Friday, July 30, 2010

Breakthrough in Thin-Film Solar Cells


Scientists at Johannes Gutenberg University Mainz (JGU) in Mainz have made a major breakthrough in their search for more efficient thin-film solar cells. Computer simulations designed to investigate the so-called indium/gallium puzzle have highlighted a new way of increasing the efficiency of CIGS thin-film solar cells. Researchers to date have achieved only about 20% efficiency with CIGS cells although efficiency levels of 30% are theoretically possible.

Thin-film solar cells are gaining an ever increasing proportion of the solar cell market. As they are only a few micrometers thick, they offer savings on material and manufacturing costs. Currently, the highest level of efficiency of about 20% is achieved by CIGS thin-film solar cells, which absorb the sunlight through a thin layer made of copper, indium, gallium, selenium, and sulphur. However, the levels of efficiency achieved to date are nowhere near the levels theoretically possible.

The research team at Mainz University headed by Professor Dr Claudia Felser is using computer simulations to investigate the characteristics of CIGS, whose chemical formula is Cu(In,Ga)(Se,S)2. This research forms part of the comCIGS project funded by the Federal German Ministry for the Environment, Nature Conservation, and Nuclear Safety (BMU). IBM Mainz and Schott AG are collaborating with the Johannes Gutenberg University Mainz, the Helmholtz Center Berlin for Materials and Energy and Jena University in the project that is targeted at finding ways of optimizing CIGS solar cells. The researchers focused in particular on the indium/gallium puzzle that has been baffling scientists for years: Although it has been postulated on the basis of calculations that the optimal indium:gallium ratio should be 30:70, in practice, the maximum efficiency level has been achieved with the exactly inverse ratio of 70:30.

With the support of IBM Mainz, Christian Ludwig of Professor Felser's team undertook new calculations with the help of a hybrid method in which he used a combination of density functional calculations and Monte Carlo simulations. "Density functional calculations make it possible to assess the energies of local structures from the quantum mechanical point of view. The results can be used to determine temperature effects over wide length scale ranges with the help of Monte-Carlo simulations," Dr Thomas Gruhn, head of the theory group in Professor Felser's team, explains the methods used. Christian Ludwig is able to use a mainframe for his investigations that was recently donated to Mainz University by IBM as part of a Shared University Research (SUR) science award.

Production at high temperatures promotes homogeneity of the material

With the aid of the simulations, it was discovered that the indium and gallium atoms are not distributed evenly in the CIGS material. There is a phase that occurs at just below normal room temperature in which the indium and gallium are completely separate. If the material is heated to above this demixing temperature, differently sized clusters of indium and gallium atoms do form. The higher the temperature, the more homogeneous the material becomes. It has now become apparent that gallium-rich CIGS is always less homogeneous than indium-rich CIGS. Because of this lack of homogeneity, the optoelectronic properties of the gallium-rich material are poorer, resulting in the low efficiency levels of gallium-rich CIGS cells -- an effect that has now been explained for the first time. The calculations also provide a concrete indication of the best way to manufacture CIGS solar cells. If it is produced at higher temperatures, the material is significantly more homogeneous. To retain the desired homogeneity, the material then needs to be cooled down sufficiently rapidly.

In practice, it was the limited heat resistance of the glass used as a substrate for solar cells that has always restricted process temperatures, but a significant breakthrough has also recently been made here. Schott AG has developed a special glass with which the process temperature can be increased to well above 600°C. The cells that result from this process are considerably more homogeneous, meaning that the production of cells with a much greater efficiency level has become possible. But the comCIGS project researchers are already thinking ahead of this. "We are currently working on large-format solar cells which should outperform conventional cells in terms of efficiency," states Gruhn. "The prospects look promising."

The work of the scientists in Mainz, conducted as part of the federal government-funded comCIGS project, has been published in the latest edition of the journal Physical Review Letters.


Journal Reference:

1.Christian Ludwig, Thomas Gruhn, Claudia Felser, Tanja Schilling, Johannes Windeln, Peter Kratzer. Indium-Gallium Segregation in CuIn_{x}Ga_{1-x}Se_{2}: An Ab Initio%u2013Based Monte Carlo Study

10 comments:

Anonymous said...

Erreur #2 : branchez redactor

my blog post :: tirage de tarot de marseille gratuit

mmjiaxin said...

air max 90
prada outlet
chanel outlet store
louis vuitton handbags
kobe shoes
rolex watches
hollister uk
fitflops outlet sale
north face outlet
nhl jerseys
moncler outlet
canada goose outelt
coach outlet store
ghd uk
mulberry outlet store
air jordan shoes for sale
toms outlet
longchamp handbags
michael kors outlet
hermes outlet store
mm1202

Chenzhen 20160303chenzhen said...

louis vuitton purses
replica rolex watches
michael kors handbags
prada handbags
michael kors outlet online
ugg boots
retro jordans 13
kids lebron shoes
kate spade handbags
adidas originals store
ray ban outlet
kobe 8
marc jacobs outlet
jordan 6s
ralph lauren outlet
nike store uk
ralph lauren outlet
ugg outlet
ray ban sunglasses outlet
coach outlet online
basketball shoes
louis vuitton purses
adidas superstar shoes
abercrombie clothing
lebron 12
louis vuitton bags
timberlands
louis vuitton purses
louis vuitton outlet stores
coach outlet online
air jordan 8
coach outlet online
tods sale
oakley outlet
nike store
michael kors outlet
coach outlet online
cheap toms
longchamp outlet
mcm handbags
20160330chenzhen

mmjiaxin said...

michael kors outlet online
adidas nmd
http://www.tiffanyand.co.uk
michael kors outlet clearance
http://www.oakleyoutlet-store.com
http://www.michaeljordanshoes.us.com
adidas nmd runner
authentic jordans
chrome hearts online
michael kors outlet
tiffany and co
fitflops
ray ban uk,cheap ray ban sunglasses
michael kors purses
fitflops
cheap jordans online
michael kors handbags
adidas nmd
nike huarache
louis vuitton handbags
nfl jerseys wholesale
nfl jerseys from china
cheap oakley sunglasses
cheap real jordans
michael kors outlet
adidas nmd uk
nike huarache
michael kors handbags clearance
links of london outlet store
michael kors outlet
cheap uggs
cheap air jordan
yeezy boost 350
kobe shoes,kobe zoom,nike zoom kobe
nike air huarache
gg

Gege Dai said...

oakley sunglasses
tory burch outlet
ferragamo outlet
louis vuitton handbags
ray ban sunglasses
pandora outlet
futbol baratas
coach outlet clearance
kobe 9
cazal sunglasses
ralph lauren polo
oakley sunglasses
burberry outlet store
air max 90
ugg boots
ugg outlet
beats by dre
chaussure louboutin
beats by dr dre
nike roshe
beats headphones
lacoste polo shirts
michael kors online
coach outlet online
ugg boots on sale
longchamp outlet
true religion jeans
tory burch outlet
louis vuitton handbags outlet
ray ban sunglasses
canada goose jackets
true religion jeans
ralph lauren pas cher
chicago blackhawks jerseys
nike mercurial
ralph lauren polo
0808jianxiang

fangyaoting said...

fangyanting20160919
nike roshe
calvin klein underwear
coach outlet canada
hermes outlet
mulberry outlet
pandora jewelry
adidas wings
true religion outlet
true religion jeans
michael kors outlet

raybanoutlet001 said...

nike roshe run one
michael kors handbags,michael kors handbags clearance,michael kors clearance
michael kors handbags
ray ban sunglasses
adidas yeezy boost
tiffany jewelry
tiffany jewelry

兮兮 said...

20161021 junda
coach outlet
lebron james shoes
ralph lauren uk
nike trainers
michael kors wholesale
toms shoes
polo ralph lauren
uggs on sale
nike outlet
timberland boots

chenlina said...

cheap ugg boots
christian louboutin pas cher
louis vuitton
timberland boots
uggs clearance
ugg boots
michael kors outlet
michael kors outlet
ray ban wayfarer
pandora jewelry
chenlina20161115

aaa kitty20101122 said...

cheap jordans
longchamp handbags
yeezy boost 350
yeezy
michael kors
adidas ultra boost
adidas ultra boost uncaged
chrome hearts
lacoste outlet
hogan outlet online

New and Renewable Energy

New and Renewable Energy
Your source for the New and Renewable Energy News and Technologies