‘Artificial leaves’ produce electricity

A North Carolina State University-led team has created ‘artificial leaves – water-gel-based solar devices which can act like solar cells to generate electricity.

The devices show it’s possible to make solar cells that more closely mimic nature, and could also be less expensive and more environmentally friendly than current silicon-based solar cells.

The flexible devices are made of a water-based gel infused with light-sensitive molecules – one version uses plant chlorophyll – combined with electrodes coated with carbon materials such as carbon nanotubes or graphite.

The light-sensitive molecules become excited by the sun’s rays to produce electricity – in a similar way to plant molecules which become excited to synthesize sugars and grow.

Lead author professor Orlin Velev of NCSU says 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 easy to use because of the devices’ water-gel matrix.

Now that they’ve proven the concept, Velev says the researchers will work to fine-tune the 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 suggests that in future, roofs could be covered 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 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.”