MATERIALS DEVELOPMENT FOR MATERIALS DEVELOPMENT FOR SOLAR ENERGY APPLICATIONSOLAR ENERGY APPLICATION

21/02/2011

By

Dr. S.O.O. Olusunle, R.Eng., MASME, FMSNAg Director/Chief Executive, Engineering Materials Development

Institute, Akure

at a Public Lecture organized byThe Metallurgical, Mining and Materials Division of the Nigerian Society of Engineers

OUTLINEOUTLINE BackgroundBackground IntroductionIntroduction Solar EnergySolar Energy Harvesting Solar EnergyHarvesting Solar Energy EMDI Effort on Solar Energy DevelopmentEMDI Effort on Solar Energy Development Available Facilities @ EMDIAvailable Facilities @ EMDI ConclusionConclusion

BackgroundBackground About 80% of Africa’s 1 billion population is engulfed in abject About 80% of Africa’s 1 billion population is engulfed in abject

poverty and is lacking virtually in all areas of human poverty and is lacking virtually in all areas of human

developmentdevelopment

Access to energy plays a central role in solving the poverty Access to energy plays a central role in solving the poverty

debacledebacle

Africa is referred to as a “dark continent” because about 70% Africa is referred to as a “dark continent” because about 70%

of the population do not have access to electric lighting.of the population do not have access to electric lighting.

Over 1.6 billion people in developing countries do not have Over 1.6 billion people in developing countries do not have

access to electricity and have no hope of being connected to access to electricity and have no hope of being connected to

the national grid in the near future (World Bank, 1996).the national grid in the near future (World Bank, 1996).

IntroductionIntroduction Fossil fuels provide around 66% of the world's electrical Fossil fuels provide around 66% of the world's electrical

power, and 95% of the world's total energy demands.power, and 95% of the world's total energy demands. Global warming (green house effect) and climate Global warming (green house effect) and climate

changes are due to the use of these fossil fuels like changes are due to the use of these fossil fuels like coal, oil and gas.coal, oil and gas.

by-products of fossil fuels such as carbon dioxide, by-products of fossil fuels such as carbon dioxide, sulfur and nitrogen oxide may result in acid rainsulfur and nitrogen oxide may result in acid rain

Sourcing for clean, efficient, and sustainable energy is Sourcing for clean, efficient, and sustainable energy is therefore a necessitytherefore a necessity

solar energy stands out because the source is solar energy stands out because the source is unlimited and available everywhereunlimited and available everywhere

Solar EnergySolar Energy Solar energy is the energy directly from the sun which is Solar energy is the energy directly from the sun which is

one of the most important non-conventional energy one of the most important non-conventional energy sources available for man’s use. sources available for man’s use.

It is clean, renewable and free source of energy largely It is clean, renewable and free source of energy largely available in sufficient quantity available in sufficient quantity

Man can harness the energy for useful purposes by Man can harness the energy for useful purposes by means of active and passive devices among which are means of active and passive devices among which are solar cells and photothermal converters. solar cells and photothermal converters.

However, the challenges of solar power generation are its However, the challenges of solar power generation are its production cost and storage. The primary objective of the production cost and storage. The primary objective of the worldwide research and development is to reduce the cost worldwide research and development is to reduce the cost of generating solar energy to a level that will be of generating solar energy to a level that will be competitive with conventional ways of generating power.competitive with conventional ways of generating power.

HistoryHistory Humans have harnessed the power of the sun for millennia. Humans have harnessed the power of the sun for millennia. In the fifth century B.C., the Greeks took advantage of passive In the fifth century B.C., the Greeks took advantage of passive

solar energy by designing their homes to capture the sun’s heat solar energy by designing their homes to capture the sun’s heat during the winter. during the winter.

Later, the Romans improved on solar architecture by covering Later, the Romans improved on solar architecture by covering south-facing windows with clear materials such as mica or glass, south-facing windows with clear materials such as mica or glass, preventing the escape of solar heat captured during the daypreventing the escape of solar heat captured during the day

In the 1760s, Horace de Saussure built an insulated rectangular In the 1760s, Horace de Saussure built an insulated rectangular box with a glass cover that became the prototype for solar box with a glass cover that became the prototype for solar collectors used to heat water. The first commercial solar water collectors used to heat water. The first commercial solar water heaters were sold in the U.S. in the late 1890sheaters were sold in the U.S. in the late 1890s

In the late 19th century, inventors and entrepreneurs in Europe In the late 19th century, inventors and entrepreneurs in Europe and the U.S. developed solar energy technology that would form and the U.S. developed solar energy technology that would form the basis of modern designsthe basis of modern designs

ProductionProduction Sunlight can be converted into heat and electricity Sunlight can be converted into heat and electricity

in a number of ways. in a number of ways. A variety of solar technologies are in production, A variety of solar technologies are in production,

and many companies and researchers are and many companies and researchers are pursuing efforts to develop devices that convert the pursuing efforts to develop devices that convert the sun’s energy more efficientlysun’s energy more efficiently

Energy from the sun is harvested using either Energy from the sun is harvested using either photothermal conversion system which converts photothermal conversion system which converts solar radiation into heat energy or solar cell which solar radiation into heat energy or solar cell which convert radiation from the sun directly to electricity.convert radiation from the sun directly to electricity.

Materials for Harvesting Solar EnergyMaterials for Harvesting Solar Energy

Energy from the sun is harvested using either photothermal Energy from the sun is harvested using either photothermal conversion system which converts solar radiation into heat conversion system which converts solar radiation into heat energy or solar cell which convert radiation from the sun directly energy or solar cell which convert radiation from the sun directly to electricity. to electricity.

The development of materials for solar energy harvesting is The development of materials for solar energy harvesting is based on the use of solar radiation and profound understanding of based on the use of solar radiation and profound understanding of the materials properties at the atomic scale levels. the materials properties at the atomic scale levels.

MaterialMaterial structure-property relations enable the evolution of structure-property relations enable the evolution of tailored-made materials for these applications. To achieve this tailored-made materials for these applications. To achieve this objective, it requires the combination of experiments (i.e., objective, it requires the combination of experiments (i.e., materials synthesis, characterization of structural and processing materials synthesis, characterization of structural and processing of thin film for both solar cells and photo thermal conversion), of thin film for both solar cells and photo thermal conversion), theoretical analysis which cover modeling of the entire system.theoretical analysis which cover modeling of the entire system.

Development of Photo thermal ConverterDevelopment of Photo thermal Converter Photothermal converter is device developed Photothermal converter is device developed

using special materials that absorb solar using special materials that absorb solar

radiation and convert it to heat energy. radiation and convert it to heat energy.

The high efficiency photothermal material The high efficiency photothermal material

implies maximum absorption of incident solar implies maximum absorption of incident solar

radiation with a minimum thermal and optical radiation with a minimum thermal and optical

loss. loss.

The temperatures ranging from ambient to The temperatures ranging from ambient to

1000°C are achievable in a photothermal 1000°C are achievable in a photothermal

converter made of good selective materials, converter made of good selective materials,

such as black nickel, black chrome, multi-layer such as black nickel, black chrome, multi-layer

tandem stacks and some other composite tandem stacks and some other composite

semiconductor materials which are good semiconductor materials which are good

absorber (low reflection) of solar radiation and absorber (low reflection) of solar radiation and

poor emitter of thermal radiation. poor emitter of thermal radiation.

The temperatures above ambient are used in The temperatures above ambient are used in

various applications such as space heating, various applications such as space heating,

water heating, and distillation and drying. water heating, and distillation and drying.

Solar Box cooker

Solar furnance at Odeillo, FranceMax Temp 3800°C

Solar water heater

Solar Cell DevelopmentSolar Cell Development

A solar cell is a semiconductor device that converts sunlight directly into A solar cell is a semiconductor device that converts sunlight directly into electric current using the principle of photovoltaic (PV) effect. electric current using the principle of photovoltaic (PV) effect.

The effect is made by partnering p-type and n-type semiconductor. The The effect is made by partnering p-type and n-type semiconductor. The semiconductors are selected such that they absorb significant portion of semiconductors are selected such that they absorb significant portion of the solar spectrum. the solar spectrum.

The absorbed photon gives rise to Electron-Hole pairs. These excess The absorbed photon gives rise to Electron-Hole pairs. These excess carriers are swept across the junction by the electric field and are carriers are swept across the junction by the electric field and are collected at the contacts. This gives rise to photocurrent and can be collected at the contacts. This gives rise to photocurrent and can be made to deliver power to a load. made to deliver power to a load.

Thus the important steps in solar energy conversion are absorption of Thus the important steps in solar energy conversion are absorption of radiation, generation of carriers, diffusion of majority carriers, separation radiation, generation of carriers, diffusion of majority carriers, separation of minority carriers by the electric field and collection of carriers at the of minority carriers by the electric field and collection of carriers at the contact. contact.

Historically, solar cells are used as an alternative source for generating Historically, solar cells are used as an alternative source for generating electric power, such as remote area power systems, handheld electric power, such as remote area power systems, handheld calculators, and water pumps. calculators, and water pumps.

However, a major barrier impeding the development of large-scale However, a major barrier impeding the development of large-scale power application of PV systems is the high price of commercially power application of PV systems is the high price of commercially available solar cell modules. available solar cell modules.

Photovoltaic EnergyPhotovoltaic Energy

• Silicon based photovoltaic cells represent 90% of Silicon based photovoltaic cells represent 90% of the photovoltaic panels presently sold in the world. the photovoltaic panels presently sold in the world.

• More than one third of the cost is due to the silicon More than one third of the cost is due to the silicon itself. Indeed, its purification, crystallization and the itself. Indeed, its purification, crystallization and the wafer fabrication have an important energetic and wafer fabrication have an important energetic and economical cost. economical cost.

• The photovoltaic research community is looking for The photovoltaic research community is looking for solar cell structure based on thinner silicon layers. solar cell structure based on thinner silicon layers.

• However, the thinner the material, the lower its light However, the thinner the material, the lower its light absorption, especially at long wavelengths (near absorption, especially at long wavelengths (near infrared).infrared).

So the primary objective of solar cell So the primary objective of solar cell research and development is to reduce research and development is to reduce the cost of production to a level that will the cost of production to a level that will be competitive with conventional ways be competitive with conventional ways of generating power. One way to of generating power. One way to achieve this is to significantly increase achieve this is to significantly increase the conversion efficiency of solar cell the conversion efficiency of solar cell materials and devices. materials and devices.

Basically, there are two approaches to Basically, there are two approaches to increasing the efficiency of solar cells;increasing the efficiency of solar cells;

(1) Selecting the semiconductor (1) Selecting the semiconductor materials with appropriate energy gaps materials with appropriate energy gaps to match the solar spectrum (i.e., to match the solar spectrum (i.e., between 1.1 – 1.8eV) and the between 1.1 – 1.8eV) and the optimizing their optical, and electrical optimizing their optical, and electrical properties; properties;

(2) Innovative device engineering, which (2) Innovative device engineering, which enables more effective charge collection enables more effective charge collection as well as better utilization of the solar as well as better utilization of the solar spectrum through the use of the spectrum through the use of the emerging advance materials.emerging advance materials.

Polycrystalline Thin Film Solar CellPolycrystalline Thin Film Solar Cell

These are solar cell made by depositing one or more thin film layers of polycrystalline 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 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 important because of their low cost of fabrication, large areas, and the possibility of convenient integration with other solar energy conversion devices. convenient integration with other solar energy conversion devices.

Dye-Sensitized Solar CellDye-Sensitized Solar Cell

Dye-sensitized solar cells are next-generation solar cells based on innovative tech. Dye-sensitized solar cells are next-generation solar cells based on innovative tech. Unlike conventional silicon-based solar cells, dye-sensitized solar cells consist Unlike conventional silicon-based solar cells, dye-sensitized solar cells consist primarily of photosensitive dye and other substances. Dye-sensitized solar cells are 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. able to generate electricity by converting energy from light absorbed by the dye.

Polymer Solar CellPolymer Solar Cell

Polymer solar cell is an organic photovoltaic cell that produces electricity from Polymer solar cell is an organic photovoltaic cell that produces electricity from sunlight using polymers. Compared to silicon-based devices, polymers are sunlight using polymers. Compared to silicon-based devices, polymers are lightweight, disposable, inexpensive to fabricate, flexible and have lower potential for lightweight, disposable, inexpensive to fabricate, flexible and have lower potential for negative environmental impact. These plastic solar cells are produced by coating or negative environmental impact. These plastic solar cells are produced by coating or printing polymer and nano-engineered materials onto polyethylene substrate in a printing polymer and nano-engineered materials onto polyethylene substrate in a continuous roll-to-roll process similar to photographic film.continuous roll-to-roll process similar to photographic film.

Hybrid solar cellHybrid solar cell

These are solar cells that combine advantages of both These are solar cells that combine advantages of both organic and inorganic and inorganic semiconductor materials.semiconductor materials.

Advancement in solar cell materials development

EMDI Focus in the Area of Solar Energy DevelopmentEMDI Focus in the Area of Solar Energy Development As part of the effort in developing materials for efficient solar application in Nigeria, 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 EMDI has made significant progress in the following areas (in addition to publications on solar cell production in reputable international journals):publications on solar cell production in reputable international journals):

Synthesis, fabrication and characterization of ternary compound based solar Synthesis, fabrication and characterization of ternary compound based solar cellcell

Ternary semiconductors, are compound semiconductor which consist of three Ternary semiconductors, are compound semiconductor which consist of three elements with a wide range physical properties. The physical Properties which may elements with a wide range physical properties. The physical Properties which may vary, include band gaps, crystal lattice structures, electron and Hole mobilities, vary, include band gaps, crystal lattice structures, electron and Hole mobilities, optical properties, thermal conductivity, and so on. By selecting appropriate ternary optical properties, thermal conductivity, and so on. By selecting appropriate ternary semiconductor materials, it becomes possible to realize various devices, which semiconductor materials, it becomes possible to realize various devices, which cannot be achieved using the main elemental semiconductor material, silicon. E.g cannot be achieved using the main elemental semiconductor material, silicon. E.g CuAlS, CdPbS, CuSnSCuAlS, CdPbS, CuSnS

A student on PhD research is presently working on using the ternary compound for A student on PhD research is presently working on using the ternary compound for solar cell and other optoelectronic devices.solar cell and other optoelectronic devices.

Development of micro processor controlled spin coater for thin depositionDevelopment of micro processor controlled spin coater for thin deposition

EMDI as been able to develop a micro processor controlled spin coater for thin film EMDI as been able to develop a micro processor controlled spin coater for thin film deposition.deposition.

NASENI has a 7.5MW solar panel manufacturing plant at Karshi, Abuja through a NASENI has a 7.5MW solar panel manufacturing plant at Karshi, Abuja through a joint venture project with a foreign partner.joint venture project with a foreign partner.

The ultimate aim is to develop the technology for solar cell production in EMDI that The ultimate aim is to develop the technology for solar cell production in EMDI that will feed Karshi Plantwill feed Karshi Plant

preparation and characterization various Nano/ Thin materials preparation and characterization various Nano/ Thin materials for advance energy researchfor advance energy research

Various nano materials are being investigated for their possible Various nano materials are being investigated for their possible application in energy research. materials such as Dilute magnetic application in energy research. materials such as Dilute magnetic semiconductor Materials (Mn: SnO2), Mn: PbO and Fe2O3, semiconductor Materials (Mn: SnO2), Mn: PbO and Fe2O3, Dielectric Material and Piezoelectric materialDielectric Material and Piezoelectric material

Preparation and characterization of conducting polymer blend Preparation and characterization of conducting polymer blend for solar cell application and other optoelectronic devicesfor solar cell application and other optoelectronic devices

Development of stamping methods for pattern transfer and cold Development of stamping methods for pattern transfer and cold welding for polymer solar cellwelding for polymer solar cell

Research embarked upon by one of our collaborator from Princeton Research embarked upon by one of our collaborator from Princeton university, USAuniversity, USA

Synthesis, fabrication and characterization of nanostructures Eu Synthesis, fabrication and characterization of nanostructures Eu doped ZnS light emitting diode doped ZnS light emitting diode

in collaboration with a Researcher from university of Agriculture, in collaboration with a Researcher from university of Agriculture, MakurdiMakurdi

Solar PaintSolar PaintNew 'solar paint' could generate electricity from the roofs and walls of EVERY home without the need for bulky panels

'Nanocrystals' used to generate powerCan be painted or printed onto walls or windowsSo 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 SOME OF THE FACILITIES AVAILABLE @ EMDI FOR SOLAR-RELATED @ EMDI FOR SOLAR-RELATED

RESEARCH WORKRESEARCH WORK

THE GLOVE BOXTHE 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 COATERTHE SPIN COATER

““EMDI MicroCONTROLLER Spin EMDI MicroCONTROLLER Spin Coater” – GF-BB-UBmcsc01Coater” – GF-BB-UBmcsc01

““EMDI MicroCONTROLLER Spin EMDI MicroCONTROLLER Spin Coater” – GF-BB-UBmcsc01Coater” – 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 THE LESKER NANO-38 THERMAL DEPOSITION UNITTHERMAL DEPOSITION UNIT

Microelectronic Grade Vacuum Microelectronic Grade Vacuum OvenOven

NanoSpec Film Thickness NanoSpec Film Thickness Measurement System Measurement System

UV-VIS SPECTROPHOTOMETERUV-VIS SPECTROPHOTOMETER

X-RAY DIFFRACTOMETERX-RAY DIFFRACTOMETER

MICROPROCESSOR MICROPROCESSOR CONTROLLED OPTICAL CONTROLLED OPTICAL

MICROSCOPESMICROSCOPES

Keithley 4-POINT PROBE Keithley 4-POINT PROBE SYSTEMSYSTEM

ConclusionConclusion

With the level of human capacity and With the level of human capacity and facilities available at EMDI, the institute is facilities available at EMDI, the institute is poised to contribute to the rapid development poised to contribute to the rapid development of solar energy generation in Nigeria through of solar energy generation in Nigeria through impartation of research based knowledge, impartation of research based knowledge, engineering principles and practices of engineering principles and practices of developing materials for solar energy developing materials for solar energy application which is the one of modern application which is the one of modern technologies in solving the present energy technologies in solving the present energy challenges.challenges.