New solar cell self-repairs like natural plant systems

January 4, 2011 by Emil Venere
Jong Hyun Choi, an assistant professor of mechanical engineering at Purdue, and doctoral student Benjamin Baker use fluorescent imaging to view a carbon nanotube. Their research is aimed at creating a new type of solar cell designed to self-repair like natural photosynthetic systems. The approach might enable researchers to increase the service life and reduce costs for photoelectrochemical cells, which convert sunlight into electricity. Credit: Purdue University photo/Mark Simons

( -- Researchers are creating a new type of solar cell designed to self-repair like natural photosynthetic systems in plants by using carbon nanotubes and DNA, an approach aimed at increasing service life and reducing cost.

"We've created artificial photosystems using optical to harvest that is converted to electrical power," said Jong Hyun Choi, an assistant professor of mechanical engineering at Purdue University.

The design exploits the unusual of structures called single-wall carbon nanotubes, using them as "molecular wires in light harvesting cells," said Choi, whose research group is based at the Birck Nanotechnology and Bindley Bioscience centers at Purdue's Discovery Park.

"I think our approach offers promise for industrialization, but we're still in the basic research stage," he said.

Photoelectrochemical cells convert sunlight into electricity and use an - a liquid that conducts electricity - to transport electrons and create the current. The cells contain light-absorbing dyes called chromophores, chlorophyll-like molecules that degrade due to exposure to sunlight.

"The critical disadvantage of conventional is this degradation," Choi said.

The new technology overcomes this problem just as nature does: by continuously replacing the photo-damaged dyes with new ones.

"This sort of self-regeneration is done in plants every hour," Choi said.

The new concept could make possible an innovative type of photoelectrochemical cell that continues operating at full capacity indefinitely, as long as new chromophores are added.

Findings were detailed in a November presentation during the International Mechanical Engineering Congress and Exhibition in Vancouver. The concept also was unveiled in an online article featured on the Web site for SPIE, an international society for optics and .

The talk and article were written by Choi, doctoral students Benjamin A. Baker and Tae-Gon Cha, and undergraduate students M. Dane Sauffer and Yujun Wu.

The carbon nanotubes work as a platform to anchor strands of DNA. The DNA is engineered to have specific sequences of building blocks called nucleotides, enabling them to recognize and attach to the chromophores.

"The DNA recognizes the dye molecules, and then the system spontaneously self-assembles," Choi said

When the chromophores are ready to be replaced, they might be removed by using chemical processes or by adding new DNA strands with different nucleotide sequences, kicking off the damaged dye molecules. New chromophores would then be added.

Two elements are critical for the technology to mimic nature's self-repair mechanism: molecular recognition and thermodynamic metastability, or the ability of the system to continuously be dissolved and reassembled.

The research is an extension of work that Choi collaborated on with researchers at the Massachusetts Institute of Technology and the University of Illinois. The earlier work used biological chromophores taken from bacteria, and findings were detailed in a research paper published in November in the journal Nature Chemistry.

However, using natural chromophores is difficult, and they must be harvested and isolated from bacteria, a process that would be expensive to reproduce on an industrial scale, Choi said.

"So instead of using biological chromophores, we want to use synthetic ones made of dyes called porphyrins," he said.

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5 / 5 (1) Jan 04, 2011
incredible :)
1.7 / 5 (6) Jan 04, 2011
"This sort of self-regeneration is done in plants every hour," Choi said

Regeneration - the implications should be obvious.

If there wasn't any regeneration how would the plants survive whilst it was busy evolving the ability to regenerate?

If there already was available regenerative abilities what on earth would it be for? Waiting for some useful function to fulfill?

Evolution as understood to be from one cell/organism to all organisms is simply impossible. Plain and simple. I invite the naysayers to explain how it could be.

Plants were created with their abilities intact, "evolution" not required.
not rated yet Jan 04, 2011
Reminds me of when the Borg Queen tells Data that the Borg are made of the best of biology and technology.
5 / 5 (3) Jan 04, 2011
If there wasn't any regeneration how would the plants survive whilst it was busy evolving the ability to regenerate?

If there already was available regenerative abilities what on earth would it be for? Waiting for some useful function to fulfill?

You obviously aren't putting any effort at all into trying to understand evolution. You falsely believe that if evolution is true then your religion must be false and that puts up a mental shield, blocking you from even considering evolution. It's unfortunate.

We're talking about regeneration at the cellular level. This is pretty much how all cells operate. They expel waste and "regenerate" from raw materials floating around. This is just basic cell behavior. There are more complex regenerations, like when lizards lose their tails, they grow new ones. It's easier to understand regeneration than that of non-regeneration. As embryos grow limbs and organs, according to their genetic code.

5 / 5 (4) Jan 04, 2011

Parts grow out to fill out what's missing... it's just now genetics works. We don't yet fully understand the mechanics of how this works, but we (collective "we", not "me") are understanding this more and more. When a limb is cut off (think lizards tail or starfish), the natural growth of the cells at the cutoff point just naturally continue to grow, as they do in an embryo. But, this is not the kind of regeneration they're talking about in the article... it's more of the cellular regeneration.

Does this help answer your question? I don't ask that smugly. I truly want to help answer your questions, but I want to be sure you're truly interested in learning.
not rated yet Jan 04, 2011
I used to like this site - till i realized it tends to be a sounding board for three arguements

1) AGW -- at least one arguement a day
2) Creationism vs Evolution -- take a philosophy class and leave it there
3) crappy article writing

of course #3 is justified on this type of site
5 / 5 (3) Jan 04, 2011
Are we still arguing irreducible complexity? Kev, organisms posses abilities. Mutations occur. Mutations can cause previously existing features to recombine and perform a new function. This is exactly how the bacterial flagellum has evolved. There was no half flagellum. Existing bacterial features mutated into the existing form. Watch Dr. Ken Millers video on YouTube.
not rated yet Jan 05, 2011
Watch Dr. Ken Millers video on YouTube.

I'd like to hear back from you Kev after you watch these videos, please.
not rated yet Jan 05, 2011
Let's make this easy enougt! This: is qood video about so called "irreducible complexity".
not rated yet Jan 05, 2011
Any hope we can get back to the article at hand?

Stories like this always torment me. We're given a taste of a technology that could potentially be a "game-changer", but with only vague speculation as to whether this would ever be practical on a mass market scale. I would like concrete analysis on if this technology will ever be used in a real world setting.

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