‘Artificial Leaves’ Gaining Power

Thursday, October 14, 2010 @ 09:10 AM gHale

Water-gel-based solar devices, “artificial leaves,” can act like solar cells to produce electricity.
The findings prove the concept for making solar cells that more closely mimic nature. They also have the potential to be less expensive and more environmentally friendly than the current standard-bearer: Silicon-based solar cells.
The bendable devices consist of water-based gel infused with light-sensitive molecules – the researchers used plant chlorophyll in one of the experiments – coupled with electrodes coated by carbon materials, such as carbon nanotubes or graphite. The light-sensitive molecules get “excited” by the sun’s rays to produce electricity, similar to plant molecules that get excited to synthesize sugars in order to grow, said Dr. Orlin Velev, North Carolina State University Invista Professor of Chemical and Biomolecular Engineering and the lead author of a paper.
The research team hopes to “learn how to mimic the materials by which nature harnesses solar energy,” Velev said. Although synthetic light-sensitive molecules can work, Velev said naturally derived products – like chlorophyll – can also easily integrate in these devices because of their water-gel matrix.
Now that they’ve proven the concept, Velev said the researchers will work to fine-tune the water-based photovoltaic devices, making them even more like real leaves.
“The next step is to mimic the self-regenerating mechanisms found in plants,” Velev said. “The other challenge is to change the water-based gel and light-sensitive molecules to improve the efficiency of the solar cells.”
Velev even imagines a future where you can cover roofs with soft sheets of similar electricity-generating artificial-leaf solar cells.
“We do not want to overpromise at this stage, as the devices are still of relatively low efficiency and there is a long way to go before this can become a practical technology,” Velev said. “However, we believe that the concept of biologically inspired ‘soft’ devices for generating electricity may in the future provide an alternative for the present-day solid-state technologies.”

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