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Research team is looking to make solar panels more efficient and give LEDs color changing capability

A pair of researchers at Arizona State University has announced a new advancement in making nanowires that could one day lead to significantly more efficient solar panels and LED lighting that is color changeable. The engineers who made the advance are Cun-Zheng Ning and Alian Pan.

The pair are working on ways to improve the quaternary alloy semiconductor nanowire raw materials. The nanowires the pair work with are nanometers in diameter and tens of microns in length. They are made from four elements, typically by alloying two or more compound semiconductors.

The researchers say that the band gap is the most important thing that controls how solar panels absorb sunlight and what color light LEDs produce. The more available band gaps for solar panels, the more of the spectrum of light panels will be able to absorb. With LEDs, more band gaps mean more colors of light can be produced. 

The big hurdle for the researchers is that naturally occurring and manmade semiconductors today only have a specific band gap. The only way to widen the band gap available to the semiconductor is to compound two or more semiconductors. The trick to accomplishing the alloy of semiconductors is that they two have to have a lattice with similar inter-atomic spaces to match and be grown together.

Ning said, "This is why we cannot grow alloys of arbitrary compositions to achieve arbitrary band gaps. This lack of available band gaps is one of reasons current solar cell efficiency is low, and why we do not have LED lighting colors that can be adjusted for various situations."

So far, the team has been able to create a zinc sulfide and cadmium selenide alloy to produce a quaternary semiconductor – this is the first time that a quaternary semiconductor has been produced in the form of a nanowire or nanoparticle. The team is now studying the application and use of the quaternary alloy materials for making solar cells and has developed a lateral multi-cell design panel.



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Small correction
By tbhuang2 on 3/22/2010 1:08:05 PM , Rating: 3
I'm taking a class on solid state semiconductor devices right now. There is one small and subtle but important correction that should be made in your article. The sentence that reads:
"The only way to widen the band gap available to the semiconductor is to compound two or more semiconductors."
Should read, "The only way to CHANGE the band gap available to the semiconductor..."
Any material possesses only 1 band gap energy value. This cannot change. But by alloying with other materials of different band gap energies, you can achieve a value somewhere in between, but still only ONE band gap energy. I believe what you meant by "widen" was to widen the range of band gap energies possible. To anyone familiar with the subject, to "widen the band gap" would mean to increase the value of the band gap energy, which would be a bad thing as that would increase the minimum light wave frequency threshold of absorbed light--which would absorb less light, not more.




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