Flexible dye-sensitised solar cell may power future Air Force unmanned aerial vehicles

Wednesday, July 15, 2009

WASHINGTON - Scientists are hopeful that future Air Force unmanned aerial vehicles (UAVs) will be powered by dye-sensitized solar cells (DSSCs), which appear to be an optimum energy harvesting source, and thus may lead to longer flight times without refuelling.


Led by Dr. Minoru Taya, the University of Washington’s Multidisciplinary University Research Initiative (MURI) project team is working on airborne solar cells by using a flexible film and a thin glass coating with transparent conductive electrodes.

The researchers have thus far observed that DSSCs made from organic materials, which use dyes and moth-eye film, can catch photons and convert them into synthesized electrons that can harvest high photon energy.

They have revealed that dye-sensitised solar cells were mounted on the wings of a toy airplane some years ago, but despite the propeller being effectively powered, the plane was not able to become airborne because the glass-based solar cells they were using were too heavy.

Upon experimentation, they decided to use film battery technology, which worked and in fact, enabled the plane to fly.

“These kinds of solar cells have more specific power convergence efficiency (PCE), very clean energy and easy scalability to a larger skin area of the craft, as well as, low-temperature processing, which leads to lower costs overall,” said Taya.

The researchers are presently trying to develop DSSCs with higher PCEs using bioinspired dyes, which are installed in the wings of the UAV (airborne energy harvesters).

“Any airborne energy harvester must satisfy additional requirements, like weight and durability in airborne environments. If those are met, then there may even be longer UAV flight times,” said Taya.

The team, meanwhile, are researching into the challenges of DSSCs’ technology, and trying to determine how durable they are and how well their technology may integrate with other Air Force vehicles.

They are also trying to determine how to build the solar cells in the wing surface of the aircraft and how to store energy harvested from them.

“Some of these challenges will be overcome by the researchers working under this AFOSR MURI within the next two years. In order to make the DSSCs’ solar energy harvester transferable to the wings of an UAV, additional engineering tasks remain, which may require another project to be funded for five additional years,” Taya said.

Given that solar cells that are larger have decreased efficiency, the researchers are using a metal grid, which has high surface resistance and can accelerate electron transport for larger-sized flexible DSSCs while maintaining high efficiency. (ANI)

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