Metamaterial antireflective coating on solar cell - a review
Published on: Mar 3, 2016
Transcripts - Metamaterial antireflective coating on solar cell - a review
IDEAZ (NANOTECHNOLOGY DEPARTMENT)
Udit kumar (COG14/03257) Sourabh hirau (COG14/08151)
IIT Roorkee IIT Roorkee
Contact no – 8979523753 8126130183
Metamaterial Antireflective coating on Solar cell –A review article
Energy is the key issue these days, fossil fuels is our major sources of energy. Following the
current rate of consumption of fossil fuel, it will last in next 30-50 years. Energy is the
backbone of industrialized economy. Nuclear power is costly and risky. So many countries
have shown their interests in renewable sources of energy.
Now a day solar energy has emerged as a potential source of energy. There are different ways
to harness and use solar energy. Solar cell is one of the best ways to harness; it directly
converts solar energy to electrical energy. On an average single p-n junction solar cell
efficiency is not more than 20%. As it cannot use the whole solar spectrum; making a high
efficiency solar cell is always a challenging task. A lot of work has been done to choose an
appropriate semiconductor for appropriate energy gaps to match complete solar spectrum.
There is multi-junction solar cell which gives us better utilization of the solar spectrum.
Metamaterial has a huge advantage in this field. These are the artificially engineered
materials with property not found in nature. These materials are extremely useful in
controlling the path of the light. Many authors were intended to propose Metamaterials as
antireflective coating with traditional p-n junction solar cell.
The current anti-reflective technologies are classified into three broad categories
1. The film anti-reflective coatings
2. Micron-scale Texturing and light trapping
3. Sub-wavelength surface texturing
The most common technique used today is the use of thin film-reflective coatings (ARCs).
These coatings are used to minimise reflectance almost completely at a particular wavelength
through destructive interference of reflected light. Double or even multi-layer ARCs are also
used to minimise reflection over multiple frequencies.
Micron scale texturing and light trapping is also a potential mean of antireflection through
utilization of “double bounce” effect. In this light reflected from one part of textured surface
is directed onto another part of the surface and light incident more than once on solar cell.
Now a day Metamaterial is used to serve this purpose (but with different mechanism).
Metamaterial –an introduction
A Metamaterial is a macroscopic/nano composite of periodic or non-periodic structure,
whose function is due to both the artificial cellular architecture and chemical composition.
These materials exhibit some properties, which are not usually shown by the naturally
By using artificial structure we attain negative permeability and also permittivity, earlier it
only works in microwave region of light but with nano level structures now it works in
visible frequencies too.
Generally they are left-handed material.
Negative reflective index materials
It happens due to the simultaneous existence of
1. Negative permeability
2. Negative permittivity
A typical Metamaterial
The resonating wires give the material The resonating loops give the material
negative permeability negative permittivity
The resonating wire and resonating loops has the most critical role in Metamaterials. Wires is
for electrical response and resonating loops are for magnetic response, together they give us
negative reflective index as shown in figure. Generally it is the structure which play key role
in deciding the property of Metamaterial.
Metamaterials application in solar cell
• Photonic metamaterial is used in multi band solar cell.
• In designing high efficiency solar cell (composite metamaterial)
• light trapping applications
• Anti-reflective coatings
Metamaterial as antireflective coating
Many pioneering works has been done in this area few of them are described below
Metamaterials of Sawtooth Structure According to Nicholas X. Fang, the Brit (1961) and
Alex (1949) d’Arbeloff, Associate Professor of the Department of Mechanical Engineering,
MIT, the thinnest materials used to fully capture light are limited to a very narrow range of
wavelengths and the angles of incidence. They proposed a design composed of a pattern of
wedge-shaped ridges whose widths are precisely tuned to slow and capture light of a wide
range of wavelengths and the angles of incidence. These Metamaterials could be made
extremely thin, saving weight and cost. Also, Kin Hung Fung, an MIT postdoc has proposed
a design of multilayer sawtooth structure to absorb a wide range of frequencies with an
efficiency of more than 95 percent.
Fig: Sawtooth Tapered ridges, made from alternating layers of metal and insulating material
deposited on a surface, can produce a metamaterial that is tuned to a range of specific
frequencies of light. Light of different wavelengths is absorbed by the material at different
levels, where the light's wavelength matches the width of the ridges. Designed in MIT’s
Department of Mechanical Engineering
A simple si solar cell works in breakdown region when photon respective to the band gap
falls on it leads to charge separation and one electron goes into the conduction band from
valence band and that way we get current
Fig: a simple p-n junction solar cell
(Not getting into detail of solar cell working) The kind of solar cell used commonly without
any anti reflective coating are quiet less efficient.
Figure-5: showing solar panel installed in a area
Efficiency calculation some commonly used solar cell without antireflective coating are
Disclaimer – The data provided in the tables are based on good faith on the authors.
The above data show clearly the efficiency of commonly used solar cell is not more than 20%
in almost all type of cell.
Solar cell with antireflective coating
Metamaterial anti reflective coating is applied to enhance the performance of solar cell
Fig: showing a schematic diagram of multi junction solar cell with anti-reflective coating
Efficiency of solar cell after coating are described below
The % reflectance and transmittance characteristics with frequency of light ha show above,
which clearly will result into significant increase in efficiency
Above chart shows light absorption due to different type of metamaterial coating
Metamaterial artificially engineered material is very useful in manipulating the path of light
and take advantage of it. We observe a significant rise in absorption coefficient after applying
antireflective coating which leads to better efficiency of solar cell.
1. Martin A. Green, Keith Emery, Yoshihiro Hishikawa, Wilhelm Warta and Ewan D.
Dunlop, Solar cell efficiency tables (version 39), Published online in Wiley Online
Library (wileyonlinelibrary.com). DOI: 10.1002/pip.2163.
2. Satyen K. Deb, Recent developments in highefficiency pv cells, National Renewable
3. Laboratory. P. J. Reddy, Science and Technology of Photovoltaics, 2nd edition, CRC
Press, Leiden (2010).
4. http://web.mit.edu/newsoffice/2012/metamaterialabsorbs- light-0309.html.
5. Yang Liu, Yitung Chen and Jichun Li, Solar cell design using metamaterials, UNLV
Center for Energy Research.
6. Soteris A. Kalogirou, Solar Energy Engineering Processes and Systems, Academic Press,
Elsevier -2009 edition.
7. Yanxia Cui, Kin Hung Fung, Jun Xu, Hyungjin Ma, Yi Jin, Sailing He, and Nicholas X.
Fang, Ultrabroadband Light Absorption by a Sawtooth Anisotropic Metamaterial Slab,
8. Thomas Henry Hand, Design and Applications of Frequency Tunable and Reconfigurable
9. Metamaterials, Phd thesis, Department of Electrical and Computer Engineering Duke
10. 9. Umit cotuk, Scattering from multi-layered metamaterials using wave matrices, master’s
11. naval postgraduate school.
12. 10. Shridhar E. Mendhe & Yogeshwar Prasad Kosta, Metamaterial properties and
13. international Journal of Information Technology and Knowledge Management January-
14. Volume 4, No. 1, pp. 85-89.
15. 11. Victor Veselago, Leonid Braginsky, Valery Shklover, and Christian Hafner, Negative
Refractive Index Materials, Journal of Computational and Theoretical Nanoscience Vol.3,
16. 12. S. Fonash, "A Manual for AMPS-1D for Windows 95/NT", The Pennsylvania State