Leaf veins inspire self-replenishing organic solar cell design

In a new paper, North Carolina State University researchers Orlin Velev and Hyung-Jun Koo show that creating solar cell devices with channels that mimic organic vascular systems can effectively reinvigorate solar cells whose performance deteriorates due to degradation by the sun’s ultraviolet rays.

Solar cells based on organic systems hold the potential to be less expensive and more environmentally friendly than silicon-based solar cells, the current industry standard.

The design of NC State’s regenerative solar cell mimics nature by use of microfluidic channels.

The devices are a type of dye-sensitized solar cells (DSSCs), composed of a water-based gel core, electrodes, and light-sensitive, organic dye molecules that capture light and generate electric current.

However, the dye molecules that get excited by the sun’s rays to produce electricity eventually degrade and lose efficiency, Velev said in a statement, and need to be replenished to reboot the device’s effectiveness in harnessing the power of the sun.

‘Organic material in DSSCs tends to degrade, so we looked to nature to solve the problem,’ Velev said. ‘We considered how the branched network in a leaf maintains water and nutrient levels throughout the leaf. Our microchannel solar cell design works in a similar way. Photovoltaic cells rendered ineffective by high intensities of ultraviolet rays were regenerated by pumping fresh dye into the channels while cycling the exhausted dye out of the cell. This process restores the device’s effectiveness in producing electricity over multiple cycles.’

Velev, Invista Professor of Chemical and Biomolecular Engineering at NC State and the lead author of a paper in Scientific Reports describing the research, added that the new gel-microfluidic cell design was tested against other designs, and that branched channel networks similar to the ones found in nature worked most effectively.