The document discusses silicon nanowires and their application in solar cells. It begins by introducing semiconductor nanowires and methods of fabricating them, including bottom-up and top-down approaches. It then discusses different crystal structures of silicon used in solar cells, including crystalline, amorphous, and polycrystalline silicon. The objective is to review the application of silicon nanowires in solar cells using different silicon crystal structures. It provides literature on these topics and discusses advantages and challenges of different solar cell technologies using various silicon materials.
Flexible CIGS PV: Past, Present, and FutureSolarDan
A quick introduction to the development of lightweight, flexible, high performance CIGS solar technology at Ascent Solar. The unique value proposition of these product enables innovative design and integration solutions for novel applications in rapidly growing niche markets.
Different Generation Solar Cells
CIGS and CZTS Based Technology
Ink Based Technology
CIGS Device Structure
Making more efficient solar cells
Developing thin film technologies using alternative less costly materials and methods
Incorporate innovative cheaper deposition methods such as electrodeposition and printing technology
Optical fiber Communication training reporthuzaifa027
This is the complete report of my summer training done in optical fiber installation and technician. You will find all the stuff related to optical fiber installation.
Flexible CIGS PV: Past, Present, and FutureSolarDan
A quick introduction to the development of lightweight, flexible, high performance CIGS solar technology at Ascent Solar. The unique value proposition of these product enables innovative design and integration solutions for novel applications in rapidly growing niche markets.
Different Generation Solar Cells
CIGS and CZTS Based Technology
Ink Based Technology
CIGS Device Structure
Making more efficient solar cells
Developing thin film technologies using alternative less costly materials and methods
Incorporate innovative cheaper deposition methods such as electrodeposition and printing technology
Optical fiber Communication training reporthuzaifa027
This is the complete report of my summer training done in optical fiber installation and technician. You will find all the stuff related to optical fiber installation.
Current Status of Solar Photovoltaic Technology Platforms, Manufacturing Issu...Tuong Do
Speaker: Dr. Steven S. Hegedus, Institute of Energy Conversion, University of Delaware
In his talk, Dr. Hegedus, a 30-year solar cell research veteran, provides an overview of the existing status of today's solar technology platforms and manufacturing issues, as well as provide viewers with his perspective looking 3 to 5 years into the future. He discusses cadmium telluride (CdTe) and copper indium gallium selenide (CIGS) thin-film technology. He also provides up-to-date results for advanced crystalline silicon (c-Si) high efficiency cell technology concepts such as the amorphous/c-Si heterojunction, all-back-contact cells, selective emitters and laser-fired contacts. Finally, he briefly describes his lab's current work on addressing critical issues in CIGS and c-Si cell technology.
Dr. Hegedus has been a member of the research staff at IEC at the University of Delaware, the world's oldest photovoltaic research laboratory, since 1982. He co-edited the 1st and 2nd editions of the "Handbook of Photovoltaic Science and Engineering" (Wiley 2003, 2011) and is a co-editor of the journal "Progress in Photovoltaics."
Thursday, Sept. 27, 1 p.m. EDT
Source: http://www.photonics.com/Webinar.aspx?WebinarID=24
Developing Resilience Through Diversity in the Welsh Photovoltaic IndustryGavin Harper
Far eastern manufacturers have significantly undercut European manufacturers in the production of crystalline silicon solar cells. Some have described this as a ‘Solar Trade War’. This presents a challenging context for the European Industry as crystalline silicon technologies comprise the bulk of the marketplace. In Wales, this situation has been given particular poignancy by the closure of Sharp’s module assembly in Llay, Wrexham – where imported silicon solar cells were assembled into larger modules.
For the UK, the regional context for this industry is emerging. Competition based on labour-cost is impossible so there is a need to discover distinct regional strengths in order to stay competitive. There is an importance to focusing on products which offer a high degree of Gross Value Added. This means focusing on strategic niches and technologies that whilst not perhaps offering the highest conversion efficiency, offer attractive returns through economic competitiveness.
There are a range of other PV technology trajectories – thin-film cells and excitonic cells which occupy a much smaller proportion of the marketplace, however, whilst presently less efficient, they promise the potential of continuous production processes that may enable them to be produced more cost effectively. Furthermore, the technical properties of thin film cells lend themselves to capturing diffuse light, whereas silicon solar cells perform better with direct light. This may be considered a good fit between the technology and the weather of the regional market the technology could potentially serve!
This paper provides an analysis of Wales regional strengths in PV, the interesting diversity of research into PV technologies within Wales with a view to how the nation can retain competitiveness in this arena. The work will build on extensive analysis and involvement already undertaken CSER for the DECC UK Solar Roadmap.
In this ppt of 33 pages we just cover all the main topics of optical fiber.
In these slides you will find alll the matter helpfull.
kindely dont forget to give us a small creadit so that we will get motivated for next ppt.
we will try to provide you the best material for your studies.
for any type of help or any type of qiestions do follow me on insta my insta id is - luckyrana.lr and you can ask any type of queries in dm of insta i will definetly help you.
Thanks
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
A window on the future of solar glazingGavin Harper
This presentation looks at some of the advances in glazing incorporating Solar Photovoltaic devices in order to generate electricity. It looks at a range of technologies including Organic Solar Concentrators, Luminescent Solar Concentrators, Pythagoras Solar's unique glazing system, Dye sensitised solar cells and Honeycomb Thin Film Devices.
Quantum dots (QDs) are often referred to very tiny man-made semiconductor particles, whose size are normally no more than 10 nanometers. Their extremely small size renders their optical and electronic properties different from those of bulk materials.
https://www.cd-bioparticles.com/t/Properties-and-Applications-of-Quantum-Dots_56.html
A Comprehensive Review on Recent MPPT of a Solar PV Systems using Intelligent...ssuser793b4e
The uncertainty associated with modelling and performance of solar photovoltaic systems could be easily and efficiently solved by using Maximum power point techniques. During the past decade of 2010 to 2021, the classification of techniques based on intelligent, non- intelligent and their hybrid models are found as potential techniques for detecting the maximum power point of a photovoltaic system. In addition, for this decade there is no extensive and comprehensive review on applicability of intelligent, non-intelligent and their hybrid models for performance prediction and modelling of solar photovoltaic systems. Therefore, this article focuses on extensive review on design, modelling, maximum power point tracking, advantages, disadvantages of each technique, evolutionary trend, convergence and tracking speed, and output efficiency prediction of solar photovoltaic systems under partial shading conditions and non-partial shading conditions using intelligent, non-intelligent and their hybrid techniques. Furthermore, a total of 77 selected articles on the solar PV tracking technique and their hybrid models together with the PV technology were reviewed. Total of 22 articles are reviewed and summarized in this review paper for the period of 2010 to 2021 with 12 articles in non- intelligent technique, 7 articles in intelligent technique and 3 articles in their hybrid form. The review showed the suitability and reliability of intelligent, non-intelligent and their hybrid models for accurate detection of maximum power point and the performance characteristics of solar photovoltaic systems. Finally, this review presents the guidance for the researchers and engineers in the field of solar photovoltaic systems to select the suitable techniques for enhancement of the performance characteristics of the solar photovoltaic systems and the utilization of the available solar radiation.
Current Status of Solar Photovoltaic Technology Platforms, Manufacturing Issu...Tuong Do
Speaker: Dr. Steven S. Hegedus, Institute of Energy Conversion, University of Delaware
In his talk, Dr. Hegedus, a 30-year solar cell research veteran, provides an overview of the existing status of today's solar technology platforms and manufacturing issues, as well as provide viewers with his perspective looking 3 to 5 years into the future. He discusses cadmium telluride (CdTe) and copper indium gallium selenide (CIGS) thin-film technology. He also provides up-to-date results for advanced crystalline silicon (c-Si) high efficiency cell technology concepts such as the amorphous/c-Si heterojunction, all-back-contact cells, selective emitters and laser-fired contacts. Finally, he briefly describes his lab's current work on addressing critical issues in CIGS and c-Si cell technology.
Dr. Hegedus has been a member of the research staff at IEC at the University of Delaware, the world's oldest photovoltaic research laboratory, since 1982. He co-edited the 1st and 2nd editions of the "Handbook of Photovoltaic Science and Engineering" (Wiley 2003, 2011) and is a co-editor of the journal "Progress in Photovoltaics."
Thursday, Sept. 27, 1 p.m. EDT
Source: http://www.photonics.com/Webinar.aspx?WebinarID=24
Developing Resilience Through Diversity in the Welsh Photovoltaic IndustryGavin Harper
Far eastern manufacturers have significantly undercut European manufacturers in the production of crystalline silicon solar cells. Some have described this as a ‘Solar Trade War’. This presents a challenging context for the European Industry as crystalline silicon technologies comprise the bulk of the marketplace. In Wales, this situation has been given particular poignancy by the closure of Sharp’s module assembly in Llay, Wrexham – where imported silicon solar cells were assembled into larger modules.
For the UK, the regional context for this industry is emerging. Competition based on labour-cost is impossible so there is a need to discover distinct regional strengths in order to stay competitive. There is an importance to focusing on products which offer a high degree of Gross Value Added. This means focusing on strategic niches and technologies that whilst not perhaps offering the highest conversion efficiency, offer attractive returns through economic competitiveness.
There are a range of other PV technology trajectories – thin-film cells and excitonic cells which occupy a much smaller proportion of the marketplace, however, whilst presently less efficient, they promise the potential of continuous production processes that may enable them to be produced more cost effectively. Furthermore, the technical properties of thin film cells lend themselves to capturing diffuse light, whereas silicon solar cells perform better with direct light. This may be considered a good fit between the technology and the weather of the regional market the technology could potentially serve!
This paper provides an analysis of Wales regional strengths in PV, the interesting diversity of research into PV technologies within Wales with a view to how the nation can retain competitiveness in this arena. The work will build on extensive analysis and involvement already undertaken CSER for the DECC UK Solar Roadmap.
In this ppt of 33 pages we just cover all the main topics of optical fiber.
In these slides you will find alll the matter helpfull.
kindely dont forget to give us a small creadit so that we will get motivated for next ppt.
we will try to provide you the best material for your studies.
for any type of help or any type of qiestions do follow me on insta my insta id is - luckyrana.lr and you can ask any type of queries in dm of insta i will definetly help you.
Thanks
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
A window on the future of solar glazingGavin Harper
This presentation looks at some of the advances in glazing incorporating Solar Photovoltaic devices in order to generate electricity. It looks at a range of technologies including Organic Solar Concentrators, Luminescent Solar Concentrators, Pythagoras Solar's unique glazing system, Dye sensitised solar cells and Honeycomb Thin Film Devices.
Quantum dots (QDs) are often referred to very tiny man-made semiconductor particles, whose size are normally no more than 10 nanometers. Their extremely small size renders their optical and electronic properties different from those of bulk materials.
https://www.cd-bioparticles.com/t/Properties-and-Applications-of-Quantum-Dots_56.html
A Comprehensive Review on Recent MPPT of a Solar PV Systems using Intelligent...ssuser793b4e
The uncertainty associated with modelling and performance of solar photovoltaic systems could be easily and efficiently solved by using Maximum power point techniques. During the past decade of 2010 to 2021, the classification of techniques based on intelligent, non- intelligent and their hybrid models are found as potential techniques for detecting the maximum power point of a photovoltaic system. In addition, for this decade there is no extensive and comprehensive review on applicability of intelligent, non-intelligent and their hybrid models for performance prediction and modelling of solar photovoltaic systems. Therefore, this article focuses on extensive review on design, modelling, maximum power point tracking, advantages, disadvantages of each technique, evolutionary trend, convergence and tracking speed, and output efficiency prediction of solar photovoltaic systems under partial shading conditions and non-partial shading conditions using intelligent, non-intelligent and their hybrid techniques. Furthermore, a total of 77 selected articles on the solar PV tracking technique and their hybrid models together with the PV technology were reviewed. Total of 22 articles are reviewed and summarized in this review paper for the period of 2010 to 2021 with 12 articles in non- intelligent technique, 7 articles in intelligent technique and 3 articles in their hybrid form. The review showed the suitability and reliability of intelligent, non-intelligent and their hybrid models for accurate detection of maximum power point and the performance characteristics of solar photovoltaic systems. Finally, this review presents the guidance for the researchers and engineers in the field of solar photovoltaic systems to select the suitable techniques for enhancement of the performance characteristics of the solar photovoltaic systems and the utilization of the available solar radiation.
Huge demand of silicon in photovoltaic cells caused a shortage of silicon which results in demand
for new technology in this field and so another revolutionary cheap method is innovated namely thin film solar
cell. In this paper, various types of thin film solar cells are reviewed. They have less efficiency and also low cost
compared to 1st generation solar cell. They are based on silicon Thin film implies that less material is used
which makes the solar cells cheaper.
Advancements in Photovoltaic Materials for Sustainable Energy GenerationChristo Ananth
Christo Ananth, Rajini K R Karduri, "Advancements in Photovoltaic Materials for Sustainable Energy Generation", International Journal of Advanced Research in Basic Engineering Sciences and Technology (IJARBEST), Volume 7,Issue 1,January 2021,pp 28-38
This ppt gives you the basic introduction, talks about it's inception, the basic physics behind it and mainly the fabrication process and after that it discusses the uses and future prospects of it.
Advance Solar Cells and Printed Solar Cell A Reviewijtsrd
Solar cell technology begin with first generation and third generation solar cells is discussed here by considering different advanced materials on which these technologies are based. The efficiencies attained with different new age solar cell technologies, limitations in their commercial application is overcome with the new technology used in solar cell. This paper is an overview of the advances technology used in solar cell and printed solar cell. Sukhjinder Singh | Nitish Palial | Rohit Kumar "Advance Solar Cells and Printed Solar Cell: A Review" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-7 | Issue-5 , October 2023, URL: https://www.ijtsrd.com/papers/ijtsrd59981.pdf Paper Url: https://www.ijtsrd.com/engineering/electrical-engineering/59981/advance-solar-cells-and-printed-solar-cell-a-review/sukhjinder-singh
Applications of SiC-Based Thin Films in Electronic and MEMS DevicesMariana Amorim Fraga
Mariana Amorim Fraga, Rodrigo Sávio Pessoa, Marcos Massi and Homero Santiago Maciel (2012). Applications of SiC-Based Thin Films in Electronic and MEMS Devices, Physics and Technology of Silicon Carbide Devices, Dr. Yasuto Hijikata (Ed.), InTech, DOI: 10.5772/50998. Available from: https://www.intechopen.com/books/physics-and-technology-of-silicon-carbide-devices/applications-of-sic-based-thin-films-in-electronic-and-mems-devices
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
2. 1.Introduction
Semiconductor nanowires are 1-D structures where the magnitude of the
semiconducting material is confined to a length of less than 100nm.
Semiconductor nanowires can be fabricated by a range of methods which
can be categorised into one of two patterns, bottom-up or top-down.
Bottom-up processes can be defined as those where structures are
assembled from their sub-components in an additive fashion.
11/04/2019 2
3. Cont’d
Top-down fabrication strategies use sculpting or etching to carve structures from
a larger piece of material in a subtractive fashion
A silicon nanowire is an extended single crystal of silicon with a diameter of tens
to a few hundred nanometres and with a length of several micrometres.
Both solar cell and nanowire research have become hot topics within science
and engineering.
The need for higher solar cell efficiencies at lower cost has become apparent, and
at the same time synthetic control in nanoscience has improved such that high
performance electronic devices are becoming possible.
11/04/2019 3
4. Objective
The objective of this seminar work was to review the application of
silicon nanowire for solar cells/photovoltaic cells for different crystal
structure of silicon.
11/04/2019 4
5. 2. LITERATURE REVIEW
Silicon is one of the most abundant elements in the Earth’s crust.
It is usually found in the form of oxides and silicates, such as sand
and quartz.
Possibly one of the more important and multipurpose elements,
silicon can be used to produce everything from elements to computer
chips.
Silicon is the basis for current electronics and photovoltaic, so it is the
most widely studied and described semiconductor.
11/04/2019 5
6. 2.1.2. Crystalline silicon
Crystalline silicon(c-Si) forms the basis of many of today’s
integrated circuits as it is a readily available semiconductor which is
relatively easy to process and dope to form semiconductor devices.
Devices made from crystalline silicon include many integrated
circuits, diodes or solar cells.
High purity crystalline silicon is typically produced using the
Czochralski process (Lide, 2005).
11/04/2019 6
7. 2.1.2 Amorphous silicon
Amorphous silicon (a-Si) is a glass like materials that
structurally does not have long rang structural order and is
randomly oriented.
Due to the random orientation of the material, the absorption
coefficient of light in amorphous silicon tends to be higher than
that of crystalline silicon.
This allows thin film devices to be fabricated from amorphous
silicon that can absorb similar quantities of light to much thicker
crystalline silicon slices.
11/04/2019 7
8. Cont’d
One of the main uses of amorphous silicon is in the solar cell
industry for the fabrication of cheap thin film solar cells.
In addition it is a relatively straightforward process to create doped
layers of amorphous silicon.
The dopant layers can be produce by introducing dopant gases
during the deposition of amorphous silicon.
11/04/2019 8
9. 2.1.3. Polycrystalline silicon
Polycrystalline silicon is variant of silicon that consists of a series of
small crystallites that have grown together with an extremely high
crystallinity or proportion of crystalline material.
Typically, polycrystalline silicon is defined as having a grain size
(cryatallite diameter) of between 10 and 30 micrometres and a
crystalline fraction of close to 100% (Cabrrocas, 2004).
11/04/2019 9
10. 2.2. Silicon nanowire
A nanowire is a nanostructure, with the diameter of the order of a
nanometer (10−9 meters).
Alternatively, nanowires can be defined as structures that have a
thickness or diameter constrained to tens of nanometers or less and an
unconstrained length.
Many different types of nanowires exist, including metallic (e.g., Ni,
Pt, Au), semiconducting (e.g., Si, InP, GaN, etc.), and insulating (e.g.,
SiO2, TiO2).
11/04/2019 10
11. Cont’d
Several growth mechanisms are used to describe the growth of silicon
nanowires.
The most widely used of these is vapour liquid solid (VLS) mechanism.
This was first proposed by Wagner and Ellis in 1964 and uses a liquid
metal catalyst to aid the growth.
Gold is the catalyst most frequently used although some other catalysts,
such as titanium, have also used.
11/04/2019 11
13. 2.3. Application of silicon nanowires
2.3.1 Photovoltaic cells/ solar cells
The photovoltaic effect was first reported by Edmund Becquerel in
1839 when he observed that the action of light on a silver coated
platinum electrode immersed in electrolyte produced an electric
current.
A solar cell (also called a photovoltaic cell) is an electrical device
that converts the energy of light directly into electricity by the
photovoltaic effect.
11/04/2019 13
14. Cont’d
There are a number of different ways to produce solar cells and a range
of materials from which they can be produced.
Silicon is a commonly used semiconductor material for producing
solid state solar cells.
Solar cells producing using silicon have different properties when they
are made using different types of silicon.
11/04/2019 14
16. Cont’d
Solar cells are often electrically connected and encapsulated as a
module.
Photovoltaic modules often have a sheet of glass on the front (sun
up) side, allowing light to pass while protecting the semiconductor
wafers from abrasion and impact due to wind-driven debris, rain,
hail, etc.
11/04/2019 16
17. Cont’d
Solar cells convert three-quarters of the energy contained in the Sun‘s
spectrum into electricity yet the infrared spectrum is entirely lost in
standard solar cells.
In contrast, black silicon solar cells are specifically designed to
absorb this part of the Sun‘s spectrum – and researchers have recently
succeeded in doubling their overall efficiency.
11/04/2019 17
18. Cont’d
Much of the early use of silicon photovoltaic was in power supply
systems for space vehicle.
However, in recent times, there is an increasing market for
photovoltaic remote area power supplies and in distributed
generators on the electricity grid.
11/04/2019 18
19. Cont’d
In the marketplace there are several types of solar cell technologies
available including crystalline, microcrystalline, nanocrytalline and
amorphous silicon.
The world market is currently dominated by crystalline silicon solar
cells which held some 90.9% of the market in 2004 and 93.5% in 2005
(Singh and Jennings, 2007).
11/04/2019 19
20. 2.3.1.1. Crystalline solar cells
Traditionally most solar cells have been made from doped crystalline
semiconductors such as crystalline silicon (c-Si).
Crystalline semiconductors have a very well defined structure with
both a high long range and high short range order.
The characteristics of crystalline solar cells include a well-defined
band gap and high quantum efficiency.
11/04/2019 20
21. Cont’d
However, style of cell is very expensive.
It is also time consuming to make involving as it does wafers of
single crystal.
These drawbacks and the rising costs of solar grade crystalline
silicon have encouraged the development of other materials
particularly thin film for solar cells.
11/04/2019 21
22. 2.3.1.2. Nanocrystalline solar cells
o Thin film solar cells can be produced using nanocrystalline silicon as
core component.
o Nanocrystalline silicon solar cells have been produced using a
combination of amorphous silicon and nanocrystalline silicon in triple
junction device.
11/04/2019 22
23. Cont’d
o Nanocrystalline silicon films have recently attracted attention for use
in photovoltaics solar cells since they show promise for providing an
approach that results in lower cost and higher efficiency than the
conventional solar cells.
o Its wider band gap is much more suitable for solar cell applications
than the narrow indirect band gap of single crystalline silicon.
11/04/2019 23
24. Cont’d
o In addition crystalline silicon has low absorption coefficient and narrower
band gap that desired for solar cell applications.
o Solar light with energy much larger than the band gap, when absorbed by
the materials is converted into heat rather than electricity thus reducing the
efficiency.
11/04/2019 24
25. 2.3.1.3. Amorphous silicon solar cell
• Amorphous silicon (a-Si) has been used as a photovoltaic solar cell
material for devices which require very little power, such as pocket
calculators, because their lower performance compared to traditional
c-Si solar cells is more than offset by their simplified and lower cost
of deposition onto a substrate.
11/04/2019 25
26. 2.4. Band gap
The band gap also known as the optical gap, energy gap or mobility
gap, is an important properties of semiconductors that determines the
optoelectronics properties of devices created from such
semiconductors.
The band gap is the minimum amount energy needed for an electron
to jump from the valence band to the conduction band is as shown in
figure below.
11/04/2019 26
27. Cont’
11/04/2019 27
Schematic of the semiconductor band gap showing the valance band,
conduction band and mid gap states (Parlevliet, 2008)
28. Cont’d
Photovoltaic devices, the band gap energy needs to be close to the peak of
the energy range of visible light (1eV to 3eV) or the spectrum of light
emitted by the sun.
11/04/2019 28
29. 2.4.1. Types of band gap
In semiconductor physics, the band gap of a semiconductor is always one of
two types, a direct band gap or an indirect band gap.
11/04/2019 29
Indirect band gapDirect band gap
30. 3.Conclusion
The Monocrystalline silicon cell is produced from pure silicon.
Since the Monocrystalline silicon is pure and defect free, the
efficiency of cell will be higher.
In polycrystalline solar cell, liquid silicon is used as raw material
and polycrystalline silicon was obtained followed by solidification
process.
11/04/2019 30
31. Cont’d
Amorphous silicon was obtained by depositing silicon film on the
substrate like glass plate.
The efficiency of amorphous cells is much lower than that of the
other two cell types.
As a result, they are used mainly in low power equipment, such as
watches and pocket calculators, or as facade elements.
11/04/2019 31