Water-gel-based solar devices, what researchers liken to "artificial leaves", can act like solar cells to produce electricity, bringing technology a bit closer to solar cells that more closely mimic the efficiency of nature and farther from the disaster of today that advocates want mandated and subsidized for questionable benefit.

If it pans out, they will be less expensive and more environmentally friendly than silicon-based solar cells.

The bendable artificial leaves are composed of water-based gel infused with light-sensitive molecules – the researchers even used plant chlorophyll in one of the experiments – coupled with electrodes coated by carbon materials, like 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, says NC State's Dr. Orlin Velev, Invista Professor of Chemical and Biomolecular Engineering and the lead author of a paper describing this new generation of solar cells.

Velev says that the research team hopes to "learn how to mimic the materials by which nature harnesses solar energy." Although synthetic light-sensitive molecules can be used, Velev says naturally derived products – like chlorophyll – are also easily integrated in these devices because of their water-gel matrix.

Now that they've proven the concept, Velev says the researchers will work to fine-tune the water-based photo-voltaic devices, making them even more like real leaves.

"The next step is to mimic the self-regenerating mechanisms found in plants," Velev says. "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 roofs could be covered with soft sheets of similar electricity-generating artificial-leaf solar cells.

"We do not want to over-promise 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 says. "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."

Citation: Hyung-Jun Koo, Suk Tai Chang, Joseph M. Slocik, Rajesh R. Naik and Orlin D. Velev, 'Aqueous soft matter based photovoltaic devices', J. Mater. Chem., 2011, Advance Article  
DOI: 10.1039/C0JM01820A