MATERIALS DEVELOPMENT FOR
SOLAR ENERGY APPLICATION
By
Dr. S.O.O. Olusunle, R.Eng., MASME, FMSN
Ag Director/Chief Executive, Engineering Materials Development Institute, Akure
at a Public Lecture organized by
The Metallurgical, Mining and Materials Division of the Nigerian Society of Engineers
21/02/2011
OUTLINE
 Background
 Introduction
 Solar
Energy
 Harvesting Solar Energy
 EMDI Effort on Solar Energy Development
 Available Facilities @ EMDI
 Conclusion
Background
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About 80% of Africa’s 1 billion population is engulfed in abject
poverty and is lacking virtually in all areas of human
development
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Access to energy plays a central role in solving the poverty
debacle
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Africa is referred to as a “dark continent” because about 70%
of the population do not have access to electric lighting.
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Over 1.6 billion people in developing countries do not have
access to electricity and have no hope of being connected to
the national grid in the near future (World Bank, 1996).
Introduction
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Fossil fuels provide around 66% of the world's
electrical power, and 95% of the world's total energy
demands.
Global warming (green house effect) and climate
changes are due to the use of these fossil fuels like
coal, oil and gas.
by-products of fossil fuels such as carbon dioxide,
sulfur and nitrogen oxide may result in acid rain
Sourcing for clean, efficient, and sustainable energy
is therefore a necessity
solar energy stands out because the source is
unlimited and available everywhere
Solar Energy
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Solar energy is the energy directly from the sun which is
one of the most important non-conventional energy
sources available for man’s use.
It is clean, renewable and free source of energy largely
available in sufficient quantity
Man can harness the energy for useful purposes by
means of active and passive devices among which are
solar cells and photothermal converters.
However, the challenges of solar power generation are its
production cost and storage. The primary objective of the
worldwide research and development is to reduce the cost
of generating solar energy to a level that will be
competitive with conventional ways of generating power.
History
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Humans have harnessed the power of the sun for millennia.
In the fifth century B.C., the Greeks took advantage of passive
solar energy by designing their homes to capture the sun’s
heat during the winter.
Later, the Romans improved on solar architecture by covering
south-facing windows with clear materials such as mica or
glass, preventing the escape of solar heat captured during the
day
In the 1760s, Horace de Saussure built an insulated
rectangular box with a glass cover that became the prototype
for solar collectors used to heat water. The first commercial
solar water heaters were sold in the U.S. in the late 1890s
In the late 19th century, inventors and entrepreneurs in
Europe and the U.S. developed solar energy technology that
would form the basis of modern designs
Production
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Sunlight can be converted into heat and electricity
in a number of ways.
 A variety of solar technologies are in production,
and many companies and researchers are
pursuing efforts to develop devices that convert the
sun’s energy more efficiently
 Energy from the sun is harvested using either
photothermal conversion system which converts
solar radiation into heat energy or solar cell which
convert radiation from the sun directly to electricity.
Materials for Harvesting Solar Energy
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Energy from the sun is harvested using either photothermal
conversion system which converts solar radiation into heat
energy or solar cell which convert radiation from the sun
directly to electricity.
The development of materials for solar energy harvesting is
based on the use of solar radiation and profound understanding
of the materials properties at the atomic scale levels.
Material structure-property relations enable the evolution of
tailored-made materials for these applications. To achieve this
objective, it requires the combination of experiments (i.e.,
materials synthesis, characterization of structural and processing
of thin film for both solar cells and photo thermal conversion),
theoretical analysis which cover modeling of the entire system.
Development of Photo thermal Converter
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Photothermal converter is device developed
using special materials that absorb solar
radiation and convert it to heat energy.
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The high efficiency photothermal material
implies maximum absorption of incident solar
radiation with a minimum thermal and optical
loss.
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The temperatures ranging from ambient to
1000°C are achievable in a photothermal
converter made of good selective materials,
such as black nickel, black chrome, multi-layer
tandem stacks and some other composite
semiconductor materials which are good
absorber (low reflection) of solar radiation and
poor emitter of thermal radiation.
The temperatures above ambient are used in
various applications such as space heating,
water heating, and distillation and drying.
Solar water heater
Solar Box cooker
Solar furnance at Odeillo, France
Max Temp 3800°C
Solar Cell Development
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A solar cell is a semiconductor device that converts sunlight directly into
electric current using the principle of photovoltaic (PV) effect.
The effect is made by partnering p-type and n-type semiconductor. The
semiconductors are selected such that they absorb significant portion of
the solar spectrum.
The absorbed photon gives rise to Electron-Hole pairs. These excess
carriers are swept across the junction by the electric field and are
collected at the contacts. This gives rise to photocurrent and can be
made to deliver power to a load.
Thus the important steps in solar energy conversion are absorption of
radiation, generation of carriers, diffusion of majority carriers, separation
of minority carriers by the electric field and collection of carriers at the
contact.
Historically, solar cells are used as an alternative source for generating
electric power, such as remote area power systems, handheld
calculators, and water pumps.
However, a major barrier impeding the development of large-scale
power application of PV systems is the high price of commercially
available solar cell modules.
Photovoltaic Energy
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Silicon based photovoltaic cells represent
90% of the photovoltaic panels presently
sold in the world.
• More than one third of the cost is due to the
silicon itself. Indeed, its purification,
crystallization and the wafer fabrication have
an important energetic and economical cost.
• The photovoltaic research community is
looking for solar cell structure based on
thinner silicon layers.
• However, the thinner the material, the lower
its light absorption, especially at long
wavelengths (near infrared).
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So the primary objective of solar cell
research and development is to reduce
the cost of production to a level that will
be competitive with conventional ways
of generating power. One way to
achieve this is to significantly increase
the conversion efficiency of solar cell
materials and devices.
Basically, there are two approaches to
increasing the efficiency of solar cells;
(1) Selecting the semiconductor
materials with appropriate energy gaps
to match the solar spectrum (i.e.,
between 1.1 – 1.8eV) and the
optimizing their optical, and electrical
properties;
(2) Innovative device engineering,
which enables more effective charge
collection as well as better utilization of
the solar spectrum through the use of
the emerging advance materials.
Advancement in solar cell materials development
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Polycrystalline Thin Film Solar Cell
These are solar cell made by depositing one or more thin film layers of polycrystalline
semiconductor materials on the substrate. Polycrystalline thin film solar cells are
important because of their low cost of fabrication, large areas, and the possibility of
convenient integration with other solar energy conversion devices.
 Dye-Sensitized Solar Cell
Dye-sensitized solar cells are next-generation solar cells based on innovative tech.
Unlike conventional silicon-based solar cells, dye-sensitized solar cells consist
primarily of photosensitive dye and other substances. Dye-sensitized solar cells are
able to generate electricity by converting energy from light absorbed by the dye.
 Polymer Solar Cell
Polymer solar cell is an organic photovoltaic cell that produces electricity from
sunlight using polymers. Compared to silicon-based devices, polymers are
lightweight, disposable, inexpensive to fabricate, flexible and have lower potential for
negative environmental impact. These plastic solar cells are produced by coating or
printing polymer and nano-engineered materials onto polyethylene substrate in a
continuous roll-to-roll process similar to photographic film.
 Hybrid solar cell
These are solar cells that combine advantages of both organic and inorganic
semiconductor materials.
EMDI Focus in the Area of Solar Energy Development
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As part of the effort in developing materials for efficient solar application in
Nigeria, EMDI has made significant progress in the following areas (in addition to
publications on solar cell production in reputable international journals):
Synthesis, fabrication and characterization of ternary compound based
solar cell
Ternary semiconductors, are compound semiconductor which consist of three
elements with a wide range physical properties. The physical Properties which
may vary, include band gaps, crystal lattice structures, electron and Hole
mobilities, optical properties, thermal conductivity, and so on. By selecting
appropriate ternary semiconductor materials, it becomes possible to realize
various devices, which cannot be achieved using the main elemental
semiconductor material, silicon. E.g CuAlS, CdPbS, CuSnS
A student on PhD research is presently working on using the ternary compound
for solar cell and other optoelectronic devices.
Development of micro processor controlled spin coater for thin deposition
EMDI as been able to develop a micro processor controlled spin coater for thin
film deposition.
NASENI has a 7.5MW solar panel manufacturing plant at Karshi, Abuja through
a joint venture project with a foreign partner.
The ultimate aim is to develop the technology for solar cell production in EMDI
that will feed Karshi Plant
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preparation and characterization various Nano/ Thin materials
for advance energy research
Various nano materials are being investigated for their possible
application in energy research. materials such as Dilute magnetic
semiconductor Materials (Mn: SnO2), Mn: PbO and Fe2O3,
Dielectric Material and Piezoelectric material
Preparation and characterization of conducting polymer blend
for solar cell application and other optoelectronic devices
Development of stamping methods for pattern transfer and cold
welding for polymer solar cell
Research embarked upon by one of our collaborator from Princeton
university, USA
Synthesis, fabrication and characterization of nanostructures Eu
doped ZnS light emitting diode
in collaboration with a Researcher from university of Agriculture,
Makurdi
Solar Paint
New 'solar paint' could generate electricity from the roofs and walls of EVERY
home without the need for bulky panels
'Nanocrystals' used to generate power
Can be painted or printed onto walls or windows
So tiny you could fit 250,000,000,000 on head of a pin (The nanocrystals are
about 4 nanometers in size)
Thin enough to be painted or printed onto walls
SOME OF THE FACILITIES AVAILABLE
@ EMDI FOR SOLAR-RELATED
RESEARCH WORK
THE GLOVE BOX
Glove Box is a chamber constantly supplied with nitrogen or argon to create the
needed inert atmosphere needed for work in an electronic fabrication lab.
THE SPIN COATER
“EMDI MicroCONTROLLER Spin
Coater” – GF-BB-UBmcsc01
“EMDI MicroCONTROLLER Spin
Coater” – GF-BB-UBmcsc01
Won 2 awards @ the 5th University of Lagos Research Conference and Fair held
between 21st and 23rd October, 2009. First, as the Best Exhibited Project outside the
University and the Second-Best of all exhibited projects
THE LESKER NANO-38
THERMAL DEPOSITION UNIT
Microelectronic Grade Vacuum
Oven
NanoSpec Film Thickness
Measurement System
UV-VIS SPECTROPHOTOMETER
X-RAY DIFFRACTOMETER
MICROPROCESSOR
CONTROLLED OPTICAL
MICROSCOPES
Keithley 4-POINT PROBE
SYSTEM
Conclusion
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With the level of human capacity and
facilities available at EMDI, the institute is
poised to contribute to the rapid development
of solar energy generation in Nigeria through
impartation of research based knowledge,
engineering principles and practices of
developing materials for solar energy
application which is the one of modern
technologies in solving the present energy
challenges.