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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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RE: Promises promises
By JediJeb on 3/22/2010 5:52:10 PM , Rating: 2
quote: So? Even if you double my initial estimate, its still only 1/50 the amount of land you need, even ignoring the vast amounts extra needed due from energy storage and transmission losses. Again, to do what? What do you think the proposal is suggesting?

I have to agree with Spoofe here, that is a valid argument if you are trying to supply the total electricity the US needs, but if you are trying to offset some then it is more than sufficient. It is like saying to provide the total US electricity supply with hydroelectric you would need to flood an entire state. The original idea was to offset some energy needs, that of a large city, not an entire country. But if you were using this only to offset NYC then yes you would need the 50K miles of transmission lines, but to offset the amount of electricity NYC uses but spread across several large cities then it would not be such a problem.

quote: Huh? Look at any current Interstate overpass. I do. Regularly. It's called "shade". It looks darker in pictures due to contrast and poor dynamic range. It's NOT "in the dark" as you suggest, nor does it necessitate lighting.

Here I would also expect the sides to not be touching the ground, if they are 20feet high then a lot of light is going to get under them. Also the added benefit of a shaded highway would reduce gasoline consumption in summer as the A/C would not be working as hard to combat the heat of the sun on the cars, and personally I prefer not driving in super bright sunlight, as the dimmer light of an overcast day is much easier on my eyes when driving so this would help also. Dry pavement versus wet pavement driving is also something to consider. Reduction of cost due to snow removal in winter and no road salts needed also helps not to mention less corrosion of vehicles from said salts.

Can't overlook the side advantages to this idea. I doubt it would ever be fiscally feasible but not totally without merit.

RE: Promises promises
By porkpie on 3/22/2010 6:13:25 PM , Rating: 2
"but if you are trying to offset some then it is more than sufficient."

If you're trying to offset just 1-2% of our electric needs by spending tens of trillions of dollars, then yes, this is more than sufficient.

"Reduction of cost due to snow removal in winter..."

If you don't remove the snow from the solar panels, how do they generate electricity? You can simply slant them...but you'd need a pitch close to 10:12 to reliably shed snow. Not only does that reduce efficiency -- even in summer months -- but it means a peak height of 105 feet for a 100' wide highway. That's a big structure to build 50,000 miles of.

"Can't overlook the side advantages to this idea."

Sure, there are some. There are also far more side disadvantages that I didn't even mention. Things like do you work on solar panels above a highway filled with rapidly moving vehicles? Stop traffic? Or build the panels strong enough to be walked on from above? (adding even more to the cost).

Face the facts. Using the "free space" above highways would be far more expensive than just using some undeveloped land somewhere. It's just not a practical idea.

"I'm an Internet expert too. It's all right to wire the industrial zone only, but there are many problems if other regions of the North are wired." -- North Korean Supreme Commander Kim Jong-il

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