Building a lighter, twistier, cheaper solar cell

Lighter. More flexible. Resilient. These are the core catchwords of the space industry. And Adelaide-based startup Spacelis thinks it’s cracked a significant challenge – solar panels.

Photovoltaics need materials that are conductive. And this must be set on a transparent substrate. In the case of traditional technology, that’s usually silver on silicon (glass).

Both components are heavy. Both are expensive to manufacture in highly pure forms.

But what if your solar cells are built on organic (non-mineral) materials?

“We use conductive polymers for the active area of solar cells,” says Spacelis founder Guler Kocak. “It’s a very big molecule, but this molecule has energy donor and acceptor parts”.

In essence, it can capture photons and transfer that energy in a similar way to that of metals like silver. Transparent plastic – such as the PET (polyethylene terephthalate) used in drink bottles – takes the place of glass.

“Altogether, it is very thin,” Kocak adds. “So you just need a millimetre to coat a huge surface area. That’s why it’s very cost-effective and eco friendly. It can even be done in the future with recycled materials.”

But, being both thin and plastic, such solar cells are also bendable.

“In our case, we want to use these flexible cells for space applications,” Kocak says. “They’re lightweight enough to be folded into small cube sats. They can also be used to coat a future space station, for example. But we need to test such large-scale application and integration with other electronic components”.

And that’s where her startup, Spacelis, is at.

It’s a matter of demonstrating the effectiveness and resiliency of organic technology.

It’s a matter of finding like-minded partners, such as CSIRO, to work with.

Kocak says the chief challenge of organic photovoltaic (OPV) cells had been figuring out how to get worthwhile power conversion efficiencies. But that’s now reached about 80 per cent that of silver-silicon cells.

“It will only get better, as you can always do laboratory work, find more organic materials and design new ones,” she says.

There are theoretical limits on how much current polymers can harvest and the long-term stability of such materials. But Kocak says researchers are constantly pushing back these boundaries. “This is the organic solar cell success story. The scientific community is shifting its attention to this kind of technology because of its eco-friendliness, versatility, and energy payback time. With these cells, you’ll get profitable returns much faster than silicon.”

Kocak says her research also examines how organic photovoltaic cells can be integrated into structural components, such as satellite antennas and rover casings. Ultimately, she hopes, the flexible power source will form part of spacesuits and protective sheets wrapped around Lunar and Mars-based equipment.

“That’s what I’m trying to learn in the business side of my solar cell journey – how to actually use these solar cells in space technologies,” Kocak says.