Method for Cheaper Quantum Dots

Research by Michael Wong (left) and Rice University scientists at Rice's Center for Biological and Environmental Nanotechnology (CBEN), today revealed a breakthrough method for producing molecular specks of semiconductors called quantum dots, a discovery that could clear the way for better, cheaper solar energy panels.

Quantum dots interact with light in unique ways, to give off different-colored light or to create electrons and holes, due partly to their tiny size, partly to their shape and partly to the material they're made of. Rice scientists have developed a new chemical method for making four-legged cadmium selenide quantum dots, which previous research has shown to be particularly effective at converting sunlight into electrical energy.

Quantum dots are "megamolecules" of semiconducting materials that are smaller than living cells. Prior research by others has shown that four-legged quantum dots, which are called tetrapods, are many times more efficient at converting sunlight into electricity than regular quantum dots. But, principal investigator Michael Wong, assistant professor of chemical and biomolecular engineering said the problem is that there is still no good way of producing tetrapods. Current methods lead to a lot of particles with uneven-length arms, crooked arms, and even missing arms. Even in the best recipe, 30 percent of the prepared particles are not tetrapods, he said.

CBEN's formula produces same-sized particles, in which more than 90 percent are tetrapods. The essence of the new recipe is to use cetyltrimethylammonium bromide instead of the standard alkylphosphonic acid compounds. Cetyltrimethylammonium bromide happens to be safer – it's used in some shampoos, for example – and it's much cheaper than alkylphosphonic acids. For producers looking to eventually ramp up tetrapod production, this means cheaper raw materials and less purification steps, Wong said.

The research, by Wong and his graduate student Subashini Asokan with CBEN Director Vicki Colvin and graduate student Karl Krueger appears this week in the journal Small.

Comments

[Ross]

At this point, I'm a little thankful that I use a bar of soap (actual "soap" made from alkali, vegetable oil and a little aloe) to wash my hair.

I look at my wife's bottle of shampoo and I'm happy to admit that she's braver than me in some ways...

[Greg woulf]

This is really good news. It takes us from marginal to competitive, and with the added incentive of being clean, quiet and possibly remote.

I think the concern over what all this nano-material stuff will do in regards to health is justified. I don't think it applies to this topic so much individually though. If anything, Quantam dots are safer than other nano-materials, because they'll be sealed in.

I think this is a very good step.

[GreyFlcn]

Whoa, this is big.

If CIGS thinfilm can integrate with this.

We'd have 20% effecient solar panels at 1/10th the cost.

Gimme gimme gimme! :P

[TheSunHarvest.com]

Great steps for a clean self sufficant future.

[GreyFlcn]

Ooh look!

We already have 20% effecient thinfilm panels.

Just requires thin strips of silver foil instead of stainless steel foil.

http://jcwinnie.biz/wordpress/?p=2176

[thomas marihart]

seeing as the chinese are already installing solar at ~$5.50/watt without gov incentives, and are poised to triple their capacity to produce PV for either domestic or intl markets (they're at about ~.5GW today), we'd better get our collective act together in North America.

The Rice tech is a nice 'shoe in' licensing agreement for nanosolar with their related technology.

I figure this breakthrough lends itself better to screen printing type technologies rather that CIGS and sputtering type manufacturing tech....again...nanosolar related.

[Green Assassin Brigade]

There have been so many anouncements recently, silver applied to thin film raising efficiency to 13-15%,

http://www.theage.com.au/news/National/New-cells-to-deliver-cheaper-solar-power/2007/05/01/1177788136933.html

Quantum dots, the article does not give a %

Solar Concentrators

Cheaper silicon,

Veggie dyes,

Is there a good comparative workup of these technologies, their comparative cost, efficiencies, need for exotic materials, etc?

They all sound wonderful but they all fail to compare to each other in ways that are meaningful to the consumer, size, cost, output. It certainly looks like a waste for many people to buy now rather than wait for one of these to come thru big.

[kit p]

The problem with doing a LCA on solar is that they just document that solar is not green. If you want to buy an expensive electronic device, buy a big TV. If you want to save energy, do not turn it on.

So what is the difference between a TV that is off and solar panels, 5%. This is the capacity factor of you solar panels.

[vakul]

A lot of hyping is going around based on short term experimental results. NY times called it Watt com. Amorphous materials undergo continuous change.They are in unstable condition,affected by heat. Check your solar powered calculators you bought years back. How many are still powered by solar energy? Two decades back NASA studied this for providing energy for water pumps in Upper Volta. I read that report. After many thoughtful analyses NASA decided on crystalline Silicon. So called nanomaterials in solutions were once called colloids. Collloid chemists know well that the surface of colloids are affected by the environment and they have to be stabilized.What is the stabilizer in these nanoparticles? Believe me that nothing can beat wafers of single crystal silicon.

[Gautam K Das]

Kindly post me more details on the solar energy tapping ( at present density is 4 to 7 kwh per square meter)devices developed based on 'quantum dot'. Thank you very much for the break through.

Best Regards. Gautam K Das
gd35@hotmail.com or gautamkd@gmail.com

[Solidea Bonina]

All sounds great!! So just a simple and useful question : Where can I buy these quantum dots for one low price to do experiment in out lab ? I need to know!

[Arseny]

Melben - colloidal quantum dots

The company offers to realize a wide range of semiconducting crystalline nanoparticles – quantum dots, synthesized through colloidal method.

http://eng.melben.ru/about/index.php

[Mark]

I'm happy new technologies are developing but disappointed that no one seems to care what these things are made of. Cadmium is pretty toxic (similar to mercury). How long will the panels last? What will we do with them when they are exhausted? Do you want to live next to the plant that produces these panels or next to the landfill where they are disposed of?

[Asics shoes]

This is very cute. I think that I am going to give it a try. thanks

[Online Furniture Stores]

This is so fascinating, but I really don't understand quantum dots... I guess it is something new to research on line.