Discovery challenges accepted wisdom on organic PV

Scientists at Warwick University have found, contrary to previously accepted wisdom about the design of organic PV devices, electrode layers with only a 1% conductive surface area can still be ‘fully effective’ at extracting charges generated in an organic semiconductor layer.

The discovery, according to the university, opens up new possibilities for electrode materials in such devices, and could allow for the development of flexible PV devices that could be applied to curved surfaces.

The research, explained in the paper An Electrode Design Rule for Organic Photovoltaics Elucidated Using a Low Surface Area Electrode, published in Advanced Functional Materials, is based on experimentation using a model electrode which the researchers could systematically change the surface of. The results showed even when 99% of the electrode layer’s surface was electrically insulating, the device did not register a reduction in performance provided the conducting regions were not positioned too far apart. The paper’s abstract explains spacing of the conducting areas was less than or equal to twice the optimal thickness of the cell layer.

Lower cost

“This new finding means composites of insulators and conducting nano-particles such as carbon nanotubes, graphene fragments or metal nanoparticles, could have great potential for this purpose, offering enhanced device performance or lower cost,” said Dinesha Dabera, research fellow at the University of Warwick. “Organic solar cells are very close to being commercialized but they’re not quite there yet, so anything that allows you to further reduce cost whilst also improving performance is going to help enable that.”

Given organic PV’s potential for flexible solar on buildings, vehicles and other applications, the researchers noted, widening the range of materials available to cell designers could improve their ability to meet aesthetic requirements.

“There is a fast growing need for solar cells that can be supported on flexible substrates that are lightweight and color-tunable,” said Ross Hatton, of the University of Warwick’s chemistry department. “This discovery may help enable these new types of flexible solar cells to become a commercial reality sooner.”