem solar cells due to its lower manufacturing costs and high voltage output. The analysis compares the performance of silicon and metal-halide perovskite, highlighting the advantages of the latter in terms of energy conservation. The core of the report focuses on the design of silicon-perovskite tandem solar cells, explaining how the use of two absorbers—one for ultraviolet and visible light and another for infrared light—minimizes energy losses. The design incorporates a tunnel junction and a transparent electrode to connect the layers and extract power. The report concludes with a brief overview of metal-halide perovskite, describing its crystalline structure and composition.

Running head: SOLAR ENERGY
SOLAR ENERGY
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MAKING SOLAR ENERGY AFFORDABLE
Most of the contemporary solar photovoltaic cells are made using silicon, which has an
efficiency of about 25.6%. The theoretical limit of the efficiency obtainable when only one light
absorbing material is used in the manufacture of the solar cells is 34%. The theoretical limit
tends to increase and becomes about 46% when more than one light absorbing material is used.
The use of tandem solar cells from two light-absorbing materials can then be such a good
strategy in increasing the efficiency of photovoltaic solar cells (Kennedy, 2012). This will ensure
increased efficiency at the same time maintaining low cost during manufacturing.
The tandem solar cells in this analysis make use of silicon and metal-halide perovskite in the
manufacture of the solar cells. Metal-halide perovskite is a material that has the ability to be
manufactured at lower costs (Towler, 2014). This idea and analysis provides a platform for
silicon-perovskite tandem solar cells and provides an avenue for the manufacture of low cost and
high-efficiency solar cells.

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It is important to observe the reaction of various solar cells materials to incoming light in order
to gain a better understanding of why tandem solar cells have the ability to enhance efficiency.
Sunlight has a range of energies from ultraviolet light through visible light and infrared light.
Ultraviolet light and visible light have higher levels of energy that infrared light. A solar cell
makes use of semiconducting material to absorb the light from the sun and change it into
electrical power. The semiconductor has a special feature called bandgap that enables it to absorb
light as well as extra energy from the absorbed light in the form of electricity. A tradeoff exists
when the bandgap of absorbing material is being chosen. A smaller bandgap results into a wider
energy range being absorbed from the sun thereby more current is being generated
(Paranthaman, 2015). However, a smaller bandgap translates to a lower voltage of extracting the
electrical current and since power is a product of voltage and the current, it means there will be
low power production.
A contemporary silicon solar cell produces 0.5 V
12-volt solar panel produces 12*0.5= 17 V at peak
Using a current of 3.5 A for the panel, the wattage can be estimated
Power=Voltage * Current=17*3.5
=59.6 W
A metal-halide perovskite, on the other hand, produced a voltage of 1.5V per cell
Assuming a 12 voltage panel as the case with the silicon solar cell
Total voltage=1.5*12=50V at peak

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Current=3.5 A
Power of the solar panel=3.5*51
=178.5 W
Efficiency of the metal-halide perovskite= (178.5-50)/50*100
=257% efficient
This means that metal-halide perovskite conserves energy more than twice as much as the
contemporary silicon solar cells. Metal-halide perovskite produces very high voltages as a result
of the elimination of tradeoff as discussed below
Tandems are important in reducing this tradeoff. When two absorbers are used, each of the
absorbers will specialize in one portion of the solar spectrum as opposed to the case of a single
absorber that will have to cover the whole spectrum (Towler, 2014). While the first absorber will
be specializing in the ultraviolet and visible photons, the second absorber that will be lying just
beneath the first one will specialize on the infrared photons. The use of these specialized
absorbers greatly minimizes losses of energy when sunlight is lost in the form of heat rather than
electric current.
In this analysis, the metal-halide perovskite is used as the first absorber in trapping ultraviolet
and visible light while silicon serves as the second absorber, capturing infrared light. The design
develops two layers that are unique to a tandem solar cell and are not used in the contemporary
solar cells. An electrically connecting layer known as a tunnel junction was made using silicon
and was used to connect the two light absorbing materials. A transparent electrode was also
made. The electrode conducts electricity at the same time allowing light to pass through it. The

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purpose of the transparent electrode was to connect the solar cell to the external wires to allow
extraction of power (Hardyman, 2013). The transparent electrode was made from a mesh of
silver nanowires, which resembles a chain link fence made of wires, which are thousands of
times thinner than the diameter of the human hair. Using such layers, it is possible to start
designing the other layers in solar cells with multiple layers.
Metal-halide perovskite
Metal-halide perovskite is increasingly becoming one of the most popular materials for
photovoltaic cells. The term “perovskite” is used to define a crystalline structure of a material
that is composed of three components in a ratio of 1:1:3. The metal-halide perovskite that is used
in the making photovoltaic is three parts halide, one part metal, and one part an organic
molecule. A semiconductor is formed when iodine, lead and methyl ammonium, which are the
three parts of metal-halide perovskite used in photovoltaic, is combined.

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References
Hardyman, R. (2013). How a Solar-Powered Home Works. New York: The Rosen Publishing
Group.
Kennedy, D. (2012). Rooftop Revolution: How Solar Power Can Save Our Economy-and Our
Planet-from Dirty Energy. London: Berrett-Koehler Publishers.
Paranthaman, M. P. (2015). Semiconductor Materials for Solar Photovoltaic Cells. Oxford:
Springer.
Towler, B. F. (2014). The Future of Energy. London: Elsevier Science.