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Dear all,

has anyone more information and critical knowledge about the state of  
this art?

There should be other groups researching OPV's...   ?    What are the  
difficulties?
Are these things fragile?
This piece of news arrives at the time when all car headlights become  
LED's.   BIG market...

Interesting to see that the University professors already created a  
commercial company!

Hugs,
Maurice

Maurice Bazin
Praia do Flamengo 82,  Apt 1001
Flamengo
22210-030   Rio de janeiro

Tel:   21 2557 0929
Cell phone:   21  9465 0167


Em 27/08/2008, às 07:18, Sam Anderson escreveu:

Web address: http://www.sciencedaily.com/releases/2008/08/080821212854.htm 
  	

Scientists are working with new materials that can make devices used  
for converting sunlight to electricity cheaper and more efficient

ScienceDaily (Aug. 25, 2008) — Scientists are working to convert  
sunlight to cheap electricity at South Dakota State University.  
Research scientists are working with new materials that can make  
devices used for converting sunlight to electricity cheaper and more  
efficient.

Assistant professor Qiquan Qiao in SDSU’s Department of Electrical  
Engineering and Computer Science said so-called organic photovoltaics,  
or OPVs, are less expensive to produce than traditional devices for  
harvesting solar energy.

Qiao and his SDSU colleagues also are working on organic light- 
emitting diodes, or OLEDs.

The new technology is sometimes referred to as “molecular electronics”  
or “organic electronics” — organic because it relies on carbon-based  
polymers and molecules as semiconductors rather than inorganic  
semiconductors such as silicon.

“Right now the challenge for photovoltaics is to make the technology  
less expensive,” Qiao said.

“Therefore, the objective is find new materials and novel device  
structures for cost-effective photovoltaic devices.

“The beauty of organic photovoltaics and organic LEDs is low cost and  
flexibility,” the researcher continued. “These devices can be  
fabricated by inexpensive, solution-based processing techniques  
similar to painting or printing."

“The ease of production brings costs down, while the mechanical  
flexibility of the materials opens up a wide range of applications,”  
Qiao concluded.

Organic photovoltaics and organic LEDs are made up of thin films of  
semiconducting organic compounds that can absorb photons of solar  
energy. Typically an organic polymer, or a long, flexible chain of  
carbon-based material, is used as a substrate on which semiconducting  
materials are applied as a solution using a technique similar to  
inkjet printing.

“The research at SDSU is focused on new materials with variable band  
gaps,” Qiao said.

“The band gap determines how much solar energy the photovoltaic device  
can absorb and convert into electricity.”

Qiao explained that visible sunlight contains only about 50 percent of  
the total solar energy. That means the sun is giving off just as much  
non-visible energy as visible energy.

“We’re working on synthesizing novel polymers with variable band gaps,  
including high, medium and low-band gap varieties, to absorb the full  
spectrum of sunlight. By this we can double the light harvesting or  
absorption,” Qiao said.

SDSU’s scientists plan to use the variable band gap polymers to build  
multi-junction polymer solar cells or photovoltaics.

These devices use multiple layers of polymer/fullerene films that are  
tuned to absorb different spectral regions of solar energy.

Ideally, photons that are not absorbed by the first film layer pass  
through to be absorbed by the following layers.

The devices can harvest photons from ultraviolet to visible to  
infrared in order to efficiently convert the full spectrum of solar  
energy to electricity.

SDSU scientists also work with organic light-emitting diodes focusing  
on developing novel materials and devices for full color displays.

“We are working to develop these new light-emitting and efficient,  
charge-transporting materials to improve the light-emitting efficiency  
of full color displays,” Qiao said.

Currently, LED technology is used mainly for signage displays. But in  
the future, as OLEDs become less expensive and more efficient, they  
may be used for residential lighting, for example.

The new technology will make it easy to insert lights into walls or  
ceilings. But instead of light bulbs, the lighting apparatus of the  
future may look more like a poster, Qiao said.

Qiao and his colleagues are funded in part by SDSU’s electrical  
engineering Ph.D. program and by National Science Foundation and South  
Dakota EPSCoR, the Experimental Program to Stimulate Competitive  
Research.

In addition Qiao is one of about 40 faculty members from SDSU, the  
South Dakota School of Mines and Technology and the University of  
South Dakota who have come together to form Photo Active Nanoscale  
Systems (PANS).

The primary purpose is developing photovoltaics, or devices that will  
directly convert light to electricity.
Adapted from materials provided by South Dakota State University, via  
Newswise.